6.1 Chronic and Acute Respiratory Disorders

6.1 Chronic and Acute Respiratory Disorders

Adult respiratory disorders represent one of the most frequent causes of acute hospital admissions and intensive care unit consultations in clinical nursing. Effective respiratory care demands a deep understanding of pulmonary gas exchange dynamics, ventilatory mechanics, pharmacotherapeutic principles, and prompt recognition of physiological deterioration. This section examines the clinical management of Chronic Obstructive Pulmonary Disease (COPD), acute asthma exacerbations, pneumonia, pulmonary embolism, and closed chest tube drainage systems.

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Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is a progressive, partially reversible inflammatory lung disease characterized by persistent airflow limitation. The underlying pathophysiology encompasses two distinct yet frequently overlapping clinical phenotypes:

Chronic Bronchitis vs. Emphysema

Spirometry represents the gold standard diagnostic tool: a post-bronchodilator FEV1/FVC ratio < 0.70 establishes non-reversible obstructive airflow limitation.

The Hypoxic Drive & Controlled Oxygen Titration

In healthy individuals, the respiratory center in the medulla oblongata regulates minute ventilation based on arterial carbon dioxide tension (PaCO2) and cerebrospinal fluid (CSF) pH detected by central chemoreceptors. Even minor elevations in PaCO2 trigger rapid increases in respiratory rate and tidal volume.

In patients with advanced COPD and chronic hypercapnic respiratory failure, persistent hypercapnia causes renal retention of bicarbonate (HCO3-), buffering CSF pH. Consequently, central chemoreceptors become desensitized to chronic hypercapnia. The patient's primary stimulus to breathe shifts to peripheral chemoreceptors situated in the carotid bodies and aortic arch, which respond to hypoxemia (low arterial oxygen tension, PaO2).

Normal Chemoreception:     Elevated PaCO2 / Low CSF pH  --->  Central Chemoreceptors (Medulla)  --->  Stimulates Breathing
Chronic COPD Adaptation:   Blunted Central Response      --->  Peripheral Chemoreceptors (Carotid) --->  Hypoxic Drive (PaO2 < 60 mmHg)

• Oxygen-Induced Hypercapnia: When excessive high-flow oxygen is administered to a patient dependent on hypoxic drive, the sudden elevation of PaO2 abolishes the hypoxemic drive to breathe, suppresses ventilation, and worsens V/Q mismatch via the release of hypoxic pulmonary vasoconstriction. Additionally, the Haldane effect causes deoxygenated hemoglobin to release bound carbon dioxide into the plasma as it becomes oxygen-saturated, causing severe acute-on-chronic hypercapnic respiratory failure, carbon dioxide narcosis (somnolence, lethargy, asterixis/flapping tremor), and respiratory arrest.
• Oxygen Therapy Protocol: Supplemental oxygen must be precisely titrated to achieve a target SpO2 of 88% to 92% (corresponding to a PaO2 of approximately 60 mmHg). The Venturi mask is the preferred delivery interface because it provides a fixed, reliable fraction of inspired oxygen (FiO2 24% to 28%) regardless of the patient's respiratory rate or depth. If a nasal cannula is utilized, flow rates should be maintained at 1 to 2 L/min.

Pursed-Lip Breathing Technique

Pursed-lip breathing is a fundamental self-management technique that prevents dynamic airway collapse during expiration:

1. Technique: The patient inhales slowly through the nose with the mouth closed for a count of two, puckers the lips as if about to whistle or blow out a candle, and exhales slowly and passively through pursed lips for a count of four (maintaining an inspiration-to-expiration [I:E] ratio of 1:2 or 1:4).
2. Mechanism: Exhaling against the narrow resistance of pursed lips generates continuous positive end-expiratory pressure (PEEP) back throughout the tracheobronchial tree. This internal splinting pressure keeps fragile, floppy bronchioles open during exhalation, prevents premature small-airway collapse, reduces trapped alveolar gas, and promotes maximal carbon dioxide elimination.

Pharmacotherapy for Obstructive Pulmonary Diseases

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Acute Asthma Exacerbation

Asthma is a chronic inflammatory disorder of the conducting airways characterized by bronchial hyperresponsiveness, reversible airway obstruction, mucosal edema, and tenacious mucus plug formation.

