Chapter 13

Concept Overview

Gas Exchange represents processes that facilitate and impair the transport of oxygen to tissues and carbon dioxide from tissues. It is interrelated with perfusion, intracranial regulation, metabolism, mobility, tissue integrity, sleep, and nutrition.

• Clinical Case Example: John Armstrong

  • $59$-year-old male, smoked a pack of cigarettes daily for $41$ years.

  • COPD pathology: Obstructed bronchi increase breathing effort; destruction of alveoli impairs diffusion and leads to air trapping.

  • Findings: Hypoxemia, dyspnea ($shortness of breath$), activity intolerance, weight loss/malnutrition, and orthopnea (needs $3$ pillows or sleeps in a recliner).

Anatomy and Physiology

• Purpose: Supply oxygen to cells and remove carbon dioxide through ventilation and diffusion.

• Ventilation: Moving gases in and out of the lungs (inspiration and expiration).

• Diffusion: Movement of gases from higher to lower concentration across the alveolar-capillary membrane.

• Transportation: The cardiovascular system transports gases between alveoli and cells via erythrocytes.

Internal Thorax

• Mediastinum: Middle of the chest; contains heart, aorta arch, superior vena cava, lower esophagus, and trachea.

• Pleural Cavities: Contain the lungs; lined by parietal pleura (chest wall/diaphragm) and visceral pleura (lungs).

• Lung Lobes: Right lung has $3$ lobes; Left lung has $2$ lobes.

• Extension: Apex extends $1.5$ in ($4$ cm) above the first rib; base expands to $T12$ during deep inspiration and rises to $T9$ on expiration.

External Thorax

• Thoracic Cage: $11$ thoracic vertebrae, $12$ pairs of ribs, and the sternum.

  • Ribs $1-7$: Connect to sternum via costal cartilages.

  • Ribs $8-10$: Connect to superior ribs.

  • Ribs $11-12$: Floating ribs.

• Sternum Components: Manubrium, body, and xiphoid process ($17$ cm long).

• Intercostal Space (ICS): Named after the rib above it.

Topographic Markers

• Anterior: Suprasternal notch, Angle of Louis (manubriosternal junction), Midsternal line, Costal angle ($\le 90^{\circ}$), Clavicles, Midclavicular lines.

• Lateral: Anterior axillary lines, Posterior axillary lines, Midaxillary lines.

• Posterior: Vertebra prominens ($C7$), Vertebral line, Scapular lines.

Mechanics of Breathing

• Primary Muscles: Diaphragm and intercostal muscles.

  • Inspiration: Diaphragm contracts/descends, intercostals push chest outward, decreasing intrathoracic pressure (negative pressure).

  • Expiration: Muscle relaxation increases pressure, expelling air.

• Accessory Muscles: Sternocleidomastoid, scalenus, pectoralis minor, etc.

• Upper Airway: Nose, pharynx, larynx, trachea ($10$ cm long). Functions: conductive, protective, warming, filtering, and humidifying.

• Lower Airway: Right/left main-stem bronchi (trachea splits at $T4/T5$), bronchioles, and alveoli.

Health History

• Present Health Status: Assess chronic illnesses (heart/renal disease), allergies, dyspnea during activities, orthopnea, medications (including inhalers and $OTC$/herbal supplements like ginseng), and oxygen use.

• Past Health History: Previous lung problems, injuries, or surgeries.

• Family History: Genetic links for lung disease.

• Personal/Psychosocial History:

  • Tobacco Use: Documented in pack-years ($packs/day \times years$).

  • Infectious Disease Exposure: Screening for $TB$, influenza, or $COVID-19$.

  • Home Environment: Air pollution, allergens (pets, mold, dust mites), hazards (lead, carbon monoxide).

  • Occupational Environment: Exposure to chemicals, dust, asbestos, or vapors.

  • Travel History: Exposure to uncommon diseases (e.g., histoplasmosis, $SARS$).

Problem-Based History (OLD CARTS)

Cough

• Acute: $< 3$ weeks (infections, asthma, embolism).

• Chronic: $> 8$ weeks ($GERD$, $ACE$ inhibitors like captopril).

• Sputum Characteristics:

  • White/Clear: Colds, viral infections.

  • Yellow/Green: Bacterial infections.

  • Black: Smoke/coal dust.

  • Rust: $TB$, pneumococcal pneumonia.

  • Pink/Frothy: Pulmonary edema.

  • Hemoptysis: Blood in sputum.

Shortness of Breath (Dyspnea)

• Dyspnea on Exertion (DOE): Occurs during activity.

• Orthopnea: Difficulty breathing when lying flat.

• Paroxysmal Nocturnal Dyspnea: Awakening at night with suffocation feeling.

• Documentation: Record "word dyspnea" (e.g., "three-word dyspnea" if the patient breathes after every $3$ words).

