Effect of respiratory acid-base balance on rocuronium-induced neuromuscular blockade and sugammadex-induced reversal in rat phrenic nerve hemidiaphragm.

Background: This study utilized an ex-vivo model to examine the effect of respiratory acid-base balance on rocuronium-induced neuromuscular blockade and sugammadex-induced recovery and to assess the relationship between train-of-four (TOF) ratio and the first twitch tension of TOF (T1). Methods: After obtaining approval from the Asan Ethics Committee of the Laboratory of Animal Research, phrenic nerve-hemidiaphragm specimens were obtained from 30 adult Sprague-Dawley rats and randomly assigned to control (95% O2 + 5% CO2), respiratory alkalosis (97.5% O2 + 2.5% CO2), and acidosis (91% O2 + 9% CO2) groups, immersed in the Krebs' solution, and stimulated with TOF pattern at 20-s intervals. Rocuronium loading and booster doses were administered every 10 min until > 95% blockade T1 was achieved. Recovery was monitored using T1 and TOF ratios (TOFR) until T1 to > 95% and the TOFR to > 0.9. Results: Left shift of the dose-response curve of T1% and TOFR occurred only in the acidosis group vs the alkalosis group (P < 0.0001). The recovery progression of T1 and TOFR differed significantly between the groups (P = 0.0001). The total doses of rocuronium and sugammadex were different between the control and respiratory acidosis groups (P = 0.00318 and P = 0.00315, respectively), and between the respiratory acidosis and alkalosis groups (P = 0.0007 and P = 0.0007, respectively). Conclusions: Acid-base alterations due to CO2 changes may influence rocuronium-induced neuromuscular blockade and sugammadex-induced reversal. However, despite some inter-group differences, statistically discrete results were not obtained across the experimental groups.