To the Editor:—

Ben-David et al.  1have shown the advantages of combined low-dose bupivacaine and fentanyl spinal anesthesia versus  a “conventional” dose of 10 mg bupivacaine. The 90% incidence of hypotension in the 10-mg bupivacaine group is very high (one of the disadvantages of including a small number of patients). This could have been minimized if the authors had chosen a smaller dose for the control group. Biboulet et al.  2considered a dose of 5 mg intrathecal bupivacaine to be “too high” to limit the block to T10 in geriatric patients because of a 40% incidence of hypotension. Moreover, Ben-david et al.  3have shown that a dose of 7.5 mg bupivacaine can produce an acceptable block up to T8. Choosing a 10-mg dose as a control in this study that involved geriatric patients exacerbated the differences among the two groups.

The authors did not mention anything about the quality of motor block in the minidose bupivacaine group. A previous study with 5 mg bupivacaine showed that in nearly 80% of the patients a Bromage scale score of 2 or 3 was not achieved. 3 

I wonder whether the incidence of hypotension could be further lowered if “unilateral” spinal were attempted. It has been shown that glucose-free bupivacaine is hypobaric 4and, in low doses, can be used to provide satisfactory unilateral block and hemodynamic stability. 5This may be particularly useful in geriatric patients who are likely to be more sensitive to the sympathetic blockade induced by intrathecal local anesthetics.

References

1.
Ben-David B, Frankel R, Arzumonov T, Marchevsky Y, Volpin G: Minidose bupivacaine–fentanyl spinal anesthesia for surgical repair of hip fracture in the aged. A nesthesiology 2000; 92: 6–10
2.
Biboulet P, Deschodt J, Aubas P, Vacher E, Chauvet P, D’Athis F: Continuous spinal anesthesia: Does low-dose plain or hyperbaric bupivacaine allow the performance of hip surgery in the elderly? Reg Anesth 1993; 18: 170–5
3.
Ben-David B, Levin H, Solomon E, Admoni H, Vaida S: Spinal bupivacaine in ambulatory surgery: The effect of saline dilution. Anesth Analg 1996; 83: 716–20
4.
Blomqvist H, Nilsson A: Is glucose free bupivacaine isobaric or hypobaric? Reg Anesth 1989; 14: 195–8
5.
Kuusniemi KS, Pihlajamaki KK, Pitkanen MT, Korkeila JE: A low dose hypobaric bupivacaine spinal anesthesia for knee arthroscopies? Reg Anesth 1997; 22: 534–8