Non-invasive imaging tests currently used at the bedside to monitor tissue conditions could help in the early detection of sepsis, preclinical research indicates.
The optical spectroscopy technique, reported in The FASEB Journal, could one day be used to initiate sepsis treatment for patients in intensive care before their brains and other vital organs are affected.
A combination of hyperspectral near-infrared spectroscopy (hsNIRS) and diffuse correlation spectroscopy (DCS) was able to detect microcirculatory changes to skeletal muscle before the onset of sepsis in a rats.
Skeletal muscle seemed to act as a more sensitive early indicator of sepsis-related changes in microhemodynamics than the brain.
“Sepsis is a leading cause of death around the world that disproportionately affects vulnerable populations and those in low-resource settings,” said study author Rasa Eskandari, an MD-PhD candidate at Western University in Canada.
“Since early recognition can significantly improve outcomes and save lives, our team is committed to developing accessible technology for early sepsis detection and to guide timely interventions.”
Sepsis is a dysregulated response to infection that can result in life-threatening organ failure, and it disproportionately affects vulnerable and low-income populations.
While the early use of antibiotics to manage infection and vasopressors to address systemic hypotension are linked with improved survival, there is a lack of tools available to recognize its onset.
Noting that peripheral microcirculation is affected early in its course, researchers examined whether a hybrid hsNIRS-DCS system paired with continuous wavelet transform could non-invasively detect signs of sepsis-related microcirculatory impairment in the skeletal muscle earlier than in the brain.
Changes in hemoglobin content, perfusion, oxygenation, and vasomotion were continuously monitored in the skeletal muscle and cerebral microcirculation of a rat sepsis model and compared with control animals.
The rat model of fecal-induced peritonitis had previously been shown to provide a six-hour window between infection and clinical manifestation of sepsis.
Irreversible hypotension, which indicates progression toward septic shock, was observed in 80% of septic animals during the final four hours.
Although peripheral perfusion rapidly decreased in septic animals, there were no significant other changes in microcirculatory measurements.
However, increased vasomotion was detected in the oscillations of all peripheral microhemodynamic parameters—hemoglobin content, oxygenation and perfusion—as well as the oscillations of cerebral hemoglobin content approximately two hours before irreversible hypotension.
Importantly, despite the decrease in peripheral perfusion and increase in vasomotion among septic animals, there were neither indications of tissue hypoxia in the skeletal muscle nor brain. Instead, the coupling of oxygen supply and regulation to tissue oxygen demand appeared to be impaired.
The researchers noted that progressive systemic hypotension and non-responsiveness of vascular resistance to fluids are common in patients with septic shock.
The results of the study therefore suggest that the exaggerated peripheral vasomotion may contribute to the failure of the skeletal muscle arterioles to maintain sufficient resistance and regulate mean arterial pressure.
Overall, the team concluded: “The results of this study suggest that while the brain is partly protected in early sepsis, the skeletal muscle could be an early target for detecting changes in microhemodynamics.”
