|Budget Amount *help
¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 2000 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
[Introduction] Pretreatment with adenosine prior to regional myocardial ischemia provides myocardial protection against ischemia-reperfusion injury. It is not known, however, whether pretreatment with adenosine prior to cardiac arrest, which causes global myocardial ischemia, exerts such cardioprotective effects. We investigated the effects of adenosine pretreatment on survival following cardiac arrest and resuscitation.
[Methods] Nineteen rabbits weighing approximately 3kg were anesthetized with intramuscular ketamine 35mg/ks and xylazine 5mg/kg. The ear vein was cannulated as a venous access. The ear artery was cannulated for blood pressure monitoring and blood sampling. A 4mm pediatric tracheatube was inserted via tracheotomy. Thereafter animals were anesthetized with 1% isoflurane in oxygen-enriched air (FiO2=0.5) and paralyzed with vecuronium. Ventilation was controlled to maintain end-tidal CO2 tension between 30 and 40 torr. Via mini-sternotomy an electromagnetic flow probe, a pl
astic catheter and a Millar catheter were placed on the ascending aorta, into the left atrium and into the left ventricle, respectively. Following operative procedures, repeated measurements of hemodynamic parameters including cardiac output and arterial pressure were started. After baseline measurements, animals were divided into 2 groups ; Group A (n=10) and Group C (n=9) received infusions of adenosine in saline (50ms/kg over 30min) and saline alone, respectively. After the infusion, ventricular fibrillation (Vf) was induced with a fibrillator. The fibrilator was removed after 2 minutes of Vf. If beating of the heart did not resume spontaneously within 30 seconds, electrical defibrillation was applied. When cardiac output remained higher than 60% of the baseline 30 minutes after defibrillation, the animal was classified as "successfully resuscitated".
[Results and Discussion] Seven out of 10 animals in Group A and only 1 out of 9 animals in Group C were successfully resuscitated (p<0.05). They and survived for another 60 minutes Pretreatment with adenosine infusion thus significantly increased the chance of "successful resuscitation".
Although one report has suggested that adenosine infusion during cardiac arrest may not improve resuscitation rate, our data indicates that adenosine infusion prior to global myocardial ischemia improves resuscitation and survival rates significantly.