Key Takeaways
- The average resting heart rate for healthy adult males aged 18-25 years is 70-73 beats per minute (bpm).
- Athletes in endurance sports have resting heart rates as low as 40-60 bpm due to cardiovascular adaptations.
- Resting heart rate above 90 bpm in adults is associated with a 1.5-fold increased risk of cardiovascular mortality.
- Normal adult systolic blood pressure (SBP) is less than 120 mmHg and diastolic (DBP) less than 80 mmHg.
- Hypertension stage 1 defined as SBP 130-139 mmHg or DBP 80-89 mmHg, affecting 46% US adults.
- Isolated systolic hypertension (ISH) in >60 years: SBP ≥140 mmHg, DBP <90, prevalence 30%.
- Normal core body temperature is 36.5-37.5°C (97.7-99.5°F) orally.
- Hypothermia classified as mild 32-35°C, moderate 28-32°C, severe <28°C.
- Fever threshold 38°C (100.4°F) rectally in adults.
- Normal resting respiratory rate for adults is 12-20 breaths per minute (bpm).
- Tachypnea defined as >20 bpm in adults, >60 bpm neonates.
- Bradypnea <12 bpm adults, associated with opioid overdose.
- Normal SpO2 on room air for healthy adults at sea level is 95-100%.
- Hypoxemia defined as SpO2 <90%, severe <85% requiring oxygen.
- COPD patients target SpO2 88-92% to avoid hypercapnic failure.
Vital signs reveal critical health insights across different ages and conditions.
Blood Pressure
- Normal adult systolic blood pressure (SBP) is less than 120 mmHg and diastolic (DBP) less than 80 mmHg.
- Hypertension stage 1 defined as SBP 130-139 mmHg or DBP 80-89 mmHg, affecting 46% US adults.
- Isolated systolic hypertension (ISH) in >60 years: SBP ≥140 mmHg, DBP <90, prevalence 30%.
- Mean arterial pressure (MAP) target 65-110 mmHg in ICU critically ill patients.
- Pulse pressure (systolic minus diastolic) >60 mmHg predicts CVD events (RR 1.6).
- White coat hypertension: office BP ≥140/90 but ambulatory <130/80, 15-30% hypertensives.
- Orthostatic hypotension: SBP drop ≥20 mmHg or DBP ≥10 mmHg within 3 min standing.
- Pregnancy BP norms: <120/80 mmHg pre-pregnancy, preeclampsia >140/90 after 20 weeks.
- Ambulatory BP monitoring daytime average: 135/85 mmHg threshold for hypertension.
- Salt intake >5g/day raises SBP by 5-10 mmHg in salt-sensitive individuals (40% population).
- Alcohol >3 drinks/day increases SBP by 4-7 mmHg chronically.
- Obesity (BMI>30) elevates SBP by 10-15 mmHg vs normal weight.
- ACE inhibitors lower SBP/DBP by 10-15/6-10 mmHg in hypertensives.
- BP variability (SD >12 mmHg SBP) doubles stroke risk independently.
- Children BP percentiles: 95th for hypertension, e.g., 10yo boy SBP 114 mmHg.
- Masked hypertension: normal office BP but ambulatory elevated, 10-15% prevalence.
- SBP <90 mmHg in shock requires vasopressors to target >65 MAP.
- Elderly >80yo hypertension target <150/90 mmHg per HYVET trial.
- Diabetes BP target <130/80 mmHg reduces nephropathy risk by 33%.
- Smoking acutely raises SBP 5-10 mmHg for 15-30 min post-cigarette.
- Exercise lowers resting SBP by 5-8 mmHg sustained with 150 min/week.
- CKD stage 3-5 BP target <140/90 mmHg, but <130/80 if proteinuria >1g/day.
- Nocturnal BP dipping 10-20% normal; non-dippers (0-10%) have 2x CVD risk.
Blood Pressure Interpretation
Body Temperature
- Normal core body temperature is 36.5-37.5°C (97.7-99.5°F) orally.
