800 Series Ventilator System Operator’s Manual Addendum Rev A PAV+ option

PAV+ option

Intended use PAV+ is intended for use in spontaneously breathing adult patients whose ventilator ideal body weight (IBW) setting is at least 25.0 kg. Patients must be intubated with either endotracheal (ET) or tracheostomy (Trach) tubes of internal diameter (I.D.) 6.0 mm to 10.0 mm. Patients must have satisfactory neuralventilatory coupling, and stable, sustainable inspiratory drive. Warning •

Do not use PAV+ in non-invasive ventilation applications.

•

Breathing circuit and ET tube cuff must be free from leaks. Leaks may result in over-assist and patient discomfort.

Overview The act of inspiration requires the patient’s inspiratory muscles to develop a pressure gradient between the mouth and the alveoli sufficient to draw in breathing gas and inflate the lungs. Some of this pressure gradient is dissipated as gas travels through the artificial airway and the patient’s conducting airways, and some of the pressure gradient is dissipated in the inflation of the lungs and thorax. Each element of pressure dissipation is characterized by a measurable property: the resistance of the artificial and patient airways, and the compliance (or elastance) of the lung and thorax. PAV+ software uses specific information, including resistance of the artificial airway, resistance of the patient’s airways, lungthorax compliance, instantaneous inspiratory flow and lung volume, and the % Support setting to compute the instantaneous pressure to be applied at the wye. PAV+ software randomly estimates patient resistance and compliance approximately every four to ten breaths. Every 5 milliseconds (ms), the software estimates lung flow, based on an estimate of wye flow, and lung volume, based on the integral value of estimated wye flow. The PA breath begins inspiratory assist when flow (generated by the patient’s inspiratory muscles) appears at the wye. If the patient ceases inspiration, the assist also ceases. Once inspiratory

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PAV+ option flow begins, PAV+ software monitors instantaneous flow and volume every 5 ms and applies the pressure calculated to overcome a proportion (determined by the % Support setting) of the pressure losses dissipated across the resistances of the artificial and patient airways and lung/thorax compliance. Because the PAV+ algorithm does not know the patient’s mechanics when the PA breath type is selected, the software performs a startup routine to obtain initial data. At startup, PAV+ software delivers four consecutive PA breaths, each of which includes an end-inspiratory maneuver that yields estimates of the patient’s resistance and compliance. The first breath is delivered using the predicted resistance for the artificial airway and conservative estimates for patient resistance and compliance, based on the patient’s IBW. Each of the following three PA breaths averages stepwise decreased physiologic values with the estimated resistance and compliance values from the previous breath, weighting earlier estimates less with each successive breath, and yielding more reliable estimates for resistance and compliance. The fifth PA breath (the first non-startup breath) is delivered using the final estimates with the clinician-set % Support setting. Once startup is complete, the PAV+ software randomly applies a maneuver breath every four to ten breaths after the last maneuver breath to reestimate patient resistance and compliance. New values are always averaged with former values. The PAV+ option graphically displays estimates of patient lung pressure (intrinsic PEEP), patient compliance, patient resistance, total resistance, total work of inspiration, patient work of inspiration, inspiratory elastic work (an indicator of lung-thorax work), and inspiratory resistive work. The % Support setting ranges from a minimum of 5% (the ventilator performs 5% of the work of inspiration and the patient performs 95%) to a maximum of 95% (the ventilator performs 95% of the work and the patient performs 5%), adjustable in 5% increments. The PAV+ option also includes alarm limits, safety checks, and logic checks that reject non-physiologic values for patient resistance and compliance and inappropriate data.

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PAV+ option To maintain accurate compliance compensation and spirometry, and for optimal breath delivery, the humidification type and volume can be adjusted after running SST. Warning Ensure that there are no large leaks in the breathing circuit or around the endotracheal (ET) tube cuff. Large leaks can affect the performance of the PAV+ option and the accuracy of resistance (R) and elastance (E) estimates.

NOTE: For optimal performance, do not use silicone breathing circuits with the PAV+ option: the elastic behavior of a silicone circuit at the beginning of exhalation can cause pressure-flow oscillations that result in underestimates of patient resistance.

