Using DC Oximetry to Detect Exhaustion in Working Firefighters

Details

• Personal Author:
  Armstrong L ; Baxter G ; Bogucki, Sandy ; Pranger LA ; Van Gelder CM ; Wiesmann WP ; Armstrong L ; Baxter G ; Bogucki, Sandy ; Pranger LA ; Van Gelder CM ; Wiesmann WP
• Description:
  Objectives: To determine whether noninvasive direct current (DC) oximetry can identify physiological exhaustion in working firefighters (FFs), and to develop experimental models with which to evaluate this technology. Methods: Red LEDs and detecting photodiodes were incorporated into self-contained breathing apparatus (SCBA) face masks for forehead reflectance mode oximetry in working FFs. The pulsatile component of absorbance was processed out to obtain the DC component. In the first experiment, 9 FFs wearing the sensorized SCBAs performed FF tasks in an environmental chamber on 2 separate occasions. In full PPE, FFs completed the protocol at 40 degrees C; 1 week later, they repeated the protocol wearing shorts and T-shirts at 18 degrees C. Oximetry tracings were recorded. Next, wearing dual-wavelength SCBA-based oximeters, 5 FFs in full PPE and a 75-lb weight vest simulating a hose pack exercised on a treadmill at 40 degrees C until fatigued. In addition to absorbance in both red and near-IR ranges, laboratory indices of dehydration and metabolic stress were obtained. Core temperature (Tc) was recorded and heat storage (HS) calculated in both sets of studies. Results: In both experiments, DTc and HS over 10-25 min of exercise exceeded OSHA 8-hour limits. One FF in heat/PPE was unable to complete the protocol in the first set of experiments. A marked negative deflection in the oximetric absorbance tracing corresponding to onset of symptoms was observed. In the second experiment, paired t-test results confirmed significant fluid loss and lactate accumulation in all subjects. Obvious deflections in DC oximetry tracings were seen 10- 30 sec before volitional fatigue in 4/5 subjects. Increased variability in oximetric tracings was seen in all subjects as they fatigued, and an index of variability was developed. Conclusions: Both linear and intermittent exercise models of uncompensable heat stress in FFs suggest that DC oximetry may noninvasively detect exhaustion in working FFs when self-rescue is still possible. [Description provided by NIOSH]
• Subjects:
  Energy Metabolism Firefighters Fires Heat Stress Disorders Hot Temperature Occupational Health Personal Protective Equipment Safety
• Keywords:
  Fire Fighters Fire Safety Heat Exposure Heat Stress Metabolic Effects Monitoring Systems Personal Protective Equipment Physiological Measurements PPE SCBA Self Contained Breathing Apparatus Wearable Technologies

  More +
• ISSN:
  1553-2712
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary ; Abstract or Summary
• Place as Subject:
  Connecticut ; Maryland ; OSHA Region 1 ; OSHA Region 3
• CIO:
  National Institute for Occupational Safety and Health (NIOSH) ; National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health ; Workplace Safety & Health
• Location:
  North America ; North America
• Volume:
  11
• Issue:
  5
• NIOSHTIC Number:
  nn:20052266
• Citation:
  Acad Emerg Med 2004 May; 11(5):605
• Federal Fiscal Year:
  2004
• Performing Organization:
  Sekos, Inc., Germantown, Maryland
• Peer Reviewed:
  True
• Start Date:
  20000930
• Source Full Name:
  Academic Emergency Medicine
• End Date:
  20070930
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:1530b1b20ab8160ecde1671e0a752c63e7b9a19ce5696bdbedfd005e44592bffb8bdb1f84f171c4ca42cd639c622c12d02a228d07c6eb9ece1efabcf8483bba5
• Download URL:
  https://stacks.cdc.gov/view/cdc/211820/cdc_211820_DS1.pdf
• File Type:
  [PDF - 347.43 KB ]