The Effects of Fire Fighting and On-Scene Rehabilitation on Hemostasis

Details

• Personal Author:
  Fahey GC ; Fernhall B ; Horn, Gavin P. ; Petruzzello SJ ; Smith, Denise L. ; Woods J
• Description:
  Fire fighting is a dangerous occupation - in part because firefighters are called upon to perform strenuous physical activity in hot, hostile environments. Each year, approximately 100 firefighters lose their lives in the line of duty and tens of thousands are injured. Over the past 15 years, approximately 45% of line of duty deaths have been attributed to heart attacks and another 650-1,000 firefighters suffer non-fatal heart attacks in the line of duty each year. From 1990 to 2004, the total number of fireground injuries has declined, yet during this same period, the number of cases related to the leading cause of injury - overexertion/strain - remained relatively constant. It is well recognized that fire fighting leads to increased cardiovascular and thermal strain. However, the time course of recovery from fire fighting is not well documented, despite the fact that a large percentage of fire fighting fatalities occur after fire fighting activity. Furthermore, on scene rehabilitation (OSR) has been broadly recommended to mitigate the cardiovascular and thermal strain associated with performing strenuous fire fighting activity, yet the efficacy of different rehabilitation interventions has not been documented. Twenty-five firefighters were recruited to participate in a "within-subjects, repeated measures" study designed to describe the acute effects of fire fighting on a broad array of physiological and psychological measures and several key cardiovascular variables. This study provided the first detailed documentation of the time course of recovery during 2½ hours post-fire fighting. Additionally, we compared two OSR strategies (standard and enhanced) to determine their effectiveness. As expected, a short term bout (18 minutes) of fire fighting activity resulted in significant physiological, psychological, and cardiovascular strain. Immediately post-fire fighting, core temperature, heart rate, blood pressure and blood catecholamine levels were significantly elevated from baseline conditions. Platelet function and number, along with coagulatory and fibrinolytic variables, showed significant increases from baseline, suggesting that the hemostatic equilibrium was disrupted. Vascular function was significantly affected, as evidenced by a reduction in the ability to perfuse myocardial tissue (measured through the Subendocardial Viability Ratio - SEVR). Finally, firefighters' psychological state became significantly more dysphoric postfire fighting. Importantly, the time rate of recovery from many of these effects appeared to be closer to several hours instead of minutes (as is often assumed). Heart rate and core temperature did not return to baseline levels for up to 60 minutes into the recovery. Blood pressure was found to drop very rapidly in many individuals during rehab, suggesting that we must be aware of the risk of syncope during rehab procedures. Vascular recovery data also showed that SEVR did not return to baseline for up to 60-90 minutes into recovery. After 120 minutes of recovery, it was found that fibrinolytic markers returned to baseline levels, but coagulation (specifically Factor VIII and platelet function) remained significantly elevated. As many heart attacks on the fireground occur following fire suppression, these results suggested a possible mechanism for the increased risk. At the 120 minute recovery period, firefighters' psychological state appeared to have returned to baseline conditions. OSR had no effect on core temperature, suggesting that the active cooling process was no more effective than passive cooling in cool environmental conditions in which rehab was conducted in a cool room. There was also no significant effect on blood pressure, coagulation or fibrinolytic variables or psychological measures as a result of the enhanced rehab protocol. The enhanced rehab protocol resulted in significantly elevated heart rate throughout recovery and a statistically significant delayed return to baseline for both heart rate and SEVR. However, the practical/clinical significance of these small differences in heart rate are unclear. Platelet number was also significantly elevated in the enhanced condition compared to the standard (which had returned to baseline after 120 minutes of recovery). Each group was equally hydrated from baseline levels (based on changes in plasma volume), so this effect is not due to hemoconcentration. Finally, epinephrine levels remained elevated after 120 minutes of recovery in the standard condition, but returned to baseline in the enhanced condition, potentially due to the additional ingestion of carbohydrates in the recovery drink. [Description provided by NIOSH]
• Subjects:
  Emergency Responders Firefighters Heat Stress Disorders Hot Temperature Mortality Occupational Health Safety Temperature
• Keywords:
  Cardiovascular System Emergency Responders Fatalities Fire Fighters First Responders Heart Attacks Heat Stress Overexertion Physiological Effects Temperature Effects
• Publisher:
  University of Illinois at Urbana-Champaign
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Report
• Place as Subject:
  Illinois ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-29
• NIOSHTIC Number:
  nn:20059518
• Citation:
  Champaign, IL: University of Illinois at Urbana-Champaign, 2010 Nov; :1-29
• Contact Point Address:
  University of Illinois Fire Service Institute, 11 Gerty Drive, Champaign, IL 61820
• Federal Fiscal Year:
  2011
• Performing Organization:
  University of Illinois at Urbana-Champaign
• Peer Reviewed:
  False
• Start Date:
  20070901
• Source Full Name:
  The effects of fire fighting and on-scene rehabilitation on hemostasis
• End Date:
  20100831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:498e50e99c9dbeaf80712a84be5bd7c13d6a66968605c3c20465a241e7e8f8ec039b8c58ea4ff4b60674f8e6f47e12f3cc4386afbcf5fa8cab68dec1a81a0344
• Download URL:
  https://stacks.cdc.gov/view/cdc/223715/cdc_223715_DS1.pdf
• File Type:
  [PDF - 1.40 MB ]