Overview

Promote More Natural Breathing

A full 71% of ventilated patients in the ICU show signs of agitation at least once during their stay,([FOOTNOTE=Siegel MD. Management of agitation in the intensive care unit. Clin Chest Med. 2003;24(4):713-725.],[ANCHOR=],[LINK=]) often leading to the need for sedation. One cause of agitation in ventilated patients may be patient-ventilator asynchrony.

Puritan Bennett™ PAV™*+ software can help clinicians address patient-ventilator asynchrony. It considers how a patient is breathing and enables the patient to determine the rate, depth and timing of each breath.

By improving the patient-ventilator relationship, clinicians can potentially make their patients more comfortable and help them breathe more naturally.

Pmus Calculator

Use the Delta Paw values to see the percentage of support needed to provide the physiologically appropriate levels of muscle effort.

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How It Works

We believe mechanical ventilation can and should be more natural. Our PAV™*+ software is a breath type that better manages work of breathing in spontaneously breathing patients and promotes natural breathing compared to conventional mechanical ventilation.††,([FOOTNOTE=Pohlman MC, et al. Excessive tidal volume from breath stacking during lung-protective ventilation for acute lung injury. Crit Care Med. 2008;36(11):3019-3023.],[ANCHOR=],[LINK=])  PAV™*+ software manages the patient’s work of breathing differently than other traditional modes of mechanical ventilation†† in the following ways.([FOOTNOTE=Puritan Bennett™ 980 Ventilator Operator's Manual],[ANCHOR=],[LINK=])

With PAV™*+ Breath Type, the Patient Defines Rate, Depth, and Timing

  • Flow is an indicator of demand. It tells us when the patient wants to begin inspiration, how deep the breath should be, when to end the breath and how often to breathe.([FOOTNOTE=Wilkins RL, Stoller JK, Scanlan CL. Egan’s Fundamentals of Respiratory Care. 8th ed. Louis, MO: Mosby; 2003.],[ANCHOR=],[LINK=])
  • The PAV™*+ software continuously monitors patient demand by measuring flow and volume every 5 milliseconds and by knowing the % Support set.
  • As patient demand changes, PAV™*+ software can change support pressure within the same breath.
When the % Support is set, the patient and the ventilator are sharing the work of breathing as defined by the clinician.
  • Work of breathing can be calculated using the equation of motion.([FOOTNOTE=Younes M, et al. Proportional Assist Ventilation. In: Tobin MJ. Principles And Practice of Mechanical Ventilation, Third Edition. McGraw Hill Professional; 2012.315-346.],[ANCHOR=],[LINK=])
  • When R and C are known, it’s possible to calculate patient-generated pressure (PMUS) and work of breathing in real time using the equation of motion.([FOOTNOTE=Younes M, et al. Proportional Assist Ventilation. In: Tobin MJ. Principles And Practice of Mechanical Ventilation, Third Edition. McGraw Hill Professional; 2012.315-346.],[ANCHOR=],[LINK=]),([FOOTNOTE=Bosma K, Ferreyra G, Ambrogio C, et al. Patient-ventilator interaction and sleep in mechanically ventilated patients: pressure support versus proportional assist ventilation. Crit Care Med. 2007;35(4):1048-1054.],[ANCHOR=],[LINK=]),([FOOTNOTE=Younes M, Webster K, Kun J, Roberts D, Masiowski B. A method for measuring passive elastance during proportional assist ventilation. Am J Respir Crit Care Med. 2001;164(1):50-60.],[ANCHOR=],[LINK=]),([FOOTNOTE=Grasso S, Ranieri WM, Brochard L, et al. Closed loop proportional assist ventilation (PAV): Results of a phase II multicenter trial. Am J Respir Crit Care Med. 2001, 163:A303.],[ANCHOR=],[LINK=]),([FOOTNOTE=Younes M, Riddle W, Polacheck J. A model for the relationship between respiratory neural and mechanical outputs: III. Validation. J Appl Physiol. 1981;51(4):990-1001.],[ANCHOR=],[LINK=])

PMUS + PVENT = (flow x resistance) + (volume ÷ compliance)

  • PAV™*+ software measures resistance and compliance every 4-10 breaths.
  • Once % Support is set, clinicians can use the work of breathing (WOB) bar for real-time feedback on how much work the patient is doing.
  • The work of breathing bar displays both total work of breathing (WOBTOT) and the patient work of breathing (WOBPT).
  • Adjust the % Support setting to maintain the patient’s WOB (WOBPT) within the green zone.
  • Associated fatigue values for work of breathing are shown as being outside the green zone.

