Establishing Coronary Patency: A Key to Optimal Post Resuscitation Care

The formalizing post resuscitation care to include therapeutic hypothermia and cardiac angiography with percutaneous coronary intervention when needed could significantly improve survival following cardiac arrest. Any sudden death patient suspected to have a cardiac origin for their cardiac arrest should be considered for early catheterization and subsequent percutaneous coronary intervention (PCI) if a culprit lesion can be identified. Successful PCI improves survival to hospital discharge and cerebral performance category in patients with or without ST elevation. Current ‘report carding’ methodology needs to be changed regarding those resuscitated from cardiac arrest (patients with cardiac arrest not including them in any statistical reporting on PCI mortality report cards)

Optimum Compression to Ventilation Ratios in CPR Under Realistic, Practical Conditions: a physiological and mathematical analysis

Objective: To develop and evaluate a practical formula for the optimum ratio of compressions to ventilations in CPR. The optimum value of a parameter is that for which a desired result is maximized. Here the desired result is assumed to be either oxygen delivery to peripheral tissues or a combination of oxygen delivery and waste product removal. Method: Equations describing oxygen delivery and blood flow during CPR as functions of the number of compressions and the number of ventilations delivered over time were developed from principles of classical physiology. These equations were solved explicitly in terms of the compression/ventilation ratio and evaluated for a wide range of conditions using Monte Carlo simulations. Results: As the compression to ventilation ratio was increased from zero to 50 or more, both oxygen delivery and the combination of oxygen delivery with blood flow increased to maximum values and then gradually declined. For parameters typical of standard CPR as taught and specified in international guidelines, maximum values occurred at compression/ventilation ratios near 30:2. For parameters typical of actual lay rescuer performance in the field, maximal values occurred at compression/ventilation ratios near 60:2 Conclusion: Current guidelines overestimate the need for ventilation during standard CPR by two to four-fold. Blood flow and oxygen delivery to the periphery can be improved by eliminating interruptions of chest compression for these unnecessary ventilations

Interposed abdominal compression as an adjunct to cardiopulmonary resuscitation

The addition of interposed abdominal compression (IAC) to otherwise standard CPR provides external pressure over the abdomen in counterpoint to the rhythm of chest compression. Interposed abdominal compression is a simple manual technique that can supplement the use of adrenergic drugs to increase both coronary perfusion pressure and total blood flow during CPR. Mechanistically, manual abdominal compressions induce both central aortic and central venous pressure pulses. However, owing to differences in venous versus arterial capacitance, the former are usually greater than the latter, so that systemic perfusion pressure is enhanced. Moreover, practical experience and theoretical analysis have suggested subtle refinements in the hand position and technique for abdominal compression that may further improve the ratio of arterial to venous pressure augmentation. Clinical studies confirm that IAC-CPR can improve perfusion pressures and carbon dioxide excretion during CPR in humans. The incidence of abdominal trauma, regurgitation, or other complications is not increased by IAC. Randomized trials have shown that short-term and long-term survival of patients resuscitated in the hospital by IAC-CPR are about twice that of control patients resuscitated by standard CPR. The technique of IAC has thus evolved to become a highly promising adjunct to normal CPR, which is likely to be implemented in an increasing number of clinical protocols

The Role of Cardiac Catheterization after Cardiac Arrest

Coronary angiography after cardiac arrest is important to ascertain potential treatable causes of cardiac arrest, salvage myocardium, and potentially increase long-term survival. The cause of adult out-of-hospital cardiac arrest is typically myocardial ischemia. More than 50% of such resuscitated individuals will have an acutely occluded epicardial coronary on emergency coronary angiography. This includes three in four with ST-segment elevation and one in three without ST-segment elevation. In the latter the only reliable method of detection is coronary angiography. Numerous cohort studies, now including more than 8000 patients, have shown an association between survival and early coronary angiography and/or percutaneous coronary intervention. Public reporting of percutaneous coronary intervention 30-day mortality rates has been an impediment for extending this therapy to all resuscitated individuals who experienced out-of-hospital cardiac arrest, since current databases to do fully risk-adjust rates for this subgroup. Sincere efforts are under way to correct this situation

Myocardial Perfusion Pressure: A Predictor of 24Hour Survival During Prolonged Cardiac Arrest in Dogs

Myocardial perfusion pressure, defined as the aortic diastolic pressure minus the right atria1 diastolic pressure, correlates with coronary blood flow during cardiopulmonary resuscitation (CPR) and predicts initial resuscitation success. Whether this hemodynamic parameter can predict 24-h survival is not known. We examined the relationship between myocardial perfusion pressure and 24-h survival in 60 dogs that underwent prolonged (20 min) ventricular fibrillation and CPR. Forty-two (70%) animals were initially resuscitated and 20 (33%) survived for 24 h. Myocardial perfusion pressure was significantly greater when measured at 5, 10, 15 and 20 min of ventricular fibrillation in the resuscitated animals than in the non-resuscitated animals (P \u3c 0.01). Likewise, the myocardial perfusion pressure was also greater in the animals that survived 24 h than in animals that were resuscitated, but died before 24 h (P \u3c 0.02). Myocardial perfusion pressure measured after 10 min of CPR was 11 2 mmHg in animals never resuscitated, 20 3 mmHg in those resuscitated that died before 24 h and 29 2 mmHg in those that survived 24 h (P \u3c 0.05). A myocardial perfusion pressure at 10 min of CPR of 20 mmHg or less is an excellent predictor of poor survival (negative predictive value = 96%). Myocardial perfusion pressure is a useful index of CPR effectiveness and therefore may be a useful guide in helping to optimize resuscitation efforts

