Randomized crossover comparison of proportional assist ventilation and patient-triggered ventilation in extremely low birth weight infants with evolving chronic lung disease

Background: Refinement of ventilatory techniques remains a challenge given the persistence of chronic lung disease of preterm infants. Objective: To test the hypothesis that proportional assist ventilation ( PAV) will allow to lower the ventilator pressure at equivalent fractions of inspiratory oxygen (FiO(2)) and arterial hemoglobin oxygen saturation in ventilator-dependent extremely low birth weight infants in comparison with standard patient-triggered ventilation ( PTV). Methods: Design: Randomized crossover design. Setting: Two level-3 university perinatal centers. Patients: 22 infants ( mean (SD): birth weight, 705 g ( 215); gestational age, 25.6 weeks ( 2.0); age at study, 22.9 days ( 15.6)). Interventions: One 4- hour period of PAV was applied on each of 2 consecutive days and compared with epochs of standard PTV. Results: Mean airway pressure was 5.64 ( SD, 0.81) cm H2O during PAV and 6.59 ( SD, 1.26) cm H2O during PTV ( p < 0.0001), the mean peak inspiratory pressure was 10.3 ( SD, 2.48) cm H2O and 15.1 ( SD, 3.64) cm H2O ( p < 0.001), respectively. The FiO(2) ( 0.34 (0.13) vs. 0.34 ( 0.14)) and pulse oximetry readings were not significantly different. The incidence of arterial oxygen desaturations was not different ( 3.48 ( 3.2) vs. 3.34 ( 3.0) episodes/ h) but desaturations lasted longer during PAV ( 2.60 ( 2.8) vs. 1.85 ( 2.2) min of desaturation/ h, p = 0.049). PaCO2 measured transcutaneously in a subgroup of 12 infants was similar. One infant met prespecified PAV failure criteria. No adverse events occurred during the 164 cumulative hours of PAV application. Conclusions: PAV safely maintains gas exchange at lower mean airway pressures compared with PTV without adverse effects in this population. Backup conventional ventilation breaths must be provided to prevent apnea-related desaturations. Copyright (c) 2007 S. Karger AG, Base

Lung Compliance in Newborns with Patent Ductus Arteriosus before and after Surgical Ligation

Pressure volume curves of the lungs were determined in 10 premature infants (mean gestational age 31.4 weeks, mean birth weight 1,260 g) before and after surgical ligation of a patent ductus arteriosus (PDA). 7 infants who had low compliance initially showed a significant improvement in lung compliance after surgery, while 3 infants whose compliance was close to normal before surgery had a decrease after ligation. In conclusion, a PDA with left to right shunt is frequently associated with a decrease in lung compliance that improves after ligation. Measurement of lung compliance in infants with PDA can be helpful in predicting the degree of improvement in lung function that may result from the closure of the ductus

Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia has become the most common pulmonary sequelae in neonates receiving mechanical ventilation. The pathogenesis of BPD is multifactorial, but prematurity, positive pressure ventilation, oxygen toxicity and pulmonary edema are some of the most important factors in its development. By minimizing these factors, it is possible to reduce the incidence and severity of BPD

CHESTWALL COMPLIANCE IN FULL‐TERM AND PREMATURE INFANTS

. Gerhardt, T. and Bancalari, E. (Department of Pediatrics, University of Miami, Florida, U.S.A.) Chestwall compliance in full‐term and premature infants. Acta Pediatr Scand, 69: 359, 1980.—Chestwall compliance was determined in 26 premature infants (BW 1 320±410 g, gest. age 32 weeks) and in 10 full‐term infants (BW 3 155±810 g) who were ventilated mechanically. Chestwall compliance in premature infants was 6.4 ml/ (cmH2O×kg), decreasing with advancing gestational age to 4.2 ml/(cmH2O×kg) in full‐term infants. There was a linear correlation (r= 0.95 and 0.79 respectively) between tidal volume and the pressure transmitted to the esophagus throughout the tidal volume range. The portion of airway pressure transmitted to the esophagus depended on the infant's lung compliance. Only 5% was transmitted in infants with hyaline membrane disease, 12% in newborns with a patent ductus arteriosus, 17 % in normal prematures and 25% in normal full‐term infants. The findings suggest that during mechanical ventilation the high chestwall compliance and low lung compliance of premature infants prevent a significant rise in intrapleural pressure which could interfere with central venous return and cardiac output. However, using high inspiratory pressures and continuous distending airway pressure in the absence of lung pathology may result in a decreased cardiac output. The highly compliant chestwall of the premature infant may exert insufficient outward recoil and might be one of the causes of a low functional residual capacity and chronic pulmonary failure in the premature infant