This prospective study was aimed to test the hypothesis that tissue hemoglobin oxygen saturation (StO2) measured noninvasively using near-infrared spectroscopy is a reliable indicator of global oxygen delivery (DO2) measured invasively using a pulmonary artery catheter (PAC) in patients with septic shock. The study setting was a 26-bed medical-surgical intensive care unit at a university hospital. Subjects were adult patients in septic shock who required PAC hemodynamic monitoring for resuscitation. Interventions included transient ischemic challenge on the forearm. After blood pressure normalization, hemodynamic and oximetric PAC variables and, simultaneously, steady-state StO2 and its changes from ischemic challenge (deoxygenation and reoxygenation rates) were measured. Fifteen patients were studied. All the patients had a mean arterial pressure above 65 mmHg. The DO2 index (iDO2) range in the studied population was 215 to 674 mL O2/min per m. The mean mixed venous oxygen saturation value was 61% ± 10%, mean cardiac index was 3.4 ± 0.9 L/min per m, and blood lactate level was 4.6 ± 2.7 mmol/L. Steady-state StO2 significantly correlated with iDO2, arterial and venous O2 content, and O2 extraction ratio. A StO2 cutoff value of 75% predicted iDO2 below 450, with a sensitivity of 0.9 and a specificity of 0.9. In patients in septic shock and normalized MAP, low StO2 reflects extremely low iDO2. Steady-state StO2 does not correlate with moderately low iDO2, indicating poor sensitivity of StO 2 to rule out hypoperfusion. Copyright © 2011 by the Shock Society.
|Publication status||Published - 1 May 2011|
- hemodynamic monitoring
- near-infrared spectroscopy
- tissue oxygenation