Abstract
Lower body negative pressure (LBNP) is a method derived from space medicine, which in recent years has been increasingly used by clinicians to assess the efficiency of the cardiovascular regulatory mechanisms. LBNP with combined tilt testing is considered as an effective form of training to prevent orthostatic intolerance. We have developed a prototype system comprising a tilt table and LBNP chamber, and tested it in the context of the feasibility of the device for assessing the pilots’ efficiency. The table allows for controlled tilting in the range from −45 to +80° at the maximum change rate of 45°/s. The LBNP value can smoothly be adjusted down to −100 mmHg at up to 20 mmHg/s. 17 subjects took part in the pilot study. A 24-minute scenario included −100 mmHg supine LBNP, head up tilt (HUT) and −60 mmHg LBNP associated with HUT, separated by resting phases. The most noticeable changes were observed in stroke volume (SV). During supine LBNP, HUT and the combined stimulus, a decrease of the SV value by 20%, 40% and below 50%, respectively, were detected. The proposed system can map any pre-programed tilt and LBNP profiles, and the pilot study confirmed the efficiency of performing experimental procedures.
Highlights
Development and evaluation of a novel system for inducing orthostatic challenge by tilt tests and lower body negative pressure
An Lower body negative pressure (LBNP) chamber integrated with a tilt table was constructed at the Military Institute of Aviation Medicine, Poland, and the preliminarily data were presented[17]
In order for the device to be used both for carrying out selection procedures and researching clinical aspects, the tilt table must meet two main requirements:
Summary
Development and evaluation of a novel system for inducing orthostatic challenge by tilt tests and lower body negative pressure. Lower body negative pressure (LBNP) is a method derived from space medicine, which in recent years has been increasingly used by clinicians to assess the efficiency of the cardiovascular regulatory mechanisms. The adverse symptoms of +Gz acceleration are intensified if the positive stimulus is preceded by −Gz acceleration, i.e. a push-pull effect occurs[7] The literature explains this increased regulatory response through the significant contribution of sympathetic activity[8]. A list of states deviating from the Earthly gravity is complemented by weightlessness and microgravity, i.e. zero- and near zero-gravity states, respectively These aspects are mainly researched in the context of space missions during which, promptly upon entering weightlessness, blood shifts toward the head[9]. Increasing the body tolerance to +Gz and −Gz accelerations and for counteracting the disadvantageous effects of weightlessness are of fundamental meaning in space and aviation medicine
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