The use of mice and rats as animal models for cardiopulmonary resuscitation research

Abstract

Cardiopulmonary resuscitation (CPR) after the induction of cardiac arrest (CA) has been studied in mice and rats. The anatomical and physiological parameters of the cardiopulmonary system of these two species have been defined during experimental studies and are comparable with those of humans. Moreover, these animal models are more ethical to establish and are easier to manipulate, when compared with larger experimental animals. Accordingly, the effects of successful CPR on the function of vital organs, such as the brain, have been investigated because damage to these vital organs is of concern in CA survivors. Furthermore, the efficacy of several drugs, such as adrenaline (epinephrine), vasopressin and nitroglycerin, has been evaluated for use in CA in these small animal models. The purpose of these studies is not only to increase the rate of survival of CA victims, but also to improve their quality of life by reducing damage to their vital organs after CA and during CPR.

How Can we Study Cardiopulmonary Resuscitation and Cardiac Arrest in Animals: a Review

“…On the one hand, rodents present two different cranial venae cavae (right and left) with a coronary sinus formed by the proximal part of the left cranial vena cava [6]. This directly modifies the coronary perfusion during cardiac massage through different venous return as compared to large animals [7]. In addition, due to their very low body mass, cardiac massage could make blood circulating through direct heart compression, while it is mostly acting through thoracic pumping in large animals.…”

“…In addition, due to their very low body mass, cardiac massage could make blood circulating through direct heart compression, while it is mostly acting through thoracic pumping in large animals. On the other hand, spontaneous heart rate is much higher in rodents than in large animals and humans as usual values average 260-450 or 500-600 beats per minute in awake rats and mice, respectively [7,8]. This directly impacts the required chest compression rate in those species as mice should undergo ≈400 compressions per min to be resuscitated [9][10][11][12][13][14].…”

“…Subsequently, ventricular fibrillation (VF) is able to Volume 3 Issue 2 -2016 convert spontaneously in these species, i.e., within the first 1-2 min following VF induction. Experimentally, prolonged electrical stimulation should be delivered to obtain sustained VF in these species [7]. Therefore, rodents are mostly used for exploratory and mechanistic studies.…”

“…For example, if the current is delivered outside the vulnerable period or if the magnitude exceeds the limits of vulnerability, VF cannot be obtained [35]. In small animals, this method could not be implemented as VF could convert spontaneously after a short stimulus [7]. Shockable cardiac arrest could also be induced with less powerful current through endocavitary electrodes.…”

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“…6 This directly modifies the coronary perfusion during cardiac massage through different venous return as compared to large animals. 7 In addition, due to their very low body mass, cardiac massage could make blood circulating through direct heart compression, while it is mostly acting through thoracic pumping in large animals. On the other hand, spontaneous heart rate is much higher in rodents than in large animals and humans as usual values average 260-450 or 500-600 beats per minute in awake rats and mice, respectively.…”