The association between non-depolarizing neuromuscular blockade agents and survival to discharge in dogs undergoing mechanical ventilation: a multi-center retrospective study of 227 dogs (2010–2020)

Objective: To evaluate the association between neuromuscular blockade agent (NMBA) use and outcome in dogs undergoing mechanical ventilation (MV), including survival to discharge, and complications. Methods: The medical records for 227 mechanically ventilated dogs were reviewed for NMBA use, parameters of respiratory status (PaO₂, PCO₂, PF ratio, SpO₂), MV settings, MV complications, and survival outcome. Results: The NMBA and non-NMBA groups included 28 and 199 dogs, respectively. The median partial pressures of oxygen in arterial blood (PaO₂) in the NMBA and non-NMBA groups were 63 and 57 mmHg, respectively (P = 0.24). The median partial pressures of blood carbon dioxide levels were 58 and 51 mmHg, respectively (P = 0.07). The pulse oximetry percentage (SpO₂) prior to initiation of MV were 88 and 94%, respectively (P = 0.02). The median PF ratios prior to MV were 90 and 215, respectively (P = 0.02). The median durations of MV were 18 and 24 h, respectively (P = 0.32). Eight (28.6%) dogs that received NMBAs survived to discharge, while 51 dogs (32.3%) that did not receive NMBAs survived to discharge (P = 0.87). Both PF ratio and SpO₂ values were significantly lower in dogs that received NMBAs compared to dogs that did not (P = 0.02 and P = 0.02, respectively). There was no significant difference in tidal volume or peak inspiratory pressure at the time of MV initiation (P = 0.17 and P = 0.09, respectively). There was no significant difference between the incidence of complications in dogs that received NMBAs and those that did not (P = 0.08). Conclusion: This study revealed no statistical significance between NMBA use and survival or complications. However, dogs in the NMBA group likely had more severe hypoxemia than the non-NMBA group, as indicated by their lower PF ratios and SPO₂ values prior to initiation of mechanical ventilation. The similarities in survival rate between the NMBA and non-NMBA patient populations, despite higher severity of respiratory pathology in the NMBA group, may suggest a potential therapeutic benefit to NMBA use for MV patients. Further investigation into the use of NMBAs in patients undergoing MV are warranted.