Respiratory Pathophysiology 

S&S of Pulmonary Disease

• Dyspnea: subjective sensation of uncomfortable breathing (SOB & difficulty breathing)
• Orthopnea: dyspnea while laying down
• Paroxysmal nocturnal dsypnea (PND): violent attacks of severe SOB and coughing; only occurs at night and awakes person from sleep
    * The emotional is more severe than the physical for patients
• Finger clubbing → hypoxic epithelial tissue compensates and grows new blood vessels
    * 160º → normal finger and nail bed
    * 180º → early clubbing
    * \
      > 180º → moderate & advanced clubbing
• Coughing
    * Acute cough → less than 14 days
    * Chronic cough → more than 14 days
• Sputum: should generally be odorless (if putrid = tissue death)
    * ==Productive cough:== coughing up sputum
    * ==Non-productive cough:== no sputum
    * Bloody: hemoptysis
      * @@Blood-streaked sputum:@@ inflammation, lung cancer in lower airway
      * @@Pink sputum:@@ sputum evenly mixed with blood from alveoli and or small peripheral bronchi → CHF (pulmonary edema)
      * @@Massive blood:@@ TB, tumor, abscess, pulmonary embolism
    * $Yellow(ish):$ purulent/pus = bacterial pneumonia
    * %%Green/greenish:%% longstanding lung infection = chronic bronchitis
    * ==Rust colored:== TB, pneumococcal pneumonia

Breathing Patterns

• Tachy=fast/rapid
• Brady=slow
• Hypoventilation → Hypercapnia (deep breath)
• Hyperventilation → Hypocapnia (shallow depth)
• Eupnea: normal breathing rate and pattern
• Tachypnea: increased respiratory rate, caused by: fever, anxiety, shock
• Bradypnea: Decreased respiratory rate, caused by: sleep, drugs, metabolic disorders, head injury, stroke
• Apnea: absence of breathing, caused by: death, head injury, stroke
• Hyperpnea: normal rate, but deep respirations, caused by: emotional stress, diabetic ketoacidosis
• ==Cheyne-Stokes:== gradual increases and decreases in respirations with periods of apnea, caused by: $NEURO$, increasing intracranial pressure, brain stem injury
• Biot’s: rapid deep respirations (gasps) with short pauses between sets, caused by: spinal meningitis, CNS causes, head injury
• ==Kussmaul’s:== tachypnea and hypernea, caused by: renal failure, metabolic acidosis, diabetic ketoacidosis
• Apneustic: prolong inspiratory phase with shortened expiratory phase, caused by: lesion in brain stem

Adventitious Breath Sounds

• Crackles (rales): bronchioectasis, bronchitis, pneumonia, fibrosis, CHF; course vs. fine
    * Discontinuous
• Wheezes: asthma, COPD and airway obstruction
    * Continuous
• Rhonchi: suggests secretions in the large airway
    * Continuous

Pleural Abnormalities

• Pneumothorax → air ends up in thoracic cavity → causes lung collapse
    * %%Spontaneous (PRIMARY) pneumothorax:%% just happens, occurs in thin, tall, white, male, smokers at risk
    * $Secondary pneumothorax:$ caused by obvious lung diseases; people with cancer, cysts, infection, inflammation (always pathogenic causes)
    * @@Traumatic pneumothorax: @@
      * Iatrogenic → hospital caused (bronchoscopy most common cause)
      * Blunt vs. penetrating → stab wounds, GSWs, car crash
    * ==Tension pneumothorax:== complication from primary OR secondary pneumothorax; causes the pressure to shift to non-affected side (can cause tracheal deviation, heart compression), ⬆️ in mortality

Lung Diseases

Restrictive Pulmonary Disorder

• Lungs are restricted from fully expanding; $troubles inhaling$
    * Air has a problem going into the lungs
• Condition: stiffness in the lungs, chest wall, weak muscles, or damaged nerves may cause restriction

Obstructive Pulmonary Disorder

• $Hard to exhale all the air in the lungs$
    * Air had a problem leaving the lungs, trapped in alveoli
• Damage to the lungs or narrowing of the airways → high amounts of air may still linger in the lungs, ⬆️ in CO2 levels

Types of Restrictive Lung Disorders

• Parenchymal:
    * Atelectasis
    * Fluid (edema, pus, blood)
    * ARDS
    * Trauma
    * Autoimmune
    * Chronic infections
    * Occupational
    * Environmental
• Extra-pulmonary
    * Obesity
    * Scoliosis
• Neuromuscular
    * Myasthenia gravis
    * ALS

