Primordial conditions of successful resuscitation: experimental study

In anesthetized dogs blood pressure (BP), carotid artery flow (CAF), oxygen tension of arterial blood (PaO2) and brain surface (bs-PO2), ECG, and frequency-analyzed EEG were measured and recorded. The changes in these parameters were detected in the control state and during ventricular fibrillation with external and direct heart massage as well as after defibrillation. Comparisons were made between the effect of oxygen and room air ventilation. The degree of successful resuscitation was 88% with direct heart massage and O2 respiration, 76% with external thoracic massage and O2 ventilation, and 68% with external massage combined with room air respiration. The highest BP and CAF could be achieved with direct heart massage. The results suggest the following: the minimal requirement for success is to achieve a BP of 5 kPa 40 mmHg and 13 ml/min CAF. In cases of dogs with a large and stiff thorax, this minimal pressure and flow cannot be ensured. During effective massage with room air ventilation, the brain surface PO2 increases moderately, but with O2-respiration it returns to normal. Small or no change in brain surface PO2 indicates an unfavorable prognosis. The start of brain surface PO2 elevation coincides with the reappearance of the first EEG waves, but the bs-PO2 increase precedes the normalization of EEG.