optiflow_infant_nasal_high_flow_clinical_paper_summ.pdf
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Adult Nasal High Flow: Clinical Paper Summaries
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Table of Contents
KEY REFERENCES ........................................................................................................... P1
THERAPY OVERVIEW
Research in high flow therapy (Dysart) ................................................................................................ S1
SPECIFIC PATIENT POPULATION
High-flow oxygen therapy in acute respiratory failure (Roca) ............................................................... S2
Long-term humidification therapy in chronic airway disease (Rea) ....................................................... S3
A randomized controlled trial to assess nasal high-flow oxygen in intensive care patients (Parke) ....... S4
High-flow nasal cannulae in post-cardiac surgical patients (Corley) ..................................................... S5
High-flow nasal oxygen in acute respiratory failure patients (Sztrymf) .................................................. S6
Nasal High-flow oxygen therapy in Do-Not-Intubate patients (Peters) .................................................. S7
Nasal High-flow oxygen therapy in patients undergoing bronchoscopy (Lucangelo) ............................. S8
MECHANISM OF ACTION
Delivery of low level positive airway pressure (Parke) .......................................................................... S9
Generation of positive airway pressure in adult volunteers (Groves) .................................................. S10
Humidification and lung mucociliary clearance (Hasani) .................................................................... S11
The effects of flow on airway pressure (Parke) .................................................................................. S12
Reliable delivery of FiO2 and delivery of positive pressure (Ritchie) ................................................... S13
BIBLIOGRAPHY (Infant & Adult)
Page 3
Adult Key References
Therapy Overview
1.
Physiological Outcomes
Kernick J, Magarey J. What is the evidence for the use of
high flow nasal cannula oxygen in adult patients admitted
to critical care units? A systemic review. Aust Crit Care.
2010; 23(2): 53-70.
http://www.ncbi
8.
Corley A, Caruana LR, Barnett AG, Tronstad O, Fraser
J.Oxygen delivery through high-flow nasal cannulae
increase end-expiratory lung volume and reduce
respiratory rate in post-cardiac surgical patients. Br J
Anaesth. Epub 2011 Sep 9.
http://www.ncbi
Clinical Outcomes
9. Groves N, Tobin A. High flow nasal oxygen generates
2.
Lucangelo U, Vassallo F, Marras E, Ferluga M, Beziza E,
Comuzzi L, Berlot G, Zin W. High-flow nasal interface
improves oxygenation in patients undergoing
bronchoscopy. Crit Care Res Pract. 2012;506382.
positive airway pressure in adult volunteers. Aust Crit
Care. 2007; 20(4): 126-31.
http://www.ncbi
10. Hasani A, Chapman T, McCool D, et al. Domiciliary
3.
Peters S, Holets S, Gay P. Nasal High Flow Oxygen
Therapy in Do-Not-Intubate Patients With Hypoxemic
Respiratory Distress. Respir Care. 2012
humidification improves lung mucociliary clearance in
patients with bronchiectasis. Chron Respir Dis. 2008;
5(2): 81-6.
http://www.ncbi
11. Parke R, McGuinness S, Eccleston M. Nasal high-flow
4.
Roca O, Riera J, Torres F et al. High-flow oxygen
therapy in acute respiratory failure. Resp Care. 2010;
55(4): 408-13.
http://www.ncbi
5.
Rea H, McAuley S, Jayaram L, et al. The clinical utility of
long-term humidification therapy in chronic airway
disease. Resp Med. 2010; 104(4): 525-33.
http://www.ncbi
therapy delivers low level positive airway pressure. Br J
Anaesth. 2009; 103(6): 886-90.
http://www.ncbi
12. Parke R, McGuinness S, Eccleston M. The effects of
flow on airway pressure during nasal high-flow oxygen
therapy. Respiratory Care. 2011; 56(81): 151-5.
http://www.ncbi
6. Parke R, McGuinness S, Eccleston M. A preliminary
randomized controlled trial to assess effectiveness of
nasal high-flow oxygen in intensive care patients. Resp
Care. 2011; 56(3): 265-70.
http://www.ncbi
7.
Sztrymf B, Messika J, Bertrand F. Beneficial effects of
humidified high flow nasal oxygen in critical care
patients. Intensive Care Med. 2011; 37(11): 1780-6
13. Ritchie JE, Williams AB, Gerard C,et al. Evaluation of a
humidified nasal high-flow oxygen system, using
oxygraphy, capnography and measurement of upper
airway pressures. Anaesth Intensive Care. 2011;
39(6):1103-10.
http://www.ncbi
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K Dysart, TL Miller, MR Wolfson, TH Shaffer
Respiratory Medicine 2009; 103: 1400-5
Research in high flow therapy: mechanisms of action
AIM:
To review proposed mechanisms for the efficacy of nasal high flow (NHF) therapy.
DETAILS:
NHF oxygen therapy is being increasingly utilized in a variety of patients with different diseases. The precise mechanisms
by which NHF oxygen therapy alters gas exchange and influences the respiratory system have not been fully elucidated.
However, available data suggest that there are five contributors to the effectiveness of NHF oxygen therapy.
Washout of nasopharyngeal deadspace: The most common reasons for needing to switch to invasive ventilation are
hypercapnia and apnoea secondary to hypercapnia. Therefore, if deadspace in the nasopharyngeal cavity (and overall
deadspace) is reduced, alveolar ventilation will be a greater fraction of minute ventilation. NHF oxygen therapy has been
shown to have an immediate effect on ventilation rates and to improve oxygenation, indicating that deadspace is reduced.
In addition, the results of animal studies of tracheal gas insufflation (TGI) support the notion that deadspace washout is a
lung protective strategy for acute lung injury.
Reduced work of breathing (WOB): The nasopharyngeal surface area, distensibility of the nasopharynx and gas volume all
contribute resistance to gas flow. NHF oxygen therapy provides nasopharyngeal gas flows that are equal to, or greater
than, a patient’s peak inspiratory flow thereby decreasing resistance which in turn translates into a reduction in resistive
WOB. The effects of NHF oxygen therapy on expiration are not as well understood. However, it is speculated that expiratory
efforts may be assisted secondary to a potential Coanda effect.
Improved mechanics: Even short periods inspiring gas at ambient temperature and humidity can significantly decrease
pulmonary compliance and conductance during mechanical ventilation in infants. Improved respiratory compliance has
been documented in infants receiving NHF oxygen therapy for respiratory support. These results indicate that, by reducing
distending pressure and therefore also functional residual volume, adequate conditioning of inspired gases during NHF
oxygen therapy affects physiological responses in the lung.
Reduced metabolic cost of gas conditioning: There is an energy cost associated with conditioning of inspired gases by the
upper airway. This cost is higher when gas is cooler and drier. Furthermore, the increase in minute ventilation that often
accompanies lung pathologies means that the volume of gas requiring conditioning is greater. Use of a NHF oxygen therapy
system that warms and humidifies inspired gas presumably reduces the energy required for gas conditioning.
Provision of distending pressure: Ventilatory mechanics can be improved by providing distending pressure to the lungs
which then improves lung compliance and gas exchange. There is the potential for continuous positive airway pressure
(CPAP) to be generated during NHF oxygen therapy. This is dependent on the leak rate which is in turn highly dependent on
the relationship between the size of nasal prongs and the nose, and requires the mouth to be closed. One clinical study in
infants receiving NHF oxygen therapy showed that pharyngeal pressure was correlated with flow and inversely correlated
with infant size.
CONCLUSION:
Delivery of warmed and humidified gases using NHF oxygen therapy is a viable treatment option, which is comfortable for
the patient and minimizes deterioration of nasopharyngeal structures.
KEY POINTS:
•
The five proposed mechanisms for the efficacy of NHF oxygen therapy are: washout of nasopharyngeal deadspace;
reduced WOB, improved mechanics; reduced metabolic cost of gas conditioning; and provision of distending
pressure.
•
HFT can be regarded as a viable device for gas conditioning.
•
Numerous studies have established the safety and efficacy of NHF in acute care.
•
There are some studies which demonstrated the application of NHF beyond conventional oxygen therapy.
RESEARCH IN HIGH FLOW T HERAPY (DYSART) | S1-P1
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K Dysart, TL Miller, MR Wolfson, TH Shaffer
Respiratory Medicine 2009; 103: 1400-5
DEFINITIONS:
Coanda effect
Continuous positive airway pressure (CPAP)
Functional residual volume
Hypercapnia
Mechanical ventilation
Minute ventilation
Nasal high flow (NHF) oxygen therapy
Tracheal gas insufflation (TGI)
Work of breathing (WOB)
A term originating from the field of aeronautical engineering. The
Coanda effect is an entrainment effect whereby high-speed fluid from a
nozzle entrains fluid from the body that it enters. An obstruction to this
action by a wall/barrier causes a low-pressure area on one side of the
jet, causing a deflection in flow, redirecting flow to the barrier
A technique of respiratory therapy in which airway pressure is
maintained above atmospheric pressure throughout the respiratory
cycle by pressurization of the ventilatory circuit
The volume in the lungs at the end-expiratory position
The presence of an abnormally high level of carbon dioxide in the
circulating blood
The use of an invasive artificial airway to mechanically assist or replace
spontaneous breathing, when patients cannot do so on their own
The volume of gas that moves in and out of the lungs in one minute; it
is calculated by multiplying the exhaled tidal volume by the respiratory
rate
A technique to provide a high flow of heated, humidified oxygen and
air to patients requiring respiratory support, delivered through nasal
cannulae
An adjunctive ventilatory technique that delivers fresh gas into the
trachea either continuously or only during a specific segment of the
respiratory cycle
The force required to expand the lung against its elastic properties
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
RESEARCH IN HIGH FLOW T HERAPY (DYSART) | S1-P2
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O Roca, J Riera, F Torres, JR Masclans
Respiratory Care 2010; 55(4): 408-13
High-flow oxygen therapy in acute respiratory failure
AIM:
To compare the subjective comfort of oxygen therapy given via conventional face mask (FM)versus nasal high flow (NHF)
cannula (Optiflow™; Fisher & Paykel) in patients with acute respiratory failure (ARF).
