What are the latest developments in respiratory therapy for patients with conditions such as chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS)?

Latest Developments in Respiratory Therapy

The most transformative recent advances for respiratory therapists include high-flow nasal cannula (HFNC) as an alternative to traditional oxygen therapy and NIV, targeted high-intensity NIV with normalization of PaCO2 for chronic hypercapnic COPD, prone positioning as a mortality-reducing intervention in severe ARDS, and lung-protective ventilation strategies with driving pressure monitoring.

High-Flow Nasal Cannula (HFNC): An Emerging Game-Changer

HFNC has emerged as a frontline respiratory support modality that bridges the gap between conventional oxygen therapy and noninvasive ventilation, offering superior patient tolerance and ease of use across all clinical settings. 1

Physiological Mechanisms

• HFNC reduces anatomical dead space and improves CO2 washout, reduces work of breathing, generates positive end-expiratory pressure, and delivers a constant FiO2 with optimal heat and humidification 1
• This technique effectively reduces dyspnea and improves oxygenation in respiratory failure from various etiologies, often preventing escalation to more invasive supports 1

Clinical Applications

• HFNC is now routinely used for de novo hypoxemic respiratory failure, COPD exacerbations, postintubation hypoxemia, and palliative respiratory care 1
• Recent studies indicate HFNC can benefit patients with acute hypercapnic respiratory failure, either instead of or in combination with NIV, though more research is needed before definitive recommendations 2, 3
• Emerging applications include domiciliary treatment of patients with stable COPD, which will become a major focus in coming years 1

Practical Considerations

• HFNC improves ventilatory efficiency and reduces work of breathing in severe COPD patients 2, 3
• Use should be individualized based on institutional resources and local experience with respiratory support therapies 3

Advanced NIV Strategies for Chronic Hypercapnic COPD

The 2020 American Thoracic Society guidelines recommend nocturnal NIV with targeted normalization of PaCO2 for patients with chronic stable hypercapnic COPD, representing a paradigm shift from previous approaches. 4

Key Recommendations

• Nocturnal NIV should be added to usual care for patients with chronic stable hypercapnic COPD (PaCO2 > 45 mmHg) 4
• NIV with targeted normalization of PaCO2 is specifically recommended, rather than lower-intensity approaches 4
• Patients should undergo screening for obstructive sleep apnea before initiating long-term NIV 4
• Do not initiate long-term NIV during acute-on-chronic hypercapnic respiratory failure hospitalization; instead, reassess at 2-4 weeks after resolution 4

Titration Approach

• In-laboratory overnight polysomnography is not recommended for NIV titration in these patients 4
• For patients with severe chronic hypercapnia and history of hospitalization for acute respiratory failure, long-term NIV may decrease mortality and prevent rehospitalization 4

NIV for Acute Hypercapnic Respiratory Failure in COPD

NIV remains the gold standard first-line intervention for acute hypercapnic respiratory failure in COPD exacerbations, with robust evidence showing 46% mortality reduction and 65% reduction in intubation risk. 5

Evidence-Based Benefits

• NIV reduces mortality risk by 46% (RR 0.54,95% CI 0.38-0.76; NNTB 12) and intubation risk by 65% (RR 0.36,95% CI 0.28-0.46; NNTB 5) 5
• Hospital length of stay is reduced by 3.39 days on average 5
• Benefits are similar for mild acidosis (pH 7.30-7.35) versus severe acidosis (pH < 7.30), and when applied in ICU versus ward settings 5

Clinical Application

• NIV is particularly indicated for COPD with respiratory acidosis pH 7.25-7.35 4
• NIV improves dyspnea, gas exchange, pH, and PaO2 within one hour 5
• Treatment intolerance occurs in approximately 11% more patients with NIV compared to usual care 5

Contraindications

• NIV should not be used in patients with impaired consciousness, severe hypoxemia, or copious respiratory secretions 4

Novel NIV Modalities

Newer ventilation modes including adaptive servo-ventilation, neutrally adjusted ventilatory assist (NAVA), and proportional assist ventilation improve patient-ventilator synchrony and comfort. 6

Advanced Modes

• NAVA improves trigger and cycle asynchrony compared to traditional BiPAP 6
• Proportional assist ventilation prevents increased respiratory rate and distress by increasing tidal volume proportionally with patient effort 6
• Adaptive servo-ventilation treats central and complex sleep apnea 6

Proportional Assist Ventilation

• In COPD patients with chronic respiratory failure, proportional assist ventilation enables higher training intensity during pulmonary rehabilitation, leading to greater maximal exercise capacity and true physiologic adaptation 4

ARDS Management: Critical Updates

Lung-Protective Ventilation Parameters

Strict adherence to low tidal volume ventilation (4-8 mL/kg predicted body weight) with plateau pressure <30 cmH2O remains the cornerstone of ARDS management, reducing relative mortality risk by 21%. 7, 8

