Scoline apnoea and pregnancy: SICU experiences

Background: Suxamethonium chloride (scoline) is a short acting depolarizing muscle relaxant; it was discovered early in the nineteenth century but not used in clinical practice until 1951.(1) Scoline became a popular muscle relaxant due to its rapid onset of action, quick metabolism and hence shorter duration of action. It is metabolized by cholinesterase. Scoline apnoea was described within a few years of clinical use of Suxamethonium due to inherited or acquired deficiency of the cholinesterase enzyme resulting in prolonged muscle relaxation.(2) Now scoline is used in prehospital and emergency intubating conditions, in pregnancy fetal distress or cord prolapse due to obvious advantages in these circumstances.(3,4,5) The aim of our study was to investigate the trends and incidence of scoline apnoea in pregnant patients. Patients and methods: All patients admitted with scoline apnoea during pregnancy in the surgical intensive care unit of a tertiary healthcare facility were included retrospectively in our study. Patients demographic data, duration of apnoea and intubation, intensive care unit stay and trends of scoline apnoea were recorded. Results: A total of 32 pregnant patients post-lower segment caesarean section were admitted to the surgical intensive care unit during the study period. The indications for general anaesthesia in the majority of patients were obstetrical emergencies (n = 23, 71.87%), refused regional anaesthesia (n = 7, 21.87%), and required general anaesthesia after the regional anaesthesia (n = 2, 6.25%) patients. Twenty-nine (90.62%) patients received premedication with metoclopramide and sodium citrate (Table 1a). Thirty (93.75%) patients received reversal combination of neostigmine and atropine. Four (12.50%) patients received fresh frozen plasma (Table 1a). The mean age of the patients was 31.7 ± 6.4 years old (minimal age was 25 years), all patients belonged to ASA class 1 and the mean duration of apnoea time was 4 ± 2.5 hours. The duration of intubation was 6 ± 4.5 hours and the length of surgical intensive care stay was 1.2 ± 0.7 days (Table 1b). As shown in Figure 1a, the majority of patients were found to belong to the age group of 31 to 35 years (n = 12, 37.5%), followed by 9 (28.12%) patients in the age group of 26 to 30 years. It was also found that the Qatari locals and Egyptians formed the majority nationality (n = 12, 37.5% and n = 7, 21.87%) of patients (Figure 1b). The overall Arab patient population had a higher incidence of scoline apnoea compared to the Asian group of patients. All patients were found to have cholinesterase levels below 3500 units/litre (normal range varies from 5400 to 13,200 units/litres), which is less than 70% of the normal value (Figure 2a). There was a decreasing trend of scoline apnoea patients in recent years. From 2013 to 2016, there were no patients admitted to SICU with scoline apnoea and in 2017, only one patient with scoline apnoea was admitted (Figure 2b). Conclusion: Scoline apnoea incidence and trend in our parturient population is decreasing. The majority of our patients received premedication and reversal medication which decreases the cholinesterase levels. The decreasing trend may be attributable to increased regional anaesthesia practice and frequent use of rocuronium.