Coronary perfusion pressure (CPP), also
known as simply perfusion pressure, refers to the pressure gradient that drives
coronary blood pressure, meaning the difference between the diastolic aortic
pressure and the left ventricular end diastolic pressure. Sufficient CPP to
provide myocardial reperfusion is required for defibrillation success after
prolonged ventricular fibrillation (VF) cardiac arrest. However, when chest compression interruptions occur during cardiopulmonary
resuscitation (CPR), there is a precipitous and sustained loss of CPP. The
purpose of this study was to quantify the extent
to which CPP recovers to pre-pause levels following chest compression
interruptions.
This was a secondary
analysis of prospectively collected data from two similar IACUC approved
protocols. Animal handling and all surgical procedures were in strict
compliance with the NIH Guide for the Care and Use of Animals. Both studies
were conducted in our USDA-certified laboratory. A total of 105 female
Yorkshire swine (weighing 30 - 35 kg) were included. After 10 minutes of
untreated VF in the first study (n = 52) and 12 minutes of untreated VF in the
second (n = 53), CPR began and epinephrine was administered approximately 2
minutes prior to a planned 10-second pause to record an artifact-free ECG waveform
segment. Following this pause, CPR was resumed for 20 seconds prior to
defibrillation. CPP data were extracted from three time points: 2 minutes after
epinephrine delivery (CPP1); following the chest compression pause (CPP2); and
immediately before defibrillation (CPP3). The primary outcome was defined as
the ratio of CPP recovery (CPP3- CPP2) to the drop in CPP (CPP1-CPP2).
The results
indicated that interrupting chest compressions to
analyze the ECG VF rhythm caused a significant drop in CPP from 29.8 mmHg to
6.8 mmHg. Resuming CPR for 20 seconds prior to RS delivery restored 83% (95%CI:
78%, 86%) of the CPP lost during the CPR interruption.
Article by Timothy
J. Mader, et al, from Tufts University School of Medicine, Springfield, USA.
Full access: http://mrw.so/4pxQby
Image by Dana Arena, from Flickr-cc.
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