Combined spinal epidural anaesthesia in a case of primigravida with coarctation of aorta with severe hypertension for elective lower segment caesarean section

Sir,

Coarctation of aorta accounts for 6% of congenital heart lesions. An uncorrected coarctation of aorta during pregnancy places the patient at risk for left ventricular failure (LVF), aortic rupture/dissection and endocarditis, and it represents a fixed obstruction to left ventricular ejection.[1]

A 25-year-old female term gravida was admitted to the Department of Obstetrics with asymptomatic coarctation of aorta. Her pulse rate (PR) was 100 bpm and its volume was high in the right radial artery. Her blood pressure (BP) was 180/80 mmHg in the right upper limb, 130/90 mmHg in the left upper limb and 130/80 mmHg in the left lower limb. An ejection systolic murmur was heard in the left 5^th intercostal space and pansystolic murmur in the right second intercostal space. Electrocardiogram was suggestive of left axis deviation. Echocardiography showed mild mitral regurgitation, and juxtraductal coarctation of aorta with continuous monophasic flow. She was on oral amlodipine 10 mg, metoprolol 100 mg and prazosin 2.5 mg once daily which were continued preoperatively.

In the operation theatre, non-invasive BP monitoring and pulse oximetry were initiated. Two large bore intravenous lines were secured on both upper limbs. Combined spinal epidural anaesthesia (CSEA) with volume expansion was planned. Epidural space was identified at L2–L3 interspace and a 20 G epidural catheter was inserted and fixed at 8 cm. Injection lignocaine 2% 1 ml was given as a test dose. At L3–L4 interspace, 1 ml of hyperbaric 0.5% bupivacaine with 10 μg fentanyl was injected intrathecally. The patient was placed in the supine position with a wedge under her right buttock. Sensory level achieved was T9. After an epidural dose of 3 ml 2% lignocaine, a sensory blockade up to T6 was achieved.[2,3]

Intraoperatively, BP in the right upper limb was maintained between 160/80 mmHg and 150/60 mmHg and in the right lower limb between 120/70 and 100/60 mmHg. PR was maintained between 80 and 90 beats/min. Injection ephedrine 12 mg was given during the first 15 min after administering spinal anaesthesia. Fluids given included 500 ml tetrastarch, 500 ml dextrose normal saline and 500 ml ringer lactate solution. The surgery was uneventful.

The three main goals of anaesthesia include maintenance of adequate intravascular volume, prevent decrease in PR and BP so as to avoid compromise on the maternal myocardium and placental blood flow and finally to provide adequate perioperative pain relief to avoid stress to the patient's cardiovascular system.[4]

Using epidural volume expansion in CSEA, these goals were successfully achieved.[5,6] The resultant substantial reduction in local anaesthetic dose produced an effective block, decreased the side effects and caused less motor blockade. The haemodynamic stability was meticulously taken care of.

In conclusion, CSEA has several advantages over general anaesthesia. Because a titrated dose of local anaesthetic is given, CSEA confers better haemodynamic stability. It overcomes the disadvantages of general anaesthesia such as a surge in HR and BP during intubation which may lead to aortic rupture, dissection or LVF. In addition, the opioids administered systemically may lead to respiratory depression in both parturient and neonate.[2]

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