Setting up PAV+ Follow the steps below to apply PAV+ from the New Patient set up screen or current ventilation screens as indicated. (For more information on ventilator settings, see 840 Operator’s and Technical Reference Manual.): Applying PAV+ settings from:

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New Patient set-up screen

Current ventilation screen

1. Run or ensure that Short Self Test (SST) has been run with an adult-size circuit. When SST is complete, the ventilator automatically transitions from SST to the New Patient set-up screen.

1. Ensure that the patient is being ventilated with an adult-size breathing circuit.

2. Touch the New Patient set-up button.

2. Touch the VENT SETUP button on the lower screen.

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PAV+ option Applying PAV+ settings from: New Patient set-up screen 3. Verify that you are using an ADULT circuit, and enter the patient’s body weight by touching the IBW button and turning the knob to the desired weight setting.

Current ventilation screen 3. Proceed to Step 5.

4. Touch the CONTINUE button. 5. Touch the MODE button. 6. Turn the knob to select SPONT mode. 7. Touch the SPONTANEOUS TYPE button. 8. Turn the knob to select PA (proportional assist breath type). Note that for the PA breath type to be available: • The patient’s IBW must be at least 25 kg • The tube I.D. must be at least 6.0 mm 9. Touch the CONTINUE button. Default settings applicable to SPONT and PA appear in the Sandbox portion of the lower screen.

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PAV+ option Applying PAV+ settings from: New Patient set-up screen

Current ventilation screen

10. Touch the button for each setting you want to change, then turn the knob to set the desired value. Proposed changes are highlighted in contrasting colors. If PA is a new selection, the TUBE TYPE and TUBE I.D. buttons flash until you touch them. When making settings, verify the following: • Type of artificial airway: ET (endotracheal) or TRACH (tracheostomy) • Tube I.D.: 6.0 mm to 10.0 mm according to tube size in use • ESENS value: 3 L/min (default). Although ESENS is adjustable between 1 L/min and 10 L/min, do not change unless indicated. • Appropriate % Support level

NOTE: • When selecting the appropriate % Support level, consider the

following during initial setup and subsequent adjustments: - Wait a minimum of 10–15 breaths for the algorithm to stabilize to the patient’s response to the new % Support setting before making other settings changes. - Higher levels of support may prove uncomfortable to the patient, which may result in increased agitation. Be cautious when choosing % Support values higher than 80%. - Use the work of breathing (WOB) graph as a guide. See “Graphics displays in PAV+” on page 20 and “WOB Terms and Definitions” on page 21 for more information. Adjust the % Support setting to maintain the patient’s WOB (WOBPT) within the “green” region. If the WOBPT indicator is to the left or the right of the green region, the patient is being, respectively, over-supported or under-supported by the ventilator. • These suggestions should not replace sound clinical practice.

11. Press ACCEPT to apply the new settings, or the VENT SETUP button to cancel the changes.

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PAV+ option Once PAV+ is applied, the message PAV STARTUP flashes in the upper right corner of the upper waveforms subscreen while software makes an initial determination of patient resistance and compliance. Calculation and display of work of breathing (WOBPT) and intrinsic PEEP (PEEP I) occur after PAV STARTUP is complete. NOTE: PAV+ uses only the % Support setting, which can be adjusted up or down at any time. If the % Support setting is decreased, the new setting becomes effective at the next inspiration. If the % Support setting is increased by more than 10%, the change becomes effective in increments of 10% at every other breath. During this transition, the work of breathing graphic may show changes that continue until the actual % Support equals the set value and the patient adjusts to the new % Support setting.

Adjust apnea parameters After accepting the PAV+ settings, the ventilator displays the Apnea Setup screen. Adjust the Apnea parameters as required.

