Effects of intravenous propranolol on heat pain sensitivity in healthy men.

BACKGROUND: Clinical studies have shown opioid-sparing effects of ß-adrenergic antagonists perioperatively and ß-blockers are being investigated for chronic musculoskeletal pain. However, the direct analgesic effects of ß-blockers have rarely been examined in healthy humans. METHODS: In a randomized, counter-balanced, double-blind, within-subject crossover design, we tested the effect of the lipophilic ß-blocker propranolol (0.035 mg/kg body weight i.v.) on heat pain sensitivity in 39 healthy males, compared with placebo. To test for peripheral versus central effects, the peripherally acting ß-blocker sotalol was also examined. Experimental stimuli were brief superficial noxious heat stimuli applied to the volar forearm. Non-painful cold stimuli were included to test for specificity. Sedation, mood and anxiety were assessed to investigate potential mechanisms underlying any analgesic effect. ß-blocker effects on blood pressure were incorporated into the analysis because of a known inverse relationship between pain sensitivity and systolic blood pressure. RESULTS: Propranolol significantly decreased perceived intensity of heat pain stimuli but only in participants with small propranolol-induced blood pressure decreases. Even in this group, the effect was small (4%). Propranolol did not influence perceived intensity of non-noxious stimuli and had no effect on sedation, anxiety or mood. Sotalol did not influence heat pain sensitivity. CONCLUSIONS: Propranolol decreased pain sensitivity but its analgesic effects were small and counteracted by blood pressure decreases. The analgesic effects were not mediated by peripheral ß-receptor blockade, sedation, mood or anxiety. The small effect indicates that the utility of ß-blockers for clinical pain must be related to factors that do not play a significant role for experimental pain.

Incidence of postoperative urinary retention (POUR) after joint arthroplasty and management using ultrasound-guided bladder catheterization.

BACKGROUND: Postoperative urinary retention (POUR) following lower limb arthroplasty is a common complication. The aim of this observational study was to establish the incidence of POUR and assess the usefulness of an ultrasonographic nurse-driven protocol, thereby avoiding elective bladder catheterization. METHODS: Two-hundred and eighty six consecutive patients undergoing elective hip and knee arthroplasty were retrospectively studied. None of the patients received elective bladder catheterization. Data on risk factors for POUR, urinary tract infections, length of hospital stay and analgesia were collected. Student's t, Wilcoxon rank-sum, ANOVA and Kruskall-Wallis tests were performed for comparison among two or more groups. Categorical variables were studied using Pearson's χ2 test. Results were considered significant when the P value <0.05. RESULTS: Of the 286 patients studied, 49 (17%) required indwelling catheter for 24-48 h. Patients who had POUR had more risk factors (P<0.05) and had longer hospital stays (P<0.05). When comparing analgesia, continuous peripheral nerve block (CPNB) had the least impact on POUR (15.8%), while epidural analgesia had the greatest impact (48.1%). CONCLUSION: Bladder scanners timely detect POUR following lower joint arthroplasty, making elective bladder catheterization unnecessary.

Urinary retention after total hip and knee arthroplasty.

Postoperative urinary retention (POUR) occurs after lower joint arthroplasty with an incidence between 0% and 75%. This vast range reflects the differences in diagnosis and management of POUR. At present, clinical practice includes either preoperative insertion of an indwelling catheter to be removed after 24-48 postoperative hours or postoperative intermittent in-and-out catheterization performed either at scheduled times (every 6-8 hours) or as necessary. Although the most effective approach remains an issue of debate, there is a growing consensus that postoperative intermittent catheterization guided by ultrasound could decrease the incidence of complications related to POUR. The purpose of the present article is to review the published data on the effects of analgesia techniques on the development of POUR after hip and knee arthroplasty. General and regional anesthesia are implicated in the etiology of POUR; however, type and duration do not correlate with its incidence. Of the different postoperative analgesic techniques currently used, continuous peripheral nerve block has the least impact on POUR.