Investigations

• pulse oximetry - but beware! ^c

Why?

Pulse oximetry is unhelpful in excluding hypoxia

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
healthy children with sickle cell disease c (pre-test probability: 37%)	hypoxia (pulse oximetry: SaO2 < 93%)	pulse oximetry: SaO2 < 93%	- (1.3 to infinity)	100%	0.71 (0.45 to 1.1)	29%