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Optical-thermal characterization of cutaneous transilluminators
T Joshua Pfefer1, Ali Mehrabi, Robert James
1Center for Devices and Radiological Health, Food and Drug Administration, 10903 New Hampshire Ave, Silver Spring, MD, 20993, USA. joshua.pfefer@fda.hhs.gov
Physics in Medicine and Biology
|October 30, 2009
Summary
Battery-powered transilluminators (BPTs) using LEDs are popular for vascular access. While generally safe, white LED BPTs can cause significant tissue warming, necessitating further research on neonatal thermal injury thresholds.
Area of Science:
- Biomedical Engineering
- Medical Device Safety
- Optical Engineering
Background:
- Light-emitting diode (LED)-based, battery-powered transilluminators (BPTs) are increasingly used for transdermal vascular access.
- Concerns exist regarding the undocumented optical and thermal outputs of BPTs and the lack of established safety limits.
- Previous devices using high-power broadband lamps posed a higher risk of skin burns.
Purpose of the Study:
- To characterize and assess the optical and thermal outputs of six commercially available BPTs.
- To evaluate the potential for thermal damage associated with BPT use.
- To determine if ambient air measurements are indicative of worst-case thermal scenarios.
Main Methods:
- Optical measurements included spectral irradiance and peak local irradiance for red, orange, and white LED BPTs.
- Thermal measurements involved transient temperature readings in ambient air and ex vivo tissue (pre-heated to 37°C) over 4 minutes.
- Thermal damage potential was analyzed using temperature limits and the Arrhenius equation.
Main Results:
- Non-white-light LED BPTs caused a maximum mean tissue temperature rise of 2.5°C.
- White-light LED BPTs with high irradiance resulted in a mean tissue temperature rise of 9.1°C.
- Device heat generation was the primary cause of temperature increase; no devices exceeded thermal damage thresholds under normal use.
Conclusions:
- Ambient air temperature measurements can effectively identify worst-case BPT thermal outputs.
- While current BPTs appear safe under normal operating conditions, LED-based medical devices warrant further safety research.
- Additional investigation into neonatal thermal injury thresholds related to BPTs is crucial.
