Restoring arterial pressure with norepinephrine improves muscle tissue oxygenation assessed by near-infrared spectroscopy in severely hypotensive septic patients

To examine the consequences of administration of norepinephrine on muscle tissue oxygenation in severely hypotensive septic shock patients. This was a prospective observational study conducted in a medical intensive care unit of a university hospital. We included 28 septic shock patients that received early volume resuscitation. All were eligible for receiving norepinephrine because of life-threatening hypotension and low diastolic arterial pressure. Muscle tissue oxygen saturation (StO(2)) and its changes during a vascular occlusion test were measured at the level of the thenar eminence using a near-infrared spectroscopy (NIRS) device. Transpulmonary thermodilution cardiac index (CI) and NIRS-derived variables were obtained before and after the mean arterial pressure (MAP) was increased by norepinephrine. The baseline StO(2) and the vascular occlusion test-derived variables of 17 healthy volunteers were measured and served as controls. In healthy volunteers, StO(2) ranged between 75 and 90% and StO(2) recovery slopes ranged between 1.5 and 3.4%/s. Administration of norepinephrine, which was associated with an increase in MAP from 54 +/- A 8 to 77 +/- A 9 mmHg (p < 0.05), also induced increases in CI from 3.14 +/- A 1.03 to 3.61 +/- A 1.28 L/min/m(2) (p < 0.05), in StO(2) from 75 +/- A 9 to 78 +/- A 9% (p < 0.05) and in StO(2) recovery slope from 1.0 +/- A 0.6 to 1.5 +/- A 0.7%/s (p < 0.05). Norepinephrine administration aimed at achieving a MAP higher than 65 mmHg in septic shock patients with life-threatening hypotension resulted in improvement of NIRS variables measured at the level of the thenar eminence.