What is the recommended management for a patient with Chronic Obstructive Pulmonary Disease (COPD) on Continuous Positive Airway Pressure (CPAP) therapy?

Management of COPD Patients on CPAP Therapy

Critical Clarification: CPAP vs. NPPV in COPD

CPAP alone is generally NOT the appropriate ventilatory support for COPD patients—you should be using Non-Invasive Positive Pressure Ventilation (NPPV) which combines CPAP with Pressure Support Ventilation (PSV). 1

When to Use NPPV in COPD

NPPV should be considered when pH is less than 7.26 with rising PaCO2 despite optimal medical therapy and controlled oxygen. 1

• The optimal mode is CPAP (4-8 cmH2O) PLUS PSV (10-15 cmH2O), not CPAP alone 1
• NPPV has been shown in randomized controlled trials to reduce the number of patients requiring invasive ventilation and shorten hospital length of stay 1
• Most effective when used earlier than the pH <7.26 threshold 1
• Should be delivered in a controlled environment such as intermediate ICUs or high-dependency units 1

Contraindications to NPPV

Patients less likely to respond well to NPPV include: 1

• Confused patients
• Those with large volume of secretions
• pH < 7.25 (should be in ICU with intubation readily available) 1

When to Intubate

Consider invasive mechanical ventilation for: 1

• NPPV failure (worsening ABGs/pH in 1-2 hours, or lack of improvement after 4 hours)
• Severe acidosis (pH < 7.25) with hypercapnia (PaCO2 > 60 mmHg)
• Life-threatening hypoxemia
• Tachypnea > 35 breaths/min

Comprehensive COPD Management While on Ventilatory Support

Optimize Bronchodilator Therapy

Patients with severe COPD requiring ventilatory support should be on combination β2-agonist and anticholinergic bronchodilators if they derive increased benefit. 1

• Deliver via nebulizer during acute exacerbations 1
• Consider adding theophyllines with careful monitoring for side effects 1, 2
• Up to 76% of COPD patients make important inhaler errors—verify proper technique 2

Oxygen Therapy Goals

Target SaO2 ≥90% and/or PaO2 ≥60 mmHg (8.0 kPa) without elevating PaCO2 by >10 mmHg (1.3 kPa) or lowering pH to <7.25. 1

• Start oxygen at low dose (24% by Venturi mask or 1-2 L/min by nasal cannulae) 1
• Monitor arterial blood gases regularly and adjust accordingly 1

Corticosteroids

Administer oral corticosteroids (typically 30mg daily for one week) during acute exacerbations if patient has documented previous response or airflow obstruction fails to respond to increased bronchodilator dose. 2

• Can usually be stopped abruptly after 7 days unless there are positive reasons for long-term usage 1
• An exacerbation while on oral corticosteroids does not necessarily indicate need for long-term inhaled corticosteroids 1

Antibiotics

Prescribe antibiotics if two or more of the following are present: increased breathlessness, increased sputum volume, or development of purulent sputum. 2

• Usually do not need to be continued for more than 7 days 1

Diuretics

Use diuretics if there is peripheral edema and raised jugular venous pressure. 1

• Use carefully to avoid reducing cardiac output and renal perfusion and creating electrolyte imbalance 1

Respiratory Stimulants

Doxapram may be considered in patients with acidosis (pH <7.26) and/or hypercapnia to tide the patient over for 24-36 hours until the underlying cause is controlled. 1

• However, NPPV may prove to be a better alternative 1
• Respiratory stimulants are generally not recommended for routine use in COPD 1

Critical Monitoring Parameters

During Acute Phase

Monitor the following closely: 1

• Arterial blood gases (fundamental for correct assessment and guidance of therapy) 1
• pH (>7.26 is a better predictor of survival than PaCO2 alone) 1
• Respiratory rate
• Mental status
• Secretion volume

Before Discharge

Check the following before discharge: 1

• FEV1 should be recorded
• Peak flow should be recorded twice daily until clinically stable
• Arterial blood gas tensions should be checked on room air in patients presenting with hypercapnic respiratory failure—this guides need for Long-Term Oxygen Therapy (LTOT) assessment 1

Long-Term Oxygen Therapy Considerations

LTOT improves survival in COPD patients with chronic respiratory failure and should be prescribed if PaO2 ≤55 mmHg (7.3 kPa) during a stable 3-4 week period despite optimal therapy. 1

• Should be used for minimum 15 hours/day, including during sleep 1
• Flow of 1.5-2.5 L/min through nasal cannulae is usually adequate to achieve PaO2 >60 mmHg (8.0 kPa) 1
• Generally not prescribed for patients who continue to smoke 1

Common Pitfalls to Avoid

• Do not use CPAP alone—combine with PSV for effective NPPV 1
• Avoid beta-blocking agents (including eyedrop formulations) 1, 2
• Do not use chest physiotherapy routinely in acute exacerbations—there are few data to support its use 1
• Neither age alone nor PaCO2 are good guides to outcome of assisted ventilation—pH is better 1
• Do not let misconceptions about difficulty of weaning preclude intubation when indicated—five-year outcomes are better than many doctors appreciate 1

Decision-Making for Invasive Ventilation

Factors Encouraging IPPV: 1

• Demonstrable remedial reason for current decline (e.g., pneumonia, drug overdose)
• First episode of respiratory failure
• Acceptable quality of life or habitual level of activity

Factors Discouraging IPPV: 1

• Previously documented severe COPD unresponsive to relevant therapy
• Poor quality of life (e.g., housebound despite maximal therapy)
• Severe co-morbidities (e.g., pulmonary edema, neoplasia)