What are the overall settings for a BiPAP (Bilevel Positive Airway Pressure) machine?

BiPAP Machine Settings: A Comprehensive Guide

BiPAP (Bilevel Positive Airway Pressure) machines require specific pressure, timing, and mode settings that should be adjusted based on the patient's underlying respiratory condition and clinical response to optimize ventilation and reduce morbidity and mortality.

Core Pressure Settings

• IPAP (Inspiratory Positive Airway Pressure):

  • Initial setting: 16-18 cmH2O for type 2 respiratory failure 1
  • Range: 8-30 cmH2O for adults, 8-20 cmH2O for children <12 years 1
  • Adjust in 1-2 cmH2O increments at intervals no shorter than 5 minutes 2

• EPAP (Expiratory Positive Airway Pressure):

  • Initial setting: 6-8 cmH2O 1
  • Maintains airway patency and prevents alveolar collapse 1
  • Typically 4-10 cmH2O lower than IPAP 1

• Pressure Support (PS = IPAP - EPAP):

  • Target: 10 cmH2O for significant respiratory acidosis 1
  • Range: 4-10 cmH2O 1
  • Increase PS if tidal volume is low (<6-8 mL/kg) or if PCO2 remains elevated 1

Mode Settings

• Spontaneous (S) Mode:

  • Patient triggers both inspiration and expiration
  • Used for patients with stable respiratory drive

• Spontaneous/Timed (ST) Mode:

  • Recommended for most patients, especially those with:
    • Central hypoventilation
    • Significant central apneas
    • Inappropriately low respiratory rate
    • Muscle weakness affecting reliable triggering 2, 1

• Timed (T) Mode:

  • Fixed respiratory rate with no patient triggering
  • Consider if ST mode is unsuccessful 2
  • Rarely used in most sleep centers 2

Respiratory Rate Settings (for ST and T modes)

• Backup Rate:
  • Initial setting: Equal to or slightly less than patient's spontaneous sleeping respiratory rate (minimum 10 breaths/min) 2
  • If sleeping rate unknown, use spontaneous awake respiratory rate 2
  • Increase in increments of 1-2 breaths if ventilation remains inadequate 2, 1

Timing Settings

• Inspiratory Time (IPAP time):

  • Initial setting: Based on respiratory rate and I:E ratio 2
  • Recommended %IPAP time: 30-40% of cycle time 2
  • Default: Often 1.2 seconds 2
  • Shorter inspiratory time (%IPAP ~30%): Better for obstructive airways disease 2
  • Longer inspiratory time (%IPAP ~40%): Better for restrictive disease 2

• I:E Ratio (Inspiratory:Expiratory ratio):

  • Minimum recommended: 1:2 2
  • Longer exhalation recommended for obstructive lung disease 2
  • Calculated as IPAP time / EPAP time 2

Oxygen Settings

• Target SpO2: 88-92% for type 2 respiratory failure 1
  • Avoid exceeding 92% to prevent worsening hypercapnia 1
  • Adjust FiO2 as needed to maintain target range 1

Adjustment Algorithm for Respiratory Events

1. For obstructive apneas:

   • Increase both IPAP and EPAP by ≥1 cmH2O if ≥2 apneas in adults or ≥1 in children <12 years 1

2. For hypopneas:

   • Increase IPAP by ≥1 cmH2O if ≥3 hypopneas in adults or ≥1 in children <12 years 1

3. For RERAs (Respiratory Effort-Related Arousals):

   • Increase IPAP by ≥1 cmH2O if ≥5 RERAs in adults or ≥3 in children <12 years 1

4. For snoring:

   • Increase IPAP by ≥1 cmH2O if ≥3 minutes of loud snoring in adults or ≥1 minute in children <12 years 1

5. For persistent hypercapnia:

   • Increase PS by 1-2 cmH2O if PCO2 remains ≥10 mmHg above goal for ≥10 minutes 2, 1

Monitoring and Optimization

• Allow at least 30 minutes without respiratory events before considering settings optimized 1
• Exploration of pressure above the level that controls respiratory events should not exceed 5 cmH2O 1
• Reassess with arterial blood gas after 1 hour to evaluate response 1
• Monitor continuously for:
  • SpO2
  • Respiratory rate
  • Work of breathing
  • Patient comfort
  • Mask leaks 1

Troubleshooting Common Issues

• Patient discomfort with high pressure:

  • Reduce IPAP by 1-2 cmH2O to improve tolerance 1
  • Adjust to a comfortable level that allows return to sleep 2

• Significant mask leaks:

  • Perform mask refit or change mask type 1
  • Consider oronasal mask or chin strap if mouth leak occurs 1

• Nasal/pharyngeal dryness or irritation:

  • Add heated humidification 1

Relationship Between Key Parameters

Respiratory Rate (breaths/min)	Cycle Time (sec)	30% IPAP time (sec)	40% IPAP time (sec)
10	6	1.8	2.4
12	5	1.5	2.0
15	4	1.2	1.6
20	3	0.9	1.2

Table adapted from American Academy of Sleep Medicine guidelines 2

By following these evidence-based settings and adjustment protocols, BiPAP therapy can be optimized to improve ventilation, reduce work of breathing, and ultimately decrease morbidity and mortality in patients requiring non-invasive ventilatory support.