Analysis of Heart Rate Variability During Emergency Flight Simulator Missions in Fighter Pilots

Study Overview
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Brief Summary
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The autonomous response of fighter and attack pilots who attend sessions in a flight simulator will be evaluated by measuring and analyzing heart rate variability (HRV).

Detailed Description
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The autonomous response of fighter and attack pilots during emergency situations in a flight simulator will be assessed by measuring and analysing heart rate variability (HRV). Eighteen pilots with instructor or student status assigned at the time of the evaluation to the ALA 23 district of the Talavera la Real Air Base of the Ministry of Defence of the Spanish Government (Badajoz) were studied during emergency situations in flight simulator. Subjects were assigned by non-probabilistic randomisation to an instructor group (IG; 7 subjects), and to a student group (AG; 11 subjects). The recording of the parameters indicated corresponds to the emergency situations described above. Data collection was made in three different moments: Take-off: it starts after reading the checklist until the engine fault is resolved. Flight: during manoeuvres characterised by the recovery of abnormal positions. Landing: where the pilot performs the landing manoeuvre, with the loss of spatial situation.

Official Title
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Analysis of Heart Rate Variability During Emergency Flight Simulator Missions in Fighter Pilots

Conditions
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Heart Rate Variability, Autonomic Nervous System

Intervention / Treatment
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* Device: Analysis of heart rate variability


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pilots who had the status of instructor or student assigned at the time of assessment to the ALA 23 district of the Talavera la Real Air Base of the Ministry of Defense of the Government of Spain (Badajoz). Exclusion Criteria: Any uncontrolled neurological or cardiac disorder. Being involved in ongoing medical-legal conflicts.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Instructors group<br>Group of flight instructors at the reactor school. | Device: Analysis of heart rate variability<br>* The HR HRV interval of the heartbeat (variations in the time interval between beats) was used as a measure of autonomous modulation, and the Firstbeat Bodyguard monitor (Firstbeat Technologies, Jyväskylä, Finland) was used to record HRV data during the session with emergency situations in the flight simulator. Data was downloaded from the devices to a computer using Firstbeat Uploader software (Firstbeat Technologies), and all R-R interval series were imported into the Kubios software package (University of Eastern Finland, Kuopio, Finland). To calculate the autonomous equilibrium, the commonly used HRV method based on the Poincaré graph was used (Brennan et al., 2001; Mourot et al., 2004).<br>|
| Students group<br>Group of students at the reactor school. | Device: Analysis of heart rate variability<br>* The HR HRV interval of the heartbeat (variations in the time interval between beats) was used as a measure of autonomous modulation, and the Firstbeat Bodyguard monitor (Firstbeat Technologies, Jyväskylä, Finland) was used to record HRV data during the session with emergency situations in the flight simulator. Data was downloaded from the devices to a computer using Firstbeat Uploader software (Firstbeat Technologies), and all R-R interval series were imported into the Kubios software package (University of Eastern Finland, Kuopio, Finland). To calculate the autonomous equilibrium, the commonly used HRV method based on the Poincaré graph was used (Brennan et al., 2001; Mourot et al., 2004).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Root Mean Square of the Successive Differences (RMSSD) | It indicates the degree of activation of the Parasympathetic Nervous System on the cardiovascular system. It is obtained from the square root of the mean value of the sum of the squared differences of all successive RR intervals. This parameter reports the short-term variations of the RR intervals. It is directly associated with short-term variability. | 1 week | 
| Stress Score | It is an index described by Naranjo-Orellana et al. to facilitate physiological interpretation of Poincaré plot. It is expressed as the inverse of the SD2 diameter multiplied by 1000 and is considered directly proportional to the sympathetic activity in the sinus node. | 1 week | 
| Sympathetic/parasympathetic ratio (S/PS) | It is also described by Naranjo-Orellana et al., S/PS is expressed as the quotient of SS and SD1, and it is considered to reflect autonomic balance - that is, the relationship between sympathetic and parasympathetic activity | 1 week | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Standard Deviation 1 (SD1) | It indicates the sensitivity of short-term variability in HRV non-linear spectrum. It is considered an indicator of parasympathetic activity. | 1 week | 
| Standard Deviation 2 (SD2) | It is a diameter from Poincaré plot which indicates the degree of longitudinal dispersion. It is thought to reflect long-term changes in RR intervals and it is considered an inverse indicator of parasympathetic activity. | 1 week | 
| Min_HR | Minimum heart rate variability. | 1 week | 
| Max_HR | Maximum heart rate variability. | 1 week | 
| Mean_HR | It corresponds to the interval between two beats (R peaks on the ECG). | 1 week | 
| pNN50 | Percentage of consecutive RR intervals that differ by more than 50 ms from each other. A high value of pNN50 provides valuable information about high spontaneous HR. | 1 week | 
| Low Frequency Power (LF) | Situated between 0.04 and 0.15 Hz. In long-term recordings it provides us with more information about the activity of the SNS. | 1 week | 
| High Frequency Power (HF) | They are located between 0.15 and 0.4 Hz. HF is clearly related to PNS activity and has a relaxation-related effect on HR2. | 1 week | 
| Low/High Frequency ratio (HF/LF) | From low frequency and high frequency ratio of the HRV spectral analysis result we can estimate the vagal (related to relaxation and HF) and sympathetic (related to stress and LF) influence. Thus we can estimate sympathetic-vagal balance. | 1 week | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Emergency missions, Assesment, Military Health Services, heart rate variability, autonomic nervous system