Critically ill patients in circulatory shock, which occurs when the heart is unable to pump enough blood and oxygen to the rest of the body, often as a result of heart failure, sepsis, or haemorrhage, require close monitoring and treatment, particularly to maintain adequate blood pressure to avoid injury to vital organs.
A team led by researchers at Massachusetts General Hospital (MGH) and MIT recently developed a method for monitoring such patients, which may help clinicians control their blood pressure and heart function to reduce the risk of death and other negative health outcomes.
The findings of the study were published in Nature Medicine.
The work entailed developing a method for measuring a circulation feature known as critical closure pressure, which is the blood pressure at which small blood capillaries collapse and blood flow ceases. Although critical closing pressure can provide an indicator of blood vessel tone in response to disease and therapy, it has not been frequently measured in clinical care.
Development of the new approach utilized high resolution waveform data from blood pressure monitoring of 5,532 patients in the cardiac intensive care unit at MGH. Researchers developed an analysis based on measured parameters (including arterial pressure, pulse pressure, and heart rate) to define the critical closing pressure. They then defined a value called tissue perfusion pressure—calculated as the difference between average arterial blood pressure and critical closing pressure—and found that it predicted a patient’s risk of death, length of hospital stay, and peak blood lactate level (an indicator of tissue oxygenation).
“When treating patients with circulatory shock, it is essential to maintain adequate blood pressure targets, yet standard goals are not personalized to individual patients. We have developed a new metric that can identify individuals with inadequate tissue perfusion who are at risk for adverse outcomes. We believe this method can be used to optimize treatment decisions for patients in the intensive care unit,” says senior author Aaron Aguirre, MD, PhD, an attending cardiologist and critical care specialist at MGH and an assistant professor of Medicine at Harvard Medical School.
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