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Rhim G, Kim MJ. Effect of the early diastolic blood pressure response to the head-up tilt test on the recurrence of benign paroxysmal positional vertigo. PLoS One 2024; 19:e0301800. [PMID: 38696405 PMCID: PMC11065201 DOI: 10.1371/journal.pone.0301800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 03/23/2024] [Indexed: 05/04/2024] Open
Abstract
BACKGROUND Otolith organ acts complementarily with the autonomic nervous system to maintain blood pressure. However, the effect of blood pressure variability in the autonomic nervous system on otolith organ has not yet been determined. This study aimed to verify the hypothesis that blood pressure variability in the autonomic nervous system affects the recurrence of benign paroxysmal positional vertigo (BPPV), which is the most common disease of the vestibular organs, by using the head-up tilt test (HUTT). METHODS This study included 432 patients diagnosed with idiopathic BPPV. The follow-up period for all patients was 12 months. Age, sex, hypertension, diabetes and recurrence were analyzed. The HUTT parameters were divided into a group of patients whose average diastolic blood pressure increased in the upright position compared to supine position during the HUTT (DBP1) and a group of patients whose average diastolic blood pressure decreased in the upright position compared to supine position during the HUTT (DBP2). Model selection, general loglinear analysis, and logit loglinear analysis were performed using a hierarchically progressing loglinear analysis. RESULTS In summary, the group with increased average diastolic blood pressure (DBP1) showed a higher tendency for BPPV recurrence compared to the group with decreased diastolic blood pressure (DBP2) in the upright position during the HUTT, although the difference was not statistically significant (p = 0.080). However, in males, the DBP1 group demonstrated a significantly higher recurrence rate of BPPV than the DBP2 group during the HUTT (95% CI, -20.021 to -16.200; p < 0.001). CONCLUSIONS It is presumed that poor autonomic nervous system response through vestibulosympathetic reflex maintains elevated diastolic blood pressure in the upright position during the HUTT. This variability is assumed to affect the recurrence of BPPV.
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Affiliation(s)
- Guil Rhim
- Department of Otorhinolaryngology, One Otorhinolaryngology Clinic, Paju, Republic of Korea
| | - Moon Jung Kim
- Department of Laboratory Medicine, Myunggok Medical Research Center, Konyang University College of Medicine, Daejeon, Republic of Korea
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2
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Kato T, Konishi T, Kurazumi T, Ogawa Y, Iwasaki K. Steady-state cerebral blood flow and dynamic cerebral autoregulation during neck flexion and extension in seated healthy young adults. Physiol Rep 2023; 11:e15622. [PMID: 36808705 PMCID: PMC9938106 DOI: 10.14814/phy2.15622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 02/05/2023] [Accepted: 02/06/2023] [Indexed: 02/20/2023] Open
Abstract
Neck flexion and extension show differences in various physiological factors, such as sympathetic nerve activity and intracranial pressure (ICP). We hypothesized that differences would exist in steady-state cerebral blood flow and dynamic cerebral autoregulation between neck flexion and extension in seated, healthy young adults. Fifteen healthy adults were studied in the sitting position. Data were collected during neck flexion and extension in random order for 6 min each on the same day. Arterial pressure at the heart level was measured using a cuff sphygmomanometer. Mean arterial pressure at the middle cerebral artery (MCA) level (MAPMCA ) was calculated by subtracting the hydrostatic pressure difference between heart and MCA levels from mean arterial pressure at the heart level. Non-invasive cerebral perfusion pressure (nCPP) was estimated as the MAPMCA minus the non-invasive ICP as determined from transcranial Doppler ultrasonography. Waveforms of arterial pressure in the finger and blood velocity in the MCA (MCAv) were obtained. Dynamic cerebral autoregulation was evaluated by transfer function analysis between these waveforms. The results showed that nCPP was significantly higher during neck flexion than during neck extension (p = 0.004). However, no significant differences were observed in mean MCAv (p = 0.752). Likewise, no significant differences were observed in any of the three indices of dynamic cerebral autoregulation in any frequency range. Although non-invasively estimated cerebral perfusion pressure was significantly higher during neck flexion than during neck extension, no differences in steady-state cerebral blood flow or dynamic cerebral autoregulation were evident between neck flexion and extension in seated healthy adults.
