Impaired gastric emptying in mechanically ventilated, critically ill patients

ObjectiveTo measure gastric emptying in critically ill patients using an acetaminophen absorption model and determine which variables are associated with impaired gastric emptying.DesignA prospective, cohort study.SettingA medical/surgical ICU at a tertiary care hospital: Hamilton General Hospital, Hamilton, Ontario.Patients and participantsWe recruited 72 mechanically ventilated patients expected to remain in the ICU for more than 48h. Our results were compared to those in healthy volunteers.InterventionWithin 48 h of admission to the ICU, 1.6 g acetaminophen suspension were administered via a nasogastric tube into the stomach. Blood samples were drawn at=0, 30, 60, 90, and 120 min for measurement of plasma acetaminophen levels determined by the enzymatic degradation method.Measurements and resultsMaximal concentration of acetaminophen was 94.1 (75.3) μmol/l compared to 208.4 (33.1) μmol/l in a control population (p<0.0001). The time to reach the maximal concentration was 105 min (60–180) compared to 30 min (15–90) in controls (p<0.0001). The area under the time-acetaminophen concentration curvet=120 was 9301 (7343) μmol/min per 1 compared to 11644 (1336) μmol/min per 1 in the controls (p=0.28). The variables associated with delayed gastric emptying were age, sex and use of opioids for analgesia and sedation.ConclusionsGastric emptying is delayed in critically ill patients. The important consequences of this phenomenon include intolerance to enteral nutrition and gastric colonization. Strategies to minimize the use of narcotics may improve gastric emptying. Studies to examine the effect of gastrointestinal prokinetic agents on gastric emptying are needed.