Respiratory System Review

Fever

Approaching a patient with fever:

1. Is there truly a fever?

2. Fever classification:

By duration:

Acute fever: Less than 1 week

Prolonged fever: More than 1 week

3. Causes of fever:

4. Fever progression:

5. Complications of fever:

Definition of fever:

Normal body temperature: 36.8 ± 0.4 degrees Celsius

Daytime fever: > 37.2 degrees Celsius

Nighttime fever: > 37.7 degrees Celsius

Diagnostic workup for fever:

Suspicion of infection:

Suggestive of infection, inflammation: CBC, ESR, CRP, procalcitonin

Locating infection, inflammation: Imaging studies (depending on suspected location), urinalysis, CSF examination,…

Finding the causative agent: blood culture, culture of body fluids, sputum smear for AFB, blood smear for malaria parasites, stool examination,…

Endogenous fever-inducing agents:

Interleukin – 1 (IL – 1)

Interleukin – 6 (IL – 6)

Interferon

Endogenous fever-inducing agents that stimulate the hypothalamus to secrete:

Prostaglandin E2

Substance that alters the set point of the hypothalamus:

cAMP

Fever classification by progression:

Continuous fever: Temperature fluctuations not exceeding 1 degree Celsius

Intermittent fever: Temperature fluctuations > 1 degree Celsius

Physiological effects of fever:

An increase of 1 degree Celsius increases respiratory rate by 2-3 breaths/minute

An increase of 1 degree Celsius increases heart rate by 10-15 beats/minute

Hemoptysis

Approaching a patient with hemoptysis:

1. Is there truly hemoptysis?

2. Blood volume:

Large volume: > 100 mL/24h or > 50 mL in a single coughing episode

3. Progression:

4. Complications:

5. Location:

Causes of hemoptysis:

Respiratory:

Airways (pharyngitis, bronchiectasis, pulmonary hemorrhage)

Lung parenchyma (lung abscess, tumors, fungal infection, pulmonary tuberculosis, pneumonia)

Pulmonary vessels (pulmonary embolism)

Cardiovascular: mitral valve stenosis, arterial abnormalities, arteriovenous malformations

Other: autoimmune diseases

Complications of hemoptysis:

Respiratory failure

Hypovolemic shock

Acute kidney injury

Diagnostic workup for hemoptysis:

1. Presence of hemoptysis: (examine sputum)

2. Volume: CBC (check Hct beforehand if acute)

3. Progression: (examine sputum), monitor Hct

4. Complications: monitor Hct, renal function tests, PT/INR

5. Location: Chest X-ray, bronchoscopy, CT-scans (if initial HAH tests are inconclusive), echocardiography

Causative agents: AFB in sputum, D-dimer, ANA antibody test

Asthma and COPD

Characteristics of asthma:

1. Young age

2. Symptoms: cough, wheezing, dyspnea, chest tightness (variable with time, space, and triggers)

3. Impact: responsive to bronchodilators

4. History: family history of asthma or atopy

Characteristics of COPD:

1. Usually > 40 years old

2. Symptoms: productive cough (morning), progressive dyspnea, continuous dyspnea

3. Impact: usually not responsive to bronchodilators, barrel chest,…

4. History: smoking

Steps in diagnosing asthma & COPD:

Acute asthma attack: severity, complications, precipitating factors, control

COPD exacerbation: severity, complications, precipitating factors, GOLD, group

Severity of asthma:

Mild: dyspnea on exertion, lying down, able to speak in complete sentences, normal pulse, no paradoxical pulse

Moderate: dyspnea when talking, when sitting, able to speak in short phrases, wheezing, pulse > 100 bpm, possible paradoxical pulse

Severe: dyspnea at rest, only able to speak one word at a time, respiratory rate > 30 breaths/minute, pulse > 120 bpm, paradoxical pulse

Severity of COPD:

Mild: 1/3 of symptoms, < 4 exacerbations/year

Moderate: 2/3 of symptoms, < 4 exacerbations/year

Severe: all 3 symptoms, > 4 exacerbations/year, age > 65

Assessment of COPD groups:

Groups A, B: 1 exacerbation/year + resolves with medication

Groups C, D: > 1 exacerbation/year + resolves with medication or has 1 exacerbation requiring hospitalization

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Respiratory System Review