Cardiovascular responses to short-term head-down positioning in healthy young and older adults

• Published in: Physiotherapy research international : the journal for researchers and clinicians in physical therapy Vol. 10; no. 1; pp. 32 - 47
• Main Authors: Naylor, Justine M, Chow, Chin-Moi, McLean, Anthony S, Heard, Robert C, Avolio, Albert
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.03.2005
• Subjects: Adult; Age Factors; Aged; Baroreflex - physiology; Blood Pressure; cardiovascular; chest physiotherapy; head-down tilt; Head-Down Tilt - physiology; Heart Rate; Hemodynamics; Humans; Male; Middle Aged; Myocardium - metabolism; Oxygen - metabolism; Oxygen Consumption; postural drainage; sphygmocardiography
• ISSN: 1358-2267; 1471-2865
• DOI: 10.1002/pri.22

Background and Purpose. Isolated head‐down postural drainage is assumed to acutely load the cardiovascular system. Consequently, it is considered a relative contraindication in the presence of severe cardiovascular disease. Evidence demonstrating that the head‐down manoeuvre as used by physiotherapists does significantly load the cardiovascular system is lacking. The present study documents the cardiovascular responses to short‐term 30° head‐down positioning in healthy subjects. The results are a point of reference for respiratory patients with and without cardiovascular disease. Method. A quasi‐experimental research design was used, with multiple measurements obtained at rest (long sitting) and in the head‐down position. Twenty‐one young subjects (mean age 25 years (standard deviation, (SD) 3 years)) and 19 older subjects (mean age 66 years (SD 6 years)) were studied. Applanation tonometry and sphygmocardiography were used to measure temporal and pressure variables, and indices that estimate myocardial work and coronary blood flow. Results. Absolute differences existed between the two age groups for all variables at rest (p< 0.001). No age–time interaction was observed for any variable in the head‐down position (p>0.05). Serial measures in the head‐down position did not vary across time (p>0.05). Small (<9%) but significant (p ≤ 0.02) decreases in heart rate, relative diastolic duration, mean arterial blood pressure and diastolic time indices, and small (<12%) but significant (p ≤ 0.002) increases in cardiac cycle time, ejection duration (relative and absolute) and absolute diastolic duration were observed in the head‐down position compared with rest. A small (9%) but significant (p< 0.001) fall in the sub‐endocardial viability ratio occurred in the head‐down position. Conclusion. The findings have little consequence in health, but they suggest that head‐down postural drainage may be of concern for chest physiotherapy recipients with reduced cardiac reserve or impaired baroreflex function. Copyright © 2005 Whurr Publishers Ltd.