The depth of neuromuscular blockade is not related to chest wall elastance and respiratory mechanics in moderate to severe acute respiratory distress syndrome patients. A prospective cohort study

Background: Data concerning the depth of neuromuscular blockade (NMB) required for effective relaxation of the respiratory muscles in ARDS are scarce. We hypothesised that complete versus partial NMB can modify respiratory mechanics.Method: Prospective study to compare the respiratory mechanics of ARDS patients according to the NMB depth. Each patient was analysed at two times: deep NMB (facial train of four count (TOFC) = 0) and intermediate NMB (TOFC >0). The primary endpoint was the comparison of chest wall elastance (ELCW) according to the NMB level.Results: 33 ARDS patients were analysed. There was no statistical difference between the ELCW at TOFC = 0 compared to TOFC >0: 7 cmH(2)O/l [5.7-9.5] versus 7 cmH(2)O/l [5.3-10.8] (p = 0.36). The depth of NMB did not modify the expiratory nor inspiratory oesophageal pressure (Pes(exp) = 8 cmH(2)O [5-9.5] at TOFC = 0 versus 7 cmH(2)O [5-10] at TOFC >0; (p = 0.16) and Pes(insp) = 10 cmH(2)O [8.2-13] at TOFC = 0 versus 10 cmH(2)O [8-13] at TOFC >0; (p = 0.12)).Conclusion: In ARDS, the relaxation of the respiratory muscles seems to be independent of the NMB level.