Integration of COclearance and continuous neurally adjusted ventilatory assist in an animal model of respiratory distress.

Abstract

BACKGROUND: A mode of ventilation is introduced that integrates COclearance ("Through-Flow", TF) with Continuous Neurally Adjusted Ventiator Assist (cNAVA). The new mode, referred to as "TF+cNAVA", is a unidirectional flow system where inspiratory lumen(s) within an ET tube delivers fresh gas at the carina and the main ET tube lumen allows overflow of fresh gas to provide assist in proportion to the electrical activity of the diaphragm (Edi). The aim was to evaluate the effect of TF+cNAVA on breathing parameters during respiratory provocations, its reproducibility, and its sustainability. Conventional NAVA was the comparison. METHODS: 46 rabbits were studied in three protocols: (i) NAVA vs. TF+cNAVA in open chest with added dead space, acute lung injury (ALI), single lung ventilation, and vagotomy (n&#x202f;=&#x202f;8); (ii) Eight repeated comparisons, to demonstrate reproducibility (n&#x202f;=&#x202f;8); (iii) ALI rabbits (n&#x202f;=&#x202f;30) randomized to either NAVA or TF+cNAVA (6&#x202f;h). Parameters studied: Edi, tidal volume (V), breathing frequency (F), minute ventilation (V), transpulmonary pressure (P), and PaCO. RESULTS: With added provocations, NAVA showed an increase in Edi, V, F, Pand Vfrom baseline by 43&#x202f;% (P&#x202f;=&#x202f;0.004). TF+cNAVA significantly reduced Edi, V, F, P, and Vfrom baseline, by 73&#x202f;% (P&#x202f;<&#x202f;0.001). In NAVA vs. TF+cNAVA crossover, TF+cNAVA consistently reached apneic levels for Edi, V, F, P, and V. During 6&#x202f;h of TF+cNAVA, PaCO, Edi, V, F, P, and Vwere significantly reduced compared to NAVA and baseline. CONCLUSION: TF+cNAVA unloads respiratory muscles and suppresses respiratory drive, while reducing lung distending pressure.