Performance Characteristics of 10 Home Mechanical Ventilators in Pressure-Support Mode

doi:10.1378/chest.127.5.1784

Chest

Volume 127, Issue 5, May 2005, Pages 1784-1792

https://doi.org/10.1378/chest.127.5.1784 Get rights and content

Objective

Inspiratory pressure (Pi) support delivered by a bilevel device has become the technique of choice for noninvasive home ventilation. Considerable progress has been made in the performance and functionality of these devices. The present bench study was designed to compare the various characteristics of 10 recently developed bilevel Pi devices under different conditions of respiratory mechanics.

Design

Bench model study.

Setting

Research laboratory, university hospital.

Measurements

Ventilators were connected to a lung model, the mechanics of which were set to normal, restrictive, and obstructive, that was driven by an ICU ventilator to mimic patient effort. Pressure support levels of 10 and 15 cm H₂O, and maximum were tested, with “patient” inspiratory efforts of 5, 10, 15, 20, and 25 cm H₂O. Tests were conducted in the absence and presence of leaks in the system. Trigger delay, trigger-associated inspiratory workload, pressurization capabilities, and cycling were analyzed.

Results

All devices had very short trigger delays and triggering workload. Pressurization capability varied widely among the machines, with some bilevel devices lagging behind when faced with a high inspiratory demand. Cycling was usually not synchronous with patient inspiratory time when the default settings were used, but was considerably improved by modifying cycling settings, when that option was available.

Conclusions

A better knowledge of the technical performance of bilevel devices (ie, pressurization capabilities and cycling profile) may prove to be useful in choosing the machine that is best suited for a patient's respiratory mechanics and inspiratory demand. Clinical algorithms to help set cycling criteria for improving patient-ventilator synchrony and patient comfort should now be developed.

Section snippets

Ventilators Tested

The following 10 newest generation bilevel devices were tested: Synchrony (Respironics; Murrysville, PA); Somnovent (Weinmann; Hamburg, Germany); VPAP II ST and VPAP III ST-A (ResMed; North Ryde, Australia); Moritz ST (MAP; Martinsried, Germany); Knightstar 330 (Tyco-Nellcor Puritan Bennett; Pleasanton, CA); PV 102+ (Breas; Mölnycke, Sweden); VS Integra and VS Ultra (Saime; Savigny le Temple, France); and SmartAir+ (Airox; Pau, France). The main characteristics of the machines are summarized in

Inspiratory Trigger

The Td was < 200 ms for all machines. Four devices had a mean Td of < 100 ms (Fig 2).

For a minimal inspiratory effort, PTPt was very small at each level of pressure support tested (10 and 15 cm H₂O, and the PSmax), and was slightly but significantly higher on one device (Fig 3). The negative pressure deflections preceding the response by the device averaged between 0.7 and 1.2 cm H₂O for all levels of pressure support. With high levels of inspiratory effort, a mean pressure of 4 ± 1 cm H₂O was

Discussion

The results of our tests highlight the following characteristics of the 10 bilevel ventilation devices:

1
Td was < 200 ms on all machines, with four of the machines having delays of < 100 ms.
2
Even though differences existed among machines, all devices required very little triggering effort (ie, low PTPt).
3
Major differences were found between the bilevel ventilation devices in terms of pressurization performance (PTP₃₀₀ and PTP₅₀₀), ranging from 0 to 80% of ideal pressurization, especially when

Conclusion

In a bench model study, 10 recently developed bilevel devices that were designed for home ventilation use exhibited very good triggering characteristics, in terms of both Td and required inspiratory effort. Their pressurization characteristics varied widely, suggesting that some of the devices might be limited in patients with high inspiratory demand (eg, in the setting of acute respiratory failure), or for those stable patients with marked obesity or severely restrictive respiratory mechanics.

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Citation Excerpt :
We used four indicators to characterize inspiratory trigger. The indicators were as follows: triggering delay (ms), which measured the time lag between the beginning of simulated effort and the onset of pressure support; flow to trigger (L/min), defined as the value of patient flow measured at the onset of support pressure; pressure to trigger (cm H2O), defined as the value of muscular pressure (Pmus) measured at the onset of support pressure; and inspiratory pressure-time product (PTPt) (cm H2O × s), defined as the area under the pressure-time curve between the onset of inspiratory effort and the return to the set positive end-expiratory pressure as described.14 We used three indicators to characterize pressurization.
SARS-CoV-2 aerosolization during noninvasive positive-pressure ventilation may endanger health care professionals. Various circuit setups have been described to reduce virus aerosolization. However, these setups may alter ventilator performance.
What are the consequences of the various suggested circuit setups on ventilator efficacy during CPAP and noninvasive ventilation (NIV)?
Eight circuit setups were evaluated on a bench test model that consisted of a three-dimensional printed head and an artificial lung. Setups included a dual-limb circuit with an oronasal mask, a dual-limb circuit with a helmet interface, a single-limb circuit with a passive exhalation valve, three single-limb circuits with custom-made additional leaks, and two single-limb circuits with active exhalation valves. All setups were evaluated during NIV and CPAP. The following variables were recorded: the inspiratory flow preceding triggering of the ventilator, the inspiratory effort required to trigger the ventilator, the triggering delay, the maximal inspiratory pressure delivered by the ventilator, the tidal volume generated to the artificial lung, the total work of breathing, and the pressure-time product needed to trigger the ventilator.
With NIV, the type of circuit setup had a significant impact on inspiratory flow preceding triggering of the ventilator (P < .0001), the inspiratory effort required to trigger the ventilator (P < .0001), the triggering delay (P < .0001), the maximal inspiratory pressure (P < .0001), the tidal volume (P = .0008), the work of breathing (P < .0001), and the pressure-time product needed to trigger the ventilator (P < .0001). Similar differences and consequences were seen with CPAP as well as with the addition of bacterial filters. Best performance was achieved with a dual-limb circuit with an oronasal mask. Worst performance was achieved with a dual-limb circuit with a helmet interface.
Ventilator performance is significantly impacted by the circuit setup. A dual-limb circuit with oronasal mask should be used preferentially.
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Financial support for this study was provided by the firms ResMed and Weinmann.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestjournal.org/misc/reprints.shtml).

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Chest

Laboratory and Animal InvestigationsPerformance Characteristics of 10 Home Mechanical Ventilators in Pressure-Support Mode

Objective

Design

Setting

Measurements

Results

Conclusions

Section snippets

Ventilators Tested

Inspiratory Trigger

Discussion

Conclusion

Chest

Chest

Chest

Chest

Respir Physiol

Lancet

Noninvasive ventilation and obstructive lung diseases

Eur Respir J

Comparison of two different modes for noninvasive mechanical ventilation in chronic respiratory failure: volume versus pressure controlled device

Eur Respir J

Laboratory and Animal Investigations
Performance Characteristics of 10 Home Mechanical Ventilators in Pressure-Support Mode