Restoring Coronary Perfusion Pressure before Defibrillation after Chest Compression Interruptions

Background: Sufficient coronary perfusion pressure (CPP) to provide myocardial reperfusion is required for defibrillation success after prolonged ventricular fibrillation (VF) cardiac arrest. Chest compression interruptions cause a precipitous drop in CPP. Objective: To quantify the ex- tent to which CPP recovers to pre-pause levels following chest compression interruptions. Me- thods: This was a secondary analysis of data from two similar IACUC approved protocols. A total of 105 Yorkshire swine were included and VF was electrically induced. 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). Our primary outcome was defined as the ratio of CPP recovery (CPP3- CPP2) to the drop in CPP (CPP1-CPP2). Results: Interrupting compressions resulted in a significant drop in CPP (29.8 mmHg [95%CI: 26.2, 33.4] to 6.8 mmHg [95%CI: 5.4, 8.2]). Resuming CPR for restored 83% (95%CI: 78%, 86%) of the CPP lost. Conclusion: This study demonstrates that 83% of the decline in CPP values during a planned 10-second interruption in CPR can be restored with a short period of precordial compressions prior to defibrillation.

Coronary Perfusion Pressure Response to High-Dose Intraosseous versus Standard-Dose Intravenous Epinephrine Administration after Prolonged Cardiac Arrest

Background: This study was done to compare coronary perfusion pressure (CPP) prior to the first rescue shock (RS) among a group of animals that received intraosseous (IO) epinephrine 0.1 mg/ kg (high-dose epinephrine [HDE]) with a group that received intravenous (IV) epinephrine 0.01 mg/kg (standard-dose epinephrine [SDE]) during cardiac arrest resuscitation using a swine model of prolonged out-of-hospital ventricular fibrillation (VF) cardiac arrest. Methods: This was a secondary analysis of prospectively collected data from two IACUC approved protocols. Seventy-nine Yorkshire swine (25 - 35 kg) were surgically instrumented under anesthesia and VF was electrically induced. After 10 minutes of untreated VF in the IO study (n = 26) and 12 minutes of untreated VF in the IV study (n = 53), resuscitation commenced with closed chest compressions (CCC). A single dose of epinephrine (HDE IO or SDE IV, respectively) was given and flushed with saline. The CCC and RS attempts were standardized for all animals. The CPP was defined as aortic diastolic pressure minus right atrial diastolic pressure measured 2.5 minutes after medication delivery. Descriptive statistics were used to analyze the data. Results: Baseline group characteristics were mathematically the same. Just prior to the first RS, HDE IO resulted in a mean CPP of 33.2 mmHg (95%CI: 26.6, 39.9), while SDE IV resulted in a mean CPP of 25.0 mmHg (95%CI: 20.5, 29.4). Conclusion: This observation study reaffirms the assertion that HDE IO may be required to generate CPP values similar to SDE IV during resuscitation of prolonged VF.