1. Humidified High Flow Nasal Cannula (HHFNC) Oxygen therapy at Campbelltown Hospital
Julia Parmeter (Paediatric Fellow) & Nicole Cook (CNE)
With thanks to Justin Smith (CNS)

2. HHFNC Oxygen Guideline
MP4 conference in June 2014 presented data on the use of HHFNC Oxygen in NSW NETS referrals
Wide variability in usage
Developed a guidelines for MP4 units and emergency departments to provide consistent and safe clinical practice for using HHFNC in infants

3. Definition of HHFNC oxygen
A system that delivers warm, humidified gas at high flow rates that generate positive airway pressure
HHFNC oxygen is thought to act as a bridge between low flow oxygen therapies and Continuous Positive Airways Pressure (CPAP), reducing the need for intubation
High flow at 1-2 L/kg/minute generates a positive pharyngeal pressure between 4-6 cmH2O

4. How does it work Theory: 1. Humidifcation
2. Washes out oropharyngeal dead space
3. Generates positive pressure
4. Reduces energy expenditure

5. How does it work? Humidification
Humidification of the inhaled oxygen / blended air and oxygen improves mucociliary clearance
Also decreases the resistance in nasal mucosa induced by dry and cold gas, thereby improving inspiratory flow

6. How does it work? 2. High flow affects the oropharyngeal dead space
A flow higher than the patient’s inspiratory flow provides better oxygen delivery than low flow oxygen or highly concentrated oxygen with a mask
High flow washes out the end-expiratory oxygen depleted gas in the oropharyngeal dead space
In the next breath, the patient breathes in oxygen and reduces CO2 rebreathing
Infants and children have an extra-thoracic dead space 2-3 times higher than adults

7. How does it work? 3. Positive pharyngeal pressure
Positive pharyngeal pressure results in:
Prevention of pharyngeal collapse
Compensates the inspiratory burden and facilitates inspiratory flow
Prevents small airway collapse and increases expiratory time
The pressure generated depends on:
The flow rate
The prong / nostril ratio
Whether the mouth is opened or closed

8. How does it work? 4. Reduced energy expenditure
The positive pressure at the time of inspiration generates an inspiratory flow as soon as the inspiratory muscles begin working which reduces the burden on the muscles
Studies demonstrating decreased electrical activity of the diaphragm and decreased oesophageal pressure swings in infants with bronchiolitis on high flow

9. General concepts:
Increased work of breathing?  Increase the flow rate
Decreased oxygenation ?  Increase the FiO2

10. Indications for use:
Moderate to severe respiratory distress in infants (0-12 months) with bronchiolitis who have failed to respond to low flow oxygen
May have a role in moderate to severe respiratory distress in children who have failed to respond to low flow oxygen, but there is limited evidence to support this
Use for indications other than bronchiolitis may have some merit, but should only be considered after senior medical consultation and implementation of appropriate disease specific treatments

11. Contra-indications Neonates in special care nurseries
Nasal obstruction (eg choanal atresia)
Trauma (facial #, suspected base of skull #, chest wall injuries)
Life threatening hypoxia / apnoeas / haemodynamic therapy
Pneumothorax
Foreign body aspiration
Cyanotic congenital heart disease

12. Not a complete contra-indication, but proceed with caution:
Decreased level of consciousness
Congenital heart disease
Asthma *
Chronic respiratory disease

13. *Asthma and HHFNC
Physiologically, HHFNC seems an attractive option for asthmatic patients
May decrease the burden on inspiratory muscles
Heated / humidified gas may decrease the amount of bronchoconstriction induced by cold/dry gas
The high flow should theoretically improves the distribution of inhaled treatment
However, the dose of bronchodilator received varies between 0.5% to 25% of the administered dose
Limited evidence for the use of in line mesh vibration nebuliser adaptor

14. Asthma – recommendations at Campbelltown
Any child requiring metered dose or nebulised medications (eg salbutamol) during HHFNC need to have the high flow ceased or have the flow significantly reduced (<4L/min) during the time of administration
If no significant clinical improvement, cease high flow and treat the asthma

15. What do Paediatrics want to hear?
History
HPC: duration of symptoms, presence / absence of seizures
PMHx: previous hospital admissions, known medical conditions, allergies, immunisation status etc
Examination findings
Relevant investigations
NPA
Chest x-ray
Bloods
Differentials...

16. What do you need to do before starting high flow?
The most senior doctor (paediatric or emergency) should have reviewed the patient and the Paediatrician on call must have been informed and agreed to the use of HHFNC oxygen
Informed consent from the parent or carer and documented in the notes
Prescription of high flow, including the FiO2 and flow rate in L/kg/min should be documented
Flow 1L/kg/minute
FiO2 40%

17. Starting Parameters 1. Flow Commence at 1L/kg/min
Improvement defined by a reduction in heart rate by 20% (equates to a trend from red to yellow or yellow to blue ones on SPOC chart)
A decrease in respiratory rate and WOB should follow
If no improvement to WOB, heart rate and respiratory rate after 15 minutes, titrate up to 2L/kg/min to a maximum of 25 L/min
If no improvement within 60 minutes on 2L/kg/min (or max 25 L/min), the patient needs senior medical review and escalation of therapy
2. FiO2
Commence with 40% FiO2
Titrate up or down to maintain oxygen saturations between 92-98% – to a maximum of 60%
If unable to maintain saturations above 92% at a maximum of 60% FiO2 – get help

20. What is the set up? Equipment: Oxygen and air source
Oxygen blender or oxygen analyser
Flow meter 0-30 L/min
Humidified base and Humidifier circuit
Nasal cannula
Sterile 2L water bag
Nasogastric / orogastric tube

21. HHFNCO2 Set Up

23. Please refer to,
NSW Kids and Families, Humidification High-Flow
Nasal Cannula Oxygen: Standards for Metropolitan Paediatric Level 4
Units, NSW Health 2015
for more comprehensive set-up instructions.

