Interatrial Pressure Difference During Inflation of Pneumatic Antishock Garments and Positive End-Expiratory Pressure Ventilation

Abstract

Since an increase in the right atrial pressure (RAP) above the left atrial pressure (LAP) may then lead to paradoxical air embolism, the efficacy of pneumatic antishock garments (PASGs) and ventilation with positive end-expiratory pressure (PEEP) in preventing increases in the RAP above the LAP was investigated during neurosurgical procedures. We examined the RAP and pulmonary capillary wedge pressure (PCWP) of 25 patients during neurosurgery of the posterior fossa. Each set of measurements of PCWP and RAP included measurements during induction of anesthesia in the supine position and the seated position prior to surgery. The PCWP and RAP were recorded during PEEP = 0 cm H2O, PEEP = 10 cm H2O, or with PASG inflation to pressures ranging from 40 to 80 mm Hg. The RAP increased from 8 +/- 6 to 20 +/- 7 mm Hg (PASG) and to 11 +/- 5 mm Hg (PEEP) in the seated position without a significant (p >0.05) change in the PCWP-RAP difference under any of the above conditions. We conclude that PASGs are a safer and more effective means of raising the RAP than PEEP ventilation during seated neurosurgical procedures without the danger of paradoxical air embolism.