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Affiliation(s)
- Tomokazu Kato
- Department of Social Medicine, Division of HygieneNihon University School of MedicineTokyoJapan
| | - Toru Konishi
- Department of Social Medicine, Division of HygieneNihon University School of MedicineTokyoJapan,Air Staff Office, Japan Air Self‐Defense ForceTokyoJapan
| | - Takuya Kurazumi
- Department of Social Medicine, Division of HygieneNihon University School of MedicineTokyoJapan,Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTexasUSA,Department of NeurologyUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | - Yojiro Ogawa
- Department of Social Medicine, Division of HygieneNihon University School of MedicineTokyoJapan
| | - Ken‐ichi Iwasaki
- Department of Social Medicine, Division of HygieneNihon University School of MedicineTokyoJapan
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3
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Kerkering EM, Greenlund IM, Bigalke JA, Migliaccio GCL, Smoot CA, Carter JR. Reliability of Heart Rate Variability During Stable and Disrupted Polysomnographic Sleep. Am J Physiol Heart Circ Physiol 2022; 323:H16-H23. [PMID: 35559723 DOI: 10.1152/ajpheart.00143.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heart rate variability (HRV) is commonly used within sleep and cardiovascular research, yet HRV reliability across various sleep stages remains equivocal. The present study examined the reliability of frequency- and time-domain HRV within stage II (N2), slow wave (SWS), and rapid eye movement (REM) sleep during both stable and disrupted sleep. We hypothesized that high-frequency (HF) HRV would be reliable in all three sleep stages, low-frequency (LF) HRV would be reliable during N2 and SWS, and that disrupted sleep via spontaneous cortical arousals would decrease HRV reliability. Twenty-seven participants (11 male, 16 female, 26±1 years) were equipped with laboratory polysomnography for one night. Both frequency- and time-domain HRV were analyzed in two 5-10 minute blocks during multiple stable and disrupted sleep cycles across N2, SWS and REM sleep. HF HRV was highly correlated across stable N2 (r=0.839, p<0.001), SWS (r=0.765, p<0.001) and REM (r=0.881, p<0.001). LF HRV was moderate-to-highly correlated during stable cycles of N2 sleep (r=0.694, p < 0.001), SWS, (r=0.765, p < 0.001), and REM (r=0.699, p<0.001) sleep. When stable sleep was compared with disrupted sleep, both time- and frequency-domain HRV were reliable (α>0.90, p<0.05) in N2, SWS, and REM, with the exception of LF HRV during SWS (α=0.62, p=0.089). In conclusion, time- and frequency-domain HRV demonstrated reliability across stable N2, SWS and REM sleep, and remained reliable during disrupted sleep. These findings support the use of HRV during sleep as a tool for assessing cardiovascular health and risk stratification.
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Affiliation(s)
- Emma M Kerkering
- Department of Microbiology & Cell Biology, Montana State University, Bozeman, MT, United States
| | - Ian M Greenlund
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Psychology, Montana State University, Bozeman, MT, United States
| | - Jeremy A Bigalke
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Psychology, Montana State University, Bozeman, MT, United States
| | - Gianna C L Migliaccio
- Department of Microbiology & Cell Biology, Montana State University, Bozeman, MT, United States
| | - Carl A Smoot
- Department of Microbiology & Cell Biology, Montana State University, Bozeman, MT, United States.,Department of Psychology, Montana State University, Bozeman, MT, United States
| | - Jason R Carter
- Department of Microbiology & Cell Biology, Montana State University, Bozeman, MT, United States.,Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Psychology, Montana State University, Bozeman, MT, United States
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4
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Greenlund IM, Bigalke JA, Tikkanen AL, Durocher JJ, Smoot CA, Carter JR. Evening Binge Alcohol Disrupts Cardiovagal Tone and Baroreflex Function During Polysomnographic Sleep. Sleep 2021; 44:6279273. [PMID: 34015116 DOI: 10.1093/sleep/zsab130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/23/2021] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVES Binge alcohol consumption is associated with increased cardiovascular risk. The effects of evening binge alcohol consumption (i.e., 4-5 beverages within two hours) on the vagal components of HRV and cardiovagal baroreflex sensitivity (cvBRS) during sleep remain largely equivocal. The present study examined the