TRACHEAL BAROTRAUMA IN VERY PRETERM NEONATES

Abstract

Proximal airways of very preterm neonates (<32 weeks of gestation) are highly compliant structures and are susceptible to pressure-induced deformation. In previous studies we have documented tracheal barotrauma in the preterm animal model (rabbit pups and lambs). These studies have defined increases in tracheal dimensions and decreases in tracheal compliance consequent to positive pressure application. These changes are associated with a propensity towards collapsibility and are similar to those observed with tracheomalacia. Tracheal volume deformation was measured in 16 very preterm neonates 6-8 days after extubation. The mean ± SD values of birthweight and gestational age were 847±68 gms and 27±0.6 weeks, respectively. The study group was individually control-matched for weight and gestational age. The study group received ventilatory support for a mean of 25.4±4.9 SD Says with a BP200 pressure-limited, time-cycled ventilator®. The control group did not receive ventilatory support beyond the first hour of resuscitative efforts. By roentgenographic evaluation, the mean ± SD intrathoracic tracheal width was 2.74±0.31mm in the control group compared to 3.79±0.29mm in the study group (38%, p<0.001). A tracheal volume deformation of 91% (p<0.001) was calculated in the study group. These data are suggestive of underlying mechanical deformation of the immature tracheal wall. The resultant tracheomegaly and associated tracheomalacia would lead to increased dead space ventilation and increased work of breathing.