24. Nasal Cannula Selection
As the size of nasal cannula has been demonstrated to impact on the level of CPAP in preterm infants, but has not been established in the paediatric setting, the following parameters should be utilised.
“At all times a slight visible gap should be seen between the nares and the nasal cannula”
The 2 available nasal cannulas on our ward are,
· Fisher & Paykel OPT316 (Infant) - Maximum flow of 20L/min.
· Fisher & Paykel OPT318 (Paediatric) - Maximum flow of 25L/min.
PLEASE REMEMBER: A MAXIMUM OF EITHER 20 OR 25LOF FLOW CAN BE ACHIEVED WITH OUR CURRENT EQUIPMENT

25. Ongoing care
Medical review must occur again within 1 hour of commencement of high flow therapy and 4 hourly at a minimum if patient stable at the 1 hour review
Patient should be nursed with a patient ratio of 1:2 in Close Observation Area by a registered nurse experienced and educated in paediatric nursing care
If patient remains stable after 24 hours of HHFNC therapy, ongoing medical review should occur 4-8 hourly

26. Monitoring requirements
Continuous cardio-respiratory monitoring
Continuous oxygen saturation monitoring
Hourly check and documentation of FiO2, flow and circuit
4th hourly temperature check
Blood pressure check once per nursing shift, unless abnormal
Blood glucose level 6th hourly for fasting infants

27. Other care concerns Nasogastric tube Feeding IV access
Not contra-indicated – depends on respiratory status and clinical situation
Continuous feeds vs IV fluids
IV fluids generally 2/3 maintenance
IV access
Consider need for antibiotics

28. Not improving? ? Pneumothorax ? Aspiration ? Nasal trauma
? Equipment problem
? Need to escalate therapy
? Right diagnosis
Notify Paediatrician & consider NETS consultation

29. Weaning HHFNC Oxygen When to wean: Order of weaning:
Mild or no increased work of breathing
Normal parameters (HR, RR)
Saturations >92%
Order of weaning:
Wean FiO2 by 10% increments (aiming to maintain SpO2 >92%)
Once needing less than 40% FiO2 with minimal work of breathing, decreased flow rate
First to 1L/kg/min
If child remains stable for 2-4 hours, then reduce again to 0.5 L/kg/min and then cease
If flow is under 2L/min and there is still an oxygen requirement, swap to low flow oxygen
Cease once child is in 21% O2 and <4L/min

30. Case studies from 2016

31. 1. MR
4 week old boy brought in by parents with cough and increased work of breathing, poor feeding. Day 2 of symptoms.
Antenatal history – NAD
HR 150, RR 48, Sats 95% room air, afebrile. Mild to moderate work of breathing, bilateral crackles and wheeze
Admitted to paediatric ward. Commenced on oxygen 2L via NP for work of breathing.
Gradual increase in work of breathing
NPA – RSV +

32. Observation Chart

33. Progress VBG: Commenced on HHFNC 1L /kg/minute FiO2 40% pH 7.28
pCO2 55
HCO3 26
BE -1
Lactate 2.6
Commenced on HHFNC 1L /kg/minute FiO2 40%

34. Observation Chart
High Flow Commenced

35. Progress Titrated up to 2L/kg/minute, FiO2 30% Repeat VBG: pH 7.33
pCO2 44
HCO3 26
BE -1
Lactate 1.9

36. Observation Chart
High flow ↑2L/kg/min

37. Progress Clinical improvement FiO2 weaned to 21%
Flow rate gradually weaned and ceased.
Discharged home after 3 day admission.

39. 2. AU
7 week old infant presented to ED with significant respiratory distress
3-4 days of cough and runny nose, 1 day increased work of breathing. Poor feeding
Antenatal history - NAD
On presentation to ED – RR 55, grunting, prolonged expiratory phase, HR 190 bpm, mottled and tachycardic.
Commenced 2L/min NP oxygen.
Ongoing work of breathing
NPA – RSV +

40. Commenced HHFNC 1L/kg/minute FiO2 30%
VBG:
pH 7.24
pCO2 65
HCO3 28
BE 0
Commenced HHFNC 1L/kg/minute FiO2 30%

41. Progress Admitted to Paediatric ward Titrated to 2L/kg/minute FiO2 40%
Ongoing severe WOB
VBG:
pH 7.23
pCO2 75
HCO3 28
BE 1
Transferred to SCH PICU via NETS - CPAP

42. Observation chart

44. Take-home messages Indications & contraindications for bronchiolitis
Notify Paediatrician if starting HHFNC oxygen therapy
Starting prescription:
Flow 1L/kg/min
FiO2 40%
If no improvement within 15 minutes, titrate flow and FiO2
If no improvement within 60 minutes, consider diagnosis, complications and escalation of care. NOTIFY senior medical officer
Weaning of HHFNC Oxygen:
First FiO2
Second flow
Review regularly

46. Thank you
and
good luck.