Mobile Chemical Detector (AP2C+SP4E) as an Aid for Medical Decision Making in the Battlefield

Abstract

The combination of the AP2C unit with the SP4E kit composes a lightweight mobile detector of chemical warfare agents (CWA), such as nerve and mustard agents, with both vapor- and liquid-sampling capabilities. This apparatus was recently introduced into our military medical units as an aid for detection of CWA on casualties. Importantly, critical information regarding the applicability in the battlefield was absent. In view of the serious consequences that might follow a proclamation of CWA recognition in battlefield, a high false-positive rate positions the utilization of this apparatus as a medical decision tool in question. We have therefore conducted a field experiment to test the false-positive rate as well as analyze possible factors leading to false-positive readings with this device. The experiment was carried out before and after a 4-day army field exercise, using a standard AP2C device, a SP4E surface sampling kit, and a specially designed medical sampling kit for casualties, intended for medical teams. Soldiers were examined at rest, after mild exercise, and after 4 days in the field. The readings with AP2C alone were compared to the combination of AP2C and SP4E and to the medical sampling kit. Various body fluids served as negative controls. Remarkably, we found a false-positive rate of 57% at rest and after mild exercise, and an even higher rate of 64% after the 4-day field exercise with the AP2C detector alone, as compared to almost no false-positive readings with the combination of AP2C and SP4E. Strikingly, the medical sampling kit has yielded numerous false-positive readings, even in normal body fluids such as blood, urine, and saliva. We therefore see no place for using the medical sampling kit due to an unaccepted high rate of false-positive readings. Finally, we have designed an algorithm that uses the entire apparatus of AP2C and SP4E as a reliable validation tool for medical triage in the setting of exposure to nerve agents in the battlefield.

Impedance Based Detection of Chemical Warfare Agent Mimics Using Ferrocene-Lysine Modified Carbon Nanotubes

“…Point (or in situ) detectors respond to the presence of CWAs in the immediate vicinity of the detector. Common techniques which are used in point detectors include ion mobility spectrometry, flame photometry, mass spectrometry, − photoacoustic infrared spectroscopy, surface acoustic wave techniques, electrochemistry, , and “wet chemistry” detection kits . Point detectors often offer good sensitivity at an affordable price, but some techniques (such as “wet chemistry” methods) may not be suitable for continuous monitoring.…”

Investigation of the Persistence of Nerve Agent Degradation Analytes on Surfaces through Wipe Sampling and Detection with Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectrometry

“…Direct extraction of the surface or complete removal of contaminated material may be the most rigorous approach; however, it may not always be possible or desirable, especially when considering waste management costs. Field instrumentation can be used as a screening tool to identify areas where CWAs may exist; however, field instrumentation may result in false positives, − increasing the number of samples generated for analysis. Wipe sampling is a preferred collection procedure because it can be performed quickly and easily during the initial incident response and remediation phase without the destruction of the tested surface. ,, Complications associated with wipe sampling and analysis for both parent CWAs and their degradation analytes from surfaces should be considered.…”