1
|
Mastrandrea CJ, Hedge ET, Robertson AD, Heckman GA, Ho J, Granados Unger F, Hughson RL. High-intensity exercise does not protect against orthostatic intolerance following bedrest in 55- to 65-yr-old men and women. Am J Physiol Regul Integr Comp Physiol 2023; 325:R107-R119. [PMID: 37184226 DOI: 10.1152/ajpregu.00315.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 04/20/2023] [Accepted: 05/09/2023] [Indexed: 05/16/2023]
Abstract
Prolonged bedrest provokes orthostatic hypotension and intolerance of upright posture. Limited data are available on the cardiovascular responses of older adults to head-up tilt following bedrest, with no studies examining the potential benefits of exercise to mitigate intolerance in this age group. This randomized controlled trial of head-down bedrest (HDBR) in 55- to 65-yr-old men and women investigated if exercise could avert post-HDBR orthostatic intolerance. Twenty-two healthy older adults (11 female) underwent a strict 14-day HDBR and were assigned to either an exercise (EX) or control (CON) group. The exercise intervention included high-intensity, aerobic, and resistance exercises. Head-up tilt-testing to a maximum of 15 minutes was performed at baseline (Pre-Bedrest) and immediately after HDBR (R1), as well as 6 days (R6) and 4 weeks (R4wk) later. At Pre-Bedrest, three participants did not complete the full 15 minutes of tilt. At R1, 18 did not finish, with no difference in tilt end time between CON (422 ± 287 s) and EX (409 ± 346 s). No differences between CON and EX were observed at R6 or R4wk. At R1, just 1 participant self-terminated the test with symptoms, while 12 others reported symptoms only after physiological test termination criteria were reached. Finishers on R1 protected arterial pressure with higher total peripheral resistance relative to Pre-Bedrest. Cerebral blood velocity decreased linearly with reductions in arterial pressure, end-tidal CO2, and cardiac output. High-intensity interval exercise did not benefit post-HDBR orthostatic tolerance in older adults. Multiple factors were associated with the reduction in cerebral blood velocity leading to intolerance.
Collapse
Affiliation(s)
| | - Eric T Hedge
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada
- Department of Kinesiology and Health Studies, University of Waterloo, Waterloo, Ontario, Canada
| | - Andrew D Robertson
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada
- Department of Kinesiology and Health Studies, University of Waterloo, Waterloo, Ontario, Canada
| | - George A Heckman
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada
| | - Joanne Ho
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada
| | - Federico Granados Unger
- Department of Kinesiology and Health Studies, University of Waterloo, Waterloo, Ontario, Canada
| | | |
Collapse
|
2
|
Liang Y, Mo P, Yang X, He Y, Zhang W, Zeng X, Xie L, Gao Q. Estimation of critical closing pressure using intravascular blood pressure of the common carotid artery. Med Eng Phys 2022; 102:103759. [DOI: 10.1016/j.medengphy.2022.103759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 01/01/2022] [Accepted: 01/14/2022] [Indexed: 10/19/2022]
|
3
|
Abidi S, Nili M, Serna S, Kim S, Hazlett C, Edgell H. Influence of sex, menstrual cycle, and oral contraceptives on cerebrovascular resistance and cardiorespiratory function during Valsalva or standing. J Appl Physiol (1985) 2017; 123:375-386. [PMID: 28522756 DOI: 10.1152/japplphysiol.00035.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/11/2017] [Accepted: 05/16/2017] [Indexed: 01/11/2023] Open
Abstract
Women experience orthostatic intolerance more than men, and they experience faintness more in the early follicular [i.e., low-hormone (LH)] than luteal [i.e., high-hormone (HH)] phase of the menstrual cycle. Men (n = 13, 25.8 ± 1.8 yr old) and women in the LH (days 2-5; placebo) and HH (days 18-24; high dose) phases of the menstrual cycle with (OC; n = 14, 22.0 ± 0.8 yr old) or without (NOC; n = 12, 21.8 ± 0.5 yr old) oral contraceptive (OC) use underwent the Valsalva maneuver and a supine-sit-stand protocol. Blood pressure, normalized stroke volume [stroke volume index (SVi)], cardiac output index, heart rate, end-tidal CO2, and middle cerebral artery (MCA) blood flow velocity were measured. When subjected to the Valsalva maneuver, all women had a greater increase in diastolic and