- Hypothermia classified as mild 32-35°C, moderate 28-32°C, severe <28°C.
- Fever threshold 38°C (100.4°F) rectally in adults.
- Hyperpyrexia >41.5°C (106.7°F) risks organ failure.
- Diurnal temperature variation 0.5-1°C, peaking late afternoon.
- Infants normal axillary temp 36.6-38°C, higher risk of febrile seizures at >39°C.
- Menopause hot flashes raise core temp by 0.5-1°C transiently.
- Aspirin reduces fever by 1-2°C within 1-2 hours in children >2yo.
- Hypothyroid patients have baseline temp 0.3-0.5°C below normal.
- Heat stroke core temp >40°C with CNS dysfunction.
- Tympanic temperature overestimates oral by 0.5°C, underestimates rectal by 0.5°C.
- Elderly have reduced fever response, peak 1°C lower than young adults.
- Ibuprofen lowers temp by 1.5°C max in 3 hours for febrile adults.
- Sepsis fever >38.3°C or hypothermia <36°C, 90% mortality if untreated.
- Pregnancy raises baseline temp 0.3-0.5°C due to progesterone.
- Athletes post-exercise temp peaks at 39-40°C, cools 0.1°C/min.
- Alcohol intoxication lowers core temp by 0.5-1°C via vasodilation.
- Malaria causes cyclic fevers 39-41°C every 48 hours in P. falciparum.
- Normal skin temp gradient: core-skin 2-4°C at rest.
- Acetaminophen reduces fever by 0.8-1°C in 2 hours, plateau effect.
- Neuroleptic malignant syndrome temp >38°C with rigidity, CK>1000.
- Pediatric normal rectal temp <38°C; oral unreliable <5yo.
Body Temperature Interpretation
Heart Rate
- The average resting heart rate for healthy adult males aged 18-25 years is 70-73 beats per minute (bpm).
- Athletes in endurance sports have resting heart rates as low as 40-60 bpm due to cardiovascular adaptations.
- Resting heart rate above 90 bpm in adults is associated with a 1.5-fold increased risk of cardiovascular mortality.
- Neonatal heart rate at birth averages 120-160 bpm, decreasing to 100-140 bpm within the first hour.
- In children aged 1-2 years, normal heart rate ranges from 80-130 bpm during rest.
- Post-exercise heart rate recovery (1-minute drop) below 12 bpm indicates higher cardiac risk.
- Women have an average resting heart rate 2-7 bpm higher than men across all age groups.
- Heart rate variability (HRV) standard deviation of NN intervals below 50 ms predicts mortality in heart failure patients.
- Tachycardia threshold for adults is >100 bpm at rest, affecting 10-20% of emergency visits.
- Bradycardia is defined as <60 bpm in adults, with symptomatic rates <50 bpm requiring intervention.
- Average heart rate during moderate aerobic exercise for adults is 50-70% of maximum HR (220-age).
- In elderly adults over 65, resting HR averages 60-80 bpm, with increases linked to frailty.
- Caffeine increases resting heart rate by 5-10 bpm in habitual consumers.
- Sleep heart rate dips 10-20% below daytime average in healthy adults.
- Hyperthyroidism elevates resting HR by 20-30 bpm on average.
- Beta-blockers reduce resting HR by 10-15 bpm in hypertensive patients.
- Maximum heart rate formula for adults: 220 - age, validated in populations up to 80 years.
- Heart rate >120 bpm during sleep indicates potential sleep apnea severity.
- In pregnancy, resting HR increases by 10-20 bpm from first to third trimester.
- Anemia correlates with resting HR elevation of 10 bpm per 2 g/dL hemoglobin drop.
- Resting HR reduction of 10 bpm via exercise lowers CVD risk by 20%.
- Pediatric heart rate norms: 3-12 months 80-140 bpm, 1-5 years 75-120 bpm.
- Dehydration increases HR by 5-10 bpm per 1% body weight loss.
- HRV low frequency/high frequency ratio >2 indicates sympathetic dominance in stress.
