Electrodermal Activity for Prediction and Detection

TritonÆs System using Electrodermal Activity Sensing for the Prediction of Oxygen Toxicity, SEASPOT, is a novel wearable sensor with on-board real-time signal processing capabilities to predict seizure likelihood and to provide a warning to the wearer. Breathing hyperbaric oxygen (HBO2) is used during military and recreational diving operations, during HBO2 therapy for treating problematic wounds, and as an effective treatment for decompression sickness (DCS) where the ensuing large partial pressure gradient for nitrogen diffusion from tissues-to blood-to alveolar gas promotes denitrogenation; that is, removal of nitrogen from the body through pulmonary ventilation. Additionally, prior to decompression, prebreathing 100% oxygen (oxygen prebreathe) has been shown to be an effective method to mitigate DCS. The use of HBO2 in these situations is limited by an increased risk of developing central nervous system oxygen toxicity (CNS-OT). CNS-OT is often preceded by a host of early non-convulsive signs which could impair performance including headache, nausea, tinnitus, lip twitching, and tingling of the limbs. CNS-OT is also characterized by enhanced autonomic activity and abnormal cardiorespiratory changes that ultimately culminate in generalized tonic¢clonic seizures and loss of/altered consciousness followed by cardiogenic pulmonary edema. Losing consciousness and/or convulsing under water could result in dislodgement of a diverÆs gas supply from his or her mouth and could lead to drowning. Likewise, losing consciousness and convulsing for patients undergoing HBO2 therapy could result in further injuries. Previous studies have suggested that electrodermal activity (EDA) can be used to predict seizures. Physiologically, elevated sympathetic activity associated with augmented seizure in humans activity occurs at 1 ATA when breathing air with the risk for developing seizures increasing during protracted breathing of >2.5¢3.0 ATA O2. Because seizure occurrence risk due to CNS-OT varies from person-to-person and dive-to-dive, conservative dive tables have been developed limiting maximum safe depth and dive duration. If CNS-OT symptoms can be predicted, the risk to divers could be reduced by personalizing their safe exposure limits for HBO2 at depth and by allowing them to adjust their depth and gas mixtures preemptively. This same strategy could also optimize the therapeutic and operational uses of HBO2 in hyperbaric, diving, and submarine medicine (e.g., healing problematic wounds or preventing DCS) by tailoring exposures for individuals to their neurological tolerance to HBO2. TrtitonÆs SEASPOT device processes EDA signals in real time using algorithms that have been previously shown to predict seizure onset to alert divers of potential oxygen toxicity issues in time to prepare for and possibly avoid oxygen toxicity consequences.