mean MCA blood flow velocity than men (P ≤ 0.065), with no significant effect of menstrual cycle phase or OC use. When subjected to the supine-sit-stand protocol, men had lower MCA blood flow velocity (P < 0.038) than all women, and SVi was higher in men than in the NOC group in all postures (P < 0.011) and in the OC group in the LH phase of the menstrual cycle during standing (P = 0.010). Only men experienced higher resistance index (P < 0.001) and pulsatility index (P < 0.001) with standing. The OC group had lower end-tidal CO2 (P = 0.002) than the NOC group (P = 0.030) and men (P ≤ 0.067). SVi (P = 0.004) and cardiac output index (P = 0.008) were higher in the OC than NOC group. A tendency toward a lower mean MCA blood flow velocity (P = 0.058) and higher SVi (P = 0.059) and pulsatility index (P = 0.058) was noted in the HH than LH phase. Mean arterial pressure was higher in the OC than NOC group in the LH phase (P = 0.049) and lower in the HH than LH phase (P = 0.014). Our results indicate that cycling estrogens/progestins can influence ventilatory, cardiovascular, and/or cerebrovascular physiology.NEW & NOTEWORTHY We have found sex differences in the cerebrovascular response to the Valsalva maneuver and standing. Men have greater cerebral vasoconstriction (or women have greater cerebral vasodilation) during late phase II of the Valsalva maneuver, and the cerebrovascular resistance index increases in men, but not in women, during standing. Furthermore, our findings indicate that both the menstrual cycle phase and oral contraceptive use can influence cardiovascular function both at rest and during active standing.
Collapse
Affiliation(s)
- Syed Abidi
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Misha Nili
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Stephania Serna
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Simon Kim
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Christopher Hazlett
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Heather Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and .,Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| |
Collapse
|
4
|
Bronzwaer ASGT, Verbree J, Stok WJ, Daemen MJAP, van Buchem MA, van Osch MJP, van Lieshout JJ. The cerebrovascular response to lower-body negative pressure vs. head-up tilt. J Appl Physiol (1985) 2017; 122:877-883. [PMID: 28082333 DOI: 10.1152/japplphysiol.00797.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 11/22/2022] Open
Abstract
Lower-body negative pressure (LBNP) has been proposed as a MRI-compatible surrogate for orthostatic stress. Although the effects of LBNP on cerebral hemodynamic behavior have been considered to reflect those of orthostatic stress, a direct comparison with actual orthostasis is lacking. We assessed the effects of LBNP (-50 mmHg) vs. head-up tilt (HUT; at 70°) in 10 healthy subjects (5 female) on transcranial Doppler-determined cerebral blood flow velocity (CBFv) in the middle cerebral artery and cerebral perfusion pressure (CPP) as estimated from the blood pressure signal (finger plethysmography). CPP was maintained during LBNP but decreased after 2 min in response to HUT, leading to an ~15% difference in CPP between LBNP and HUT (P ≤ 0.020). Mean CBFv initially decreased similarly in response to LBNP and for HUT, but, from minute 3 on, the decline became ~50% smaller (P ≤ 0.029) during LBNP. The reduction in end-tidal Pco2 partial pressure (PetCO2 ) was comparable but with an earlier return toward baseline values in response to LBNP but not during HUT (P = 0.008). We consider the larger decrease in CBFv during HUT vs. LBNP attributable to the pronounced reduction in PetCO2 and to gravitational influences on CPP, and this should be taken into account when applying LBNP as an MRI-compatible orthostatic stress modality.NEW & NOTEWORTHY Lower-body negative pressure (LBNP) has the potential to serve as a MRI-compatible surrogate of orthostatic stress but a comparison with actual orthostasis was lacking. This study showed that the pronounced reduction in end-tidal Pco2 together with gravitational effects on the brain circulation lead to a larger decline in cerebral blood flow velocity in response to head-up tilt than during lower-body negative pressure. This should be taken into account when employing lower-body negative pressure as MRI-compatible alternative to orthostatic stress.
