1. Respiratory Failure-When to Use
HFNC and/or BiPAP
Steven Podnos MD

2. Three Types of Respiratory Failure
• Definition: Inadequate Gas Exchange
• Three types:
• Inability to Oxygenate
• Inability to Ventilate
• Inability to Protect Airway-never candidates
for noninvasive ventilation!

3. Inability to Oxygenate
• Implies that alveoli are not exchanging gases-usually
hypoxemia. Can be V/Q mismatch or true shunt
• Alveoli are filled with fluid-CHF, Non Cardiogenic Pulm
Edema (ARDS), infected fluid (pneumonia)
• Rx O2 to keep sat 90% or better
• If unable to maintain sats with face mask/Nasal cannula-
need HFNC, positive pressure like BiPAP or intubation
• Usually increased work of breathing-patients may tire and
develop hypercapnia (high pCO2)
• Rx underlying condition: diurese CHF, supportive for
ARDS, antibiotics for infection

4. Inability to Ventilate
• Abnormalities in lung (or external) mechanics. Hallmark is hypercapnia. Elevated pCO2 displaces O2, but
hypoxemia easy to treat. May be intrinsic to lung (COPD), or extrinsic (OD, neuromuscular disease)
• Alveoli are “OK” in general
• Common causes of type II (hypercapnic) respiratory failure
• Chronic bronchitis and emphysema (COPD)
• Severe asthma
• Drug overdose
• Poisonings
• Myasthenia gravis
• Polyneuropathy
• Poliomyelitis
• Primary muscle disorders
• Porphyria
• Cervical cordotomy
• Head and cervical cord injury
• Primary alveolar hypoventilation
• Obesity hypoventilation syndrome
• Pulmonary edema
• Adult respiratory distress syndrome
• Myxedema
• Tetanus
• (note overlap with failure to oxygenate)

5. Treatment of Respiratory Failure:
• Airway
• Oxygenation
• Aerosol bronchodilators
• Diuretics
• Antibiotics
• Supportive Rx for Hypercapnia is Positive Pressure
Ventilation (external or with ETT)
• Steroids for bronchospasm
• DVT, GI bleed prophylaxis
• O2 toxicity-including risk of worsening hypercapnia

6. Monitoring of Treatment
• RR, HR
• O2 sat
• ABG mostly useful for pCO2, acid-base status
• Mental Status

7. HFNC

8. High Flow Nasal Cannula
• In infants, high flow Nasal Cannula appears to have
some positive pressure benefit and may be equivalent
to Nasal CPAP in efficacy
• In Adults, allows higher concentration of inspired
oxygen than a traditional nasal cannula. Flows at
35L/min appear to provide low levels of positive
pressure (CPAP), especially with a closed mouth.

9. HFNC or BiPAP in Adults
• If the patient requires positive pressure
ventilation, choose BiPAP.
• If they patient primarily requires a high level
of inspired oxygen (CHF, ARDS without
fatigue), then HFNC may be adequate

11. Non Invasive Ventilation
• Using positive pressure ventilation without an
endotracheal tube
• Used for Obstructive Sleep Apnea, Respiratory
Support of various illnesses to prevent
intubation

12. CPAP
• Continuous Positive Airway Pressure-usually a
set level pressure-same with inspiration and
expiration. Note that Expiratory Pressure is
the same thing as PEEP (Positive End
Expiratory Pressure). Normal PEEP is zero!

13. BiPAP vs. CPAP
• Individually set Inspiratory and Expiratory
Pressures. Can also adjust timing of I/E
• Indicated for difficulty with Oxygenation
(EPAP/PEEP) and/or Respiratory muscle
support (IPAP)
• Contraindications: Risk of
Aspiration, Agitation, Poor cough, lack of
cooperation

14. Indications
• Suitable clinical conditions for noninvasive ventilation (most patients)
Chronic obstructive pulmonary disease
• Cardiogenic pulmonary edema
• Suitable clinical conditions for noninvasive ventilation (selected patients)
After discontinuation of mechanical ventilation (COPD)
• Community-acquired pneumonia (and COPD)
• Asthma
• Immunocompromised state
• Postoperative respiratory distress and respiratory failure
• Do-not-intubate status
• Neuromuscular respiratory failure
• Decompensated obstructive sleep apnea/cor pulmonale
• Cystic fibrosis
• Acute respiratory distress syndrome

15. Advantages of BiPAP
• May reverse impending respiratory failure and
avoid intubation
• Reduced risk of nosocomial pneumonia
• Buys time while reversing hypercapnia and
cardiogenic pulmonary edeama

16. Disadvantages of BiPAP
• Complications of noninvasive ventilation
• Facial and nasal pressure injury and sores
– Result of tight mask seals used to attain adequate inspiratory volumes
– Minimize pressure by intermittent application of noninvasive ventilation
– Schedule breaks (30-90 min) to minimize effects of mask pressure
– Balance strap tension to minimize mask leaks without excessive mask pressures
– Cover vulnerable areas (erythematous points of contact) with protective dressings
• Gastric distension
– Rarely a problem
– Avoid by limiting peak inspiratory pressures to less than 25 cm water
– Nasogastric tubes can be placed but can worsen leaks from the mask
– Nasogastric tube also bypasses the lower esophageal sphincter and permits reflux
• Dry mucous membranes and thick secretions
– Seen in patients with extended use of noninvasive ventilation
– Provide humidification for noninvasive ventilation devices
– Provide daily oral care
• Aspiration of gastric contents
– Especially if emesis during noninvasive ventilation
– Avoid noninvasive ventilation in patient with ongoing emesis or hematemesis
• Complications of both noninvasive and invasive ventilation
Barotrauma (significantly less risk with noninvasive ventilation)
• Hypotension related to positive intrathoracic pressure (support with fluids)

17. BiPAP Settings
• Typically begin with 10cm Inspiratory and 5cm
Expiratory Pressures. Adjust as needed for
support and hypoxemia.
• Remember, EPAP = PEEP
• PEEP paradoxically can help with both Shunt
and Obstructive Disease

18. Use in COPD

19. Monitoring BiPAP
• Look at Patient-HR, RR, BP
• Increasing pCO2 a bad sign
• Worsening Hypoxemia a bad sign

20. Weaning BiPAP
• May slowly reduce both inspiratory and
expiratory pressures
• May alternatively just switch to simple
supplemental Oxygen

21. Conclusions
• Three types of Respiratory Failure
• Non-invasive ventilatory support is usually
worth considering
• HFNC is oxygenation support only
• BiPAP is both ventilatory and oxygenation
support