Crystalloid coloading vs. colloid coloading in elective Caesarean section: postspinal hypotension and vasopressor consumption, a prospective, observational clinical trial

Background: Maternal hypotension is a common side effect of spinal anaesthesia for Caesarean section. The combination of colloid coloading and vasopressors was considered our standard for its prevention and treatment. As the safety of hydroxyethyl starch is under debate, we replaced colloid with crystalloid coloading.

Objective: We hypothesize that the mean blood pressure drop is greater when coloading with crystalloids.

Design: Prospective, observational clinical trial.

Setting: Two-centre study conducted in Berlin, Germany.

Patients: Parturients scheduled for a Caesarean section were screened for eligibility.

Intervention: The study protocol and patient monitoring were based on the standard operating procedure for Caesarean section in both centres. The data from the crystalloid group were prospectively collected between November 2014 and July 2015.

Main outcome measures: The primary endpoint was the median drop in mean blood pressure after induction of spinal anaesthesia. Secondary endpoints were incidence of hypotension (drop > 20% of baseline systolic pressure /drop < 100 mmHg), vasopressor and additional fluid requirements (mL), incidence of bradycardia (heart rate < 60 beats per minute), blood loss, Apgar score, and umbilical artery pH. In case of hypotension, patients received phenylephrine or cafedrine/theodrenaline according to their heart rate. A p < 0.05 was considered significant.

Results: 345 prospectively enrolled patients (n = 193 crystalloid group vs. n = 152 colloid group) were analysed. The median drop in mean blood pressure was greater in the crystalloid group [34 mmHg (25; 42 mmHg) vs. 21 mmHg (13; 29 mmHg), p < 0.001]. Incidences of hypotension [93.3% vs. 83.6%, p: 0.004] and bradycardia [19.7% vs. 9.9%, p: 0.012] were also significantly greater in the crystalloid group. Vasopressor requirements, blood loss and neonatal outcome were not different between the groups.

Conclusions: Crystalloid coloading was associated with a greater drop in mean blood pressure and a higher incidence of hypotension when compared with colloid coloading. Neonatal outcome was, however, unaffected by the type of fluid.

Trial registration: DRKS00006783 ( http://www.drks.de ).