Primary Care Corner with Geoffrey Modest MD: Orthostatic Hypotension Revisited

By Dr. Geoffrey Modest

I decided to repost a blog from 11/12/14 on initial orthostatic hypotension, with a few additional comments, because I am finding this issue to be so common in my older patients. I am concerned that there is often a combination of pretty common age- and morbidity-related problems, often with some combination of medication adverse effects (some of the most egregious being a- or b-blockers, diuretics, narcotics, vasodilators including calcium-channel blockers or hydralazine), alcohol, morphine, dehydration (esp in the hotter times of the year), autonomic neuropathy (esp from diabetes), and just the plain old decrease in baroreceptor response with aging. And, I am a little concerned about being overaggressive with application of the SPRINT trial results to the elderly (which, of note, excluded diabetics), suggesting benefit for more aggressive BP management in older patients. (See http://blogs.bmj.com/bmjebmspotlight/2015/11/19/primary-care-corner-with-geoffrey-modest-md-tighter-blood-pressure-control-the-sprint-trial/. For a historical review of initial orthostatic hypotension, see Wieling W. Clinical Science 2007; 112: 157.

Here is the blog from 11/12/14:

Circulation had an article on the prevalence of orthostatic hypotension in Ireland (see Finucane C. Circ 2014; 130: 1780). This study involved 4475 community-based people over age 50 from a nationally representative cohort study (TILDA — The Irish Longitudinal Study on Ageing — that’s how they spell “aging”…), recording blood pressure and pulse response to standing. They looked at initial orthostatic hypotension (defined as a BP decrease of >40 mmHg systolic or >20 mmHg diastolic within 15 seconds of standing and associated with symptoms of cerebral hypoperfusion), and typical orthostatic hypotension (defined as a BP decrease of >20 mmHg in systolic or >10 mmHg in systolic after 3 minutes of standing).

Findings:

  • Cohort baseline characteristics: average age 62.8, 51.8% female, 19% smokers, 7.5% diabetes, 34.5% hypertensive, total of <11% with any cardiovascular history — so pretty healthy
  • Initial orthostatic hypotension was found in 32.9% of those >50yo, no difference by age or gender
  • Typical orthostatic hypotension was found in 6.9% overall, increasing from 4.2% in 50 yo to 18.5% in those >80yo
  • Prevalence of failure to return to baseline blood pressure after standing 40 seconds increased with age: from 9.1% in 50 yo to 41.2% in those >80yo

So, a few points (some added since the original blog).

  1. The pathophysiology and epidemiology of initial orthostatic hypotension is somewhat different from the typical orthostatic hypotension. With initial orthostatic hypotension, there is a rapid temporal mismatch between cardiac output (there is an immediate increase in heart rate due to inhibition of vagal activity within seconds of standing, stable stroke volume, and a sharp increase in cardiac output). But the rapid fall in blood pressure after standing (approx 25 mmHg in several studies) is most likely from a marked decrease in vascular resistance (which is around 40% in studies). This typically happens in thin young people (who need to dangle their legs prior to getting out of bed, for example) and those on a-blockers (including reports with tamsulosin for BPH). The typical orthostatic hypotension results from standing, pooling of blood in the legs, decreased venous return, which usually triggers a baroreceptor reflex inducing vasoconstriction (so the usual change is a decrease of about 5 mmHg systolic and a slight increase in diastolic, which rapidly reverses with rapid vasoconstriction). But without this vasoconstriction, there is subsequent decrease in cardiac output and hypotension. This tends to happen in older people who have diminished baroreceptor responsiveness, and in those with hypovolemia, on aggressive diuretics, tricyclic antidepressants, etc.
  2. I don’t want to over interpret this study. The population studied was racially and ethnically pretty uniform. There was no information on whether there was a difference if they had underlying hypertension or what medicationsthey were taking. There are no data on whether the typical orthostatic hypotension was symptomatic. And the limited data available do not all point to asymptomatic hypotension as a cause of falls, for example.
  3. BUT, to me, these numbers are very impressive. I do typically check orthostatics on my elderly patients and very often do find marked hypotension on standing, sometimes symptomatic and sometimes not. When the patient is symptomatic (either by history at home, e.g. when standing, or in the office), I do not hesitate to back off on BP meds (or if they are not on them, I sometimes need to use fludrocortisone or midodrine and suggest high salt diets to raise the blood pressure). In asymptomatic patients, the decision is harder. In general, I am pretty concerned that they may have an even more exaggerated hypotensive orthostatic response if they are a little dehydrated (hot summer day), or don’t drink their usual amounts of fluids, or have GI fluid loss through vomiting/diarrhea, or even postprandially, when blood pressure tends to be lower. So, I use an even less stringent definition than the above: if an elderly patient has a sitting blood pressure with systolics in the 120-140 range which decreases to the 90-100 range even though asymptomatic at the time I am seeing them — I’m just not sure that this fully reflects their condition at home at different times (e.g. hot weather) and I am pretty concerned about falls, as well as potential cognitive decline (see http://blogs.bmj.com/bmjebmspotlight/2015/04/23/primary-care-corner-with-geoffrey-modest-md-too-low-blood-pressure-and-cognitive-decline-in-elderly/ ), or decreased coronary perfusion because of low diastolics.
  4. And my experience does pretty much reflect the data from the Irish study above, where initial orthostatic hypotension happened in 1/3 of the patients over age 50 and may not return to baseline for quite some time
  5. What does this mean in light of the SPRINT trial, where even those >75yo (mean age 80) benefited clinically from lower blood pressures? For me, it means a few things:
  • I need to have a dependable blood pressure reading: the blood pressure recorded by the medical assistants after they have the person walk from the waiting room into the vital signs area is often 30+ mmHg more than I get with a repeat manual reading when the patient has been sitting in my exam room for a few minutes (which may speak to the level of deconditioning of many of my older patients, and even a good number of younger ones…). And I do regularly check orthostatics both right after the person stands and after a few minutes. I also try to get home-based BP recordings, which in some cases is much lower than I find in the clinic (see http://blogs.bmj.com/bmjebmspotlight/2015/01/15/primary-care-corner-with-geoffrey-modest-md-uspstf-recs-on-ambulatory-blood-pressure-monitoring/ for example)
  • And, if an older nondiabetic person can achieve a blood pressure of 120-130/70 range without exaggerated initial or postural hypotension leading either to symptoms or a systolic <100-110 range, I do think that this goal is clinically preferable, per the SPRINT trial.

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