8.3 Nursing Care in Acute Respiratory Distress & Chronic Obstructive Pulmonary Disease
Key Takeaways
- Chronic Obstructive Pulmonary Disease (COPD) features airflow limitation and loss of elastic recoil, requiring controlled low-flow oxygen (target SpO2 88–92%), pursed-lip breathing, and early recognition of acute exacerbations (AECOPD).
- Acute Respiratory Distress Syndrome (ARDS) is non-cardiogenic pulmonary edema causing severe refractory hypoxemia (PaO2/FiO2 ≤ 300 mmHg) and reduced lung compliance, requiring lung-protective ventilation and prone positioning protocols.
- Pharmacological therapy in Singapore clinical practice follows MOH CPGs: bronchodilators (SABA/LABA, SAMA/LAMA), systemic corticosteroids for exacerbations, inhaled steroids, and targeted antimicrobials when sputum purulence is present.
- Prone positioning in ARDS (≥ 16–18 hours/day) recruits dorsal alveoli and improves V/Q matching, requiring specialized multi-person turning protocols to prevent accidental extubation, line displacement, and facial pressure injuries.
8.3 Nursing Care in Acute Respiratory Distress & Chronic Obstructive Pulmonary Disease
Pathophysiology and Clinical Presentation of COPD vs. ARDS
Understanding the pathophysiology of Chronic Obstructive Pulmonary Disease (COPD) and Acute Respiratory Distress Syndrome (ARDS) is critical for effective clinical assessment and tailored nursing care.
Chronic Obstructive Pulmonary Disease (COPD)
COPD is a common, preventable, and treatable chronic disease characterized by persistent respiratory symptoms and airflow limitation due to airway and/or alveolar abnormalities caused by significant exposure to noxious particles or gases (primarily cigarette smoke in Singapore). It encompasses two primary clinical phenotypes:
- Emphysema: Permanent enlargement of air spaces distal to terminal bronchioles accompanied by destruction of alveolar walls and capillary beds. Loss of elastic recoil causes air trapping, hyperinflation, flattened diaphragm, and barrel chest.
- Chronic Bronchitis: Chronic airway inflammation resulting in goblet cell hyperplasia, mucus hypersecretion, and persistent productive cough for at least 3 months per year in 2 consecutive years.
In chronic severe COPD, persistent hypercapnia leads to desensitization of central chemoreceptors in the medulla. The primary stimulus to breathe shifts to peripheral chemoreceptors sensitive to arterial hypoxemia (hypoxic drive).
Acute Respiratory Distress Syndrome (ARDS)
ARDS is an acute, diffuse inflammatory lung injury triggered by direct pulmonary insults (severe pneumonia, gastric aspiration, pulmonary contusion) or indirect systemic insults (sepsis, severe acute pancreatitis, major trauma with massive blood transfusion). Cytokine cascades increase alveolar-capillary membrane permeability, leading to protein-rich non-cardiogenic pulmonary edema, surfactant inactivation, micro-atelectasis, severe ventilation-perfusion ($V/Q$) mismatch, and refractory hypoxemia.
Berlin Definition Diagnostic Criteria for ARDS:
1. Onset: Acute within 1 week of a known clinical insult.
2. Chest Imaging: Bilateral opacities not fully explained by heart failure or fluid overload.
3. PaO2/FiO2 Ratio (on PEEP >= 5 cmH2O):
- Mild ARDS: 200 < PaO2/FiO2 <= 300 mmHg
- Moderate ARDS: 100 < PaO2/FiO2 <= 200 mmHg
- Severe ARDS: PaO2/FiO2 <= 100 mmHg
Clinical Assessment and Arterial Blood Gas (ABG) Monitoring
Signs of Impending Respiratory Failure
- Tachypnea: Respiratory rate $> 30$ breaths/min.
- Accessory Muscle Use: Intercostal retractions, sternocleidomastoid contraction, nasal flaring.
- Paradoxical Abdominal Breathing: Inward movement of the abdomen during inspiration—a sign of diaphragmatic fatigue and imminent respiratory arrest.
- Altered Mental State: Agitation/anxiety (hypoxia) or progressive somnolence/asterixis (hypercapnic encephalopathy).
Classification of Respiratory Failure via ABG
| Classification | ABG Diagnostic Criteria | Common Clinical Causes | Primary Pathophysiology |
|---|---|---|---|
| Type I (Hypoxemic) | $PaO_2 < 60 ext{ mmHg}$ with normal or low $PaCO_2$ ($< 45 ext{ mmHg}$) | ARDS, severe pneumonia, pulmonary embolism, cardiogenic pulmonary edema | Severe $V/Q$ mismatching and intrapulmonary shunting |
| Type II (Hypercapnic) | $PaO_2 < 60 ext{ mmHg}$ AND $PaCO_2 > 45 ext{ mmHg}$ with $pH < 7.35$ | Acute Exacerbation of COPD (AECOPD), severe asthma, Guillain-Barré, opioid overdose | Alveolar hypoventilation and respiratory muscle exhaustion |
Evidence-Based Nursing Interventions for COPD Management
Controlled Oxygen Titration
Administer controlled low-flow oxygen via a Venturi mask (24% or 28% $FiO_2$) targeting an $SpO_2$ of 88% – 92%. Uncontrolled high-flow oxygen suppresses the peripheral hypoxic drive, leading to acute hypoventilation, $CO_2$ retention, carbon dioxide narcosis, and coma.
