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

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BiLevel option/800 Series Ventilators

Setting up BiLevel BiLevel is a ventilatory mode (along with A/C, SIMV, and SPONT). To select BiLevel during normal ventilation, follow these steps: 1. Touch the SETUP button on the lower screen. 2. Touch the Mode button, then turn the knob to display BILEVEL. Once you select BiLevel mode, the PC mandatory breath type is automatically selected and cannot be changed. You can select PS or none as the spontaneous type, and you can select either trigger type (P-TRIG or V. -TRIG). Once you’ve made the setup changes, touch CONTINUE. 3. The applicable settings for BiLevel mode are displayed. For each setting you want to change, touch its button and turn the knob to set its value. PEEPH must always be at least 5 cmH2O greater than PEEPL. The flow acceleration % setting determines the rise time to reach target pressure for transitions from PEEPL to PEEPH and spontaneous breaths, even when pressure support (PSUPP) = 0. Expiratory sensitivity (ESENS ) applies to all spontaneous breaths. You can set the PEEPL time (TL ), the PEEPH time (TH ), or the ratio of TH to TL. To select settings that would result in a TH:TL ratio greater than 4:1, you must touch the OK button to confirm after reaching the 4:1 limit. 4. Once you've made any changes you want, press ACCEPT to apply the new settings.

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Using pressure support with BiLevel Spontaneous breaths in BiLevel mode can be assisted with pressure support (see Figure 2) according to these rules: •

Pressure support (PSUPP) can be used to assist spontaneous breaths at PEEPL and PEEPH. PSUPP is always set relative to PEEPL. Target pressure = PEEPL + PSUPP.

•

Spontaneous patient efforts at PEEPH are not pressure supported unless PSUPP > (PEEPH - PEEPL ). All spontaneous breaths (whether or not they are pressure supported) on 800 Series Ventilators are assisted by a pressure of 1.5 cmH2O.

•

If PSUPP + PEEPL is greater than PEEPH + 1.5 cmH2O, all spontaneous breaths at PEEPL are assisted by the PSUPP setting, and all spontaneous breaths at PEEPH are assisted by PSUPP (PEEPH - PEEPL ). For example, if PEEPL = 5 cmH2O, PEEPH = 15 cmH2O, and PSUPP = 20 cmH2O:

- All spontaneous breaths at PEEPL are assisted by 20 cmH2O of pressure support (PEEPL + PSUPP) for a total pressure of 25 cmH2O, and - All spontaneous breaths in PEEPH are assisted by 10 cmH2O of pressure support (PSUPP - (PEEPH - PEEPL )) for the same total pressure of 25 cmH2O.

25 20

PEEPH

PEEPH pressure support = 10 cmH2O

PEEPL Pressure support = 20 cmH2O

15 10 5 PEEPL

Pressure Time

8-00311

Figure 2. BiLevel with pressure support

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BiLevel option/800 Series Ventilators

Manual inspirations in BiLevel mode Pressing the MANUAL INSP key during BiLevel mode causes the ventilator to: •

Cycle to PEEPH, if the current PEEP level is PEEPL.

•

Cycle to PEEPL, If the current PEEP level is PEEPH.

To avoid breath stacking, the ventilator does not cycle from one PEEP level to another during the earliest stage of exhalation.

Specifications Low PEEP (PEEPL )

Range: 0 to 45 cmH2O. Resolution: PEEPL from 0 to 20 cmH2O: 0.5 cmH2O. PEEPL from 21 to 45 cmH2O: 1 cmH2O. PEEPL must be at least 5 cmH2O less than PEEPH.

High PEEP (PEEPH )

Range: 5 to 90 cmH2O. Resolution: 1 cmH2O for all levels of PEEPH. PEEPH must be at least 5 cmH2O greater than PEEPL, and at least 2 cmH2O less than the ­PCIRC limit.

Low PEEP time (TL )

Range: > 0.2 second. Resolution: 0.01 second.

High PEEP time (TH ) Range: > 0.2 to 30 seconds. Resolution: 0.01 second. Ratio of PEEPH time to PEEPL time (TH:TL )

Range: 1:299 - 149:1 Resolution: 1 for TH:TL ratios > 100:1 and < 1:100. 0.1 for TH:TL ratios from < 99.9:1 to 10.0:1 and 1:10.0 to > 1:99.9. 0.01 for TH:TL ratios from < 9.99:1 to > 1:9.99.