- Postural orthostatic tachycardia syndrome (POTS) defined as HR increase >30 bpm upon standing.
- Smoking raises resting HR by 2-5 bpm acutely, chronic by 5-10 bpm.
- Alcohol withdrawal tachycardia peaks at 110-120 bpm on day 2-3.
- Hypothermia (<35°C) slows HR by 10-20 bpm per 1°C drop.
- Digitalis toxicity causes ventricular rate 150-200 bpm in AFib patients.
- Normal sinus rhythm HR in infants 0-3 months: 100-180 bpm.
- Optimal resting HR for longevity in men is 50-70 bpm per Framingham study.
Heart Rate Interpretation
Oxygen Saturation
- Normal SpO2 on room air for healthy adults at sea level is 95-100%.
- Hypoxemia defined as SpO2 <90%, severe <85% requiring oxygen.
- COPD patients target SpO2 88-92% to avoid hypercapnic failure.
- Neonates SpO2 92-95% post-ductal after 10 min life, preterms lower.
- PaO2/FiO2 ratio <300 mild ARDS, <200 moderate, <100 severe.
- Anemic patients SpO2 normal but oxygen content low if Hb<7g/dL.
- High altitude 5000m SpO2 averages 85-90% acclimatized.
- Supplemental O2 2L/min nasal cannula raises SpO2 5-10% in hypoxemic.
- Sleep SpO2 nadir <90% in 5% dips defines moderate OSA.
- Sepsis SpO2 <92% on RA predicts mortality OR 2.9.
- Pneumonia CURB-65 RR and SpO2<90% add points for severity.
- Post-op SpO2 <90% for >10% time increases complications 2-fold.
- Cyanotic heart disease SpO2 75-85% chronic stable.
- Methemoglobinemia SpO2 85% plateau unresponsive to O2.
- Pregnancy SpO2 unchanged 96-99%, but PaO2 rises 10 mmHg.
- Elderly SpO2 <94% prompts evaluation for COPD/CHF.
- Pulse oximeter accuracy ±2% in 85-100% range, poor <70%.
- Obesity hypoventilation SpO2 <88% awake chronic.
- Exercise desaturation SpO2 drop >4% predicts mortality in IPF.
Oxygen Saturation Interpretation
Respiratory Rate
- Normal resting respiratory rate for adults is 12-20 breaths per minute (bpm).
- Tachypnea defined as >20 bpm in adults, >60 bpm neonates.
- Bradypnea <12 bpm adults, associated with opioid overdose.
- Infants 1-12 months: 30-60 bpm normal at rest.
- Children 1-5 years: 20-30 bpm, 6-12 years 18-25 bpm.
- COPD exacerbation RR >25 bpm predicts ICU admission (OR 2.5).
- RR >30 bpm in pneumonia increases 30-day mortality by 20%.
- Sleep RR averages 12-16 bpm, drops 2-4 bpm in deep sleep.
- Pregnancy increases RR by 1-2 bpm due to progesterone.
- Exercise peak RR 35-45 bpm in untrained adults, up to 60 in athletes.
- Kussmaul respirations >20 deep breaths/min in DKA metabolic acidosis.
- Cheyne-Stokes RR cycles 30s-2min with crescendo-decrescendo pattern in CHF.
- Asthmatic RR >22 bpm at ED triage sensitivity 91% for admission.
- Elderly RR >24 bpm mortality risk RR 1.78 in community-acquired pneumonia.
- Hypercapnia RR <12 bpm common in CO2 retainers COPD.
- Post-op RR >25 bpm predicts pulmonary complications (OR 4.4).
- Sepsis qSOFA RR ≥22 bpm scores 1 point, sensitivity 74%.
- Anxious hyperventilation RR 20-40 bpm with carpopedal spasm.
- Altitude 3000m increases RR by 4-6 bpm chronically.
- Morphine 10mg IV reduces RR by 4-6 bpm in 30 min.
Respiratory Rate Interpretation
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