Collapse
Affiliation(s)
- Anne-Sophie G T Bronzwaer
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Jasper Verbree
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Wim J Stok
- Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Mat J A P Daemen
- Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; and
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Johannes J van Lieshout
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; .,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Medical Research Center/Arthritis Research United Kingdom Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, United Kingdom
| |
Collapse
|
5
|
Magdalena K, Czosnyka M, Diehl RR, Haubrich C. The Interaction Between Heart Systole and Cerebral Circulation During Lower Body Negative Pressure Test. ACTA NEUROCHIRURGICA. SUPPLEMENT 2016; 122:137-41. [PMID: 27165894 DOI: 10.1007/978-3-319-22533-3_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The time constant (τ[s]) estimates how fast the arterial part of the cerebrovascular bed fills with blood volume during the cardiac cycle, whereas a product of τ and heart rate (HR) (τ*HR[%]) assesses how this period of arterial filling is related to an entire heart cycle. In this study we aimed to investigate cerebral hemodynamics using τ and τ*HR during a progressive lower body negative pressure (LBNP) test.Transcranial Doppler cerebral blood flow velocity (CBFV), Finapres arterial blood pressure (ABP), and HR, along with end-tidal CO2, were simultaneously recorded in 38 healthy volunteers during an LBNP test. The τ was estimated using mathematical transformation of ABP and CBFV pulse waveforms. After a gradual shortening of τ from baseline (0.20 ± 0.06 s) to maximal LBNP before the onset of presyncope (0.15 ± 0.05 s), we observed a significant increase in τ at presyncope (0.24 ± 0.15 s; p = 0.0001). In the course of LBNP, the τ*HR did not significantly change from baseline (25.6 ± 5.7 % vs 26.6 ± 8.9 %, p = n.s.) except for presyncope, when it increased to 40.4 ± 21.1 % (p < 0.000001). Because the time needed to fill the arterial part of the cerebrovascular bed with blood is prolonged during presyncope, an increased part of the heart cycle seems to be spent on the cerebral blood supply.
Collapse
Affiliation(s)
- Kasprowicz Magdalena
- Department of Biomedical Engineering, Wroclaw University of Technology, Plac Grunwaldzki 13 (D1), Wroclaw, 50-377, Poland.
| | - Marek Czosnyka
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Rolf R Diehl
- Department of Neurology, Alfried-Krupp-Krankenhaus, Essen, Germany
| | | |
Collapse
|
6
|
Mündel T, Perry BG, Ainslie PN, Thomas KN, Sikken ELG, Cotter JD, Lucas SJE. Postexercise orthostatic intolerance: influence of exercise intensity. Exp Physiol 2015; 100:915-25. [DOI: 10.1113/ep085143] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/29/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Toby Mündel
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| | - Blake G. Perry
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health; School of Health and Exercise Sciences, University of British Columbia; Okanagan British Columbia Canada
- Department of Physiology; University of Otago; Dunedin New Zealand
| | - Kate N. Thomas
- School of Physical Education, Sport and Exercise Sciences; University of Otago; Dunedin New Zealand
- Department of Surgical Sciences; University of Otago; Dunedin New Zealand
| | - Elisabeth L. G. Sikken
- Department of Physiology; University of Otago; Dunedin New Zealand
- Department of Physiology; Radboud University Nijmegen Medical Centre; The Netherlands
| | - James D. Cotter
- School of Physical Education, Sport and Exercise Sciences; University of Otago; Dunedin New Zealand
| | - Samuel J. E. Lucas
- Department of Physiology; University of Otago; Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences; College of Life and Environmental Sciences, University of Birmingham; UK
| |
Collapse
|
7
|
Yang C, Gao Y, Greaves DK, Villar R, Beltrame T, Fraser KS, Hughson RL. Prior head-down tilt does not impair the cerebrovascular response to head-up tilt. J Appl Physiol (1985) 2015; 118:1356-63. [PMID: 25749443 DOI: 10.1152/japplphysiol.00871.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 02/26/2015] [Indexed: 11/22/2022] Open
Abstract
The hypothesis that cerebrovascular autoregulation was not impaired during head-up tilt (HUT) that followed brief exposures to varying degrees of prior head-down tilt (HDT) was tested in 10 healthy young men and women. Cerebral mean flow velocity (MFV) and cardiovascular responses were measured in transitions to a 60-s period of 75° HUT that followed supine rest (control) or 15 s HDT at -10°, -25°, and -55°. During HDT, heart rate (HR) was reduced for -25° and -55°, and cardiac output was lower at -55° HDT. MFV increased during -10° HDT, but not in the other conditions even though blood pressure at the middle cerebral artery (BPMCA) increased. On the transition to HUT, HR increased only for -55° condition, but stroke volume and cardiac output transiently increased for -25° and -55°. Total peripheral resistance index decreased in proportion to the magnitude of HDT and recovered over the first 20 s of HUT. MFV was significantly less in all HDT conditions compared with the control in the first 5-s period of HUT, but it recovered quickly. An autoregulation correction index derived from MFV recovery relative to BPMCA decline revealed a delay in the first 5 s for prior HDT compared with control but then a rapid increase to briefly exceed control after -55° HDT. This study showed that cerebrovascular autoregulation is modified by but not impaired by brief HDT prior to HUT and that cerebral MFV recovered quickly and more rapidly than arterial blood pressure to protect against cerebral hypoperfusion and potential syncope.
