Lagging of pulse-ox

Q: Pulse-oximetry reading (finger probe) lags behind the central arterial circulation?

A) True
B) False


Answer: True (A)

Although sound very simple and obvious but this is a critical point in intensive care unit's patients where other clinical signs of deterioration precede before desaturation. This lagging of pulse-ox desaturation may put an unexperienced house-staff under false sense of comfort and golden moment of intervention may get lost.



References:

1. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med 2012; 59:165.

2. Ding ZN, Shibata K, Yamamoto K, et al. Decreased circulation time in the upper limb reduces the lag time of the finger pulse oximeter response. Can J Anaesth 1992; 39:87.