Efficacy of thoracic paravertebral block for preemptive analgesia in patients undergoing minimally invasive direct coronary artery bypass grafting / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the efficacy of thoracic paravertebral block for preemptive analgesia in the patients undergoing minimally invasive direct coronary artery bypass grafting (MIDCAB).Methods Sixty patients of both sexes,aged 54-75 yr,weighing 55-82 kg,of American Society of Anesthesiologists physical Ⅱ or Ⅲ,with New York Heart Association Ⅰ-Ⅲ,scheduled for elective MIDCAB,were randomly divided into 2 groups (n =30 each) by using a random number tablecontrol group (group C) and thoracic paravertebral block group (group P).Thoracic paravertebral block was performed under the guidance of a nerve stimulator in group P.A paravertebral catheter was placed at T4,5 interspace,a test dose of 0.5％ ropivacacine 5 ml was injected through the catheter,and 5 min later a bolus dose of 0.5％ ropivacacine 15 ml was injected.Anesthesia was induced with intravenous etomidate,midazolam,fentanyl and vecuronium.All the patients were intubated with a double-lumen endobronchial tube and mechanically ventilated,and end-tidal pressure of carbon dioxide was maintained at 30-40 mmHg.Anesthesia was maintained with intravenous injection of fentanyl and vecuronium,intravenous infusion of propofol,and inhalation of sevoflurane.Bispectral index value was maintained at 40-60.When systolic blood pressure ＞ 160 mmHg,fentanyl 0.1 mg was injected intravenously.Both groups started to receive patient-controlled intravenous analgesia (PCIA) after extubation until 48 h after operation.PCIA solution contained morphine in 100 ml of normal saline.The PCIA pump was set up with a 2 mg bolus dose,a 10 min lockout interval and background infusion at a rate of 0.5 mg/h.Visual analogue scale was maintained ≤ 4.When visual analogue scale＞4,morphine 4 mg was injected intravenously as rescue analgesic.The consumption of intraoperative fentanyl was recorded.The consumption of morphine and requirement for rescue analgesics were recorded within 24 and 48 h after operation.The adverse reactions such as somnolence,nausea and vomiting,respiratory depression,pruritus,and atelectasis were recorded within 48 h after operation.The extubation time after operation,length of time in intensive care unit,and recovery time after operation were recorded.At 24 and 48 h after operation,pulmonary function was detected,the forced vital capacity (FVC) expressed as a percentage of the predicted value (FVC％),and forced expiratory volume in 1 second (FEV1)expressed as a percentage of the predicted value (FEV1 ％) were recorded,and the ratio of FEV1/FVC was calculated.Blood gas analysis was performed,and arterial oxygen partial pressure and partial pressure of arterial carbon dioxide were recorded at 24 and 48 h after operation.Results Compared with group C,the intraoperative consumption of fentanyl and consumption of morphine within 24 and 48 h after operation were significantly reduced,the extubation time and length of time in intensive care unit were shortened,FVC％ and FEV1％ were increased at 24 and 48 h after operation,the partial pressure of arterial carbon dioxide and incidence of somnolence were decreased (P＜0.05),and no significant change was found in the FEV1 / FVC,arterial oxygen partial pressure,requirement for rescue analgesics and recovery time after operation in group P (P＞0.05).Conclusion Thoracic paravertebral block analgesia can provide good preempive analgesia in the patients undergoing MIDCAB.