Patient-Ventilator Interaction During Acute Lung Injury, and the Role of Spontaneous Breathing: Part 2: Airway Pressure Release Ventilation

Airway pressure release ventilation (APRV) was originally described as a mode to treat lunginjured patients with the goal to maintain a level of airway pressure that would not depress the cardiac function, deliver mechanical breaths without excessive airway pressure, and to allow unrestricted spontaneous ventilation. Indeed, based on its design, APRV has technological features that serve the goals of safety and comfort. Animal studies suggest that APRV leads to alveolar stability and recruitment which result in less lung injury. These features are sought in patients at risk for lung injury or with ARDS. APRV allows unrestricted spontaneous ventilation, which is welcome in the era of less sedation and increased patient mobility (the effects in terms of lung injury remain to be explored). However, we must highlight that the performance of APRV is dependent on the operator-selected settings and the ventilator's performance. The clinician must select the appropriate settings in order to make effective the imputed benefits. This is a challenge when the ventilator's performance is not uniform, and the outcomes depend on high precision settings (very short expiratory time), where small variations can lead to undesired outcomes (de-recruitment or large tidal volumes leading to lung injury). Finally, we do not have evidence that APRV (as originally described) improves relevant clinical outcomes of patients with ARDS. For APRV to become the primary mode of ventilation for ARDS, it will require development of sound protocols and technological enhancements to ensure its performance and safety. For now, APRV does have a greater potential for adversely affecting patient outcome than improving it; unless definitive data are forthcoming demonstrating outcome benefits from the use of APRV in ARDS, there is no reason to consider this approach to ventilatory support. Key words: Airway pressure release ventilation, biphasic positive-pressure breathing, lung injury, work of breathing, auto PEEP [Respir Care 2016;61(6):761-773.

Section: Preservation Of Spontaneous Breathing To Improve Gas Exchangmentioning

confidence: 99%

Section: Aprv and Comfortmentioning

confidence: 99%

Should Airway Pressure Release Ventilation Be the Primary Mode in ARDS?

Mireles-Cabodevila

Kacmarek

2016

“…However, the literature contains numerous, largely unsubstantiated claims that certain pressure modes are superior to volume controlled modes for patients with ARDS. 10 In general, benefit has been inferred from improvements in arterial oxygenation and better patient/ventilator synchrony. For the most part, these improvements can be traced to an increase in V T and may therefore not be inherent to ventilation mode per se.…”

Section: T and Lung Injurymentioning

confidence: 99%

The Hidden Consequences of Ventilator Management Decisions

Hubmayr

Oeckler

2014

In the following perspective, we will highlight seemingly remote, downstream consequences of common ventilator management decisions. For example, a change in PEEP may alter venous return, blood pressure, cardiac output, arterial and venous blood gas tensions, metabolic rate, respiratory sensations, breathing pattern, and the work of breathing. If providers consider any of these changes dangerous or maladaptive, they may initiate additional interventions in the form of vasoactive agents, intravenous fluids, and/or sedatives, all of which have their own risk/benefit profile. The approach to such co-interventions is rarely addressed even in well-designed large clinical trials. Therefore, it is often impossible to infer intervention-specific mechanisms of action and/or identify the phenotype of responders and nonresponders in such trials. On the flip side, in preclinical research intended to uncover mechanisms, experimental animals are rarely treated the way a critically ill patient would be. For respiratory therapists, this knowledge gap stresses the imperative to think beyond the lungs and to communicate ventilator management decisions with all members of the healthcare team.

“…13 This mode maximizes mean airway pressure while simultaneously encouraging the purported physiologic advantages of spontaneous ventilation. It may be thought of as supporting the patient on 2 different levels of continuous positive airway pressure (CPAP).…”

Section: Airway Pressure Release Ventilationmentioning

confidence: 99%

“…This paper summarizes what I took to be the most important messages of the individual presentations and the discussions that followed them, and offers some of my own observations on this central component of the management of patients with acute respiratory failure. With a few exceptions I will not attempt to cite the most important primary work that has been done in this field; the individual papers in these 2 special issues [1][2][3][4][5][6][7][8][9][10][11][12][13][14] provide a comprehensive and authoritative review of the literature pertaining to PVI.…”

Section: Introductionmentioning

confidence: 99%

Patient-Ventilator Interaction

Pierson

2011

SummaryPatient-ventilator interaction has been the focus of increasing attention from both manufacturers and researchers during the last 25 years. There is now compelling evidence that passive (controlled) mechanical ventilation leads to respiratory muscle dysfunction and atrophy, prolonging the need for ventilatory support and predisposing to a number of adverse patient outcomes. Although there is consensus that the respiratory muscles should retain some activity during acute respiratory failure, patient-ventilator asynchrony is now recognized as a cause of ineffective ventilation, impaired gas exchange, lung overdistention, increased work of breathing, and patient discomfort. Far more common than previously recognized, it also predisposes to respiratory muscle dysfunction and other complications, leads to excessive use of sedation, increases the duration of ventilatory support, and interferes with weaning. Appropriate recognition and management of patient-ventilator asynchrony require bedside assessment of ventilator graphics as well as direct patient observation. Among currently available ventilation modes and approaches, none has been shown to be clearly superior to all the others with respect to patient-ventilator interaction, and strongly held prefer- 214RESPIRATORY CARE • FEBRUARY 2011 VOL 56 NO 2 ences among investigators have led to controversy and difficulties in carrying out appropriate studies evaluating them. As a result, marked practice variation exists among different specialties as well as in different institutions and geographical areas. The respected authorities on mechanical ventilation who participated in this conference differed in the modes they preferred but agreed that proper understanding and use according to the individual patient's needs are more important than which mode is chosen. Conference participants discussed the determinants, manifestations, and epidemiology of patient-ventilator asynchrony, and described and compared several ventilation modes aimed specifically at preventing and ameliorating it. The papers arising from these discussions represent the most thorough examination of this important aspect of respiratory care yet published.