METHOD:
In this prospective, comparative study of sequential interventions, adult patients with ARF (defined as a blood oxygen
saturation [SpO2] <96% while receiving humidified oxygen via FM with a fraction of inspired oxygen [FiO2] of ≥0.5) were
given FM oxygen therapy humidified with a bubble humidifier (Respiflo Water and MN Adapter; Tyco Healthcare) for 30
minutes. Patients were then switched to NHF oxygen therapy for 30 minutes at an initial flow rate of 20–30 L/min, with a
FiO2 identical to that with the FM.
Perceived comfort (dyspnoea, mouth dryness and overall comfort) was assessed by the patients at the end of each 30minute treatment period using a visual analogue scale (VAS) ranging from 0 (lowest) to 10 (highest). Arterial blood gas
values, acid-base balance, respiratory rate and SpO2 were also measured at this time. At the end of both 30-minute
periods, patients were asked which oxygen delivery system they wanted to keep using.
RESULTS:
Twenty patients (median age 57 years; 14 males) were included in this study. The median duration of ARF was 4
(interquartile range 3–8) days prior to inclusion in the study, and 95% of patients were admitted to the intensive care unit
due to hypoxaemic ARF. Data for the primary and secondary endpoints are reported in the table. After 30 minutes of FM
oxygen therapy there were no significant differences in respiratory values from baseline. In contrast, a significant increase
in the partial pressure of oxygen (PaO2) and a reduction in respiratory rate without hypercapnia or acidosis was observed
after 30 minutes of NHF oxygen therapy. NHF oxygen therapy was generally well tolerated. Five patients (25%) reported
some mild adverse effects possibly related to NHF oxygen therapy. The most common effect, reported by three patients,
was cervical-thoracic discomfort which occurred during the initial period of increasing flow that disappeared when flow
was decreased, and one patient reported that the gas temperature was too high. All of these adverse effects were reported
early in the testing period and disappeared before the end of the 30-minute testing period. Other mild adverse events were
nonspecific nasal discomfort and nasal mucosal lesions in one patient. Nasal mucosal lesions were observed before the
initiation of NHF oxygen therapy in another patient and were considered probably related to prior use of a conventional
nasal cannula.
P value
Oxygen therapy
Subjective evaluation (VAS score)
Dyspnoea
Mouth dryness
Overall comfort
Respiratory and gas exchange variables
Total oxygen flow (L/min)
Fraction of delivered oxygen
Respiratory rate (breaths/min)
pH
PaO2 (mm Hg)
PaCO2 (mm Hg)
HCO3 (mmol/L)
Base excess (mmol/L)
SpO2 (%)
Haemodynamic variables
Mean arterial pressure (mm Hg)
Heart rate (beats/min)
NHF
FM
3.8 (1.3–5.8)
5 (2.3–7.0)
9.0 (8.0–10.0)
6.8 (4.1–7.9)
9.5 (8.0–10.0)
5.0 (2.3–6.8)
0.001
<0.001
<0.001
30.0 (21.3–38.7)
1.0 (0.8–1.0)
21 (18–27)
7.44 (7.38–7.50)
127 (83–191)
37 (32–43)
24.5 (22.2–29.1)
-1.0 (-2.3–5.3)
98 (96–99)
15.0 (12.0–20.0)
1.0 (0.8–1.0)
28 (25–32)
7.42 (7.38–7.47)
77 (64–88)
37 (33–45)
25.0 (22.1–28.5)
1.0 (-2.3–4.8)
95 (91–97)
<0.001
0.32
<0.001
0.06
0.002
0.51
0.09
0.055
0.002
86 (71–93)
85 (73–108)
87 (76–94)
94 (77–112)
0.36
>0.99
All values are median and interquartile range; FiO2 = fraction of inspired oxygen; HCO3– = blood bicarbonate; IQR = interquartile range; PaO 2 = partial
pressure of oxygen; PaCO2 = partial pressure of carbon dioxide; SpO2 = blood oxygen saturation as measured via pulse oximetry.
DISCUSSION:
This is the first study investigating the delivery of humidified NHF oxygen therapy in patients with ARF. NHF oxygen therapy
was associated with significantly less dyspnoea and mouth dryness, and greater overall comfort compared with FM oxygen
therapy. Patients found NHF oxygen therapy significantly more comfortable, and there may be several reasons for this. The
improvements in dyspnoea and mouth dryness played a part in improving patient-reported comfort. In addition, unlike FM
oxygen therapy, NHF oxygen therapy does not affect speaking and allows food ingestion, and this could also contribute to
improved patient comfort. After the testing period, all patients chose to continue with the NHF system.
HIGH-FLOW OXYGEN THER APY IN ACUTE RESPIRATORY FAIL URE (ROCA) | S2-P1
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O Roca, J Riera, F Torres, JR Masclans
Respiratory Care 2010; 55(4): 408-13
NHF oxygen therapy was also associated with greater oxygenation and a lower respiratory rate than FM oxygen therapy.
The improvements in oxygenation are an important effect of NHF oxygen therapy. Although FiO2 was not measured in this
study, greater oxygenation during NHF oxygen therapy may be a result of higher FiO2 secondary to the higher flow rate.
Furthermore, the NHF oxygen therapy heated humidifier system may have indirectly affected oxygenation and also might
attenuate the development of bronchial hyper-response symptoms. The adverse effects observed with NHF oxygen therapy
were mild and the system can be considered comfortable as was apparent from all patients choosing to continue with NHF
oxygen therapy after the testing period.
CONCLUSION:
NHF oxygen therapy is considered by patients to be more comfortable than FM oxygen therapy, and is better tolerated and
more effective in the management of ARF. Further investigation is needed to determine the clinical scenarios in which its
benefits will have the greatest impact.
KEY POINTS:
•
NHF oxygen therapy is associated with significantly less dyspnoea and mouth dryness, and greater overall comfort
compared with FM oxygen therapy in patients with ARF.
•
NHF oxygen therapy improves oxygenation and respiratory rates compared with FM oxygen therapy in patients with
ARF.
•
NHF oxygen therapy could play an important role in the integrated treatment of patients with ARF.
DEFINITIONS:
Acute respiratory failure (ARF)
A syndrome in which the respiratory system fails in one or both of its gas
exchange functions: oxygenation and carbon dioxide elimination. Acute
respiratory failure is characterised by life threatening derangements in
arterial blood gases and acid-base status
Dyspnoea
Laboured breathing or shortness of breath
Fraction of inspired oxygen (FiO2)
The fraction of oxygen in inspired gas
Interquartile range (IQR)
A descriptive statistic to measure statistical dispersion, being equal to the
difference between the third and first quartiles
Nasal high flow
A technique to provide a high flow of heated, humidified oxygen and air to
patients requiring respiratory support, delivered through nasal cannulae
Oxygen saturation (SpO2)
The amount of oxygen attached to the haemoglobin cell in the circulatory
system
Partial pressure of carbon dioxide (PCO2)
The part of total blood gas pressure exerted by carbon dioxide gas; a
measure of how much carbon dioxide is dissolved in the blood and how
well carbon dioxide is able to move out of the body
Oxygen saturation by pulse oximetry
(SpO2)
Oxygen saturation as measured by pulse oximetry
Partial pressure of oxygen (PaO2)
The part of total blood gas pressure exerted by oxygen gas; a measure of
how much oxygen is dissolved in the blood and how well oxygen is able to
move from the airspace of the lungs into the blood
pH
A measure of acidity or alkalinity
Visual analogue scale (VAS)
A technique to assess subjective levels of pain or discomfort on an
increasing scale, with visual cues for the patient that are related to a
numerical value
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
HIGH-FLOW OXYGEN THER APY IN ACUTE RESPIRATORY FAIL URE (ROCA) | S2-P2
Page 8
H Rea, S McAuley, L Jayaram, J Garrett, H Hockey, L Storey, G O’Donnell, L Haru,
M Payton, K O’Donnell
Respiratory Medicine 2010; 104: 525-33
The clinical utility of long-term humidification therapy in chronic airway disease
AIM:
To compare long-term humidification therapy (LTHT) with usual care on the frequency of exacerbations, lung function,
quality of life and exercise capacity in adults with chronic airway disease.
METHOD:
Patients with chronic obstructive pulmonary disease (COPD) or bronchiectasis entered this prospective, randomised,
single centre, open-label 12-month study. Those in the LTHT group (n=60) were to use the LTHT device for ≥2 hours
every day at home; concomitant usual therapy (e.g. corticosteroids, oral antibiotics) was allowed. The other group
continued to receive their usual treatment (n=48).