Adjust alarm settings The PAV+ option includes the high inspired spontaneous tidal volume alarm (2VTI SPONT) and low exhaled spontaneous tidal volume alarm (4VTE SPONT) limit settings (see Table 2 on page 10). NOTE: Because of the breathing variability that PAV+ allows, the 3VTE SPONT alarm, by default, is turned OFF to minimize nuisance alarms. To monitor adequate ventilation, use the 3VE TOT alarm instead. Follow these steps to adjust alarm settings: 1. Touch the ALARM SETUP button on the lower screen to view the current alarm settings. The buttons to the right of each bar show the alarm limits. 10011698 Rev. A (04/06)

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PAV+ option 2. Touch the button for each alarm limit you want to change. 3. Turn the knob to adjust the value of the alarm limit. Proposed values are highlighted. You can change more than one alarm limit before applying the changes. 4. Press ACCEPT to apply the changes or the ALARM SETUP button to cancel.

Adjust tube type, tube I.D., and humidification type Follow these steps to select new settings for the tube and humidifier without having to return to VENT SETUP: 1. Touch the OTHER SCREENS button MORE SETTINGS button.

, then touch the

2. Touch the button for the setting you are changing (Humidification Type, Tube I.D., or Tube Type). For non-HME humidification types, touch the Humidifier Volume button, then turn the knob to adjust the (empty) humidifier volume. 3. Press ACCEPT to apply the new settings, or the OTHER SCREENS button to cancel. NOTE: Although the PAV+ option allows you to change humidification type and humidifier volume without re-running SST, the accuracy of PA breaths and spirometry measurements is not ensured unless you perform SST using the intended circuit. Clinicians are strongly advised to run SST using the intended circuit.

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PAV+ option PAV+ ventilator settings Table 1 summarizes the ventilator settings that are applicable to the PAV+ option. Table 1: PAV+ settings Setting

Function

Range, new patient value, resolution

% Support

Sets the level of PAV+ support supplied by the ventilator. A setting of 95% means that the ventilator supplies 95% of the work of inspiration, while the patient supplies only 5%.

Range: 5 to 95% New patient: 50% Resolution: 5%

Expiratory sensitivity (E SENS)

Sets the flow at which the ventilator cycles from inspiration to exhalation for PA breaths.

Range: 1 to 10 L/min New patient: 3 L/min Resolution: 1 L/min

Humidifier volume (except when HME is selected)

Adjusts the empty volume of the humidifier chamber in use.

Range: 100 to 1000 mL New patient: 480 mL (default) Resolution: 10 mL

Tube type

Selects endotracheal (ET) or tracheostomy (Trach) tube.

Range: Trach or ET New patient: ET

Tube I.D.

Selects the internal diameter of the tube from a range of recommended sizes based on IBW. (Table 6 on page 18 lists IBW ranges and corresponding tube I.D. ranges.) Recommended ranges can be overridden. See “Tube internal diameters” on page 18.

Range: 6.0 mm to 10.0 mm New patient: Based on IBW Resolution: 0.5 mm

Trigger type

Determines how inspirations are detected.

Range: Flow or pressure New patient: Flow

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PAV+ option PAV+ alarm settings Table 2 summarizes the alarm settings that are available when the PAV+ option is active. Table 2: Alarm settings Setting High inspired spontaneous tidal volume limit (2VTI SPONT)

Function

Range: 35 to 6000 mL Sets the maximum inspired (5.0 mL/kg x IBW to 45.7 volume limit at which the mL/kg x IBW) ventilator truncates inspiration and cycles into exhalation. New patient: 15.0 mL/kg x IBW Applicable to PA or tube Resolution: 1 mL for 35 to 99 mL compensated (TC) 5 mL for 100 to 395 mL spontaneous breath types 10 mL for 400 to 6000 only. Recommended value less mL than 20.0 mL/kg x IBW.

Low exhaled Sets the minimum exhaled spontaneous tidal spontaneous tidal volume volume limit alarm threshold. (4VTE SPONT)

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Range, resolution, accuracy

Range: 1 to 2500 mL New patient: OFF Resolution: 1 mL for 1 to 100 mL; 5 mL for 100 to 400 mL; 10 mL for 400 to 2500 mL

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PAV+ option Monitored data Table 3 lists the monitored data associated with the PAV+ option. Table 3: PAV+ monitored data Data

CPAV (PAV-based lung compliance) *

EPAV (PAV-based lung elastance) *

Function

Range, resolution, accuracy

The change in pulmonary volume for an applied change in patient airway pressure when measured under conditions of zero flow, estimated during a PAV+ plateau maneuver. When PA is selected, the ventilator displays the current filtered value for patient compliance, and updates the display at the successful completion of each estimation. The value is displayed in the More Patient Data and Waveforms screens.

