High Flow Nasal Cannula: Physiological Effects and Clinical Applications

Contents
1: Conventional Oxygen Therapy: Technical and Physiological Issues
	1.1	 Introduction
	1.2	 Conventional Oxygen Therapy
		1.2.1	 Historical Overview of Oxygen Discovery and Utilization
		1.2.2	 Updated Recommendations for Oxygen Utilization
	1.3	 Physiological Effects of Oxygen and Toxicity
		1.3.1	 Physiological Role of Oxygen and Cellular Toxicity
		1.3.2	 Oxygen Is a Dangerous Gas!
		1.3.3	 Risks Associated with Hypoxemia
		1.3.4	 Risks Associated with Hyperoxia: Oxygen Toxicity (Fig. 1.4)
			1.3.4.1	 Direct Oxygen Lung Toxicity
			1.3.4.2	 Importance of Accurate Titration of Oxygen Flow Rates in COPD Patients
			1.3.4.3	 Vascular Risks Associated with Hyperoxia Are Now Well Demonstrated
			1.3.4.4	 Neurological Toxicity
			1.3.4.5	 Oxygen Toxicity in Perioperative and Critical Care Patients
			1.3.4.6	 Oxygen Toxicity in Premature Infants
	1.4	 Technical Aspects of Oxygen Delivery
		1.4.1	 Oxygen Sources
		1.4.2	 Humidification
		1.4.3	 Interfaces to Deliver Low-Flow Oxygen
		1.4.4	 Estimation of FiO2 Delivered in Spontaneously Breathing Patients
		1.4.5	 Monitoring of Conventional Oxygen Therapy
	1.5	 Devices Available to Deliver Oxygen in Spontaneously Breathing Patients
		1.5.1	 Innovations in Oxygen Delivery
			1.5.1.1	 Automated Adjustment of Oxygen Therapy
			1.5.1.2	 Clinical Evaluations Conducted with FreeO2 (Automated Oxygen Titration)
			1.5.1.3	 Other Systems Allowing Automatic Adjustment of Oxygen
	1.6	 Conclusion
	References
2: High-Flow Nasal Cannula: Technical Aspects in Adults and Children
	2.1	 Components of High-Flow Nasal Cannula Delivery System
		2.1.1	 Gas Flow and FiO2 Delivery
		2.1.2	 Humidification
		2.1.3	 Inspiratory Tubing
		2.1.4	 Nasal Cannula Interface
	2.2	 Commercially Available HFNC Devices
	2.3	 Contraindications and Adverse Events
		2.3.1	 Contraindications
		2.3.2	 Adverse Events
	2.4	 Initiation, Maintenance, and Weaning
		2.4.1	 Setting for HFNC Delivery and Staffing
			2.4.1.1	 Adult Considerations
			2.4.1.2	 Paediatric Considerations
		2.4.2	 Initiation and Maintenance of HFNC Therapy
		2.4.3	 Monitoring during HFNC
		2.4.4	 Weaning
		2.4.5	 Predictors of Treatment Failure
		2.4.6	 Patient Compliance with HFNC Therapy
	2.5	 Nursing Care Considerations
		2.5.1	 Skin Care and Oral Hygiene during HFNC Therapy
		2.5.2	 Activities of Daily Living
		2.5.3	 Documentation
	2.6	 Conclusion
	References
3: Physiological Effects of High Flow in Adults
	3.1	 Introduction
	3.2	 Physiological Effects in Healthy Subjects
	3.3	 Physiological Effects in Hypoxemic Patients
		3.3.1	 Positive Airway Pressure and Increase in End-Expiratory Lung Volume
		3.3.2	 Reduction in Work of Breathing
	3.4	 Physiological Effects in Chronic Patients
		3.4.1	 Improved Mucociliary Clearance, Positive Airway Pressure, and Increase in End-Expiratory Lung Volume
		3.4.2	 Reduction in Work of Breathing
	3.5	 Conclusions
	References
4: Clinical Applications of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure
	4.1	 Introduction
	4.2	 Patients with Acute Hypoxemic Respiratory Failure
	4.3	 How to Predict Outcome of HFNC
	4.4	 Patients Admitted in the ED for Acute Respiratory Failure
	4.5	 Immunocompromised Patients with Acute Respiratory Failure
	4.6	 NIV for Preoxygenation of Hypoxemic Patients
	4.7	 Remaining Questions
	4.8	 Conclusion
	References
5: Clinical Applications of High-Flow Nasal Cannula during Intubation and Weaning from Mechanical Ventilation
	5.1	 Introduction
	5.2	 Clinical Application of HFNC during Intubation
		5.2.1	 HFNC during Intubation Process in Surgical Patients
		5.2.2	 HFNC Clinical Application during Intubation Process in Critically Ill Patients
	5.3	 Clinical Application of HFNC during Weaning from Mechanical Ventilation
		5.3.1	 Pathophysiology of Weaning Failure and Weaning Management
		5.3.2	 HFNC Clinical Application during Weaning Process in Surgical Patients
		5.3.3	 HFNC Application during Weaning Process in Critically Ill Patients
	5.4	 Conclusion
	References
6: Clinical Applications of High-Flow Nasal Cannula in the Operating Room
	6.1	 During Intubation Procedure
	6.2	 Procedures without Intubation
	References
7: Clinical Applications of High-Flow Nasal Cannula in Obstructive Lung Diseases
	7.1	 Introduction
	7.2	 Physiological Mechanisms and Rationale for the Use of HFNT
		7.2.1	 Effects on Mucociliary Clearance
		7.2.2	 Effects on Dead Space
		7.2.3	 Effects on Work of Breathing
	7.3	 Potential Clinical Applications
		7.3.1	 Stable COPD
			7.3.1.1	 Effects on Quality of Life (QoL)
			7.3.1.2	 Effects on Exacerbations
			7.3.1.3	 Effects on Gas Exchange
			7.3.1.4	 Other Outcomes
		7.3.2	 Acute Exacerbations of COPD
		7.3.3	 Other Obstructive Lung Diseases
	7.4	 Conclusion
	References
8: Clinical Applications of High-Flow Nasal Cannula in Pulmonary Rehabilitation
	8.1	 Pathophysiology of Exercise Limitation
	8.2	 Mechanism of Action of High-Flow Nasal Cannula on Exercise Limitation
	8.3	 Clinical Studies
	8.4	 Conclusions and Future Applications
	References
9: Clinical Applications of High-Flow Nasal Cannula in Particular Settings: Invasive Procedures, Palliative Care and Transplantation
	9.1	 Invasive Procedures
	9.2	 Gastrointestinal Endoscopies
	9.3	 Bronchoscopy
	9.4	 Other Procedures
	9.5	 Palliative Care
	9.6	 Transplantation
	References
10: Physiological Effects and Clinical Applications of High-Flow Nasal Cannula in Children
	10.1	 Introduction
	10.2	 Definitions of Pediatric Acute Respiratory Failure [ARF]
	10.3	 Pediatric Physiological Studies
	10.4	 Outcome Pediatric Studies
	10.5	 Conclusions
	References
11: Future Perspectives
	11.1	 Introduction
	11.2	 How Should HFNC be Used?
	11.3	 Specific AHRF Etiologies
	11.4	 Predictors of HFNC Failure
	11.5	 HFNC in Sepsis
	11.6	 Conclusions
	References