Asphyxial Circulatory Arrest with a Complex of Resuscitation Measures in an Experimental Model

Abstract

The majority of asphyxial circulatory arrest (CA) models have a number of disadvantages, such as the lack of uniform criteria for fixing CA and recovery of spontaneous circulation, short duration of CA episode and limited volume of post-resuscitation intensive care, poor similarity with resuscitation measures in current clinical anesthesiology/intensive care settings.The aim of the study: to improve the experimental model of asphyxicial CA by standardizing experimental procedures and using a complex of resuscitation measures replicating current CA management in clinical anesthesiology-intensive care.Materials and methods. The experiments were conducted on 34 male Wistar rats, distributed into 2 groups: Group I included animals subjected to sham procedure (SP, N=12) and Group II – animals subjected to asphyxial circulatory arrest (CA, N=22) and subsequent resuscitation. Asphyxia in anesthetized rats was induced by rocuronium bromide injection, followed by recording of electrocardiogram (ECG), parameters of invasive blood pressure (BP) measurement and laser Doppler fluxmetry (LDF) to assess skin perfusion. CA episode was maintained for 2 min, followed by a series of resuscitation measures and intensive therapy for 2 h. Circulatory parameters (ECG, BP, LDF), gas composition and arterial blood acid-base state (ABS) dynamics were evaluated.Results. Monitored parameters were comparable in both groups at baseline after stabilization period. After exclusion criteria were applied 11 animals from SP group and 18 — from CA were included in the analysis. Tachycardia (heart rate, beats/min–1, SP vs CA) was documented in the CA group: 218 [205; 236] vs 286 [272; 305], P⩽0.0001), as well as recovery of skin perfusion to subnormal parameters in the first minutes after successful resuscitation. At minute 10 in the post-resuscitation period worsening of skin perfusion (M, perfusion units, SP vs CA): 14.7 [12.1; 16.5] vs 10.1 [7.0; 12.5], P=0.0014), and decompensated mixed acidosis (pH, SP vs CA): 7.42 [7.40; 7.43] vs 7.20 [7.13; 7.23], P⩽0.0001) were documented in the CA group, however BP values were comparable (BP, mmHg, SP vs CA): 60 [58; 72] vs 67 [62; 82], P=0.482). At minute 120 post-resuscitation and at the end of intensive care period, both groups demonstrated similar values of the monitored parameters. Three out of 18 animals in the CA group died after resuscitation.Conclusion. Electromechanical dissociation underlies CA in rats subjected to asphyxia. The use of LDF to assess peripheral blood flow makes it possible to standardize the severity of ischemic reperfusion injuries and improve reproducibility of the model. Series of resuscitation measures in experimental setting is justified from a bioethical point of view, and makes it possible to improve repeatability of preclinical research results in clinical practice.

Keywords

• circulatory arrest
• asphyxia
• resuscitation measures
• experimental model
• rat