Respiratory failure in the paediatric population differs from the adult population by the presence of some discrete age-related groups of differentials, with specific focus on consequences of prematurity and congenital disease. There are also physiological and anatomical differences which predispose the children to respiratory failure. These can be summarised as "functional and structural immaturity", and describe a respiratory system which is poorly adapted to extrauterine life, reflecting the basic biological disadvantages of having a complex brain (as our maturation process necessarily takes much longer than that of a lamprey).
Previous SAQs discussing respiratory failure were heavy on the bronchiolitis:
- Question 11 from the first paper of 2016 (all about bronchiolitis)
- Question 7 from the second paper of 2011 (a list of differentials, risk factors, normal physiology... and bronchiolitis)
- Question 6 from the first paper of 2009 (bronchiolitis)
So, it's all basically bronchiolitis and if you study bronchiolitis you're reasonably well set up for these sorts of questions. The only exception was Question 7 from the second paper of 2011, which was done reasonably well (pass rate 58%). The college wanted to know basic respiratory parameters (eg. resp rate) which would be normal for a given age group, as well as clinical features of respiratory distress, differential diagnosis of respiratory failure and factors which predispose neonates to this sort of collapse. In this chapter, these and other generic respiratory failure issues will be discussed, whereas bronchiolitis seems important enough to deserve its own section.
Unfortunately, there does not seem to be any convenient single resource to answer SAQs like Question 7, and even Oh's manual (Chapter 105 by Tavey Dorofaeff and Kevin Plumpton) is somewhat uninformative. The most useful references for the answers below were from the APLS handbook (I have the 4th edition) and the excellent article by Jürg Hammer ("Acute respiratory failure in children", 2013). Unfortunately it is not available as free full text.
Differential diagnosis of respiratory failure according to age group
This borrows heavily from the Oh's manual Blue Box number 105.1, on page 1086 (7th ed).
Normal range of respiratory variables
The following table is from the Royal Children's Hospital In Melbourne, where it is available as a lanyard. If it's good enough to hang on their necks, its good enough for the CICM SAQs.
|Age||Weight (kg)||Systolic BP (mmHg)||HR (BPM)||Resp rate|
Clinical features of respiratory distress
Question 7 from the second paper of 2011 lists the following clinical signs:
- Distortion of the chest wall (sternal and rib retraction, recession of intercostal, subcostal and suprasternal spaces) Accept alternative terminology
- Lethargy, listlessness, decreased level of consciousness
To this, one might add:
- Expiratory grunting
- Nasal flaring
- Failure to feed
Factors which predispose infants to respiratory failure
This table was constructed mainly using Hammer's excellent review article, "Acute respiratory failure in children" (2013)
|Structural immaturity of the respiratory system||
|Perinatal events or congential catastrophes||
|Post-uterine gas transport||
|Immature immune system and increased susceptibility ro respiratory infection||