Dose Adjustment for Obese patients

From Ingrade, et al. Dose Adjustment of anesthetics in the morbidly obeseBr. J. Anaesth. (2010) 105 (suppl 1): i16-i23.doi: 10.1093/bja/aeq312 

Drug Dosing scalar Comments
Thiopental Induction: LBW

Maintenance: TBW

Simulations showed a 60% decrease in peak plasma concentration in MO subjects compared with lean subjects after a 250 mg dose.26 Induction dose adjusted to LBW results in same peak plasma concentration as dose adjusted to CO.26 Volumes and clearances increase proportionally with TBW.25
Propofol Induction: LBW

Maintenance: TBW

MO subjects given an induction dose based on LBW required similar amounts of propofol and similar times to loss of consciousness compared with lean subjects given propofol based on TBW.29 Volume of distribution and clearance at steady state increases with increasing TBW.28
Fentanyl LBW Clearance increases linearly with ‘PK mass’, an arbitrary scalar highly correlated to LBW.46
Remifentanil LBW An infusion based on LBW results in similar plasma concentrations as normal weight subjects were given an infusion based on TBW.51
Succinylcholine TBW Administration of 1 mg kg−1 based on TBW resulted in a more profound block and better intubating conditions compared with doses based on IBW or LBW.67
Vecuronium IBW Doses based on TBW result in a prolonged duration of action in obese vs non-obese subjects.69 70
Rocuronium IBW There is an increased duration of action when the drug is given based on TBW vs IBW.71
Atracurium, Cisatracurium IBW The duration of action is prolonged in obese subjects when given on the basis of TBW vs IBW.73 74

 

 

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