Independent risk factors for postoperative shivering.

Postoperative shivering (PAS) is uncomfortable for patients and potentially risky. In this observational trial we sought to identify independent risk factors for PAS after general anesthesia. Potential risk factors for PAS were recorded in 1340 consecutive patients. Signs of shivering, peripheral and core temperature, and thermal comfort were recorded in the postanesthetic care unit. The data were split into an evaluation data set (n = 1000) and a validation data set (n = 340). The first was used to identify independent risk factors for PAS and to formulate a risk score using backward-elimination logistic regression analysis. The proposed model was subsequently tested for its discrimination and calibration properties using receiver operating characteristic (ROC)-curve analysis and linear correlation between the predicted and the actual incidences of PAS in the validation group. The incidence of PAS was 11.6%. There were three major risk factors: young age, endoprosthetic surgery, and core hypothermia, with age being the most important. The risk score derived from this analysis had a reasonable discriminating power, with an area under the ROC-curve of 0.69 (95% confidence interval, 0.60-0.78; P < 0.0001). Furthermore the equation of the calibration curve (y = 0.69x + 6; R2= 0.82; P < 0.05) indicated a good and statistically significant agreement between predicted and actual PAS incidence. Postoperative shivering can be predicted with acceptable accuracy using the four risk factors identified in the present study. The presented model may serve as a clinical tool to help clinicians to rationally administer prophylactic antishivering drugs.

Postoperative analgesia and functional recovery after total-knee replacement: comparison of a continuous posterior lumbar plexus (psoas compartment) block, a continuous femoral nerve block, and the combination of a continuous femoral and sciatic nerve block.

BACKGROUND AND OBJECTIVES: Continuous femoral nerve block is a well-accepted technique for regional analgesia after total-knee replacement. However, many patients still experience considerable pain at the popliteal space and at the medial aspect of the knee. The goal of this study is to evaluate whether a psoas compartment catheter provides better postoperative analgesia than a femoral nerve catheter does and whether it is as effective as the combination of a femoral and a sciatic nerve catheter and, thus, improves functional outcome. METHODS: Ninety patients who underwent total-knee replacement under standardized general anesthesia participated in this prospective randomized study. Group FEM received a continuous femoral nerve block, group FEM/SCI received a combination of a femoral and a sciatic continuous nerve block, and group PSOAS received a continuous psoas compartment block. Patient-controlled analgesia with piritramide was available for 48 hours. Maximal bending and extending of the knee and walking distance was assessed during the first 7 days. A standardized telephone survey was conducted after 9 to 12 months to evaluate residual pain and functional outcome. RESULTS: Postoperative opioid consumption during 48 hours was significantly less in the FEM/SCI group (median: 18 mg; 25th/75th percentile: 6/40) compared with the FEM group (49 mg; 25/66) and the PSOAS group (44 mg; 30/62) (P =.002). Postoperative pain scores were not different, and no differences occurred with respect to short-term or long-term functional outcome. CONCLUSION: The FEM/SCI catheter is superior to FEM and PSOAS catheter with respect to reduced analgesic requirements after total-knee replacement, but functional outcome does not differ with those 3 continuous regional analgesia techniques.