Effect of Neuromuscular Blocking Agents on Sedation Requirements in Trauma Patients with an Open Abdomen

Abstract

The appropriate level of sedation in patients with an open abdomen following damage control laparotomy (DCL) is debated. Chemical paralysis with neuromuscular blocking agents (NMBAs) has been used to decrease time to abdominal closure. We sought to evaluate the effect of NMBA use on sedation requirements in patients with an open abdomen and to determine the effect of sedation on patient outcomes. A retrospective cohort study was conducted at an American College of Surgeons' verified level 1 trauma center. Adult trauma patients who underwent DCL between 2009 and 2015 were included. Patients with an intensive care unit length of stay of less than 48 hours and those who died before abdominal closure were excluded. The NMBA+ group received continuous NMBA within 24 hours of DCL; the NMBA- group did not. The primary outcome was cumulative sedation dose during the 7 days following DCL. Secondary outcomes included Richmond Agitation-Sedation Scale (RASS) score, mechanical ventilation-free days, and delirium-coma-free days. Delirium-coma-free days were analyzed with linear regression. A total of 222 patients were included (NMBA+ 125; NMBA- 97). Demographics were similar between groups including age, Injury Severity Score, and mechanism of injury. The median time to closure in the overall cohort was 2 days (interquartile range [IQR] 1-2 days). Propofol and fentanyl were the primary sedatives used. The NMBA+ group received higher cumulative doses of propofol (NMBA+ 5405 mg, IQR 3103-10,573 mg; NMBA- 3601 mg, IQR 1605-6887 mg; p=0.007), but not of fentanyl. Time to abdominal closure, but not NMBA use, was associated with a higher cumulative propofol dose on multivariate analysis. The NMBA+ group had significantly lower RASS scores on the first 3 days following DCL. Mechanical ventilation-free days (NMBA+ 20 days vs NMBA- 18 days, p=0.960) and delirium-coma-free days (NMBA+ 18 days vs NMBA- 18 days, p=0.610) were similar between the groups. On linear regression, cumulative propofol dose was associated with fewer delirium-coma-free days (β-coefficient -0.007, 95% confidence interval -0.015 to -0.003). In trauma patients managed with DCL, higher cumulative sedative doses were administered in patients who received adjunctive NMBA, although NMBA therapy was not associated with a higher cumulative propofol dose on multivariate analysis. Consideration must be given to the potential effect of sedation on delirium and awakening following DCL.

Keywords: damage control laparotomy; delirium; neuromuscular blockade; open abdomen; sedation; trauma.