Range: 2.5 to 200 mL/cmH2O Resolution: 0.1 mL/cmH2O for values < 10 mL/cmH2O 1 mL/cmH2O for values ≥ 10 mL/cmH2O Accuracy: ± (1 + 20% of actual) mL/cmH2O

EPAV is calculated as the

Range: 5.0 to 400 cmH2O/L Resolution: 0.1 cmH2O/L for values < 10 cmH2O/L 1 cmH2O/L for values ≥ 10 cmH2O/L Accuracy: ± (1 + 20% of actual) cmH2O/L

inverse of PAV-based lung compliance. See C PAV function above.

* If the estimated value of C PAV, E PAV, R PAV, or R TOT violates expected (IBW-based) limits, parentheses around the value indicate that the value is questionable. If the estimated value exceeds its absolute limit, the limit value flashes in parentheses.

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PAV+ option Table 3: PAV+ monitored data (continued) Data

PEEPI (intrinsic PEEP)

RPAV (PAV-based patient resistance)*

Function

Range, resolution, accuracy

The estimated positive pressure above PEEP remaining the lungs at the end of exhalation. When PA is selected, the ventilator displays the current estimated value for intrinsic PEEP once PAV+ setup is complete, and updates the display at the successful completion of each estimation. Displayed in the More Patient Data and Waveforms screens.

Range: 0 to 130 cmH2O Resolution: 0.1 cmH2O for values < 10 cmH2O 1 cmH2O when ≥ 10 cmH2O Accuracy: Not applicable

The difference between estimated total resistance (RTOT) and the resistance of the artificial airway. When PA is selected, the ventilator displays the current filtered value for patient resistance, and updates the display at the successful completion of each estimation. Displayed in the More Patient Data and Waveforms screens.

Range: 0.0 to 20 cmH2O/L/s Resolution: 0.1 cmH2O/L/s for values < 10 cmH2O/L/s 1 cmH2O/L/s for values ≥ 10 cmH2O/L/s Accuracy: Not applicable

* If the estimated value of C PAV, E PAV, R PAV, or R TOT violates expected (IBW-based) limits, parentheses around the value indicate that the value is questionable. If the estimated value exceeds its absolute limit, the limit value flashes in parentheses.

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PAV+ option Table 3: PAV+ monitored data (continued) Data

Function

Range, resolution, accuracy

RTOT (estimated total resistance)*

The estimated fraction of pressure/flow for the patient airways and ventilator breathing system together at the peak exhalation flow. When PA is selected, the ventilator displays the current filtered value for total resistance, and updates the display at the successful completion of each calculation. Displayed in the More Patient Data screen.

Range: 1.0 to 20 cmH2O/L/s Resolution: 0.1 cmH2O/L/s for values < 10 cmH2O/L/s 1 cmH2O/L/s for values ≥ 10 cmH2O/L/s Accuracy: ± (3 + 20% of actual resistance) cmH20/L/s from 5 to 80 cmH2O/L/s when RPAV < 60 cmH2O/L/s

VTI SPONT (Spontaneous inspired tidal volume)

Displays the BTPS value for inspired tidal volume. Updated at the beginning of the following expiratory phase.

Range: 0 to 6000 mL Resolution: 1 mL for 0 to 6000 mL Accuracy: For TI ≥ 200 ms and < 600 ms, ± (10 + 10%* 600 ms/TI ms of reading) mL; otherwise, ± (10 + 10% of reading) mL

f/VT/kg [Normalized rapid shallow breathing index (RSBI)]

Displays the normalized fraction of respiratory rate to inspired volume measurements on the More Patient Data screen. Available for PA breaths only. Normalizing f/VT minimizes the variation in RSBI due to variation in VT due to IBW.

