Low-dose versus a higher-dose bupivacaine spinal anesthesia for cesarean delivery.

To the Editor:—We read with interest the article by Langesæter et al. that investigated the hemodynamic effects of a low-dose versus a higher-dose bupivacaine spinal anesthesia for cesarean delivery. While the LiDCOplus (LiDCO Ltd., Cambridge, United Kingdom) monitor for continuous hemodynamic measurements seems promising because of its minimal invasiveness, the use of low-dose bupivacaine for spinal anesthesia during cesarean delivery poses several practical questions. First, we would like to remark that among the various methods studied while incurring less frequent hypotension during cesarean delivery with spinal anesthesia, the only technique to date that has been shown to be effective is the combination of high-dose phenylephrine and crystalloid cohydration. Our primary concern regarding the study by Langesæter et al. is the high incidence (7.5%) of incomplete spinal block encountered with the low-dose local anesthetic. Also, we wonder why the upper target sensory level was T8 and not T4-5, and what the actually recorded upper sensory level of the block with both doses of spinal anesthesia was. In addition, from a practical and safety point of view, it seems illogical to administer prophylactic phenylephrine with a systolic blood pressure of 140 mmHg. The concern that the hemodynamic stability might come on the account of the quality of anesthesia is further emphasized by Ben David et al., who found that with low-dose bupivacaine plus fentanyl, 8 out of 16 patients noted transient pain or pressure with stretching of the incision and/or with uterine fundal pressure at delivery. We believe that a low-dose spinal anesthesia for cesarean delivery should only be employed with the combined spinal-epidural approach where epidural supplementation is feasible (as it was done in the present study). However, such an epidural supplementation may lead to hemodynamic instability by itself. If spinal anesthesia has to be supplemented with epidural local anesthetics, then a rapid-onset local anesthetics such as lidocaine is the preferable option.