The Optiflow [Fisher & Paykel Healthcare] device, consisting of Optiflow nasal cannulae connected to an MR880
humidifier and HC210 flow source system, was used to deliver humidified air, fully saturated at 37 °C. Patients selected
a flow rate of either 20 or 25 mL/min.
Patients recorded exacerbations in their diaries; an exacerbation was defined as worsening of two or more respiratory
symptoms for two or more days requiring treatment. Three blinded investigators adjudicated exacerbation data.
Dyspnoea and quality of life were self-reported, using the Medical Research Council (MRC) Scale, and the St George’s
Respiratory Questionnaire (SGRQ), respectively. Lung function (using spirometry) and exercise capacity (using the 6
minute walk distance test [6MWD]) were also assessed.
RESULTS:
There was no significant difference between groups in exacerbation frequency, with 3.63 exacerbations/patient/year in
the usual care group and 2.97 in the LTHT group (primary endpoint; p=0.067). However, the number of exacerbation
days was significantly lower, and the median time to first exacerbation significantly longer, in the LTHT group (table).
Differences in the following lung function parameters were significant (all p<0.05) and favoured the LTHT group at 3 and
12 months: forced expiratory volume in 1 second (FEV1), percentage of predicted FEV1, forced vital capacity (FVC) and
percentage of predicted FVC. The FEV1/FVC ratio did not change significantly from baseline in either group at 3 months
or 12 months.
The SGRQ total score was significantly (p<0.05) lower (indicating improvement vs baseline) in the LTHT group than the
usual care group at 3 and 12 months, with differences in score of at least 5.9 points at 12 months (4 points is
considered to be clinically meaningful).
No significant difference was seen in exercise capacity.
Except for antibiotic use, which was significantly (p=0.008) lower in the LTHT group, overall medication use was similar
between the groups.
Most LTHT patients used the device for ≥1 hour/day (80% [48/60]) and 32% [19/60] used it for ≥2 hours/day). Mean
(standard deviation [SD]) use per day per patient was 1.6 (0.67) hours.
There were no serious adverse events related to study therapy.
Variables
Selected secondary endpoints
No. of days of exacerbation over 12
months (geometric mean)
No. of days to first exacerbation
(predicted median)
Pts with no exacerbations, n (%)
MRC dyspnoea scores at 12 months
(mean)
% change from baseline in 6MWD at
12 months
LTHT
Usual care
Ratio
Variables
18.2
33.5
52
27
12/60 (20.0%)
4/48 (8.3%)
0.544
(0.300,
0.985)
0.650a
(0.423,
0.999)
NA
2.49
2.54
NA
0.518
−4.0
−8.6
NA
0.485
0.045
0.050
0.043
% = percentage; 6MWD = 6 minute walking distance test; CI = confidence interval; LTHT = long-term humidification therapy; mo = month; MRC =
Medical Research Council; NA = not applicable; no. = number; pts = patients.
a. Hazard ratio
LONG-TERM HUMIDIFICATION THER APY IN CHRONIC AIRWAY DISEASE (REA)| S3-P1
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H Rea, S McAuley, L Jayaram, J Garrett, H Hockey, L Storey, G O’Donnell, L Haru,
M Payton, K O’Donnell
Respiratory Medicine 2010; 104: 525-33
DISCUSSION:
COPD and bronchiectasis are chronic airway disorders characterised by excess mucous production and recurrent
infective exacerbations. COPD and bronchiectasis are associated with with concomitant decline in lung function and
quality of life. This is the first long-term study of LTHT in patients with COPD or bronchiectasis. The primary endpoint
was not met, possibly because the study was under-powered or that patients with both COPD and bronchiectasis were
included. However, the 18.2% reduction in exacerbation rate with LTHT is within the range (15-25%) observed with best
medical therapy (e.g. with inhaled corticosteroids, long-acting β agonists and tiotropium).
This study did demonstrate that 1-2 hours/day of LTHT significantly reduced the number of exacerbation days and
increased the time to first exacerbation compared with usual care. It is postulated that LTHT enhances lung mucociliary
clearance, which is also suggested indirectly by the improvement in FEV1 and FVC without any change in the FEV1/FVC
ratio. Further investigation of the mechanism of improvement is required.
Study results are to be interpreted with some caution since a placebo control was not feasible because none could be
designed that would be undetectable by the patient. Compliance with LTHT was poorer than expected, with a mean of
1.6 hours/day versus 2 hours/day. Finally, differences in outcomes between patient subpopulations were not
determined, and this remains an area for further research.
CONCLUSION:
Daily LTHT for between 1 and 2 hours in patients with COPD or bronchiectasis led to significant improvement in the
number of days with exacerbations, the time to first exacerbation, lung function and quality of life. This therapy was well
tolerated.
KEY POINTS:
•
Patients with COPD or bronchiectasis experienced significant improvements with LTHT in the number of days with
exacerbations over a 12-month period, and a longer time to the first exacerbation, as compared with usual medical
care.
•
Daily LTHT of between 1 and 2 hours with Optiflow may improve lung function and quality of life.
DEFINITIONS:
Bronchiectasis
A chronic inflammatory condition or degenerative disease of the bronchi
which cases localized, irreversible dilation of part of the bronchial tree,
resulting in airflow obstruction and impaired mucous clearance
Chronic obstructive pulmonary disease
(COPD)
A progressive disease in which the small airways become narrowed,
limiting airflow to and from the lungs and causing shortness of breath. In
contrast to asthma, air flow limitation in COPD is poorly reversible
Forced expiratory volume in 1 second
(FEV1)
The volume of air that can be exhaled during the first second of a forced
exhalation
Forced vital capacity (FVC)
The determination of the vital capacity from a maximally forced expiratory
effort
Nasal high flow
A technique to provide a high flow of heated, humidified oxygen and air to
patients requiring respiratory support, delivered through nasal cannulae
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
LONG-TERM HUMIDIFICATION THER APY IN CHRONIC AIRWAY DISEASE (REA)| S3-P2
Page 10
RL Parke, SP McGuinness, ML Eccleston
Respiratory Care 2011; 56(3): 265-70
A preliminary randomized controlled trial to assess effectiveness of nasal high-flow oxygen in
intensive care patients
AIM:
To compare the effectiveness and tolerability of nasal high flow (NHF) oxygen therapy and standard high-flow face mask
(HFFM) oxygen therapy in patients with mild-to-moderate hypoxaemic respiratory failure in the intensive care unit (ICU).
METHOD:
In this prospective, single-centre study, 60 ICU patients with mild-to-moderate hypoxaemic respiratory failure were
randomized to receive humidified high-flow oxygen via either a NHF system (Optiflow, with MR880 humidifier, RT241
heated delivery tube, RT033 or RT034 nasal cannula; Fisher & Paykel Healthcare) or a HFFM system (standard face mask,
MR850 humidifier, RT308 heated delivery tube and air entrainer; Fisher & Paykel Healthcare) and an aerosol mask (Hudson
RCI; TFX Medical). NHF was initiated at a flow rate of 35 L/min, and then flow and the inspired oxygen fraction (FiO2) were
titrated to achieve an oxygen saturation by pulse oximetry (SpO2) or arterial blood gas (SaO2) of ≥95%. Patients in the HFFM
group received oxygen at 31ºC and 32 mg H2O/L also titrated to achieve SpO2 or SaO2 of ≥95%. Variables assessed were
rate of transfer to noninvasive ventilation (NIV), the partial pressure of arterial oxygen (PaO2)/FiO2 ratio, SpO2 and length of
hospital stay. Patients who failed on their randomized therapy (defined as worsening respiratory failure that required a
change in the respiratory support device within 24 hours after enrollment) were treated at the physician’s discretion.
RESULTS:
Data from 56 patients were available for analysis; there were no significant differences between the two treatment groups
in baseline demographics. Therapy success and desaturation data are reported in the table below. There was no significant
difference between the two groups in PaO2/FiO2, time to ICU discharge or hospital stay.
Success on allocated therapy (patients)
NIV required (patients)
≥1 desaturation (patients)
Mean number of desaturation episodes
Mean desaturations per patient
Mean desaturations per hour
NHF
26/29
3/29
8/19
15
0.79
0.21
HFFM
15/27
8/27
10/14
26
1.86
0.47
P value
0.006
0.10
0.16
0.009
HFFM = high-flow face mask; NHF = nasal high flow therapy; NIV = noninvasive ventilation.
DISCUSSION:
NHF has been shown to have good patient acceptability and to provide effective oxygenation. Potential explanations for the
clinical benefit observed in this study include generation of positive airway pressure and washout of anatomical
deadspace. Furthermore, humidification of inspired gases during long-term respiratory therapy has been shown to improve
lung function and decrease exacerbations, as well as contributing to patient comfort. Limitations of this study include
availability of desaturation data in only a subset of patients, and desaturation data were not detailed enough to perform a
comprehensive analysis.
CONCLUSION:
NHF was more successful than HFFM for the treatment of ICU patients with mild-to-moderate respiratory failure.
KEY POINTS:
•
NHF oxygen therapy is more successful than HFFM oxygen therapy in ICU patients with mild-to-moderate respiratory
failure.
