Comparison Of The Effects Of Dexmetomidine And Midazolam On Duration Of Non-hypoxic Apnoea During Induction Of General Anesthesia

ObjectiveTo investigate the effect of dexmedetomidine hydrochloride and midazolam on the duration of non-hypoxic apnoea during induction of general anesthesia.Methods120 female patients underwent elective surgery under general anesthesia（75cases of gynecology and 45 cases of breast surgery）,ASA I-II,were selected.According to the random number table method,they were randomly divided into control group（group C）,midazolam group（group M）and dexmedetomidine group（group D）with 40 cases in each group.In group C,2ml saline was injected intravenously,and then 40ml saline was injected by pump before induction.In group M,midazolam 0.02mg/kg（diluted to 2ml）was injected intravenously,followed by 40ml saline was injected by pump before induction.In group D,2ml saline was injected intravenously,then dexmetomidine 0.5μg/kg（diluted to 40ml）was injected by pump before induction.The pumping time is10 minutes.The oxygen is then pre-absorbed using a closed mask（3 minutes）.Endotracheal intubation at the end of venous induction（The drugs used were fentanyl,etomidate and rocuronium）.Duration of non-hypoxic apnoea,which the time from the injection of rocuronium to the SpO₂ down to 92%,was recorded.Do not assist or control breathing during these operations.Arterial blood was extracted for arterial blood gas analysis at the time of entering the operating room（BG1）,at the end of pumping the drug（or saline）（BG2）,after 3minutes of pre-oxygenation（BG3）,and SpO₂ drops to 92%（BG4）.Monitor and record the patients’heart rate（HR）and mean arterial pressure（MAP）at the time of entering the operation room（Ta）,starting pre-oxygenation（Tb）,beginning of general anesthesia induction（Tc）,pushing the muscle relaxant immediately（Td）,completing tracheal intubation（Te）,Oxygen saturation down to 92%（Tf）and Oxygen saturation return to 99%（Tg）.Results1.The duration of non-hypoxic apnoea in group D was significantly longer than that in group C and M（P<0.05）,the duration of non-hypoxic apnoea of group D is about 28 seconds longer than that in group M.2.There was no significant difference in MAP and HR among the three groups at time Ta.However,in each subsequent recording time point after the time Ta,the HR of group D was significantly lower than that of group C and group M（P<0.05）.At the time of Tb,the HR of the M group was significantly lower than that of the C group（P<0.05）.3.There was no significant difference in arterial blood oxygen partial pressure and carbon dioxide partial pressure between the three groups at each time（P>0.05）.ConclusionCompared with midazolam,dexmetomidine has a longer duration of non-hypoxic apnoea,and is relatively safer in the peri-intubation period.