Prevention of spinal anaesthesia-induced hypotension during caesarean section using noninvasive cardiac output monitoring: A randomised clinical trial.

BACKGROUND

Hypotension following spinal anaesthesia during caesarean section is common and can negatively affect the mother and child.

OBJECTIVE

This study aimed to assess whether spinal anaesthesia-induced hypotension could be prevented using noninvasive cardiac output monitoring.

DESIGN

Randomised controlled study.

SETTING

This single-centre study was conducted at a Japanese hospital from 13 May 2020 to 27 April 2022.

PATIENTS: Women (n = 200) who underwent elective caesarean delivery under spinal anaesthesia were included. The exclusion criteria were age <20 years, ASA physical status ≥3, and contraindications to combined spinal and epidural anaesthesia.

INTERVENTION: The participants were randomised via simple randomisation into the estimated continuous cardiac output-guided vasopressor administration (esCCO group) or control group. Blood pressure was measured at 2.5-min intervals following intrathecal 10 mg hyperbaric bupivacaine injection. Patients in both groups received a single dose of vasopressor (phenylephrine 100 μg or ephedrine 4 mg) if they had hypotension (systolic BP <100 mmHg and/or mean BP <65 mmHg) or nausea. In the esCCO group, phenylephrine was also administered if the esCCO decreased by 10% or more from baseline.

MAIN OUTCOME MEASURES: The primary outcome was the proportion of patients with hypotension (systolic blood pressure < 100 mmHg and/or mean blood pressure < 65 mmHg) between the spinal anaesthesia injection and delivery. The secondary outcomes were nausea and vomiting, reactive hypertension (systolic BP ≥ 140 mmHg), and umbilical arterial blood pH. Fisher's exact test and Student's t-test were used for analysis.

RESULTS

The incidence of hypotension was 43/88 (49%) in the control group and 20/103 (19%) in the esCCO group (P < 0.001). The delivered phenylephrine dose was 186 ± 149 μg in the control group and 262 ± 189 μg in the esCCO group (P = 0.003). The incidences of nausea and vomiting, reactive hypertension, and umbilical arterial blood pH did not differ between the groups.

CONCLUSION

The incidence of hypotension may be reduced using estimated continuous CO monitoring, however, no differences were seen in the incidence of nausea or reactive hypertension, nor in umbilical arterial pH levels.

TRIAL REGISTRATION: UMIN-CTR Clinical Trial Database identifier: UMIN000040066.