Have you ever had trouble getting up in the morning or felt excessive midday fatigue following a “good” night’s sleep? If so, you might want to pay attention to this case scenario.
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OSAS case scenario
Mr. Kareem, a 52-year-old office clerk, arrived with his wife to visit the doctor. His chief complaint was shortness of breath. He further complained that his breathing becomes more laborious when walking up a flight of stairs. There has been no coughing, sputum production, or other signs of respiratory distress. He stated that he had gained almost 5 kgs in the past six months.
His past medical history (PMH) revealed that he suffers from chronic hypertension, type 2 diabetes, hyperlipidemia, and a history of childhood asthma with no exacerbations in adulthood. His social history indicates that he is an ex-smoker who quit smoking eight years ago after a 5-pack-year smoking history and has never consumed alcoholic beverages. He is married and has three children.
His wife, who is quite concerned about her husband, stated that he has been wearier lately when he gets home from work and has difficulty concentrating on household tasks. She also claimed that he frequently falls asleep while watching television. Additionally, he has been restless at night, with loud snoring. He also has trouble waking up in the morning and feels sleepy during the day. In the morning, he has two cups of coffee and consumes numerous caffeinated sodas throughout the day.
On physical examination, his blood pressure was 145/70 mmHg, oxygen saturation of 94% on room air, Body mass index (BMI) of 37 kg/m2, high arched palate, Friedman tongue position III, and neck size of 45 cm. Respiratory, cardiac, and abdominal examinations are unremarkable.
His Epworth sleepiness score (ESS) is 13 out of 24, and following a series of investigations, Mr. Kareem was diagnosed with obstructive sleep apnea syndrome (OSAS).
What is sleep apnea?
During sleep, apnea is defined as a cessation of airway flow for 10 seconds or longer, while hypopnea is a cessation of 50% of airway flow for 10 seconds or longer.
Sleep apnea (SA) is a potentially fatal sleep disorder marked by 30 or more recurring episodes of apnea and hypopnea during seven hours of sleep. Sleep apnea is further categorized as obstructive sleep apnea (OSA) if accompanied by persistent respiratory effort, central sleep apnea (CSA) in the absence of respiratory effort, and complex sleep apnea (mixed sleep apnea), if the respiratory effort is persistent or absent periodically.
Obstructive sleep apnea (OSA) is a form of sleep-disordered breathing that is characterized by upper airway collapse resulting in obstructive apneas and hypopneas with desaturation. OSA associated with excessive daytime sleepiness is commonly called obstructive sleep apnea syndrome (OSAS). In contrast, sleep apnea induced by a disturbance in respiratory regulation caused by neurological illnesses is known as central sleep apnea. When opposed to obstructive sleep apnea, this condition is relatively less common.
How common is OSAS and Risk factors?
OSA affects nearly three to five per cent of the population. It is particularly prevalent in overweight, middle-aged males.
Multiple risk factors are involved with OSAS. These are,
• Male gender
• Old age (>60 years)
• Menopause
• Obesity (BMI >30)
• Endocrine diseases including acromegaly and hypothyroidism
• Craniofacial and upper airway abnormalities, such as deviated nasal septum, nasal polyps, turbinate hypertrophy, etc.
• Enlarged tonsils or trisomy 21 in children.
• Alcohol use
• Sedatives and strong analgesics
What is the disease mechanism?
Sleep apnea is caused by the pharynx repeatedly occluding during sleep, usually at the level of the soft palate. During inspiration, a negative pressure is created within the pharynx. Thus, the pharynx is sucked close. When awake, Upper airway dilating muscles, such as the palatoglossus and genioglossus, contract actively during inspiration to maintain airway patency, but during sleep, these muscles become hypotonic, making it difficult for these muscles to maintain pharyngeal patency.
A combination of an anatomically narrow palatopharynx and under-activity of the airway dilating muscles during sleep causes inspiratory airway blockage in a small percentage of patients. This incomplete blockage and critical narrowing of the upper airway causes snoring and hypopneas, respectively.
As obstructive apnea gradually becomes more severe, it causes hypoxia and higher inspiratory effort and wakes the patient briefly, allowing the dilating muscles to reopen the airway. Patients have no remembrance of these awakenings since they are so transient. This apnea and awakening cycle can occur numerous times per night, resulting in severe sleep deprivation and subsequent blood pressure changes, leading to cardiovascular disorders over time.
What are the possible complaints?