Patient Positioning & Airway Clearance
- Tripod Position: Position the patient sitting upright leaning forward with arms resting on an overbed table. This fixes the shoulder girdle, optimizing the mechanical advantage of accessory chest muscles and depressing the diaphragm.
- Pursed-Lip Breathing: Instruct the patient to inhale slowly through the nose for 2 seconds and exhale through puckered lips for 4 seconds. This generates positive back-pressure in the airways during expiration, keeping collapsible small airways open and reducing air trapping.
- Controlled Huff Coughing: A forced expiratory technique (sighing out with an open glottis) that mobilizes secretions from peripheral to central airways without causing airway collapse.
Pharmacotherapy in AECOPD (Singapore MOH CPG)
- Short-Acting Bronchodilators: Salbutamol (SABA) combined with Ipratropium bromide (SAMA) via nebulizer or MDI with spacer every 2 to 4 hours.
- Systemic Corticosteroids: Oral Prednisolone (30–40 mg daily for 5 days) or IV Hydrocortisone to reduce endobronchial inflammation and shorten recovery time.
- Targeted Antimicrobials: Indicated when the patient exhibits all three cardinal symptoms (increased dyspnea, increased sputum volume, and increased sputum purulence) per MOH CPG guidelines.
- Non-Invasive Ventilation (NIV / BiPAP): First-line intervention for acute hypercapnic respiratory failure ($pH < 7.35$, $PaCO_2 > 45 ext{ mmHg}$) failing maximal medical therapy.
Evidence-Based Nursing Management in ARDS
Lung-Protective Mechanical Ventilation
Nurses managing ARDS in Singapore ICUs monitor and adhere to protective ventilator parameters:
- Low Tidal Volume Ventilation: Set at 4 – 8 mL/kg of Predicted Body Weight (PBW) (not actual weight) to prevent volutrauma and biotrauma.
- Plateau Pressure ($P_{plat}$) Target: Kept strictly $< 30 ext{ cmH}_2O$.
- High PEEP Titration: $PEEP$ of 10–20 $cmH_2O$ is applied to recruit collapsed dorsal alveoli and prevent atelectrauma.
Prone Positioning Protocol
Prone positioning is indicated for severe ARDS ($PaO_2/FiO_2 < 150 ext{ mmHg}$). It shifts blood flow to better-ventilated anterior lung regions, recruits collapsed dorsal alveoli, and improves $V/Q$ matching.
Prone Positioning Safety Protocol:
- Duration: Minimum 16 to 18 consecutive hours per day in prone position.
- Turning Team: Minimum 4 to 5 staff members.
- Airway Leader: Dedicated doctor or senior ICU nurse controlling ETT at head of bed.
- Pre-Turn Checks: Stop tube feeding, aspirate stomach, secure lines/drains, apply silicone pads to bony prominences.
- Post-Turn Care: Turn head q2h, alternate arms in swimmer's position q2h, apply eye lubricant.
Discharge Education & Community Transition in Singapore
To prevent hospital readmissions across Singapore healthcare clusters (SingHealth, National Healthcare Group, National University Health System), nurses must provide structured discharge coaching:
- Inhaler Technique & Compliance: Verify correct metered-dose inhaler (MDI) technique with a spacer prior to discharge.
- Exacerbation Action Plan: Educate patient to recognize early infection triggers (change in sputum color to green/yellow, increased shortness of breath) and initiate prescribed emergency antibiotics/steroids.
- Immunization: Recommend annual Influenza and Pneumococcal (PCV13/PPSV23) vaccinations per the Singapore National Adult Immunization Schedule (NAIS).
- Pulmonary Rehabilitation: Refer to multidisciplinary outpatient pulmonary rehabilitation programs for structured exercise training and nutritional support.
A patient with acute severe ARDS is placed on mechanical ventilation. The arterial blood gas (ABG) shows PaO2 of 55 mmHg on an FiO2 of 0.80 (80%), yielding a PaO2/FiO2 ratio of 68.75 mmHg. The intensivist orders prone positioning. Which nursing action is essential prior to executing the prone turn?
A 72-year-old female with severe COPD is admitted to the medical ward with an acute exacerbation. She presents with severe dyspnea, barrel chest, and anxiety. Which breathing technique should the nurse instruct the patient to perform to decrease air trapping and reduce respiratory rate?
The nurse is reviewing the arterial blood gas (ABG) results of a patient admitted with severe sepsis who developed acute dyspnea: pH 7.28, PaCO2 32 mmHg, PaO2 52 mmHg, HCO3 16 mmol/L, SpO2 84% on 10 L/min via simple mask. How should the nurse interpret these ABG results?