ALTERATIONS IN NEONATAL RESPIRATORY FUNCTION FOLLOWING CHEST PHYSIOTHERAPY

Abstract

Percussion, suctioning and hyperventilation have been recommended for airway management in neonates requiring endotracheal tubes. To investigate physiological alterations in respiratory function due to chest physiotherapy, we measured arterial blood gases, respiratory patterns, lung mechanics, and functional residual capacity (FRC) in 10 neonates, weights (1.25 to 3.20 kg) during the control period, post vibration of the chest and suctioning, after hyperventilation, and 2 hours post suctioning. Post suctioning compared to controls mean (± SEM) PaO2 decreased 75.2 (± 9.3) to 44.0 (±3.1) mm Hg (P<0.01) while lung compliance and FRC were unchanged. There was a decrease in inspiratory resistance (RI) from 81.8 (± 14.6) to 59.0 (± 10.6) cm H2O/L/sec. (P<0.02) and I:E ratio increased from 0.93 (± 0.04) to 1.04 (± 0.06) (P<0.07). Hyperventilation compared to post suctioning resulted in an increase in mean (± SEM) PaO2 to 63.9 (± 10.0) mmHg (P<0.01), and RI to 98.3 (± 22.0) cm H2O/L/sec. (P<0.05). FRC, CL, VT were unchanged. Two hour followup values for all parameters studied were similar to control values except for a trend toward increased compliance. There were no significant differences at any stage of the study for PaCO2, pH, base excess, VT, or minute ventilation. This study indicates that there is a significant decrease in PaO2 after chest vibration and suctioning increase in PaO2 after hyperventilation but these changes do not appear to be related to alterations in lung volume.