BACKGROUND:In 1990s,overseas researchers use balloon occlusion method for establishing closed-chest animal models of myocardial infarction. But,ventricular fibrillation and thrombosis of intraoperative factors reduce the success rate of establishing the models. Currently,there are a few reports on establishing the large animal models. OBJECTIVE:We used balloon occlusion method for establishing closed-chest swine models of myocardial infarction,and explored ways to improve the success rate of modeling. DESIGN,TIME AND SETTING:The randomized controlled animal study of pathology observation was performed at the Department of Cardiology,First Affiliated Hospital of Kunming Medical College and Research Room of Pathology,Kunming Medical College from July 2008 to May 2009. MATERIALS:Fifteen Diannan small-ear pigs weighing 19-25 kg,aged 8-11 months,were divided into three groups:sham operation group,ischemia-reperfusion group,and ischemic postconditioning group,with 5 pigs in each group.METHODS:After the coronary occlusion and reperfusion period,the prophylactic use of lidocaine (1.0-2.0 mg/kg) infusion to control arrhythmia,and use of heparin to prevent and treat the thrombosis. A balloon catheter was positioned in the distal end of the first diagonal branch of the left anterior descending (LAD) artery under fluoroscopic guidance. In the sham operation group,the balloon was only placed to the LAD,did not block coronary artery. In the ischemia-reperfusion group,inflatable balloon occlusion was done for 60 minutes in the LAD after the balloon removed. In ischemic postconditioning group,after the balloon was inflated and occluded the LAD for 60 minutes,ischemic postconditioning was elicited by eight cycles of 30-second reperfusion,followed by 30-second reocclusion.MAIN OUTCOME MEASURES:Coronary angiography,electrocardiogram (ECG) and cardiac enzymes test was conducted to evaluate models of myocardial infarction. After three days,cardiac 2,3,5-triphenyltetrazolium chloride (TTC) staining and pathological examination was done to verily myocardial infarction.RESULTS:In the sham operation group,all pigs survived. In the ischemia-reperfusion group,4 pig models of myocardial infarction were successfully established,and one died of refractory ventricular fibrillation. In the ischemic postconditioning group,models of myocardial infarction after ischemia were successfully established. Following distal left anterior descending artery occlusion,the ECG leads V13 on the ST-segment elevation,the sick rational Q-wave formed;myocardial enzyme evolution of myocardial infarction in the human body was basically the same process. The site of myocardial infarction,basically the same parts,was located in apical,left ventricular anterior wall,and the former interval. TTC staining was normal myocardium brick red,myocardial infarct area appeared pale;pathological examination revealed a normal structure of myocardial infarct damage,cytoplasm condensed,dyeing deepening,transverse striations disappeared,nuclear enrichment,dissolution,fragmentation,many erythrocytes around the infarct area with abundant granulation tissue and a large infiltration of inflammatory cells.CONCLUSION:The described model presents a less invasion to the animals,and is the closest to the process of clinical practice.Intraoperative use of lidocaine and heparin for controlling arrhythmia and thrombosis of the models is successfully established as an effective manner. Ischemic postconditioning may be one of the factors for improving the modeling success rate.

Objective To evaluate the feasibility of induction with sevoflurane-midazolam-remifentail for tracheal intubation without muscle relaxants in neck brake patients.Methods Forty ASA Ⅰ or Ⅱ patients with cervical spine fracture with dislocation,aged 13-68 yr,scheduled for surgery under general anesthesia,were enrolled in this study.Anesthesia was induced with iv injection of midazolam 0.03 mg/kg and inhalation of 5%sevoflurane through a mask.Sevoflurane was inhaled at the initial concentration of 5%,followed by decrement of 1% every 30 s until 3%.When the eyelash reflex disappeared,remifentanil 2 μg/kg was injected slowly over 45s and 30 s later sevoflurane inhalation was stopped.The patients were mechanically ventilated after tracheal intubation.The time of disappearance of eyelash reflex was recorded.The intubation condition was evaluated using VibyMogensen score.Results All patients were successfully intubated at the first attempt.The time period from sevoflurane inhalation to disappearance of eyslash reflex was(69 ± 4)s.Coughing occurred in 3 cases during intubation.The satisfactory intubation conditions were found in 100% of cases.SpO2 ＞ 95% in all patients.BlS was maintained at 45-55 during the period(before intubation until 3 min after intubation).Conclusion Induction with sevoflurane-midazolam-remifentail is rapid and smooth,provides good conditions for intubation and can be applied to tracheal intubation without muscle relaxants in neck brake patients.