Range: 0 to 24 1/min-L/kg Resolution: 0.1 when f/VT/kg < 10; 1 when f/VT/kg ≥ 10 Accuracy: Not applicable

* If the estimated value of C PAV, E PAV, R PAV, or R TOT violates expected (IBW-based) limits, parentheses around the value indicate that the value is questionable. If the estimated value exceeds its absolute limit, the limit value flashes in parentheses.

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PAV+ option Table 4 lists the IBW-based absolute limits for PAV+ option monitored data. Table 4: Absolute limits for PAV+ monitored data IBW (kg/lb)

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RPAV (cmH2O/L/s)

CPAV (mL/cmH2O)

EPAV (cmH2O/L)

25 / 55.1

0 to 20

2.5 to 29

34 to 400

35 / 77.1

0 to 20

3.5 to 41

24 to 286

45 / 99.1

0 to 20

4.5 to 52

19 to 222

55 / 121.1

0 to 20

5.5 to 64

16 to 182

65 / 143.2

0 to 20

6.4 to 75

13 to 156

75 / 165.2

0 to 18

7.4 to 87

11 to 135

85 / 187.2

0 to 17

8.4 to 98

10 to 119

95 / 209.3

0 to 16

9.4 to 110

9.1 to 106

105 / 231.3

0 to 15

10 to 121

8.3 to 100

115 / 253.3

0 to 15

11 to 133

7.5 to 91

125 / 275.3

0 to 14

12 to 144

6.9 to 83

135 / 297.4

0 to 14

13 to 156

6.4 to 77

145 / 319.4

0 to 14

14 to 167

6.0 to 71

150 / 330.4

0 to 14

15 to 173

5.8 to 67

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Alarms Table 5 summarizes the alarms associated with the PAV+ option. Table 5: PAV+ alarms Base message

1PPEAK

↑PVENT

Analysis message

Remedy message

Comments

Low

Last breath ≥ set limit.

Medium

Last 3 breaths ≥ set limit.

Check patient circuit & ET tube.

High

Last 4 or more breaths ≥ set limit.

Violation of high inspiratory pressure limit: estimated airway pressure ≥ set 2PPEAK. When detected, ventilator truncates current breath unless already in exhalation. Possible dependent alarms: VE TOT, 1fTOT. Corrective action: Check patient. Check for leaks, tube type/I.D. setting. Consider reducing % Support setting or increasing 2PPEAK.

Low

1 breath ≥ limit. Check patient circuit & ET 2 breaths ≥ tube. limit.

Inspiratory pressure ≥ 100 cmH2O. Ventilator truncates current breath unless already in exhalation. This alarm is unlikely when PAV+ is active. Possible dependent alarms: 3VE TOT, 1fTOT Corrective action: Check patient for agitation. Agitated breathing, combined with high % Support, can cause over-assistance. Consider reducing % Support setting.

Urgency

Medium High

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3 or more breaths ≥ limit.

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PAV+ option Table 5: PAV+ alarms (continued) Base message PAV STARTUP TOO LONG

PAV R & C NOT ASSESSED

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Analysis message

Remedy message

Comments

Low

PAV startup not complete for ≥ 45 s.

Medium

PAV startup not complete for ≥ 90 s.

Check for leaks, shallow breathing, & settings for 1VTI SPONT, 1PPEAK.

High

PAV startup not complete for ≥ 120 s.

PAV+ unable to estimate initial valid values for R and C. Possible dependent alarms: 3VTE SPONT, 3VE TOT, 1fTOT. Corrective action: Check patient (patient’s inspiratory times may be too short to evaluate resistance and compliance). Check that selected humidification type and empty volume are correct.

Low

R and/or C ≥ 15 minutes old.

Medium

R and/or C ≥ 30 minutes old.

Check for leaks, shallow breathing, & settings for the tube I.D., 1VTI SPONT, 1PPEAK.

Startup was successful, but later assessments were unsuccessful. Corrective action: Check patient (patient’s inspiratory times may be too short to evaluate resistance and compliance). Check that selected humidification type and empty volume are correct.

Urgency

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PAV+ option Table 5: PAV+ alarms (continued) Base message

1VTI SPONT

Urgency

Analysis message

Low

Last spont breath ≥ set limit.

Medium

Last 3 spont breaths ≥ set limit.

