Validity of pulse oximetry during ventilator weaning of adult open heart surgery patients

The aims of this research were (a) to evaluate the validity of pulse oximetry as a criterion of tissue oxygenation for nurses to use during ventilator weaning in adult open heart surgery patients, (b) determine which measure of tissue oxygenation (via pulse oximeter or arterial blood gas analyzer) is most valid to use during three phases of ventilator weaning. Little research has been done on ventilator weaning, even though it is an established nursing procedure in critical care units. Measurements of oxygen saturation via pulse oximetry are an established standard of care when weaning ventilator supported patients, yet no research-based data are available to support its widespread use. A descriptive, repeated-measures design was used to assess the agreement of blood oxygen saturation measured by three instruments during three phases of ventilator weaning. Study participants were 16 fair-skinned adults who had open heart surgery. Graphical analyses were computed to assess the agreement between the three blood oxygen saturations. Analyses of data suggest that mean pulse oximeter and mean arterial blood gas oxygen saturations differed by less than 1.7% during ventilator weaning. When mean oxygen saturations from the pulse oximeter and arterial blood gas analyzer were compared with the mean hemoximeter oxygen saturation both exceeded the 'standard' (hemoximeter) by more than 5%, making the measured agreement between them unacceptable. The findings of this study suggest that oxygen saturation measured via pulse oximetry is accurate when compared with data obtained via an arterial blood gas analyzer. However, it is not recommended that nurses abandon the practice of performing arterial blood gases to verify whether or not low SpO2 values measured by pulse oximeter are accurate. Wide fluctuations in Po2 can occur without corresponding changes in SpO2. One statistically significant relationship was found between SpO2 and Po2 r(16) =.63. No significant association was found among pH, Pco2, and core body temperature with SpO2 during ventilator weaning.