Background-Despite improving arterial oxygen saturation and pH, bystander cardiopulmonary resuscitation (CPR) with chest compressions plus rescue breathing (CCϩRB) has not improved survival from ventricular fibrillation (VF) compared with chest compressions alone (CC) in numerous animal models and 2 clinical investigations. Methods and Results-After 3 minutes of untreated VF, 14 swine (32Ϯ1 kg) were randomly assigned to receive CCϩRB or CC for 12 minutes, followed by advanced cardiac life support. All 14 animals survived 24 hours, 13 with good neurological outcome. For the CCϩRB group, the aortic relaxation pressures routinely decreased during the 2 rescue breaths. Therefore, the mean coronary perfusion pressure of the first 2 compressions in each compression cycle was lower than those of the final 2 compressions (14Ϯ1 versus 21Ϯ2 mm Hg, PϽ0.001). During each minute of CPR, the number of chest compressions was also lower in the CCϩRB group (62Ϯ1 versus 92Ϯ1 compressions, PϽ0.001). Consequently, the integrated coronary perfusion pressure was lower with CCϩRB during each minute of CPR (PϽ0.05 for the first 8 minutes). Moreover, at 2 to 5 minutes of CPR, the median left ventricular blood flow by fluorescent microsphere technique was 60 mL · 100 g Ϫ1 · min Ϫ1 with CCϩRB versus 96 mL · 100 g Ϫ1 · min Ϫ1 with CC, PϽ0.05. Because the arterial oxygen saturation was higher with CCϩRB, the left ventricular myocardial oxygen delivery did not differ. Conclusions-Interrupting chest compressions for rescue breathing can adversely affect hemodynamics during CPR for

Background — Interruptions to chest compression–generated blood flow during cardiopulmonary resuscitation (CPR) are detrimental. Data show that such interruptions for mouth-to-mouth ventilation require a period of “rebuilding” of coronary perfusion pressure to obtain the level achieved before the interruption. Whether such hemodynamic compromise from pausing to ventilate is enough to affect outcome is unknown. Methods and Results — Thirty swine (weight 35±2 kg) underwent 3 minutes of untreated ventricular fibrillation before 12 minutes of basic life support CPR. Animals were randomized to receive either standard airway (A), breathing (B), and compression (C) CPR with expired-gas ventilation in a 15:2 compression-to-ventilation ratio or continuous chest compression CPR. Those randomized to the standard 15:2 group had no chest compressions for a period of 16 seconds each time the 2 ventilations were delivered. Defibrillation was attempted at 15 minutes of cardiac arrest. All resuscitated animals were supported in an intensive care environment for 1 hour, then in a maintenance facility for 24 hours. The primary end point of neurologically normal 24-hour survival was significantly better in the experimental group receiving continuous chest compression CPR (12 of 15 versus 2 of 15; P <0.0001). Conclusions — Mouth-to-mouth ventilation performed by single layperson rescuers produces substantial interruptions in chest compression–supported circulation. Continuous chest compression CPR produces greater neurologically normal 24-hour survival than standard ABC CPR when performed in a clinically realistic fashion. Any technique that minimizes lengthy interruptions of chest compressions during the first 10 to 15 minutes of basic life support should be given serious consideration in future efforts to improve outcome results from cardiac arrest.

Myocardial systolic and diastolic dysfunction is severe after 10 to 15 min of untreated cardiac arrest and successful resuscitation. Full recovery of this postresuscitation myocardial stunning is seen by 48 h in this experimental model of ventricular fibrillation cardiac arrest.

Background-The incidence and significance of gasping after cardiac arrest in humans are controversial. Methods and Results-Two approaches were used. The first was a retrospective analysis of consecutive confirmed out-of-hospital cardiac arrests from the Phoenix Fire Department Regional Dispatch Center text files to determine the presence of gasping soon after collapse. The second was a retrospective analysis of 1218 patients with out-of-hospital cardiac arrests in Arizona documented by emergency medical system (EMS) first-care reports to determine the incidence of gasping after arrest in relation to the various EMS arrival times. The primary outcome measure was survival to hospital discharge.

Background-Survival after nontraumatic out-of-hospital (OOH) cardiac arrest in Tucson, Arizona, has been flat at 6%(121/2177) for the decade 1992 to 2001. We hypothesized that interruptions of chest compressions occur commonly and for substantial periods during treatment of OOH cardiac arrest and could be contributing to the lack of improvement in resuscitation outcome.

Background-The

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Objective Complete recoil of the chest wall between chest compressions during cardiopulmonary resuscitation is recommended, because incomplete chest wall recoil from leaning may decrease venous return and thereby decrease blood flow. We evaluated the hemodynamic effect of 10% or 20% lean during piglet cardiopulmonary resuscitation. Design Prospective, sequential, controlled experimental animal investigation. Setting University research laboratory. Subjects Domestic piglets. Interventions After induction of ventricular fibrillation, cardiopulmonary resuscitation was provided to ten piglets (10.7 ± 1.2 kg) for 18 mins as six 3-min epochs with no lean, 10% lean, or 20% lean to maintain aortic systolic pressure of 80–90 mm Hg. Because the mean force to attain 80–90 mm Hg was 18 kg in preliminary studies, the equivalent of 10% and 20% lean was provided by use of 1.8- and 3.6-kg weights on the chest. Measurements and Main Results Using a linear mixed-effect regression model to control for changes in cardiopulmonary resuscitation hemodynamics over time, mean right atrial diastolic pressure was 9 ± 0.6 mm Hg with no lean, 10 ± 0.3 mm Hg with 10% lean (p < .01), and 13 ± 0.3 mm Hg with 20% lean (p < .01), resulting in decreased coronary perfusion pressure with leaning. Microsphere-determined cardiac index and left ventricular myocardial blood flow were lower with 10% and 20% leaning throughout the 18 mins of cardiopulmonary resuscitation. Mean cardiac index decreased from 1.9 ± 0.2 L · M–2 · min–1 with no leaning to 1.6 ± 0.1 L · M–2 · min–1 with 10% leaning, and 1.4 ± 0.2 L · M–2 · min–1 with 20% leaning (p < .05). The myocardial blood flow decreased from 39 ± 7 mL · min–1 · 100 g–1 with no lean to 30 ± 6 mL · min–1 · 100 g–1 with 10% leaning and 26 ± 6 mL · min–1 · 100 g–1 with 20% leaning (p < .05). Conclusions Leaning of 10% to 20% (i.e., 1.8–3.6 kg) during cardiopulmonary resuscitation substantially decreased coronary perfusion pressure, cardiac index, and myocardial blood flow.