Targeting skeletal muscle tissue oxygenation (StO₂) in adults with severe sepsis and septic shock: a randomised controlled trial (OTO-StS Study)

Objective: Evaluation of the ratio of oxyhaemoglobin to total haemoglobin in skeletal muscle (StO₂) using near-infrared spectroscopy may aid in the monitoring of patients with sepsis. This study assessed the benefits and risks of targeting StO₂ in adults with severe sepsis or septic shock.

Design: A European randomised controlled trial was performed on two parallel groups.

Setting: Five intensive care units (ICU) in France, Greece, Spain and Germany were used for the study.

Participants: A total of 103 adults with severe sepsis or septic shock on ICU admission were randomised (54 subjects in the experimental arm and 49 subjects in the control arm).

Interventions: Haemodynamic management using an algorithm that was adapted from the 2004 Surviving Sepsis Campaign guidelines with (experimental arm) or without (control arm) targeting an StO₂ value greater than 80% at a minimum of two different sites.

Outcomes: The primary outcome was a composite: 7-day all-cause mortality or worsening of organ function, defined as a positive difference in Sepsis-related Organ Failure Assessment (SOFA) score between day 7 and randomisation (ie, delta SOFA >0). Secondary endpoints: 30-day mortality, duration of mechanical ventilation and vasopressor therapy up to 30 days from randomisation.

Results: The study ended prematurely due to lack of funding after enrolment of 103/190 patients. Eighteen patients (33.3%) in the experimental arm and 14 (28.6%, P=0.67) in the control arm died or exhibited delta SOFA >0 on day 7. The mean number of days on mechanical ventilation was 12.2±10.6 in the experimental group and 7.6±7.9 in the control group (P=0.03). Thirty-one (57%) patients in the experimental arm and 14 (29%) patients in the control arm received red cells by day 7 (P=0.01).

Conclusion: Despite the limitation related to premature termination, this study provides no data to support the routine implementation of resuscitation protocols incorporating StO₂ >80% at two or more muscle sites as a target. StO₂-guided therapy may be associated with prolonged use of mechanical ventilation and an increased number of red blood cell transfusions.

Trial registration number: NCT00167596; Results.