effects of evening binge alcohol consumption on nocturnal cardiac vagal tone and baroreflex sensitivity during stage N2, slow wave (SWS), and rapid eye movement (REM) sleep. We hypothesized that evening binge drinking would reduce HRV and cvBRS in each sleep stage. METHODS Following a familiarization night within the laboratory, twenty-three participants were examined following a night of binge alcohol consumption and a fluid control (randomized, crossover design). A quality nocturnal beat-to-beat blood pressure signal was obtained in both conditions in 16 participants (7 men, 9 women; 25±1 years). RESULTS Binge drinking reduced both the high frequency (HF) and time-domain components (i.e., pNN50 and RMSSD) of HRV in stage N2 sleep, SWS, and REM. In addition, cvBRS up-up (vagal activation) was reduced following binge alcohol consumption in stage N2 (21±3 vs. 15±3 ms/mmHg, P=0.035) and REM (15[11-28] vs. 11[9-18] ms/mmHg, P=0.009). Binge alcohol consumption reduced cvBRS down-down (vagal withdrawal) in stage N2 (23±2 vs. 14±2 ms/mmHg, P<0.001), SWS (20[14-30] vs. 14[9-17] ms/mmHg, P=0.022), and REM (14[11-24] vs. 10[7-15] ms/mmHg, P=0.006). CONCLUSIONS Evening binge alcohol consumption disrupts cardiac vagal tone and baroreflex function during nearly all sleep stages. These findings provide mechanistic insight into the potential role of binge drinking and alcohol abuse on cardiovascular risk.
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Affiliation(s)
- Ian M Greenlund
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Psychology, Montana State University, Bozeman, Montana, United States.,Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
| | - Jeremy A Bigalke
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Psychology, Montana State University, Bozeman, Montana, United States.,Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
| | - Anne L Tikkanen
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
| | - John J Durocher
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States.,Department of Biological Sciences, Purdue University Northwest, Hammond, Indiana, United States
| | - Carl A Smoot
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
| | - Jason R Carter
- Department of Health & Human Development, Montana State University, Bozeman, Montana, United States.,Department of Psychology, Montana State University, Bozeman, Montana, United States.,Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, Michigan, United States
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5
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Ahmadi H, Herat N, Alizadeh S, Button DC, Granacher U, Behm DG. Effect of an inverted seated position with upper arm blood flow restriction on measures of elbow flexors neuromuscular performance. PLoS One 2021; 16:e0245311. [PMID: 34010275 PMCID: PMC8133415 DOI: 10.1371/journal.pone.0245311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/28/2021] [Indexed: 11/20/2022] Open
Abstract
Purpose The objective of the investigation was to determine the concomitant effects of upper arm blood flow restriction (BFR) and inversion on elbow flexors neuromuscular responses. Methods Randomly allocated, 13 volunteers performed four conditions in a within-subject design: rest (control, 1-min upright position without BFR), control (1-min upright with BFR), 1-min inverted (without BFR), and 1-min inverted with BFR. Evoked and voluntary contractile properties, before, during and after a 30-s maximum voluntary contraction (MVC) exercise intervention were examined as well as pain scale. Results Inversion induced significant pre-exercise intervention decreases in elbow flexors MVC (21.1%, ηp2 = 0.48, p = 0.02) and resting evoked twitch forces (29.4%, ηp2 = 0.34, p = 0.03). The 30-s MVC induced significantly greater pre- to post-test decreases in potentiated twitch force ( ηp2 = 0.61, p = 0.0009) during inversion (↓75%) than upright (↓65.3%) conditions. Overall, BFR decreased MVC force 4.8% ( ηp2 = 0.37, p = 0.05). For upright position, BFR induced 21.0% reductions in M-wave amplitude ( ηp2 = 0.44, p = 0.04). There were no significant differences for electromyographic activity or voluntary activation as measured with the interpolated twitch technique. For all conditions, there was a significant increase in pain scale between the 40–60 s intervals and post-30-s MVC (upright<inversion, and without BFR<BFR). Conclusion The concomitant application of inversion with elbow flexors BFR only amplified neuromuscular performance impairments to a small degree. Individuals who execute forceful contractions when inverted or with BFR should be cognizant that force output may be impaired.