Peak Expiratory Flow (PEF) Zone Monitoring

Self-management plans utilize the patient's personal best peak expiratory flow rate:

• Green Zone (80% to 100% of personal best): Indicates good control. The patient experiences no nighttime symptoms or exercise limitations; continue regular maintenance controller medications.
• Yellow Zone (50% to 79% of personal best): Signals caution and acute airway narrowing. The patient experiences cough, wheezing, or chest tightness. Action: administer 2 to 4 puffs of quick-relief SABA every 20 minutes for up to 3 doses; if PEF does not return to the green zone, initiate temporary oral corticosteroid burst and notify the provider.
• Red Zone (< 50% of personal best): Medical emergency denoting severe obstruction. The patient exhibits resting dyspnea and retractions. Action: immediately inhale high-dose rescue SABA via metered-dose inhaler with spacer or nebulizer and seek immediate emergency medical care.

Clinical Manifestations & The "Silent Chest" Phenomenon

Severe asthma exacerbations present with tachypnea, expiratory and inspiratory wheezes, diaphoresis, intercostal and supraclavicular retractions, speaking in broken words or phrases, and pulsus paradoxus (an abnormal decrease in systolic blood pressure > 10 mmHg during spontaneous inspiration, caused by excessive intrathoracic pressure swings compromising left ventricular stroke volume).

[!CAUTION] The Silent Chest Phenomenon: During severe status asthmaticus, the sudden disappearance of audible wheezing and severely diminished breath sounds in an exhausted, tachypneic patient is an ominous clinical emergency. It does NOT indicate clinical improvement; rather, it proves that bronchoconstriction and mucus plugging have become so profound that airflow velocity is insufficient to generate acoustic wheezing. The patient is in imminent respiratory arrest and requires emergency endotracheal intubation and mechanical ventilatory support.

Stepped Emergency Pharmacotherapy

1. Oxygen Therapy: Administer high-flow supplemental oxygen via non-rebreather mask or nasal cannula to maintain an SpO2 >= 93% to 95% (>= 95% in pregnant patients or patients with co-existing cardiac disease).
2. Inhaled Bronchodilators: Continuous or back-to-back nebulization of high-dose SABA (Albuterol 2.5 to 5.0 mg) combined with SAMA (Ipratropium bromide 0.5 mg) every 20 minutes for 3 cycles.
3. Systemic Corticosteroids: Intravenous Methylprednisolone (40 to 60 mg IV) or oral Prednisone (40 to 60 mg orally) initiated promptly; systemic steroids halt the inflammatory cascade and restore beta-2 receptor sensitivity, with clinical benefits emerging within 4 to 6 hours.
4. Intravenous Magnesium Sulfate: 1.0 to 2.0 grams IV infused over 20 minutes is indicated for severe, life-threatening exacerbations failing to respond to initial inhaled bronchodilators. Magnesium acts as a physiological calcium antagonist, blocking calcium influx into bronchial smooth muscle cells and promoting immediate, profound bronchodilation.

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Pneumonia: Classification, Risk Stratification & Nursing Care

Pneumonia is an acute parenchymal infection involving the alveolar spaces, interstitial tissues, and bronchioles, resulting in exudative alveolar consolidation.

Clinical Classifications

• Community-Acquired Pneumonia (CAP): Acquired outside healthcare settings or diagnosed within < 48 hours of hospital admission. Streptococcus pneumoniae (pneumococcus) is the predominant bacterial pathogen.
• Hospital-Acquired Pneumonia (HAP): Develops >= 48 hours after hospital admission, which was not incubating at the time of admission. Pathogens frequently involve multidrug-resistant organisms including Pseudomonas aeruginosa, Methicillin-Resistant Staphylococcus aureus (MRSA), and Klebsiella pneumoniae.
• Ventilator-Associated Pneumonia (VAP): Arises >= 48 hours following endotracheal intubation.

The CURB-65 Severity Scoring Tool

The CURB-65 criteria is an evidence-based clinical tool used to predict 30-day mortality and determine whether an adult patient with CAP requires outpatient care, general ward admission, or intensive care:

• Score 0 to 1: Low risk (mortality < 3%); suitable for outpatient treatment with oral antimicrobial therapy.
• Score 2: Intermediate risk (mortality ~9%); requires short inpatient hospitalization or closely monitored outpatient treatment.
• Score 3 to 5: High risk (mortality 15% to 40%); mandates immediate inpatient hospital admission, with scores of 4 or 5 evaluated for direct admission to an intensive care unit (ICU).

