Regional distributions of inspired 133Xe and single-breath washout curves were compared in six young healthy subjects for the upright and the head-down positions. The regional distributions of volumes (at 0, 25, 50, and 75% vital capacity, VC) and of 133Xe boluses inhaled at residual volume (RV) were inverted in the head-down position, thus behaving as if they were determined by gravity acting via the weight of the lung rather than by thoracicoabdominal shape adaptations. Nevertheless no mirror image was obtained. The vertical differences in regional distribution of the 133Xe RV bolus and of the volumes at 25% VC were increased in the head-down position, whereas the vertical difference in volumes at RV was decreased, indicating enhanced air trapping and sequential ventilation at low volumes. This was attributed to the effect of the increased pulmonary blood volume in the head-down posture. Accordingly the size of phase IV on the washout curves with the SF6-bolus as well as with the N2-resident gas method was increased in the head-down position.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1152/jappl.1983.54.2.361 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Neurophysiological and Cognitive Changes Induced by the Acute Head-Down Tilt.
Aerosp Med Hum Perform
January 2025
Introduction: In space, under weightlessness conditions, human brain activity is changed due to the shifting of body fluid and blood toward the cephalic region. This shifting leads to changes in cerebral hemodynamics and, consequently, neurophysiological function, which impacts mental functions like cognition and decision-making capabilities of space travelers. The present study reports the effect of acute exposure to simulated microgravity on cognitive functions and event-related potentials.
View Article and Find Full Text PDFSmartphone Thermal Imaging as an Adjunct to Identify Free Flap Perforators and Assisting Flap Design: A Pilot Study.
Laryngoscope Investig Otolaryngol
February 2025
Background: The main technique for identification of free flap perforator vessels is Doppler sonography, which is not always accurate, user dependent and affected by the patient's body habitus.
Methods: Adult patients undergoing head and neck resection and free flap reconstruction at two academic institutions were enrolled. Doppler sonography was used to identify perforators, and were marked using a skin marker.
Effects of short time -30° head-down tilt on time perception.
Perception
January 2025
Hebei Normal University, China.
Exposure to microgravity induces abnormal experiences that may affect the perception of time. Head-down tilts (HDTs) are commonly used to investigate the effects of weightlessness. A -30° HDT is considered an appropriate model to simulate the acute phase of microgravity exposure.
View Article and Find Full Text PDFNovel CAD/CAM-splint-based navigation protocol enhances intraoperative maxillary position control in orthognathic surgery: a case control study.
Head Face Med
January 2025
Department of Oral and Maxillofacial Surgery, Heinrich Heine University Hospital Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany.
Background: Virtual surgical planning for orthognathic surgery typically relies on two methods for intraoperative plan transfer: CAD/CAM occlusal splints and patient-specific implants (PSI). While CAD/CAM splints may offer limited accuracy, particularly in the vertical dimension, PSIs are constrained by higher costs and extended preparation times. Surgical navigation has emerged as a potential alternative, but existing protocols often involve invasive registration or lack transparent evaluation.
View Article and Find Full Text PDFMicrogravity and Cardiovascular Health in Astronauts: A Narrative Review.
Health Sci Rep
January 2025
Faculty of Medicine and Health Science Crewe Campus, University of Buckingham Crewe UK.
Background: Space exploration has become a major interest for scientific and medical research. With increasing duration and frequency of manned space missions, it is crucial to understand the impact of microgravity on the cardiovascular health of astronauts. We focus on this relationship by reviewing literature that explores how microgravity affects several hemodynamic parameters and cardiovascular biomarkers.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!