The Impact of OSA on Exercise: A Window Into Chronic Disease Risk Trent A. Hargens, PhD Department...
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Transcript of The Impact of OSA on Exercise: A Window Into Chronic Disease Risk Trent A. Hargens, PhD Department...
The Impact of OSA on Exercise: A Window Into
Chronic Disease RiskTrent A. Hargens, PhD
Department of KinesiologyJames Madison University
Outline• Background on OSA-chronic disease
• Physiological mechanisms of disease link
• Exercise Testing as a diagnostic/prognostic tool
• Variables of interest
• Exercise responses in OSA patients
• Summary
OSA
Disease Mechanisms
Associated CV Disease
HypoxemiaReoxygenationHypercapnia
Intrathoracic PressureArousals
Sleep Deprivation
Sympathetic activationMetabolic dysregulationLeft atrial enlargement
Endothelial dysfunctionSystemic inflammation
Hypercoagulability
HypertensionHeart FailureArrhythmias
Renal diseaseStroke
Myocardial infarction
Sudden cardiac death
Systemic
Pulmonary
Somers et al., Circulation 2008;118:1080-1111.
OSA and Insulin Resistance
Homeostasis model assessment index
Independent of age, gender, ethnicity, smoking status, BMI, waist circumference, and sleep duration
Punjabi et al., Am J Epidemiol 2004;160:521-530
OSA and Heart Failure• Prevalence of OSA in CHF population
estimated to be as high as 40% • Javaheri, Circulation 1998;97:2154–2159
Mansfield et al., Am J Respir Crit Care Med 2004;169:361-366
Significantly improved LV function in CHF patients with OSA following CPAP treatment
OSA and Heart Failure
LVEDD (mm) LVESD (mm) EF (%)
LVEDV (ml) LVESV (ml)
**
*
*
*
Kourouklis SP, et al, Int J Cardiol (2012), http://dx.doi.org/10.1016/j.ijcard.2012.09.101. Article in press
OSA and Hypertension
ADJUSTED FOR BMI, NECK, WHR, ALCOHOL USE, SMOKING
P for trend = 0.005
Nieto et al., Jama 2000;283:1829-1836.
OSA and HypertensionP for trend < 0.001
ADJUSTED FOR BASE-LINE HYPERTENSION STATUS, NON-MODIFIABLE RISK FACTORS, HABITUS, AND WEEKLY ALCOHOL AND CIGARETTE USE
Peppard et al., N Engl J Med 2000;342:1378-1384.
OSA and Cardiovascular Disease
Diagnostic Group
Adjusted OR (95% CI)
P
Snoring 1.03 (0.31-1.84) 0.88
Untreated mild OSA
1.15 (0.34-2.69) 0.71
Untreated severe OSA
2.87 (1.17-7.51)0.025
*
CPAP 1.05 (0.39-2.21) 0.74
Odds ratio for cardiovascular death
Marin et al., Lancet 2005;365:1046-1053.
OSA and Cardiovascular Disease
Diagnostic Group
Adjusted OR (95% CI)
P
Snoring 1.32 (0.64-3.01) 0.38*
Untreated mild OSA
1.57 (0.62-3.16) 0.22*
Untreated severe OSA
3.17 (1.12-7.52)0.001
*
CPAP 1.42 (0.52-3.40) 0.29*
Odds ratio for non-fatal cardiovascular events
Marin et al., Lancet 2005;365:1046-1053.
OSA and Cardiovascular DiseaseKaplan-Meier curvesA. FatalB. Non-Fatal
Authors conclude that OSA independently increases risk for CV events
Marin et al., Lancet 2005;365:1046-1053.
OSA and Cardiovascular DiseaseWisconsin Sleep Cohort
“Mortality follow-up of the Wisconsin Sleep Cohort, comprising 20,963 person-years, indicates that severe SDB is significantly associated with a 3-fold increased all-cause mortality risk (P < 0.0008), independently of age, sex, BMI, and other potential confounders
OSA Disease Mechanisms
OSA HTNSympathetic Activation
Hyperleptinemia
Baroreflex Sensitivity
Chemoreflex Activation
Insulin Resistance
RAAS Activity
Oxidative StressEndothelial Dysfunction
Systemic Inflammation
Adapted from Wolk et al., Clinics in chest medicine 2003;24:195-205.
Sympathetic Activation in OSA
Heightened SNA persists during waking hours, not just during sleep.
Improvements in SNA during sleep were seen in this group with CPAP
Somers VK et al. Sympathetic neural mechanisms in obstructive sleep apnea. J Clin Invest 1995;96:1897-1904.
