Effects of interposed abdominal aorta compression for cardiopulmonary cerebral resuscitation on cardiac arrest in rabbit models

Abstract

Objective To determine the effects of interposed abdominal aorta compression as a novel approach on cardiopulmonary resuscitation (CPR) in rabbits with cardiac arrest (CA).Methods Twentyeight healthy New Zealand rabbits with 2.0-2.5 kg body weight were randomly (random number) divided into two groups in equal number (n =14).And they were resuscitated either by external chest compression CPR (CC-CPR) or by interposed abdominal aorta compression for cardiopulmonary resuscitation (IAAC-CPR),in which the abdominal aorta was compressed intermittently at the same rate of external chest compression.The model of CA was made by injection of iced potassium chloride combined with occlusion of trachea.Electrocardiogram (ECG),hemodynamic variables including mean arterial pressure (MAP),aorta systolic blood pressure (SBP),and cerebral blood flow (CBF) were monitored continuously from 5 minutes before cardiac arrest to the end of experiment.MAP,SBP and CBF were calculated and compared at 30 s,60 s,90 s and 120 s of resuscitation between both groups.Blood samples were taken before modeling,and 2 h and 6h after the restoration of spontaneous circulation (ROSC).The rate of ROSC and successful resuscitation,24-hour survival rate,24-hour neurological deficit score and changes of S100B in serum were recorded and compared.The ultramicro-structures of myocardium,lung and brain tissues were observed with HE staining.The data were analyzed by using t-test or Fisher's exact probability test.Results Compared with CC-CPR,the MAP (mmHg),SBP and CBF values in the IAAC-CPR group were significantly increased within 2 minutes of resuscitation,MAP:[30 s:(46.4 ± 9.4) vs.(31.4 ± 8.7,60) s:(55.8±13.8) vs.(34.0±11.5); 90s:(61.2±11.5) vs.(38.2±10.1); 120s:(63.6±11.8)vs.(40.2±10.2); 95％CI,30 s:-21.73--12.41,60s:-28.03--16.26,90 s:-25.27--14.87,120s:-25.38--13.19; t:30 s:-7.536,60 s:-7.734,90 s:-7.943,120 s:-6.505; P＜0.05,P＜0.01]; SBP (mmHg):[30s:(62.6±9.2) vs.(43.4±15.1); 60s:(75.4±14.0) vs.(50.4±13.8); 90s:(78.4±12.6) vs.(59.4±16.2),120s:(82.8±10.3)vs.(64.3 ±15.9); 95％CI,30 s:-28.91--9.51,60 s:-35.82--14.18,90 s:-30.28--7.71,120s:-28.93--8.07; tvalue:30s:-4.071,60 s:-4.751,90 s:-3.460,120 s:-3.647; Pvalue,30s:P＜0.05,P＜0.01,60 s:P＜0.05,P＜0.01,90s:P=0.02,P＜0.05,120s:P=0.01,P＜0.05]; CBF [30s:(16.1±6.0) vs.(7.8±2.2); 60s:(91.6±11.8) vs.(57.3±23.2); 90s:(259.9±74.9) vs.(163.6±50.3); 120s:(301.5±60.5) vs.(208.4±23.8); 95％CI,30s:-14.82--1.70,60s:-61.24--7.49,90s:-189.45--3.29,120s:-160.12--26.03; t2:30 s:-2.904,60 s:-2.948,90 s:-2.387,120 s:-3.201; Pvalue,30s:P=0.020,P＜0.05,60 s:P=0.018,P＜0.05,90 s:P =0.044,P＜0.05,120 s:P=0.013,P ＜ 0.05].At 2 h and 6 h after ROSC,the level of S100B protein in serum was significantly lower in the IAAC-CPR group [2 h:(148.7 ± 19.9) vs.(176.0 ± 17.5) ; 6 h:(237.7 ± 17.7) vs.(267.0 ±14.8),95％CI,2 h:4.53-50.05,6 h:9.29-49.26; 2 h:t=2.519,6 h:t=3.164; 2 h:P=0.022,P ＜ 0.05,6 h:P =0.007,P ＜ 0.05).Rate of successfully recovery and the 24 h neurological score of IAAC-CPR group were better than the CC-CPR group (Rate of successfully recovery:80％ vs.60％,x2 =5.250 ; P =0.022,P ＜ 0.05 ; 24 h neurological score:(3.3 ± 1.49) vs (4.4 ± 0.94) ; t =2.429; 95％CI,0.18-2.11 ; P =0.024,P ＜0.05).Myocardial damage was found in both groups.The changes of ultramicro-structure in myocardium,lung and brain tissues of CC-CPR group were more extensive than those of IAAC-CPR group.Obvious damage of abdominal organs was not observed.Conclusion Compared with the CC-CPR,the cardiopulmonary cerebral resuscitation with IAAC-CPR is more effective in the incipient stage of cardiopulmonary resuscitation.IAAC-CPR elevates the MAP,SBP and CBF more noticeable and increases the successful rate of resuscitation,decreasing the injuries in CA models of rabbit. Key words: Cardiac arrest; Cardiopulmonary cerebnal resuscitation; Interposed abdominal aorta compression-cardiopulmonary resuscitation; Chest compression-cardiopulmonary resuscitation; Mean arterial pressure; Cerebral blood flow; S100B protein; 24-hour neurological function score