Fluid preload in obstetric patients. How to do it?

Area of Science:

• Anesthesiology
• Obstetrics
• Pharmacology

Background:

• Fluid preload effectiveness in preventing hypotension post-spinal anesthesia varies in non-obstetric patients.
• Previous research suggests immediate post-spinal anesthesia fluid preload is superior to pre-block preload.

Purpose of the Study:

• To compare the incidence of arterial hypotension and vasopressor consumption in parturients undergoing C-section under spinal anesthesia.
• To evaluate different fluid preload regimens: timing (pre- vs. post-spinal) and rate (slow vs. fast).

Main Methods:

• Sixty term pregnant women undergoing C-section under spinal anesthesia were randomized into three groups.
• Groups received acute preload (10 ml/kg lactated Ringer's) either before spinal anesthesia or after, with varying infusion rates.
• Blood pressure, vasopressor use (metaraminol), nausea, vomiting, Apgar scores, and umbilical artery pH were monitored.

Main Results:

• The fastest preload rate was achieved in the group receiving fluid post-spinal anesthesia via a 16G catheter with a pressurizer.
• No significant differences were observed between groups regarding the incidence of arterial hypotension, nausea, vomiting, metaraminol consumption, Apgar scores, or umbilical artery pH.

Conclusions:

• Acute fluid preload, whether administered before or after spinal anesthesia, and regardless of infusion rate, does not alter vasopressor consumption or the incidence of maternal hypotension.
• These fluid preload strategies also showed no impact on maternal nausea/vomiting or fetal well-being indicators.