Abstract
IntroductionExperimental work provides insight into potential lung protective strategies. The objective of this study was to evaluate markers of ventilator-induced lung injury after two different ventilation approaches: (1) a “conventional” lung-protective strategy (volume control (VC) with low tidal volume, positive end-expiratory pressure (PEEP) and paralysis), (2) a physiological approach with spontaneous breathing, permitting synchrony, variability and a liberated airway. For this, we used non-invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA), with the hypothesis that liberation of upper airways and the ventilator’s integration with lung protective reflexes would be equally lung protective.MethodsIn this controlled and randomized in vivo laboratory study, 25 adult White New Zealand rabbits were studied, including five non-ventilated control animals. The twenty animals with aspiration-induced lung injury were randomized to ventilation with either VC (6 mL/kg, PEEP 5 cm H2O, and paralysis) or NIV-NAVA for six hours (PEEP = zero because of leaks). Markers of lung function, lung injury, vital signs and ventilator parameters were assessed.ResultsAt the end of six hours of ventilation (n = 20), there were no significant differences between VC and NIV-NAVA for vital signs, PaO2/FiO2 ratio, lung wet-to-dry ratio and broncho-alveolar Interleukin 8 (Il-8). Plasma IL-8 was higher in VC (P <0.05). Lung injury score was lower for NIV-NAVA (P = 0.03). Dynamic lung compliance recovered after six hours in NIV-NAVA but not in VC (P <0.05). During VC, peak pressures increased from 9.2 ± 2.4 cm H2O (hour 1) to 12.3 ± 12.3 cm H2O (hour 6) (P <0.05). During NIV-NAVA, the tracheal end-expiratory pressure was similar to the end-expiratory pressure during VC. Two animals regurgitated during NIV-NAVA, without clinical consequences, and survived the protocol.ConclusionsIn experimental acute lung injury, NIV-NAVA is as lung-protective as VC 6 ml/kg with PEEP.Electronic supplementary materialThe online version of this article (doi:10.1186/cc13706) contains supplementary material, which is available to authorized users.
Highlights
Experimental work provides insight into potential lung protective strategies
Recent experimental studies suggest that spontaneous breathing [6], variability of breathing pattern [7], and proportionality [3,8] can aid in the attenuation of Ventilator-induced lung injury (VILI) in intubated animals with mild early experimental lung injury (partial arterial pressure of oxygen (PaO2) to inspired oxygen fraction (FIO2) ratio (P/F) approximately 100 to 150)
hydrochloric acid (HCl)-induced lung injury After acute lung injury (ALI), the mean P/F ratio was reduced from 300 ± 70 mmHg to 113 ± 48 mmHg for the noninvasive ventilation (NIV)-neurally adjusted ventilatory assist (NAVA) arm (P
Summary
Experimental work provides insight into potential lung protective strategies. The objective of this study was to evaluate markers of ventilator-induced lung injury after two different ventilation approaches: (1) a “conventional” lung-protective strategy (volume control (VC) with low tidal volume, positive end-expiratory pressure (PEEP) and paralysis), (2) a physiological approach with spontaneous breathing, permitting synchrony, variability and a liberated airway. The work of Brander et al in intubated rabbits with hydrochloric acid (HCl)-lung injury demonstrated that neurally adjusted ventilatory assist (NAVA) is at least as protective against VILI as the conventional protective ventilation strategy of volume control (VC) [3]. No studies have examined the use of noninvasive ventilation (NIV) in reducing VILI Such an approach could provide even greater lung protection by allowing the naturally occurring regulation of end-expiratory lung volume [9] and prevention of atelectasis, as well as avoiding the complications associated with having an endotracheal tube in place (for example, ineffective cough, colonization of the tube, and tracheal and glottal injury)
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