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Affiliation(s)
- Hamid Ahmadi
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Nehara Herat
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Shahab Alizadeh
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Duane C. Button
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Urs Granacher
- Division of Training and Movement Science, University of Potsdam, Potsdam, Germany
| | - David G. Behm
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
- * E-mail:
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6
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Prone sleeping position in infancy: Implications for cardiovascular and cerebrovascular function. Sleep Med Rev 2018; 39:174-186. [DOI: 10.1016/j.smrv.2017.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/30/2017] [Accepted: 10/09/2017] [Indexed: 01/14/2023]
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7
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White DW, Shoemaker JK, Raven PB. Methods and considerations for the analysis and standardization of assessing muscle sympathetic nerve activity in humans. Auton Neurosci 2015; 193:12-21. [PMID: 26299824 DOI: 10.1016/j.autneu.2015.08.004] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 08/01/2015] [Accepted: 08/03/2015] [Indexed: 01/20/2023]
Abstract
The technique of microneurography and the assessment of muscle sympathetic nerve activity (MSNA) are used in laboratories throughout the world. The variables used to describe MSNA, and the criteria by which these variables are quantified from the integrated neurogram, vary among studies and laboratories and, therefore, can become confusing to those starting to learn the technique. Therefore, the purpose of this educational review is to discuss guidelines and standards for the assessment of sympathetic nervous activity through the collection and analysis of MSNA. This review will reiterate common practices in the collection of MSNA, but will also introduce considerations for the evaluation and physiological inference using MSNA.
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Affiliation(s)
- Daniel W White
- The Department of Kinesiology & Nutrition, University of Illinois at Chicago, Chicago, IL, USA.
| | - J Kevin Shoemaker
- The School of Kinesiology, University of Western Ontario, London, ON, Canada
| | - Peter B Raven
- Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
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8
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Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow. Med Eng Phys 2014; 36:563-75. [DOI: 10.1016/j.medengphy.2014.02.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
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9
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Wong F, Yiallourou SR, Odoi A, Browne P, Walker AM, Horne RSC. Cerebrovascular control is altered in healthy term infants when they sleep prone. Sleep 2013; 36:1911-8. [PMID: 24293766 PMCID: PMC3825441 DOI: 10.5665/sleep.3228] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Sudden infant death syndrome (SIDS) is a leading cause of infant death, and prone sleeping is the major risk factor. Prone sleeping impairs arousal from sleep and cardiovascular control in infants at 2-3 months, coinciding with the highest risk period for SIDS. We hypothesized that prone sleeping would also alter cerebrovascular control, and aimed to test this hypothesis by examining responses of cerebral oxygenation to head-up tilts (HUTs) over the first 6 months after birth. STUDY DESIGN AND PARTICIPANTS Seventeen healthy full-term infants were studied at 2-4 weeks, 2-3 months, and 5-6 months of age using daytime polysomnography, with the additional measurements of blood pressure (BP, Finometer™, Finometer Medical Systems, The Netherlands) and cerebral tissue oxygenation index (TOI, NIRO 200, Hamamatsu Photonics KK, Japan). HUTs were performed in active sleep (AS) and quiet sleep (QS) in both prone and supine positions. RESULTS When infants slept in the prone position, a sustained increase in TOI (P < 0.05) occurred following HUTs, except in QS at 2-3 months when TOI was unchanged. BP was either unchanged or fell below baseline during the sustained TOI increase, signifying cerebro-vasodilatation. In contrast, when infants slept supine, TOI did not change after HUTs, except in QS at 2-3 and 5-6 months when TOI dropped below baseline (P < 0.05). CONCLUSIONS When infants slept in the prone position, cerebral arterial vasodilation and increased cerebral oxygenation occurred during head-up tilts, possibly as a protection against cerebral hypoxia. Absence of the vasodilatory response during quiet sleep at 2-3 months possibly underpins the decreased arousability from sleep and increased risk for sudden infant death syndrome at this age.
