Protective effects of low respiratory frequency in experimental ventilator-associated lung injury*

Conrad, Steven A.; Zhang, Shu; Arnold, Thomas C.; Scott, L.; Carden, Donna L.

doi:10.1097/01.ccm.0000159532.56865.8a

Cited by 46 publications

(30 citation statements)

References 31 publications

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“…However and most importantly, they also concluded that the injury was prevented with a concomitant decrease in V T . 29,30 In support of this, Conrad et al 30 found that, at a normal V T (5 mL/kg) versus a high (20 mL/kg) V T , the cyclic stretch did not induce injury across a range of breathing frequencies.…”

Section: Discussionmentioning

confidence: 69%

“…A concern regarding ventilation at higher frequencies is the potential increase in lung injury due to repeated exposure to injurious ventilatory cycles. This has been examined in several studies [29][30][31] most recently by Vaporidi et al 32 They demonstrated a correlation with lung injury in a mouse model. However and most importantly, they also concluded that the injury was prevented with a concomitant decrease in V T .…”

Section: Discussionmentioning

confidence: 99%

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Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

et al. 2014

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BACKGROUND: Mid-frequency ventilation (MFV) is a mode of pressure control ventilation based on an optimal targeting scheme that maximizes alveolar ventilation and minimizes tidal volume (V T ). This study was designed to compare the effects of conventional mechanical ventilation using a lung-protective strategy with MFV in a porcine model of lung injury. Our hypothesis was that MFV can maximize ventilation at higher frequencies without adverse consequences. We compared ventilation and hemodynamic outcomes between conventional ventilation and MFV. METHODS: This was a prospective study of 6 live Yorkshire pigs (10 ؎ 0.5 kg). The animals were subjected to lung injury induced by saline lavage and injurious conventional mechanical ventilation. Baseline conventional pressure control continuous mandatory ventilation was applied with V T ‫؍‬ 6 mL/kg and PEEP determined using a decremental PEEP trial. A manual decision support algorithm was used to implement MFV using the same conventional ventilator. We measured P aCO 2 , P aO 2 , end-tidal carbon dioxide, cardiac output, arterial and venous blood oxygen saturation, pulmonary and systemic vascular pressures, and lactic acid. RESULTS: The MFV algorithm produced the same minute ventilation as conventional ventilation but with lower V T (؊1 ؎ 0.7 mL/kg) and higher frequency (32.1 ؎ 6.8 vs 55.7 ؎ 15.8 breaths/min, P < .002). There were no differences between conventional ventilation and MFV for mean airway pressures (16.1 ؎ 1.3 vs 16.4 ؎ 2 cm H 2 O, P ‫؍‬ .75) even when auto-PEEP was higher (0.6 ؎ 0.9 vs 2.4 ؎ 1.1 cm H 2 O, P ‫؍‬ .02). There were no significant differences in any hemodynamic measurements, although heart rate was higher during MFV. CONCLUSIONS: In this pilot study, we demonstrate that MFV allows the use of higher breathing frequencies and lower V T than conventional ventilation to maximize alveolar ventilation. We describe the ventilatory or hemodynamic effects of MFV. We also demonstrate that the application of a decision support algorithm to manage MFV is feasible.

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Section: Discussionmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

et al. 2014

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“…Dynamic forces generated by MV could also affect the mucosal epithelium and respiratory secretions. However, while there are a considerable number of studies that have investigated the influence of different patterns of MV on pulmonary parenchyma [1,9,10], the influence of MV on mucociliary function has received little attention. Impaired mucociliary clearance [11] and mucus concentration [12] seem to be important factors that can influence the formation of bacterial colonies, which represent a potential threat for patients undergoing MV.…”

Section: Introductionmentioning

confidence: 99%

Effects of different mechanical ventilation strategies on the mucociliary system

et al. 2010

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“…This claim has not been directly studied in APRV, but it has been studied in animals receiving conventional ventilation. [27][28][29][30] Conrad et al 28 demonstrated a clear relationship between capillary permeability (a marker of VILI) and breathing frequency; however, this was only with large V T (20 mL/kg). They found no effect of frequency in the animals ventilated with V T of 5 mL/kg.…”

Section: Higher Mean Airway Pressures For a Given Minutementioning

confidence: 99%

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

Mireles-Cabodevila

Kacmarek

2016

Respir Care

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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.

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Protective effects of low respiratory frequency in experimental ventilator-associated lung injury*

Abstract: Reduction in respiratory frequency to values much lower than normal ameliorated experimental ventilator-induced hyperinflation lung injury as determined by pulmonary capillary filtration coefficient.

Cited by 46 publications

References 31 publications

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

Application of Mid-Frequency Ventilation in an Animal Model of Lung Injury: A Pilot Study

Effects of different mechanical ventilation strategies on the mucociliary system

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

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