Mechanism To Coronary Perfusion Pressure In Closed-chest Cardiopulmonary Resuscitation

Objectives:We aimed to study the relationship among aortic pressure (AOP), right atrial pressure (RAP) and coronary perfusion pressure (CPP) during manual, closed-chest cardiopulmonary resuscitation (CPR), the relation with survival and underling implication to clinical practice.Methods:In total,23 domestic dogs (12-18 kg) underwent standard manual CPR after 12 min of untreated ventricular fibrillation (VF). AOP and RAP were recorded continuously for the first 2 min of CPR; CPP was calculated as the gradient of (AOP-RAP) simultaneously.Results:The relationship among AOP, RAP and CPP in CPR during the first 2 min of CPR was of 2 types. In type 1, AOP and RAP were comparable during the compression phase, which resulted in a relatively low CPP. In type 2, AOP was higher than RAP, for a high CPP during compression. CPP peaked in different phases in the 2 types. For type 1, CPP was positive during decompression (17.50±17.37 mmHg) but became negative during compression (-0.21±18.36 mmHg); however in type 2, CPP was higher during compression than decompression (29.93±25.62 vs. 4.00±12.52 mmHg). These contrary hemodynamic relationships were associated with short-term survival, with type 2 associated with better outcome (p=0.039).Conclusions:Two categories of distinct pressure relationships occur during manual closed-chest CPR in a prolonged (12-min) VF model, and these hemodynamic relationships have a great impact on survival. Conventional CPP calculation during the decompression phase in closed-chest CPR should be reconsidered carefully.