Jugular venous oximetry and oxygen tension during hypothermic cardiopulmonary bypass

Abstract

Introduction. In patients undergoing cardiopulmonary bypass (CPB), jugular bulb desaturation may be associated with postoperative neurocognitive dysfunction. We examined jugular bulb oximetry (SjvO2) and oxygen tension (PjvO2) in patients undergoing CPB with pH-stat perfusion management.Methods. Jugular bulb catheters were inserted in 12 patients undergoing hypothermic CPB for coronary artery bypass. Jugular bulb temperature was monitored continuously. Jugular venous blood was sampled at intervals during cooling, rewarming, and after bypass. SjvO2 was measured by cooximeter (AVOX System 4000). PjvO2 was measured by gas analyzer (Nova Stat Profile Ultra) and recorded both uncorrected at 37°C (stat) and temperature corrected (pH-stat).Results. SjvO2 decreased as jugular bulb temperature increased. However, only 2 patients demonstrated jugular bulb desaturation (<50%) during rewarming, both when jugular venous temperature exceeded 37.5°C. Desaturation during rewarming was not consistently associated with low PjvO2 values (<27 mm Hg). During cooling and hypothermia, PjvO2 (pH-stat values) were lower than PjvO2 (stat values) and may reflect a more accurate measure of brain oxygenation.Conclusions. During CPB, SjvO2 decreased as jugular bulb temperature increased, with desaturation noted during hypothermia. Therefore, brain oxygenation may be jeopardized in the presence of marked hypothermia. We also noted that, during cooling and hypothermia, PjvO2 measured with pH-stat technique was much lower than that measured with a stat technique. The significance of this finding requires further investigation. [1Croughwell N. Newman M. Blumenthal J. et al.Ann Thor Surg. 1994; 58: 1702-1708Abstract Full Text PDF PubMed Scopus (214) Google Scholar]Issues. Suboptimal brain oxygenation during hypothermia: stat versus pH-stat blood gases. Introduction. In patients undergoing cardiopulmonary bypass (CPB), jugular bulb desaturation may be associated with postoperative neurocognitive dysfunction. We examined jugular bulb oximetry (SjvO2) and oxygen tension (PjvO2) in patients undergoing CPB with pH-stat perfusion management. Methods. Jugular bulb catheters were inserted in 12 patients undergoing hypothermic CPB for coronary artery bypass. Jugular bulb temperature was monitored continuously. Jugular venous blood was sampled at intervals during cooling, rewarming, and after bypass. SjvO2 was measured by cooximeter (AVOX System 4000). PjvO2 was measured by gas analyzer (Nova Stat Profile Ultra) and recorded both uncorrected at 37°C (stat) and temperature corrected (pH-stat). Results. SjvO2 decreased as jugular bulb temperature increased. However, only 2 patients demonstrated jugular bulb desaturation (<50%) during rewarming, both when jugular venous temperature exceeded 37.5°C. Desaturation during rewarming was not consistently associated with low PjvO2 values (<27 mm Hg). During cooling and hypothermia, PjvO2 (pH-stat values) were lower than PjvO2 (stat values) and may reflect a more accurate measure of brain oxygenation. Conclusions. During CPB, SjvO2 decreased as jugular bulb temperature increased, with desaturation noted during hypothermia. Therefore, brain oxygenation may be jeopardized in the presence of marked hypothermia. We also noted that, during cooling and hypothermia, PjvO2 measured with pH-stat technique was much lower than that measured with a stat technique. The significance of this finding requires further investigation. [1Croughwell N. Newman M. Blumenthal J. et al.Ann Thor Surg. 1994; 58: 1702-1708Abstract Full Text PDF PubMed Scopus (214) Google Scholar] Issues. Suboptimal brain oxygenation during hypothermia: stat versus pH-stat blood gases.