Evaluation of Tissue Perfusion in Septic Shock Using Cardiac Output Monitoring and Transcutaneous Oxygen Challenge Test: A Prospective Observational Study

OBJECTIVE: To evaluate tissue perfusion in patients with septic shock using oxygenation and cardiac output monitoring. METHODS: This prospective observational study involved 54 septic shock patients and 29 postoperative controls. Ultrasound was used for velocity time integral (VTI), left ventricular outflow tract diameter, and inferior vena cava diameter. Transcutaneous partial pressure of oxygen was monitored using the SenTec Digital Monitoring System. A 10-minute oxygen challenge test (10min-OCT) and blood gas analyses were performed. Data were collected every 12 hours for 24 hours. Shock patients were divided into survival and death groups according to 28-day prognosis. Cox proportional hazards regression analysis was used for prognostic factors and predictive performance. RESULTS: Compared to the control group, the shock group had lower 10min-OCT, VTI, and stroke volume at enrollment. Shock group VTI remained significantly lower after treatment. 10min-OCT and stroke volume were not significantly different from the control group, while lactate was higher in the shock group. 10min-OCT was lowest after 12 hours of treatment, and mixed venous oxygen content (CvO 2 ) was highest. After 24 hours, VTI was significantly higher than at enrollment. Nonsurvivors had higher lactate and lower arterial oxygen content (CaO 2 ) and CvO 2 than survivors. Lactate (HR 1.489, P < 0.001), CaO 2 (HR 0.322, P < 0.05), and CvO 2 (HR 4.363, P < 0.05) were independent prognosis factors. Combining CaO 2 and CvO 2 with lactate improved prognostic accuracy. CONCLUSION: The 10min-OCT is a reliable, noninvasive marker of microcirculatory perfusion in septic shock with correlation with lactate. VTI was more sensitive than cardiac output or cardiac index in reflecting circulatory status. CaO 2 and CvO 2 were independent predictors of 28-day mortality, and their combination with lactate improved prognostic precision.