Researcher: Turn Off Cell Phones at BP Visits

SAN FRANCISCO—Hypertensive patients who take cell phones calls during blood pressure (BP) check-ups in the doctor's office may experience significant rises in BP, according to Italian investigators.

Systolic and diastolic readings may rise by 7.1 and 4.7 mm Hg, respectively, the researchers reported at the American Society of Hypertension 28 Annual Scientific Meeting.

“The blood pressure increase we detected is not negligible from the clinical point of view,” said researcher Giuseppe Crippa, MD, a staff physician the Bravi of Guglielmo da Saliceto Hospital, Piacenza, Italy. “Large surveys have shown that a blood pressure reduction of 2 mm Hg is highly significant for the risk stratification and the prognosis of the patients.

The aim of the study was to investigate the effect of telephone rings and conversations during BP measurements. “It is important to know whether the blood pressure reading we measure is altered by external stimulations such as the ‘intrusion' of a phone that rings in an inappropriate situation,” he said.

Dr. Crippa and his colleagues conducted a study with 94 mild-to-moderate hypertensive patients.  The mean age of the patients was 53 years, and 49 (52%) of 94 patients were female. All the patients were taking antihypertensive medications. At the start of the study, investigators asked subjects about their habitual use of cell phones. They recorded the mean number of daily calls and the patients' attitudes about turning off their phones. 

The phone numbers of all the subjects were recorded and during one of the two consecutive visits the patient's mobile phone number was dialed three times by one of the investigators. The phone showed that the person calling was unknown. This part of the test was considered complete if the subject answered and spoke on at least one of the three phone calls made by the investigator.

Dr. Crippa said all the subjects were randomly assigned to receive phone calls during the first or the second series of automated measurements. In each of these series of automated measurements, an initial BP reading was recorded. The subjects would remain alone and seated in a comfortable armchair in the consulting room.  The investigators then obtained the mean systolic and diastolic pressure readings and heart rate with and without phone calls.

The study showed that the systolic pressure rise was less drastic in patients who were used to participating in more than 30 phone calls per day. There may be two possible reasons for this, he said. First, a subset of patients who were more accustomed to cell phone use were younger, and younger people may be less prone to be disturbed by telephone intrusions. Second, it is possible that people who make more than 30 calls per day may feel more reassured if the mobile phone is activated.

Optimal BP is below 120/80 mm Hg, so it is possible that a temporary increase of 7/5 mm Hg is not harmful for normotensive subjects, he said.  “Conversely, an even mild increase in blood pressure in patients with blood pressure levels above 140/90 mm Hg should be considered as a negative,” he said.

The use of mobile phones has had an exponential growth and is often an indispensable communication tool for business and social relations, he said. However, the study suggests that turning them off at a doctor's visit may be advisable because taking cell phone calls shortly before having a BP reading may lead to less-than-optimal measurements.

“This phenomenon might lead to misinterpretation and overestimation of the real patients' blood pressure status,” Dr. Crippa told Renal & Urology News. “The great majority of the patients recruited for the study were not used to turning off the mobile phone during a medical examination and easily answered the calls. We believe that it is important to advise all patients to  turn off  their phone before entering the doctor's office.”

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