Effect of positive end-expiratory pressure on ductal shunting and systemic blood flow in preterm infants with patent ductus arteriosus

Abstract

Background: Left to right (L-R) shunting through a patent ductus arteriosus (PDA) can reduce systemic and cerebral blood flow in preterm infants. To minimize this, the positive end-expiratory pressure (PEEP) is often raised to increase pulmonary vascular resistance and reduce L-R shunting. The effects of this maneuver on systemic and cerebral hemodynamics and oxygenation are not well documented.

Objective: To compare the effects of different PEEP on the left ventricular output (LVO), superior vena cava (SVC) flow, LVO/SVC flow ratio, cerebral oxygenation (CrSO2) and gas exchange in mechanically ventilated preterm infants with PDA.

Methods: Sixteen mechanically ventilated infants of 23-30 weeks' gestational age with L-R shunting through the PDA were studied. Ultrasound measurements of LVO and SVC flow, CrSO2, arterial oxygen saturation and transcutaneous CO2 tension (TcPCO2) obtained at PEEP of 2 and 8 cm H2O were compared with baseline values at 5 cm H2O.

Results: There was a small but significant reduction in LVO and the LVO/SVC flow ratio at PEEP of 8 compared to 5 cm H2O. SVC flow and CrSO2 did not differ significantly.

Conclusions: Increasing PEEP to 8 cm H2O in ventilated preterm infants with a PDA produced a modest decrease in L-R ductal shunting as indicated by a lower LVO/SVC flow ratio. The higher PEEP did not have a significant effect on cerebral perfusion or oxygenation.