A 73 year-old man was admitted for transureteral prostatic resection (TURP). Spinal anesthesia is preferred for this procedure, since the majority of patients will remain awake, and will complain if there is bladder rupture or hyponatremia due to excessive absorption of fluid instilled into the bladder.
The anesthetist preferred to give this patient a spinal within ester rather than an amide derivative
case author: Hugh S. Mathewson, M.D., Professor Emeritus, School of Allied Health, Department of Nurse Anesthesia, University of Kansas Medical Center
case editor: Michael Gordon, Ph.D.
Ester-derivative local anesthetic:
mepivacaine (Carbocaine)
etidocaine (Duranest)
lidocaine (Xylocaine)
tetracaine (pontocaine)
all the above
What dosage of tetracaine (pontocaine) is usually required for transurethral resection of the prostate (TURP)?
0.5 ml (1 mg tetracaine (pontocaine))
4 ml (-10 mg tetracaine (pontocaine))
40 ml (100 mg tetracaine (pontocaine))
400 ml (10 g tetracaine (pontocaine))
What will be the manifestation of a block that is too high?
hypertension & tachycardia
hypotension & bradycardia (if the level rises high as C4)
no effect as long as the patient is in the Trendelenburg position
Why is tetracaine (pontocaine) a preferred agent for spinal anesthesia?
extremely short duration of action (< 30 minutes)
absence of toxicity
duration of action (1.5-2 hours) about right for many surgical procedures, including TURP
ester-derivatives may be fixed or rapidly to spinal nerves, allowing the sooner positional changes (less chance for block elevation)