Relationship Between Modified Wilson Sedation Scale And Respiratory Depression By Intravenous Midazolam And Fentanyl For Sedation During Regional Anesthesia

Background: The modified Wilson sedation scale provides a simple and reliable means by which to assess and monitor intraoperative sedation, but the correlation between respiratory depression and the different modified Wilson sedation scale was unclear. Therefore, the purpose of this study was to investigate the incidence of respiratory depression using midazolam and fentanyl as sedative agents and provide a sedative strategy during regional anesthesia.Methods: Two hundred and forty ASA physical statusâ… -â…¡patients, aged 18-60yr, weighing 40-80kg, undergoing regional anesthesia were enrolled in this multi-center clinic study. The patients were randomly arranged to four modified Wilson sedation scale groups (groupl,2, 3 and 4, 60 patients in each group). All patients received midazolam ling and fentanyl 50ug every 5 rain intravenously until sedation scales of 1(groupl), 2(group2), 3(group3) and 4(group4) were achieved respectively. The baseline of SpO₂, RR, PetCO₂, HR and Bp and the changes were recorded every 5minutes for 40min after the modified Wilson sedation scale was achieved. The respiratory complications were also recorded.Results: Compare to the baseline, the SpO2 in all patients significantly decreased (p＜0.01). 18.33 % patients in group3 and 31.67% patients in group4 experienced desaturation (SpO₂＜90%) and required assisted ventilation when the planned sedation levels were not achieved. The SpO₂ in groups 1, 2 and 3 recovered to baseline in 5min, 40min and 35min, respectively but in group4 it didn't recover in 40rain.Compare to the baseline, the RR of patients in groupsl,2,3and4 decreased 11.13%, 24.43%, 25.97%, 36.60%, respectively (p＜0.01). The RR in groupsl and 2 recover to baseline in 15min and 30min, respectively but in groups 3 and 4 it didn't recover in 40min. Compare to the baseline, the PetCO2 of patients in groupsl,2,3and4increased 5.31%, 11.76%, 11.20%, 17.00%, respectively (p＜0.01) . The PetCO₂ in groupsl and 2 recover to baseline in 25min and 30min, respectively but in groups 3 and 4 it didn't recover in 40min. The incidences of respiratory complications were shown in table 2.Conclusion: Sedation using midazolam and fentanyl during regional anesthesia caused the respiration depression, and it aggravated with the increase of sedation level. The respiratory depression in the sedation with the modified Wilson sedation scales of 3 and 4 was severe and it usually required assisted ventilation. Modified Wilson sedation scales of 1 and 2 were safe during regional anesthesia.