Abstract
BackgroundThe goal when resuscitating trauma patients is to achieve adequate tissue perfusion. One parameter of tissue perfusion is tissue oxygen saturation (StO2), as measured by near infrared spectroscopy. Using a commercially available device, we investigated whether clinically relevant blood loss of 500 ml in healthy volunteers can be detected by changes in StO2 after a standardized ischemic event.MethodsWe performed occlusion of the brachial artery for 3 minutes in 20 healthy female blood donors before and after blood donation. StO2 and total oxygenated tissue hemoglobin (O2Hb) were measured continuously at the thenar eminence. 10 healthy volunteers were assessed in the same way, to examine whether repeated vascular occlusion without blood donation exhibits time dependent effects.ResultsBlood donation caused a substantial decrease in systolic blood pressure, but did not affect resting StO2 and O2Hb values. No changes were measured in the blood donor group in the reaction to the vascular occlusion test, but in the control group there was an increase in the O2Hb rate of recovery during the reperfusion phase.ConclusionStO2 measured at the thenar eminence seems to be insensitive to blood loss of 500 ml in this setting. Probably blood loss greater than this might lead to detectable changes guiding the treating physician. The exact cut off for detectable changes and the time effect on repeated vascular occlusion tests should be explored further. Until now no such data exist.
Highlights
The goal of resuscitation is to achieve adequate tissue perfusion
The aim of this study was to investigate the impact of a controlled and clinically relevant blood loss (500 ml) on resting StO2 values, as well as microcirculatory reactivity triggered by a vascular occlusion test in healthy blood donors. 500 ml of blood donation correspond to a loss of 10% of the whole blood volume. 10% of blood loss is considered to be the cut off for clinical relevant blood loss according to the current literature and may become relevant if pre- existing morbidity exists
For variables measured with Near infrared spectroscopy (NIRS), the differences from the first to the second vascular occlusion test did not differ between the two groups
Summary
The goal of resuscitation is to achieve adequate tissue perfusion. Near infrared spectroscopy (NIRS) has become a widely used method for tissue hemoglobin oxygen saturation (StO2) measurement in muscle and has been validated in animals [2,3,4] and in humans [5,6,7,8,9,10,11]. The goal when resuscitating trauma patients is to achieve adequate tissue perfusion. One parameter of tissue perfusion is tissue oxygen saturation (StO2), as measured by near infrared spectroscopy. Using a commercially available device, we investigated whether clinically relevant blood loss of 500 ml in healthy volunteers can be detected by changes in StO2 after a standardized ischemic event
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