•
NHF oxygen therapy has an increasing role as an option for respiratory therapy in the ICU.
DEFINITIONS:
Deadspace
The space in the trachea, bronchi, and other air passages which
contains air that does not reach the alveoli during respiration
Fraction of inspired oxygen (FiO2)
The fraction of oxygen in inspired gas
Intensive care unit (ICU)
A hospital facility providing intensive nursing and medical care for
critically ill patients
A RANDO MI ZED CONTROLLED TRIAL TO ASSESS N ASAL HI GH-FLOW OXYGEN IN INTENSIVE CARE PATIENTS (PARKE) | S4-P1
Page 11
RL Parke, SP McGuinness, ML Eccleston
Respiratory Care 2011; 56(3): 265-70
High-flow face mask (HFFM)
A full-face mask that is used to deliver high-flow gases to a patient
during ventilatory support
Nasal high flow therapy (NHF)
A technique to provide a high flow of heated, humidified oxygen and
air to patients requiring respiratory support, delivered through nasal
cannulae
Noninvasive ventilation (NIV)
The delivery of ventilatory support without the need for an invasive
artificial airway
Oxygen saturation by arterial blood gas
analysis (SaO2)
Oxygen saturation as measured by arterial blood gas analysis
Oxygen saturation by pulse oximetry (SpO2)
Oxygen saturation as measured by pulse oximetry
Partial pressure of arterial oxygen (PaO2)
The part of total blood gas pressure exerted by oxygen gas; a measure
of how much oxygen is dissolved in the blood and how well oxygen is
able to move from the airspace of the lungs into the blood
pH
A measure of acidity or alkalinity
Visual analogue
A technique to assess subjective levels of pain or discomfort on an
increasing scale, with visual cues for the patient that are related to a
numerical value
scale (VAS)
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
A RANDO MI ZED CONTROLLED TRIAL TO ASSESS N ASAL HI GH-FLOW OXYGEN IN INTENSIVE CARE PATIENTS (PARKE) | S4-P2
Page 12
A Corley, LR Caruana, AG Barnett, O Tronstad, JF Fraser
British Journal of Anaesthesia 2011; 1-7
Oxygen delivery through high-flow nasal cannulae increase end-expiratory lung volume and reduce
respiratory rate in post-cardiac surgical patients
AIM:
To assess the effects of high-flow oxygen therapy (HFOT) using high-flow nasal cannulae (HFNCs) compared with low-flow
oxygen therapy on airway pressure (Paw) and end-expiratory lung volume (EELV). To identify a relationship, if any, between
peak airway pressure and EELV.
METHOD:
In this prospective, non-randomised, interventional study, adult patients requiring HFOT after cardiac surgery (n=20) had a
local anaesthetic nasal spray and nasal feeding tube fitted while sitting upright. Paw was measured using a precision
pressure transducer [PPT-001, DWWW2V, Honeywell International Ltd] that was attached to the feeding tube. Changes in
EELV were assessed indirectly via measurement of end-expiratory lung impedance (EELI) using an electrical impedance
tomography (EIT) kit [EIT Evaluation Kit 2, Dräger Medical].
Air pressure and lung volume 2 min readings were taken simultaneously, first during low-flow oxygen therapy (face mask
[FM] oxygen or nasal oxygen cannula) and then, following a 15 min washout period, during HFOT with the Optiflow system
(MR850 heated and humidified, RT202 delivery tubing and RT050/051 nasal cannulae) [Fisher and Paykel Healthcare]. The
OptiflowTM humidifier temperature was set to 37 °C and the fraction of inspired oxygen (FiO2) titrated on an individual basis
to maintain blood oxygen saturation (measured via pulse oximetry [SpO2]) of ≥95%, with the flow rate initiated at 35 L/min
and uptitrated to a maximum of 50 L/min. Measurements were taken with the patient’s mouth both open and closed.
FiO2 was also estimated during low-flow oxygen therapy. Other variables included respiratory rate, tidal impedance
variation (VARt), oxygenation (ratio of partial pressure of arterial oxygen [PaO2] to FiO2) and subjective rating of dyspnoea
(modified Borg score).
RESULTS:
HFOT with HFNC significantly increased mean Paw, EELI, VARt and oxygenation compared with low-flow oxygen therapy
(table). The respiratory rate was lowered significantly with HFOT, and there was a trend to improved subjective dyspnoea.
There was a strong positive correlation between Paw and EELI (correlation coefficient=0.7; p<0.001). The mean percentage
increase in EELI with HFOT as compared with low-flow oxygen therapy was greater in patients with a higher body mass
index (BMI) [13.3% in those with BMI of 25 kg/m2 versus 24.4% in thus with BMI of 40 kg/m2].
Variable
EELI (units)
Paw (cm H2O)
Respiratory rate
(beats/min)
Borg score 0–10
Tidal variation (units)
PaO2/FiO2 (mm Hg)
P value
Low-flow oxygen
HFOT with HFNC
Mean (SD)
419 (212.5)
-0.3 (0.9)
Mean (SD)
1936 (212.9)
2.7 (1.2)
Mean (SD)
1517 (46.6)
3.0 (1.3)
95% CI
1425, 1608
2.4,3.7
<0.001
<0.001
20.9 (4.4)
17.5 (4.6)
-3.4 (2.8)
−2.0, −4.7
<0.001
2.7 (2.6)
1512 (195.0)
160 (53.7)
1.9 (2.3)
1671 (195.1)
190.6 (57.9)
-0.8 (1.2)
159 (21.6)
30.6 (25.9)
−0.1, −1.4
117, 201
17.9, 43.3
0.023
<0.001
<0.001
Difference
95% CI = 95% confidence interval; EELI = end-expiratory lung impedance; FiO2 = fraction of inspired oxygen; HFOT = high-flow oxygen therapy;
HFNC = high-flow nasal cannula; PaO2 = partial pressure of arterial oxygen; Paw = airway pressure; SD = standard deviation.
DISCUSSION:
Pulmonary complications after cardiac surgery are common. HFNCs are used to deliver high-flow humidified air and oxygen
via wide-bored nasal cannulae at a set FiO2. This is the first study to show that HFOT delivered by HFNC after cardiac surgery
increases EELI in adults, suggesting increased lung volumes and functional residual capacity. Furthermore, increases in
EELI were significantly influenced by BMI, suggesting that patients with a higher BMI may benefit from HFNC-induced lowlevel positive Paw and increases in lung volume.
HFNC use also increased Paw by 3.0 cm over that achieved with low-flow oxygen therapy. This increase was correlated with
the increase in EELI. Positive airway pressure then improves lung volume, and concomitantly improves respiratory rate,
subjective dyspnoea and oxygenation.
Further research is required to confirm these study results because gas flow rates were not standardized across patients,
and the sample size was small.
HIGH-FLOW NASAL CANN ULAE IN POST-CAR DIAC SURGICAL PATIENTS (CORLEY) | S5-P1
Page 13
A Corley, LR Caruana, AG Barnett, O Tronstad, JF Fraser
British Journal of Anaesthesia 2011; 1-7
CONCLUSION:
HFOT with HFNCs provides a modest increase in oropharyngeal Paw that appears to result in clinically significant increases
in EELV as compared with low-oxygen therapy. Patients experiencing respiratory dysfunction after cardiac surgery,
particularly those with a high BMI or who cannot tolerate non-invasive ventilation, may benefit from HFNC.
KEY POINTS:
•
HFNCs increase airway pressure as compared with low-flow oxygen therapy, and this increase is significantly
correlated with increases in EELV.
•
Lung tidal volume, respiratory rate, subjective dyspnoea and oxygenation were also improved after HFOT versus lowoxygen therapy.
•
Benefits of HFOT were greatest in patients with a higher BMI.
DEFINITIONS:
95% confidence interval (CI)
Airway pressure (Paw)
Electrical impedance tomography (EIT)
End-expiratory lung impedance (EELI)
End-expiratory lung volume (EELV)
Fraction of inspired oxygen (FiO2)
High-flow nasal cannula (HFNC)
High-flow oxygen therapy (HFOT)
Nasal oxygen cannula
Oxygen saturation by pulse oximetry
(SpO2)
Partial pressure of arterial oxygen (PaO2)
Tidal volume (VT)
Tidal impedance variation (VARt)
A statistical measure showing that 95% of the results for that parameter
lie within the range quoted
Pressure in the airway
A non-invasive, real-time imaging method that produces cross-sectional
images of the lung during ventilation
Impedance during EIT at the end-expiratory position; used as indirect
measure of end-expiratory lung volume
The volume in the lungs at the end-expiratory position
The fraction of oxygen in inspired gas
Nasal cannula (a small, half-moon shaped plastic tube, the ends of which
fit into the nostrils of a patient) designed to deliver gas at a high flow rate
Delivery of oxygen gas at a high flow rate
A small, half-moon shaped plastic tube, the ends of which fit into the
nostrils of a patient, which is used to deliver oxygen at a concentration
higher than that in ambient air
Oxygen saturation as measured by pulse oximetry
The part of total blood gas pressure exerted by oxygen gas; a measure of
how much oxygen is dissolved in the blood and how well oxygen is able to
move from the airspace of the lungs into the blood
The volume inspired or expired per breath
The difference between impedance at the end of inspiration and expiration
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
HIGH-FLOW NASAL CANN ULAE IN POST-CAR DIAC SURGICAL PATIENTS (CORLEY) | S5-P2
Page 14
Sztrymf B, Messika J, Bertrand F, Hurel D, Leon R, Dreyfuss D, Ricard J-D
Intensive Care Medicine 2011; 37 (11): 1780-6
Beneficial effects of humidified high flow nasal oxygen in critical care patients: a prospective pilot
study
AIM:
To investigate the effects of high-flow nasal cannula (HFNC) oxygen therapy on respiratory parameters and outcomes in
intensive care unit (ICU) patients with acute respiratory failure (ARF).