Sympathetic Activation in OSA
SNA was:1. Greater in Obese vs. lean2. Greater in Obese + OSA vs Lean + OSA3. Greater in OSA vs. without OSA (regardless of wt)
Therefore:1. Sympathetic activation seen in obesity is independent of OSA2. OSA’s impact on SNA is independent of body weight, but ADDITIVE
Grassi et al., Hypertension 2005;46:321-325.
Exercise Question• If OSA impacts so many physiological systems,
how may those adaptations manifest during acute exercise?
• Does it negatively impact their ability to exercise, ability to improve health/fitness, etc?
• Could changes with exercise provide prognostic or diagnostic clues as OSA risk?
• Given that SO MANY OSA sufferers go undiagnosed
• 93 and 82% of females and males, who would benefit from treatment, remain undiagnosed (Young et al., 1997)
Circulation. 2010;122:191-225
“Cardiopulmonary exercise testing (CPX) offers the clinician the ability to obtain a wealth of information beyond standard exercise electrocardiography testing that when appropriately applied and interpreted can assist in the management of complex cardiovascular and pulmonary disease.”
• “the addition of ventilatory gas exchange measurements during exercise testing provides a wide array of unique and clinically useful incremental information that heretofore has been poorly understood and underutilized by the practicing clinician. The reasons for this are many...”
Gas Exchange Variables of Interest
• Peak rate of oxygen uptake (VO2peak)
• Reflects the capacity of the heart, lungs, and blood to deliver O2 to the muscles. Criterion measure of Aerobic Fitness.
• VO2max = (HR x SV) x [C(a-v)O2]
• Minute ventilation (VE)
• Amount of air moved in and out of the lungs (Liters/min)
• Ventilatory Equivalent for oxygen consumption (VE/VO2)
• Volume of air you must move to consume 1 Liter of O2.
• Marker of ventilatory efficiency
Gas Exchange Variables of Interest
• Ventilatory Equivalent for CO2 (VE/VCO2)
• Volume of air that you must move to blow off 1 Liter of CO2.
• Marker of ventilatory efficiency for CO2 clearance
• VE/VCO2 Slope
• Powerful marker of ventilatory efficiency
• Slope of relationship from onset of exercise to peak
• MOST research done in area of heart failure
Peak VO2 responses in OSA
Reduced VO2peak
Lin et al., 2006
Grote et al., 2004
Tremel et al., 1999
Schonhofer et al., 1997
Vanuxem et al., 1997
No Change in VO2peak
Kline et al., 2012
Maeder et al., 2008
Hargens et al., 2008
Kaleth et al., 2007
Alonso-Fernandez et al., 2006
Ozturk et al., 2005
Peak VO2 vs. VE/VCO2 Slope in CHF
Peak VO2 (ml.kg-1.min-1)P1 < 13.0P2 13-16.5P3 16.6-21.6P4 > 21.6
VE/VCO2 SlopeV1 < 27.7V2 27.7-34.5V3 34.6-42.1V4 > 42.1 Francis et al., Eur Heart J 2000
Peak VO2 vs. VE/VCO2 Slope in CHF
Arena et al., Circulation. 2007;115:2410-2417
slope > 30 now considered “abnormal”
Pathophysiological mechanisms of an elevated VE/VCO2 slope
CentralDecreased right sided cardiac output
Increased pressure in pulmonary vasculaturesecondary to increased left sided pressure
Compromised pulmonary vessel dilationsecondary to decreased NO production
HighVE/VCO2 slope
Central
Abnormal chemoreceptorreflex
Peripheral
Abnormal chemoreceptor
and ergoreceptor reflex
Increased ventilation-perfusion mismatching
HeightenedVE
response toexercise
VE/VCO2 slope in CSA (with CHF)
VO2peak did not differ between groups
Artz et al., Circulation. 2003;107:1998-2003
Hargens et al., 2009
Altered ventilatory responses to exercise testing in young adult men with obstructive sleep apnea. Respir Med 2009;103:1063-9.
Hargens et al., 2009
VE/VCO2 slope - AHI correlation: r = 0.56, P = 0.001
To date, no other studies have examined this explicitly in OSA
“During dynamic exercise, heart rate increases linearly with work rate and VO2, but the slope and magnitude of heart rate acceleration are influenced by age, deconditioning, body position, type of exercise, and various states of health and therapy, including heart transplant. Chronotropic incompetence, defined as either failure to achieve 85% of the age-predicted maximal heart rate or a low chronotropic index (heart rate adjusted to the MET level), is associated with increased mortality risk in patients with known cardiovascular disease.”
Balady et al
Group Age AHI VO2peak HRpeak
OSA 45.6 24.7* 21.9 152.3
Control 40.2 2.5 21.9 168.4
Sleep Med 2007;8:160-168.
Kaleth et al., 2007
“The repetitive blood pressure surges during sleep and increased sympathetic activity during wakefulness may result in the structural downregulation of cardiac Beta-adrenergic receptors and/or alter the baroreflex set point to a higher level of pressure.”
