Delayed gastric emptying in ventilated critically ill patients: measurement by 13 C-octanoic acid breath test.
OBJECTIVE
To measure gastric emptying in ventilated critically ill patients with a new noninvasive breath test.


METHODS
Single-center, open study.


METHODS
Combined medical and surgical intensive care unit of a university hospital.


METHODS
Thirty unselected mechanically ventilated critically ill patients receiving gastric feeding and 22 healthy volunteers.


METHODS
None.


METHODS
After 4 hrs without feeding, intragastric infusion of 100 mL of a liquid meal (Ensure) labeled with 100 microL 13C-octanoic acid. End-expiratory breath samples were collected into evacuated tubes from the respirator circuit every 5 mins for the first hour, then every 15 mins for 3 hrs. End-expiratory breath samples were also collected from volunteers studied supine after an overnight fast following an identical infusion via a nasogastric tube. Breath 13CO2 was measured with an isotope ratio mass spectrometer.


RESULTS
Performance of the breath test posed no difficulty or interference with patient care. The CO2 level was >1% in 1297/1300 breath samples, indicating satisfactory end-expiratory timing. Data are median and interquartile range. Gastric emptying was slower in patients compared with volunteers: gastric emptying coefficient 2.93 (2.17-3.39) vs. 3.58 (3.18-3.79), p <.001 and gastric half emptying time, derived from the area under the 13CO2 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 (APACHE II) score (median 22, range 13-43) either at admission or on the day of the study did not correlate with gastric emptying coefficient.


CONCLUSIONS
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 13C-octanoic acid breath test is a novel and useful bedside technique to measure gastric emptying in these patients.
Ritz
M A
MA
Department of Gastrointestinal Medicine, Royal Adelaide Hospital, Adelaide, South Australia, Australia.
Fraser
R
R
Edwards
N
N
Di Matteo
A C
AC
Chapman
M
M
Butler
R
R
Cmielewski
P
P
Tournadre
J P
JP
Davidson
G
G
Dent
J
J
D018806:APACHE; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001944:Breath Tests / Q000379:methods; D002210:Caprylates / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry*; D016022:Case-Control Studies; D003422:Critical Care; D004750:Enteral Nutrition; D005260:Female; D005746:Gastric Emptying; D006801:Humans; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial
D002210:Caprylates; D002245:Carbon Dioxide; C031492:octanoic acid