Preload or coload for spinal anesthesia for elective Cesarean delivery: a meta-analysis.
BACKGROUND
Hypotension following spinal anesthesia for Cesarean delivery is common. Fluid loading is recommended to prevent hypotension, but preload is often ineffective. In non-pregnant patients, coloading has been shown to better maintain cardiac output after spinal anesthesia. The purpose of this meta-analysis was to determine whether the timing of the fluid infusion, before (preload) or during (coload) induction of spinal anesthesia for Cesarean delivery, influences the incidence of maternal hypotension or neonatal outcome.


METHODS
We retrieved randomized controlled trials that compared a fluid preload with coload in patients undergoing spinal anesthesia for elective Cesarean delivery. We graded the articles for quality of reporting (maximum score = 5) and recorded the incidence of hypotension, lowest blood pressure, the incidence of maternal nausea and vomiting, umbilical cord pH, and Apgar scores. We combined the results using random effects modelling.


RESULTS
We retrieved eight studies comprised of 518 patients. The median quality score for the published studies was three. The incidence of hypotension in the coload group was 159/268 (59.3%) compared with 156/250 (62.4%) in the preload group (odds ratio [OR] = 0.93; 95% confidence interval [CI] 0.54-1.6). There were no significant differences between groups in any of the other outcomes.


CONCLUSIONS
It is unnecessary to delay surgery in order to deliver a preload of fluid. Regardless of the fluid loading strategy, the incidence of maternal hypotension is high. Prophylactic or therapeutic vasopressors may be required in a significant proportion of patients.
Division of Obstetrical Anesthesia and the Obstetrical Anesthesia Research Unit of the Sunnybrook Research Institute, Sunnybrook Health Sciences Centre at Women's College Hospital, University of Toronto, Toronto, Ontario, M5S 1B2, Canada.
Arnab
A
Banerjee
Renato M
RM
Stocche
Pamela
P
Angle
Stephen H
SH
Halpern
D000775:Anesthesia, Spinal / Q000009:adverse effects / Q000379:methods*; D002585:Cesarean Section; D017558:Elective Surgical Procedures; D005260:Female; D005440:Fluid Therapy / Q000379:methods; D006801:Humans; D007022:Hypotension / Q000209:etiology / Q000517:prevention & control*; D007231:Infant, Newborn; D011247:Pregnancy; D011256:Pregnancy Outcome; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000627:therapeutic use
D014662:Vasoconstrictor Agents