Related Experiment Video
Updated: Aug 7, 2026

Tilt Testing with Combined Lower Body Negative Pressure: a "Gold Standard" for Measuring Orthostatic Tolerance
Published on: March 21, 2013
Maximal inspiratory and expiratory mouth pressures in sitting and half-lying positions in normal subjects
1Department of Physiotherapy, University of Queensland, St. Lucia, Australia.
Abstract:
Maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures were measured in seven normal adults in both sitting and half-lying positions on 2 days. Analysis of variance did not reveal significant differences between measurements made in the two positions for either PImax or PEmax. Measurements were repeatable and the results obtained in both positions were pooled. The coefficient of variation of PImax was 4.7% between-trials and 10.3% between-days, and those for PEmax were 3.4% and 4.4%, respectively. It is suggested that measurements of PImax and PEmax made in the half-lying position after thoracic surgery can be compared to pre-operative values which are commonly obtained in sitting without any influence from a positional effect. Details of the methodology to improve the reliability of the respiratory mouth pressures technique are discussed.
Related Concept Videos
Sites for measuring blood pressure
The Brachial Artery: Primary Site for Blood Pressure Measurement
Blood Pressure
Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Pulmonary Ventilation: Inhalation
Boyle's law becomes particularly pertinent when examining respiratory...
Mechanical Ventilation I: Indication and Settings
Mechanical Ventilation III: Noninvasive Ventilation
Noninvasive Positive-Pressure Ventilation (NIPPV)