N Engl J Med 1999;341:1351-1357.
Subjects were without a history of heart failure or coronary revascularization and without pacemakers.
6 year follow-up in 2428 subjects
Balady
Attenuated HR Recovery
• Also a reflection of autonomic dysfunction
• Imbalance between sympathetic and parasympathetic activation
Hargens et al., 2008
Sleep 2008;31:104-110.
“Attenuation of the HR recovery response in OSA may reflect predominance and/or slower withdrawal of sympathetic influence; how this pattern may be affected by parasympathetic reactivation that normally slows HR is uncertain.”
Maeder et al., 2008
Maeder MT, Munzer T, Rickli H, Schoch OD, Korte W, Hurny C, Ammann P. Association between heart rate recovery and severity of obstructive sleep apnea syndrome. Sleep Med 2008;9:753-761.
Maeder et al., 2009
• 40 subjects with OSA (AHI = 37)
• ~ 8 months of CPAP treatment
• Exercise test responses compared pre/post
*
Maeder MT, et al. Continuous positive airway pressure improves exercise capacity and heart rate recovery in obstructive sleep apnea. Int J Cardiol 2009;132:75-83.
Heart Rate Variability
HRV is the variation of beat to beat intervals among successive heart rate
cycles.
Heart Rate Variability• Heart rate variability (HRV) serves as a reflection of the balance
between the sympathetic and parasympathetic nervous system
• Frequency-domain analysis of HRV have been established as a simple and non-invasive marker
• LF = low frequency (0.04-0.15 Hz). Reflection of sympathetic/parasympathetic balance
• HF = high frequency (0.15-0.40 Hz). Reflection of parasympathetic activity
• LF/HF = ratio. Reflection of sympathetic/parasympathetic balance
• OSA patients have demonstrated autonomic dysfunction, reflected in diminished vagal activity and heightened sympathetic activity, measured through HRV. This is seen even during normal waking hours. (At rest)
• Aydin, Tex Heart Inst J 2004;31:132-6
Hargens et al., 2012• 9 High risk OSA, 16 Controls
• Max cycle exercise tests
• HRV assessed throughout exercise and recovery
* *
At peak exercise
Findings suggest that heightened sympathetic activation (LF) and reduced parasympathetic activation (HF) may manifest during high intensity exercise. Further examination is warranted.
Heart Rate Variability is Reduced at Peak Exercise in Individuals at Risk for Sleep Apnea. Medicine & Science in Sports & Exercise 2012;44:S163.
Hargens et al., 2013
• Purpose: To examine whether measures obtained during exercise testing may aid in clinical risk stratification for OSA
• 102 overweight subjects
• Cycle max exercise test
• Screened for possible OSA with Embletta
• Logistic regression analysis with AHI > 15 criteria for OSA
In press: Medicine & Science in Sports and Exercise
Hargens et al., 2013
• Significant univariate correlations to AHI
• Age
• BMI
• Total Cholesterol
• Triglycerides
• Peak HR
• VO2peak
• HRdiff (minutes 1 - 5 of recovery)
EpworthBP were not
Hargens et al., 2013• Logistic Regression revealed that HRdiff5 was
the ONLY significant independent predictor of OSA
• Beta = -0.215, P = 0.009
• R2 for model = 0.57, P < 0.001
• HRdiff3: P = 0.053
• Univariate ROC analysis
• AUC for HRdiff5 = 0.73, P = 0.002
• AUC for BMI = 0.77, P < 0.001
Current Study• The impact of untreated OSA on Cardiac
Rehabilitation Participation
• Research question: Does untreated OSA negatively impact the progress of patients undergoing cardiac rehabilitation?
• Non-invasive impedance cardiography measures
• Cardiac output, stroke volume, ejection fraction, systemic vascular resistance
• Study in conjunction with Radford University, Carillion Roanoke Community Hospital, Rockingham Memorial Hospital
Current Study
• Currently have recruited and screened 48 subjects
• Screened for OSA with ApneaLink device and read by sleep technician
• 38 subjects have AHI > 5
• Most did not know before screening. Small number (< 5) may have known of OSA presence/possibility
• 10 subjects have AHI < 5
Acknowledgements• William Herbert, PhD
• Stephen Guill, PhD
• Adrian Aron, PhD
• Shelly Nickols-Richardson, PhD, RD
• Donald Zedalis, MD
• William Cale, MD
• Katrina Butner, PhD, RD
• Laura Newsome, PhD
• Tom Rice, MS
• Amanda Mallory, MS
• Steve Vesbach, MS
• Erin Ledden, MS
• Cassandra Ledman, MS
• Brooke Shafer, BS