Renal Considerations in the Heat Stress Recommendations (Aim1)

Indiana University

Status: Completed

Conditions: Hot Weather; Adverse Effect; Dehydration; Hyperthermia; Kidney Injury; Kidney Dysfunction

Treatments: Other: 25.5°C WBGT - Fixed Work Rate; Other: 27.5°C WBGT - Fixed Work Rate; Other: 26.0°C WBGT - Fixed work-to-rest ratio; Other: 30.5°C WBGT - Fixed work-to-rest ratio; Other: 30.5°C WBGT - Fixed work-to-rest ratio (high intensity); Other: 35.5°C WBGT - Fixed Work Rate; Other: 23.0°C WBGT - Fixed Work Rate; Other: 28.5°C WBGT - Fixed Work Rate

Study type: Interventional

Funder types: Other

Identifiers

NCT04767347

1902420140

Details and patient eligibility

About

An epidemic of chronic kidney disease is occurring in laborers who undertake physical work outdoors in hot conditions. The reason for this is unknown, but may be related to kidney dysfunction caused by increases in body temperature and dehydration. The current heat stress recommendations for workers were not developed with regards for kidney health. The purpose of this study is to determine if the current recommendations protect against kidney dysfunction.

Enrollment: 38 patients

Sex: All

Ages: 18 to 44 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Men and women
• 18-44 y old
• Body mass index ≤35.0 kg/m2
• Self-reported to be healthy.

Exclusion criteria

• Not within defined age range
• Estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m2
• Deemed highly active according to the physical activity questionnaire (i.e., >3500 MET*min/wk)
• Body mass index >35.0 kg/m2
• Current or history of any renal disease, heart disease, stroke, immune or autoimmune disease, and/or gastrointestinal disease/surgery
• Hypertension during screening (systolic blood pressure >139 or diastolic blood pressure >89)
• Using medications that blunt the physiological response to exercise (e.g., beta blockers)
• Prescription medication with a known side effect of impaired temperature regulation or fluid balance (e.g., diuretics)
• Positive pregnancy test at any time during the study or breast feeding
• Current tobacco or electronic cigarette use or consistent use within the last 2 years
• Inability to safely complete the peak oxygen uptake test

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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38 participants in 2 patient groups

Fixed Work Rate

Experimental group

Description:

Participants will walk on a treadmill at 3 mph and the grade will be adjusted to elicit 430 W of metabolic heat production (the most common work intensity). This study will systematically examine the NIOSH recommendations for prescribing work-to-rest ratios with increasing environmental heat stress (defined as Wet Bulb Globe Temperature, WBGT) at this fixed rate of metabolic heat production on kidney function.

Treatment:

Other: 25.5°C WBGT - Fixed Work Rate

Other: 28.5°C WBGT - Fixed Work Rate

Other: 35.5°C WBGT - Fixed Work Rate

Other: 27.5°C WBGT - Fixed Work Rate

Other: 23.0°C WBGT - Fixed Work Rate

Fixed work-to-rest ratio

Experimental group

Description:

This study will systematically examine the NIOSH recommendations on changes in kidney function when the work-to-rest ratio is fixed at 30 min per hour (the most commonly prescribed work-to-rest ratio), but the rate of metabolic heat production and environmental heat stress differs (Figure 2). As described in Study 1, the appropriate rate of metabolic heat production will be elicited by having participants walk on a treadmill at 3 mph and the grade will be adjusted accordingly.

Treatment:

Other: 30.5°C WBGT - Fixed work-to-rest ratio

Other: 26.0°C WBGT - Fixed work-to-rest ratio

Other: 30.5°C WBGT - Fixed work-to-rest ratio (high intensity)