Types of Obstructive Lung Disorders

• Airway narrowing and obstruction that is worse with expiration
    * Accessory muscles of expiration required
    * Increased work of breathing
• Dyspnea and wheezing most seen with this disorder
• Asthma, COPD (emphysema & chronic bronchitis)

Atelectasis

• RESTRICTIVE
• Loss of lung volume due to the collapse of alveoli

Pathogenesis:

• ^^Absorptions (obstructive)^^ → can develop pneumonia → the reason why patients have to get up and walk after surgery → spirometer also reduces risk
• %%Non-obstructive →%% loss of contact between visceral and parietal pleura; surfectant impairment (adhesive)
    * Compression (fluid, air, mass, bed-ridden)
    * Contraction (smokers, fibrosis, infection, pneumoconiosis)

ARDS

• RESTRICTIVE
• Acute respiratory distress syndrome
• ==Most severe form of acute lung injury==; ==highest mortality rate== (impacts both alveoli & blood vessels/ alveolocapillary membrane)

Development

Acute lung injury (to blood vessels) → endothelial cell damage → activation of neutrophils/macrophages/platelets → release of inflammatory cytokines → increase aveolocapillary permeability w/edema → V/Q mismatch (shunt) & hypoxemia → ==acute respiratory failure ==

Acute lung injury (to alveoli)→ epithelial cell damage → type II pneumocyte damage → decreased surfectant → alveoli collapse → atelectasis and decreased lung compliance → decreased tidal volume & hypercapnia (muscles tire out) → ==acute respiratory failure ==

Manifestations

• Dyspnea & hypoxemia (O2 sats drop)
• Pulmonary edema
• Increased work of breathing → hyperventilation and respir. alkalosis
• Bilateral infiltrates on chest x-ray
• Respiratory failure, decreased cardiac output, hypotension, death

Diagnosis & Care

• Have to treat accordingly = supportive care
• Hx of lung injury
• Physical exam (won’t really show)
• Analysis of ABGs
• Radiologic exam

• No exact Tx… only support
    * COVID → give antibiotics
    * Smoke inhalation → O2 treatment
    * Chemical inhalation → no Tx, have the let the chemicals absorb into the body before Tx can even be considered to treat

Asthma

• OBSTRUCTIVE
• Reversible airflow obstruction
• LOCATION: Small bronchi, bronchioles
• Typer I hypersensitivity reaction
• Most common chronic disease in children
• NO KNOWN CAUSE (genetic vs. environmental)

Pathogenesis

1. Allergen or irritant exposure
2. Mast cell degranulation and release of mediators → bind to receptors
3. Mediator effects:

   
   1. Mucus production → mucus plug
   2. Vascular leak → cell edema
   3. Airway smooth muscle constriction → bronchoconstriction
   4. Neutrophil activiation → release of serotonin, histamine, and heparin

• Trifecta of Asthma: a,b,c only
• All have one thing shared: air is trapped in the alveoli and can’t get out (can get air in but not out)

Manifestations

• Cough
• Wheezing
    * Expiratory only = mild & moderate
    * Expiratory & inspiratory = SEVERE
• SOB, tachypnea
• Nasal flaring
• Use of accessory muscles
• Exercise intolerance → seen in adult population (cool weather can cause bronchospasms)

Diagnosis

• Clinical, doesn’t require $ testing
• ABGs
• Pulse Ox.
• Chest radiography
    * ABGs and Pulse Ox. determine severity

Management

• Corticosteroids → decreases inflammatory response (edemas, mucus plugs, etc.)
• Beta agonist: albuterol → inhaled, smooth muscle relaxation
• Anti-cholinergic: ipratropium → relaxes muscle
• Phosphodiesterase enzyme inhibitor: theophylline (xanthine) → vasodilation
• Mast cell stabilizer: cromolyn sodium → for those who go outside and exercise
• Leukotrine receptor antagonist: Zafirulkast → blocks inflammatory response
• Monoclonal antibodies: omalizumab
• Combination drugs → steroids, agonists/cholinergic drugs mixed together

How many attacks = how many drugs the patient will take

Classification of Asthmas

COPD

• OBSTRUCTIVE
• Chronic obstructive pulmonary disease
• Umbrella term for other disease (chronic bronchitis & emphysema)
• Not fully reversible, but can be managed
• %%MOST COMMON CHRONIC LUNG DISEASE IN THE WORLD%%
• Risk Factors:
    * Tobacco smoke → vaping popular in US, smoking still popular in Europe/Asia
    * Air pollution → highly populated cities with smog/pollution
    * Genetics

