Question:
In patients having hip or knee replacement, what is the relative efficacy of regional and general anesthesia?
Data sources:
Studies were identified in MEDLINE (1966 to April 2008), EMBASE/Excerpta Medica (1969 to April 2008), and the Cochrane Library. Reference lists of relevant articles were reviewed, and authors were asked if they knew of any other relevant published studies.
Study selection and assessment:
Studies were included if they were randomized controlled trials (RCTs), published in English, and compared regional anesthesia with general anesthesia in patients having elective total hip or knee replacement.
Main outcome measures:
Outcomes of interest were operating time, intraoperative blood loss, requirement for blood transfusion, incidence of deep venous thrombosis or pulmonary embolism, postoperative nausea and vomiting, length of hospital stay, and death.
Main results:
21 RCTs met the inclusion criteria. A random effects model was used to calculate effect sizes among pooled trials. Meta-analysis showed better results were associated with regional anesthesia for operating time (total hip replacement), intraoperative blood loss (total hip replacement), transfusion requirement (total hip replacement), deep venous thrombosis, and postoperative nausea and vomiting (Table). No significant difference between regional and general anesthesia was found with regard to the incidence of pulmonary embolism, length of hospital stay, or death (Table).
Conclusion:
In patients having hip or knee replacement, regional anesthesia is associated with reductions in the duration of surgery, intraoperative blood loss, need for transfusion, postoperative nausea and vomiting, and incidence of deep venous thrombosis compared with general anesthesia.
Epidural anesthesia and spinal regional anesthesia are the prevalent methods used in high-volume hip and knee replacement centers. Two caveats are important in judging this meta-analysis. First, the 21 articles reviewed did not include all data points reviewed, i.e., data for nausea and vomiting were present in only two studies. Second, data for hematologic results and surgical duration were valid only for total hip replacement, as those measures were confounded by the use of a tourniquet in patients receiving a total knee replacement.
The equality of surgical duration with total knee replacement strongly suggests that the decreased duration with total hip replacement is due to decreased blood loss. Intraoperative blood loss was decreased with regional anesthesia when combined with anesthetic hypotension, which is now the routine method of regional anesthesia. Also, postoperative hemoglobin levels are a better measure because intraoperative blood loss is rarely accurately measured.
While there was no difference with regard to pulmonary embolism when chemoprophylaxis was used, both deep venous thrombosis and pulmonary embolism were significantly decreased (p = 0.0001) with regional anesthesia with no drugs. This confirms the prior research that regional anesthesia reduces blood clots1. This benefit may be related in total hip replacement to the reduced surgery time and greater intraoperative volume replacement, which better maintains hemodynamic equilibrium. With the current practice of pain management, in which narcotics are avoided and antiemetics are used2, nausea should be reduced with either method of anesthesia. In conclusion, the greatest benefit of regional anesthesia for total hip replacement is the hematologic and hemodynamic improvement, which cannot be judged in total knee replacement because of tourniquet use.
References
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GH;
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TP. The incidence of venous thromboembolism after total hip arthroplasty: a specific hypotensive epidural anesthesia protocol. J Arthroplasty.
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Maheshwari
AV;
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LD. Multimodal analgesia without routine parenteral narcotics for total hip arthroplasty. Clin Orthop Relat Res.
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