<prompt> Which of the following medications should be dosed according to total body weight TBW, instead of lean body mass in morbidly obese patientsPancuroniumVecuroniumMorphine PCASuccinylcholine  <response>: Succinylcholine should be dosed according to total body weight TBW, not lean body mass. Morbidly obese patients have elevated activity of pseudocholinesterase, the enzyme responsible for the metabolism of succinylcholine. Thus, dosing by total body weight is necessary to ensure complete relaxation prior to intubation. Morphine by PCA, vecuronium, and pancuronium should be dosed according to lean body mass. 