Blood Pressão Unidades
Understanding mmHg Measurements
Learn o BasicsBlood pressure readings like "120/80" são given in millimeters of mercury (mmHg)—a unidade dating back to early mercury barometers. Understanding o que estes numbers mean, por que este unidade persists in medicine, e como to interpret readings é essential for monitoring cardiovascular health.
Por que Millimeters of Mercury?
Historical Origin
O primeiro blood pressure medições in o 1700s usado mercury manometers—U-shaped tubes of mercury onde blood pressure pushed o mercury column up. O height in millimeters became o padrão unidade.
Por que It Persists
- Continuity: Decades of medical research uses mmHg
- Precision: Convenient numbers for typical readings (40-200)
- Clinical familiarity: Todos healthcare providers understand mmHg
- International padrão: Usado worldwide in medicine
Converting to outro unidades would require rewriting medical guidelines, retraining clinicians, e replacing todos existing documentation.
Blood Pressão Categories
| Category | Systolic (mmHg) | Diastolic (mmHg) | |
|---|---|---|---|
| Normal | Menos than 120 | e | Menos than 80 |
| Elevated | 120-129 | e | Menos than 80 |
| High BP Stage 1 | 130-139 | ou | 80-89 |
| High BP Stage 2 | 140+ | ou | 90+ |
| Hypertensive Crisis | 180+ | e/ou | 120+ |
Based on American Heart Association guidelines (2017).
Converting mmHg to Outro Unidades
While medicine uses mmHg exclusively, you may need conversions for scientific ou engenharia contexts:
| BP Reading | mmHg | kPa | PSI | bar |
|---|---|---|---|---|
| Normal | 120/80 | 16.0/10.7 | 2.32/1.55 | 0.160/0.107 |
| High Stage 1 | 135/85 | 18.0/11.3 | 2.61/1.64 | 0.180/0.113 |
| High Stage 2 | 150/95 | 20.0/12.7 | 2.90/1.84 | 0.200/0.127 |
Conversão Formulas
- mmHg to kPa: Multiply by 0.1333
- mmHg to PSI: Multiply by 0.01934
- mmHg to bar: Multiply by 0.001333
Understanding o Numbers
Systolic Pressão (Top Number)
O pressure in arteries quando your heart beats e pumps blood. It's o higher number because este é o maximum pressure in your circulatory sistema.
Diastolic Pressão (Bottom Number)
O pressure in arteries entre heartbeats, quando o heart rests e refills com blood. It's lower because este é o minimum pressure.
Pulse Pressão
O difference entre systolic e diastolic (normally 40-60 mmHg). A muito wide ou narrow pulse pressure can indicate health issues.
Factors Affecting Blood Pressão
| Fator | Effect on BP |
|---|---|
| Exercise (immediate) | Increases temporarily |
| Exercise (long-term) | Decreases |
| Sodium intake | Increases |
| Stress | Increases |
| Caffeine | Increases temporarily |
| Alcohol (excess) | Increases |
| Age | Typically increases |
| Body position | Varies by position |
| Tempo of day | Lower at night, higher in morning |
Home Blood Pressão Monitors
Modern digital monitors display readings in mmHg, o mesmo unidade usado clinically. Key features to look for:
- Validated accuracy: Look for clinically validated devices
- Proper cuff size: Too small ou large gives inaccurate readings
- Memory function: Stores readings for tracking
- Averaging feature: Calculates average of multiple readings
Upper arm monitors são generally mais preciso than wrist monitors.
Conclusão
Blood pressure é universally measured in millimeters of mercury (mmHg) due to historical convention e clinical practicality. Normal blood pressure é below 120/80 mmHg. Understanding ambos numbers—systolic (heart beating) e diastolic (heart resting)—helps you monitor cardiovascular health. While you can converter to outro pressure unidades, medical contexts always use mmHg.