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Technical description BiLevel is the only mode of ventilation that cycles between two operator-specified levels of PEEP. BiLevel’s mandatory breathing pattern is controlled by a pressure-based algorithm similar to A/C mode with PC breath type selected. However, in BiLevel the patient is free to initiate spontaneous breaths at both PEEP levels. Because both mandatory and spontaneous breaths are available, BiLevel (like SIMV) is classified as a mixed mode. At conventional settings and in the absence of spontaneous breathing, both BiLevel and SIMV (with PC breath type selected) resemble A/C mode with PC breath type selected. By setting PEEPH, TH, and respiratory rate (f) close to the patient's normal values, BiLevel looks just like A/C. As you decrease the f setting, BiLevel looks more like SIMV, with spontaneous breaths following mandatory breaths. If you set f to 4 to 8 breaths per minute and shorten TL so that it is just long enough to allow full or near-full exhalation, BiLevel resembles airway pressure release ventilation (APRV). BiLevel looks less like any of these modes when the f setting is well below the patient's spontaneous rate and the TH:TL ratio is between 2:1 and 1:2. Within this range of I:E ratios, the ventilator cycles between PEEPH and PEEPL, and the TH and TL intervals each last several seconds. Spontaneous efforts that trigger the ventilator appear as CPAP or pressure-supported breaths. You can think of BiLevel as a combination of two A/C routines: one at PEEPH and one at PEEPL. Each routine has a way to cycle from one PEEP level to the other, to respond to spontaneous inspirations, to calculate pressure support, to synchronize transitions between PEEP levels with the patient's breathing, and to transition into and out of BiLevel mode. Over the course of a breath interval, BiLevel cycles the ventilator between the two PEEP levels (PEEPH and PEEPL ). The durations of PEEPH and PEEPL are defined by the variables TH and TL. BiLevel attempts to synchronize the transition from one PEEP level to the other with the patient's breathing pattern.

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BiLevel option/800 Series Ventilators Once breathing begins, these intervals can shorten or lengthen to synchronize with the patient's inspiratory or expiratory efforts. To synchronize BiLevel with the patient's breathing, TH and TL are each partitioned into spontaneous and synchronous intervals (see Figure 3). TH

TL PEEPH

Pressure PEEPL Time Spontaneous interval

Synchronous interval

Spontaneous interval

Synchronous interval 8-00312

Figure 3. Spontaneous and synchronous intervals in BiLevel mode By partitioning TH and TL into spontaneous and synchronous phases, BiLevel responds to patient efforts (or lack of them) in a predictable pattern: •

During the spontaneous interval of each PEEP level, successful inspiratory efforts cause the ventilator to deliver spontaneous breaths (although no spontaneous efforts are necessary).

•

During TL synchronous intervals, successful inspiratory efforts cause the ventilator to cycle from PEEPL to PEEPH. If there is no spontaneous (patient) effort, this transition takes place at the end of TL.

•

During TH synchronous intervals, successful expiratory efforts cause the ventilator to cycle from PEEPH to PEEPL . If there is no spontaneous exhalation, the transition to PEEPL level takes place at the end of TH.

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BiLevel option/800 Series Ventilators The actual durations of TH and TL vary according to whether or not the patient makes any spontaneous inspiratory efforts. To improve ventilator-patient synchrony, BiLevel allows TH and TL to be extended to prevent transitions to PEEPL during inspiration and to PEEPH during early exhalation. If the patient breathes spontaneously at either PEEP level, the monitored respiratory rate increases. If the patient triggers only transitions from one PEEP level to the other, the monitored respiratory rate can increase or decrease. If the patient does not trigger any transitions between PEEP levels and does not breathe spontaneously, the monitored respiratory rate equals the set rate, and the cycle interval equals 60/f. The minimum length of the synchronous interval during TL is at least 150 ms, and the maximum length is whichever is less: 0.4(TL ) or < 4 s. The minimum length of the synchronous interval during TH is at least 150 ms, and the maximum length is whichever is less: 0.3(TH ) or < 3 s.

Mode changes Changing to BiLevel mode from other modes follows the general guidelines for mode changes in 800 Series Ventilators: •

Any transition between modes always allows enough time for exhalation to avoid breath stacking.

•

Special scheduled events (for example, an inspiratory pause maneuver) is cancelled and rescheduled in the new mode.

•

The ventilator avoids apnea detection during a mode transition.

BiLevel differs from other ventilatory modes in that the PEEPH interval can last up to 30 seconds. Changing a breath timing variable or changing from BiLevel to another mode follows these guidelines: •

The change is made as soon as possible without compromising inspiration or exhalation.

•

Breaths are not stacked during inspiration.

•

New breaths are not delivered during the restricted phase of exhalation (the restricted phase of exhalation is defined as the first 200 ms of exhalation or the period when expiratory flow is > 50% of peak expiratory flow, whichever is greater).

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