Hello, welcome back to the "Hypertension Medical Course." I am Jessica.
In the previous lesson, we discussed that the essence of hypertension
is a non-steady state, which is rather abstract. However, when facing a
specific patient, doctors must give clear conclusions, such as whether
further examination is needed, whether it is hypertension, and what
degree of hypertension it is. The entire process allows no ambiguity;
conclusions must be clear and precise.
You may wonder, how do doctors balance between ambiguity and precision
when making judgments?
As Laozi said, "Being and non-being produce each other; difficult and
easy complement each other." Ambiguity and precision are a unity of
opposites. In this lesson, I will break down the doctor's diagnostic
thinking model for hypertension.
This model consists of three steps: logical reasoning, clear evidence,
and risk assessment.
Step 1: Logical Reasoning
This means making a preliminary judgment about the probability of
hypertension based on bits of information and targeted inquiries.
This reasoning process can be summarized as points, lines, and planes.
A point is a clue—anything related to hypertension counts. It could be
an occasional high blood pressure reading, certain symptoms like
recurrent headaches, dizziness, palpitations, or a major illness such
as myocardial infarction or stroke.
Once we spot this clue, we pursue all related points and try to connect
them into a line of blood pressure development.
These clues include: high blood lipids, diabetes, family history of
hypertension, smoking, heavy drinking, staying up late, salty diet,
high work stress, etc. Each is a risk factor; the more you have, the
higher the probability of hypertension.
When the patient's blood pressure development line becomes clear, we
compare it to the population average. These two lines form a plane—
If the two lines match, the pattern fits, and we consider the person's
blood pressure close to steady state, with a low probability of
hypertension. If not, the likelihood is higher, and more precise tests
are warranted.
Step 2: Clear Evidence
As you see, in the initial diagnosis, doctors act like
detectives—finding clues, reasoning logically. But reasoning alone is
not enough. As the saying goes, "Extraordinary claims require
extraordinary evidence." To confirm hypertension, we need solid
evidence.
Specifically, there are three standard blood pressure measurements:
office blood pressure, home monitoring, and 24-hour ambulatory blood
pressure monitoring.
Office Blood Pressure
First is office blood pressure, measured in the hospital. But a single
measurement is not enough. Over four weeks, measure blood pressure two
to three times at the hospital; only if each reading reaches 140/90
mmHg can hypertension be diagnosed. Note: "each reading" must reach the
threshold; if any is below, it does not count.
This sounds strict, but even so, the error rate is 10–30%. Facing
doctors, two peculiar situations arise:
One is "white coat hypertension." These people have normal blood
pressure outside the hospital, but it rises when seeing a doctor—up to
30% prevalence.
The other is "masked hypertension," the opposite: normal readings in
the hospital, but high blood pressure at other times.
Home Monitoring
Clearly, office measurements are not enough. We also need home
monitoring, which is more reflective of real-life risk and more
accurate than office readings.
How to measure at home?
My advice: every household should have an electronic blood pressure
monitor, certified by the Chinese FDA, upper-arm type.
Certification is crucial. Some wearable devices, like fitness bands,
can measure blood pressure but are not medical devices—fine for fun,
not for diagnosis.
Upper-arm type is recommended; wrist monitors are not ideal, as global
standards use elbow measurements for comparison.
For accuracy, note the following:
- No smoking, alcohol, or coffee 30 minutes before measurement; rest
quietly for 3–5 minutes.
- Measure in a quiet room, seated with back support, feet flat on the
floor, no leg crossing.
- Cuff should be above the elbow, not on the elbow; snug enough for one
finger under the cuff; elbow, heart, and monitor at the same level.
- Do not rely on a single measurement. Measure twice each morning and
evening for seven days, one minute apart. Discard the first day's
results; average the rest for your blood pressure.
If ≥135/85 mmHg, according to the 2020 Global Hypertension Guidelines,
hypertension can be diagnosed.
24-Hour Ambulatory Blood Pressure Monitoring
Home monitoring has many caveats; errors can occur. The solution:
24-hour ambulatory blood pressure monitoring—the most accurate,
globally recognized method.
This involves wearing a portable monitor for 24 hours, measuring every
15–30 minutes during normal activities. The next day, return the device
and receive a dynamic blood pressure report.
Three key values: 1) 24-hour average blood pressure—>130/80 mmHg
indicates hypertension; 2) daytime average—>135/85 mmHg; 3) nighttime
average—>120/70 mmHg. Meeting any one criterion confirms hypertension.
Accurate measurement enables precise diagnosis, grading, and treatment.
"Details determine success," and strict quality control ensures correct
judgment.
All three methods aim to capture blood pressure trends, not single
readings—because hypertension is fundamentally an unstable state, not a
fixed threshold.
Step 3: Risk Assessment
Based on measurements, hypertension can be graded. Grading determines
severity—grade 1, grade 2, etc.—to predict risk and guide treatment,
much like sentencing based on evidence.
According to the "Chinese 2018 Hypertension Prevention and Treatment
Guidelines," hypertension is divided into five grades, based on office
blood pressure:
- <120/80 mmHg: "Normal blood pressure"
- ≥120/80 mmHg and <140/90 mmHg: "High-normal"—best period for
prevention
- ≥140/90 mmHg and <160/100 mmHg: Grade 1 hypertension—golden period
for reversal
- ≥160/100 mmHg and <180/110 mmHg: Grade 2 hypertension
- ≥180/110 mmHg: Grade 3 hypertension
If systolic and diastolic pressures fall into different grades, use the
higher grade. For example, 150/105 mmHg is grade 2 hypertension.
Grading, combined with other risk factors, organ damage, and
comorbidities, allows comprehensive assessment of cardiovascular risk:
low, medium, high, or very high.
The assessment table is attached at the end. All subsequent
treatments—medication or otherwise—depend on this risk level, so the
table is very important; I recommend downloading and printing it.
Preview of the Next Lesson
Next, we’ll discuss blood pressure management throughout the life
cycle, starting with how to avoid hypertension.
I am Jessica. See you next time.
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