Comparison of ketamine-pentobarbital anesthesia and fentanyl-pentobarbital anesthesia for open-heart surgery in minipigs

The effects of pentobarbital, ketamine–pentobarbital and ketamine–xylazine anesthesia in a rat myocardial ischemic reperfusion injury model

To achieve reliable experimental data, the side-effects of anesthetics should be eliminated. Since anesthetics exert a variety of effects on hemodynamic data and incidence of arrhythmias, the selection of anesthetic agents in a myocardial ischemic reperfusion injury model is very important. The present study was performed to compare hemodynamic variables, the incidence of ventricular arrhythmias, and infarct size during 30 min of ischemia and 120 min of reperfusion in rats using pentobarbital, ketamine–pentobarbital or ketamine–xylazine anaesthesia. A total of 30 rats were randomly divided into three groups. In group P, pentobarbital (60 mg/kg, intraperitoneally [IP]) was used solely; in group K–P, ketamine and pentobarbital (50 and 30 mg/kg, respectively, IP) were used in combination; and in group K–X, ketamine and xylazine (75 and 5 mg/kg, respectively, IP) were also used in combination. Hemodynamic data and occurrence of ventricular arrhythmias were recorded throughout the experiments. The ischemic area was measured by triphenyltetrazolium chloride staining. The combination of ketamine–xylazine caused bradycardia and hypotension. The greatest reduction in mean arterial blood pressure during ischemia was in the P group. The most stability in hemodynamic parameters during ischemia and reperfusion was in the K–P group. The infarct size was significantly less in the K–X group. Whereas none of the rats anesthetized with ketamine–xylazine fibrillated during ischemia, ventricular fibrillation occurred in 57% of the animals anesthetized with pentobarbital or ketamine–pentobarbital. Because it offers the most stable hemodynamic parameters, it is concluded that the ketamine–pentobarbital anesthesia combination is the best anesthesia in a rat ischemia reperfusion injury model.

Hippocampal long-term potentiation in adult mice after recovery from ketamine anesthesia

Ketamine is frequently used to induce analgesia or anesthesia in laboratory animals, but its effects on learning and memory are poorly characterized. Long-term potentiation (LTP) is considered a cellular mechanism for learning and memory. Ketamine administration immediately abolishes hippocampal LTP in vivo, but whether this effect persists is not known. The authors administered one of two doses of ketamine to adult male C57BL/6 mice and measured LTP in hippocampal slices from the mice 24 h later. Neither LTP induction nor LTP maintenance differed significantly in mice that were administered ketamine compared with mice that were administered saline. The findings suggest that a single intraperitoneal dose of ketamine does not persistently alter LTP in adult male mice.

The efficacy of terlipressin versus adrenaline in swine cardiopulmonary resuscitation

BACKGROUND AND OBJECTIVES

The objective of the present study was to evaluate the efficacy of terlipressin (TP) vs. adrenaline (ADR) in increasing coronary perfusion pressure (CPP) and return of spontaneous circulation (ROSC) in swine CPR.

METHODS

Under anesthesia with ketamine/thiopental, ventricular fibrillation was induced in 44 female immature pigs, remaining unassisted for 10 minutes, followed by 2 minutes of manual CPR (100 compression/10 ventilations/min with air). Animals were, then, divided into four groups: 1) ADR (45μg.kg(-1)); 2) saline-placebo (10mL); 3) TP 20μg.kg(-1)); and TP (20μg.kg(-1)) + ADR (45μg.kg(-1)). Defibrillation was performed after 2 minutes, observing surviving animals for a 30-minute period. Electrocardiogram, systemic BP, DBP, and PetCO(2) were monitored continuously.

RESULTS

Terlipressin did not differ from placebo regarding the effects on CPP, with low rates of ROSC in both groups (1/11 vs. 2/11; p=NS). Adrenaline increased CPP from 13±12 to 54±15mmHg (p<0.0001), similar effect to TP + ADR (from 21±10 to 45±13mmHg; p<0.0001), with high rates of ROSC/survivors in both groups (10/11 vs. 9/11, respectively). Among survivors, greater MAP was observed in the TP + ADR group vs. ADR (105±19mmHg vs. 76±21mmHg; p=0.0157) groups.

CONCLUSIONS

Adrenaline and TP + ADR were effective on maintaining CPP/ROSC in this experimental model, but isolated TP did not differ from placebo. However, in surviving animals in the TP + ADR group, greater hemodynamic stability was observed after ROSC, suggesting that TP can be a useful medication in the management of post-CPR hypotension.