Effective local anaesthetic volumes for sciatic nerve blockade: a clinical evaluation of the ED99.

Previous results in volunteers have indicated the effective dose in 99% of subjects (ED99 ) of local anaesthetic volume to be 0.10 ml.mm(-2) of cross-sectional nerve area for sciatic nerve blockade. The objective of this prospective, randomised, double-blind study was to investigate the ED99 of local anaesthetic for ultrasound-guided sciatic nerve blockade in patients undergoing foot surgery, according to Dixon's up-and-down method and probit analysis. A starting volume of 0.20 ml local anaesthetic per mm(2) cross-sectional nerve area was used. If surgical anaesthesia was judged to be adequate, the volume of local anaesthetic for the next case was reduced by 0.02 ml.mm(-2), until the first block failed. Thereafter, the volume of local anaesthetic was increased by 0.02 ml.mm(-2). The ED99 volume of local anaesthetic for ultrasound-guided sciatic nerve blockade was calculated to be 0.15 ml.mm(-2) cross-sectional nerve area, which is higher than the previously evaluated ED99 volume in volunteers.

Objective and subjective evaluation of donor-site morbidity after nipple sharing for nipple areola reconstruction.

Nipple reconstruction is of importance in achieving the best possible aesthetic outcome after breast reconstruction. Nipple sharing is a common technique; this study focused on the potential morbidity at the donor nipple. Between 2008 and 2012, 26 patients underwent nipple sharing at our institution. The donor nipple was examined before and after the procedure (mean follow-up of 21 months). Sensitivity, projection, diameter, and patient satisfaction were evaluated. The sensitivity in the donor nipple decreased, albeit insignificantly, from 1.2 g/mm2 (0.8-1.6) to 1.8 g/mm2 (0.8-4.8) (p=0.054, n=26). The projection due to graft removal decreased from 8.0 mm (6.8-10.0) to 4.5 mm (4.0-5.0) (p=0.001). Of the patients, 88% were "very satisfied" or "somewhat satisfied" with the sensitivity and 89% with the symmetry between the donor and reconstructed nipple. At least 60% of the patients were "very satisfied" with all aesthetic outcome parameters (projection, appearance, naturalness, color, and shape). All patients would agree to undergo this procedure again, if necessary. Nipple sharing was associated with minimal morbidity at the donor nipple. The postoperative projection was adequate. Regardless of whether simultaneous mastopexy was performed, the loss of sensitivity was minimal and presumably imperceptible to the patient. By using no sutures after graft removal and letting the donor nipple heal spontaneously, scarring was minimized and the natural appearance and good sensitivity of the donor nipple were preserved.

High-level, but not low-level, occupational exposure to inhaled anesthetics is associated with genotoxicity in the micronucleus assay.

UNLABELLED: To minimize the possible health risks posed by waste anesthetic gases, the National Institute of Occupational Safety and Health (NIOSH) recommends exposure limits. We investigated the genotoxicity of a previously established occupational exposure exceeding these limits (high-level exposure) and of one within these limits (low-level exposure). Genotoxicity was assessed by the formation of micronucleated lymphocytes in 25 anesthetists and anesthetic nurses of an Eastern European (High-Level Exposure Group) and a German (Low-Level Exposure Group) university hospital. Each exposed group was compared with a group of nonexposed personnel of the same hospital. Compared with its Control Group, there was an increased fraction of micronucleated lymphocytes per 1000 binucleated cells in the High-Level Exposure Group (median 14.0, range 9.0-26.7 vs median 11.3, range 3.2-19.4; P < 0.05) but not in the Low-Level Exposure Group (median 9.8, range 4.2-20.0 vs median 10.5, range 5.0-20.5). We conclude that a high-level exposure to inhaled anesthetics is associated with an increase in chromosome damage, and measures are recommended to decrease exposure levels. As evidenced by the formation of micronucleated lymphocytes, the threshold values recommended by NIOSH appear to be safe. IMPLICATIONS: 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.

[Biological monitoring during exposure to the anesthetics isoflurane and sevoflurane]. / Biologisches Monitoring bei Exposition durch die anästhetika Isofluran und Sevofluran.

Exposure to traces of inhaled anaesthetic agents may impair the health of the operating theatre personnel. Although no cause-effect relationship has been found, most public health authorities recommend various occupational exposure standards to minimize possible health risks. If metabolites of the substances are known, biological monitoring is an alternative to the monitoring of the operating theatre's air. The new anaesthetic agent Sevoflurane is considerably more transformed to fluoride than Isoflurane. Concerning fluoride there exist Biological Tolerance Values of 4.0-7.0 mg fluoride (F-) per gram creatinine (Crea). The aim of our study was to compare the fluoride excretion under the occupational exposure to sevoflurane and isoflurane. By the means of a direct-reading instrument trace concentrations of sevoflurane, isoflurane, and nitrous oxide were measured during 40 anaesthetic procedures. Urine samples were collected before (Z1) and after the workshift (Z2), and in the morning of the next day (Z3). The analysis was done by the means of an ionselective electrode. The personnel-related concentrations (median, range) were 0.50 (0.16-7.04) ppm isoflurance and 27.36 (5.87-467.10) ppm nitrous oxide, and 0.79 (0.15-1.95) ppm sevoflurane and 17.74 (2.45-84.20) ppm nitrous oxide. The resulting fluoride values presented at Z1, Z2, and Z3 as median (range) during exposure to isoflurane were 0.15 (0.11-0.53), 0.19 (0.11-0.53), 0.20 (0.11-0.31) mg F-/g Crea, and 0.15 (0.10-0.46), 0.22 (0.13-0.44), 0.23 (0.15-0.69) mg F-/g Crea during exposure to sevoflurance, respectively. The trace concentrations were clearly under 10 ppm for the volatile substances and 100 ppm for nitrous oxide. The values are comparable to data recorded under similar working conditions. The measured fluoride values were low and remained under the legal tolerance values. Under the described conditions potential health risks were low.

Genetic damage in operating room personnel exposed to isoflurane and nitrous oxide.

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 differences 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.

Recollection of dreams after short general anaesthesia: influence on patient anxiety and satisfaction.

BACKGROUND AND OBJECTIVE: We ascertained whether dreams during short general anaesthesia influence subsequent patient satisfaction and anxiety. METHODS: Fifty female patients were randomized into two groups to test for a difference between intravenous and inhalational anaesthesias. In Group Propo, anaesthesia was induced and maintained with propofol; in Group Metho-Iso, anaesthesia was induced with methohexital and maintained with isoflurane. Satisfaction and anxiety with anaesthesia were evaluated using a visual analogue scale from 0 to 100. Dream incidence rate, satisfaction and anxiety were assessed from immediately after waking until 3 months later. RESULTS: Seventeen patients (34%) dreamed during anaesthesia. There were no significant differences in satisfaction or anxiety after anaesthesia between the dreaming and non-dreaming patients (satisfaction, 92.3 +/- 21.6 versus 92.1 +/- 21.6; anxiety, 21.1 +/- 21.1 versus 30.3 +/- 32.1), or between Group Propo and Group Metho-Iso (satisfaction, 94.4 +/- 19.3 versus 90.0 +/- 23.4; anxiety, 26.0 +/- 27.6 versus 28.4 +/- 30.7). There was no significant difference in the incidence rate of dreaming with the type of anaesthesia used (Group Propo, 11 patients; Group Metho-Iso, 6 patients). CONCLUSIONS: Dreaming during general anaesthesia is common but does not influence satisfaction or anxiety after anaesthesia.

Waste anaesthetic gases induce sister chromatid exchanges in lymphocytes of operating room personnel.

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.