Now let’s dive into our case scenario. We observed that Mr. Kareem experienced excessive daytime sleepiness, restless sleep, loud snoring, unrefreshed sleep, and impaired cognitive function. Out of these, excessive daytime sleepiness and loud snoring are the most common symptoms of obstructive sleep apnea.
In addition, there can be abrupt awakenings accompanied by gasping or choking (nocturnal choking), morning headache, and reduced libido. In a minority of patients, morning drunkenness, ankle swelling, nocturia, and mood changes, such as depression and irritability, are also observed.
What if this isn’t OSAS?
Persistent sleepiness doesn’t always mean that you suffer from obstructive sleep apnea. There are a plethora of differential diagnoses for chronic daytime sleepiness, including central sleep apnea, Pickwickian syndrome, periodic limb movement disorder, narcolepsy, drug use, neurological lesions, idiopathic hypersomnolence, and depression. A careful history and investigations can exclude all these conditions.
As we discussed above, central sleep apnea is very similar to obstructive sleep apnea, except the original cause of apnea. During a physical examination, the BMI and the presence or absence of any anatomical abnormalities in the respiratory passage can be used to distinguish between these two conditions.
Pickwickian syndrome is characterized by the triad of obesity, sleep apnea, and chronic hypercapnia while awake when no other known causes of hypercapnia are present.
Sleep disturbances brought on by kicking motions, uremia, and related neuropathies are common symptoms of periodic limb movement disorder. In contrast, narcolepsy is associated with the symptoms of cataplexy, hallucinations, excessive daytime sleepiness, sleep paralysis, and sleep disruption.
The patient’s drug history can exclude sleep apnea due to drug use. Neurological lesions can be easily excluded by additional investigations such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT), or electroencephalogram (EEG). Idiopathic hypersomnolence is characterized by lengthy nighttime sleep and long naps, in addition to difficulty waking from sleep. And finally, a simple mental health checkup can help rule out depression.
What to look for in the physical examination?
A thorough physical examination is an indispensable part of the diagnostic process. We should identify the risk factors of OSA in the patient and the complications, if any.
The BMI should be noted if it’s greater than 30 kg/m2 and considered obese, which is a major risk factor for OSA. The neck circumference is measured and evaluated whether it’s greater than 17 inches in males and 15 inches in females.
Tongue position should be assessed to check whether the Friedman tongue position is class 3 or greater or, in terms of Mallampati score, class 3 or higher.
Evaluate for nasal abnormalities, such as turbinate hypertrophy, deviated septum, etc. Also, look for the mouth and oral cavity features such as retrognathia, micrognathia, macroglossia, jaw misalignment, high-arched palate, and enlarged tonsils.
The organ system examination is typically normal in patients with OSA, in the absence of complications, such as hypertension, metabolic syndrome, or stroke.
How to arrive at a diagnosis?
In Mr. Kareem’s case, we can arrive at an initial diagnosis of OSAS merely with his case history, symptoms, and his sleeping patterns provided by his wife. But in most cases, an initial diagnosis is not enough to start with the treatment, and several tests should be done to confirm the diagnosis.
What should we do to confirm the diagnosis?
Before starting the investigations, specialized screening tests are carried out to flag appropriate patients based on their risk for OSAS. The STOP-BANG tool and the Epworth Sleepiness Scale (ESS) are the primary screening tests used in this process.
If a diagnosis of OSA is suspected, the patient can be further evaluated to rule out other differential diagnoses and establish the severity of the condition. Local resources and the likelihood of diagnosis determine the level of investigation.
Polysomnography testing is the most widely used diagnostic technique for OSA. Multiple sleep variables, such as sleep patterns (EEG), rapid eye movements (EOG), neck muscle tonicity (EMG), cardiac rhythm (ECG), oxygen saturation (pulse oximetry), airflow, thoracic and abdominal movement, and other ventilatory variables, can all be quantified using this method.
In addition, a simple overnight pulse oximetry test can be done at home to measure the number of desaturations per hour, which will be demonstrated cyclically with a typical sawtooth appearance. This helps to determine the severity of sleep apnea with the help of the apnea-hypopnea index (AHI). AHI is defined by the number of episodes of apnea or hypopnea per hour and classifies the severity as,
• AHI <5 – Normal
• AHI 5 – 15 – Mild OSA
• AHI 15 – 30 – Moderate OSA
• AHI >30 – Severe OSA
What can OSAS possibly lead into?
You must be wondering how bad OSAS can be, other than being late to work and feeling a bit sleepy during the daytime.
