Body Surface Area and Age as a Guidance of the Dose
of Intrathecal 0.5% Heavy Bupivacaine and Fentanyl in
Transurethral Procedures
Puttipannee Vorrakitpokatorn MD*, Kamthorn Tantivitayatan MD**,
Yanisa jiranuntakarn MD***, Isara Jongcharoenkamon MD****
Affiliation :
* Department of Anesthesiology, Siriraj Hospital, Mahidol University, Bangkok, Thailand
** Consultant Anesthesiologist, Golden Jubilee Medical Center, Nakhon Prathom, Thailand
*** Anesthesia Unit, Nongkai Hospital, NongKai, Thailand
**** Anesthesia Unit, Nangrong Hospital, Burirum, Thailand
Objective : Observe the potency of various drugs doses as milliliters of 0.5% heavy bupivacaine with or without fentanyl
for spinal block in transurethral cystoscopic procedures. These doses were calculated from patients and drugs’ characteristic
risk factors that interfered with intrathecal drugs spread as weight, height, age, volume, and baricity. Various doses of
fentanyl were also added to increase potency of block as necessary except the oldest group.
Material and Method: One hundred fi fty two ASA I-III adult patients, of both sexes, aged 19 to 80 years, and scheduled for
elective transurethral cystoscopic surgery, were allocated into four groups of age and doses (formulated by earlier studies
and the authors’ own experiences). Group 1 was the 16 to 59-years-old, n = 32, and received [0.5% hyperbaric bupivacaine
in ml (= 5/4 body surface area) + 12.5 mcg fentanyl]. Group 2 was the 60 to 70-years-old group, n = 65, and received
[0.5% hyperbaric bupivacaine in ml (= 1 body surface area) + 10 mcg fentanyl]. Group 3 was the 71 to 75-years-old group,
n = 35, and received [0.5% hyperbaric bupivacaine in ml (= 3/4 body surface area) + 7.5 mcg fentanyl]. Finally, group 4
was the > 75 years old, n = 20, and received [0.5% hyperbaric bupivacaine in ml (= 3/4 body surface area) without fentanyl].
The statistical analysis included hemodynamic parameters and side effects. Post-hoc analysis was done using ANOVA
among the four groups and logistic regression to fi nd any association with successful outcomes.
Results : Eighty-eight percent of the blocks were successful without analgesic supplements (VAS < 2). The mean onset time
(sensation loss to T10) of patients started at 5.4 ± 1.4 minutes, time to regress to T11 (expected duration of operable time)
was 119.7 ± 37.9 (45-255) minutes, time to leg up (expected ready to discharge) 132 ± 39 (65-250) minutes. Hypotension
was strikingly low in the study (8%), while bradycardia was 16%, similar to other reports. The other side effects were
pruritus 2%, nausea 7%, and vomiting 1%. Total successful without any supplement was 87.5% but increase to 93.4%
with low dose of fentanyl < 50 mcg intravenously. The formulas predicted less successful blocks for the oldest age groups
that LA dose less than 1 BSA, and fentanyl added had a signifi cant weight on the outcomes (OR 1.2635, 95% CI
1.0719 -1.4894).
Conclusion : Age and body surface area guided spinal anesthesia is safe. The dose of bupivacaine is lower when combined
with fentanyl. Furthermore, hemodynamic stability is better. The technique is suitable for transurethral procedure within
60 minutes but not in longer operation time. Additionally, it needs patients’ cooperation due to less potent of motor and
pressure sensation block.
Keywords : Hyperbaric bupivacaine, Intrathecal fentanyl, Spinal anesthesia, Transurethral cystoscopic surgery, Body surface
area (BSA)
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