Acid aspiration prophylaxis in 288 obstetric anaesthetic departments in the United Kingdom. The choice of drugs for acid aspiration prophylaxis in 288 obstetric anaesthetic departments in the United Kingdom was determined by questionnaire. The results are compared with a similar survey of anaesthetic departments 5 years ago. The prescription of sodium citrate and the H2 receptor antagonist ranitidine has superseded that of Mist. magnesium trisilicate. 