Ma. Ritz et al., Delayed gastric emptying in ventilated critically ill patients: Measurement by C-13-octanoic acid breath test, CRIT CARE M, 29(9), 2001, pp. 1744-1749
Objective: To measure gastric emptying in ventilated critically ill patents
with a new noninvasive breath test.
Design: Single-center, open study.
Setting: Combined medical and surgical intensive care unit of a university
hospital.
Subjects: Thirty unselected mechanically ventilated critically ill patients
receiving gastric feeding and 22 healthy volunteers.
Interventions: None.
Patients: After 4 hrs without feeding, intragastric infusion of 100 mL of a
liquid meal (Ensure) labeled with 100 muL C-13-octanoic acid. End-expirato
ry breath samples were collected into evacuated tubes from the respirator c
ircuit every 5 mins for the first hour, then every 15 mins for 3 hrs. End-e
xpiratory breath samples were also collected from volunteers studied supine
after an overnight fast following an identical infusion via a nasogastric
tube. Breath (CO2)-C-13 was measured with an isotope ratio mass spectromete
r.
Measurements and Main Results: Performance of the breath test posed no diff
iculty or interference with patient care. The CO2 level was >1% in 1297/130
0 breath samples, indicating satisfactory end-expiratory timing. Data are m
edian and interquartile range. Gastric emptying was slower in patients comp
ared with volunteers: gastric emptying coefficient 2.93 (2.17-3.39) vs. 3.5
8 (3.18-3.79), p < .001 and gastric half emptying time, derived from the ar
ea under the (CO2)-C-13 curve, 155 min (130-220) vs. 133 min (120-145), p <
.008. Fourteen of the 30 patients had a gastric emptying coefficient < 95%
of all volunteers and 11 had a gastric half emptying time longer than 95%
of all volunteers. The Acute Physiology and Chronic Health Evaluation (APAC
HE II) score (median 22, range 13-43) either at admission or on the day of
the study did not correlate with gastric emptying coefficient.
Conclusion: Gastric emptying of a calorie-dense liquid meal is slow in 40%
to 45% of unselected mechanically ventilated patients in a combined medical
and surgical intensive care unit. The C-13-octanoic acid breath test is a
novel and useful bedside technique to measure gastric emptying in these pat
ients.