Which of the following would be the LEAST appropriate I:E (inspiratory to expiratory) ratio when ventilating a child who is now intubated secondary to status asthmaticus?
a) 1:1
b) 1:2
c) 1:3
d) 1:4
e) They are equally appropriate
Answer a.
Children who have severe asthma or who are in status asthmaticus will have prolonged expiration and are at risk of developing air trapping and auto- PEEP if they are ventilated with an inappropriate I:E ratio (i.e. not given enough time to exhale). As such, one should choose a long expiratory time, usually at least 1:3. Using a 1:1 I:E ratio is the least appropriate of the options.