The blood pressure machines in supermarkets are generally not reliable because it’s impossible to know how well-maintained they are. But the kits for home use are, and hypertension specialists recommend them for anyone who needs to monitor blood pressure regularly.
“I encourage patients to do home monitoring,” said Dr. Randall Zusman, director of the hypertension service at Massachusetts General Hospital. “It gives patients feedback and tends to promote compliance” with medications and efforts to stick to a good diet and exercise program. It may also give more typical readings than those obtained in a doctor’s office because a person is less likely to exhibit “white coat hypertension,” the rise in blood pressure due to the stress of being at the doctor’s office.
Studies in recent years have shown that the good home kits correlate well – within 5 millimeters of mercury – with the readings obtained in doctors’ offices, said Dr. Roger Blumenthal, director of preventive cardiology at Johns Hopkins Medical Institutions.
High blood pressure is a major risk factor for stroke, heart attack and kidney disease. Normal blood pressure is defined as a reading of 120 mm over 80 mm. High blood pressure is a reading of 140 systolic (the upper number) over a diastolic (the lower number) reading of 90. Numbers between 120 over 80 and 140 over 90 are a potential sign of pre-hypertension and may suggest treatment is necessary. Nearly everyone over 55 will eventually become hypertensive, said Zusman.
It’s a good idea to bring your home kit to the doctor to calibrate it with the doctor’s machine. According to the June, 2003 issue of Consumer Reports, home kits – which cost $35 and up – that use automatic arm cuffs were the most reliable; those using wrist cuffs or arm cuffs that had to be inflated by squeezing a bulb were less dependable.