Pathophysiology
P-I-4. Hypertension, Case 4
高血圧 症例4
A 44-year-old bus driver causes a road traffic accident which does not involve serious injury. Investigation reveals that the driver very often wakes up with a headache, feels very tired in the morning, and is often sleepy during the day. He has no other medical complaints, is not on medication. Despite his obesity, he does not have time to exercise and does not follow a slimming diet. He does not smoke, and he drinks only a little alcohol, occasionally; however, due to his constant somnolence, he drinks at least 5 or 6 cups of strong coffee every day. It has been suggested that the accident may have been caused by the driver falling asleep for a short time. The investigation involves the participation of the employee’s occupational health doctor. The result of the examination is the following: significant obesity, body weight: 105 kg, height: 165 cm. Blood pressure: 170/95 mmHg measured on both arms, heart: rhythmic, clear cardiac sounds, no murmur can be heard, HR: 98 beats per minute. Over the lung normal respiration. The abdomen is protruding, soft, palpable, no sensitivity or resistance. Liver is enlarged, not sensitive. The peripheral blood vessels are well palpable, no audible murmur over the carotid arteries or the femoral artery.
In earlier years, blood pressure readings taken in the occupational health doctor’s office were normal; there was only once a reading of 150/85 mmHg, but the follow-up examination found normal values again. The patient has recently gained significant weight. Two years ago, his body weight was 85 kg. This significant weight gain is seen by the patient as resulting from too little exercise, sedentary work, and the physique that runs in the family.
He goes to bed in time, but often sleeps badly. According to his wife, he snores very much, and occasionally snorts loudly in his sleep. He mostly lies on his back when sleeping. In response to question, he does not mention chest complaint or intense palpitation; there was no loss of consciousness, dizziness, visual disturbance, or nausea.
Examination performed: ECG – sinus rhythm, HR: 72 beats per minute, regular curve, no sign of ischemia.
Significant findings in routine laboratory test: total cholesterol level: 6,9 mmol/l, slightly increased SGOT, SGPT levels, everything else is within the reference range.
Key Quotes & What They Tell Us
| Quote / Value | Interpretation |
|---|---|
| “wakes up with a headache, feels very tired in the morning, and is often sleepy during the day” | Classic symptoms of obstructive sleep apnoea (non-restorative sleep, daytime somnolence) |
| “he snores very much, and occasionally snorts loudly in his sleep … lies on his back” | Witnessed snoring and apnoeic snorting → strongly suggestive of obstructive sleep apnoea |
| Weight 105 kg, height 165 cm (BMI ≈ 38.6); recent gain from 85 kg | Significant, worsening obesity — a key risk factor for both OSA and hypertension |
| BP 170/95 mmHg now, previously normal readings | New-onset (secondary) hypertension temporally linked to weight gain and sleep symptoms |
| Total cholesterol 6.9 mmol/L; mildly elevated SGOT/SGPT | Dyslipidaemia and likely non-alcoholic fatty liver → features of metabolic syndrome |
| “the accident may have been caused by the driver falling asleep” | Daytime sleepiness causing real-world impairment → occupational/safety hazard |
Key Points
- Diagnosis: Secondary hypertension due to obstructive sleep apnoea, on a background of obesity and metabolic syndrome.
- Pathophysiology: Repetitive airway collapse → intermittent nocturnal hypoxia → chronic sympathetic activation → sustained daytime hypertension.
- Contributors: Marked recent weight gain, dyslipidaemia, and fatty liver.
- Next step: Polysomnography (sleep study) to confirm OSA; treat with weight loss and CPAP.
- Lesson: OSA is an important, reversible cause of hypertension and a major cause of dangerous daytime sleepiness.
一問一答
▶What is the diagnosis in an obese patient with morning headache, daytime sleepiness, loud snoring, and new hypertension?
Secondary hypertension due to obstructive sleep apnoea (OSA).
▶What are classic symptoms of obstructive sleep apnoea?
Morning headache, non-restorative sleep, daytime somnolence, loud snoring, and witnessed apnoeic snorting.
▶What is the pathophysiology linking OSA to hypertension?
Repetitive airway collapse → intermittent nocturnal hypoxia → chronic sympathetic activation → sustained daytime hypertension.
▶What is the confirmatory test for OSA?
Polysomnography (a sleep study).
▶What is the main treatment for obstructive sleep apnoea?
Weight loss and CPAP (continuous positive airway pressure).
▶Why is obesity a key risk factor for OSA?
Excess pharyngeal/neck soft tissue narrows the upper airway, promoting collapse during sleep.
▶What features in this patient indicate metabolic syndrome?
Obesity, hypertension, dyslipidaemia (cholesterol 6.9 mmol/L), and likely non-alcoholic fatty liver (elevated SGOT/SGPT).
▶Why is OSA an important cause of hypertension to identify?
It is reversible — treating it can improve blood pressure control.
▶Why is daytime sleepiness from OSA a major occupational hazard?
It impairs alertness and can cause accidents (e.g., falling asleep while driving).
▶Why does sleeping on the back worsen OSA?
Gravity allows the tongue and soft palate to fall back, further obstructing the airway.
▶Why does the new-onset hypertension correlate with recent weight gain in this patient?
Weight gain worsened OSA and metabolic syndrome, both of which raise blood pressure.
▶What does the mildly elevated SGOT/SGPT suggest in this obese patient?
Non-alcoholic fatty liver disease as part of the metabolic syndrome.
▶Why does intermittent nocturnal hypoxia increase sympathetic tone?
Recurrent apnoea-related hypoxaemia triggers chemoreflex-mediated surges in sympathetic activity that persist into daytime.
▶How does CPAP treat OSA mechanistically?
It delivers positive airway pressure that splints the upper airway open, preventing collapse and nocturnal hypoxia.
▶Why does this patient drink 5–6 cups of strong coffee daily?
To counteract his constant daytime somnolence caused by OSA-disrupted sleep.
▶What is the patient's BMI and why is it significant?
About 38.6 kg/m² (105 kg, 165 cm) — significant obesity that drives both OSA and hypertension.
▶Why might routine office BP have been normal before in this patient?
Hypertension was recent and secondary to progressive weight gain/OSA; earlier readings predated those changes.
▶Why is weight loss a key part of OSA and hypertension management here?
Reducing weight decreases airway obstruction and improves metabolic syndrome, lowering blood pressure.
▶What is the atherogenic lipid finding in this patient?
Elevated total cholesterol (6.9 mmol/L) indicating dyslipidaemia.
▶Why is the ECG normal despite significant hypertension and OSA?
Hypertension is recent, so no chronic ischemic or hypertrophic ECG changes have yet developed.