Continuous Oxygen Saturation Monitoring during Cardiac Catheterization in Adults
Cardiac catheterization has been associated with a variety of complications, including arrhythmias, myocardial infarction, hypotension, and acute pulmonary edema. Hypoxemia may occur during cardiac catheterization and could contribute to morbidity, as well as potentially alter physiologic parameters measured at catheterization. We know of only two published studies in which arterial hemoglobin oxygen saturation (SaOJ was continuously monitored during cardiac catheterization.* Both of those investigations were conducted on pediatric patients and were performed to determine the reliability of noninvasive Sa02 monitors. Using pulse oximetry, we examined the continuous beat-to-beat changes in Sa02 in an adult population during cardiac catheterization. Measurements of Sa02 by noninvasive pulse oximetry have been shown to be accurate over a wide range of saturations when compared to in vitro blood measurements of Sa02 using a spectrophotometric oximeter (CO-Oximeter).
Materials and Methods
After receiving approval from our institutional Clinical Investigation Committee, we studied 29 patients undergoing cardiac catheterization. Indications for catheterization included the diagnosis of coronary artery (N = 12) or valvular heart disease (N = 4), assessment of ventricular function (N = 4), and percutaneous transluminal coronary angioplasty (N = 9). With the exception of one patient, who was catheterized emergently for unstable angina, all procedures were scheduled electively. Patients were excluded if they were receiving supplemental oxygen upon arrival at the catheterization laboratory or prior to the start of the procedure.
The Sa02 was continuously monitored throughout the catheterization by means of a pulse oximeter (Nellcor N-100) and was recorded at four-second intervals (Nellcor N-9000 recorder). The pulse oximeters probe was placed on the patients left index finger, with the hand at heart level, as soon as the patient was transferred to the catheterization table. Baseline measurements of Sa02 were recorded after the patient had been lying supine on the catheterization table for two to five minutes prior to any intervention. The pulse oximeters display was continuously monitored during the procedure to assure accurate tracking of arterial pulsations. Any change in Sa02 while the pulse oximeter was not tracking arterial pulsations correctly, as determined by the oximeters display of pulse strength and pulse rate when compared to a simultaneous electrocardiogram, was not included.