Dr. John Murkin - CAS Critical Care Medicine Award

Dr. John Murkin - CAS Critical Care Medicine Award

Congratulations to Dr. John Murkin!

The Critical Care Medicine Section of the Canadian Anesthesiologists’ Society recently awarded Dr. Murkin the  CAS Critical Care Medicine Award. This was for his abstract, “Initial Soft Tissue Oxygenation is Inversely Associated With Prolonged ICU Admission” (see below), co-authored by Tina Mele, Satoru Fujii, Franklin DaukinsArce, and Tracey Bentall. The study reports on another complication of NIRS to assess patient outcomes and is a peer-review PSI-funded study. This ongoing study has also produced the paper: “Soft tissue oxygenation and risk of mortality(STORM): An early marker of critical illness?” in the Journal of Critical Care (30(2015), 315–320).  Read more on PubMed: https://www.ncbi.nlm.nih.gov/pubmed/?term=25434719  

Initial Soft Tissue Oxygenation is Inversely Associated With Prolonged ICU Admission


Introduction: Unlike pulse oximetry which measures peripheral tissue arterial inflow oxygen saturation, the status of peripheral tissue microcirculatory perfusion and the integrity of tissue flow/demand coupling is reflected by soft tissue oxygenation (StO2) which is measured non-invasively using near infrared reflectance spectrophotometry (NIRS). Critically ill patients often have abnormalities of the microcirculation giving rise to impaired tissue perfusion , hypoxia and ultimately end organ failure, and it has previously been shown that StO2 is an early marker of mortality in critically ill patients prior to admission to Intensive Care Unit (ICU).[1] This study was structured to determine whether sequential StO2 after admission to ICU is associated with adverse outcomes.

Methods: Following institutional Research Ethics Board approval and patient or care-giver consent, a research device (Hutchinson Technologies) was used to measure tissue oximetry from a NIRS sensor placed on the hypothenar eminence of critically ill patients immediately after admission to ICU and at subsequent 12 hourly intervals. Patient demographics, therapeutic interventions and patient outcomes were recorded and analyzed to determine whether there was any correlation between StO2 and mortality , ICU length of stay (LOS) more than 3 days, or hospital LOS more than 10 days.

Results: 126 consecutive consenting adult patients admitted to ICU with primary diagnosis of cardiogenic shock (n= 31), hemorrhagic shock (n= 5), neurogenic shock (n= 1), respiratory failure (n= 44), and septic shock (n= 45), had StO2 measured after admission and at 12 hourly intervals. Using both univariate (p = 0.035) and multivariate (p = 0.009) regression analysis, initial StO2 at ICU admission was strongly and inversely correlated with prolonged ICU stay more than 3 days, and there was also a weak trend (p = 0.98) correlating inverse change in StO2 over time with prolonged hospitalisation (more than 10 days) while StO2 did not correlate with mortality (p = 0.401).

Discussion: Soft tissue oxygenation is a useful screening tool to assess severity of illness upon initial ICU admission and is associated with prolonged ICU stay. However, once treatment has begun other tissue NIRS measures , such as vascular occlusion test (VOT), are associated with mortality and may be better able to guide triage and therapeutic interventions.[2]

1] Kidane B, et al. Soft tissue oxygenation and risk of mortality (STORM): an early marker of critical illness? J Crit Care 2015;30:315-20

2] Murkin JM, et al. Low initial tissue oximetry vascular occlusion test reperfusion slope is associated with mortality in critically ill patients. Anesth Analg 2018 (submitted for publication)