Serial blood pressures were automatically recorded during the one-minute test. Our average peak blood pressure during the last ten seconds of immersion was 235/135. The extreme discomfort of this cold exposure served to make it the longest minute of your life.
Now for our surprise - our average blood pressure response during the last ten seconds of subtracting 7's was 245/140!
We were all healthy, 25-year olds. We were told by the exercise physiologist in charge that this was a typical, normal response.
The results of this simple test have stayed with me throughout my 10 years as a United States Air Force research scientist and 23 year as family doctor.
Never did I or any of my well-trained staff talk to a patient while taking their blood pressure and we usually counselled "think nice thoughts" during the blood pressure reading and invariably took pressures only while the patient had been recumbent for at least several minutes.
Now as a patient, when I go to my family doctor my blood pressure is usually recorded while I am standing on the scale and a nurse is asking me how I like the weather. Without being a bore I try to make the point to both office staff and the doctor of how much simple conversation can influence the blood pressure. Apparently they all have missed that bit of environmental physiology during their training.
If you just happen to be a Type A personality, the effect of talking during the taking of blood pressure can be extreme and even while this patient is quiet, he is mentally composing his next response and the "wheels" are madly turning.
Now that we have learned more about this, we find that everybody's blood pressure tends to spike with speaking. Also, speech intensity and volume as affected by emotion or high ambient noise levels can greatly augment this tendency. Other contributory factors are content of the talk and social quality of the audience.
Your typical Type A is a terrible listener because he or she tends to think about what they are going to say next and how best to interject their points in a discussion. Their speech is often forceful from a pattern of expelling air while talking. These speech clues are vital to diagnosing Type As and getting them to treatment before serious damage is done.
Long have we wondered why some people have strokes and heart attacks despite having a diagnosis of normal blood pressure and this type A personality tendency with a lifetime of blood pressure surges could be one reason.
Their blood pressure, properly taken in a quiet environment without the mental challenge of communication, is perfectly normal. A 24-hour blood pressure assessment also may be normal, leading their doctor to make a falsely normal diagnosis while the cumulative effect of years of blood pressure spikes to extreme levels has been silently damaging their blood vessels, paving the way for atherosclerosis.
I routinely added verbal challenge to my routine blood pressure testing by simply inviting conversation during the final blood pressure determination, thereby picking up these verbal hypertensives and being able to initiate a much needed treatment plan.
I still find it difficult to accept that of all the testing I have personally experienced such as explosive decompression, parachute, centrifuge, heat chamber and ejection seat training, my greatest blood pressure response came from subtracting 7s serially from 100.
Duane Graveline MD MPH
Former USAF Flight Surgeon
Former NASA Astronaut
Retired Family Doctor