Obstructive Sleep Apnea and Hypertension

1. Obstructive Sleep
Apnea and
Hypertension
Christine Won, M.D.
Stanford Sleep Disorders Center

2. Objectives
 Hypertension
 Definition
 Risk Factors
 Significance
 Causes
 Treatment
 Obstructive Sleep Apnea
 Association with Hypertension
 Physiology
 Causes
 Treatment
 Other Cardiovascular Diseases

3. Definition of Hypertension
 Normal blood pressure: systolic
<120 mmHg and diastolic <80
 Pre-hypertension: systolic 120-139
or diastolic 80-89
 Hypertension:
Stage 1: systolic 140-159 or diastolic
90-99
Stage 2: systolic 160 or diastolic 100

4. Hajjar, I, Kotchen, TA. JAMA 2003; 290:199.
Prevalence of Hypertension

5. Mancia, G, Parati, G, Pomidossi, G, et al, Hypertension 1987; 9:209
White-Coat Hypertension

6. Risk Factors for Hypertension
 More common and more severe in blacks
 It is likely that increased salt intake is a
necessary but not sufficient cause for
hypertension
 Excess alcohol intake increases risk
 High cholesterol may also associated with the
development of hypertension
 Hypertension may be more common among
those with certain personality traits, such as
hostile attitudes and time urgency/impatience

7. Stevens, VJ, Corrigan, SA, Obarzanek, E, et al, Arch Intern Med 1993; 153:849
Obesity and Hypertension
 Obesity is associated with an increased risk of
hypertension, and weight gain appears to be a
main determinant of the rise in blood pressure
that is commonly seen with aging
 Weight loss improves blood pressure

8. Why is Hypertension Important?
 Hypertension is associated with a number of
serious adverse effects
 The likelihood of developing these complications
varies with the blood pressure
 The increase in risk begins as the blood
pressure rises above 110/75 mmHg and, at any
blood pressure, is importantly affected by the
presence or absence of other risk factors

9. Why is Hypertension Important?
 Premature cardiovascular disease
 Coronary heart disease
 Heart failure
 Stroke
 Intracerebral hemorrhage
 Chronic renal insufficiency and end-stage renal
disease
 Acute, life-threatening emergency

10. What Causes Hypertension?
 Increased sympathetic neural activity
 Increased angiotensin II activity and mineralocorticoid
excess
 Reduced adult nephron mass
 may be related to genetic factors, intrauterine disturbance (eg,
hypoxia, drugs, nutritional deficiency), and post-natal
environment (eg, malnutrition, infections)
 Hypertension is twice as common in those who have
hypertensive parents; genetic factors account for
approximately 30% of the variation in blood pressure

11. Benefit of Treating Hypertension
 Antihypertensive therapy has been associated
with 40 percent reduction in stroke; 25 percent in
myocardial infarction; and more than 50 percent
in heart failure
 It is estimated that control of hypertension to
below 140/90 mmHg could, in men and women,
prevent 19 and 31 percent of coronary heart
disease events

12. Modification Recommendation Approximate SBP
reduction
Weight
reduction
Maintain normal body weight (BMI 18.5 to
24.9 kg/m2)
5-20 mmHg per
10-kg weight loss
Adopt DASH
eating plan
Consume a diet rich in fruits, vegetables, and
low-fat dairy products with a reduced content
of saturated and total fat
8 to 14 mmHg
Dietary sodium
reduction
Reduce dietary sodium intake to no more than
100 meq/day (2.4 g sodium or 6 g sodium
chloride)
2 to 8 mmHg
Physical activity Engage in regular aerobic physical activity
such as brisk walking (at least 30 minutes per
day, most days of the week)
4 to 9 mmHg
Moderation of
alcohol
consumption
Limit consumption to no more than 2 drinks
per day in most men and no more than 1 drink
per day in women and lighter-weight persons
2 to 4 mmHg
The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood
Pressure, JAMA 2003; 289:2560
Lifestyle modifications in the management of hypertension

13. Obstructive Sleep Apnea and
Hypertension
 Wisconsin Sleep Cohort Study
 Dose-dependent relationship between severity of sleep apnea and risk
of developing hypertension
 Odds for developing hypertension during a 4-8 year follow-up period
compared to subjects with no apneas or hypopneas was 2.0 if AHI was
5-15, and 3.0 if AHI>15
 The Sleep Heart Health Study
 A cross-sectional analysis of a large community-based multi-center
population showed an increase in odds of 1.4 for hypertension when
AHI > 30 compared to those with AHI < 1.5
 The Nurses’ Health Study
 Increase in risk of 1.6 for the development of hypertension over an 8-
year follow-up period in regular snorers compared to non-snorers

