SvO2 Values Research Articles

Continuous Monitoring of Mixed Venous Oxygen Saturation in Critically Ill Patients

A new pulmonary artery balloon flow-directed catheter combines a fiberoptic photometric system for continuous display of mixed venous blood oxygen saturation (SvO2) with the capacity for hemodynamic measurements including thermodilution cardiac output estimation. This oximetry system was studied to determine its accuracy, reliability, and usefulness in the surgical intensive care unit (ICU). Twenty-two catheters were tested, but only 17 were successfully placed in 16 patients. There were technical problems associated with 10 catheters and on six occasions these necessitated the use of another catheter. The catheter values for SvO2 were closely related (r = 0.9516) to those obtained from a laboratory Co-oximeter. Continuous monitoring of SvO2 is accurate and valuable as a warning system for deterioration in cardiopulmonary function and as an indicator of the effects of various therapeutic maneuvers in critically ill patients.

The Lack of Effect of Variable Blood Withdrawal Rates on the Measurement of Mixed Venous Oxygen Saturation

In a study of 12 critically ill patients, values for mixed venous oxygen saturation (SVO2) were measured from samples of pulmonary arterial blood drawn at five rates of withdrawal (1, 3, 10, 20, and 30 ml/min). Samples were drawn from properly placed pulmonary arterial catheters with the balloon deflated. Physiologic stability was documented at the beginning and end of the sampling period in all but one patient. Results in each patient demonstrated a close grouping of values for SVO2 obtained at the five rates of withdrawal (largest standard deviation, 1.9 percent). Evaluations by paired t-test comparing all rates of withdrawal with the slowest rate (1 ml/min) showed no significant differences. The rate of withdrawal of the sample is not associated with significant errors in SVO2 when samples are drawn from a properly positioned pulmonary arterial catheter.

Blood oxygen transport and metabolism of the confined lugworm Arenicola marina (L.).

Oxygen consumption (MO2), haemoglobin oxygen saturation level (SVO2) and pH (pHv) in prebranchial blood were measured in lugworms experimentally confined in sea water at 15 degrees C. Total blood flow through the gills (Vb) was estimated. For sea water oxygen partial pressure (PwO2) between 120 and 150 Torr MO2, SVO2 and Vb were high and nearly constant. For PwO2 less than 120 Torr, Vb fell quickly, MO2 progressively dropped, and metabolism remained aerobic at the expense of the prebrancial blood oxygen store. For PwO2 less than 50 Torr, Vb and SvO2 values were extremely low, and the low pHv and the modified buffer power of the surrounding sea water showed that anaerobic metabolism was occurring. Changes in respiratory gas exchanges and metabolism during the tidal cycle are deduced from the comparison of these results with data obtained in the field.