Physiological variables during open chest cardiopulmonary resuscitation: results from a small series.
OBJECTIVES: To evaluate the efficacy of open chest cardiac compressions for the resuscitation of pre-hospital cardiac arrest patients presenting with non-shockable rhythms on arrival at the emergency department. DESIGN: Prospective observational study of outcomes and physiological parameters during open chest cardiac compressions for non-traumatic pre-hospital cardiac arrest. SETTING: Large accident and emergency department receiving pre-hospital cardiac arrest patients with pre-hospital advanced life support provided by ambulance service paramedics. SUBJECTS: All patients in whom open chest cardiac compressions were performed by the author (JCC) during the period from January to May 1998 (seven patients). INTERVENTIONS: Assessment of artificial pulse and blood pressure generated by open chest cardiac compressions, measurement of arterial blood gases, recovery of spontaneous cardiac output, recovery of spontaneous ventilatory efforts and survival to admission and to discharge. RESULTS: Artificial pulse and recordable non-invasive blood pressures were generated in all patients; PO2 was physiological or supra-physiological in all patients; PCO2 was physiological or subphysiological in all patients; pH and base deficit were not corrected in the five patients with repeated samples (including two receiving 50 mEq sodium bicarbonate); three patients recovered spontaneous cardiac output (ROSC); two patients recovered spontaneous respiratory efforts (unrelated to ROSC); no patients survived to admission. CONCLUSIONS: Open chest cardiac compressions provide effective perfusion, enabling correction of ventilation parameters and showing clinical signs of adequate perfusion. However, acidosis was not corrected and the use of 50 mEq sodium bicarbonate was ineffective.