I know I wrote about the healthcare system in America recently, so please don’t read too much into the fact that today I’m writing about medicine. It is purely coincidental…I think. It just so happens that meds are on my mind for all sorts of reasons. I will start with the most personal of those. I am expecting the delivery of two prescriptions today and I am in short enough supply of those two so that I cannot pack my bag for my trip to New York City to see my kids, etc. next week. You see, the one affliction that my doctor thinks I have is high blood pressure. I think that is debatable since the measurement of blood pressure is such an art rather than a science, and because of that I am only somewhat convinced that I need any meds. Nevertheless, I have submitted to medication just to keep everybody happy. The doctor I have had since moving out here is a nice enough Vietnamese woman who seems to love tweaking my meds every time I come in. My diastolic pressure has been below the 80 mm/Hg (where it should be), but my systolic pressure has stubbornly stayed just above 140 mm/Hg (20 mm/Hg higher than they like to see). That, and my resting heart rate is extraordinarily low in the 40’s beats/min.
I have taken much issue with the measurement of blood pressure, but understand that this “silent killer” afflicts about half of the adult population of the United States and contributes to the deaths of perhaps 600,000+ people per year. The history of blood pressure measurement is quite interesting and begins in ancient civilizations, where physicians first recognized the importance of heart pulse in health assessment. Both ancient Chinese medicine and Egyptian medicine shows that healers understood the importance of pulse in assessing the heart’s function. The seminal scientific work on blood pressure came from William Harvey’s writings on blood circulation in 1628, but it wasn’t until 1733 that Stephen Hales conducted the first actual blood pressure measurement, performing a rather gruesome experiment involving a brass pipe and a horse’s artery. In the Nineteenth Century (1828) Jean Poiseuille began using a mercury-filled tube, thereby introducing the “millimeters of mercury” (mm/Hg) measurement still used today. So, let’s start by observing that the current methods are based on two hundred year-old methods.
Over the ensuing centuries, devices such as the kymograph and the sphygmomanometer, using (eventually) an inflatable cuff that wrapped around the arm, made blood pressure measurement rather ubiquitous. In 1905, Nikolai Korotkoff discovered the sounds (what I call the whoosh and goosh) that differentiated systolic and diastolic blood pressure using a stethoscope and arm cuff. These days there are more advanced technologies available (wireless, smartphone-linked, cuffless, etc.), but the basic cuff and whoosh/goosh are still most often used in one form or another, and this is troubling. Different size cuffs seem to cause very different readings and yet there are a really only two sizes. Taking the measurement on one arm versus another makes a difference. Taking it in the upper arm versus the ankle or finger seems to matter. And most of all, it seems to constantly change based on the flimsiest of causes (moving around, not elevating the arm enough, talking, sitting up straight, etc., etc.). And it all seems to get distilled to a pressure reading based on a device that contains mercury in a glass tube which will rise in the tube, and thereby give us the height of the mercury column in millimeters (mm/Hg). The good news is that it is standard worldwide. The bad news news is that it seems a pretty inaccurate system for measuring something so vital to our health.
I am not the first person to question the accuracy of modern methods used in capturing blood pressure. They say that Mercury Sphygmomanometers (if properly calibrated…who knows what that means) are accurate to ±3 mmHg but alas, mercury is too toxic to continue to be widely used. The aneroid devices that do not use liquid mercury are both less accurate and also prone to mechanical wear, physical shock and generally need regular recalibration to be anywhere near accurate. Automated oscillometric devices give readings of ±5 mmHg, but still suffer from the device-related failures due to calibration status, cuff size appropriateness, device maintenance and age as well as technique-related factors like proper patient positioning, being seated with back supported, having your feet flat on floor and your arm at heart level….with prior rest of at least 5 minutes, no talking during measurement, and the taking of multiple readings with 1-2 minute intervals. There is even variations caused by cuff placement, which should be 2-3 cm above antecubital fossa (your elbow depression), centered over your brachial artery (you know how tough that can be to find based on poking and prodding by blood technicians), and that there is “appropriate tightness”.
These causes for measurement error have been empirically proven to be significant and often cumulative. Systematic errors like incorrect cuff size (Too small: Falsely high readings +10-40 mmHg and Too large: Falsely low readings -10-30 mmHg), Positioning errors (Arm below heart level: Falsely high readings +10 mmHg and Arm above heart level: Falsely low readings -10 mmHg), Technical errors (Deflation rate too fast: Underestimated systolic and overestimated diastolic versus Deflation rate too slow: Patient discomfort affecting readings), not to mention the random errors like patient anxiety, recent physical activity, fullness of the bladder, ambient temperature, and even background noise. Measurement in aging patients can also be heavily influence by things like vessel stiffness and arrhythmias (affecting over 70% of patients over 60).
What this should be telling us is that this is a VERY inexact science and that medicating for a reduction of blood pressure is tricky because different drugs impact systolic versus diastolic and pulse rate is also at play from the same drugs. So, now I have 140/80 mm/Hg blood pressure with a 49 resting heart rate (somewhat low due to good genetics and somewhat low due to some combination of my meds). My meds include a fluctuating dosage of Carvidilol (a beta-blocker with added alpha-blocking capability, and that is way too complicated to understand or explain), Ramipril (an ACE inhibitor, even though my ACE has always been normal), Hydralazine (a direct vasodilator), Clonadine (a centrally-acting agent that lowers things like heart rate) and Furosemide (a loop diuretic that makes me lose 3 liters of fluid each morning). I don’t feel any different if I miss any of these other than the diuretic (which I skip when I am traveling or have to be somewhere like court where having to pee badly is not a good look).
I seem to be OK with these meds, but I also understand that sustained high systolic pressure (if, indeed, I have that) can lead to all sorts of nasty things starting with stroke and heart damage. Not far behind that are things like renal damage, ocular damage, vascular damage and even cognitive decline…your basic health nightmares. I am 71 years old now and statistically, I ‘m expected to live another nine years (God willing and the creek don’t rise). I don’t want any of those bad things to happen to me, but I especially don’t want to stroke out, so I will continue to let little Ms. Saigon tweak my meds and confuse the online pharmacy folks, who always seem to deliver too much or loo little of the wrong meds to me, thanks to all the adjustment confusion. Everyone has his/her medicinal reality and this is mine. Maybe I should just lose more weight (I’m trending down right now anyway) and make this all go away?