Heat Illness at the Grand Canyon

LT Jennifer Cheng-Dobson

Public Risk Management Program

National Park Service

USPHS Scientific and Training Symposium 2012

June 20, 2012

Background

• American Great Outdoors 50-State Report• Grand Canyon National Park

– 4 million visitors (Apr-Sep)– >100 (rim) and >120 degrees F (floor)– 7000 feet altitude

• 20% of visitors hike in canyon• Heat-related illness

Grand Canyon National Park

Hiking in Grand Canyon

Methods

• 6 year retrospective study• Apr 1 – Sep 20, 2004-2009• EMS run sheets• HRI case criteria:

1. > 1 hour of heat exposure and

2. EMS documented two or more HRI symptoms; or

3. Self-report of HRI

Results

• 6 fatal HRI– 83% male– 66.6% between ages

25-65 years

• 474 non-fatal HRI– 51% female– Median age: 45 years– 84% US residents

• 35% from AZ, CA, CO

Results – cont.

Hiking in the Canyon• All fatal • 90% of non-fatal

• 46% helicopter rescue• 27% walked• 1% litter carry

Evacuation Assistance (25%)

Heat Diagnoses of Visitors with Heat-related Conditions, Apr-Sep, 2004–09

Preliminary Diagnosis* Number Percent

Heat exhaustion 96 20.25

Dehydration 90 18.99

Hyponatremia 82 17.30

Heat-related Illness (HRI) 74 15.61

Heat cramps/syncope 10 2.11

Rhabdomyolysis 6 1.27

Other (renal failure/heat stroke) 24 5.05

No diagnosis assigned 93 19.60

*more than one diagnosis per person, N=475

Limitations

• Lack of diagnosis on EMS run sheets• Inconsistent documentation of symptoms• Does not include HRI cases from Preventative

Search and Rescue (PSAR) program

Discussion/Conclusion

• Median age of non-fatal HRI: 45 years• 30% in western states• Burden on park staff (EMS/SAR)• Preventative Search and Rescue (PSAR)

program is important• Continue HRI surveillance

Grand Canyon Research Team

Acknowledgements

• CDR Sara Newman, DrPH • CDR Rebecca Noe, RN, MPH• Ekta Choudhary, PhD• Amy Wolkin, MSPH

LT Jennifer Cheng-Dobson, MPH

Injury Prevention Specialist

National Park Service

Jennifer_cheng@nps.gov

(202) 513-7219