This document provides information on non-invasive ventilation (NIV) including: 1. The physiologic effects of positive pressure ventilation such as increased laminar flow and alveolar recruitment. 2. Contraindications and types of respiratory failure and their management approaches. BiPAP is used for hypercapnic failure with acidosis while CPAP is used for acute hypoxia. 3. Guidelines for setting pressures on CPAP and BiPAP and troubleshooting persistent hypoxia or hypercapnia by adjusting pressures. 4. Early predictors of NIV failure including a pH <7.3 and lack of acute worsening of chronic respiratory failure. 5. Clinical vignettes describing

1. NIV: indications, settings, and that
pesky order form
Ryan Cheng

2. Physiologic Pathway Of Positive Pressure
Ventilation
1
• Positive pressure ventilation
2
• Increased laminar flow
3
• Airway stenting
• Atelectatic alveoli recruitment
4
• Increased functional residual capacity
• Increase in tidal volume, resulting in increased minute ventilation
5
• Increased intrathoracic pressure
6
• Decreased venous return
• Increased left heart output

4. Contraindications
Absolute Relative
Need for immediate endotracheal intubation Decreased level of consciousness
High risk of vomiting and aspiration Hemodynamic instability
Past facial surgery precluding proper mask fit Severe hypoxia and/or hypercapnia, PaO2/FiO2 ratio
of < 200 mm Hg
PaCO2 < 60 mm Hg
Poor patient cooperation
Lack of trained or experienced staff

5. Types Of Respiratory Failure And Their
Management Approaches
Type of Respiratory Failure Examples Management Approach
Hypoxic (inadequate oxygenation) • Pneumonia
• Congestive heart failure
• Interstitial respiratory disease
• Increase fraction of inspired
oxygen
• Increase mean airway pressure
• Increase peak end-expiratory
pressure
Hypercarbic (inadequate
ventilation)
• Chronic obstructive pulmonary
disease
• Increase respiratory rate
• Increase tidal volume

6. BiPAP vs CPAP
• CPAP: inspiratory = expiratory pressure (constant)
• Acute hypoxia
• BiPAP: inspiratory > expiratory pressure
• Hypercapnic respiratory failure with acidosis

7. Pressure Settings
• CPAP: start at 10cm H2O
• BiPAP: IPAP of 10cm H2O and EPAP of 5cm H2O
• IPAP > 20cm H2O poorly tolerated and can cause gastric insufflation
• Pressures should never exceed 25cm

8. • Spontaneous
• Spontaneous with timed
mandatory
• Timed
Nursing stuff

9. Troubleshooting
• Persistent ↑CO2
• ↑ IPAP: obesity, poor compliance
• Increase by 2cm increments
• Keep EPAP unchanged while increasing IPAP to increase tidal volume
• Persistent ↓O2 despite ↓CO2
• ↑FiO2
• ↑EPAP
• Increase by 1cm increments
• IPAP must be increased simultaneously to maintain tidal volume
• Sudden deterioration
• Consider alternatives: pneumo, PE, arrhythmias…

10. Early Predictors of NIV Failure
1. Respiratory failure that is not acute-on-chronic
2. Acidosis with pH <7.3
3. Severe hypoxemia after 1hr on NIV
Pacilli AM, Valentini I, Carbonara P, et al. Determinants of noninvasive ventilation outcomes during an episode of acute hypercapnic respiratory failure in chronic obstructive
pulmonary disease: the effects of comorbidities and causes of respiratory failure. Biomed Res Int. 2014;2014:976783. (Prospective; 176 patients)

11. Clinical Vignettes
• 50yo male with COPD with 1/7 worsening SOB
• T 38.3*C RR 50 HR 130 BP 110/50 O2 sat 85%
• ABG
• pH 7.2
• PaO2 150
• PaCO2 70
• ABG 2
• pH 7.15
• PaO2 66
• PaCO2 89
Worsening PaCO2 despite therapy
Consider raising IPAP alone

12. Clinical Vignettes
• 71yo female with COPD with 3/7 productive cough
• T 37.8*C RR 25 HR 107 BP 130/80 O2 sat 88%
• ABG
• pH 7.37
• PaO2 120
• PaCO2 62
NIV not as useful when pH > 7.35. Correct the
underlying disease process.
NIV single use equipment = $3000. That’s 100
CRPs! Imagine how annoyed Richie would be!

13. Clinical Vignettes
• 81yo male with IHD, CCF, AF
• T 36.3*C RR 40 HR 120 BP 170/90 O2 sat 80%
• ABG
• pH 7.29
• PaO2 42
• PaCO2 38
• ABG 2
• pH 7.31
• PaO2 37
• PaCO2 36
Low PaO2 in isolation
Worsening despite CPAP
Consider increasing pressure by 1-2mmHg , titrate to effect