The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

PRONE POSITIONING OF EXTREMELY LOW BIRTH WEIGHT INFANTS DURING MECHANICAL VENTILATION RESULTS IN HIGHER PCO2’S AND LOWER PH’S.

D. D. Woodhead1, D. K. Lambert1, N. Schmutz1, C. Allen1, J. S. Hildebrand1, V. L. Baer1, R. D. Christensen1


Background.
In general, the NICU staff change the position of each mechanically ventilated (MV) premature infant every three to four hours. We postulated that in the prone position, the chest wall is less mobile, which leads to reduced chest ventilatory excursions and decreased ventilation.

Methods. The data for this retrospective research project was collected on ninety-four premature infants that were intubated, required MV, and delivered between the gestational ages of 23 and 30 weeks at McKay-Dee Hospital during the years of 2001 to 2006. All data were collected from patient flow-sheets then divided into three weight categories (<1000 grams; 1001 – 1500 grams; and >1500 grams). Data collection included date of birth; gestational age; birth weight; infant weight for each day while on MV; ventilator mode, infant positioning, (i.e. prone, supine, right or left side down); and arterial blood pH and pCO2 in the various positions. The values were compared by unpaired Student t test. Intermountain Healthcare Institutional Review Board approved the study.

Results. When comparing the <1000 gram high frequency ventilator prone group against the remaining three positions, the pH in the prone position was 7.30+0.09 (mean+SD) compared to a pH of 7.34+0.09; P<0.0001. The 95% confidence interval (CI) for decrease in pH while prone was 0.03 to 0.05 units. The pCO2 in the prone position was 54.2+13.9 while the remaining three positions pCO2 was 47.4+11.6; P<0.0001. The 95% CI for increase in pCO2 while prone was 5.2 to 8.4 torr. When comparing the <1000 gram conventional ventilator prone group against the remaining three positions, the pH of the prone position was 7.30+0.08 compared to 7.32+0.07; P<0.0001. The 95% CI for decrease in pH while prone was 0.02 to 0.04 units. The pCO2 in the prone position was 53.2+8.6 while the remaining three positions pCO2 was 49.7+9.9; P<0.0001. The 95% CI for increase in pCO2 while prone was 1.7 to 5.3 torr. There was no statistically significance in the higher weight groups.
Conclusions. Those providing care to mechanically ventilated neonates <1000 grams should anticipate an adverse effect when positioning prone. Specifically, prone positioning should be expected to result in an increase in pCO2 and a decrease in pH.

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