膝關節置換手術時可在關節周圍注射止痛劑作疼痛控制


  Feb. 28, 2005(華盛頓) - 一項發表於美國骨科醫師學會第72屆年會中的盲性、隨機性研究結果顯示,在膝關節置換手術完成前,於關節處注射止痛劑,可以明顯的降低疼痛的程度,而且效果可以維持至手術後24小時。
  
  來自澳洲雪梨的Lawrence Kohan醫師表示,若使用經過過濾的血液再灌注,以減少或避免輸血的需要,那這項注射法就不合適了;因為該項局部止痛注射劑中,有一藥物ropivacaine,可能會導致心臟短暫停止;目前估計,約有20%的外科醫師會使用這樣的再灌注方式。
  
  加拿大倫敦保健醫學中心的Ben Shore醫師負責研究的進行,他將64位患者以隨機的方式投予止痛劑處方;該處方的成分為30mg 的ketorolac、5mg 的epimorphine、0.6mL的 0.1% epinephrine及400mg 的ropivacaine,一共100mL的容量;在手術接近終了時,將這些止痛劑分別於三個部位作局部注射;研究人員以盲性的方式,對接受注射者(試驗組)及未接受注射者進行評估。
  
  所有的患者都接受標準止痛程序,在術後24小時,患者皆可以以自行控制的方式作疼痛控制;試驗組的患者,第一小時的嗎啡使用量降低了50%,四個小時以後進行問卷調查後發現,試驗組的滿意度明顯較高,該組的疼痛程度,在第4至第24小時內,也明顯較低;兩組在併發症方面並沒有明顯差異,外傷的併發症狀況也類似;試驗組中,並沒有發現心臟或中樞神經方面的毒性。
  
  在術後24小時,兩組在許多項目上,並未顯示明顯差異;這些項目,含疼痛程度、住院期,及膝部的活動範圍等;Shore醫師表示,這是合理的,因為ropivacaine的半衰期為18小時。
  
  該項技術的研發者之一Kohan醫師表示,由膝蓋出來的ropivacaine濃度很高,因此再灌注是很危險的;除此之外,Kohan醫師對此技術表示支持,他進一步表示,我們不能再以隨機的方式進行試驗,因為試驗組的效果實在是太好了。
  
  Kohan醫師再度表示,疼痛控制在膝關節置換手術中,是很重要的一環,因為這項手術是用來增進患者的生活品質,而疼痛及嗎啡都會導致活動不良及較長的住院期,也會引發致命的併發症,如肺阻塞就是一例。
  
  Shore醫師指出,院內的所有醫師,已經因為這項研究而採用了關節周圍注射法,來作為膝關節置換手術的一環,但是研究進行之前,這個方法並未被持續性的採用。

Peri-articular Analgesia Injec

By Karla Harby
Medscape Medical News

Feb. 28, 2005 (Washington) — Injecting the knee with local analgesia near the end of a total knee replacement results in significantly less pain for up to 24 hours after the procedure, according to the results of a blinded, randomized trial described here at the 72nd annual meeting of the American Academy of Orthopaedic Surgeons.

The injections are not suitable, however, for surgeons who use filtered blood reinfusion drains to minimize or avoid blood transfusions during surgery. One of the local analgesics used, ropivacaine, can stop the heart, albeit reversibly, commented Lawrence Kohan, MD, director of the Joint Orthopaedic Centre, Sydney, Australia. He estimated that about 20% of surgeons use such reinfusions.

Ben Shore, MD, staff orthopaedic surgeon at the London Health Sciences Centre in Ontario, Canada, and colleagues randomized 64 patients to receive a cocktail of analgesics. The cocktail consisted of 30 mg of ketorolac, 5 mg of epimorphine, 0.6 mL of 0.1% epinephrine, and 400 mg of ropivacaine, in a 100 mL volume. This was injected at three local sites toward the end of the procedure. The investigators who evaluated the results were blinded regarding which patients received injections and which did not.

All patients received access to patient-controlled analgesia for 24 hours postsurgery, followed by standard analgesia thereafter. Patients who received the injections showed a nearly 50% reduction in their use of morphine during the first 24 hours (P = .013). Patient satisfaction at four hours postsurgery, as measured by questionnaire, was also significantly greater in the injected analgesia group (P = .003), and measures of pain during activity at four hours and 24 hours using the visual analog scale were significantly less (P = .001). There were no differences in complications, including wound complications, between the two groups. The investigators also found no evidence of cardiac or central nervous system toxicity from the analgesic cocktail.

The investigators did not observe any statistically significant differences between the two groups after 24 hours, however. This included measures of pain as well as length of hospital stay and the range of motion of the knee joint. "This makes sense, because the half-life of ropivacaine is 18 hours," Dr. Shore said.

Dr. Kohan, who is known as a developer of this technique, said in an interview that ropivacaine comes out of the knee in high concentrations and is therefore dangerous to reinfuse. But otherwise he is a strong proponent, and praised Dr. Shore's group for doing this study. "We can't do a randomized study anymore, ethically, because the results are so much better for the patients in the injected group," he said.

Dr. Kohan pointed out that pain control is vital in total knee replacement — an elective procedure designed to improve quality of life for healthy people — because pain and morphine can lead to inactivity and prolonged hospital stays. These in turn can lead to life-threatening complications, such as pulmonary embolism.

Dr. Shore said his study has caused all surgeons at his institution to adopt routine use of peri-articular injections in total knee replacements. "It wasn't used consistently before this study," he told Medscape.

The researchers disclosed no conflicts of interest.

AAOS 72nd Annual Meeting: Abstract 421. Presented Feb. 27, 2005.

Reviewed by Gary D. Vogin, MD

    
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