Introduction

Registry data from the UK and US have found that adverse events occur during approximately 4% of procedural sedations performed in the ED [3,4].

Most are minor, occurring most frequently when the patient undergoing sedation has a high ASA classification or during the deeper levels of sedation.

Table 1: American Society of Anaesthesiologists classification system [3,4]
ASA classification	Health status of patient
I	A normal healthy patient
II	A patient with mild systemic disease
III	A patient with severe systemic disease
IV	A patient with severe systemic disease that is a constant threat to life
V	A moribund patient who is not expected to survive without the operation
VI	A declared brain-dead patient whose organs are being removed for donor purposes