pulmonary disorders
Measurement of Gas Exchange
Pulse Oximetry
Transcutaneous pulse oximetry estimates oxygen saturation (SpO2) of capillary blood based on the absorption of light from light-emitting diodes positioned in a finger clip or adhesive strip probe. The estimates are generally very accurate and correlate to within 5% of measured arterial oxygen saturation (SaO2). Results may be less accurate in patients with Highly pigmented skin Arrhythmias Hypotension Profound systemic vasoconstriction Pulse oximetry results are also less accurate in patients wearing nail polish. Pulse oximetry is able to detect only oxyhemoglobin or reduced hemoglobin but not other types of hemoglobin (eg, carboxyhemoglobin, methemoglobin); those types are assumed to be oxyhemoglobin and falsely elevate the SpO2 measurement. 