A model of gastric emptying using paracetamol absorption in intensive care patients.

OBJECTIVES: To describe the range and factors which may affect gastric emptying in the ICU patient.
DESIGN: Validation sample.
SETTING: The adult Intensive Care Unit (ICU) of a teaching hospital. PATIENTS: Twenty-seven ICU patients, aged 18-65 years were studied within 3 days of their ICU admission. All patients had normal hepatic and renal chemistry and had no contraindications to enteral feeding.
MEASUREMENTS AND MAIN RESULTS: The area under the concentration curve from 0-60 min (AUC60) of a paracetamol absorption test was used as the measure of gastric emptying. The variables of the presence or absence of bowel sounds, volume of gastric aspirate ( > 50 ml or < 50 ml), an estimated risk of death (ROD), an APACHE II score calculated 24 h before the study, a pHi measurement, the use of dopamine (2.5-5 microg/kg, yes or no) and of opioids were included in a multiple regression analysis. Using Pearson correlation, AUC60 was positively correlated with the estimated ROD (r = 0.50, p < 0.05). There was a statistically significant difference in the mean AUC60 between those patients who did, and those who did not, receive dopamine (t = 3.06, p < 0.005). On multiple regression analysis the only variable which was significantly associated with AUC60 was estimated ROD, which accounted for 25% of the variance in AUC60.
CONCLUSION: The results suggest that there is a wide range in gastric emptying in critically ill patients. The results may be due to the case mix of the patients. The use of dopamine may adversely affect gastric emptying and requires further investigation in the ICU patient. Prediction of gastric emptying is difficult in these patients and further investigation is necessary in order to improve our understanding of this process.