METHOD:
This prospective, observational study included patients admitted to the ICU for ARF or persistent signs of respiratory
distress. All patients were switched from conventional oxygen therapy given via a high fraction of inspired oxygen (FiO2)
nonrebreathing facemask (Hudson RCI; Teleflex Medical) to HFNC oxygen therapy given using the Optiflow™ system (Fisher
& Paykel Healthcare). All procedures were part of routine clinical care. Respiratory, haemodynamic and clinical variables
were assessed at baseline and at specific times over the first 48 hours after switching to HFNC. Arterial blood gases were
measured at baseline and after 1 and 24 hours. Device noise and patient discomfort were measured throughout HFNC
oxygen therapy using a visual numeric scale ranging from 0-10.
RESULTS:
Thirty-eight patients (mean age 54.2 years) were included. The mean Simplified Acute Physiology Score (SAPS II) was 39 ±
10. The three most common causes of ARF were community-acquired pneumonia (n=15), H1N1 influenza infection (n=5)
and cardiogenic pulmonary oedema (n=5). Mean duration of HFNC therapy was 2.8 ± 1.8 days.
Compared to baseline, switching to HFNC oxygen therapy was associated with statistically significant reductions in
respiratory rate (p=0.009) and pulse oximetry (p<0.005) after 15 min, and in dyspnoea score, supraclavicular retraction and
thoracoabdominal asynchrony after 30 min (all p<0.05). Statistically significant reductions in heart rate were seen 6 hours
after switching to HFNC.
Changes in arterial blood gases are reported in the following table.
Mean ± SD
PaO2 (mm Hg)
PaO2/FiO2 ratio
PaCO2 (mm Hg)
pH
Baseline
141 ± 106
169 ± 108
38 ± 11
7.43 ± 0.09
HFNC oxygen therapy
1h
95 ± 40
187 ± 86
37 ± 11
7.44 ± 0.07
P value
24h
102 ± 23
38 ± 10
7.41 ± 0.07
0.009
0.036
0.77
0.87
FiO2 = fraction of inspired oxygen; PaO2 = partial pressure of oxygen; PaCO2 = partial pressure of carbon dioxide; SD = standard
deviation.
There was no change in noise or nasal discomfort scores from the beginning to the end of the study. No patient
discontinued NFHC oxygen therapy because of intolerance. Secondary intubation and mechanical ventilation was required
in 9 patients. Significant predictors of intubation were no decrease in respiratory rate, a high level of thoracoabdominal
asynchrony, and lower SpO2, PaO2 and PaO2/FiO2 ratio after initiation of HFNC oxygen therapy.
DISCUSSION:
HFNC oxygen therapy is widely used in neonates, but fewer data are available on its usefulness in adults. Data from this
prospective trial confirm that HFNC is well tolerated in adults, and is associated with early, sustained and beneficial effects
on oxygenation and clinical parameters. In addition, predictors that may assist in identifying patients who are most likely
to require intubation were identified. The results indicated that non invasive ventilation, or intubation and mechanical
ventilation, might be avoided in more than 75% of patients receiving HFNC. This pilot study provides sufficient rationale to
justify conducting a randomized controlled clinical trial to investigate the potential of HFNC oxygen therapy to reduce the
intubation rate in patients with hypoxaemic ARF.
CONCLUSION:
HFNC oxygen therapy had a beneficial effect on oxygenation and clinical outcomes in patients with ARF in the ICU.
HIG H-FLOW NASAL OXYGEN IN ACUTE RESPIRATORY FAILURE PATIENTS (SZTRYMF)| S6-P1
Page 15
Sztrymf B, Messika J, Bertrand F, Hurel D, Leon R, Dreyfuss D, Ricard J-D
Intensive Care Medicine 2011; 37 (11): 1780-6
KEY POINTS:
• HFNC oxygen therapy is associated with early and sustained beneficial effects on clinical respiratory parameters in
patients with acute respiratory failure.
•
HFNC oxygen therapy improves oxygenation in adult ICU patients with acute respiratory failure.
•
HFNC oxygen therapy is well tolerated in adult ICU patients with acute respiratory failure.
•
HFNC oxygen therapy may be associated with a reduction in the requirement for mechanical ventilation.
•
Respiratory rate may be a useful early predictor of HFNC oxygen therapy failure.
DEFINITIONS:
Acute respiratory failure (ARF)
A syndrome in which the respiratory system fails in one or
both of its gas exchange functions: oxygenation and carbon
dioxide elimination. Acute respiratory failure is characterised
by life-threatening derangements in arterial blood gases and
acid-base status
The fraction of oxygen in inspired gas
Fraction of inspired oxygen (FiO2)
Intensive care unit (ICU)
A hospital facility providing intensive nursing and medical
care for critically ill patients
High flow nasal cannulae (HFNC) oxygen therapy
A device designed to provide a high flow of heated,
humidified oxygen and air to patients requiring respiratory
support, delivered through nasal cannulae
The use of an invasive artificial airway to mechanically assist
or replace spontaneous breathing, when patients cannot do
so on their own
Oxygen saturation as measured by pulse oximetry
Mechanical ventilation
Oxygen saturation (SpO2)
Partial pressure of carbon dioxide (PaCO2)
Partial pressure of oxygen (PaO2)
The part of total blood gas pressure exerted by carbon
dioxide gas; a measure of how much carbon dioxide is
dissolved in the blood and how well carbon dioxide is able to
move from the airspace of the lungs into the blood
The part of total blood gas pressure exerted by oxygen gas; a
measure of how much oxygen is dissolved in the blood and
how well oxygen is able to move from the airspace of the
lungs into the blood
inScience Communications
© 2012 Fisher & Paykel Healthcare Ltd. Independently written by inScience Communications, Springer International Publishing AG, on behalf of Fisher & Paykel
Healthcare Ltd . All rights reserved. No part of this publication may be reproduced by any process in any language without written consent of the copyright holder.
Although great care has been taken to ensure that the information in this publication is accurate, neither inScience nor Fisher & Paykel shall be held responsible or in
any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.
HIG H-FLOW NASAL OXYGEN IN ACUTE RESPIRATORY FAILURE PATIENTS (SZTRYMF)| S6-P1
Page 16
SG Peters, SR Holets, PC Gay
Respiratory Care 2012; 6 July
Nasal high flow oxygen therapy in do-not-intubate patients with hypoxemic respiratory distress
AIM:
To assess the effectiveness of high-flow nasal cannula (HFNC) oxygen therapy in Do-Not-Intubate (DNI) patients with
hypoxaemia and mild hypercapnia.
METHOD:
The medical records of patients receiving HFNC oxygen therapy in the medical or medical-surgical intensive care unit (ICU)
between May 2009 and May 2011 were retrospectively analyzed. Patients had clinical evidence of respiratory distress,
hypoxaemia and mild or compensated hypercapnia (arterial carbon dioxide pressure [PaCO2] ≤65 mm Hg, pH >7.28) and a
Do-Not-Resuscitate or DNI status. HFNC oxygen therapy was delivered using the Optiflow system (Fisher & Paykel), which
included the MR850 respiratory humidifier plus a chamber, heated delivery tubing, and a small or large bore nasal cannula.
Therapy was initiated at a flow rate of 35 L/min and titrated up to 45-60 L/min if tolerated. The fraction of inspired oxygen
(FiO2) was titrated to maintain arterial oxygen saturation (SaO2) at >90% or as determined by the clinician. The primary
endpoint was need for escalation to noninvasive ventilation (NIV). Ventilation and gas exchange parameters (secondary
endpoints) were extracted using the closest values prior to initiation of HFNC oxygen therapy and approximately 1 hour
later. Patient tolerance of HFNC oxygen therapy was also assessed.
RESULTS:
Fifty patients (25 male & 25 female; age 27-96 [mean 73] years) were included. Flow rate during therapy was 30-60 (mean
42.6) L/min. Arterial blood gas data were only available in 23 patients after initiation of HFNC oxygen therapy. Duration of
NFNC oxygen therapy was 2-144 hours (mean 41.9 hours, median 30 hours). Data on primary and secondary endpoints are
shown in the table. No patient reported nasal bleeding or facial skin breakdown during HFNC oxygen therapy.
PaO2 (mm Hg)
PaCO2 (mm Hg)
pH
Respiratory rate (breaths/min)
Oxygen saturation (%)
Escalation to NIV [patients(%)]
Before HFNC
HFNC
66.5 (39-121)
42.3 (26-65)
7.42 (7.30-7.51)
30.6
89.1
95.4
40.2
7.43
24.7a
94.7a
9/50 (18%)
Values are means unless otherwise stated, followed by range where data available.
a
p<0.001 vs before HFNC oxygen therapy.
