手術前使用會陰神經阻斷麻醉並無額外助益


  Sept. 20, 2005(亞特蘭大)- 根據一項可預期的隨機試驗發現,在陰道骨盆重建手術前,先進行會陰神經阻斷麻醉,並不會降低手術後疼痛的強度,或可減少無痛麻醉劑之使用量。
  
  來自伊利諾州西北大學伊凡斯頓芬得醫學院婦科泌尿學系的Yoram Abramov醫學博士向Medscape表示,隨著陰道重建手術後來的疼痛感,一般是來自陰戶後面部分,會陰,刺狀薦骨韌帶區以及骨盆底部;會陰神經阻斷麻醉施用在刺狀薦骨韌帶,可提供這些區域相當有效的麻醉效果。
  
  從一些病患在經其他種類之手術後的小型臨床研究結果顯示,建議術前會陰神經阻斷麻醉可能降低手術後之疼痛感;美國泌尿產科學會第26屆年會上,Abramov博士指出,目前為止,並無相關研究報導刊載有關陰道重建手術前使用麻醉劑之文獻。
  
  這項試驗包括106名在2001年11月至2004年12月間接受一般麻醉劑下進行陰道骨盆重建手術之病患,病患年齡在20-80歲間,為美國麻醉學者學會(ASA)第一級及第二級狀態;慢性病以及/或使用麻醉藥習慣,精神方面疾病,以及無法接受嗎啡或局部麻醉劑者,皆會被排除在試驗之外。
  
  一般靜脈注入之麻醉劑由fentanyl 2 μg/kg, propofol 2 mg/kg, atracurium 0.5 mg/kg組成,須將氮氧含量維持在70%,isoflurane維持在0.5%至1.0%間;會陰神經阻斷麻醉由10 cc bupivacaine 0.25% (n = 53) 或 saline (n = 53)組成,手術前立即從兩邊注入;若手術持續超過2小時,每邊會再額外注入5 cc;手術過後,所有病患將由靜脈施打經管制之hydromorphone強效麻醉劑,藥效持續18小時。
  
  不同治療群組的基本病徵,治療過程中之併發症比率,以及一般麻醉數量等,皆無顯著不同;106名隨機抽樣之病患中,有102名的資料可供分析研究;手術後觀察1至24小時,在疼痛指數記錄中發現,各群組的疼痛指數並無顯著不同;同樣地,在手術後,hydromorphone強效麻醉劑之使用量,不同群組間是相似的(bupivacaine組別之使用量為5.92 ± 3.91 mg,saline組別之使用量為5.32 ± 2.48 mg [P = .39])。
  
  根據Abramov博士的說法,在陰道骨盆重建手術時,先進行會陰神經阻斷麻醉,對於疼痛強度方面的助益不大,可能歸因於陰道骨盆手術所產生的疼痛是有限的,預先麻醉期間較短;至於其效果可能被過量之管制性麻醉藥給掩蓋過的說法,Abramov博士表示不太可能。
  
  Abramov博士認為,這項研究是僅能偵測到20%以上較大的差異;因此,少數之差異發生時可能已被忽略。
  
  Abramov總結指出,雖然會陰神經阻斷麻醉已被相當安全的使用在陰道骨盆重建手術,但於任何種類之陰道骨盆重建手術時,目前並無研究正面肯定在手術前使用這類麻醉藥,潛在的負面因素包括於靜脈局部注射麻醉劑之副作用,如心律不整等。

Preemptive Pudendal Nerve Bloc

By Emma Hitt, PhD
Medscape Medical News

Sept. 20, 2005 (Atlanta) — Pudendal nerve blockade administered prior to transvaginal pelvic reconstructive surgery does not diminish postoperative pain intensity or the consumption of narcotic analgesia, according to the findings of a prospective, randomized trial.

"Postoperative pain following vaginal reconstruction is commonly localized to the posterior vulva, the perineum, the region of the sacrospinous ligament, and the pelvic floor," Yoram Abramov, MD, from the Division of Urogynecology at the Northwestern University, Feinberg School of Medicine in Evanston, Illinois, told Medscape. "Pudendal nerve blockade is administered at the sacrospinous ligament and provides highly effective anesthesia to these areas."

Results from smaller clinical studies in patients undergoing other types of surgery have suggested that preemptive pudendal nerve blockade may reduce postoperative pain. Speaking here at the 26th annual meeting of the American Urogynecologic Society, Dr. Abramov noted that no studies have been published on preemptive analgesia for pelvic reconstructive surgery.

The trial included 106 patients undergoing transvaginal pelvic reconstructive surgery under general anesthesia between November 2001 and December 2004. Patients were aged 20 to 80 years and American Society of Anesthesiologists (ASA) status I or II. Exclusion criteria included chronic pain and/or narcotic consumption, psychiatric disease, and intolerance to morphine or local anesthetics.

General anesthesia consisted of induction intravenous fentanyl 2 µg/kg, propofol 2 mg/kg, atracurium 0.5 mg/kg, and maintenance nitrous oxide 70% and isoflurane 0.5% to 1.0%. Pudendal block analgesia consisted of 10 cc of either bupivacaine 0.25% (n = 53) or saline (n = 53) both given bilaterally immediately before surgery. An additional 5 cc were injected to each side if the surgery lasted more than two hours. Postoperatively, all patients received patient-controlled intravenous hydromorphone for 18 hours.

Baseline characteristics, rate of concomitant procedures, and amount of general anesthesia were not significantly different between treatment groups. Of the 106 randomized patients, 102 were included in the analysis. Pain scores were recorded from one hour to 24 hours postoperatively and were not significantly different between groups. Likewise, postoperative hydromorphone consumption was similar (5.92 ± 3.91 mg in the bupivacaine group and 5.32 ± 2.48 mg in the saline group [P = .39]).

According to Dr. Abramov, possible explanations for the lack of benefit include the limited pain intensity with transvaginal pelvic surgery; the short duration of preemptive analgesia (no boluses were given postoperatively); and the chance that the effect was masked by patient-controlled analgesia overdose, which he said was unlikely.

Dr. Abramov noted that the study was "powered to detect only a 20% or greater difference, therefore, the occurrence of a smaller difference may have been overlooked.

"Although pudendal nerve blockade has been employed safely during pelvic reconstructive surgery, at present, there is no evidence to support the use of this type of preemptive analgesia for any type of pelvic reconstructive surgery," Dr. Abramov concluded. "Potential disadvantages include side effects associated with intravenous injection of local anesthetics, including cardiac arrhythmia."

AUGS 26th Annual Scientific Meeting: Paper 21. Presented Sept. 16, 2005.

Reviewed by Gary D. Vogin, MD

    



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