Abstract
BackgroundPositive end-expiratory pressure (PEEP) is used to optimize oxygenation by preventing alveolar collapse. However, PEEP can potentially decrease cardiac output through cardiopulmonary interactions. The effect of PEEP on cardiac output during cardiopulmonary resuscitation (CPR) is not known.MethodsThis was a preclinical randomized, controlled, animal study conducted in an animal research facility on 25 Landrace-Yorkshire pigs. After inducing cardiac arrest, CPR was performed with LUCAS 3. During CPR, pigs were ventilated at a PEEP of 0, 5, 10, 15, 20 cmH2O (randomly determined via lottery) for 9 min. Cardiac output, obtained via ultrasound dilution, and PaO2 were measured, and oxygen delivery calculated for each PEEP.ResultsA mixed-effects repeated-measures analysis of variance was used to compare the baseline value adjusted mean cardiac output, PaO2, and oxygen delivery between PEEP groups. Least significant difference test was used to conduct pairwise comparisons between PEEP groups. To determine optimum PEEP, Gaussian mixture model was applied to the adjusted means of cardiac output and oxygen delivery. Increasing PEEP to 10 and higher resulted in significant declines in cardiac output. A PEEP of 15 and higher resulted in significant declines in oxygen delivery. As PEEP was increased from 0 to 20, PaO2 increased significantly. Gaussian mixture model identified the 0–5 PEEP group as providing optimal cardiac output and oxygen delivery, with PEEP of 5 providing the highest oxygen delivery.ConclusionsA PEEP of 0–5 resulted in the optimal oxygen delivery and cardiac output during CPR, with PEEP of 5 resulting in higher oxygen delivery, and a slightly lower, statistically insignificant cardiac output than PEEP of 0.
Highlights
Positive end-expiratory pressure (PEEP) is used to optimize oxygenation by preventing alveolar collapse
No significant difference in mean cardiac output (CO) was observed between PEEP levels 10 and 15 cmH2O
The results of this study demonstrate that as PEEP is increased from 0 to 20 cmH2O, there is a significant decline in CO and Oxygen delivery (DO2)
Summary
Positive end-expiratory pressure (PEEP) is used to optimize oxygenation by preventing alveolar collapse. PEEP can potentially decrease cardiac output through cardiopulmonary interactions. The effect of PEEP on cardiac output during cardiopulmonary resuscitation (CPR) is not known. When providing positive pressure ventilation, PEEP is used to prevent alveolar collapse, improve lung compliance, increase functional residual capacity, and maintain the adequate surface area of the lung for oxygen delivery (DO2) [1]. Some believe, based on older studies, that during CPR, PEEP can potentially lead to a decline in cardiac output (CO) through a complex series of cardiopulmonary interactions [3, 4]. Some providers remain hesitant to supply any PEEP during CPR due to a concern that the potential decrease in CO caused by the use of PEEP will offset the benefit gained by improved gas exchange [2, 6]. We sought to evaluate the effect of PEEP on CO, PaO2, and DO2 during CPR to determine the optimum PEEP for CO, PaO2, and DO2 to the tissues during CPR
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