Chest Pain with Breathing

• Pleuritic Chest Pain: Sharp, stabbing pain during inspiration.

• Splinting: Patient reduces movement on the affected side to minimize pain.

Physical Examination

Routine Techniques

1. Inspect Appearance/Posture: Observe for respiratory distress (nasal flaring, retractions, use of accessory muscles).

   • Tripod Position: Leaning forward, suggests $COPD$/asthma.

   • Pursed-lip Breathing: Slows exhalation in $COPD$.

2. Count Respirations: Normal rate $12-20$ breaths/min (eupnea).

   • Men: Abdominal breathing; Women: Thoracic breathing.

3. Measure Oxygen Saturation: Normal $SaO_2$ is $95\%-100\%$. $< 90\%$ is abnormal.

4. Inspect Skin/Nails: Check for cyanosis, pallor, or clubbing ($chronic hypoxia$).

5. Inspect Thorax: Check for barrel chest ($1:1$ AP to lateral ratio), scoliosis, or other deformities.

6. Auscultation:

   • Vesicular: Low pitch, soft; heard over peripheral lung fields.

   • Bronchovesicular: Moderate pitch; heard over main bronchi.

   • Bronchial: High pitch, loud; heard over trachea.

   • Adventitious Sounds: Crackles (fluid), Wheezes (narrowed airways), Rhonchi (obstruction/mucus), Pleural friction rub (inflammation).

Special Circumstances

• Palpate for Expansion: Thumbs at $T9/T10$; should move apart symmetrically.

• Vocal (Tactile) Fremitus: Palpable vibrations while saying "ninety-nine." Increased in consolidation (pneumonia); decreased in obstruction.

• Tracheal Position: Should be midline and movable.

• Percussion: Normal tone is resonant.

  • Hyperresonance: Overinflation (emphysema).

  • Dullness: Consolidation (pneumonia, effusion, atelectasis).

• Diaphragmatic Excursion: Normal is $3-5$ cm ($7-8$ cm in athletes).

Common Respiratory Conditions

• Acute Bronchitis: Mucous membrane inflammation; rhonchi and wheezing present.

• Pneumonia: Infection of terminal bronchioles; viral (nonproductive) or bacterial (productive).

• Tuberculosis ($TB$): Infectious bacteria ($Mycobacterium tuberculosis$); night sweats, weight loss, fever.

• Asthma: Hyperreactive airway; bronchoconstriction and audible wheezes.

• Emphysema: Alveolar wall destruction; barrel chest and nail clubbing.

• Chronic Bronchitis: Productive cough for $3$ months over $2$ successive years; cyanosis and clubbing.

• Pneumothorax: Air in pleural space causing lung collapse; absent breath sounds over the affected area.

• Hemothorax: Blood in pleural space.

• Atelectasis: Collapsed alveoli due to pressure or hypoventilation.

• Lung Cancer: Malignant cell growth; persistent cough and hemoptysis.

NCLEX Practice Questions: Gas Exchange and Respiratory Assessment

1. A patient with COPD is observed leaning forward with arms supported on a bedside table. Which term should the nurse use to document this finding?

   • A) Orthopnea

   • B) Tripod position

   • C) Splinting

   • D) PND

   • Answer: B. The tripod position is a compensatory posture where the patient leans forward to enhance the use of accessory muscles, common in $COPD$ and asthma.

2. The nurse is calculating the pack-year history for a patient who smoked $2$ packs per day for $15$ years. What is the correct documentation?

   • A) $15$ pack-years

   • B) $20$ pack-years

   • C) $30$ pack-years

   • D) $45$ pack-years

   • Answer: C. Pack-years are calculated as $packs/day \times years$. ($2 \times 15 = 30$).

3. During percussion of the lungs in a patient with emphysema, which sound does the nurse expect to hear?

   • A) Resonance

   • B) Dullness

   • C) Hyperresonance

   • D) Tympany

   • Answer: C. Hyperresonance is heard over hyperinflated lungs, which is a hallmark of emphysema.

4. Which physical assessment finding is most characteristic of chronic hypoxia?

   • A) Pleuritic chest pain

   • B) Midline trachea

   • C) Nail clubbing

   • D) Productive cough

   • Answer: C. Clubbing of the nails is a sign of long-term oxygen deprivation, often seen in $COPD$ or cystic fibrosis.

5. A nurse is assessing a patient for tactile fremitus. Which condition would cause an increase in palpable vibrations?

   • A) Large airway obstruction

   • B) Pneumothorax

   • C) Pneumonia (consolidation)

   • D) Emphysema

   • Answer: C. Consolidation (solidification of lung tissue) as seen in pneumonia increases the transmission of vibrations.

