Gastric emptying following brain injury: Effects of choice of sedation and intracranial pressure
To compare the effects of opioid and nonopioid sedation on gastric emptying. Prospective, randomized trial. University teaching hospital ICU. 21 brain injured patients requiring sedation, mechanical ventilation and intracranial pressure (ICP) monitoring for >24h. Patients were randomized to receive infusions of either morphine plus midazolam (M), or propofol (P). Gastric emptying was assessed by the paracetamol absorption technique and by residual volumes following a 200 ml test feed. Pre-sedation Glasgow Coma Score, mean ICP and the presence of bowel sounds were noted. Plasma concentrations of paracetamol were measured over 3 h following a 1 g gastric dose. There were no differencese in median peak paracetamol concentration (M, 18.5 versus P, 20.8 mg/l), median time to peak concentration (M, 20 versus P, 25 min), median area under the concentration-time curve (AUC), or in the median residual volumes at 1 h (M, 14 versus P, 10.5 ml) and 2 h (M, 5 versus P, 3 ml). In patients with ICP>20 mmHg, paracetamol concentrations were lower (p<0.05), and AUC after 30 min was lower (165 mg·min/l versus 411 mg·min/l,p=0.023). Mean ICP was correlated with AUC (Kendall rankp=0.027). Gastric emptying did not correlate with initial Glasgow Coma Score or presence of bowel sounds. Gastric emptying is not improved in patients with brain injury by avoiding morphine (1–8 mg/h) in the sedative regimen. Intracranial hypertension is associated with reduced gastric emptying.