How Are Blood Pressure Disorders Diagnosed?
The diagnosis of hypertension relies on an accurate appraisal of blood pressure.
- Normal blood pressure: Systolic <120 mmHg and diastolic <80 mmHg (<120/<80)
- Elevated blood pressure: Systolic 120 – 129 mmHg while diastolic is still <80 mmHg (120-129/<80)
- Hypertension stage 1: Either systolic 130 – 139 mmHg or diastolic 80 – 89 mmHg
- Hypertension stage 2: Either systolic ≥ 140 mmHg or diastolic ≥ least 90 mmHg
Blood pressure measurement is based on audible changes in the pulse across a brief application of a range of pressures, applied via an inflatable cuff around the arm. The initial inflation creates a pressure high enough to stop arterial flow (a tourniquet effect) and then produces sounds from return of pulses and then to silence again as the pressure is released. Both of these events (return of pulses after the silence and changes in the pulses as turbulence resolves) or, simply, the reappearance of pulses and their disappearance again, are recorded as the two numbers (systolic reading and diastolic reading) of the blood pressure.
There are many errors that can invalidate a blood pressure reading, such as crossing of legs, arm position, animated conversation, improper cuff size, and breathing movements. Also, nervousness can result in “white coat hypertension,” which can be misleading.
Correcting for these inaccuracies uses two out-of-office basic strategies:
- Home monitoring: In which a patient can perform blood pressure measurements as many times and as frequently as is convenient.
- Ambulatory monitoring: The standard for out-of-office BP evaluation, in which a recorder works wirelessly with an arm cuff over hours to days to increase the data to improve accuracy of the average blood pressure over time.
Diagnosis also involves testing and appraisal of the co-morbidities associated with hypertension:
- Blood work: A complete metabolic profile (including serum calcium and creatinine, fasting glucose), complete blood count, thyroid hormone level, and kidney and liver function testing, including liver enzymes and estimation of a glomerular filtration rate, respectively.
- Electrocardiogram (ECG): An ECG can identify structural and rhythmic abnormalies.
- Echocardiogram: Ultrasound can evaluate the heart chambers (e.g., ventricular enlargement) and the flow of blood through them, as well as judge the competency of the valves which may play a part in hypertension.
- Appraisal of lifestyle: To identify high-risk stressors that could benefit from counseling and stress-reduction strategies.