Pseudohypertension

Pseudohypertension is a falsely raised cuff blood pressure caused by arteries that are too stiff or calcified to be compressed by the cuff. The cuff reading exceeds the true intra-arterial pressure, usually by 10 mm Hg or more.

It occurs in older adults, in diabetes, in chronic kidney disease and on dialysis, and with medial calcification (Mönckeberg sclerosis). It is uncommon, but it is a classic cause of apparent resistant hypertension without organ damage.

The harm comes from overtreatment: orthostatic hypotension, falls, syncope, cerebral and renal hypoperfusion and acute kidney injury.

An oversized difference may also arise from a cuff that is too small for a large arm, which is a technical error and not true pseudohypertension.

Pathophysiology. A rigid calcified brachial artery stays open at cuff pressures that would collapse a normal artery. Auscultatory readings of systolic and diastolic pressure are therefore over true intra-arterial values.

Oscillometric devices are less affected but not immune.

• High cuff pressures, often over 200/110 mm Hg, with no left ventricular hypertrophy, retinopathy or albuminuria.
• Apparent resistant hypertension on several drugs, with dizziness, falls, syncope, fatigue, confusion or angina on treatment.
• Stiff, palpable, "pipe stem" radial or brachial arteries.
• Osler sign: the radial artery remains palpable when the cuff is inflated over the systolic pressure. It is unreliable alone.

Red flags.

• Resistant hypertension with no target organ damage
• Symptomatic hypotension or falls on treatment
• Acute kidney injury or syncope after intensifying therapy
• Large gap between cuff and home or ambulatory readings
• Arterial calcification on X-ray or CT
• Severe pressures over 200/120 mm Hg without organ damage

• Osler manoeuvre. Inflate the cuff over systolic pressure and palpate the radial artery. A palpable artery supports the diagnosis.
• Intra-arterial measurement (radial or brachial) is the reference method. A difference of 10 mm Hg or more in systolic pressure confirms it.
• Comparison. Compare cuff readings with ambulatory or home monitoring on a validated oscillometric device, and with intra-arterial pressure in the same patient.
• Imaging. Plain X-ray of the arm or hand, or CT, shows arterial calcification.
• Organ damage review. ECG, echocardiography, fundoscopy, creatinine, eGFR and urine albumin to creatinine ratio. The absence of damage despite very high readings supports it.
• Orthostatic pressure at each visit.

Differential diagnosis.

• True resistant hypertension
• White coat hypertension
• Wrong cuff size and measurement technique error
• Arm position error (arm lower than heart level)
• Atherosclerotic subclavian or brachial stenosis (difference between arms)
• Auscultatory gap
• Autonomic and other causes of orthostatic hypotension
• Overtreatment of true hypertension

• Confirm with intra-arterial measurement before escalating treatment for apparently resistant hypertension without organ damage.
• Withdraw excess treatment when true pressure is at target or low. Stop the most recently added drug or the drug causing symptoms first, then reduce stepwise, checking seated and standing pressure with a method calibrated to the patient's intra-arterial reading.
• Use a validated follow up method: oscillometric or ambulatory monitoring checked once against intra-arterial pressure, and record the individual difference in the notes.
• Treat true hypertension if present to the usual targets, once the correct pressure is known.
• Treat contributors to calcification. Control phosphate, calcium and parathyroid hormone in chronic kidney disease, optimise glucose, and avoid calcium and vitamin D excess.
• Avoid repeated escalation of antihypertensive drugs based on cuff readings alone.

Special groups. In dialysis patients intra-arterial confirmation is most useful, because calcification is common and overtreatment causes intradialytic hypotension.

Monitoring. Seated and standing pressure at each visit, symptoms of hypotension, creatinine and potassium after any drug change, and a repeat comparison with intra-arterial pressure when the clinical picture changes.

Referral and escalation. Refer to a hypertension specialist or cardiology for intra-arterial measurement. Urgent for syncope, acute kidney injury or symptomatic hypotension.