[Pulse oximetry in the dialysis room].

The use of pulse oximetry can improve the management of critical events and daily clinical problems in a haemodialysis unit. Blood oxygen saturation using pulse oximetry (SpO2), the so-called 'fifth vital sign', can be determined together with noninvasive blood pressure measurement, before haemodialysis treatment or when, during treatment, a patient's condition suddenly worsens. The pulse oximeter provides useful information on pulse rate and on heart rhythm. It can be considered a diagnostic first step for dyspnoea because normal-high values rule out interstitial pulmonary fluid. It is also a useful screening for blood gas analysis, providing confirmation of arterial blood from an arteriovenous fistula sample. It can indicate when oxygen therapy should be initiated and provides monitoring. Finally, it can be used to explore pulse blood flow distal to the arteriovenous fistula.