Prevention and treatment of hypotension during epidural analgesia
NICE have issued guidance on intrapartum care for women including pain relief in labour and regional analgesia. The NICE guidance relevant to hypotension during regional analgesia in labour is as follows:
-
Always secure intravenous access before starting regional analgesia.
-
Preloading and maintenance fluid infusion need not be administered routinely.
-
During establishment of regional analgesia or after further boluses (10ml of epidural mix or more), measure blood pressure every 5 minutes for 15 minutes.
-
Assess the level of sensory block hourly1.
In addition, ensure a vasopressor is to hand (ephedrine or phenylephrine).
If hypotension does occur:
-
Turn the patient into the left lateral position to relieve aortocaval compression.
-
Stop uterotonics.
-
Give oxygen via a facemask.
-
Consider a fluid bolus of 500 mls of crystalloid solution and reassess.
-
Give phenylephrine iv in 100 microgram increments or as an infusion as required. If maternal heart rate is low, consider ephedrine in 6mg increments.
-
Consider obstetric causes of hypotension and discuss with the obstetric team.
Prevention and treatment of hypotension during spinal or epidural anaesthesia for caesarean section
Hypotension after spinal block or an epidural top-up for caesarean section is extremely common and could lead to reduced perfusion to the fetus and fetal distress2. We should therefore aim to prevent hypotension and to treat it promptly. A study has shown that a systolic blood pressure near to the baseline level yields the best cord gases and produces less nausea and vomiting in the mother3.
The most recent guidance has been issued by the International Consensus statement on the management of hypotension during CS4 and NICE5. These reflect our current practice:
-
Preloading and maintenance fluid infusion should be administered; however, it should not delay the initiation of spinal anaesthesia in order to give a fixed volume. Plasmalyte® is used in our Trust for pre-loading.
-
The aim should be to maintain systolic arterial pressure at >90% of an accurate baseline obtained before spinal anaesthesia, and avoid a decrease to < 80%.
-
A phenylephrine infusion is recommended using a syringe pump, and can be started at 10-30ml/hr, immediately after the spinal injection. This can be titrated to BP. Top up boluses may be needed. Ephedrine can be used as an additional agent, especially with low heart rate.
-
The operating table for CS should have a lateral tilt of 15 degrees or appropriate uterine displacement once the woman is in a supine position, because this reduces maternal hypotension5.
If using phenylephrine, dilute a 10mg ampoule of phenylephrine in 100mls of sodium chloride 0.9% to give a concentration of 100 microgram/ml. 100 microgram (1 ml) boluses can be given. Phenylephrine can cause maternal bradycardia that may require treatment with glycopyrrolate, ephedrine or atropine. Occasionally a patient’s blood pressure may not respond well to phenylephrine and ephedrine in 6mg increments may be helpful in this situation. Combining phenylephrine and ephedrine does not increase fetal acidosis6,7.
Women with pre‐eclampsia develop less hypotension after spinal anaesthesia than healthy women. Abrupt decreases in blood pressure are undesirable because of the potential for decreased uteroplacental blood flow. A prophylactic vasopressor infusion may not be required but, if used, should be started at a lower rate than for healthy women4. Ephedrine and phenylephrine can be given in severe pre-eclampsia to treat hypotension after spinal block8. Careful dose titration should be used when giving vasopressors in this group of patients.