To determine the duration of pain relief and efficacy of intraarticular morphine compared with bupivacaine after outpatient knee arthroscopy under local anesthesia, we gave patients one of three postoperative intraarticular injections: 4 mg morphine, 0.25% bupivacaine, or 0.9% saline. Visual analog scale scores and supplemental pain medication use were recorded at 0 to 30 minutes, 2, 4, 6, 8 to 12, and 24 hours after surgery. The score on the visual analog scale at 24 hours was significantly lower in the morphine group than in the bupivacaine or control groups. The cumulative amount of pain medication used was significantly lower in the morphine and bupivacaine groups at 2 to 6 hours after surgery than in the saline control group. The morphine group used the least supplemental pain medication during the 12 to 24 hour interval (P = 0.06). We found that the use of intraarticular morphine or bupivacaine after outpatient knee arthroscopy will decrease the amount of narcotic medication needed for pain relief during the early postoperative period. In addition, morphine provided prolonged pain relief up to 24 hours when compared with bupivacaine or placebo, and the patients in the morphine group tended to take less supplemental pain medication during the first postoperative day.
We postulated that three factors determined the occupational risk of infection from the human immunodeficiency virus (HIV) for surgeons, anesthesiologists, and medical students: first, the risk of needlestick exposure per year (range for surgeons 3.8-6.2, weighted average 4.2; range for anesthesiologists 0.86-2.5, weighted average 1.3; range for third-year medical students 0-5, best estimate 5); second, the risk of seroconversion from a needlestick exposure (0.42%-0.50%); and third, prevalence of HIV in the population served (0.32%-23.6%, depending on geographic location). Thus, the calculated range for occupational risk of HIV infection for a surgeon over a 30-yr period (assuming no change in HIV prevalence or benefit from protective measures) was 0.17%-13.9%; for an anesthesiologist, 0.05%-4.50%. The corresponding range of occupational risk for a medical student during the third year was 0.007%-0.59%. The range of risk is large because the variation in prevalence of HIV infection from one area to another is great. The authors validated the methodology first by using an equation, with estimates from the literature for factors in the equation, to calculate the risk of infection for hepatitis B and then by comparing the results with known rates of infection in the prevaccine era. Calculated occupational risk of hepatitis B infection for anesthesiologists was in the lower range of actual prevalence of infection (calculated range 2.32%-20.6%; known range 6%-26%). Calculated risk versus prevalence for surgeons was fairly close (7.31%-53.4% versus 24.4%).(ABSTRACT TRUNCATED AT 250 WORDS)
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