High Flow Nasal Cannula Oxygen HFNC. Dr I S Kalla Department of Pulmonology University of the Witwatersrand

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1 786 High Flow Nasal Cannula Oxygen HFNC Dr I S Kalla Department of Pulmonology University of the Witwatersrand

2 Disclaimer I was a scep@c un@l I used it Now I am a firm believer

3 HFNC The Fisher and Paykel system: Passover humidifier, a high performance circuit and Op@flowTM nasal cannula Device draws inspiratory gas through a chamber in which water is being simultaneously evaporated by a hea@ng plate Delivers up to 50 L/min of gas which is heated and humidified to 37 C and humidified to 44 mg/l. The Vapotherm : Device uses membrane transfer technology to generate a high flow of warm humidified gas Gas can be delivered via nasal cannula at flows 5 40 L/min and at temperatures of C(Celsius) allowing for a rela@ve humidity (RH) of 100% to be

4 HFNC flushing of expired air from the upper airway during flushing of upper airway dead space improves efficiency reduces the work of breathing generates a posi@ve end-expiratory (PEEP) may counterbalance auto- PEEP Spole&ni CHEST 2015; 148 ( 1 ):

5 HFNC High-flow nasal cannula (HFNC) delivers a flows rate up to 8 L/min in infants and 60 L/min in adults The device consists of an air/oxygen blender connected through an ac@ve heated humidifier to the nasal cannula and allows adjustment of the FiO2 independently from the flow rate HFNC first used in preterm neonates and pediatric care and currently being evaluated as a first-line treatment in respiratory distress syndrome, in apnea of prematurity, and in the post-extuba@on period to prevent extuba@on failure Manley BJ Neonatology ; 102 ( 4 ):

6 HFNC PEEP: generated directly to the gas flow delivered: the higher the flow, the higher the pressure. The large nasal cannulae could create a certain degree of nasal obstruc@on while the con@nuously delivered high flow causes resistance during expira@on, thereby genera@ng posi@ve pressure. BUT this PEEP effect is markedly reduced when the pa@ent opens his/her mouth. PEEP level only moderate, helps to improve gas exchange and decrease the work of breathing in pa@ents with intrinsic PEEP Washout of dead space: induced by high gas flow rate con@nuously delivered in the airways may generate a washout of flushing carbon dioxide out of the upper airways helps to improve the efficiency of ven@la@on and to reduce the work of breathing HFNC oxygen is delivered through nasal cannulae, reducing dead space and making rebreathing less likely By contrast, a reservoir mask delivering standard oxygen or a facial mask for NIV is a supplemental dead space that may promote rebreathing of carbon dioxide

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8 Groves & Tobin. Australian Care (2007) 20,

9 Spole&ni CHEST 2015; 148 ( 1 ):

10 HFNC FIO2 delivered can reach up to 100% when using NIV in the absence of leaks Maximal FIO2 does not exceed 70% with standard oxygen despite a reservoir mask and a flow rate up to 15 L/min Inspiratory flow rate generated by a pa@ent suffering from ARF reaches at least L/min on average, and can even exceed 60 L/min in more severe pa@ents Oxygen is consequently mixed with room air, reducing FIO2 delivered to the pa@ent In a physiological study, measured FIO2 in healthy subjects ven@lated using a standard mask, a non-rebreathing mask with a reservoir and HFNC oxygen: Standard mask flow rate of 12 L/min - FIO2 was <60% and dropped to <50% when they simulated ARF HFNC oxygen flow rate of 40 L/min - FIO2 reached 85% This effect could directly contribute to improvement in oxygena@on and to the decrease in the respiratory rate observed when switching from standard oxygen to HFNC oxygen

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12 Spole&ni CHEST 2015; 148 ( 1 ):

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20 A total of 310 were included in the analyses rate (primary outcome) was 38% (40 of 106 in the high-flow oxygen group, 47% (44 of 94) in the standard group, and 50% (55 of 110) in the group (P = 0.18 for all comparisons) Ven@lator-free days at day 28 was significantly higher in the high-flow oxygen group (24±8 days, vs. 22±10 in the standard-oxygen group and 19±12 in the noninvasive-ven@la@on group; P = 0.02 for all comparisons) The hazard ra@o for death at 90 days was 2.01 (95% confidence interval [CI], 1.01 to 3.99) with standard oxygen versus high-flow oxygen (P = 0.046) and 2.50 (95% CI, 1.31 to 4.78) with noninvasive ven@la@on versus high-flow oxygen (P = 0.006).

21 Among the 115 analyzed, 60 (52 %) were treated with HFNC alone and 55 (48 %) with NIV as firstline therapy with 30 (55 %) receiving HFNC and 25 (45 %) standard oxygen between NIV sessions. The rates of and 28-day mortality were higher in treated with NIV than with HFNC (55 vs. 35 %, p = 0.04, and 40 vs. 20 %, p = 0.02 log-rank test, respec@vely) Using propensity score-matched analysis, NIV was associated with mortality Using mul@variate analysis, NIV was independently associated with intuba@on and mortality.

22 HFNC oxygen therapy seems to be a real technological innova@on Well tolerated, easy to use and improves gas exchange without the poten@al deleterious effects of mechanical ven@la@on Physiological effects include high FIO2 delivery, PEEP effect and washout of dead space of the airways Several large RCTs suggest beneficial effects in pa@ents with ARF or in the postextuba@on period However, its use should not delay intuba@on if respiratory criteria for reintuba@on are met or in the case of other dysfunc@on, especially shock or neurological failure