1Academic Unit of Anaesthesia, Leeds General Infirmary, Leeds LS1 3EX, UK. 2Obstetric Anaesthesia, St Jamess University Hospital, Leeds LS9 7TF, UK*Corresponding author
Accepted for publication: July 20, 2000
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Abstract |
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Br J Anaesth 2000; 85: 91113
Keywords: anaesthesia, obstetric; children, cancer; anaesthetic techniques, epidural
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Introduction |
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Case 1 |
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From the history and examination in the clinic, it was felt that reduced cardiac reserve posed the greatest anaesthetic problem, and that technical difficulty with regional block arising from scoliosis was a secondary concern. No respiratory problems were anticipated, and further investigations were not thought to be necessary. The plan agreed upon for anaesthesia was to use an incremental subarachnoid technique, with invasive arterial monitoring but without a pulmonary artery flotation catheter.
Before operation, a 20-gauge cannula was inserted into the left radial artery, and a 16-gauge i.v. cannula was inserted into a forearm vein. An infusion of Gelofusine (B. Braun Medical Ltd, Aylesbury, UK) 500 ml was commenced. Further monitoring included ECG and pulse oximetry. In the sitting position, a 26-gauge Quincke spinal needle was inserted with difficulty into the L3/4 interspace. A 32-gauge catheter (TFX Medical, Lurgan, N. Ireland) was then inserted and the needle removed. Two centimetres of catheter was placed in the subarachnoid space. Initially, 0.5% w/v hyperbaric bupivacaine 1 ml and diamorphine 0.4 mg were injected whilst the patient was sitting. A further 500 ml of Gelofusine containing ephedrine 30 mg was commenced. The patient was then moved into a tilted left supine position. After 10 min, plain bupivacaine 2.5 mg was injected. Sensation was blocked up to T6 on the right and T4 on the left. Caesarean section was performed without incident. Transient hypotension (systolic pressure of 60 mm Hg) occurred on administration of a test dose of Syntocinon 1 IU, and no further oxytocic was given. A live female baby weighing 2 kg was delivered. Apgar scores at 1 and 5 min were 8 and 9 respectively, and the umbilical arterial pH was 7.36.
For postoperative analgesia, the patient received diclofenac 100 mg per rectum, and thereafter up to 150 mg orally per day, and paracetamol 1000 mg/codeine 60 mg as required to a maximum of six doses per day. The intrathecal catheter was removed in the recovery ward 2 h after operation. We continued invasive monitoring for 24 h after delivery and the patient was stable throughout this period. Blood loss at delivery was estimated at 500 ml, but the haemoglobin had decreased to 8.1 g dl1 on the first postoperative day and 3 units of blood was transfused. The patient was seen by an anaesthetist for three consecutive days to identify complications of regional block. No such complications were apparent. The mother and baby were discharged home after 5 days. Antihypertensive medication was continued on discharge.
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Case 2 |
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On examination she was of short stature (147 cm, 4 ft 11 inches) and had mandibular hypoplasia, which was considered likely to cause difficulty with intubation (Mallampati grade 2). There was little opportunity for further investigation. Cardiomyopathy secondary to an unknown anthracycline had been diagnosed previously and mid-trimester echocardiography demonstrated an ejection fraction of 60% and fractional shortening of 23%. Her medical history included fractured lumbar spine, for which no details were available. She was taking thyroxine because treatment had resulted in thyroid hypoplasia.
An incremental subarachnoid technique was chosen. In case regional anaesthesia was not successful, facilities for awake fibre-optic intubation were available. Before the block, monitoring with ECG, non-invasive arterial blood pressure and pulse oximeter were established. An i.v. cannula was placed in a forearm vein and Gelofusine 500 ml was given. In the absence of signs and symptoms of heart failure, invasive monitoring was considered unnecessary. Aseptic techniques were used, including gown, hat and mask. The skin was prepared with alcohol solution. We used a needle-through-needle technique with a Spinocath kit (B. Braun Medical, Melsungen, Germany). An 18-gauge Tuohy needle was placed in the epidural space and a 24-gauge catheter was threaded over a 29-gauge Quincke spinal needle passed intrathecally. Both needles were then withdrawn. An i.v. infusion of ephedrine 30 mg in Gelofusine 500 ml was begun with the first intrathecal injection. Three increments of 0.5% w/v hyperbaric bupivacaine were given (10 mg in total), together with 0.5% w/v plain bupivacaine 4 mg, and diamorphine 0.4 mg, without achieving a satisfactory block. At this point it was decided that the tip of the catheter might be positioned in a caudad direction and the catheter was withdrawn 2 cm. Hyperbaric bupivacaine 0.5% w/v 2.5 mg and 0.5% w/v plain bupivacaine 5 mg were then given, producing excellent anaesthesia with abolition of sensation bilaterally to T5. There was no haemodynamic disturbance, and the patient was stable throughout. A female baby was delivered, and the umbilical arterial pH was 7.28. Syntocinon 10 units was given slowly via the i.v. infusion on delivery, without detectable hypotension. Prophylactic cefuroxime 750 mg and metronidazole 500 mg were given i.v. in the operating theatre and continued orally for 5 days. Postoperative analgesia consisted of diclofenac and paracetamol/codeine. The estimated blood loss at delivery was 700 ml. The intrathecal catheter was removed in the recovery ward. The next day, haemoglobin was recorded as 9.8 g dl1 and 3 units of blood was transfused. An anaesthetist visited the patient for 3 days to identify complications of regional blockade. The mother and baby were discharged home after 5 days.
