(Also see FAQ: What is the relationship between InSpectra StO2and lactate?)
Summary
|
|
InSpectra™ StO2 |
Base Deficit |
|
Direct measure of the adequacy of oxygen available to tissues? |
Yes, percent hemoglobin oxygen saturation measured primarily in the microcirculation, where oxygen is delivered to tissue cells |
No, accumulates in tissue and blood as a result of inadequate oxygen available to tissue cells |
|
Noninvasive? |
Yes |
No, blood sample, often arterial |
|
Continuous measurement? |
Yes |
No |
|
Measurement update frequency? |
Continuous measurement with 2-second updates |
Measurement availability variable dependent on hospital practice e.g. 15-minute to 4-hour intervals |
|
Used for clinical assessment of |
Oxygen availability to tissue cells i.e. tissue perfusion status or tissue oxygenation |
Global assessment of metabolic acidosis or compensated respiratory alkalosis |
|
Changes with onset of shock? |
Yes, InSpectra StO2 changes real-time with changes in tissue perfusion1 |
Yes, Base Deficit increases as a result of inadequate oxygen available to tissue cells as in metabolic acidosis or compensated respiratory alkalosis. Administration of bicarbonate can lower the value without changing the underlying medical condition. |
|
Responds to interventions targeted at improving tissue perfusion status? |
Yes, immediate, real-time response to interventions that improve perfusion status1 |
Yes,normalizes with resuscitation and hemorrhage control, but can also be elevated by several other factors that cause acidosis i.e. alcohol, ketoacidosis, renal insufficiency, and drugs |
Background
HTI’s InSpectra™ StO2 Trauma Study
The InSpectra StO2 Trauma Study was a multicenter, prospective, observational, nonrandomized cohort study at seven Level 1 trauma centers in the U.S., which enrolled 383 severely injured trauma patients immediately upon trauma center arrival. (See Cohn et al. J Trauma. 2007;62:44-55 for complete study protocol and results).
InSpectra™ StO2 measurements within the first hour after admission to the emergency department have previously been shown to be equivalent or superior in predictive power to minimum systolic blood pressure (SBP) or maximum base deficit (BD) for progression to multiple organ dysfunction syndrome (MODS) or death in trauma patients.2
Massive Transfusion (MT) Cohort Study
In this more severely ill cohort who received a MT, BD did not emerge as an independent predictor of bad outcome most likely because the majority of these patients had high BDs.
InSpectra StO2 can assist in identifying patients who are going to have a bad outcome and therefore warrant more aggressive interventions. Within the first 3 hours, InSpectra StO2 was the only consistent independent predictor of poor outcome in patients who require MT.3
In Summary
Base deficit is not a consistent measure of tissue oxygenation.
· Many reasons for acidosis (renal insufficiency, drugs, ketoacidosis, alcohol).4
· Normal saline infusion can increase acidosis.
· Bicarb administration can falsely lower the value.
· Lag time of measurement. Not a real-time measurement of the present.
· BD is an indicator of global perfusion adequacy and may not always be sensitive to peripheral hypoperfusion.
· The value of BD in trauma as a predictor of outcome depends on the mechanism of injury (MOI).5
· Can be normal in early hemorrhagic shock and can be altered by pre-existing medical conditions.
· Minimum InSpectra StO2 predicts MODS and mortality in normothermic and hypothermic patients.6