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Affiliation(s)
- Flora Wong
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
- Monash Newborn, Monash Medical Centre, Melbourne, Victoria, Australia
- Department of Paediatrics, Monash University, Melbourne, Victoria, Australia
| | - Stephanie R. Yiallourou
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - Alexsandria Odoi
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - Pamela Browne
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - Adrian M. Walker
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - Rosemary S. C. Horne
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
- Department of Paediatrics, Monash University, Melbourne, Victoria, Australia
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10
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Johar P, Grover V, DiSanto MC, Button DC, Behm DG. A rapid rotation to an inverted seated posture inhibits muscle force, activation, heart rate and blood pressure. Eur J Appl Physiol 2013; 113:2005-13. [PMID: 23546453 DOI: 10.1007/s00421-013-2632-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 03/19/2013] [Indexed: 10/27/2022]
Abstract
Although previous studies have demonstrated neuromuscular and cardiovascular changes with slow inversion rates, emergencies, such as overturned vehicles and helicopters can occur rapidly. The purpose of this study was to investigate changes in neuromuscular and cardiovascular responses with rapid (1 s) and slower (3 s) transitions from upright to inverted seated positions. Twenty-two subjects performed separate and concurrent unilateral elbow flexion and leg extension maximal voluntary contractions (MVCs) for 6 s in an upright seated position and when inverted with 1 and 3 s rotations. Elbow flexion and leg extension force; biceps, triceps, quadriceps and hamstrings electromyographic (EMG) activity, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured. Whether the elbow flexion or leg extension contractions occurred concurrently or individually, significant (p < 0.05) decreases in MVC force and EMG activity were found when inverted within 1 and 3 s rotations as compared to upright. Triceps and hamstrings EMG activity (p < 0.05) decreased when inverted within 1 s rotation as compared to upright. Following rotation, the maintenance of the inverted position (3-6 s timepoint) resulted in a significant (p < 0.05) increase in leg extension MVC as compared to the initial second of rotation to inversion. HR, SBP and DBP demonstrated (p < 0.001) decreases when inverted within 1 and 3 s rotations as compared to upright. In conclusion, this is the first study to show that irrespective of rotation speed, inversion inhibited neuromuscular and cardiovascular responses, similar to the more deliberate, slower rotation of previous inversion studies.
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Affiliation(s)
- Pramod Johar
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada
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11
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Paddock N, Behm D. The effect of an inverted body position on lower limb muscle force and activation. Appl Physiol Nutr Metab 2009; 34:673-80. [PMID: 19767803 DOI: 10.1139/h09-056] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Complete inversion of the body in a seated position may occur in exceptional circumstances such as in overturned vehicles and during military maneuvers, with direct consequences on health and fatalities. However, the physiological responses to this condition have not been published previously. The purpose of this study was to compare neuromuscular responses to upright and inverted seated positions. Sixteen subjects performed maximal voluntary contraction (MVC) and submaximal voluntary contraction knee extensions (25%, 50%, and 75% of MVC) under upright and inverted seated positions. Force, quadriceps activation as measured by the interpolated twitch technique, electromyographic (EMG) activity of the vastus lateralis, and semitendenosis and evoked contractile properties of the quadriceps were measured. Results demonstrated that MVC force (p = 0.01, 6.1%) and vastus lateralis EMG (p = 0.009, 29.6%) decreased in the inverted compared with the upright position. Instantaneous strength in the inverted position was 19.3% lower than in the upright position (p = 0.005). Heart rate and diastolic and systolic blood pressures were 12.4%, 9.2%, and 10.7% lower (p < 0.0001), respectively, in the inverted position. In conclusion, a seated inverted position impaired MVC force and EMG activity, which could not be attributed to evoked contractile properties. The changes in heart rate and blood pressure may suggest inversion-induced alterations to the sympathetic nervous stimulation.