6. The nurse notes the patient’s trachea is deviated to the left. Which condition should the nurse prioritize?

   • A) Atelectasis

   • B) Pneumothorax

   • C) Chronic Bronchitis

   • D) Acute Bronchitis

   • Answer: B. A deviated trachea is a medical emergency often associated with a tension pneumothorax where air pressure shifts the mediastinum.

7. A patient reports awakening suddenly at night with a feeling of suffocation. How should the nurse document this?

   • A) Dyspnea on exertion

   • B) Orthopnea

   • C) Paroxysmal nocturnal dyspnea (PND)

   • D) Eupnea

   • Answer: C. $PND$ is a sudden shortness of breath that occurs during sleep.

8. When percussing the posterior thorax, the nurse identifies a dull sound over the lower right lobe. This likely indicates:

   • A) Normal lung tissue

   • B) Pneumothorax

   • C) Pleural effusion or pneumonia

   • D) Asthma

   • Answer: C. Dullness indicates a solid or fluid-filled space where air should normally be.

9. Which component is found within the mediastinum?

   • A) Lungs

   • B) Heart

   • C) Diaphragm

   • D) Scapula

   • Answer: B. The mediastinum contains the heart, aorta, superior vena cava, lower esophagus, and trachea.

10. A nurse is assessing a patient's breathing and notes they can only finish half a sentence before needing to take a breath. This is known as:

    • A) Pursed-lip breathing

    • B) Word dyspnea

    • C) Tachypnea

    • D) Hypoventilation

    • Answer: B. Word dyspnea is documented by how many words a patient can speak before pausing (e.g., "three-word dyspnea").

11. An athlete's diaphragmatic excursion is measured at $8$ cm. How should the nurse interpret this?

    • A) Abnormal (too high)

    • B) Abnormal (too low)

    • C) Normal for an athlete

    • D) Indicative of consolidation

    • Answer: C. Normal excursion is $3-5$ cm, but in well-conditioned athletes, it can reach $7-8$ cm.

12. The nurse is performing a respiratory assessment on a female patient. Which breathing pattern is typically expected?

    • A) Abdominal breathing

    • B) Thoracic breathing

    • C) Cheyne-Stokes

    • D) Kussmaul breathing

    • Answer: B. Generally, women tend to exhibit thoracic breathing, while men exhibit abdominal breathing.

13. During the inspection of a patient with emphysema, the nurse notes the AP diameter of the chest is equal to the lateral diameter. This is documented as:

    • A) Pectus excavatum

    • B) Barrel chest

    • C) Pectus carinatum

    • D) Kyphosis

    • Answer: B. A barrel chest (1:1 ratio) results from air trapping in the alveoli.

14. What is the movemement of gases from high concentration to low concentration across the alveolar-capillary membrane called?

    • A) Ventilation

    • B) Transportation

    • C) Diffusion

    • D) Perfusion

    • Answer: C. Diffusion refers to the exchange of gas at the membrane level.

15. A patient has an oxygen saturation of $88\%$. Which finding would suggest this is a chronic rather than acute issue?

    • A) Respiratory rate of $22$

    • B) Confusion

    • C) Barrel chest and pursed-lip breathing

    • D) Use of accessory muscles

    • Answer: C. Barrel chest and pursed-lip breathing are characteristic of chronic conditions like $COPD$.

16. At what anatomical level does the trachea bifurcate into the right and left main-stem bronchi?

    • A) $C7$

    • B) $T4$ or $T5$

    • C) $T10$

    • D) Angle of Louis

    • Answer: B. The trachea splits at the level of the sternal angle ($T4$ or $T5$).

17. A patient presents with a persistent cough and hemoptysis (coughing up blood). Which condition should the nurse screen for?

    • A) Asthma

    • B) Lung Cancer

    • C) Acute Bronchitis

    • D) Atelectasis

    • Answer: B. Hemoptysis is a significant clinical find in lung cancer.

18. Which rib pairs are referred to as 'floating ribs'?

    • A) $1-7$

    • B) $8-10$

    • C) $11-12$

    • D) $1-3$

    • Answer: C. Ribs $11$ and $12$ are unattached anteriorly and are called floating ribs.

19. What is the normal range for oxygen saturation ($SaO_2$)?

    • A) $90\%-95\%$

    • B) $95\%-100\%$

    • C) $85\%-90\%$

    • D) $98\%-102\%$

    • Answer: B. The normal healthy range is generally $95\%-100\%$.

20. During the health history, a patient mentions using Ginseng. Why is this detail important for the nurse to note?

    • A) It causes wheezing

    • B) It can interact with other medications and is an herbal supplement

    • C) It is a primary treatment for COPD

    • D) It causes hyperresonance

    • Answer: B. Nurses must document all $OTC$ and herbal supplements to assess for potential drug-herb interactions.