HFNC, high-flow nasal cannula oxygen therapy; NIV, noninvasive ventilation; PaCO2, arterial pressure of carbon dioxide; PaO2, arterial
pressure of oxygen.
DISCUSSION:
Patients with a DNI order are often transferred to the ICU specifically for initiation of NIV. Although this study was conducted
in ICU patients, it is possible that the use of HFNC oxygen therapy might allow delivery of adequate oxygenation without the
requirement for admission to the ICU. The rate of progression to NIV in this series of relatively ill patients was quite low at
18%.
CONCLUSION:
Use of HFNC oxygen therapy improved oxygenation and respiratory rate in patients with hypoxaemic respiratory distress,
with a low rate of progression to NIV.
KEY POINTS:
• HFNC oxygen therapy improves oxygenation and the respiratory rate in DNI patients with respiratory distress.
•
HFNC oxygen therapy is well tolerated in DNI patients with respiratory distress.
•
Use of HFNC oxygen therapy in DNI patients with respiratory distress has a low rate of progression to NIV.
NASAL HIGH FLOW OXYGEN THERAPY IN DO-NOT-INTUBATE PATIENTS WITH HYPOXEMIC RESPIRATORY DISTRESS (PETERS) I S7-P1
Page 17
SG Peters, SR Holets, PC Gay
Respiratory Care 2012; 6 July
DEFINITIONS:
Fraction of inspired oxygen (FiO2)
The fraction of oxygen in inspired gas
High-flow nasal cannula (HFNC)
oxygen therapy
A device designed to provide a high flow of heated, humidified oxygen and air to
patients requiring respiratory support, delivered through nasal cannulae
Intensive care unit (ICU)
A hospital facility providing intensive nursing and medical care for critically ill
patients
Noninvasive ventilation (NIV)
The delivery of ventilatory support without the need for an invasive artificial airway
Oxygen saturation of of arterial
blood (SaO2)
Oxygen saturation of the haemoglobin of arterial blood
Partial pressure of arterial carbon
dioxide (PaCO2)
The part of total blood gas pressure exerted by carbon dioxide gas; a measure of
how much carbon dioxide is dissolved in the blood and how well carbon dioxide is
able to move from the airspace of the lungs into the blood
Partial pressure of arterial
oxygen (PaO2)
The part of total blood gas pressure exerted by oxygen gas; a measure of how
much oxygen is dissolved in the blood and how well oxygen is able to move from
the airspace of the lungs into the blood
inScience Communications
© 2012 Fisher & Paykel Healthcare Ltd. Independently written by inScience Communications, Springer International Publishing AG, on behalf of Fisher & Paykel
Healthcare Ltd . All rights reserved. No part of this publication may be reproduced by any process in any language without written consent of the copyright holder.
Although great care has been taken to ensure that the information in this publication is accurate, neither inScience nor Fisher & Paykel shall be held responsible or in any
way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.
NASAL HIGH FLOW OXYGEN THERAPY IN DO-NOT-INTUBATE PATIENTS WITH HYPOXEMIC RESPIRATORY DISTRESS (PETERS) I S7-P2
Page 18
U Lucangelo, F Vassallo, E Marras, M Ferluga, E Beziza, L Comuzzi, G Berlot, W Zin
Critical Care Research and Practice 2012, 1-6
High-flow nasal interface improves oxygenation in patients undergoing bronchoscopy
AIM:
To compare the effects of oxygen therapy delivered via Venturi mask or high-flow nasal cannula (HFNC) on gas exchange and
cardiovascular parameters in patients undergoing bronchoscopy and bronchoalveolar lavage (BAL) fluid collection for the
diagnosis of pulmonary disease. In addition, the generation of continuous positive airway pressure (CPAP) during use of the
different oxygen therapy systems was determined in healthy volunteers.
METHOD:
Patients aged ≥18 years with oxygen saturation (SpO2) ≥90% and without cardiac or respiratory failure were randomized to
receive oxygen during bronchoscopy by one of three different strategies: via Venturi face mask (OS/62 K; FIAB) at 40 L/min
(V40), via HFNC (Fisher & Paykel) at 40 L/min (N40) or HFNC at 60 L/min (N60). In the V40 group gas delivery was controlled
using an air entrainer with Venturi effect (RT008; Fisher & Paykel), and in the N40 and N60 groups gas delivery was
controlled using a continuous high-flow generator with Venturi effect (9293/D; Harol). In all groups the inspired oxygen
fraction (FiO2) was 50%, and gases were heated and humidified using a servo-controlled heated respiratory humidifier
(MR730; Fisher & Paykel). Fibreoptic bronchoscopy (18-F; Olympus Corp.) was performed using a dedicated mouthpiece
(Pentax). BAL was done using 150mL of warmed saline solution. Measurement of gas exchange and respiratory parameters
was made at baseline, at the end of bronchoscopy and after a 10-minute rest period during which all patients were switched
to V40. Patients rated comfort during bronchoscopy on a scale from 1 (excellent) to 4 (poor).
Volunteers underwent simulated bronchoscopy and received oxygen delivered at V40, N40 and N60. Airway pressure was
measured using a catheter positioned in the pharynx.
RESULTS:
Forty-five patients (21 female & 24 male; aged 37-83 years; 15 per group) and eight volunteers (4 female & 4 male; age 2537 years) were enrolled. Data for gas exchange and cardiovascular parameters are shown in the table. Patient comfort ratings
were similar in the three treatment groups. HFNC oxygen therapy was well tolerated.
No measurable end-expiratory pressure was generated in volunteers receiving V40 or N40, but a median end-expiratory
pressure of 3.6 cm H2O was detecting with N60.
Median (1st-3rd quartile)
PaCO2 (mm Hg)
V40
N40
N60
PaO2/FiO2
V40
N40
N60
a/A PO2
V40
N40
N60
PaO2 (mm Hg)
V40
N40
N60
SpO2 (%)
V40
N40
N60
HR (beats/min)
V40
N40
N60
MAP (mm Hg)
V40
N40
N60
Baseline
End of bronchoscopy
10 minutes after
bronchoscopy
37.5 (35.0-42.1)
39.1 (37.3-41.5)
39.6 (33.4-42.5)
42.7 (41.0-44.4)a
43.2 (37.9-47.6)a
43.6 (42.4-48.0)ac
42.2 (39.7-43.2)a
43.4 (41.0-45.7)a
40.7 (38.0-45.5)
322.4 (295.6-374.3)
342.8 (295.7-371.9)
350.9 (304.3-363.8)
165.0 (127.4-199.2)a
140.6 (125.6-153.6)a
244.8 (181.6-366.8)cd
248.6 (206.6-274.3)ab
224.3 (206.6-249.1)ab
278.8 (222.9-304.0)a
0.674 (0.587-0.764)
0.723 (0.652-0.745)
0.718 (0.659-0.765)
0.265 (0.207-0.326)a
0.224 (0.204-0.249)a
0.401 (0.295-0.604)acd
0.441 (0.342-0.515)ab
0.421 (0.352-0.446)ab
0.480 (0.389-0.536)a
67.7 (62.1-78.6)
72.0 (62.1-78.1)
73.7 (63.9-76.4)
82.5 (63.7-99.6)
70.3 (62.8-76.8)
122.4 (90.8-183.4)ad
87.0 (72.3-101.8)
78.5 (72.3-87.2)
97.6 (78.0-106.4)ab
94 (93-96)
95 (91-96)
95 (93-97)
94 (92-96)
92 (90-95)
98 (97-99)acd
95 (92-98)
93 (91-95)
95 (95-98)bc
75.0 (62.0-97.0)
78.0 (72.0-85.0)
74.0 (68.0-84.0)
90 (76-110)a
84 (80-101)
84 (70-100)a
82.0 (75.0-90.0)b
80.0 (79.0-91.0)a
76.0 (64.0-89.0)b
94.0 (90.0-107.0)
102.0 (92.0-112.0)
109.0 (100.0-117.0)
108.0 (92.0-126.0)
99.0 (94.0-105.0)
103.0 (93.0-117.0)
91.0 (83.0-103.0)
94.0 (85.0-98.0)b
96.0 (87.0-108.0)
a p<0.05 vs baseline; b p<0.05 vs during bronchoscopy; c p<0.05 vs V40; d p<0.05 vs N40.
a/A PO2, ratio between arterial and alveolar oxygen pressure; HR, heart rate; MAP, mean arterial pressure; PaCO2, arterial pressure of carbon dioxide;
PaO2/FiO2, ratio between arterial oxygen pressure and inspiratory fraction of oxygen; SpO2, peripheral oxygen saturation.
HIGH-FLOW NASAL INTERFACE IMPROVES OXYGENATION IN PATIENTS UNDERGOING BRONCHOSCOPY (LUCANGELO) | S8-P1
Page 19
U Lucangelo, F Vassallo, E Marras, M Ferluga, E Beziza, L Comuzzi, G Berlot, W Zin
Critical Care Research and Practice 2012, 1-6
DISCUSSION:
This appears to be the first study investigating the effect of HFNC oxygen therapy on gas exchange and cardiovascular
parameters in patients undergoing bronchoscopy and BAL. Gas exchange is usually impaired during bronchoscopy as a
result of sedation and ventilation-perfusion mismatch. The significant improvements observed in gas exchange during HFNC
oxygen therapy at a rate of 60 L/min may be due to the low level of CPAP generated during therapy.
