Revista médica de Chile
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Revista médica de Chile · Mar 1989
Review[Cardiopulmonary resuscitation: acid-base alterations and alkalizing therapy].
It is generally believed that metabolic acidosis prevails during cardiac arrest. However, recent experimental and clinical studies have demonstrated that respiratory acidosis in mixed venous blood and respiratory alkalosis in arterial blood with only minor increases in lactic acid characterize the early acid-base changes that follow cardiac arrest and cardiopulmonary resuscitation (CPR). While continued CO2 production with critical reduction in systemic perfusion explains the accumulation of CO2 in the venous side, the reduction of pulmonary blood flow with maintenance of constant minute ventilation explains the decreases in expired CO2 and therefore arterial PCO2. ⋯ Moreover, adverse effects stemming from increases in plasma osmolality, increases in hemoglobin-O2 affinity, induction of alkalemia and generation of CO2 are potentially deleterious for myocardial and cerebral function. Consequently, the American Heart Association has recently discouraged the routine administration of bicarbonate during the initial 10 minutes of CPR in which interventions with proven efficacy such as artificial ventilation, precordial compression, electric defibrillation and epinephrine administration take place. Alternative experimental buffer therapy with agents that consume CO2 have also failed to alter the outcome of cardiac arrest.