VALUE OF PULSE OXIMETRY IN SCREENING FOR LONG-TERM OXYGEN-THERAPY REQUIREMENT

Pulse oximetry, combined with spirometry, was evaluated as a method of selecting chronic obstructive pulmonary disease (COPD) out-patients r equiring definitive arterial blood gas analysis for long-term oxygen t herapy (LTOT) assessment. A relatively high screening arterial oxygen saturation by pulse oximetry (SaO2) level was set, in order to maximiz e sensitivity. All 113 COPD out-patients attending the hospital clinic over a 6 month period were screened. Sixty had a forced expiratory vo lume in one second <1.5 l and 26 had an Sao2 less-than-or-equal-to 92% . These 26 underwent arterial blood ps analysis. Nine had an arterial oxygen tension <7.3 kPa all with an arterial carbon dioxide tension (P aco2) >6 kPa. A further eight had a PaO2 <8 kPa. This produced a sensi tivity of 100% and specificity of 69% for oximetry in the detection of Pao2 <7.3 kPa determined by direct arterial puncture and 100% and 86% respectively for detecting a Pao2 <8 kPa. Although the poor specifici ty of oximetry in the crucial Pao2 range makes it unsuitable, when use d alone, for prescription of LTOT, it may prove valuable in selecting patients who require further definitive arterial blood gas analysis.