Changes in Expired End-Tidal Carbon Dioxide During Cardiopulmonary Resuscitation in Dogs: A Prognostic Guide for Resuscitation Efforts

Expired end-tidal carbon dioxide (PCO2) measurements made during cardiopulmonary resuscitation have correlated with cardiac output and coronary perfusion pressure when wide ranges of blood flow are included. The utility of such measurements for predicting resuscitation outcome during the low flow state associated with closed chest cardiopulmonary resuscitation remains uncertain. Expired end-tidal PCO2 and coronary perfusion pressures were measured in 15 mongrel dogs undergoing 15 min of closed chest cardiopulmonary resuscitation after a 3 min period of untreated ventricular fibrillation. In six successfully resuscitated dogs, the mean expired end-tidal PCO2 was significantly higher than that in nine nonresuscitated dogs only after 14 min of cardiopulmonary resuscitation (6.2 ± 1.2 versus 3.4 ± 0.8 mmHg; p \u3c 0.05). No differences in expired end-tidal PCO2 values were found at 2, 7 or 12 min of cardiopulmonary resuscitation. A significant decline in end-tidal PCO2 levels during the resuscitation effort was seen in the nonresuscitated group (from 6.3 ± 0.8 to 3.4 ± 0.8 mmHg; p \u3c 0.05); while the successfully resuscitated group had constant PCO2 levels throughout the 15 min of cardiac arrest (ranging from 6.8 ± 1.1 to 6.2 ± 1.2 mmHg). Changes in expired PCO2 levels during cardiopulmonary resuscitation may be a useful noninvasive predictor of successful resuscitation and survival from cardiac arrest

Myocardial dysfunction after resuscitation from cardiac arrest: An example of global myocardial stunning

AbstractObjectives. This study investigated the effect of prolonged cardiac arrest and subsequent cardiopulmonary resuscitation on left ventricular systolic and diastolic function.Background. Cardiac arrest from ventricular fibrillation results in cessation of forward blood flow, including myocardial blood flow. During cardiopulmonary resuscitation, myocardial blood flow remains suboptimal. Once the heart is defibrillated and successful resuscitation achieved, reversible myocardial dysfunction, or “stunning,” may occur. The magnitude and time course of myocardial stunning from cardiac arrest is unknown.Methods. Twenty-eight domestic swine (26 ± 1 kg) were studied with both invasive and noninvasive measurements of ventricular function before and after 10 or 15 min of untreated cardiac arrest. Contrast left ventriculograms, ventricular pressures, cardiac output, isovolumetric relaxation time (tau) and transthoracic Doppler-echocardiographic studies were obtained.Results. Twenty-three of 28 animals were successfully resuscitated and postresuscitation data obtained. Left ventricular ejection fraction showed a significant reduction 30 min after resuscitation (p < 0.05). Regional wall motion analysis revealed diffuse, global left ventricular systolic dysfunction. Left ventricular end-diastolic pressure increased significantly in the postresuscitation period (p < 0.05). Isovolumetric relaxation time (tau) was significantly increased over baseline by 2 h after resuscitation (p < 0.05). Similar findings were noted with the Doppler-echocardiographic analysis, including a reduction in fractional shortening (p <0.05), a reduction in mitral valve deceleration time (p < 0.05) and an increase in left ventricular isovolumetric relaxation time in 5 h after resuscitation (p < 0.05). By 24 h, these invasive and noninvasive variables of systolic and diastolic left ventricular function had begun to improve. At 48 h, all measures of left ventricular function had returned to baseline levels.Conclusions. 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

Gasping in Response to Basic Resuscitation Efforts: Observation in a Swine Model of Cardiac Arrest

Objective. To analyze the effect of basic resuscitation efforts on gasping and of gasping on survival. Methods. This is secondary analysis of a previously reported study comparing continuous chest compressions (CCC CPR) versus chest compressions plus ventilation (30:2 CPR) on survival. 64 swine were randomized to 1 of these 2 basic CPR approaches after either short (3 or 4 minutes) or long (5 or 6 minutes) durations of untreated VF. At 12 minutes of VF, all received the same Guidelines 2005 Advanced Cardiac Life Support. Neurologically status was evaluated at 24 hours. A score of 1 is normal, 2 is abnormal, such as not eating or drinking normally, unsteady gait, or slight resistance to restraint, 3 severely abnormal, where the animal is recumbent and unable to stand, 4 is comatose, and 5 is dead. For this analysis a neurological outcome score of 1 or 2 was classified as “good”, and a score of 3, 4, or 5 was classified as “poor.” Results. Gasping was more likely to continue or if absent, to resume in the animals with short durations of untreated VF before basic resuscitation efforts. With long durations of untreated VF, the frequency of gasping and survival was better in swine receiving CCC CPR. In the absence of frequent gasping, intact survival was rare in the long duration of untreated VF group. Conclusions. Gasping is an important phenomenon during basic resuscitation efforts for VF arrest and in this model was more frequent with CCC-CPR