Aust. N.Z.J. Obstet. Gynaec. (1979) 19: 59

Water Intoxication and Syntocinon Infusion T. R. Eggersl and J. R. Fliegner2 Royal Women's Hospital, Department of Obstetrics and Gynaecology, University of Melbourne, Melbolurne

Summary: A case of severe water intoxication with convulsion and prolonged coma, following the use of a high dose Syntocinon infusion is described. The pathogenesis and treatment of the condition are discussed.

The dangers of overstimulation of the myometrium by Syntocinon, resulting in tetanic uterine contractions, fetal hypoxia, or uterine rupture are well known. Water intoxication due to the suppression of diuresis was first reported by Liggins (1962) and Pittman (1963), and this complication occurring in pregnant patients receiving large doses of Syntocinon has been the subject of a small, but important group of papers in the recent literature (Leventhal et al., 1968; Lilien, 1968; Storch, 1970; Bilek et al., 1970; Morgan et al., 1977). Most case reports in the literature deal with the complication when high dose Syntocinon infusions are used for mid-trimester termination of pregnancy or for the induction of premature labour associated with fetaI death in utero. In the present report, antidiuresis and severe water intoxication with prolonged coma occurred with a high dose Syntocinon infusion at 24 weeks of gestation. CASE REPORT

The patient was a 25-year-old secundigravida, whose last normal menstrual period had begun in mid-December, 1977. She presented to her medical practitioner on June 8, 1978 at 24 weeks of gestation with spontaneous 1. Second Assistant. 2. First Assistant.

rupture of the membranes and passage of thick, dark liquor. The uterus was 16 weeks in size, and fetal death in utero was confirmed. An intravenous infusion of oxytocin in 5 % dextrose was commenced at 5 p.m. on June 8, and continued for 38 hours. Over this period, fluid intake was 4,650 ml (3,500 ml of 5% dextrose by intravenous infusion and 1,150 ml orally. Fluid output was 1,350 ml (urine 1,050 ml, vomitus 300 ml). A total of 295 units of Syntocinon were given. At 7 a.m. on June 10, the patient vomited once, had a single epilepiform convulsion and lost consciousness. Diazepam (10 mg) and frusemide (40 mg) were administered by intravenous injection. The patient remained normotensive and had no proteinuria over the treatment period. When examined an hour later after transfer to the Royal Women's Hospital, the patient was still unconscious, with only non-purposeful response to painful stimuli. The pupils were dilated and reacting, and the optic fundi were normal. There was no evidence of papilloedema. There was generalised hypertonia and hyper-reflexia. Plantar reflexes were flexor, the blood pressure was 120/80, pulse rate 96 per minute and temperature 36.5"C. The chest was clear and the uterine size was equivalent to that of a 16-week pregnancy. Speculum examination revealed an offensive, macerated fetus in the cervical 0s. Bacteriological

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smears were taken, and gentle traction enabled removal of fetus and placenta. Smear and culture revealed vast numbers of anaerobic organisms sensitive to penicillin. Serum sodium was 118 mmol/l, potassium 3.1 mmol/, bicarbonate 24 mmol/l, and urea 1.1 mmol/ 1. Serum osmolality was 247 mosmol/kg (normal range 278-305), urine osmolality 472 mosmol/kg (normal range 500-800). A diagnosis of fitting due to water intoxication was made, and 575 ml of 3N saline was given over 6 hours; maintenance fluid was then continued with Normosol M 1,000 ml per 24 hours. Intravenous chemotherapy with crystalline penicillin and sulphadimidine was given. In the 24 hours following admission there was a nett fluid loss of 2,400 ml. Although serum and urine biochemical normality had been attained within 8 hours of admission, consciousness to the level of verbal response was not resumed for 50 hours. At discharge on June 15, the patient appeared entirely normal. DISCUSSION

Although rarely associated with maternal death (Lilien, 1968), prolonged coma following convulsions attributable to water intoxication has been reported by a number of authors (Pittman, 1963; Silva et al., 1966; Josey et at., 1969; Pedlow, 1970; Morgan et al., 1970). The alteration in conscious state produced by cerebral oedema is attributed to hyponatraemia and a shift of fluid from the extracellular to the intracellular compartment (Plum et al., 1972; Laversen et a]., 1975). Dilution by the infused water (Silva et al., 1966), increased sodium excretion in the urine, and compartmental sodium shifts are responsible for the

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hyponatraemia (Gupta et al., 1972; Morgan et al., 1977). In the majority of reported cases water intoxication has occurred when large amounts of Syntocinon in electrolyte-free solutions have been given. Convulsions are unlikely unless the fluid input exceeds output by more than 3 litres in 24 hours, and is therefore uncommon following oxytocin induced labour at term. Cessation of oxytocin administration, combined with a slow infusion of mannitol and hypertonic saline expedites cerebral dehydration and restoration of normal blood chemistry. Although a return of normal cerebral function may be delayed for several weeks the ultimate prognosis is good.

References Bilek, W., and Dorr, P. (1970), Can. med. Assoc. J., 103: 379. Gupta, D. R., and Cohen, N. H. (1972), J. Amer. med. Assoc., 220: 681. Josey, W. E., Pinto, A. P., and Plant, R. F. (1969), Amer. J . Obstet. Gvnec., 104: 926. Laversen, N. H., and Birnbaum, S. J. (1975), Amer. J. Obstet. Gynec., 121: 2. Leventhal, J. M., and Reid, D. E. (1%8), Amer. I . Obstet. Gynec., 102: 310. Liggins, G . C. (1962), J . Obstet. Gynaec. Brit. Cwlth, 69: 277.

Licen, A. A. (1%8), Obstet. and Gynec., 32: 171. Morgan, D. B., and Kinvan, N. A., et al. (1977), Brit. J. Obstet. Gynaec., 84: 6. Pedlow, P. R. B. (1970), 1. Obster. Gynaec. Brit. Cwlth, 77: 1113. Pittman, J. G. (1963), New Engl. J . Med., 268: 481. Plum. F.. and Posner. J. B. (1972). in Diagnosis of Stuuor and Coma, 2nd Edn, Ed: F. ,A. Davh, F. A. Davis Company, Philadelphia. Silva, P., and Allan, M. S. (1966), Obstet. and Gynec., 27: c1-7

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Storch, A. S. (1970), Obstet. and Gynec., 37: 109.

Water intoxication and Syntocinon infusion.

Aust. N.Z.J. Obstet. Gynaec. (1979) 19: 59 Water Intoxication and Syntocinon Infusion T. R. Eggersl and J. R. Fliegner2 Royal Women's Hospital, Depar...
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