Objective

To evaluate the paracetamol absorption test in comparison with the clinical test of gastric residual volume, as indicators of gastric motility, in order to initiate peros feeding in critically ill patients.

Design

A prospective self-controlled study, evaluating a clinical and a laboratory test.

Setting

An adult medical–surgical university ICU.

Patients and methods

All patients were studied in three steps. Step I. The gastric residual volume was measured 1 hour (by aspiration of the gastric content) after the delivery of 200 ml D5W (gastric residual volume test [GRVT]) via a nasogastric tube in 18 mechanically ventilated critically ill trauma patients (mean age ± SEM 51.31 ± 4.92 years). Step II. One gram of paracetamol was delivered via the nasogastric tube, and blood samples were drawn at time (t) 0 and 30, 60 and 90 min post paracetamol administration. The paracetamol was administered immediately after step I. Step III. A try (commercial liquid food) of peros feed was given in all studied patients right after the 90 min blood sample was drawn.

All patients were divided in two groups. Group A (n = 10): patients tolerated the peros feeding and were successfully fed peros thereafter. Group B (n = 8): patients not tolerated the peros feeding. The peros feeding was not achieved the day of the study.

Results

The mean (± standard error) GRV and paracetamol serum levels were as presented in Table 1. In all Group A patients the residual gastric volume was ≤ 100 ml (mean ± standard error = 58.0 ± 9.5), whereas in all Group B patients it always was > 100 ml (mean ± standard error = 208.0 ± 18.7). All Group A patients were successfully fed whereas no one of the Group B was successfully fed the day of the study.

Table 1
Full size table

No statistically significant differences (Mann–Whitney U test) were observed in blood paracetamol levels between groups at baseline, 30 and 60 min. A statistically significant difference was observed at 90 min, reflecting the higher blood paracetamol levels of Group A, which was the successfully peros-fed group.

Conclusions

The GRVT is a fast (within 1 hour) clinical tool for decision making to peros feed a critically ill patient. A gastric residual volume < 100 ml is indicative of a successful peros feeding in our critically ill patients. The higher paracetamol blood levels at 90 min post paracetamol administration does not seem to be a useful tool in the peros feeding decision-making process. It happens because on one hand it is a time-consuming and work-consuming process and on the other hand there is not a cutoff paracetamol serum level, which separates the peros food-tolerating patients.