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Affiliation(s)
- Natasha Paddock
- Department of Physiology, University of Manitoba, Winnipeg, MB R3E 3J7, Canada
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12
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An inverted seated posture decreases elbow flexion force and muscle activation. Eur J Appl Physiol 2009; 106:139-47. [PMID: 19214555 DOI: 10.1007/s00421-009-0999-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2009] [Indexed: 10/21/2022]
Abstract
The purpose of this study was to determine if discrepancies exist between upright and inverted seated positions in isometric maximal voluntary contraction (MVC) elbow flexor force, MVC force produced in the first 100 ms (F100), MVC rate of force development, electromyographic (EMG) activity of the biceps and triceps as well as heart rate and blood pressure. The results showed significantly (p < 0.01) higher MVC force (543.6 +/- 29.6 vs. 486.5 +/- 23.0 N), F100 (328.3 +/- 94.5 vs. 274.6 +/- 101.8 N), rate of force development (p = 0.003) (1,851.9 +/- 742.2 vs. 1,591.0 +/- 719.6 N s(-1)) and biceps brachii EMG activity (48%, p < 0.01) in the upright versus inverted condition. There were relatively greater co-contractions with the inverted position (p < 0.01) due to the lack of change in triceps' EMG and the substantial decrease in biceps' EMG. There were no significant changes in trunk EMG activity. With inversion, there were significant decreases in heart rate (16.8%), systolic (11.6%) and diastolic (12.1%) blood pressures (p < 0.0001). These results illustrate decrements in neuromuscular performance with an inverted seated posture which may be related to an altered sympathetic response.
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13
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Cooke WH, Lurie KG, Rohrer MJ, Convertino VA. Human autonomic and cerebrovascular responses to inspiratory impedance. ACTA ACUST UNITED AC 2006; 60:1275-83. [PMID: 16766971 DOI: 10.1097/01.ta.0000221348.82115.a2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND We evaluated the influence of breathing through an inspiratory Impedance Threshold Device (ITD) on autonomic neural and cerebrovascular function. METHODS Eight subjects breathed through a sham ITD (0 cmH2O) and an active ITD (-7 cmH2O) in the supine position. We recorded the ECG, finger photoplethysmographic arterial pressure, cerebral blood flow velocity, and muscle sympathetic nerve activity (MSNA). In a randomized, counterbalanced design, subjects breathed spontaneously and also breathed at a set cadence of 15 breaths/min (0.25 Hz) for 3 minutes each. Data were analyzed in both time and frequency domains. RESULTS Breathing through the active ITD increased mean arterial pressure by approximately 5 mm Hg, heart rate by 2 bpm, and mean cerebral blood flow velocity by 10% (p<0.05) with no effect on MSNA or estimates of vagal-cardiac control (p>0.05). The active ITD did not affect oscillations of interbeat R-R intervals, arterial pressures, or cerebral flow velocities within the low frequency (LF) domain of the power spectrum (p>0.05). Cross spectral analysis revealed no effect of the active ITD on transfer function magnitudes among arterial pressures and R-R intervals, or between arterial pressures and cerebral blood flow velocities at the LF (p>0.05). CONCLUSIONS Our results demonstrate that the ITD increases arterial pressure, heart rate, and cerebral blood flow velocity independent of changes in autonomic cardiovascular control or dynamic cerebral autoregulation. Use of an active ITD in situations of acute central hypovolemia, such as during hemorrhage, may slow the progression to hemodynamic instability in bleeding patients who retain the ability to ventilate spontaneously and robustly.
