Indirect calorimetry in mechanically ventilated infants and children: measurement accuracy with absence of audible airleak.

OBJECTIVE

To establish the effect of an audible airleak (around an endotracheal tube) on oxygen consumption (VO2) measurements in pediatric ICU patients.

DESIGN

Prospective trial comparing VO2 measurements before and after deflation of the endotracheal tube cuff.

SETTING

Pediatric ICU in a large pediatric tertiary care center.

PATIENTS

Twenty critically ill infants and children receiving mechanical ventilatory support via cuffed endotracheal tube.

INTERVENTIONS

Deflation of endotracheal tube cuff.

MEASUREMENTS AND MAIN RESULTS

The presence (group 1, n = 9) or absence (group 2, n = 11) of an audible airleak with the cuff deflated was confirmed by two independent observers. The percent difference in VO2 was calculated for both groups using the following formula: ([VO2 cuff up - VO2 cuff down]/VO2 cuff up) x 100. An audible airleak associated with cuff deflation (group 1) caused a significant (p = .0012) reduction of VO2 by 45.6% (mean difference in VO2 = 45.6%). In contrast, with no audible airleak after cuff deflation (group 2), only minimal changes in VO2 (mean difference in VO2 = -0.4%) were observed.

CONCLUSIONS

These data suggest that if no audible airleak is detected, VO2 determined by indirect calorimetry may be reliably measured in infants and children with a noncuffed endotracheal tube.