Why is it septic shock important?
In a healthy body, cells are perfused with blood being routed through the local capillary bed. The capillary blood delivers oxygen and nutrients to cells and carries away cellular waste products. During septic shock, capillary bed blood flow is disrupted. If this condition persists, cells begin to die from lack of oxygen – ultimately leading to organ failure or death.
Clinical Monitoring of Septic Shock:
In order to detect septic shock, clinicians need a tool to measure the oxygen inside cells. Poor perfusion is not easily detected by conventional medical equipment. When physicians suspect shock, they typically monitor heart rate and blood pressure. However, vital signs are imprecise and indirect measures of shock, leaving clinicians to guess what condition their patients are in and if they are heading into trouble.
Intermittent blood sampling is another tool used by hospitals, done mainly to measure lactate as an indicator of shock. However, the presence of lactate is a lagging indicator of metabolic response to cellular hypoxia (low oxygen levels). Also, lactate is not a continuous measurement – measured once per hour, at most – further delaying the immediate response necessary for life-saving intervention.
Invasive catheters can be placed to monitor arterial and venous blood oxygen, but catheters are expensive and require expertise not often available in the emergency department. For this reason, catheters are not typically used as a triage tool. Following intervention, it’s difficult to determine if a patient’s oxygenation status has been restored.
Why not use pulse oximetry?
Pulse oximeters are widely used to measure the oxygen bound to hemoglobin in arterial blood. Normal pulse oximeter readings indicate that blood is circulating and gas is exchanging in the lungs. Pulse oximeters do not monitor tissue perfusion. As shown in the chart below, pulse oximetry may be very steady and normal while the underlying cellular oxygenation from the CellSat™ 100 warns of the onset and progression of shock.lular shock.
Septic shock is defined as a “subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone”
Perfusion is the flow of blood through a selected tissue or organ within the body. A direct measure of perfusion is injecting microspheres into the blood stream and then determining how many are lodged into individual tissues/organs.
Cell oxygenation is the measure of intra-cellular oxygen. With the CellSat 100, we measure cellular oxygen bound to myoglobin in muscle tissue.
University of Washington
4000 Mason Road, Suite 300
Seattle, WA 98195