^^Chronic Bronchitis^^

• ^^BLUE BLOATERS ^^
• Hypersecretion of mucus and chronic productive cough that lasts for at least %%3 consecutive months of the year%% and for at least %%2 consecutive years%%
• LOCATION: Bronchi
• Hx of smoking
• Living in urban areas, “dirty air”
• ==3rd leading cause of death in the US==
• Greater than 40 years old
• ^^Overweight, cyanotic, elevated Hgb’s, peripheral edemas, rhonchi and wheezing ^^
    * Frequent infections, common CHF, large amounts of purulent pus coughed up

==Emphysema==

• ==PINK PUFFERS==
• Abnormal, permanent dilation of gas-exchange airways accompanied by the destruction of alveolar walls (elastic septum) without obvious fibrosis
• LOCATION: Alveoli
• Disease of the air spaces
• Loss of elastic recoil
• @@Barrel chested, pursed lips, older and thin, severe dyspnea, quiet chest @@
    * Little sputum, late CHF
• Caused by smoking or inherited deficit of alpha 1-antitrypsin
    * Trypsin digests elastic fibers, antitrypsin prevents it from digesting the elastic fibers, appears like a history of smoking; ==this deficit is seen in younger patients only== ==; loses the ability to protect elastic fibers==

Diagnosis

• Spirometry
• ERB measured for COPD
    * IRB & ERB = functional vital capacity
• Pulmonary function test = baseline
• ABGs → checks for pH of blood, PO2, PCO2, HCO3-
• Serum chemistries
• Alpha-1-antitrypsin levels → ALWAYS DO THIS (young vs. old patients)
• Sputum evaluation → bacteria → inflammation/infection → antibiotics to treat

Treatment & Management

• ==In truth, some patients just won’t make the changes and won’t care about their health ==
• Improvement of functional status, symptoms, and quality of life
• Preventing recurrences
• NO Tx available to improve lung function, other than lung transplants
• O2 therapy when appropriate
• Smoking cessation may reduce mortality

Pneumonia

• Any infection of the lung tissue (parenchyma); alveoli filled with fluid & pus
• %%Typical pneumonia:%% fever (high, 101.5), cough (productive), rigor (chills); lobar pneumonia & bronchopneumonia
• ==Atypical pneumonia==: fever (low, <100), cough (non-productive); “walking pneumonia (PAP)”

Community Acquired Pneumonia

• Clinical setting = community (walking into hospital/doctor’s office)
• Non-hospitalized or previous ambulatory patient
• Bronchial breath sounds and crackles on auscultation; fever, cough, sputum production, rigors, pleuritic chest pain, dyspnea, tachycardia
• %%TYPICAL%%%%:%%
    * ==S. pneumonia==, H. influenza, Legionella
      * S. pneumonia is most common and most fatal
• ==ATYPICAL: ==
    * Mycoplasma, Chlamydia
      * Virus
        * Respiratory syncytial virus → children
        * Para-influenza → children
        * Influenza A & B → older population
        * Adenovirus → military barracks

Nosocomial Pneumonia

• Gram - rods
• MRSA
• Alcoholics, bed-ridden, stroke, unconscious
• ==Ventilators = highest chance to develop nosocomial infections (pseudomonas aerugionsa) ==
• Asplenic patients
• Chronic
• Necrotizing
• Immunocompromised (HIV, cancer therapy)

Pulmonary Tuberculosis

• Caused by an acid-fast bacillus, mycobacterium tuberculosis (AIRBORNE)
    * Living in crowded conditions
    * Immunodeficiency
    * Malnutrition & alcoholism → seen in the homeless
    * War
    * Chronic disease
• Pathogenesis → tubercule/granuloma formation → caseous necrosis

Clinical Presentation (for chronic infectious disease)

• Cough w/blood
• Weight loss/anorexia
• Fever (low grade, 100-100.5)
• ==NIGHT SWEATS = distinctive sign of active infection ==
• Hemoptysis
• Chest pain
• Fatigue

Active Infections

• Acid-fast sputum smear test (when + = active TB)
    * Early morning, 3 consecutive days of collecting
• Chest radiography → shows active TB
• Drug susceptibility testing
• Tx depends

Diagnostics

• Blood test: IGRAs
    * $
    * Single patient visit
    * CDC recommended
• Tuberculin skin test: TST
    * Recorded 2-3 days after 1st administration

• HIV serology test → HIV & TB go hand in hand, so always good to check if HIV is +