Evidence-Based Nursing Interventions

1. Microbiological Diagnostics: Sputum specimens for Gram stain and culture and two sets of blood cultures must be collected PRIOR to administering the first dose of antimicrobial therapy. However, antibiotic initiation must never be delayed beyond critical institutional windows (e.g., within 1 hour for septic shock or within 4 hours for stable pneumonia) if sputum collection is impeded.
2. Incentive Spirometry (IS): The patient must perform 10 breaths per hour while awake. The nurse instructs the patient to sit fully upright in High-Fowler's position, exhale completely, tightly seal lips around the mouthpiece, inhale slowly and deeply to raise the internal indicator, hold the breath for 3 to 5 seconds at maximal inspiration, and then exhale passively. This maneuver re-expands atelectatic alveoli, improves surfactant release, and mobilizes secretions. Follow each cycle with controlled voluntary coughing.
3. Therapeutic Positioning ("Good Lung Down"): In unilateral pneumonia, the patient should be positioned in the lateral decubitus position with the unaffected (healthy) lung dependent (facing down). Gravitational forces increase pulmonary perfusion to the dependent lung; placing the well-ventilated healthy lung in the dependent position maximizes ventilation-perfusion (V/Q) matching, improving systemic arterial oxygenation.
   • Critical Exceptions: If the patient has a lung abscess or massive hemoptysis, the affected (diseased) lung must be positioned down to prevent purulent exudate or blood from spilling across the carina into the healthy lung.
4. Systemic Hydration & Pulmonary Toilet: Maintain oral and intravenous hydration (2 to 3 L/day unless restricted by congestive heart failure or end-stage renal disease) to thin viscous tracheobronchial secretions, facilitating mucociliary clearance.

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Pulmonary Embolism (PE)

Pulmonary Embolism (PE) occurs when an endogenous or exogenous thrombus, fat droplet, air bubble, or amniotic fluid dislodges and occludes one or more pulmonary arterial branches, compromising alveolar perfusion.

Pathogenesis & Virchow's Triad

Thrombus formation is driven by the three pathophysiological factors of Virchow's Triad:

1. Venous Stasis: Immobility, prolonged bed rest, major orthopedic surgery, stroke, long-haul flights.
2. Endothelial Vascular Injury: Surgery, orthopedic trauma, central venous catheterization, smoking, hypertension.
3. Hypercoagulability: Active malignancy, oral contraceptives, hormone replacement therapy, pregnancy, Factor V Leiden mutation, antiphospholipid syndrome.

Clinical Presentation

Classic symptoms include sudden-onset pleuritic chest pain that worsens with inspiration, unexplained tachypnea (RR > 20 bpm), tachycardia (HR > 100 bpm), acute dyspnea, hemoptysis, extreme apprehension or impending doom, and syncope (indicating massive central saddle embolism). Electrocardiogram (ECG) commonly demonstrates sinus tachycardia; the classic S1Q3T3 pattern (deep S wave in lead I, prominent Q wave in lead III, and T-wave inversion in lead III) reflects acute right ventricular strain.

Diagnostic Pathway

• Computed Tomography Pulmonary Angiography (CTPA): The definitive gold-standard diagnostic imaging modality.
• D-Dimer Assay: High sensitivity but low clinical specificity. A normal D-dimer (< 500 ng/mL FEU) safely rules out PE in low-to-intermediate probability patients; an elevated D-dimer requires diagnostic CTPA.
• Ventilation-Perfusion (V/Q) Scan: Utilized when iodinated radiopaque contrast is contraindicated due to severe renal impairment (eGFR < 30 mL/min) or documented anaphylactic contrast allergy.

Anticoagulation & Thrombolytic Protocols

PE Suspected / Confirmed ---> Hemodynamically Unstable? (SBP < 90 mmHg)
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      +---> YES: Massive PE ---> Immediate Thrombolysis (Alteplase 100 mg IV over 2 hr) or Surgical Embolectomy
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      +---> NO: Submassive / Stable PE ---> Weight-based Unfractionated Heparin (UFH) IV or LMWH (Enoxaparin)

1. Unfractionated Heparin (UFH): Administered as an initial weight-based IV bolus (80 units/kg) followed by continuous infusion (18 units/kg/hr). The infusion rate is titrated according to the hospital's nomogram to achieve a therapeutic activated partial thromboplastin time (aPTT) of 1.5 to 2.5 times the laboratory control baseline (typically 60 to 80 seconds). The antidote for heparin reversal is Protamine Sulfate (1 mg neutralizes approximately 100 units of unfractionated heparin).
2. Low-Molecular-Weight Heparin (LMWH): Enoxaparin (1 mg/kg subcutaneously every 12 hours) provides predictable bioavailability without requiring routine aPTT monitoring.
3. Thrombolytic Therapy (Alteplase / tPA): Recombinant tissue plasminogen activator (100 mg IV administered over 2 hours) is indicated for massive, hemodynamically unstable PE manifested by sustained systemic hypotension (systolic BP < 90 mmHg), cardiogenic shock, or pulseless electrical activity (PEA). Thrombolysis directly lyses the clot, rapidly restoring pulmonary perfusion.