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Affiliation(s)
- William H Cooke
- Department of Health and Kinesiology, University of Texas at San Antonio (W.H.C.), San Antonio, Texas, and Department of Emergency Medicine, Minneapolis Medical Research Foundation and Hennepin County Medical Center, Minneapolis, Minnesota, USA
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14
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Cooke WH, Salinas J, Convertino VA, Ludwig DA, Hinds D, Duke JH, Moore FA, Holcomb JB. Heart rate variability and its association with mortality in prehospital trauma patients. ACTA ACUST UNITED AC 2006; 60:363-70; discussion 370. [PMID: 16508497 DOI: 10.1097/01.ta.0000196623.48952.0e] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Accurate prehospital triage of trauma patients is difficult, especially in mass casualty situations. Accordingly, the U.S. Military has initiated a program directed toward improving noninvasive prehospital triage algorithms based on available physiologic data. The purpose of this study was to assess heart rate variability and its association with mortality in prehospital trauma patients. METHODS Trauma patients without significant head injury requiring helicopter transport were identified from a retrospective research database. An equal number, unmatched sample of patients who lived were compared with those who died (n = 15 per group). All patients were transported to a single Level I urban trauma center. The primary independent variable was mortality. Patients with Abbreviated Injury Scale head scores >2 were excluded from the analysis, so that the effects seen were based on hemorrhagic shock. Age, sex, Glasgow Coma Scale score (GCS), blood pressure, pulse pressure, pulse, intubation rate, SpO2, mechanism of injury, transport time, and time of death after admission were recorded. R-waves from the first available 120 seconds of usable data were detected from normal electrocardiograms and heart rate variability was assessed. RESULTS Patients who died demonstrated a lower GCS (7.9 +/- 1.4 versus 14.4 +/- 0.2; p = 0.0001) and higher intubation rate (53% of patients who died versus 0% patients who lived). Pulse rate, arterial pressure, and SpO2 were not distinguishable statistically between groups (p = 0.08), but pulse pressure was lower in patients who died (39 +/- 3 versus 50 +/- 2 mm Hg; p = 0.01). Compared with patients who lived, those who died had lower normalized low-frequency (LF) power (42 +/- 6 versus 62 +/- 4 LFnu; p = 0.009), higher high-frequency (HF) power (42 +/- 3 versus 32 +/- 3 HFnu; p = 0.04) and higher HF-to-LF ratio (144 +/- 30 versus 62 +/- 11nu; p = 0.01). With absolute HF/LF adjusted for GCS, the intergroup variance accounted for by HF/LF was reduced to 6% (p = 0.16). CONCLUSIONS Analysis of heart rate variability provides insight into adequacy of autonomic compensation to severe trauma. In our cohort of trauma patients, low pulse pressures coupled with relatively higher parasympathetic than sympathetic modulation characterized and separated patients who died versus patients who survived traumatic injuries when standard physiologic measurements are not different. These data do not suggest advantages of heart rate variability analysis over GCS scores, but suggest future possibilities for remote noninvasive triage of casualties when GCS scores are unattainable.
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Affiliation(s)
- William H Cooke
- Department of Health and Kinesiology, The University of Texas at San Antonio, San Antonio, Texas 78249, USA
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Wilson TD, Cotter LA, Draper JA, Misra SP, Rice CD, Cass SP, Yates BJ. Effects of postural changes and removal of vestibular inputs on blood flow to the head of conscious felines. J Appl Physiol (1985) 2006; 100:1475-82. [PMID: 16439511 DOI: 10.1152/japplphysiol.01585.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prior studies have shown that removal of vestibular inputs produces lability in blood pressure during orthostatic challenges (Holmes MJ, Cotter LA, Arendt HE, Cass SP, and Yates BJ. Brain Res 938: 62-72, 2002; Jian BJ, Cotter LA, Emanuel BA, Cass SP, and Yates BJ. J Appl Physiol 86: 1552-1560, 1999). Furthermore, these studies led to the prediction that the blood pressure instability results in susceptibility for orthostatic intolerance. The present experiments tested this hypothesis by recording common carotid blood flow (CCBF) in conscious cats during head-up tilts of 20, 40, and 60 degrees amplitudes, before and after the surgical elimination of labyrinthine inputs through a bilateral vestibular neurectomy. Before vestibular lesions in most animals, CCBF remained stable during head-up rotations. Unexpectedly, in five of six animals, the vestibular neurectomy resulted in a significant increase in baseline CCBF, particularly when the laboratory was illuminated; on average, basal blood flow measured when the animals were in the prone position was 41 +/- 17 (SE) % higher after the first week after the lesions. As a result, even when posturally related lability in CCBF occurred after removal of vestibular inputs, blood supply to the head was not lower than when labyrinthine inputs were present. These data suggest that vestibular influences on cardiovascular regulation are more complex than previously appreciated, because labyrinthine signals appear to participate in setting basal rates of blood flow to the head in addition to triggering dynamic changes in the circulation to compensate for orthostatic challenges.
