| Description |
This research examined the use of the Oximeter Opticath System's unique monitoring capabilities for pulmonary capillary wedge position confirmation. The system's ability to monitor oxygen saturation and reflected light characteristics was evaluated in 13 subjects during 23 catheter wedge position measurements. Oximeter oxygen saturation values were compared with laboratory-determined values while the catheter was in the pulmonary artery and pulmonary capillary wedge positions. The oximeter and laboratory values were found to correlate positively in both the pulmonary artery and pulmonary capillary wedge positions (n = .50 and .82 respectively). The errors between the oximeter and the laboratory oxygen saturation values in the two catheter positions did not differ significantly from each other. The difference between the oximeter oxygen saturation values in the pulmonary artery and in the pulmonary capillary wedge positions was also evaluated. As was expected, the mean wedge oxygen saturation value was significantly higher than the man pulmonary artery oxygen saturation value. Twenty-three samples aspirated from the wedge position were evaluated by the laboratory for capillary blood gas criteria. Seventy-eight percent (n = 18) of the wedge samples met capillary blood gas criteria positively confirming the wedge positions. Seventeen (94%) of the samples met the highly oxygenated (greater or equal to 90% saturated) criterion. The oximeter accurately measured oxygen saturation in all but one of the confirmed samples. Of the remaining 22% (n = 5) of wedge samples which did not meet capillary blood gas criteria, one oximeter value was greater than 90% saturated when the corresponding laboratory value was less than 90% saturated. Thus, of the 26 wedge oximeter oxygen saturation values, three would have resulted in clinically significant errors had the oximeter values been used for evaluating the wedge position in lieu of laboratory values. The oximeter system's "intensity signal," which evaluates the characteristics of the reflected light, was evaluated for quantity (signal range on the recorder paper percent scale) and pulsatile quality (peak-to-peak height) while the catheter was in the pulmonary artery and pulmonary capillary wedge positions. All signals evaluated normal while the catheter was in the pulmonary artery position. With catheter wedging, 83% (n = 19) if the signals within the normal range of 74% (n = 17) became damped (less than the normal peak-to-peak height). The mean signal heights between pulmonary artery and pulmonary capillary wedge catheter positions differed significantly. The study results support the use of the Oximeter Opticath System for pulmonary capillary wedge position confirmation. The majority of wedge positions were confirmed by meeting capillary blood gas criteria, and the majority of confirmed wedge positions yielded blood samples which met the highly oxygenated criterion. The oximeter was found to be as accurate for evaluating wedge position oxygen saturations as pulmonary artery oxygen saturations. Observing the intensity signal can be used as an additional criterion for identifying the wedge position. Characteristically, the signal changes from normal to damped, indicating a reduction in pulsatile blood flow past the catheter tip. |
