The physiology of external cardiac massage: high-impulse cardiopulmonary resuscitation.

Abstract

In intact chronically instrumented dogs, left ventricular dynamics were studied during cardiopulmonary resuscitation (CPR). Electromagnetic flow probes measured cardiac output and coronary blood flow, ultrasonic transducers measured cardiac dimensions, and micromanometers measured left ventricular, right ventricular, aortic, and intrathoracic pressures. The dogs were anesthetized with morphine, intubated, and fibrillated by rapid ventricular pacing. Data were obtained during manual external massage with dogs in the lateral and supine positions. Force of compression was varied from a peak intrathoracic pressure of 10 to 30 mm Hg, and compression rate was varied from 60 to 150/ min. Increasing force of compression increased stroke volume up to a peak intrathoracic pressure of approximately 20 mm Hg, beyond which stroke volume remained constant or declined. Stroke volume appeared to result primarily from direct transmission of manual compression force to the heart rather than from positive intrathoracic pressure because peak cardiac or vascular pressures or the change in these pressures were consistently two to four times greater than the corresponding intrathoracic pressures during manual compression. With increasing compression rate, stroke volume remained relatively constant, and total cardiac output increased significantly: 425 + 92 ml/min at 60/min, 643 130 ml/min at 100/min, and 975 ± 219 ml/min at 150/min (p < .05). Left ventricular dimensions decreased minimally at higher manual compression rates. In four patients undergoing CPR, systolic and diastolic arterial blood pressure increased with faster compression rates, correlating well with data obtained in the dog. Dynamic coronary blood flow in canine experiments decreased to zero or negative values during compression. Antegrade coronary flow occurred primarily during noncompression periods and seemed to be related to diastolic aortic perfusion pressure; coronary flow at a compression rate of 150/min averaged 75% of control. Therefore stroke volume and coronary blood flow in this canine preparation were maximized with manual chest compression performed with moderate force and brief duration. Increasing rate of compression increased total cardiac output while coronary blood flow was well maintained. Direct cardiac compression appeared to be the major determinant of stroke volume during manual external cardiac massage.

Physiology of blood flow during cardiopulmonary resuscitation. A transesophageal echocardiographic study.

“…In a highly instrumented dog model in studies at Duke University in 1984, compression force and rate were varied during cardiopulmonary resuscitation. 28 Using high-fidelity micromanometer catheters to measure intrathoracic pressure and coronary blood flow, the researchers found that increased compression force did not increase stroke volume and concluded that direct cardiac compression was the major determinant of stroke volume during cardiopulmonary resuscitation. In 1987, the Duke University investigators used transthoracic and transesophageal echocardiography in nine dogs to investigate mitral valve motion during cardiopulmonary resuscitation.…”

Myocardial perfusion pressure: A predictor of 24-hour survival during prolonged cardiac arrest in dogs

“…After 3 min, one of six methods of CPR was performed for 17 min including: manual American Heart Association Standard [13], High Impulse Compression [14], Interposed Abdominal Compression [15], Thumper @ performed American Heart Association Standard [13], Simultaneous Compression and Ventilation [6], or Vest CPR [8]. Each animal received only one form of CPR.…”

The Effect of Two Fingers-Chest Compression Using the Supporting Instrument During Infant Cardiopulmonary Resuscitation

“…심폐소생술 중 가슴 압박법은 흉골의 아랫부분을 리듬 감 있게 연속해서 규칙적으로 압박함으로서 흉강내의 압 력을 증가시키거나 심장이 직접 압박을 받아 순환이 발생 하게 한다 (1)(2)(3) . 미국심장협회(American Heart Association: AHA)의 2010년 가이드라인에 의하면 심정지로 인해 혈류 공급이 중단된 경우 가슴 압박 시행은 주요장기인 심장, 폐, 뇌에 혈액 순환을 공급하여 조직의 괴사 및 심정지 환 자의 생존율 향상에 영향을 미치기에 중요성을 강조하고 있다 (4) .…”