Uso de cloreto de cálcio como adjuvante na reanimação cardiopulmonar cerebral (RCPC) em cães

Abstract

Background: Treatment of cardiopulmonary arrest has been a source of discussion in both medicine as in veterinary with an emphasis on the use of solutions with calcium because of its importance as an ion essential for heart’s functionality. Only a few studies have showed the use of Ca2+ in CPCR. Based on this, the present study aimed to evaluate the use of calcium chloride as an adjuvant therapy in CPCR in dogs. Materials, Methods & Results: Eighteen cases of CPCR from the hospital routine of HCV-UFRGS were studied. Cases were selected from those in which occurred a cardiopulmonary arrest with reversal to a ventricular asystole in dogs. These animals were divided into two groups. In nine animals from the group called EPI, epinephrine was administered intravenously at a dose of 0.1 mg.kg-1 or by pulmonary route in a dose of 0.2 mg.kg-1. In the remaining nine animals, named EPIC group, the protocol was similar to the previous group, with the addition of the administration of calcium chloride 10% immediately after administration of epinephrine. In EPI group, the overall rate of success was 55.6%, and three of the cases treated showed reversion to normal sinus rhythm asystole. In the remaining six cases, four progressed to nonresponsive transient ventricular tachycardia (VT) and death, and two progressed to junctional rhythm. In the EPIC group, the overall rate of success was 22.2%. Four animals had VF from an asystole, in which in two of them were reversed by electric defibrillation, and in two of them the reversal was not obtained. In the other five treated animals, a ventricular tachycardia was developed followed by an irreversible cardiac arrest. Discussion: The incidence and prevalence of cardiac arrest diagnosed in animals in both hospitals and outpatients are still scarce data. However when it comes to patients under anesthesia, the success rate of CPCR are low compared to medicine. Calcium ion is indispensable in order to generate activation of the cardiac myofilaments to produce contraction of the heart. Cardiopulmonary arrest leads to a series of physiological changes that decrease the ability of the myocardium to maintain their automaticity and, in turn, generate a cardiac pacemaker, as well as its contractility. Several studies show that such these changes could be because of a severe hypocalcemia, found in both humans and dogs. Despite of the recent consensus against its use, calcium chloride in CPCR can increase the intracellular levels of this ion, which can cause inhibition of cellular respiration and energy production in mitochondrias, triggering an enzymatic proteolytic reaction, leading to cell death. However there is a clear exception in cases where the patient is in a framework of hypocalcemia. The EPI group has reached better rates of success; however, in the EPIC group was observed a reversal of asystole to VF, a fact that did not occur in group EPI. The treatment for VF is electric defibrillation, with a better prognosis when compared to asystole. Although the EPI group has obtained the best result and epinephrine rather is the best treatment of choice to CPCR, the EPIC group demonstrated that the use of calcium chloride may be an alternative to try to transform a VF in an asystole, with the possibility of using electric defibrillator in patients unresponsive to epinephrine alone.