Authors: Asif H M et al.
Source: Anesthesiology, January 30, 2026, 10.1097/ALN.0000000000005911
Summary:
This exploratory observational study investigated how common intraoperative anesthetic and physiologic variables influence human spinal cord blood flow during spinal surgery. Using laser speckle contrast imaging, a noninvasive technique capable of generating high-resolution, real-time blood flow maps, the authors examined the effects of sevoflurane concentration, arterial carbon dioxide tension (PaCO₂), mean arterial pressure (MAP), temperature, and surgical stimulation on spinal cord perfusion.
Thirty-five patients undergoing elective laminectomy procedures, as well as participants in clinical studies of acute traumatic spinal cord injury, were evaluated intraoperatively. Most patients received propofol-based anesthesia, while a subset received sevoflurane. Two craniotomy patients served as physiologic controls to validate the imaging technique by confirming expected cerebral blood flow responses to changes in sevoflurane MAC and PaCO₂.
Increasing sevoflurane concentration produced the anticipated dose-dependent increase in cerebral blood flow in control patients but had no significant effect on spinal cord blood flow when MAP and PaCO₂ were held constant. This suggests that spinal cord vasculature is less sensitive to volatile anesthetic concentration than cerebral vessels. In contrast, increases in PaCO₂ reliably increased spinal cord blood flow across anesthetic techniques, confirming preserved carbon dioxide reactivity. Higher sevoflurane concentrations appeared to augment the spinal cord blood flow response to PaCO₂, indicating enhanced CO₂ sensitivity.
Changes in irrigation fluid temperature had minimal impact on spinal cord blood flow, suggesting that spinal cord temperature is driven primarily by systemic temperature rather than local irrigation. Assessment of autoregulation demonstrated preserved spinal cord autoregulation in patients without traumatic injury, while autoregulation was frequently impaired within injured spinal cord tissue. These findings parallel cerebral autoregulation physiology and support the concept of optimizing spinal cord perfusion pressure in patients with spinal cord injury.
Electrical stimulation of the dorsal columns produced rapid, bilateral increases in spinal cord blood flow, providing direct evidence of neurovascular coupling within the human spinal cord. The authors note several limitations, including small sample size, patient heterogeneity, limited measurement depth, and non-standardized protocols, but emphasize that the study provides rare intraoperative insight into human spinal cord perfusion physiology.
Key Points:
• Laser speckle contrast imaging enables real-time intraoperative measurement of spinal cord blood flow
• Sevoflurane concentration did not significantly alter spinal cord blood flow
• PaCO₂ is a potent regulator of spinal cord perfusion
• Spinal cord autoregulation is preserved in uninjured cord and often impaired after injury
• Neurovascular coupling exists in the human spinal cord
• Hypocarbia may risk spinal cord hypoperfusion in vulnerable patients
• Findings support targeted spinal cord perfusion strategies, especially in trauma
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