What are the initial ventilator settings for a Chronic Obstructive Pulmonary Disease (COPD) patient in Type 2 respiratory failure?

Initial Ventilator Settings for COPD Patients in Type 2 Respiratory Failure

For COPD patients in Type 2 respiratory failure, use noninvasive positive pressure ventilation (NPPV) with bi-level pressure support settings of IPAP 10-15 cmH2O and EPAP 4-8 cmH2O, with a backup rate of 10-12 breaths/min and target oxygen saturation of 88-92%. 1

Initial Assessment and Decision for Ventilation

• Mechanical ventilation should be considered when there is acidosis (pH < 7.35), hypercapnia (PaCO2 > 6-8 kPa or 45-60 mmHg), and respiratory rate > 24 breaths/min despite optimal medical therapy and oxygen administration 1
• Noninvasive ventilation is preferred over invasive ventilation whenever possible as it reduces mortality, need for intubation, and treatment failure 1, 2
• Arterial blood gases (ABGs) are fundamental for assessment and guiding therapy - obtain baseline ABGs before initiating ventilation 1

Oxygen Settings

• Target oxygen saturation of 88-92% to avoid worsening hypercapnia 1
• Prior to ABG availability, use 24% Venturi mask at 2-3 L/min, nasal cannulae at 1-2 L/min, or 28% Venturi mask at 4 L/min 1
• Avoid excessive oxygen use as it increases risk of respiratory acidosis if PaO2 is above 10.0 kPa due to previous excessive oxygen therapy 1

Ventilation Mode Selection

• Bi-level pressure support (combination of CPAP plus pressure support ventilation) is the most effective mode of NPPV for COPD patients 1
• Use Spontaneous/Timed (S/T) mode with backup rate if patient has frequent central apneas, inappropriately low respiratory rate, or fails to reliably trigger the device 1
• Consider Timed mode with fixed respiratory rate if S/T mode is not successful 1

Initial Pressure Settings

• Start with IPAP (inspiratory positive airway pressure) of 10-15 cmH2O 1
• Set EPAP (expiratory positive airway pressure) at 4-8 cmH2O 1
• The pressure difference between IPAP and EPAP (pressure support) should be at least 5 cmH2O 1
• Increase pressure support in 1-2 cmH2O increments if PCO2 remains elevated 1

Respiratory Rate and Timing Settings

• Set backup rate equal to or slightly less than patient's spontaneous sleeping respiratory rate (minimum of 10 breaths/min) 1
• If sleeping respiratory rate is unknown, use spontaneous awake respiratory rate 1
• Set inspiratory time (IPAP time) to achieve an I:E ratio of approximately 1:2 (30% IPAP time) for COPD patients to allow adequate time for exhalation 1
• For a respiratory rate of 12 breaths/min with 30% IPAP time, this equals 1.5 seconds inspiratory time and 3.5 seconds expiratory time 1

Monitoring and Adjustments

• Recheck ABGs after 30-60 minutes of ventilation (or if clinical deterioration occurs) 1
• If pH and PCO2 normalize, continue with target oxygen saturation of 88-92% 1
• If patient remains hypercapnic (PCO2 > 6 kPa) and acidotic (pH < 7.35) after 30 minutes of standard medical management, continue NPPV with targeted oxygen therapy 1
• Consider intubation if there is worsening of ABGs and/or pH in 1-2 hours or lack of improvement after 4 hours of NPPV 1

Contraindications for NPPV

• Respiratory arrest 1
• Cardiovascular instability (hypotension, arrhythmias, myocardial infarction) 1
• Impaired mental status, somnolence, inability to cooperate 1
• Copious and/or viscous secretions with high aspiration risk 1
• Recent facial or gastro-oesophageal surgery 1
• Craniofacial trauma and/or fixed naso-pharyngeal abnormality 1
• Burns and extreme obesity 1

Common Pitfalls to Avoid

• Excessive oxygen therapy leading to worsening hypercapnia - maintain target saturation of 88-92% 1
• Sudden cessation of supplementary oxygen which can cause life-threatening rebound hypoxemia 1
• Inadequate expiratory time for COPD patients - ensure appropriate I:E ratio (approximately 1:2) 1
• Delayed escalation to invasive ventilation when NPPV is failing - monitor closely for worsening ABGs 1