Could Carbon Breath Test Measurement Accurately Reflect Gastric Emptying of Liquid Nutrient Meal in the Critically Ill Patients? (Gut 2011;60:1336-1343)

Abstract

It is assumed that delayed gastric emptying (GE) occurs frequently in critically ill patents, but the overall prevalence of delayed GE in these patients using scintigraphy remains uncertain. Recently Chapman et al1 reported that GE was demonstrated to be slow in about 50% of intensive care unit patient using scintigraphy and the breath test appears to be an accurate alternative to scintigraphy for the measurement of GE in critically ill patients. Studies were performed in the 25 unselected, mechanically ventilated patients and 14 healthy controls. A nasogastric (NG) tube was inserted to all of healthy controls for the purpose of the study and its position was verified by pH measurement of NG tube aspirates. Prior to the study, the gastric contents were aspirated and a test meal which consisted of 100 mL Ensure (1 kcal/mL) doped with 20 MBq 99mTechnetium sulphur colloid and 75 KBq octanoic acid, [1-14C] sodium salt was infused into the stomach via the NG tube over 5 minutes. The scintigraphic measurement of GE was performed in patients and healthy controls using a mobile γ camera with 3 minute dynamic frame acquisition. Gastric meal retention (scintigraphy) at 60, 120, 180 and 240 minutes, breath test t50 (BT50) and GE coefficient were determined. Before and after the study, the gastric residual volume (GRV) was determined every 6 hour and the total volumes were documented for 24 hour preceding the study. The authors demonstrated that, of the 24 patients with scintigraphy data, GE was delayed at 120 minutes in about 50% of intensive care unit patients. Patients with delayed GE had greater severity of illness on admission to the intensive care unit, and were more likely to have been admitted with trauma, sepsis and respiratory failure. Breath tests correlated well with scintigraphy in both patients and healthy controls (% retention at 120 minutes vs BTt50; r2 = 0.57 healthy; r2 = 0.56 patients; P ≤ 0.002 for both). There was also a strong correlation between breath measurements and intragastric retention in both patients and healthy controls. In patients with slow GE there was a trend for a reduced volume nutrient delivery, and energy delivery was reduced in the patients with slow GE (normal GE 1,920 vs slow GE 510 kcal; P = 0.047). Therefore, they concluded that GE was delayed in about half of critically ill patients and markedly delayed in about 20%, and breath tests correlated well with scintigraphy and could be used as a valid method for the measurement of GE in these patients for research purposes to quantify the effects of promotility agents.