When your white coat is the problem. Though not the case with Mr. Brown, a patient’s elevated readings could be a case of white coat hypertension—a conditioned response in some patients that is probably the result of anxiety in the medical setting.10 Patients with white coat hypertension have significantly less risk of death and reduced target organ damage than patients with truly resistant hypertension.11,12
If you suspect that a patient of yours has white coat hypertension, you can test your hypothesis by encouraging him or her to buy a blood pressure monitor to use at home, keep a log of the readings, and bring the log in to the next appointment. Improved technology has made home blood pressure monitoring an important tool in the treatment of high blood pressure.13-15
According to a 2008 statement issued jointly by the American Heart Association, the American Society of Hypertension, and the Preventive Cardiovascular Nurses Association, “There is a rapidly growing literature showing that measurements taken by patients at home are often lower than readings taken in the office and closer to the average blood pressure recorded by 24-hour ambulatory monitors, which is the blood pressure that best predicts cardiovascular risk.”14
Arm monitors are the most accurate because they measure brachial artery blood pressure.14 Most wrist monitors have not been validated in studies, but obese patients who cannot find a properly sized cuff may need to use them.14 Finger devices should never be used.14
Sometimes technique is at fault. To ensure that you get proper readings when your patient is in the office, advise the nursing staff not to take a patient’s blood pressure for at least 5 minutes after bringing him or her to an exam room. Specifically, the nurse can either make blood pressure measurement the last thing she (or he) does when “rooming” the patient, or she may prefer to go back to the exam room a few minutes after the patient is there to take the reading. The nurse should take care that the cuff is the right size and that the pressure is taken with the patient’s arm at heart level. In hypertensive patients, placing the arm below the horizontal in the dependent position can raise blood pressure 23/10 mm Hg.1,16,17
Newer blood pressure monitoring devices for the office are available that obviate artificially high readings caused by errors in technique and by white coat syndrome. Researchers have found that readings taken with the BpTRU automatic device, which obtains and records 5 blood pressure readings over a 5-minute period, are lower than those taken by office personnel, and that the white coat effect is eliminated.18,19
One pseudo-resistant case solved. At Mr. Brown’s next visit, you review his pill calendar with him and note that his blood pressure is now running 138/88 mm Hg and he is within his target goal of less than 140/90 mm Hg.
If Mr. Brown’s blood pressure control had continued to be suboptimal even after you’d taken steps to address cause(s) of pseudo-resistance, you would have had to shift gears and consider his case one of resistant hypertension.1
Consider resistant hypertension
Causes of resistant hypertension include lifestyle factors, side effects of medications, and secondary causes.5,6 Tobacco use, obesity, lack of exercise, a high sodium diet, and alcohol consumption can all contribute to hypertension.1,5,6,20,21 Dietary sodium in particular has significant adverse effects. Reducing dietary sodium not only reduces mortality, but has positive cardiovascular effects separate from blood pressure reduction, such as improved endothelium-dependent vasodilation.22-24
Medications including nonsteroidal anti-inflammatory drugs (NSAIDs), oral contraceptives, sympathomimetics, glucocorticoids, and black licorice (found in some herbal supplements) may all raise blood pressure.5 Medications and other substances associated with increased blood pressure are listed in the TABLE. A search for such products, with changes or discontinuations that are clinically appropriate, should be part of any evaluation for resistant hypertension.
CASE 2 Ms. Stevens is a 30-year-old woman who was diagnosed with high blood pressure 7 months ago. She is currently taking triamterene-HCTZ 37.5/25 mg daily, amlodipine 10 mg daily, and metoprolol succinate 100 mg daily. She is compliant with medication, sticks to a low-sodium diet, and exercises 5 days a week. She does not drink alcohol. A review of her chart tells you her baseline serum chemistries, chest x-ray, and urinalysis are all normal. Today’s blood pressure taken in the sitting position after a 5-minute rest is 160/92 mm Hg. How should you proceed?