Optiflow Infant Nasal High Flow Clinical Paper Summaries Rev C

Page 1

Adult Nasal High Flow: Clinical Paper Summaries

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

Page 4

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

Page 5

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

Page 6

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

Page 7

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

Page 9

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