What is an appropriate BiPAP (Bilevel Positive Airway Pressure) setting for a patient with Chronic Obstructive Pulmonary Disease (COPD)?

BiPAP Settings for COPD Patients

For COPD patients requiring BiPAP, start with IPAP 8-12 cm H₂O and EPAP 4 cm H₂O in spontaneous-timed (ST) mode with a backup rate of 10-12 breaths/minute, maintaining an inspiratory time that achieves an I:E ratio of approximately 1:2 to allow adequate expiratory time and prevent air trapping. 1, 2

Initial Pressure Settings

• Begin with IPAP 8 cm H₂O and EPAP 4 cm H₂O as the standard starting point 1, 2
• For the specific setting of 20/10 mentioned in your question, this represents IPAP 20 cm H₂O and EPAP 10 cm H₂O, which is a relatively high pressure differential of 10 cm H₂O 2
• The American Academy of Sleep Medicine recommends maintaining a minimum pressure differential of 4 cm H₂O between IPAP and EPAP 2
• Maximum pressure differential should not exceed 10 cm H₂O, meaning 20/10 is at the upper limit of recommended settings 2

Mode Selection and Timing Parameters

• Use spontaneous-timed (ST) mode for COPD patients, which provides a backup rate when the patient's respiratory drive is inadequate 1, 3
• Set the backup respiratory rate at 10-12 breaths/minute, equal to or slightly less than the patient's spontaneous sleeping respiratory rate 3, 1
• Configure inspiratory time to achieve an I:E ratio of approximately 1:2 (or %IPAP time of 30%) to allow adequate expiratory time 3, 1
• A shorter inspiratory time is critical in COPD because these patients have obstructive airways disease requiring sufficient time for exhalation to prevent auto-PEEP 3

Titration Algorithm

• Increase IPAP by 1-2 cm H₂O increments every 5 minutes minimum based on tidal volume, respiratory rate, and blood gas improvement 1, 2
• Target a tidal volume of 6-8 mL/kg ideal body weight 1
• Continue titration until pH normalizes (>7.35) and PaCO₂ decreases 1
• The maximum IPAP limit is 30 cm H₂O for adults 1, 2

Clinical Context for 20/10 Settings

The setting of BiPAP 20/10 would be appropriate in the following scenarios:

• Severe hypercapnic respiratory failure where lower pressures have failed to adequately reduce PaCO₂ 1
• Patients requiring maximal pressure support while still maintaining the recommended I:E ratio 3
• After titration from lower initial settings when arterial blood gases demonstrate persistent respiratory acidosis 1

However, research evidence suggests caution with high BiPAP settings in COPD:

• One study found that BiPAP can increase work of breathing in spontaneously breathing COPD patients due to higher intrinsic PEEP (PEEPi) 4
• The higher the EPAP (10 cm H₂O in this case), the greater the risk of air trapping and increased PEEPi in COPD patients with prolonged expiratory times 4

Oxygen Supplementation

• Target SpO₂ 88-92% for COPD patients with chronic type 2 respiratory failure 1
• Start supplemental oxygen at 1 L/min and increase by 1 L/min every 15 minutes until target is achieved 1
• Add oxygen via a T-connector between the device outlet and circuit 1

Critical Monitoring Parameters

• Monitor pH, PaCO₂, respiratory rate, work of breathing, and mental status within 1-2 hours of initiating BiPAP 1
• Inability to maintain SpO₂ >90% despite FiO₂ escalation indicates BiPAP failure requiring intubation 1, 2
• In one study, pH values measured after 45 minutes of BiPAP differentiated success (pH 7.38) from failure (pH 7.28) patients 5

Evidence for Mortality Benefit

• BiPAP decreases mortality (RR 0.63,95% CI 0.46-0.87) and intubation need (RR 0.41,95% CI 0.33-0.52) for COPD exacerbations with respiratory acidosis 1
• BiPAP reduces nosocomial pneumonia (OR 0.26,95% CI 0.08-0.81) 1
• One study showed BiPAP reduced intubation rates from 71% to 26% compared to standard therapy 5

Common Pitfalls and How to Avoid Them

• Do not delay intubation if the patient deteriorates or fails to improve within 1-2 hours 1
• Maintain adequate expiratory time (I:E ratio 1:2) to prevent air trapping and auto-PEEP, which is particularly problematic at higher EPAP settings like 10 cm H₂O 3, 1
• If the patient awakens complaining that pressure is too high, restart at a lower pressure comfortable enough to allow return to sleep 1, 2
• Contraindications include: patient not spontaneously breathing, inability to protect airway, patient not oriented or unable to tolerate mask, and hemodynamic instability 1
• Be aware that approximately 29% of COPD patients do not tolerate BiPAP under acute circumstances 6

Specific Considerations for 20/10 Settings

• This represents a pressure support of 10 cm H₂O (IPAP minus EPAP), which is at the maximum recommended differential 2
• The EPAP of 10 cm H₂O is relatively high and may increase work of breathing in some COPD patients due to increased PEEPi 4
• Consider whether a lower EPAP (4-6 cm H₂O) with adjusted IPAP might achieve similar ventilation with less risk of air trapping 3
• Settings this high should only be used after titration from lower initial settings and with close monitoring of patient comfort and blood gases 1, 2