Age alters the cardiovascular response to direct passive heating

Christopher T. Minson, Stacey L. Wladkowski, Anthony F. Cardell, James Anthony Pawelczyk, William Lawrence Kenney, Jr.

Research output: Contribution to journalArticle

152 Citations (Scopus)

Abstract

During direct passive heating in young men, a dramatic increase in skin blood flow is achieved by a rise in cardiac output (Q(c)) and redistribution of flow from the splanchnic and renal vascular beds. To examine the effect of age on these responses, seven young (Y; 23 ± 1 yr) and seven older (O; 70 ± 3 yr) men were passively heated with water-perfused suits to their individual limit of thermal tolerance. Measurements included heart rate (HR), Q(c) (by acetylene rebreathing), central venous pressure (via peripherally inserted central catheter), blood pressures (by brachial auscultation), skin blood flow (from increases in forearm blood flow by venous occlusion plethysmography), splanchnic blood flow (by indocyanine green clearance), renal blood flow (by p-aminohippurate clearance), and esophageal and mean skin temperatures. Q(c) was significantly lower in the older than in the young men (11.1 ± 0.7 and 7.4 ± 0.21/min in Y and O, respectively, at the limit of thermal tolerance; P < 0.05), despite similar increases in esophageal and mean skin temperatures and time to reach the limit of thermal tolerance. A lower stroke volume (99 ± 7 and 68 ± 4 ml/beat in Y and O, respectively, P < 0.05), most likely due to an attenuated increase in inotropic function during heating, was the primary factor for the lower Q(c) observed in the older men. Increases in HR were similar in the young and older men; however, when expressed as a percentage of maximal HR, the older men relied on a greater proportion of their chronotropic reserve to obtain the same HR response (62 ± 3 and 75 ± 4% maximal HR in Y and O, respectively, P < 0.05). Furthermore, the older men redistributed less blood flow from the combined splanchnic and renal circulations at the limit of thermal tolerance (960 ± 80 and 720 ± 100 ml/min in Y and O, respectively, P < 0.05). As a result of these combined attenuated responses, the older men had a significantly lower increase in total blood flow directed to the skin.

Original languageEnglish (US)
Pages (from-to)1323-1332
Number of pages10
JournalJournal of Applied Physiology
Volume84
Issue number4
StatePublished - Apr 1998

Fingerprint

Heating
Heart Rate
Viscera
Skin Temperature
Renal Circulation
Skin
Splanchnic Circulation
p-Aminohippuric Acid
Auscultation
Acetylene
Central Venous Pressure
Indocyanine Green
Plethysmography
Forearm
Cardiac Output
Stroke Volume
Blood Vessels
Arm
Catheters
Blood Pressure

All Science Journal Classification (ASJC) codes

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Minson, Christopher T. ; Wladkowski, Stacey L. ; Cardell, Anthony F. ; Pawelczyk, James Anthony ; Kenney, Jr., William Lawrence. / Age alters the cardiovascular response to direct passive heating. In: Journal of Applied Physiology. 1998 ; Vol. 84, No. 4. pp. 1323-1332.
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Age alters the cardiovascular response to direct passive heating. / Minson, Christopher T.; Wladkowski, Stacey L.; Cardell, Anthony F.; Pawelczyk, James Anthony; Kenney, Jr., William Lawrence.

In: Journal of Applied Physiology, Vol. 84, No. 4, 04.1998, p. 1323-1332.

Research output: Contribution to journalArticle

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T1 - Age alters the cardiovascular response to direct passive heating

AU - Minson, Christopher T.

AU - Wladkowski, Stacey L.

AU - Cardell, Anthony F.

AU - Pawelczyk, James Anthony

AU - Kenney, Jr., William Lawrence

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N2 - During direct passive heating in young men, a dramatic increase in skin blood flow is achieved by a rise in cardiac output (Q(c)) and redistribution of flow from the splanchnic and renal vascular beds. To examine the effect of age on these responses, seven young (Y; 23 ± 1 yr) and seven older (O; 70 ± 3 yr) men were passively heated with water-perfused suits to their individual limit of thermal tolerance. Measurements included heart rate (HR), Q(c) (by acetylene rebreathing), central venous pressure (via peripherally inserted central catheter), blood pressures (by brachial auscultation), skin blood flow (from increases in forearm blood flow by venous occlusion plethysmography), splanchnic blood flow (by indocyanine green clearance), renal blood flow (by p-aminohippurate clearance), and esophageal and mean skin temperatures. Q(c) was significantly lower in the older than in the young men (11.1 ± 0.7 and 7.4 ± 0.21/min in Y and O, respectively, at the limit of thermal tolerance; P < 0.05), despite similar increases in esophageal and mean skin temperatures and time to reach the limit of thermal tolerance. A lower stroke volume (99 ± 7 and 68 ± 4 ml/beat in Y and O, respectively, P < 0.05), most likely due to an attenuated increase in inotropic function during heating, was the primary factor for the lower Q(c) observed in the older men. Increases in HR were similar in the young and older men; however, when expressed as a percentage of maximal HR, the older men relied on a greater proportion of their chronotropic reserve to obtain the same HR response (62 ± 3 and 75 ± 4% maximal HR in Y and O, respectively, P < 0.05). Furthermore, the older men redistributed less blood flow from the combined splanchnic and renal circulations at the limit of thermal tolerance (960 ± 80 and 720 ± 100 ml/min in Y and O, respectively, P < 0.05). As a result of these combined attenuated responses, the older men had a significantly lower increase in total blood flow directed to the skin.

AB - During direct passive heating in young men, a dramatic increase in skin blood flow is achieved by a rise in cardiac output (Q(c)) and redistribution of flow from the splanchnic and renal vascular beds. To examine the effect of age on these responses, seven young (Y; 23 ± 1 yr) and seven older (O; 70 ± 3 yr) men were passively heated with water-perfused suits to their individual limit of thermal tolerance. Measurements included heart rate (HR), Q(c) (by acetylene rebreathing), central venous pressure (via peripherally inserted central catheter), blood pressures (by brachial auscultation), skin blood flow (from increases in forearm blood flow by venous occlusion plethysmography), splanchnic blood flow (by indocyanine green clearance), renal blood flow (by p-aminohippurate clearance), and esophageal and mean skin temperatures. Q(c) was significantly lower in the older than in the young men (11.1 ± 0.7 and 7.4 ± 0.21/min in Y and O, respectively, at the limit of thermal tolerance; P < 0.05), despite similar increases in esophageal and mean skin temperatures and time to reach the limit of thermal tolerance. A lower stroke volume (99 ± 7 and 68 ± 4 ml/beat in Y and O, respectively, P < 0.05), most likely due to an attenuated increase in inotropic function during heating, was the primary factor for the lower Q(c) observed in the older men. Increases in HR were similar in the young and older men; however, when expressed as a percentage of maximal HR, the older men relied on a greater proportion of their chronotropic reserve to obtain the same HR response (62 ± 3 and 75 ± 4% maximal HR in Y and O, respectively, P < 0.05). Furthermore, the older men redistributed less blood flow from the combined splanchnic and renal circulations at the limit of thermal tolerance (960 ± 80 and 720 ± 100 ml/min in Y and O, respectively, P < 0.05). As a result of these combined attenuated responses, the older men had a significantly lower increase in total blood flow directed to the skin.

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