Please see Bibliography of References for a list of abstracts, manuscripts and posters.

Other Studies

Tissue oxygen saturation during cardiac surgery is associated with post-operative recovery

Sanders J, Toor I, Yurik T, Smith A, Keogh BE, Montgomery HE, Mythen M. Int Care Med. 2008;34(1):S189. Abstract 0737.

Introduction: Near Infra-Red Spectroscopy is a novel method for rapid and noninvasive assessment of tissue oxygen saturation (StO₂). An association between StO₂ (%) and oxygen delivery has been demonstrated during shock, trauma and resuscitation. We sought to explore StO₂ during cardiac surgery and its association with post-operative outcome.

Methods: 74 adult patients undergoing first-time, elective, single procedure cardiac surgery requiring cardiopulmonary bypass (CPB) were studied. StO₂ was measured from the thenar eminence (Inspectra Tissue Spectrometer Model 325, Hutchinson Technology Inc, USA) through anaesthesia and surgery, and arrival on the Intensive Care Unit (ICU). Outcome was defined as length of ventilation and ICU stay, post-operative length of stay and morbidity outcome (POMS) on post-operative days 1, 3, 5, 8 and 15 (the presence or absence of a infectious, pulmonary, cardiovascular, wound, haematological, pain, renal or gastrointestinal complication). All clinical information was prospectively collected.

Results: StO₂ rose from baseline during induction of anaesthesia (81.7 to 88.5, p\0.001) then fell during surgery (mean 78.9) with a significant change in minimum StO₂ during CPB (75.9 to 68.2 p\0.0001). The mean StO₂ during the 1st 5 minutes of anaesthesia was lower in those patients with than without POMS on D15 (81.1 ± 7.0 v 87.6 ± 7.7, p = 0.04) with the mean StO₂ during those first 5 minutes being predictive of the presence of D15 POMS (ROC 0.762, p = 0.01). Lower mean StO₂ during the first 20 minutes of ICU monitoring was observed in those with than without POMS on D3 (72.9 ± 12.9 v 85.5 ± 8.4, p = 0.009) and was predictive of the presence of D3 POMS (ROC 0.793, p\0.0001).

Conclusion: StO₂ during anaesthesia and ICU is predictive of post-operative complications on D15 and D3 respectively, with lower StO₂ being associated with poorer outcome. Such data suggest that reduced tissue oxygen delivery, as measured by StO₂, may be associated with poorer outcome - an association which may in theory be causal. Were this the case, interventions targeted at maintaining StO₂ may beneficially impact on such outcome. This hypothesis seems worthy of further exploration.

Grant Acknowledgement: This work was supported by an unrestricted educational grant from Hutchison Technology (Inc). We are indebited to the patients and staff at the Heart Hospital, London for their support and cooperation.