CONCLUSION:
HFNC oxygen therapy at a flow rate of 60 L/min significantly improved oxygenation during bronchoscopy and recovery
compared with oxygen therapy delivered via a face mask at 40 L/min.
KEY POINTS:
•
HFNC oxygen therapy at 60 L/min improves oxygenation during bronchoscopy and recovery.
•
HFNC oxygen therapy at 60 L/min generates a low level of CPAP.
•
CPAP generation during HFNC oxygen therapy at 60 L/min may contribute to improved oxygenation.
DEFINITIONS:
Arterial/alveolar oxygen pressure
(a/A PO2)
Continuous positive airway
pressure (CPAP)
Fraction of inspired oxygen (FiO2)
High-flow nasal cannula (HFNC)
oxygen therapy
Oxygen saturation by pulse
oximetry (SpO2)
Partial pressure of arterial carbon
dioxide (PaCO2)
Partial pressure of arterial oxygen
(PaO2)
Ratio between arterial and alveolar oxygen pressure
A technique of respiratory therapy in which airway pressure is maintained above
atmospheric pressure throughout the respiratory cycle by pressurization of the
ventilatory circuit
The fraction of oxygen in inspired gas
A device designed to provide a high flow of heated, humidified oxygen and air to
patients requiring respiratory support, delivered through nasal cannulae
Oxygen saturation as measured by pulse oximetry
The part of total blood gas pressure exerted by carbon dioxide gas; a measure of
how much carbon dioxide is dissolved in the blood and how well carbon dioxide is
able to move from the airspace of the lungs into the blood
The part of total blood gas pressure exerted by oxygen gas; a measure of how much
oxygen is dissolved in the blood and how well oxygen is able to move from the
airspace of the lungs into the blood
inScience Communications
© 2012 Fisher & Paykel Healthcare Ltd. Independently written by inScience Communications, Springer International Publishing AG, on behalf of Fisher & Paykel Healthcare
Ltd . All rights reserved. No part of this publication may be reproduced by any process in any language without written consent of the copyright holder. Although great care
has been taken to ensure that the information in this publication is accurate, neither inScience nor Fisher & Paykel shall be held responsible or in any way liable for the
continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.
HIGH-FLOW NASAL INTERFACE IMPROVES OXYGENATION IN PATIENTS UNDERGOING BRONCHOSCOPY (LUCANGELO) | S8-P2
Page 20
R Parke, S McGuinness, M Eccleston
British Journal of Anaesthesia 2009 Dec; 103(6): 886-90
Nasal high-flow therapy delivers low level positive airway pressure
AIM:
To compare the level of positive airway pressure generated by a new respiratory support therapy, Nasal High Flow (NHF)
using the Optiflow™ system, with that of a traditional facemask.
METHOD:
A 10F catheter was inserted into the nasopharynx of adults who had undergone elective cardiothoracic surgery; all patients
were in the cardiothoracic ICU and were still sedated and ventilated at the time of catheter insertion. The next day,
following extubation, patients received respiratory support with a heated and humidified oxygen/air blend delivered using
the Optiflow™ system (MR880 Heated Humidifier plus RT241 heated delivery tube; Fisher & Paykel Healthcare) with either
the Optiflow™ wide-bore nasal cannula (NHF) or a traditional facemask as the patient interface. Nasopharyngeal airway
pressure was measured using a pressure transducer connected to the previously placed catheter, as the most reasonable
surrogate for transpulmonary pressure.
Humidified oxygen therapy (target 37°C, Absolute Humidity 44 mg H2O) at 35 L/min was administered for approximately 15
minutes using the Optiflow™ system to allow patients to acclimatize their breathing patterns. Airway pressure was then
measured during 1 minute of quiet breathing, and then repeated after the interface was changed to a standard facemask
(Medium Adult SEE-THRU® O2 Mask; Hudson Respiratory Care Inc.). Measurements were recorded with mouth open and
closed, and a washout period of 5 minutes was allowed between each trial.
RESULTS:
19 patients (17 men and 2 women, mean age 63 years) were recruited into the study, and data from 15 were analysed
– 4 were excluded because they returned from theatre in a critical condition, or the catheter was dislodged before
measurements could be taken.
Significantly higher mean airway pressures were recorded when the NHF versus facemask interface was used in both the
mouth closed condition (mean 2.7 vs. 0.2 mm H20; p = 0.001) and the mouth open condition (0.76 vs. 0.39, p =0.001). The
closed-mouth airway pressure was significantly greater than the open mouth (2.7 vs. 0.76; p < 0.001) with the NHF
interface, but there was no significant difference between the 2 conditions when a facemask was used (0.63 vs. 0.39; p =
0.5).
DISCUSSION:
NHF is a new respiratory support system that has until now been little studied in adults requiring respiratory support. The
use of NHF therapy for neonatal care continues to gain increasing acceptance and has shown comparable efficacy to CPAP
in this population, while NHF has also demonstrated pressure generating effects in adult volunteers. In this study,
significant positive airway pressure was generated by the Optiflow™ NHF system when compared to a traditional facemask
at the same flow rates, in adults recovering from surgery. Although the pressure generated was greater when the mouth
was closed, it was still significant when the mouth was open.
This trial is the first to demonstrate a positive airway pressure in adults during the use of NHF (previous studies have
demonstrated positive airway pressure in healthy adult volunteers), which may have a number of potential clinical benefits
as seen with conventional pressure-generating devices. These include improved oxygenation, ventilation-perfusion
matching and reduced airway resistance which contribute to decreased work of breathing. Further clinical trials are
required to determine the extent to which NHF is associated with such benefits.
CONCLUSION:
NHF generates a significant low-level positive airway pressure in adults, in contrast to a traditional facemask. This may
have important clinical implications in improving respiratory support therapy.
KEY POINTS:
•
NHF generates a significant positive airway pressure in adult patients who have undergone elective cardiac surgery,
while a traditional facemask does not.
•
Significant positive airway pressure is generated by NHF when the mouth is open or closed.
•
Positive airway pressure generated by NHF may be associated with several clinical benefits including improved
oxygenation, ventilation perfusion matching and reduced WOB.
DELIVERY OF LOW LEVEL PO SITIVE AIR WAY PRESSURE (PARKE) | S9-P1
Page 21
R Parke, S McGuinness, M Eccleston
British Journal of Anaesthesia 2009 Dec; 103(6): 886-90
DEFINITIONS:
Absolute humidity
Continuous positive airway pressure
(CPAP)
Heated humidifier (HH)
Intensive care unit (ICU)
Nasal high flow therapy (NHF)
Work of breathing (WOB)
The amount of water vapour in a given volume of gas
A technique of respiratory therapy in which airway pressure is maintained
above atmospheric pressure throughout the respiratory cycle by
pressurization of the ventilatory circuit
A device which actively adds heat and water vapour to inspired gases
A hospital facility providing intensive nursing and medical care for
critically ill patients
A technique to provide a high flow of heated, humidified oxygen and air to
patients requiring respiratory support, delivered through nasal cannulae
The force required to expand the lung against its elastic properties
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
DELIVERY OF LOW LEVEL PO SITIVE AIR WAY PRESSURE (PARKE) | S9-P2
Page 22
N Groves, A Tobin
Australian Critical Care 2007; 20: 126-131
Nasal high-flow therapy delivers low level positive airway pressure
AIM:
To document airway pressures during the use of high-flow nasal (HFN) oxygen therapy under different gas flows and
breathing conditions to determine factors that influence the amount of positive expiratory pressure generated.
METHOD:
Ten volunteers (5 male, 5 female; mean age 33 years) were included in the study. Subjects were seated in an upright
position and had a catheter passed into the oropharynx via the nose to record pharyngeal pressure. Each was fitted with an
HFN interface (RT034; Fisher & Paykel Healthcare). Flow rates of 0-60 L/min were used, with the mouth open or closed;
inspired oxygen fraction was 0.21. Humidification was provided using a heated humidifier (MR850: Fisher & Paykel
Healthcare).
RESULTS:
Expiratory pharyngeal pressure (EPP) and inspiratory pharyngeal pressure (IPP) values are reported in the table.
EPP (cm H2O)
Mouth open
Mouth closed
IPP (cm H2O)
Mouth open
Mouth closed
a
0
10
Nasal flow rate (L/min)
20
40
60
0.3
0.8
0.7
1.7
1.4 a
2.9ab
2.2 ac
5.5 ac
2.7a
7.4 a
-0.6
-1.1
-0.2
-0.8
-0.2a
-0.2 a
0.1 a
1.1 ac
0.5 a
1.6 a
p< 0.05 vs 0 L/min; b p< 0.05 vs 10 L/min; c p< 0.05 vs 20 L/min.
Both EPP and IPP values increased as flow rates increased, when the mouth was open or closed (p< 0.001 for trend). EPP
values tended to be higher in female versus male subjects (p< 0.05 for mouth open comparison and p< 0.001 for mouth
closed). IPP values were significantly different between genders when the mouth was open (p< 0.05) but not when it was
closed. Linear regression analysis identified a number of significant associations: each 10 mL/min increase in flow rate
was associated with a 0.8 cm H2O increase in EPP (p< 0.001); each 10 cm increase in subject height was associated with a
0.5 cm H2O decrease in EPP (p< 0.05); male gender was associated with a 0.6 cm H2O decrease in EPP (p< 0.01); mouth
being closed was associated with a 2 cm H2O increase in EPP (p< 0.001).
