ABSTRACT
Background Occupational noise-induced hearing loss (NIHL) is one of the most prevalent occupational diseases in the world. With the development of industry, noise sources in the workplace have become increasingly complex. Objective To apply kurtosis-adjusted cumulative noise exposure (CNE) to assess the occupational hearing loss among furniture manufacturing workers, and to provide a basis for revising noise measurement methods and occupational exposure limits in China. Methods A cross-sectional survey was conducted to select 694 manufacturing workers, including 542 furniture manufacturing workers exposed to non-Gaussian noise, and 152 textile manufacturing workers and paper manufacturing workers exposed to Gaussian noise. The job titles involving non-Gaussian noise were gunning and nailing, and woodworking, while those involving Gaussian noise were weaving, spinning, and pulping. High frequency noise-induced hearing loss (HFNIHL) and noise exposure data were collected for each study subject. Noise energy metrics included eight-hour equivalent continuous A-weighted sound pressure level (LAeq,8 h) and CNE. Kurtosis was a noise temporal structure metric. Kurtosis-adjusted CNE was a combined indicator of noise energy and temporal structure. Results The age of the study subjects was (35.64±10.35) years, the exposure duration was (6.71±6.44) years, and the proportion of males was 75.50%. The LAeq,8 h was (89.43±6.01) dB(A). About 81.42% of the study subjects were exposed to noise levels above 85 dB(A), the CNE was (95.85±7.32) dB(A)·year, with a kurtosis of 99.34 ± 139.19, and the prevalence rate of HFNIHL was 35.59%. The mean kurtosis of the non-Gaussian noise group was higher than that of the Gaussian noise group (125.33±147.17 vs. 5.86±1.94, t=−21.04, P<0.05). The results of binary logistic regression analysis showed that kurtosis was an influential factor of workers' HFNIHL after correcting for age, exposure duration, and LAeq,8 h (OR=1.49, P<0.05). The results of multiple linear regression analysis showed that the effects of age, exposure duration, LAeq,8 h, and kurtosis on noise-induced permanent threshold shift at frequencies of 3, 4, and 6 kHz of the poor hearing ear were statistically significant (all P<0.05). The results of chi-square trend analysis showed that when CNE ≥ 90 dB(A)·year, the HFNIHL prevalence rate elevated with increasing kurtosis (P<0.05). The mean HFNIHL prevalence rate was higher in the non-Gaussian noise group than in the Gaussian noise group (31.7% vs. 22.0%, P<0.05). After applying kurtosis-adjusted CNE, the linear equation between CNE and HFNIHL prevalence rate for the non-Gaussian noise group almost overlapped with that for the Gaussian noise group, and the mean difference in HFNIHL prevalence rate between the two groups decreased from 9.7% to 1.4% (P<0.05). Conclusion Noise kurtosis is an effective metric for NIHL evaluation. Kurtosis-adjusted CNE can effectively evaluate occupational hearing loss due to non-Gaussian noise exposure in furniture manufacturing workers, and is expected to be a new indicator of non-Gaussian noise measurement and assessment.
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Objective To compare the BIS values in patients under anesthesia with minimum alveolar concentration (MAC) of sevoflurane and median effective concentration (EC50) of propofol at loss of consciousness.Methods Sixty ASA Ⅰ or Ⅱ patients,aged 18-60 yr,undergoing elective surgery under general anesthesia,were equally and randomly divided into 2 groups:inhalational anesthesia with sevoflurane group (group Sev) and intravenous anesthesia with propofol ( group Pro).The end-tidal concentration of sevoflurane was monitored using Aestiva anesthesia machine (Datex Ohmeda) in group Sev.Anesthesia was induced with intravenous injection of etomidate 0.3 mg/kg,rocuronium 1 mg/kg,and remifentanil 0.2 μg/kg.The patients were mechanically ventilated after tracheal intubafion.Sevoflurane inhalation was started 12.5 min after intubation in group Sev.Propofol was given by target-controlled infusion with the target plasma concentration set at 3.8 μg/ml 12.5 min after intubation in group Pro.When the effect-site concentrations of propofol reached EC50 of propofol at loss of consciousness (2.2 μg/ml),1.3 EC50(2.86 μg/ml) and 1.5 EC50 (3.3μg/ml) and when the end-tidal concentrations of sevoflurane reached 1.0,1.3 and 1.5 MAC,BIS value,MAP and HR were recorded.Results HR was significantly higher at 1.3 MAC or 1.3 EC50,and at 1.5 MAC or 1.5 EC50 in group Pro than in group Sev ( P ＜0.05).BIS value was significantly decreased at 1.3 MAC or 1.3 EC50,and at 1.5 MAC or 1.5 EC50 compared with that at 1.0 MAC or EC50(P ＜0.05).There was no significant difference in MAP and BIS value at each time point between the two groups ( P ＞ 0.05).Conclusion No significant change in BIS values is found in patients under anesthesia with 1.0,1.3 and 1.5 MAC of sevoflurane and with 1.0,1.3 and 1.5 EC50 of propofol.
ABSTRACT
Objective To evaluate the efficacy of nalmefene antagonizing postoperative respiratory depression induced by opioids.Methods Two hundred and forty ASA Ⅰ orⅡpatients aged 18-64 yr with body weight fluctuating within 20% of the standard body weight were included in this multicenter,randomized,double-blind,positive drug-controlled study.Anesthesia was induced with etomidate 0.3 mg/kg and TCI of sufentanil(effect-site concentration 0.4.ng/ml).Tracheal intubation was facilitated with vecuronium 0.1 mg/kg or rocuronium 0.6mg/kg.The patients were mechanically ventilated.PETCO2 was maintained at 35-45 mm Hg.Anesthesia was maintained with sevoflurane+ sufentanil TCI(Ce=0.1-0.4 ng/ml).Patients undergoing neurosurgery and liver or kidney operation were excluded.The operation time was within 3 h.The residual effects of muscle relaxants were reversed after operation.The patients were randomly divided into 2 groups(n=120 each):group Ⅰneloxone andgroup Ⅱ nalmefene.Naloxone 0.1 mg or nalmefene 0.25 μg/kg was injected iv over 30 s and was repeated 5 min later if necessary until the respiratory rate＞10 bpm,PETCO2＜45 mm Hg and apnea time＜15 s.The total amount of naloxone was≤0.4 mg while that of nalmefene≤1 μg/kg.BP,HR,SpO2,PETCO2,respiratory rate and apnea time were recorded immediately before and at 2 and 5 min after haloxone/nalmefene administration and then every 5 min until 5 min after extubation.The recovery of spontaneous breathing within 30 min after naloxone/nalmefene administration,extubation time and Ramsay sedation score at 5 min after extubation were recorded.The patients were also observed for adverse reactions.Results Spontaneous breathing recovered within 30 min after naloxone/nalmefene administration in all patients in both groups.The extubation time was significantly shorter in nalmefene group than in naloxone group.There was no significant difference in Ramsay sedation score,BP,HR,SpO2 and incidence of adverse reactions between the 2 groups.Conclusion Nalmefene is better than naloxone in antagonizing opioid-induced postoperative respiratory depression.