CC Nurse | Respiratory Assessment

• Gas Exchange: Primary goal: O2/CO2 exchange across alveolar-capillary membrane12.
• Anatomy: Upper tract warms/humidifies/filters air; epiglottis covers larynx to prevent aspiration3. Carina is highly sensitive, triggering vigorous cough on stimulation3.
• Aspiration: Right mainstem bronchus is shorter, wider, straighter than left; aspiration is far more common in right lung4.
• Dead Space: Normal tidal volume ($V_T$) is ~500 mL (~150 mL is anatomical dead space [$V_D$] without gas exchange)2.
• Alveoli & Surfactant: 300M+ alveoli connect via pores of Kohn2. Surfactant lowers surface tension, preventing collapse (atelectasis)2.
• Pleural Biology: Visceral pleura lacks pain fibers5; parietal pleura has pain fibers, causing sharp pleuritic pain during inflammation5.
• Ventilation: Inspiration is active (diaphragm contracts, drawing air in)56; expiration is passive via elastic recoil6.
• Compliance & Resistance: Compliance decreases in edema, ARDS, fibrosis, and increases in COPD6. Resistance is driven by airway diameter7.
• Control: Central chemoreceptors (medulla) respond to CSF pH/$H^+$ changes; peripheral receptors respond to low $PaO_2$, low pH, high $PaCO_2$7. COPD may rely on hypoxic drive7.
• Defense: Alveolar macrophages provide primary defense below bronchioles8. Smoking impairs their phagocytic activity8.

Gerontologic & Assessment Key Concepts

• Aging: Stiffened chest walls, decreased muscle strength, and fewer elastic alveoli cause early airway closure in lung bases (lower $PaO_2$)9. Decreased cilia, cough force, and pharyngeal sensation raise infection/aspiration risks9.
• Hypoxia Findings: Early signs: restlessness, apprehension, tachycardia, mild hypertension, tachypnea10. Late signs: cyanosis, coma, hypotension, accessory muscle use10.
• Physical Exam:
  • Fremitus: High in pneumonia/edema (dense); low in COPD, pleural effusion1112.
  • Percussion: Normal resonance11; hyperresonance in air trapping (COPD, pneumothorax)1112; dullness in fluid/consolidation (effusion, pneumonia)1112.
  • Sounds: Bronchial (trachea, 2:3 ratio), Bronchovesicular (scapulae, 1:1), Vesicular (periphery, 3:1)13.

High-Yield Diagnostics & Procedures

• Oximetry: Arterial $SpO_2$ (normal >95%) is inaccurate if <70%, or with cold, hypoperfusion, vasopressors14. Venous $SvO_2/ScvO_2$ (normal 60-80%) tracks $O_2$ supply/demand balance1415. Low values show anemia, low cardiac output, high demand1516. High values (sepsis) signal poor tissue extraction1516.
• Procedures:
  • Bronchoscopy: Signed consent, NPO 6-12h before, keep NPO after until gag reflex returns17.
  • Thoracentesis: Done sitting upright leaning on table18; post-procedure chest X-ray checks for pneumothorax1718.