Anesthetic Management of a Parturient with Superior Vena Cava Obstruction for Cesarean Section

A 35-yr-old woman (gravida 4 para 1) with SVC obstruction was referred for anesthetic assessment at 32 weeks’ gestation. Medical history included an above-knee amputation of the left leg 4 yr previously for a malignant schwannoma and metastatic lesions in the upper lobe of the left lung 2 years after the amputation. She was orthopnoeic and had distended neck veins, but air entry was normal in both lungs. Chest radiography showed a widened mediastinum with a mass taking up half the right hemithorax. Computed tomography also showed a mass in the paratracheal region that was compressing the SVC (fig. 1). Arterial blood gas while the patient was breathing room air showed a respiratory alkalosis with hypocapnia (p  H 7.58, partial pressure of carbon dioxide [Pco²]= 28.9 mmHg, partial pressure of oxygen [Po²]= 97.3 mmHg, bicarbonate [HCO³]= 27 mm, base excess = 6.9).

A course of radiotherapy was attempted to shrink the tumor, but after 3 cycles over 2 weeks, severe orthopnoea and hypoxia developed (p  H 7.38, Pco²= 30.9 mmHg, Po²= 48.0 mmHg, HCO³= 18.9, base excess =−5.4 with room air), and radiotherapy was discontinued. The patient was propped up and administered dexamethasone and 35% oxygen via  mask, which partially alleviated her symptoms. Because of the presence of metabolic acidosis, the decision was made to expedite the delivery of the neonate via  cesarean section.

An epidural anesthetic was planned, with the cardiothoracic surgeon standing by and the cardiopulmonary bypass pump readily accessible. Intravenous access was secured on the right foot and left hand. Baseline blood pressure, measured via  right radial artery cannulation was 140/90 mmHg, pulse was 120 beats/min, and pulse oximeter reading was 99% with 35% oxygen by mask. After insertion of the epidural catheter while the patient was in the sitting position and administration of 3 ml bupivacaine, 0.5%, she was laid supine with a head-up tilt of 30°. While establishing an adequate anesthetic level, the cardiothoracic surgeon prepared the left femoral vessels for immediate cannulation, if necessary. Fractionated boluses of 0.5% epidural bupivacaine to a total of 12 ml achieved a block to T4–T6. The cesarean section was uneventful and resulted in the delivery of a 2-kg girl infant, with an Apgar score of 9/10 at 1 and 5 min. Blood pressure was well maintained with a minimum of 90/55 mmHg and titration of ephedrine boluses was necessary to a total of 47.5 mg, with infusion of 500 ml Ringer’s lactate and 500 ml Gelafundin (a polymerasate of degraded succinylated gelatin, with mean molecular weight 35,000; B. Braun Pharmacentical Industries, Penang, Malaysia).

Postoperatively, the patient was administered 5,000 U subcutaneous heparin twice daily for 5 days. Respiratory distress improved, and by the second postoperative day arterial blood gas was normal for breathing room air. The patient was discharged on the sixth postoperative day and was last seen 6 months later, by which time she had undergone a sixth course of chemotherapy; she is symptom free.

Numerous reports stress the high mortality and morbidity 2–6associated with general anesthesia in patients with SVC syndrome. In part, this is caused by partial or total airway obstruction and inability to perform ventilation for the patient. 7With this and the well-being of the fetus in mind, we considered regional anesthesia to be a better alternative for this patient. Spinal anesthesia was ruled out because rapid sympathectomy and hemodynamic decompensation might have been disastrous because of obstructed venous return from the upper extremities, caused by the mediastinal mass and from the lower extremities by the gravid uterus. Continuous spinal anesthesia and combined spinal–epidural anesthesia were rejected because little is known about the dynamics of intrathecal distribution of local anesthetics in patients with SVC and infererior vena cava obstruction. Epidural anesthesia was thought to be the best option. The lower-than-usual dose of bupivacaine necessary to achieve a level of T4 was not unexpected. The decrease in blood pressure was managed successfully by titration of ephedrine and fluids.

In the event of an unsuccessful epidural, we planned to administer a general anesthetic via  rapid-sequence induction with femoral–femoral access to institute immediate cardiopulmonary bypass if intubation or ventilation were not possible. 5,8Venous return to the heart from the upper limbs may be compromised in SVC syndrome. Hence, intravenous drugs and fluids were administered through the intravenous cannula on the right foot. The cannula in the left hand was placed if inferior vena cava obstruction before delivery prevented venous return from the lower limbs. Intraarterial monitoring was essential to immediately detect and manage changes in blood pressure. Central venous pressure monitoring was not attempted because it would have been unreliable in the presence of SVC obstruction and would not have altered our choice of management.

We initially hoped to rely on options such as chemotherapy, radiotherapy, and steroid therapy to shrink the tumor mass 2,9,10before surgery to decrease the anesthetic risk of respiratory obstruction or cardiovascular decompensation. With respect to the effects on the fetus, radiotherapy was considered to be safer than chemotherapy. Unfortunately malignant schwannomas are not sensitive to radiotherapy or chemotherapy, and this option was not helpful in this particular case. In summary, the anesthetic management of a parturient with SVC obstruction is presented herein, and the variousmethods to produce a safe outcome for parturient and fetus were discussed.

The authors thank B. J. Abdullah, F.R.C.R., Department of Radiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia, for interpreting the computed tomography scan.