Application Of Predicted Normal Body Weight In Propofol TCI On Chinese Obese Patients During Induction And Maintenance Of General Anesthesia

Objective: In order to guide the choice of propofol TCI clinical regimen, wedesigned a randomized controlled trials to help select appropriate weight calculationformula reasonably, by elaborating the effects of pharmacokinetic andpharmacodynamic on obesity and by combining physiological changes of all systemsduring induction and maintenance.Methods: We chose patients of selective subtotal thyroidectomy under generalanesthesia with obesity (BMI>30Kg/m2) in36cases, ASA I to II, age20~65yearsold, BMI32.1~36.4Kg/m2. They were randomly divided into2groups as controlgroup (TBW group), and experimental group (PNWT group) by using the2bodyweight formula TBW and PNWT,17and19patients of each group. Duringinduction of anesthesia, age and calculated weight were input into TCI system andtarget plasma concentration was set from2.5to3.5μg/ml, then fentanyl3g/kg, CISatracurium0.15mg/kg were given. During anesthesia maintenance, propofol targetplasma concentration was set from2.5to3.5g/ml and Remifentanil0.05-0.2μg/kg·min was infused intravenously,then intermittent additional atracurium0.03mg/kg was given1-2times. After thepatients entered the operation rooms, the time points we recordedSBP, DBP, HR, Narcotrend value were as follows: the basic data (T0), Loss ofconsciousness (T1), the time right after intubation (T2), the time right after operationstarted (T3),15min after operation started (T4). The differences in SBP, DBP, HRbetween T1, T2, T3, T4and those at T0were calculated as SBP, DBP, HR andrecorded. In addition, we recorded the total amount of propofol, the times ofvasoactive drugs application and the number of adjustmentsof target concentration during operations.Results:1, In hemodynamics: Compared with T0, two groups of patients at T1～T4SBP, DBP, HR were significantly decreased (P<0.05); compared withT1,two groups of patients at T2, T3, T4SBP, DBP, HR were significantly increased (P<0.05); compared with the T2, DBP, HR SBP of two groups of patients were both decreased significantly at T3, T4(P<0.05); At TO there was no significant difference among SBP, DBP and HR in PNWT group (P>0.05); compared with group TBW, at T1, T2, T3and T4, SBP, DBP, HR in PNWT group were significantly increased (P<0.05). Compared with the T1, ASBP、△DBP and△HR of two groups at T2, T3, T4, significantly decreased (P<0.05); compared with the T2, at T3,T4△SBP, ADBP,△HR of both two groups of patients significantly decreased (P<0.05). Compared with group TBW,△SBP,△DBP,△HR of PNWT group at T1, T2, T3and T4significantly decreased (P<0.05).2, In the quality of waking:compared with TBW group, recovery time of PNWT group was significantly reduced (P<0.05), Ramsay score increased (P<0.05), Steward score decreased (P<0.05); in PNWT group, the dosage of propofol significantly decreased (P<0.05), adjustments of target concentration significantly decreased and application of vasoactive drugs significantly decreased (P<0.05).Conclusion:During propofol TCI in obesity patients, using PNWT formula to input weight comparing with actual total weight into the administration seems more stable in perioperative hemodynamics, reduced the dosage of propofol, shorten recovery time and improve the recovery quality. For propofol target controlled infusion in obese patients during general anesthesia, we suggest that PNWT can be used as reference for weight calculation.