Evaluation of the ORTHO-LBNP System

Hypoxia Clinical Trial

— ORTHO-LBNP  

Official title:

Evaluation of a Prototype System for Generating Conditions of Orthostatic Hypotension and Blood Pooling in the Lower Body

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT03354234
• Other study ID #: ORTHO-LBNP_01/2017
• Status: Completed
• Phase: N/A
• Start date: January 2, 2017
• Est. completion date: February 17, 2018

Study information

• Verified date: May 2018
• Source: Military Institute of Aviation Medicine
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

The pilot study aims to evaluate a prototype system that enables military pilots to train under conditions of orthostatic hypotension and ischemic hypoxia. Both of these phenomena are experienced by aircraft crews of mainly highly maneuverable aircraft, and their syndromes include loss of color vision, loss of peripheral vision, blackout and finally G-induced loss of consciousness (G-LOC). A motorized tilt table to generate orthostatic (ORTHO) stress combined with an automatically controlled lower body negative pressure (LBNP) chamber to extort pooling of blood in the lower extremities has been developed in order to obtain new knowledge on counteracting the above-mentioned effects and minimizing the risk of their occurrence. This will help optimize the selection procedures of candidates with the best physiological predispositions to work as military pilots. The system is equipped with modules for monitoring biomedical parameters of a subject, including cerebral oxygenation, which ensures their safety and provides a source of data for performing advanced analyses. The ORTHO-LBNP system has been subjected to comprehensive laboratory tests and after a successful testing is ready for a pilot study involving pilots and/or cadets of the Polish Air Force Academy (PAFA). It is anticipated that new indicators will be proposed to enable an objective assessment of the predispositions to pursue a military pilot career. The prototype system can be easily adaptable to the needs of clinical and sports medicine as well as rehabilitation.

Description:

The pilot study consists of two research scenarios, in which two different sequences of the interventions taking the form of the pre-programmed tilt and LBNP profiles are to be investigated.

1. Scenario I is designed to initially verify the potential impact of the prototype system on the human body. For this purpose, only basic tilt and LBNP stimuli of relatively slowly increasing intensities will be used, and the group of subjects will include only subjects with flight experience. Up to 20 PAFA cadets shortly before graduation, including women and men, will be involved in the pilot study (experimental arm 1). The subjects will be healthy, aged between 20 and 30 years old. Scenario I will take almost 24 min.

2. Scenario II is to compare subjects with and without flight experience using rapid tilt and LBNP stimuli as well as a push-pull stimulus. Up to 30 subjects including up to 15 pilots, i.e., flight school adepts shortly after graduation and/or PAFA cadets shortly before graduation, and up to 15 students of the Aviation High School in Dęblin, Poland, including women and men will be involved in the study (experimental arm 2). The subjects will be healthy, aged between 18 and 30 years old. The students of the Aviation High School will participate in the study as a reference group, without flight experience. Scenario II will take 16 min.

The pilot study will be carried out in an isolated room in the presence of a physician (physiologist), a paramedic and an ORTHO-LBNP system operator. The paramedic will prepare the subject for the study by placing on his/her body electrodes and measuring sensors that will be removed after completion of the study. The subject will be asked to close his/her eyes during the tests and to place his/her hands on the rest. In order to cause the least disturbance, no conversation will be held with the subject. Only if disturbing symptoms will occur, will the subject immediately report this to the personnel. The physician will systematically be observing the subject's cardiogram, his/her HR, continuous non-invasive arterial pressure (CNAP) wave, and systolic and diastolic blood pressure (SBP and DBP, respectively) in comparison with the changing tilt of the table and negative pressure in the chamber. Any time, at the request of the subject or on the instruction of the physician, the operator will interrupt the tests. The tilt table then will return to the Trendelenburg position if interruption occur during HUT and/or LBNP stimuli, or horizontal position if interruption occur during HDT stimulus. At the same time atmospheric pressure will be resumed in the chamber.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 46
• Est. completion date: February 17, 2018
• Est. primary completion date: February 17, 2018
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 30 Years

Eligibility

Inclusion Criteria:

• Pilots or cadets with flight experience

• Candidates for pilots without flight experience

• None alcohol 24 hours prior to the study

• Written informed consent

Exclusion Criteria:

• Subjects with cardiovascular disorders

Related Conditions & MeSH terms

• Hypotension
• Hypotension, Orthostatic
• Hypoxia
• Ischemia
• Orthostatic Hypotension

Intervention

Other:
• Head up tilt (HUT)
Model of -Gz: HUT up to 75 degrees (maximum)
• Lower body negative pressure (LBNP)
Model of -Gz: LBNP down to -100 mmHg (maximum)
• Head down tilt (HDT)
Model of +Gz: HDT down to -30 degrees (maximum)

Device:
• Tilt table
Range of tilt angles: -45° to +80°, rate of tilt changes: up to 45°/s
• LBNP chamber
Range of generated underpressure: 0 to -100 mmHg, rate of underpressure changes: up to 20 mmHg/s

Locations

Country	Name	City	State
Poland	Military Institute of Aviation Medicine	Warszawa

Sponsors (5)

Lead Sponsor	Collaborator
Military Institute of Aviation Medicine	ETC-PZL Aerospace Industries Sp. z o.o., Institute of Medical Technology and Equipment, Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Polish Air Force Academy

Country where clinical trial is conducted

Poland, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	HR	Heart rate in beats per minute	24 minutes (scenario I)
Primary	IBI	Inter-beat interval in seconds	24 minutes (scenario I)
Primary	SBP	Systolic blood pressure in millimeters of mercury	24 minutes (scenario I)
Primary	DBP	Diastolic blood pressure in millimeters of mercury	24 minutes (scenario I)
Primary	MAP	Mean arterial pressure in millimeters of mercury	24 minutes (scenario I)
Primary	SV	Stroke volume in milliliters	24 minutes (scenario I)
Primary	CO	Cardiac output in liters per minute	24 minutes (scenario I)
Primary	LVET	Left ventricular ejection time in milliseconds	24 minutes (scenario I)
Primary	RPP	Rate pressure product in millimeters of mercury	24 minutes (scenario I)
Primary	TPR	Total peripheral resistance in medical units	24 minutes (scenario I)
Secondary	Z0_T	Base transthoracic impedance in ohms	16 minutes (scenario II)
Secondary	dZ/dt_T	First derivative of transthoracic impedance in ohms per second	16 minutes (scenario II)
Secondary	Z0_H	Base transcephalic impedance in ohms	16 minutes (scenario II)
Secondary	dZ/dt_H	First derivative of transcephalic impedance in ohms per second	16 minutes (scenario II)
Secondary	?C_HbO2	Changes in oxygenated hemoglobin in micromolars	16 minutes (scenario II)
Secondary	?C_Hb	Changes in deoxygenated hemoglobin in micromolars	16 minutes (scenario II)
Secondary	?C_tot	Changes in total hemoglobin in micromolars	16 minutes (scenario II)