DISCUSSION:
HFN therapy is associated with the generation of significant positive expiratory pressure. Important determinants of the
pressure generated are flow rate, gender, height and whether the mouth is open or closed. In patients with respiratory
failure, positive expiratory pressure is associated with a number of benefits, including improved ventilation/perfusion
matching, improved oxygenation, decreased airways resistance and reduced work of breathing. The benefits of HFN oxygen
therapy compared with noninvasive ventilation (NIV) include fewer pressure areas from tight-fitting face masks, improved
ease of communication, and easier oral care and intake.
CONCLUSION:
Significant expiratory positive pressure is generated during HFN oxygen therapy, which appears to be flow dependent.
Pressure is also strongly influenced by whether the mouth is open or closed, and by patient gender.
KEY POINTS:
• HFN oxygen therapy is capable of generating significant expiratory pressure, particularly at flow rates ≥20 L/min.
•
The benefits of expiratory pressure generated during HFN therapy are likely to be the greatest when high flow rates
are used and when patients breathe with their mouth closed.
•
These findings provide a good physiological basis by which HFN oxygen therapy may benefit patients over and
above increasing the inspired oxygen fraction.
•
HFN oxygen therapy may be a comfortable alternative to NIV, which required less patient co-operation while still
providing high levels of inspired oxygen and positive pressure.
GENERATION OF PO SITIVE AIR WAY PRESSURE IN ADULT VOL UNTEERS (GROVES) | S10-P1
Page 23
N Groves, A Tobin
Australian Critical Care 2007; 20: 126-131
DEFINITIONS:
Heated humidifier
Noninvasive ventilation (NIV)
A device that actively adds heat and water vapour to inspired gas
The delivery of ventilatory support without the need for an invasive
artificial airway
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
GENERATION OF PO SITIVE AIR WAY PRESSURE IN ADULT VOL UNTEERS (GROVES) | S10-P2
Page 24
A Hasani, TH Chapman, D McCool, RE Smith, JP Dilworth, JE Agnew
Chronic Respiratory Disease 2008; 5: 81-6
Domiciliary humidification improves lung mucociliary clearance in patients with bronchiectasis
AIM:
To determine the effects of heated humidification therapy on mucociliary clearance in patients with bronchiectasis.
METHOD:
Fourteen subjects with bronchiectasis confirmed by high resolution computed tomography entered the study. Four
withdrew during the screening phase; leaving ten patients for treatment and analysis (mean age 63 years). Humidification
therapy was provided by an MR880 heated humidifier (Fisher & Paykel Healthcare). The system provided air at 37 °C and
fully saturated with water vapour (100% relative humidity) via nasal cannula at a flow rate of 20-25 L/min. Patients were
instructed to use humidification therapy for 3 hours as an acute treatment, then for 3 hours each day for 6 days as a short
term treatment. Patient compliance was recorded automatically as patients used the system (usage time of the blower
supplying the humidifier with air was recorded). Assessments were performed at baseline and after treatment; these
included lung function (assessed by a spirometer) and tracheobronchial clearance as a measure of mucociliary clearance
assessed using a radioaerosol technique.
RESULTS:
Nine out of ten patients used humidification for longer than the target study treatment duration of 21 hours; median
duration of humidification was 25.0 hours (range 14.9 to 26.9). All patients successfully used the humidification system
and rated it as very acceptable. Tracheobronchial clearance (mucociliary clearance) was significantly improved by
humidification therapy, as shown by significant improvements in radio-aerosol movement. There was a nonsignificant
reduction in the number of coughs after short-term humidification therapy, and lung function parameters also tended to
improve compared with baseline.
DISCUSSION:
Mucociliary clearance is the first-line defense mechanism in the upper and lower airways. Patients with bronchiectasis
have lung mucous retention and experience a high rate of respiratory infection. Effective mucociliary clearance has been
shown to be dependent on sufficient airway surface liquid volume. The improvement in mucociliary clearance seen in this
study after heated humidification therapy in patients with bronchiectasis for three hours per day has the potential to
decrease the risk of respiratory infection and disease exacerbations, and thus slow the rate of disease progression. Further
studies are required to see whether the short-term benefits observed in this study persist during longer term therapy.
CONCLUSION:
Humidification therapy appears to have a protective effect in patients with bronchiectasis by improving mucociliary
clearance.
KEY POINTS:
• Providing inspired air at 37 °C and fully saturated with water vapour (100% relative humidity) via nasal cannula at a
flow rate of 20-25 L/min for three hours per day significantly improves mucociliary clearance in patients with
bronchiectasis.
•
Improved mucociliary clearance in patients with bronchiectasis has the potential to decrease the rate of respiratory
infections and may therefore slow the rate of disease progression.
DEFINITIONS:
Bronchiectasis
100% relative humidity (RH)
Computed tomography
Radio-aerosol movement
Tracheobronchial clearance
A chronic inflammatory or degenerative disease of the bronchi which
causes localized, irreversible dilation of part of the bronchial tree,
resulting in airflow obstruction and impaired mucous clearance
The maximum amount of water a gas can hold at a given temperature
Three-dimensional medical imaging
Reflects the rate of clearance of inhaled radio-aerosol particles from the
lung
Particle clearance from the ciliated conducting airways (tracheobronchial
region)
Independently produced by Wolters Kluwer Health - Adis International Ltd
World leaders in impartial pharmacoevaluation
HUMIDIFICATION AN D LUNG MUCO CILIARY CLEARANCE (HASSANI) | S11-P1
Page 25
RL Parke, ML Eccleston, SP McGuinness
Respiratory Care 2011; 56(8): 1151-5
The effects of flow on airway pressure during nasal high-flow oxygen therapy
AIM:
To determine the relationship between air flow from nasal high-flow oxygen therapy (NHF) and mean nasopharyngeal
airway pressure in adults.
METHOD:
Adult patients undergoing cardiac surgery were recruited to participate in this prospective, observational, single centre
study (n=15). After surgery, patients were fitted with a 10 French catheter into the nasopharynx via the nose while
sedated and ventilated in the intensive care unit. The morning after surgery, once the patient was awake, extubated and
sitting upright, the catheter was connected to a pressure transducer and NHF was begun using a heated humidified NHF
system [Optiflow™; Fisher & Paykel Healthcare]. After an acclimatisation period of 15 min and once breathing had
settled, 1 min recordings of nasopharyngeal airway pressure were taken with the patient’s mouth both open and closed
at flow rates of 30, 40 and 50 L/min. Each patient received NHF at each flow rate according to a standard method of
random allocation.
Mean nasopharyngeal airway pressure was the average of pressures from the peak of inspiration of the first breath to
the peak of inspiration of the last breath of each 1 min recording.
RESULTS:
Twelve patients completed the study. As NHF flow rate increased, airway pressure increased in a positive linear manner,
in both the mouth-open and mouth-closed positions. At each flow rate, airway pressure was significantly greater in the
mouth-closed position than the mouth-open position (table).
NHF flow rate
(L/min)
30
40
50
Mean (SD) nasopharyngeal airway pressure (cm H2O)
Mouth closed
Mouth open
1.93 (1.25)
2.58 (1.54)
3.31 (1.05)
1.03 (0.67)
1.30 (0.80)
1.73 (0.82)
P value
0.046
0.03
<0.001
NHF = nasal high-flow oxygen therapy; SD = standard deviation.
DISCUSSION:
There are currently few data regarding airway pressure generated by NHF and the relationship between flow rate and
resultant airway pressure. This study found that mean nasopharyngeal pressure during NHF with Optiflow increases
as flow rate increases. NHF generates positive airway pressure, and this pressure is greater when the mouth is closed.
This latter observation could potentially be explained by higher pressure when the mouth is closed, presumably due to
higher resistance to expiration since the expired gas is forced to flow via a restricted path. Higher airway pressure was
also observed during inspiration, which could be attributed to pressure in the upper airway being above atmospheric
pressure because of the high velocity of incoming gas.
Inter-patient variability in airway pressure was noted in this study, as in previous studies, and this was likely due to
variations between patients in nare size relative to nasal interface size. Clinicians prescribing NHF should be aware of
this.
Although NHF cannot yet be considered as an alternative to continuous positive airway pressure (CPAP), it could be used
as an interim treatment step in selected patients, particularly given its advantages over high-flow face-mask oxygen
therapy (HFFM), which include better comfort, improved oxygenation and lower respiratory rates.
CONCLUSION:
In this study of NHF (OptiflowTM) for adults after cardiac surgery, there was a positive linear correlation between flow rate
and nasopharyngeal airway pressure.
KEY POINTS:
• Airway pressure is significantly positively correlated with the oxygen flow rate when using NHF in adults.
•
A positive airway pressure is generated, and airway pressure is higher with the mouth closed than with the mouth
open.
•
There may be inter-patient variability in airway pressure in patients using NHF.
THE EFFECT S OF FLOW ON AIRWAY PRESSURE (PARKE) | S12-P1