Numerous studies have shown that severe complications are linked with obstructive sleep apnea syndrome. These include cardiovascular disease, metabolic syndrome, and type 2 diabetes mellitus. Systemic hypertension, atherosclerosis, congestive heart failure, cardiac arrhythmias, myocardial ischemia and infarction, and stroke are manifestations of cardiovascular complications.
In between 50 and 70 per cent of obstructive sleep apnea patients, systemic hypertension is seen, and it has been demonstrated to be a risk factor for developing hypertension independent of age and obesity. The degree of nocturnal desaturation or the apnea-hypopnea index can both be used to predict atherosclerosis in people with OSA. About 10% of OSA patients experience bradyarrhythmia, and they also have a higher risk of developing nocturnal complex arrhythmias and premature ventricular contractions (PVCs), and in the absence of conduction disorders in these patients, atrioventricular blocks and asystole may also develop. Acute myocardial infarctions (AMIs) can result from coronary artery disease (CAD), which is twice as common in OSA patients.
OSA has demonstrated a stronger association with stroke than any other cardiovascular disease, and these patients are at a higher risk of suffering a stroke and dying.
The metabolic abnormalities that characterize the metabolic syndrome may be exacerbated by OSA, potentially resulting in type 2 diabetes mellitus. These alterations may be brought on by elevated glucose levels and increased insulin resistance in these patients.
Road traffic accidents are a big concern for OSA patients, in addition to the above-mentioned medical complications. So, they should avoid driving until the condition is completely resolved or managed.
Can we prevent OSAS?
Prevention is often achieved by limiting the body positions during sleep. In the supine posture, sleep apnea is more severe. As a result, the patient should avoid sleeping on their back by employing devices like a snoring ball or a gravity-activated position monitor.
Patients with severe obesity may benefit from sleeping upright and using pillows made explicitly for that purpose.
What are the treatment options available?
Obstructive sleep apnea management depends on the severity of obstructive sleep apnea. Patients with mild OSA caused by obesity, alcohol abuse, or sedative usage are typically counselled to address these issues. Weight loss is encouraged, as is quitting smoking and alcohol, avoiding sedatives, sleeping in a lateral posture with the head elevated on the bed, and avoiding being overtired throughout the day.
As we can see with Mr. Kareem, those with moderate to severe disease are treated with positive airway pressure devices or surgery, if indicated.
Continuous positive airway pressure (CPAP) is the most common and reliable method of treating sleep apnea. Through a mask, it delivers air with slightly greater pressure than the atmospheric pressure and splints the airway such that it cannot be blocked. This way, the symptoms, daytime alertness, quality of life, and patient prognosis are improved. In addition to CPAP, other devices such as auto-CPAP or BiPAP are also available.
Typically, surgery is considered only when all other forms of treatment have failed. These are tissue removal surgeries such as uvulopalatopharyngoplasty, tissue shrinkage, jaw repositioning surgeries, tonsillectomies, and weight-loss surgery (bariatric surgeries).
Revisiting the patient
So, let’s get back to our patient and see what progress we have on his sleep apnea.
After four months of using a CPAP device, Mr. Kareem returns and reports that his daytime hypersomnolence has improved. With a 7 kg weight decrease, he has been exercising more and watching what he eats. He claims that he uses the mask every night for at least 4 hours, initially finding it tough to tolerate but eventually becoming more tolerant. He uses a humidifier, which has made a slight difference.
In conclusion
OSAS is a form of sleep-disordered breathing characterized by upper airway collapse resulting in obstructive apneas and hypopneas combined with excessive daytime sleepiness. Frequently, patients are easily diagnosed through a careful history and a physical examination, but occasionally screening tests and investigations are necessary to rule out differential diagnoses. Proper and timely treatment is essential to prevent complications, particularly hypertension. Treatment options include simple lifestyle changes, positive airway pressure devices, or surgery, depending on the severity of obstructive apnea.
References
- Kumar and Clarke’s clinical medicine, 10th Edition
- Davidson’s Principles and Practice of Medicine, 23rd Edition
- https://www.mayoclinic.org/diseases-conditions/sleep-apnea/symptoms-causes/syc-20377631
- https://www.mayoclinic.org/diseases-conditions/obstructive-sleep-apnea/diagnosis-treatment/drc-20352095
- https://emedicine.medscape.com/article/295807-clinical#b3
- https://emedicine.medscape.com/article/295807-differential#1
- https://www.nejm.org/doi/10.1056/NEJMra1500587
- https://emedicine.medscape.com/article/295807-clinical#b5
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4877315/