Cardiopulmonary changes in the crying neonate.

To determine hemodynamic effects of crying, 12 newborn infants recovering from the respiratory distress syndrome (RDS) were studied. When crying, the range of inspiratory esophageal pressure was -18.8 to -32.5 cm H2O and the range of espiratory pressure was +6.2 to 34.4 cm H2O. The esophageal pressure remained positive for a mean value of 66% of the respiratory cycle. There was a mean significant increase in heart rate of 19 beats/min. The systolic and diastolic blood pressures increased significantly at the beginning of strain to 115 and 135% of the respective control values. There was a progressive decrease in systolic and diastolic pressures during the period of strain and the systolic pressures reached values significantly less than control. With the decrease in systolic and diastolic pressures, there were pronounced reductions in pulse pressures. Three infants reached pulse pressure values less than 1% of control when cries were sustained for nine cardiac cycles. There was a significant mean decrease in arterial oxygen tension (PaO2) of 16.8 mm Hg. There were no changes in arterial carbon dioxide tension (PaCO2), pH, or base excess.