Collapse
Affiliation(s)
- Changbin Yang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Yuan Gao
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, China; and
| | - Danielle K Greaves
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Rodrigo Villar
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Thomas Beltrame
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Katelyn S Fraser
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| |
Collapse
|
8
|
Robertson AD, Edgell H, Hughson RL. Assessing cerebrovascular autoregulation from critical closing pressure and resistance area product during upright posture in aging and hypertension. Am J Physiol Heart Circ Physiol 2014; 307:H124-33. [PMID: 24858843 DOI: 10.1152/ajpheart.00086.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Static cerebral autoregulation (sCA) is believed to be resistant to aging and hypertensive pathology. However, methods to characterize autoregulation commonly rely on beat-by-beat mean hemodynamic measures and do not consider within-beat pulse wave characteristics that are impacted by arterial stiffening. We examined the role of critical closing pressure (CrCP) and resistance area product (RAP), two measures derived from the pulse wave, across supine lying, sitting, and standing postures in young adults, normotensive older adults, and older adults with controlled and uncontrolled hypertension (N = 80). Traditional measures of sCA, using both intracranial and extracranial methods, indicated similar efficiency across all groups, but within-beat measures suggested different mechanisms of regulation. At rest, RAP was increased in hypertension compared with young adults (P < 0.001), but CrCP was similar. In contrast, the drop in CrCP was the primary regulator of change in cerebrovascular resistance upon adopting an upright posture. Both CrCP and RAP demonstrated group-by-posture interaction effects (P < 0.05), with older hypertensive adults exhibiting a rise in RAP that was absent in other groups. The posture-related swings in CrCP and RAP were related to changes in both the pulsatile and mean components of arterial pressure, independent of age, cardiac output, and carbon dioxide. Group-by-posture differences in pulse pressure were mediated in part by an attenuated heart rate response in older hypertensive adults (P = 0.002). Examination of pulsatile measures in young, elderly, and hypertensive adults identified unique differences in how cerebral blood flow is regulated in upright posture.
Collapse
Affiliation(s)
- Andrew D Robertson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Heather Edgell
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
| |
Collapse
|
9
|
Immink RV, Pott FC, Secher NH, van Lieshout JJ. Hyperventilation, cerebral perfusion, and syncope. J Appl Physiol (1985) 2013; 116:844-51. [PMID: 24265279 DOI: 10.1152/japplphysiol.00637.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review summarizes evidence in humans for an association between hyperventilation (HV)-induced hypocapnia and a reduction in cerebral perfusion leading to syncope defined as transient loss of consciousness (TLOC). The cerebral vasculature is sensitive to changes in both the arterial carbon dioxide (PaCO2) and oxygen (PaO2) partial pressures so that hypercapnia/hypoxia increases and hypocapnia/hyperoxia reduces global cerebral blood flow. Cerebral hypoperfusion and TLOC have been associated with hypocapnia related to HV. Notwithstanding pronounced cerebrovascular effects of PaCO2 the contribution of a low PaCO2 to the early postural reduction in middle cerebral artery blood velocity is transient. HV together with postural stress does not reduce cerebral perfusion to such an extent that TLOC develops. However when HV is combined with cardiovascular stressors like cold immersion or reduced cardiac output brain perfusion becomes jeopardized. Whether, in patients with cardiovascular disease and/or defect, cerebral blood flow cerebral control HV-induced hypocapnia elicits cerebral hypoperfusion, leading to TLOC, remains to be established.
Collapse
Affiliation(s)
- R V Immink
- Laboratory for Clinical Cardiovascular Physiology, Department of Anatomy, Embryology, and Physiology, AMC Center for Heart Failure Research, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
| | | | | | | |
Collapse
|
10
|
Pancheva AV, Panchev VS, Pancheva MV. Cerebral blood flow is governed by the capillary pumps driven by electricity of neurons and their heat and CO2 production. Hammock posture is the optimal one. J Appl Physiol (1985) 2013; 114:1121. [PMID: 23588544 DOI: 10.1152/japplphysiol.00192.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
11
|
Zuj KA, Hughson RL. Reply to Pancheva, Panchev, and Pancheva. J Appl Physiol (1985) 2013; 114:1122. [DOI: 10.1152/japplphysiol.00249.2013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Kathryn A. Zuj
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Richard L. Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|