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

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

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

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

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

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

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

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

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

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

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

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

*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

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

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...

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%

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

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

HHFNCO2 Set Up

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.

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

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

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

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

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

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

Case studies from 2016

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 +

Observation Chart

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%

Observation Chart High Flow Commenced

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

Observation Chart High flow ↑2L/kg/min

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

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 +

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

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

Observation chart

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

Thank you and good luck.