The Effect of Gentle Exercise Prior to a Cold Sensitivity Test used to Classify Non-Freezing Cold Injury

A cold sensitivity test (CST) is one of the assessments used to classify the level of non-freezing cold injury (NFCI) in patients presented to a cold injury clinic. The CST involves sitting in a chamber at 30°C for at least 30 min then immersing the injured site (usually a foot) in water at 15°C for 2 min. The NFCI classification is based on the skin temperature before and 5 min after immersion. Previous studies have indicated that this test may not be very reproducible. In addition, a proportion of uninjured individuals are classified as having a NFCI if this test is used in isolation. The purpose of this study was to examine whether elevating deep body temperature slightly by gentle exercise prior to conducting a CST would increase the reproducibility of the test. Six male subjects with no history of NFCI undertook 10 CSTs with and without prior exercise (stepping, cycling and arm cranking). The results indicated that stepping for approximately 10 min to elevate deep body temperature by 0.3°C reduced the variability in response observed and produced more “normal” classifications compared to the control condition. An additional finding was that changes in skin temperature were not reflected in changes in blood flow measured using photoplethysmography. The implications of these findings are discussed. 1.0 INTRODUCTION Non-freezing cold injury (NFCI) is a debilitating condition that can result in lifelong cold sensitivity, pain and sweating in the injured part, usually the feet. It is the most common form of non-combative related injury to afflict military forces and is common, at least in a mild form, in those participating in outdoor pursuits. A cold sensitivity test (CST) is one of the assessments used to classify non-freezing cold injury (NFCI) . This involves resting fully clothed in air at 30°C for at least 30 min, the injured area is then placed in a plastic bag and immersed in stirred water at 15°C for 2 min. Following removal from the water, the bag is removed and the patient rests for a further 5 min. Skin temperature (Tsk) is measured from infra-red thermal images of the injured area taken prior to immersion, immediately after, and 5 min after immersion. The degree of NFCI is determined from the temperature of the injured area immediately before immersion, and the amount of rewarming that occurs following removal from the water (Table 1). The assumption being that the higher the starting Tsk and the greater the amount of rewarming of Tsk following cooling, the less severe the cold sensitization/injury. It is further assumed that the increase in Tsk following cooling is indicative of a greater return of peripheral blood flow. Eglin, C.; Golden, F.; Tipton, M. (2005) The Effect of Gentle Exercise Prior to a Cold Sensitivity Test used to Classify Non-Freezing Cold Injury. In Prevention of Cold Injuries (pp. 11-1 – 11-6). Meeting Proceedings RTO-MP-HFM-126, Paper 11. Neuilly-sur-Seine, France: RTO. Available from: http://www.rto.nato.int/abstracts.asp. Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 01 MAY 2005 2. REPORT TYPE N/A 3. DATES COVERED 4. TITLE AND SUBTITLE The Effect of Gentle Exercise Prior to a Cold Sensitivity Test used to Classify Non-Freezing Cold Injury 5a. CONTRACT NUMBER