The work of breathing bar, when coupled with good clinical assessment, can help take the guesswork out of determining the appropriate level of mechanical ventilation support. Providing real-time feedback on work of breathing helps the clinician keep the patient at a sustainable level of work—reducing the risk for respiratory muscle atrophy, but off-loading enough work to avoid fatigue.([FOOTNOTE=Hermans G. Increased duration of mechanical ventilation is associated with decreased diaphragmatic force: a prospective observational study. Crit Care. 2010;14:R127.],[ANCHOR=],[LINK=]),([FOOTNOTE=Anzueto A, Peters JI, Tobin MJ, et al. Effects of prolonged controlled mechanical ventilation on diaphragmatic function in healthy adult baboons. Crit Care Med. 1997;25(7):1187-1190.],[ANCHOR=],[LINK=]),([FOOTNOTE=Haitsma JJ. Diaphragmatic dysfunction in mechanical ventilation. Curr Opin Anaesthesiol. 2011;24(2):214-218.],[ANCHOR=],[LINK=])

Learn more about how PAV™*+ software works.

Understanding Patient-Ventilator Asynchrony

People display normal variability in their breathing patterns even at rest. In contrast, although a necessary medical intervention, mechanical ventilation uses some sort of fixed parameter in almost all currently available modes. If the mechanical breath is delivered in a fashion that the patient doesn’t want or expect (too short, not enough flow, too long, etc.), asynchrony between the ventilator and the patient, discomfort, anxiety and fatigue can result.([FOOTNOTE=de Wit M. Monitoring of patient ventilator interaction at the bedside. Respiratory Care. 2011;56(1):61-68.],[ANCHOR=],[LINK=])

Eight out of 10 ventilated patients come off the vent within three to four days with little difficulty.([FOOTNOTE=Thille AW et al. Patient-ventilator asynchrony during assisted mechanical ventilation. Intensive Care Med. 2006;32(10):1515-1522.],[ANCHOR=],[LINK=]),([FOOTNOTE=Anzueto A, Peters JI, Tobin MJ, et al. Effects of prolonged controlled mechanical ventilation on diaphragmatic function in healthy adult baboons. Crit Care Med. 1997;25(7):1187-1190.],[ANCHOR=],[LINK=]) They might be uncomfortable under mechanical ventilation, but they are able to wean from the ventilator. Still, in these patients, improving patient-ventilator synchrony may potentially result in less anxiety and need for sedation.([FOOTNOTE=Siegel MD. Management of agitation in the intensive care unit. Clin Chest Med. 2003;24(4):713-725.],[ANCHOR=],[LINK=])

Those who stay on ventilation longer (~25%) and continue to fail to wean use 50% of our ICU resources, accounting for 40% of all ICU costs.3,([FOOTNOTE=Hermans G. Increased duration of mechanical ventilation is associated with decreased diaphragmatic force: a prospective observational study. Crit Care. 2010;14:R127.],[ANCHOR=],[LINK=]) In these patients, asynchrony may have a greater impact.2,([FOOTNOTE=de Wit M, Miller KB, Green DA, Ostman HE, Gennings C, Epstein SK. Ineffective triggering predicts increased duration of mechanical ventilation. Crit Care Med. 2009;37(10):2740-2745.],[ANCHOR=],[LINK=]),([FOOTNOTE=Xirouchaki N, Kondili E, Vapoidi K, et al. Proportional assist ventilation with load-adjustable gain factors in critically ill patients: comparison with pressure support. Int Care Med. 2008;34:2026-2034.],[ANCHOR=],[LINK=]),([FOOTNOTE=Epstein SK. Optimizing patient-ventilator synchrony. Semin Respir Crit Care Med. 2001;22(2):137-152.],[ANCHOR=],[LINK=])

  • *Proportional Assist and PAV are registered trademarks of The University of Manitoba, Canada. Used under license.

  • † Compared to conventional mechanical ventilation (VC,VC+,PC,PS)

  • †† VC, VC+, PC, PS and PSV based modes