Clinical trial NCT04469803: Impact of Intra-Shift Napping on EMS Cardiovascular Health
Official title: The Impact of Napping During Night Shifts on Indicators of Cardiovascular Health Among EMS Clinicians
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Blood Pressure
Heart Rate Variability
Lead sponsor: University of Pittsburgh
Sponsor class: OTHER
Collaborators: name: ZOLL Foundation
First posted: 2020-07-14
Enrollment: 28
Sex: ALL
Minimum age (years): 18
Maximum age (years): 100
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: Randomized crossover study design
Primary purpose: OTHER

Brief summary: Cardiovascular disease (CVD) exerts a significant health burden among shift workers, including police, firefighters, and emergency medical services (EMS). The unique occupational demands inherent to these professions--sleep loss, circadian misalignment, high stress, and sustained hyper-vigilance--confer increased risk for both on and off-duty cardiovascular events. Mitigating cardiovascular risks in these professions requires that we first identify robust markers and potential mechanisms of risk. Previous work suggest shift work has a negative impact on blood pressure (BP) and heart rate variability (HRV). Blunted BP dipping at night and during sleep, and reduced HRV are powerful markers of increased CVD risk. Both are linked to preclinical indicators of cardiac damage, such as presence of coronary artery calcium, left atrial enlargement, and cardiovascular-related mortality. This study will use an experimental crossover study design with three intervention conditions to test the impact of a 30 minute brief nap and a 2-hour longer nap versus no nap on BP and HRV. Outcomes of interest include blunted dipping of BP during nighttime hours and during sleep and HRV.

Detailed description: Cardiovascular disease (CVD) exerts a significant health burden among shift workers, including police, firefighters, and emergency medical services (EMS). The unique occupational demands inherent to these professions--sleep loss, circadian misalignment, high stress, and sustained hyper-vigilance--confer increased risk for both on and off-duty cardiovascular events. Mitigating cardiovascular risks in these professions requires that we first identify robust markers and potential mechanisms of risk. Previous work suggest shift work has a negative impact on blood pressure (BP) and heart rate variability (HRV). Blunted BP dipping at night and during sleep, and reduced HRV are powerful markers of increased CVD risk. Both are linked to preclinical indicators of cardiac damage, such as presence of coronary artery calcium, left atrial enlargement, and cardiovascular-related mortality.

Critical questions remain:

Are BP dipping and HRV impacted by napping during night shift work? Compared to those who do not nap, does napping during night shifts help BP and HRV to normalize quicker in the hours immediately post night shift work? What is the impact of brief naps (e.g., 30 minutes) versus longer naps (e.g., 2 hours)?

This study will use a randomized crossover experimental design of EMS workers and be based in the laboratory environment. Participants will complete three intervention conditions. All study arms will involve a 12-hour simulated night shift. The intervention of interest is napping (no nap vs. a 30 minute nap vs. a two-hour nap) in a randomized crossover study design. The primary outcome of interest is BP dipping (\>10% drop) and Heart Rate Variability (HRV) measured as the standard deviation of inter-beat intervals of the sinus beats in milliseconds (SDNN). All outcomes will be measured serially before the simulation, during simulated night shifts, during the intra-shift napping period, and during recovery.

Eligibility criteria: Inclusion Criteria:

1. age 18 years or older;
2. current / active certification as an EMS clinician at the EMT-Basic, Advanced, Paramedic, Flight Paramedic, or Flight Nurse level, or healthcare shift worker;
3. has not ever been diagnosed with any of the following: hypertension, cardiovascular disease, myocardial infarction, stroke/TIA, chronic kidney disease, adrenal disease, thyroid disease, rheumatologic disease, hematologic disease, cancer of any type, dementia/memory loss, organ transplantation; insomnia or other major sleep problem; sleep apnea or other diagnosis that is related to problems with breathing or the airway; and
4. is not currently pregnant.

Exclusion Criteria:

1. 17 years of age or younger;
2. not an EMS clinician or inactive as an EMS clinician or not a healthcare shift worker;
3. has ever been diagnosed with hypertension, cardiovascular disease, myocardial infarction, stroke/TIA, chronic kidney disease, adrenal disease, thyroid disease, rheumatologic disease, hematologic disease, cancer of any type, dementia/memory loss, organ transplantation; insomnia or other major sleep problem; sleep apnea or other diagnosis that is related to problems with breathing or the airway;
4. is currently pregnant;
5. is unwilling to wear multiple monitoring devices (e.g., automated blood pressure monitoring device, holter monitor for HRV measurement, wrist actigraphy) for the duration of the study protocol.
6. is unwilling to refrain from caffeine during the study protocol; or
7. is unwilling to adhere to sleep / wake times outlined in the study protocol.

Primary outcomes:
measure: Number of participants with blunted dipping of blood pressure via the sleep based method
timeFrame: Blood pressure will be monitored with automated devices at 1-hour intervals over 72 total hours
measure: Number of participants with blunted dipping of blood pressure via the wide fixed time method
timeFrame: Blood pressure will be monitored with automated devices at 1-hour intervals over 72 total hours
measure: The number of participants with unhealthy Heart Rate Variability (HRV) measured via the standard deviation of the inter-beat intervals of normal sinus beats (SDNN)
timeFrame: HRV will be monitored with a holter monitor continuously over 72 total hours
Secondary outcomes:
Other outcomes:
Locations:
city: Pittsburgh
country: United States
facility: University of Pittsburgh
state: Pennsylvania
Study officials:
affiliation: University of Pittsburgh
name: Leonard Weiss, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Pittsburgh
name: P. Daniel Patterson, PhD
role: STUDY_DIRECTOR
References:
citation: Patterson PD, Weiss LS, Weaver MD, Salcido DD, Opitz SE, Okerman TS, Smida TT, Martin SE, Guyette FX, Martin-Gill C, Callaway CW. Napping on the night shift and its impact on blood pressure and heart rate variability among emergency medical services workers: study protocol for a randomized crossover trial. Trials. 2021 Mar 16;22(1):212. doi: 10.1186/s13063-021-05161-4.