Low blood pressure

Disease Description (Causes and Symptoms)

• Definition: In general, systolic blood pressure < 90 mmHg and diastolic blood pressure < 60 mmHg are considered hypotension, but the need for treatment and clinical significance vary depending on the patient's condition (age, underlying diseases, and symptoms).
• Main types and pathophysiology:
  • Hypovolemic: Decreased blood volume due to bleeding, severe vomiting·diarrhea, extensive burns, etc. → Reduced tissue and cerebral perfusion.
  • Cardiogenic: Decreased cardiac output due to acute myocardial infarction, cardiac tamponade, cardiac dysfunction, etc.
  • Septic: Peripheral vasodilation and microcirculatory dysfunction caused by systemic infection.
  • Neurally mediated (vasovagal, orthostatic·neuropathic): Failure of vascular and heart-rate compensation due to autonomic nervous system dysfunction.
  • Drug-induced: Antihypertensive drugs, antianginal drugs, some Parkinson’s medications, antidepressants, α-blockers, etc.
  • Postprandial: Relative hypotension caused by increased blood-flow distribution to the intestines after meals (mainly in older adults).
• Main symptoms: Dizziness (especially when standing), fainting (prodromal symptoms of syncope), pallor·cold sweats, blurred vision, fatigue, shortness of breath, nausea, and reduced concentration. Some people may have no symptoms.

Treatment Methods

• Initial management (emergency situations):
  • Safe positioning (lie down and elevate the legs), and check the airway, breathing, and circulation.
  • In cases of severe hypotension, establish intravenous access, administer fluids (crystalloids), and provide blood transfusion if necessary (for massive bleeding).
  • If the cause of shock is infection, immediately provide appropriate antimicrobial therapy and management according to sepsis guidelines (vasopressors such as norepinephrine, etc.) as determined by the attending physician.
  • Cardiogenic causes (myocardial infarction, cardiac tamponade, etc.) require relevant treatment (coronary intervention, pericardiocentesis/drainage, etc.).
• Treatment according to the cause:
  • Bleeding: Embolization or surgery to control the bleeding source and blood transfusion.
  • Drug-induced: Discontinue or adjust the medications causing hypotension.
  • Vasovagal syncope: Avoidance of triggers and education; medication (e.g., midodrine) may be considered for recurrence.
  • Orthostatic·neurogenic hypotension: Fluid and salt replacement, compression stockings (30 mmHg recommended), fludrocortisone (in some patients), midodrine or droxidopa (used for neurogenic hypotension), increased water intake, and autonomic rehabilitation methods.
  • Postprandial hypotension: Small, high-protein, low-carbohydrate meals and resting after meals.
• Lifestyle management and prevention:
  • Stand up slowly, consume sufficient fluids and salt, avoid excessive alcohol and hot baths, and exercise caution when taking diuretics or blood pressure medications.
• Precautions: Specific medication choices, procedures, fluid volumes, and use of vasopressors are determined by the physician according to the patient's condition. Follow the prescription and instructions.

Checklist Before an Outpatient Visit (Including Items to Bring, Information to Provide, and Example Questions)

• Items/materials:
  • A list of all medications currently being taken (prescription drugs·OTC drugs·herbal medicines·supplements)
  • Records of recently measured blood pressure and pulse (including measurements while seated and standing, and, if possible, the time and activity)
  • Recent blood tests·electrocardiograms·echocardiograms·hospital records (if available)
  • Notes on the circumstances of any fainting or dizziness (position, food intake, time of day, duration, and accompanying symptoms)
  • Any recent signs of bleeding (black stools, blood in the urine, etc.) or possible dehydration
• Useful information to provide to healthcare professionals at the outpatient visit:
  • When the symptoms began and how they have progressed, and aggravating factors (medications·meals·changes in position, etc.)
  • Underlying diseases (heart disease, diabetes, Parkinson’s disease, endocrine diseases, etc.)
• Example questions before the outpatient visit (questions for the patient to consider in advance):
  • "Could any of the medications I am currently taking cause hypotension?"
  • "What can I safely do temporarily when symptoms occur?"

Examples of General Questions to Ask the Doctor

• What side effects could occur if I take this medication (e.g., midodrine or fludrocortisone)?
• What is the suspected cause of my hypotension (bleeding/heart disease/infection/medications/autonomic nervous system), and what additional tests are needed?
• What is the expected prognosis, and what lifestyle changes must I make?
• What immediate measures should I take to reduce the risk of fainting?

Examples of Condition-Specific Questions

• "To determine whether the antihypertensive medication I am taking (or a prostate medication or Parkinson’s medication) is the main cause of my hypotension, do I need to stop taking it? When and how should I stop it?"
• "Are additional tests, such as a tilt-table test or autonomic function testing, needed to determine whether I have orthostatic hypotension? If needed, which department should I be referred to (cardiology vs. neurology)?"

(Note: Follow the judgment of the attending healthcare professional regarding specific tests, medication choices, and emergency treatment.)