CurrentAetnaPolicy 0703

Thermal Perfusion Probe for Monitoring Regional Cerebral Blood Flow

Defines Aetna's coverage stance for thermal perfusion probes used to continuously monitor regional cerebral blood flow in patients with acute neurologic disorders and other indications; applies to Aetna medical benefits and participating providers.

Policy Summary

PayerAetna

PolicyThermal Perfusion Probe for Monitoring Regional Cerebral Blood Flow

Policy CodePolicy 0703

Change TypeNo material change

Effective DateMay 3, 2005

Next Review DateJul 25, 2024

Key ActionDo not submit requests expecting coverage; thermal perfusion probe procedures are considered experimental/investigational and are not covered.

SourceLink

Experimentalcoverage stance

QFlow 500example device

15 ml/100 g/minCBF threshold

No RCTsevidence gap

Coverage Determination

Experimental / Investigational — Not covered because experimental/investigational

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Primary stance: Aetna considers thermal perfusion probe monitoring of regional cerebral blood flow experimental and investigational due to insufficient evidence of clinical value in the management of individuals with acute neurologic disorders (e.g., head injury, subarachnoid hemorrhage, or following neurosurgery) or for other indications.

No randomized trials demonstrating improved clinical outcomes; literature limited to feasibility and technical studies. Per MMM guidance, probe placement and temperature sensitivity are considerations but do not establish clinical benefit.

Aetna considers thermal perfusion probes for monitoring regional cerebral blood flow to be experimental and investigational and they are excluded from coverage. This determination is based on insufficient evidence demonstrating clinical value of these approaches in the management of acute neurologic disorders (for example, head injury, subarachnoid hemorrhage, or following neurosurgery) or for other indications.

Coding and Clinical Thresholds

Relevant ICD-10 CodesICD-10

S02.0xx+	Fracture of skull (specified)
S02.413+	Fracture of base of skull
S02.60x+	Fracture of facial bones (unspecified/other)
S02.92x+	Fracture of skull and facial bones, with or without intracranial injury
S06.0X0A - S06.A1XS	Intracranial injury codes, excluding those with skull fracture
Z13.850	Encounter for screening for traumatic brain injury
Z13.858	Encounter for screening for other nervous system disorders

Key Clinical Thresholds

rCBF threshold for symptomatic vasospasm / hypoperfusion15 ml/100 g/min

Provider Actions and Documentation

Prior Authorization

Prior Authorization / Coverage

Thermal perfusion probe procedures are considered experimental and investigational and are not covered by Aetna.

Thermal perfusion probe for monitoring regional cerebral blood flow is considered experimental/investigational.
Claims for these procedures are subject to denial as not medically necessary.

Denial Risk

Claims for thermal perfusion probe placement and monitoring may be denied because the technology is considered experimental/investigational and there is insufficient evidence of clinical benefit in improving outcomes.

Denial risk for claims relating to thermal perfusion probes (e.g., QFlow 500 and related monitoring)

Documentation Required

Background and Clinical Context

Cerebral blood flow (CBF) is essential for normal brain metabolism, and sustained reductions in CBF can lead to ischemic injury. Insufficient perfusion is a concern in conditions such as traumatic brain injury, subarachnoid hemorrhage, and following neurosurgery, where local or global hypoperfusion may contribute to secondary brain injury.

Thermal diffusion (thermal perfusion) probes are intracerebral devices inserted into brain parenchyma that provide continuous regional CBF measurements and have been evaluated primarily for physiological monitoring and feasibility. Prior studies have reported correlations with other perfusion measures and have used a literature-cited threshold of approximately 15 ml/100 g/min to define hypoperfusion or symptomatic vasospasm, but randomized trials demonstrating that use of these probes improves clinical outcomes are lacking.

Definitions

Thermal Perfusion Probe / Thermal Diffusion Probe (intracerebral probe)

DefinitionAn intracerebral probe inserted via a burr hole into brain parenchyma that measures regional cerebral blood flow continuously by assessing thermal convection/thermal diffusion, connected to an external monitor (e.g., QFlow 500 with Bowman Perfusion Monitor)

Typical placementProbe tip is inserted into white matter within the vascular territory of interest

Measurement characteristicsProvides continuous, regional CBF data at bedside; measurements are sensitive to core body temperature and can be altered by hyperthermia

Multi-modality Monitoring (MMM)

DefinitionA monitoring approach that combines multiple tools (intracranial pressure monitors, transcranial Doppler, thermal diffusion probes, microdialysis catheters, brain tissue oxygen probes, and continuous EEG) to assess cerebral metabolism, perfusion, and oxygenation in neurocritical care

PurposeDetect clinical deterioration from secondary brain injury (inflammation, ischemia, edema) to guide therapy before irreversible injury

Implementation noteThermal diffusion probes for MMM should be placed in the vascular territory of the ruptured aneurysm per consensus guidelines; MMM lacks randomized trials showing outcome benefit