High

Last 4 or more spont breaths ≥ set limit.

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Remedy message

Comments

Check for leaks, tube type/I.D. and %Support settings, and patient agitation.

High inspired tidal volume. Delivered inspiratory volume ≥ inspiratory limit. Ventilator transitions to exhalation. Possible dependent alarms: 1fTOT Corrective action: Check for patient agitation, which can cause miscalculation of RPAV and CPAV. Consider reducing % Support setting. Check 2VTI.

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Tube internal diameters Table 6 lists ideal body weights and corresponding estimated tube internal diameters. If you select an internal diameter that does not match the IBW range, you must touch the OK button to confirm that you want to override the estimated range. Table 6: IBW and tube I.D. ranges

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ET/Trach I.D. (mm) ET/Trach I.D. (mm) (low) (high)

IBW (kg)

IBW (lb)

25-27

54-60

6.0

6.5

28-35

61-77

6.0

7.0

36

78-79

6.0

7.5

37-42

80-93

6.5

7.5

43-49

94-108

6.5

8.0

50

109-117

7.0

8.0

55

118-130

7.0

8.5

60

131-132

7.0

9.0

65

133-152

7.5

9.0

70

153-154

7.5

9.5

75

155-174

8.0

9.5

80-100

175-231

8.0

10.0

110-135

232-296

8.5

10.0

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PAV+ option Table 6: IBW and tube I.D. ranges (continued) IBW (kg)

IBW (lb)

140-150

297-330

ET/Trach I.D. (mm) ET/Trach I.D. (mm) (low) (high) 9.0

10.0

NOTE: Ensure that the correct artificial airway I.D. size is entered. Because PAV+ amplifies flow, entering a smaller than actual airway I.D. causes the flow-based pressure assistance to oversupport the patient and could lead to transient flow runaway at high values of % Support. Conversely, entering a larger than actual I.D. results in under-support. PAV+ software monitors the settings for the IBW and artificial airway. If the settings differ from the above ranges, you must confirm that the settings are correct. Confirming or correcting the actual I.D. size minimizes the likelihood that PAV+ will over-support or under-support.

Ventilator settings/guidelines Warning For optimal performance of PAV+, it is important to select the humidification type, tube type, and tube size that match those in use on the patient. The instantaneous wye pressure generated during inspiration is a function of the patient effort, % Support setting, tube type and size, patient resistance and elastance, and the instantaneously measured gas flow and lung volume. Set 2P PEAK to a safe circuit pressure, above which truncation and alarm annunciation are appropriate.

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PAV+ option

NOTE: PAV+ has a built-in high pressure compensation (1PCOMP) limit that is determined by the 2P PEAK setting minus 5 cmH2O or 35 cmH2O, whichever is less. If the inspiratory pressure at the circuit wye (Piwye) reaches the 1PCOMP limit, the inspiration is truncated, and the ventilator transitions to exhalation. Refer to page 27 for more details.

Specified performance Performance using the PAV+ option is ± 0.5 joules/liter (imposed work during inspiration at the 75% support level). In ventilation terms, work is expressed as:

Work [Joules / L ] =

[

]

Joules ∗ ∫ Pressuret [cmH 2O ]∗ Flowt [Ls ]∗ dt [s ] 0.098 cmH 2 O* L

∫ Flow [ ]∗ dt[s] L t s

Graphics displays in PAV+ When the PAV+ option is active (the mode is SPONT and the spontaneous breath type is PA), a work of breathing (WOB) graphic is automatically displayed (Figure 1 on page 22), which shows: •

estimates of work of breathing relative to normal, subnormal, and above-normal values, including: − the estimated patient work of breathing (in Joules/L) during inspiration (WOBPT) and − the estimated total work of breathing (in Joules/L) of the patient and ventilator during inspiration (WOBTOT).

•

an indicator that shows the proportion of patient inspiratory work to overcome the elastance (E) and resistance (R) of the system.

Additional information in the graphics screen includes: •

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a “shadow” trace of the estimated lung pressure, which is shown as a solid area superimposed on the circuit pressure waveform. 10011698 Rev. A (04/06)