14. The Relationship between Obstructive
Sleep Apnea and Hypertension
 The odds of having
hypertension is 37%
greater in persons with
obstructive sleep apnea
 The odds of having
hypertension is 46%
greater in those who
spend greater percentage
of sleep time below 90%
oxygen saturation
Nieto, F. J. et al. JAMA 2000;283:1829-1836

15. Peppard et al. NEJM. 2000; 342:1378-1384
The Relationship between Obstructive
Sleep Apnea and Hypertension
 Compared to those
with AHI=0, the odds of
having hypertension
was 42% greater if AHI
was 0.1-5, 2x greater if
AHI was 5-15, and
almost 3x greater if
AHI was more than 15
per hour

16. Obstructive Sleep Apnea: Physiology

17. Obstructive Sleep Apnea: Physiology
www.qeok.com/lung-cancer/asbestosis-picture.jpg

18. Obstructive Sleep Apnea and
Cardiovascular Effects
Obstructive Apnea
• Negative Intrathoracic
Pressure (Mueller
Maneuver)
• Hypoxia
• Hypercapnia
Resumption of
breathing
• Labile blood
pressure
EEG arousals
• Fragmented sleep
• Increased sympathetic activity

19. Tilkian AG, Guilleminault C. Ann Intern Med. 1976 Dec;85(6):714-9
Overnight Polysomnogram in a Patient with Obstructive Sleep Apnea
EEG
EOG
EKG
SBP
PAP
SAO2
RESP

20. The Sympathetic System
 Many early studies demonstrated abnormal
autonomic activity in both animal models and in
humans with obstructive sleep apnea:
 Increased norepinephrine levels
 Increased muscle sympathetic nerve activity

21. Narkiewicz et al. Circulation 1999;100:2332-2335
Sympathetic System: Muscle Nerve
Activity
 Compared muscle
sympathetic nervous activity
(MSNA) of blood vessels in
untreated and treated OSA
at baseline and after 1, 6, 12
months of CPAP
 MSNA was similar during
repeated measurements in
the untreated group
 In contrast, MSNA
decreased significantly over
time in patients treated with
CPAP

22. Sympathetic System: Norepinephrine
Dimsdale et al, Sleep 1995;18:377-81
 24-hr urinary NE
increased 45% in apneic
(RDI>20) compared to
non-apneic patients.
 CPAP treatment lowered
daytime plasma NE
levels by 23%; Placebo
had no effect on NE
levels

23. Treating Obstructive Sleep Apnea
 Several trials have demonstrated improved
systolic and diastolic blood pressures with both
short-term and long-term CPAP use
 Regular CPAP use has also shown to improve
blood pressure in patients with refractory
hypertension who were requiring three or more
antihypertensive medications

24.  The seventh Joint National Committee on
Prevention, Detection, Evaluation, and
Treatment of High Blood Pressure
recommends evaluating for and treating
obstructive sleep apnea in adults with
hypertension

25. Obstructive Sleep Apnea and other
Cardiovascular Diseases
www.rjmatthewsmd.com/Definitions/img/osa-fig3.gif

26. Summary
 Hypertension is a serious disease that affects many
people
 Scientific evidence for a link between obstructive sleep
apnea and hypertension is compelling
 Sleep apnea is thought to contribute to hypertension by
increasing sympathetic nervous system activity and
causing vascular dysfunction
 Animal studies have demonstrated that sleep apnea can
cause hypertension
 Human epidemiological studies confirm that untreated
sleep apnea increases the risk of having hypertension

27. Summary
 CPAP stabilizes the upper airway, preventing collapse
and the acute cardiovascular and hemodynamic
consequences of obstructive sleep apnea
 CPAP applied over several weeks reduces both systolic
and diastolic blood pressure by ~10 mm Hg. These
reductions are predicted to reduce stroke risk by 56%
and coronary heart disease event risk by 37%
 The United States National Heart, Lung, and Blood
Institute now recognizes sleep apnea as a significant and
reversible cause of hypertension

28. Thank You