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Affiliation(s)
- T D Wilson
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Krishnamurthy S, Wang X, Bhakta D, Bruce E, Evans J, Justice T, Patwardhan A. Dynamic cardiorespiratory interaction during head-up tilt-mediated presyncope. Am J Physiol Heart Circ Physiol 2004; 287:H2510-7. [PMID: 15297255 DOI: 10.1152/ajpheart.00485.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In 28 healthy adults, we compared the dynamic interaction between respiration and cerebral autoregulation in 2 groups of subjects: those who did and did not develop presyncopal symptoms during 70 degrees passive head-up tilt (HUT), i.e., nonpresyncopal (23 subjects) and presyncopal (5 subjects). Airflow, CO2, cerebral blood flow velocity (CBF), ECG, and blood pressure (BP) were recorded. To determine whether influences of mean BP (MBP) and systolic SP (SBP) on CBF were altered in presyncopal subjects, coherencies and transfer functions between these variables and mean and peak CBF (CBFm and CBFp) were estimated. To determine the influence of end-tidal CO2 (ETco2) on CBF, the relative CO2 reactivity (%change in CBFm per mmHg change in ETco2) was calculated. We found that in presyncopal subjects before symptoms during HUT, coherence between SBP and CBFp was higher (P=0.02) and gains of transfer functions between BP (MBP and SBP) and CBFm were larger (MBP, P=0.01; SBP, P=0.01) in the respiratory frequency region. In the last 3 min before presyncope, presyncopals had a reduced relative CO2 reactivity (P=0.005), likely a consequence of the larger decrease in ETco2. We hypothesize that the CO2-mediated increase in resistance attenuates autoregulation such that the relationship between systemic and cerebral hemodynamics is enhanced. Our results suggest that an altered cardiorespiratory interaction involving cerebral hemodynamics may contribute in the cascade of events during tilt that culminate in unexplained syncope.
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Affiliation(s)
- S Krishnamurthy
- No. 2, Wenner-Gren Research Laboratory, Center for Biomedical Engineering, Univ. of Kentucky, Lexington, KY 40506-0070, USA
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Hamner JW, Cohen MA, Mukai S, Lipsitz LA, Taylor JA. Spectral indices of human cerebral blood flow control: responses to augmented blood pressure oscillations. J Physiol 2004; 559:965-73. [PMID: 15254153 PMCID: PMC1665190 DOI: 10.1113/jphysiol.2004.066969] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We set out to fully examine the frequency domain relationship between arterial pressure and cerebral blood flow. Oscillatory lower body negative pressure (OLBNP) was used to create consistent blood pressure oscillations of varying frequency and amplitude to rigorously test for a frequency- and/or amplitude-dependent relationship between arterial pressure and cerebral flow. We also examined the predictions from OLBNP data for the cerebral flow response to the stepwise drop in pressure subsequent to deflation of ischaemic thigh cuffs. We measured spectral powers, cross-spectral coherence, and transfer function gains and phases in arterial pressure and cerebral flow during three amplitudes (0, 20, and 40 mmHg) and three frequencies (0.10, 0.05, and 0.03 Hz) of OLBNP in nine healthy young volunteers. Pressure fluctuations were directly related to OLBNP amplitude and inversely to OLBNP frequency. Although cerebral flow oscillations were increased, they did not demonstrate the same frequency dependence seen in pressure oscillations. The overall pattern of the pressure-flow relation was of decreasing coherence and gain and increasing phase with decreasing frequency, characteristic of a high-pass filter. Coherence between pressure and flow was increased at all frequencies by OLBNP, but was still significantly lower at frequencies below 0.07 Hz despite the augmented pressure input. In addition, predictions of thigh cuff data from spectral estimates were extremely inconsistent and highly variable, suggesting that cerebral autoregulation is a frequency-dependent mechanism that may not be fully characterized by linear methods.
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Affiliation(s)
- J W Hamner
- Laboratory for Cardiovascular Research, Research and Training Institute, Hebrew Rehabilitation Center for Aged, Boston, MA 02131, USA
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