In-field use of I-VED electrical impedance sensor for assessing post-dive decompression stress in humans

Area of Science:

• Biomedical Engineering
• Diving Physiology
• Medical Diagnostics

Background:

• Ultrasound imaging is standard for detecting venous gas emboli (VGE) after diving, with higher VGE loads correlating to increased decompression sickness (DCS) risk.
• Arterial endothelial dysfunction is also a potential marker for decompression stress.
• Current methods like ultrasound can be operator-dependent and costly.

Purpose of the Study:

• To evaluate a novel electrical impedance spectroscopy technology (I-VED) for detecting post-dive bubbles (VGE) and arterial endothelial dysfunction in human subjects.
• To explore I-VED as a potential non-invasive, cost-effective tool for assessing decompression stress.
• To compare I-VED performance against established markers of decompression stress.

Main Methods:

• I-VED signals were collected from scuba divers during standardized pool dives.
• Signals were recorded pre-dive and at 35-minute intervals for approximately two hours post-dive.
• Two signal frequency components, Low-Pass Frequency (LPF) and Band-Pass Frequency (BPF), were analyzed and correlated with VGE presence and endothelial function.

Main Results:

• Subjects with higher VGE counts exhibited an elevated average LPF, though not statistically significant (p=0.06).
• A significant decrease in BPF standard deviation was observed post-dive compared to pre-dive (p=0.008), indicating potential endothelial dysfunction.
• I-VED provided qualitative in-vivo impedance measurements.

Conclusions:

• I-VED shows promise as a novel technology for assessing decompression stress in human divers.
• The technology is less expensive, not operator-dependent, and suitable for continuous monitoring compared to ultrasound.
• Further calibration and validation are required to establish I-VED's sensitivity and specificity for clinical use.