Effect of Firefighting and On-Scene Rehabilitation on Hemostasis

Details

• Personal Author:
  Fahey G ; Horn G ; Petruzzello S ; Smith, Denise L.
• Description:
  Firefighting 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 continued to decline, yet during this same period, the number of cases related to the leading cause of injury - overexertion/strain - has remained relatively constant. It is well recognized that firefighting leads to increased cardiovascular and thermal strain. However the time course of recovery from firefighting is not well documented despite the fact that a large percentage of firefighting fatalities occur after firefighting activity. Furthermore, on-scene rehabilitation (OSR) has been broadly recommended to mitigate the cardiovascular and thermal strain associated with strenuous firefighting activity, yet the efficacy of 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 firefighting on physiological and psychological measures and several key cardiovascular variables, including those that are directly related to cardiac events. The study also provides the first detailed documentation of the time course of recovery during the 2 ½ hours post-firefighting. Additionally, we compared two OSR strategies to determine their effectiveness. As expected, a short term bout (18 minutes) of firefighting activity results in significant physiological, psychological, and cardiovascular disruptions. Immediately post-firefighting, core temperature, heart rate, blood pressure and blood catecholamine levels are significantly elevated from baseline conditions. Platelet function and number, coagulatory and fibrinolytic variables show significant increases from baseline, suggesting that the hemostatic equilibrium may be elevated, but both clotting and clot breakdown are elevated simultaneously. Vascular function is significantly affected as noted by the reduction in the ability to perfuse myocardial tissue (measured through the Subendocardial Viability Ratio - SEVR). Finally, firefighters' psychological state becomes more dysphoric post-firefighting. Importantly, the time rate of recovery from many of these affects appears to be on the order of 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 shows that SEVR does 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) remains significantly elevated, potentially unbalancing the hemostatic equilibrium in favor of clot formation. As many heart attacks on the fireground occur at this timeframe immediately following fire suppression, these results suggest a possible mechanism for the increased risk. At the 120 minute recovery period, firefighter's psychological state appears to have returned to baseline conditions. The effect of on scene rehabilitation protocol was only measured in a few parameters. OSR had no effect on core temperature, suggesting that the active cooling process was no more affective the passive cooling in cool environmental conditions. There was also no affect on blood pressure, coagulation or fibrinolytic variables or psychological measures. 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. 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 was not due to hemoconcentration. Finally, epinephrine levels remain 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
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  Illinois ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-33
• NIOSHTIC Number:
  nn:20059517
• NTIS Accession Number:
  PB2021-100142
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R03-OH-009111, 2010 Nov; :1-33
• Contact Point Address:
  PI: Gavin Horn, PhD, University of Illinois Fire Service Institute, 11 Gerty Drive, Champaign, IL 61820
• Email:
  ghorn@fsi.illinois.edu
• Federal Fiscal Year:
  2011
• NORA Priority Area:
  Services
• Performing Organization:
  University of Illinois at Urbana-Champaign
• Peer Reviewed:
  False
• Start Date:
  20070901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20100831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:0bfae2b164129c0a3bdcd8e71328cf4a13cc50107f252e2702c37645db04d61d50f7ef82caa0eaa8e5be0717f9ff93d7fc6cfec5958a57db33ed0b10873bb631
• Download URL:
  https://stacks.cdc.gov/view/cdc/218980/cdc_218980_DS1.pdf
• File Type:
  [PDF - 1.19 MB ]