The effect of rapid thoracoabdominal compressions on intracranial pressure in newborn lambs

Measurements of forced expiratory flow in infants can be obtained with the rapid thoracoabdominal compression (RTC) technique. To assess the transmission of the chest wall compression pressure into the cerebrum, we have performed intracranial pressure (ICP) measurements during RTCs in newborn lambs. Thirteen lambs were studied during the first 8 d of life. An epidural pressure transducer was implanted under general anesthesia. Respiratory measurements were performed under sedation with ketamine. RTCs were induced through an inflatable jacket wrapped around the lamb's trunk. RTCs were started with a pressure of 30 cm H2O. The compression pressure was increased in steps of 20 cm H2O up to 250 cm H2O. Flow and volume were determined with a pneumotachograph attached to a face mask. Transpulmonary pressure (Ptp) was measured with an esophageal balloon placed in the lower esophagus. RTCs resulted in proportional increases of Ptp and ICP. ICP was lower or equal to Ptp in all measurements. No changes in baseline ICP occurred throughout the study period. The maximal ICP observed during RTCs was within the range of pressures observed during crying in newborn infants. These data suggest that the RTC technique can be considered safe even at high compression pressures.