Audit of the impact of magnesium sulphate on the management of severe pre-eclampsia in a London university hospital

Abstract

Hypertensive disorders of pregnancy remain a significant cause of maternal mortality and morbidity. We describe the impact of the introduction of a regional protocol (including the use of magnesium sulphate on the morbidity of women with severe pre-eclampsia attending an inner London university hospital. A retrospective analysis was performed of all patients treated with magnesium sulphate (MgSO4) from October 1995-September 1996. Thirty-five patients were identified from the labour ward and intensive care unit (ICU) records as having been potentially treated with MgSO4. Of these, 30 sets of notes were available for analysis and 22 women were identified as having received MgSO4. Treatment consisted of 4 g MgSO4 given intravenously (i.v.) over 20 min followed by an infusion of 2 g per hour until 24 h post-delivery as per the protocol written by Robson et al.[1] Plasma levels were not monitored and the women were reiewed hourly to review respiratory rate and the presence of deep tendon reflexes. During this period 21 obstetric patients were admitted to the ICU (seven with hypertensive disease). Twenty-two women were treated with MgSO4 during this audit of which 50% were of African origin (21% in the maternity population). Their mean highest blood pressure was 175/111 (180/95-220/120) mmHg with 14 women having >three pluses of proteinuria. Nine women developed thrombocytopenia (100 × 109 L), the mean urate was 0.436 mmol L−1. Five women were admitted to the ICU (two renal complications, two haematological and one for routine observations). Three women had to have their MgSO4 stopped for side effects (one was flushed, one was drowsy and one had a decreased respiratory rate though her Mg level was in the therapeutic range). There were no eclamptic fits after starting treatment. In comparison with a previous audit [2] (during which time Phenytoin was used) the total number of ICU admissions decreased (23 per annum in this study as compared with 29 per annum in the previous one); this reduction is almost entirely accounted for by the reduction in admissions for hypertensive disorders. Best practice for the management of severe pre-eclampsia includes both the use of regionally agreed protocols and the use of MgSO4 as anticonvulsant of choice, although its use prophylactically is still controversial. At this hospital we have shown that MgSO4 is safe to use with side effects being minor or quickly reversed (without the need to measure magnesium levels). We have shown a reduction in ICU admissions for hypertensive disease which is due to a number of factors including greater use of regional anaesthesia and improved nursing care on the labour ward. We feel that MgSO4 is safe to use for severe pre-eclampsia and the labour ward (or ideally an obstetric high-dependency unit) is a safe place to manage these patients.