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Closed Chest Tube Drainage Systems

Chest tube thoracostomy restores physiological negative intrapleural pressure (-4 to -8 cm H2O) by evacuating pathological air (pneumothorax), blood (hemothorax), or purulent fluid (empyema) from the pleural cavity.

The Three-Chamber Drainage System Architecture

[ PATIENT ]
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    v
[ Chamber 1: Collection ] ---> [ Chamber 2: Water Seal ] ---> [ Chamber 3: Suction Control ] ---> [ Wall Suction ]
  (Measures drainage volume,     (2 cm sterile water; one-way    (Wet: -20 cm H2O gentle bubbling;
   color, and hourly rate)        valve; exhibits tidaling)        Dry: mechanical dial setting)

1. Collection Chamber: Receives fluid and blood directly from the patient's pleural space. The nurse documents fluid volume, marks the level directly on the plastic unit face at scheduled intervals, and notes drainage character. Drainage exceeding > 100 to 200 mL/hr of frank bloody output in an adult is an urgent clinical red flag indicating active intrathoracic hemorrhage that must be immediately reported to the thoracic surgeon.
2. Water-Seal Chamber: Contains exactly 2 cm of sterile water. It acts as a one-way valve allowing air and fluid to exit the pleural cavity while preventing ambient atmospheric air from re-entering.
   • Tidaling (Normal): The sterile fluid level rises during spontaneous inspiration (as negative intrapleural pressure increases) and falls during spontaneous expiration. On positive-pressure mechanical ventilation, this pattern is reversed (falls with inspiration, rises with expiration). Cessation of tidaling indicates either that the lung has completely re-expanded against the chest wall or that the drainage tubing is kinked, clotted, or occluded.
   • Air Leak Bubbling: Intermittent bubbling during expiration, coughing, or sneezing is expected during the acute evacuation of a pneumothorax. However, continuous, persistent bubbling across all respiratory phases indicates an air leak in the system—either an anatomical leak (bronchopleural fistula) or an external circuit leak (loose connection or cracked canister).
3. Suction Control Chamber:
   • Wet Suction Units: Filled with sterile water to the prescribed negative pressure level (typically -20 cm H2O). The wall vacuum source is adjusted until gentle, rolling bubbling is observed. Vigorous bubbling does NOT increase the negative suction pressure; it only accelerates water evaporation from the chamber and generates unnecessary noise.
   • Dry Suction Units: Utilize an internal mechanical spring or dial mechanism set to the desired negative pressure (e.g., -20 cm H2O); an expanding bellows indicator confirms functional suction.

Critical Nursing Prohibitions & Emergency Protocols

• NEVER Milk or Strip Chest Drainage Tubing: Stripping generates extreme, dangerous negative intrapleural pressures (exceeding -400 cm H2O), which traumatizes delicate pleural membranes, damages pulmonary parenchyma, dislodges clots, and can invert the diaphragm.
• NEVER Routinely Clamp Chest Tubes: Clamping prevents air and fluid from venting, rapidly converting a simple pneumothorax into a fatal tension pneumothorax. Clamping is strictly limited to brief seconds when replacing a full drainage unit or when systematically isolating the site of a persistent air leak.
• Accidental Disconnection from the Drainage Unit: If the chest tube becomes disconnected from the collection canister, the nurse must immediately submerge the distal end of the chest tube 2 to 4 cm into an open bottle of sterile water or sterile normal saline maintained at the bedside. This creates a temporary emergency water seal, allowing air to escape while preventing atmospheric air from rushing into the pleural space, until a new sterile drainage unit is connected.
• Accidental Dislodgement from the Chest Wall: If the chest tube is inadvertently pulled out of the patient's chest, the nurse must immediately instruct the patient to exhale fully and cough, then cover the insertion site with a sterile petroleum (Vaseline) gauze dressing taped securely on THREE SIDES ONLY. Taping on three sides creates an emergency flutter valve: during expiration, air escapes around the unsealed fourth edge; during inspiration, the dressing seals against the skin, preventing atmospheric air entry and preventing a tension pneumothorax. Never tape all four sides.