Genotoxicity related to waste anaesthetic gas exposure is controversial. We have investigated the frequency of sister chromatid exchanges in peripheral lymphocytes of operating room personnel exposed to trace concentrations of isoflurane and nitrous oxide. Occupational exposure was recorded using a direct reading instrument. Frequencies of sister chromatid exchanges were measured in lymphocyte cultures of 27 non-smokers working in the operating room and 27 non-smoking controls. Personnel were exposed to an 8-h time-weighted average of nitrous oxide 11.8 ppm and isoflurane 0.5 ppm. After exposure, sister chromatid exchange frequency was increased significantly (mean 9.0 (SD 1.3) vs 8.0 (1.4) in exposed and control personnel, respectively) (P < 0.05). We conclude that exposure to even trace concentrations of waste anaesthetic gases may cause genetic damage comparable with smoking 11-20 cigarettes per day.

A high level of occupational exposure to inhaled anesthetics is associated with genotoxicity (as defined by formation of micronucleated lymphocytes), whereas a low-level exposure (within National Institute of Occupational Safety and Health limits) is not.

Objectives-To evaluate genetic damage as the frequency of sister chromatid exchanges and micronuclei in lymphocytes of peripheral blood of operating room personnel exposed to waste anaesthetic gases. Methods-Occupational exposure was measured with a direct reading instrument. Venous blood samples were drawn from 10 non-smokers working in the operating room and 10 non-smoking controls (matched by age, sex, and smoking habits). Lymphocytes were cultured separately over 72 hours for each assay with standard protocols. At the end of the culture time, the cells were harvested, stained, and coded for blind scoring. The exchanges of DNA material were evaluated by counting the number of sister chromatid exchanges in 30 metaphases per probe or by counting the frequency of micronuclei in 2000 binucleated cells. Also, the mitotic and proliferative indices were measured. Results-The operating room personnel at the hospital were exposed to an 8 hour time weighted average of 12.8 ppm nitrous oxide and 5.3 ppm isoflurane. The mean (SD) frequency of sister chromatid exchanges was significantly higher (10.2 (1.9) v 7.4 (2.4)) in exposed workers than controls (p=0.036) the proportion of micronuclei (micronuclei/500 binucleated cells) was also higher (8.7 (2.9) v 6.8 (2.5)), but was not significant (p=0.10). Conclusion-Exposure even to trace concentrations of waste anaesthetic gases may cause dose-dependent genetic damage. Concerning the micronuclei test, no clastogenic potential could be detected after average chronic exposure to waste anaesthetic gas. However, an increased frequency of sister chromatid exchanges in human lymphocytes could be detected. Although the measured diVerences were low, they were comparable with smoking 11-20 cigarettes a day. Due to these findings, the increased proportion of micronuclei and rates of sister chromatid exchanges may be relevant long term and need further investigation. (Occup Environ Med 1999;56:433-437)

Compared to the conventional group, enhanced aesthetic results with consecutive reduction of secondary refinements could be achieved when using our modified flap harvesting and shaping techniques, as well as our methods for reducing contour deformities after rib resection and for overcoming donor site morbidities.

A 39-year-old patient developed phantom pain after amputation of both upper arms following a burn injury. The pain did not respond to naproxen, morphine, carbamazepine, amitriptyline, calcitonin or transcutaneous electrical nerve stimulation (TENS). At the 39th post-operative day an axillary catheter was placed on the right side, as well as an interscalene catheter on the left. Ropivacaine 0.2% was infused, starting with a rate of 4 ml/h, that was increased to 6 ml/h during the subsequent 6 days. Within 20 min of catheter placement complete pain relief was achieved. The patient did not need any other analgesics and remained painfree for 7 months. Neither motor block, nor any other side effects occurred during the infusion of ropivacaine 0.2%. Thus, the patient not only received analgesia, but also got an effective treatment of established phantom pain. A similar approach with bupivacaine may not have been feasible, because of the possibility of toxic side effects. Ropivacaine is a long-acting local anaesthetic which is less toxic than bupivacaine and has the additional advantage of producing less motor-blockade in the concentration used, so the patient was able to move actively without experiencing any pain.