Lung protection during non-invasive synchronized assist versus volume control in rabbits

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.

Comparison between neurally-assisted, controlled, and physiologically variable ventilation in healthy rabbits

“…These findings are in agreement with recent reports where variations in tidal volume were applied during volumecontrolled ventilation, 25 or when the lungs were ventilated with a synchronised and assisted modality, the NAVA. 26 Regular sighs in the PCS group were able to ensure alveolar recruitment. However, regular application of sighs, at a relatively moderate level (20 cm H 2 O) led to comparable degree of lung injury as observed with a conventional pressurecontrolled mode (Fig.…”

Non-invasive neurally adjusted ventilatory assist in preterm infants: a randomised phase II crossover trial

“…Neurally adjusted ventilatory assist (NAVA), which uses electrical activity of the diaphragm (Edi) to trigger, set the amount of pressure and cycle off the ventilator, has been shown to reduce asynchrony during NIV in a small number of low-birthweight infants6 and to maintain synchrony in rabbits despite high levels of leaks 7. However, data concerning NIV-NAVA in preterm infants are lacking, and physiological validation of patient–ventilator synchrony of NIV-NAVA is essential prior to clinical application in this population.…”

The effects of aspirated thickened water on survival and pulmonary injury in a rabbit model

“…The groups underwent 3 consecutive days of 1.5 mL/kg intratracheal instillation of water (n = 8), XG‐thickened water (Resource Thicken Up Clear; Nestlé, Florham Park, NJ) (n = 8), and CS‐thickened water (Resource ThickenUp; Nestlé) (n = 8). The dosage was selected based on previous studies conducting tracheal instillation in rabbits …”

“…The dosage was selected based on previous studies conducting tracheal instillation in rabbits. 14,15 Rabbits were anesthetized with ketamine (5 mg/kg; Pfizer, New York, NY) and xylazine (1 mg/kg; Bayer, Leverkusen, Germany) via an auricular intravenous (IV) catheter. A 3.5-mm uncuffed endotracheal tube (Sheridan; Teleflex Medical, Triangle Park, NC) was inserted, and animals were kept breathing spontaneously.…”