Efficacy of CPAP on the airways

1. Efficacy of Continuous Positive Airway
Pressure in Cardiovascular
Complications
of Obstructive Sleep Apnea
Presenter : Syed M.Umair

2. Introduction
• In today's Lecture, we’ll learn how Continuous Positive Airway
Pressure (CPAP) impacts cardiovascular health in obstructive sleep
apnea (OSA).
• Importance: Establishing the link between OSA and cardiovascular
complications is crucial for comprehensive patient care.

3. Cardiovascular Complications in OSA
Heart Challenges in OSA
• OSA Severity: The severity of OSA directly correlates with increased
risks of cardiovascular complications.
• Types: OSA is associated with
• Systemic hypertension
• Heart failure
• Arrhythmias
• Myocardial infarction
• Pulmonary hypertension.

4. Pathophysiology of Cardiovascular
Complications
Mechanisms of Disruption
• Intermittent Hypoxia: The recurring pattern of oxygen depletion and
restoration is a key contributor to cardiovascular pathophysiology in
OSA.
• Autonomic Nervous System: Hypoxia triggers sympathetic over-
activation, leading to disrupted autonomic responses during sleep.

5. Hypoxia and Sympathetic Over Activation:
• During episodes of obstructive sleep apnea (OSA), the upper airway
becomes partially or completely blocked, leading to interruptions in
breathing and decreased oxygen levels in the blood.
• Hypoxia, or inadequate oxygenation, is a hallmark feature of OSA. In
response to hypoxia, the body activates the sympathetic nervous
system as part of its natural defense mechanisms.
• This sympathetic over-activation increases heart rate, constricts blood
vessels, and releases stress hormones like adrenaline, preparing the
body to respond to the perceived threat of oxygen deprivation.

6. Systemic Hypertension
Independent Risk
• OSA Contribution: OSA is identified as an independent and significant
risk factor for hypertension.
• AHI Relationship: The risk of hypertension doubles with an Apnea-
Hypopnea Index (AHI) of 5–15/h and triples with an AHI above 15/h.

7. The apnea-hypopnea index (AHI)
• The apnea-hypopnea index (AHI) is typically measured during a sleep study,
also known as polysomnography.
• During a sleep study, various physiological parameters are monitored while a
person sleeps, including airflow, respiratory effort, oxygen levels, and brain
activity.
• The AHI is calculated by dividing the total number of apneas and hypopneas
recorded during the sleep study by the total sleep time in hours.
• It’s expressed as the number of apneas and hypopneas per hour of sleep.AHI
values can help classify the severity of obstructive sleep apnea
• Normal: AHI < 5 events per hour
• Mild: AHI between 5 and 15 events per hour
• Moderate: AHI between 15 and 30 events per hour
• Severe: AHI > 30 events per hour

8. CPAP Therapy Effects on Hypertension
Clinical Impact
• Blood Pressure Reduction: Evidence from controlled trials indicates an
average drop of approximately 10 mmHg in blood pressure with CPAP
in moderate-to-severe sleep apnea.
• Patient Variation: The impact is less pronounced in patients with mild
OSA or those who are normotensive.

9. Coronary Artery Disease (CAD)
Morning Risks
• Increased Morning Risks: OSA patients face elevated risks of Acute
Coronary Syndrome (ACS) and sudden cardiac death during the early
morning hours.
• Research suggests that there is a higher incidence of cardiovascular events,
such as heart attacks and strokes, during the early morning hours.
• This is partially due to the natural circadian rhythm of the body, where
blood pressure, heart rate, and the likelihood of blood clot formation are
elevated upon waking.
• Effective management of OSA can help stabilize blood oxygen levels,
reduce cardiovascular stress, and mitigate the risk of morning-related
cardiovascular events.

10. CPAP Therapy Effects on CAD
Early Intervention
• Improved Indicators: CPAP has shown efficacy in reducing angina and
nocturnal myocardial ischemia.
• Vascular Health: Studies reveal positive changes in pulse wave
velocity, carotid intima wall thickness, and carotid artery diameter.

11. Heart Failure
Intricate Connection
• High Prevalence: OSA is prevalent among heart failure patients (11–
38%), and even those with mild heart failure exhibit increased OSA
prevalence (15%).
• Different Phenotype: OSA patients with heart failure are typically
overweight habitual snorers, distinct from heart failure patients with
central sleep apnea.

12. CPAP Therapy Effects on Heart Failure
Systolic and Diastolic Benefits
• Positive Impact: CPAP has demonstrated improvements in both
systolic and diastolic functions in patients with heart failure.
• In patients with obstructive sleep apnea (OSA), CPAP therapy
prevents episodes of apnea and hypopnea, which can cause oxygen
desaturation and increase sympathetic nervous system activity, both of
which contribute to increased cardiac workload.
• By ensuring continuous airflow and stable oxygen levels during sleep,
CPAP therapy reduces the strain on the heart, leading to improvements
in systolic function over time.

13. Pulmonary Arterial Hypertension (PAH)
Mild PAH Occurrence
• PAH Prevalence: Studies report a prevalence of 17–43% for mild PAH
in patients with OSA, with associated factors including high AHI, low
Pao2, high Paco2, low FEV1, and increased BMI.
• Clinical Significance: The clinical significance of mild OSA-related
PAH is yet to be fully understood.

14. CPAP Therapy Effects on PAH
Reducing Pulmonary Pressure
• CPAP's Role: Studies indicate a reduction in pulmonary artery
pressure after 3–6 months of CPAP therapy, with likely positive effects
in severe OSA, OSA-induced PAH, and adherent users.
• In conditions such as OSA and OSA-induced PAH, there can be
increased pulmonary artery pressure due to factors like intermittent
hypoxia, increased sympathetic nervous system activity, and
inflammation.
• CPAP therapy addresses these underlying mechanisms by providing
continuous positive airway pressure, which prevents airway collapse
and maintains adequate oxygenation during sleep

15. Stroke
Association Strength
• Robust Association: the robust association between OSA and stroke underscores
the importance of identifying and treating OSA as part of stroke prevention efforts.
• OSA contributes to stroke risk through various biological mechanisms. During
episodes of apnea and hypopnea, there are fluctuations in blood oxygen levels and
increased sympathetic nervous system activity, leading to systemic inflammation,
endothelial dysfunction, and oxidative stress.
• These physiological changes promote the development of atherosclerosis,
hypertension, and other cardiovascular risk factors, which are primary contributors
to stroke risk.
• Severity Impact: The risk of stroke and death increases with the severity of OSA,
with an over threefold increase in risk for those with an AHI above 36.

16. CPAP Therapy Effects on Stroke
Addressing CPAP Tolerance
• Variable Tolerance: Studies report results on CPAP acceptance in
stroke patients, indicating a need for individualized approaches.
• Indirect Risk Reduction: CPAP's potential to reduce blood pressure,
sympathetic nerve activity, and arterial stiffness contributes to a
lowered risk of stroke in OSA patients.

17. Conclusion
Comprehensive Impact
• OSA's Significance: OSA significantly impacts cardiovascular health,
emphasizing the need for a holistic approach to patient care.
• CPAP's Promise: Continuous Positive Airway Pressure emerges as a
promising intervention, stressing the importance of patient adherence.
• Future Research: Encouragement for ongoing studies to refine and
expand CPAP applications, ensuring optimized outcomes for patients.