• Driving pressure (plateau pressure minus PEEP) should be monitored and minimized, with values <15 cmH2O associated with better outcomes 8
• Higher PEEP strategies (10-15 cmH2O or higher) for moderate to severe ARDS (PaO2/FiO2 <200 mmHg) reduce mortality (adjusted RR 0.90,95% CI 0.81-1.00) 8

Respiratory Rate and Timing in ARDS

• The time constant in ARDS is typically prolonged to 0.5-1.5 seconds, requiring expiratory times of at least 3-5 time constants (1.5-7.5 seconds) to prevent auto-PEEP 8
• Respiratory rate should be reduced to 25-30 breaths/min when possible to allow adequate expiratory time 8
• Inspiratory time should be set to 40-50% of the respiratory cycle 8

Prone Positioning: A Mortality-Reducing Intervention

Prone positioning for ≥12-16 hours daily should be implemented immediately in all patients with severe ARDS (PaO2/FiO2 <150 mmHg), as it demonstrates clear mortality benefit. 7, 8

• Prone positioning improves ventilation-perfusion matching and reduces ventilator-induced lung injury by redistributing transpulmonary pressure more evenly 8
• Delaying prone positioning in severe ARDS is a critical pitfall to avoid 7

Neuromuscular Blockade

• Consider neuromuscular blockade for 24-48 hours to improve ventilator synchrony and potentially reduce mortality in severe ARDS 7
• Neuromuscular blocking agents prevent patient-ventilator dyssynchrony and expiratory efforts that cause derecruitment 8

Adjunctive Supportive Care in ARDS

• Elevate head of bed ≥30 degrees at all times to reduce aspiration risk 7
• Initiate enteral nutrition with formulations containing antioxidants and anti-inflammatory amino acids, which may improve gas exchange and reduce mechanical ventilation duration 7
• Minimize sedation when possible to allow assessment and prevent prolonged weakness 7

Critical Pitfalls in ARDS Management

• Avoid high-frequency oscillatory ventilation (HFOV) as it may worsen hemodynamics and increase mortality 8
• Monitor for right ventricular dysfunction when increasing inspiratory time or PEEP, as prolonged positive pressure can increase RV afterload 8
• Do not overlook non-pulmonary sources of fever, including nosocomial sinusitis, which contributes to VAP development and carries independent mortality risk 7

Pulmonary Rehabilitation: Enhanced Evidence Base

Pulmonary rehabilitation significantly improves symptoms, quality of life, physical and emotional participation in daily activities, and reduces readmissions and mortality, particularly when initiated early after exacerbation. 4

Timing Considerations

• Pulmonary rehabilitation can reduce readmissions and mortality in patients after recent exacerbation (<4 weeks from hospitalization) 4
• However, initiating pulmonary rehabilitation before hospital discharge may compromise survival 4

Adjunctive Therapies

• Noninvasive positive pressure ventilation (NPPV) during rehabilitation in severe COPD with chronic respiratory failure improves exercise tolerance and quality of life, presumably through resting respiratory muscles at night 4
• Inspiratory muscle training should be considered as adjunctive therapy primarily in patients with suspected or proven respiratory muscle weakness 4
• Neuromuscular electrical stimulation (NMES) benefits bed-bound patients receiving mechanical ventilation with marked peripheral muscle dysfunction 4

COPD Management Updates

Initial Management of New Emphysema

For newly diagnosed emphysema, confirm diagnosis with post-bronchodilator spirometry (FEV1/FVC <70%), initiate smoking cessation with combined pharmacotherapy and behavioral support, and start LABA/LAMA combination therapy for patients with exacerbation history. 9

• Smoking cessation with varenicline, bupropion, or nortriptyline combined with behavioral support achieves long-term quit rates up to 25% 4, 9
• LABA/LAMA combination is first-line for patients with exacerbation history (Groups C and D) 9
• Refer patients with high symptom burden to pulmonary rehabilitation immediately 9

Oxygen Therapy

• Long-term oxygen therapy (>15 hours/day) improves survival only in severe resting hypoxemia (PaO2 ≤55 mmHg or SaO2 ≤88%) 4, 9
• Long-term oxygen should not be prescribed routinely for stable COPD with resting or exercise-induced moderate desaturation 4

Vaccination

• Influenza vaccination reduces serious illness, death, risk of ischemic heart disease, and total exacerbations 4
• Pneumococcal vaccinations (PCV13 and PPSV23) are recommended for all patients ≥65 years 4

Advanced Interventions

• In patients with severe chronic hypercapnia and history of hospitalization for acute respiratory failure, long-term NIV may decrease mortality and prevent rehospitalization 4
• For select patients with advanced emphysema refractory to optimized medical care, surgical (lung volume reduction surgery, bullectomy, lung transplantation) or bronchoscopic interventional treatments may be beneficial 4