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Discussion |
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Anthracycline cardiotoxicity
Anthracyclines are a family of cytotoxic antibiotics. Anthracycline cardiomyopathy is a dose-dependent complication of therapy with doxorubicin and daunorubicin, which damages myocytes and impairs cardiac growth.2 If given in childhood, normal cardiac growth is impaired, leading to permanent cardiac dysfunction. The toxicity has been attributed to the production of free radicals. The incidence of cardiomyopathy after chemotherapy is unknown, and whether a safe dose exists has not been clarified. Changes are irreversible and are characterized by a poorly compliant myocardium3 that is likely to respond poorly to changes in preload and afterload. Diagnosis is made clinically, using echocardiography or cardiac catheterization, but may be confirmed histologically, showing hypertrophy and fibrosis of myocytes.3 Both our patients had impairment of left ventricular function, but one woman was symptomatic with breathlessness, indicating a degree of cardiac failure. Her limited cardiac reserve presumably accounted for the hypotension after administration of 1 unit of Syntocinon. We did not think it advisable to give a further dose. Our second patient, despite a fractional shortening of 23%, was asymptomatic and tolerated Syntocinon well. Clinical assessment correctly identified which woman posed the greater risk. The long-term prognosis of this condition may be poor, and transplantation has been required.4
Scoliosis and short stature
Scoliosis can be a cause of short stature. In our first case, the scoliosis was presumed to be secondary to radiation-induced hip deformity. The spine may also be affected during the irradiation of midline tumours,5 and deformity, white matter injury, osteoporosis and epidural space scarring has been documented.5 Norris recommended one dose of single-shot intrathecal local anaesthetic for regional block, assuming normal anatomy, but of the 50 women included in that study only one was less than 150 cm tall.6 Scoliosis and short stature can cause uncertainty about the dose of intrathecal local anaesthetic required. Our solution to potential problems within the epidural space is to use an intrathecal approach, and because of uncertainties over dose we titrated the local anaesthetic through an indwelling catheter. This had the added advantage of a slow onset of block, avoiding cardiovascular upset.7 An additional factor in our choice was that we have significant experience with Caesarean delivery in scoliotics using continuous intrathecal anaesthesia.8
Oxytocics
Oxytocics are used to provide uterine contraction and haemostasis after delivery. Two drugs are commonly used for this purpose: ergometrine and Syntocinon, singly or in combination. Ergometrine, an ergotamine alkaloid, is a powerful oxytocic but is known to raise systemic vascular resistance significantly and increase afterload.9 Syntocinon, a synthetic form of the naturally occurring oxytocin, has greater cardiac stability, but is known to cause hypotension with bolus administration.10 The mechanism for this is debatable. Possible causes are a reduction in venous pressure, a decrease in vascular resistance, and negative inotropy, or a combination of these.10 Death at Caesarean section has occurred after bolus administration of Syntocinon in a woman with congenital heart disease.11 Our experience demonstrates that even minute doses of Syntocinon can cause worrying hypotension in the presence of poor myocardial function. It has been suggested that slow infusion of Syntocinon may reduce the incidence of hypotension.9 Cardiac output monitoring is justified when effects are predicted to be severe.
Survivors of childhood cancers will present with increasing frequency for obstetric anaesthesia both to regional centres and to district general hospitals. It is likely that these women will have abnormalities affecting anaesthesia and a management plan should be made in the antenatal period. Adult survivors with lifelong cardiac impairment secondary to anthracyclines are an emerging problem. The first exposure of young adult cancer survivors to anaesthesia may occur with their first pregnancy, and the obstetric anaesthetist may be the first to test cardiac performance and to deal with the sequelae of their treatments.
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References |
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11 Department of Health. Report on confidential enquiries into maternal deaths in the United Kingdom 19791981. London: HMSO, 1986