High Flow Oxygen Therapy at Two Initial Flow Settings versus Conventional Oxygen Therapy in Cardiac Surgery Patients with Postextubation Hypoxemia: A Single-Center, Unblinded, Randomized, Controlled Trial

Abstract

In cardiac surgery patients with pre-extubation PaO2/inspired oxygen fraction (FiO2) < 200 mmHg, the possible benefits and optimal level of high-flow nasal cannula (HFNC) support are still unclear; therefore, we compared HFNC support with an initial gas flow of 60 or 40 L/min and conventional oxygen therapy. Ninety nine patients were randomly allocated (respective ratio: 1:1:1) to I = intervention group 1 (HFNC initial flow = 60 L/min, FiO2 = 0.6), intervention group 2 (HFNC initial flow = 40 L/min, FiO2 = 0.6), or control group (Venturi mask, FiO2 = 0.6). The primary outcome was occurrence of treatment failure. The baseline characteristics were similar. The hazard for treatment failure was lower in intervention group 1 vs. control (hazard ratio (HR): 0.11, 95% CI: 0.03–0.34) and intervention group 2 vs. control (HR: 0.30, 95% CI: 0.12–0.77). During follow-up, the probability of peripheral oxygen saturation (SpO2) > 92% and respiratory rate within 12–20 breaths/min was 2.4–3.9 times higher in intervention group 1 vs. the other 2 groups. There was no difference in PaO2/FiO2, patient comfort, intensive care unit or hospital stay, or clinical course complications or adverse events. In hypoxemic cardiac surgery patients, postextubation HFNC with an initial gas flow of 60 or 40 L/min resulted in less frequent treatment failure vs. conventional therapy. The results in terms of SpO2/respiratory rate targets favored an initial HFNC flow of 60 L/min.

The effects of flow settings during high-flow nasal cannula support for adult subjects: a systematic review

“…One hundred and forty-eight full-text articles were assessed for eligibility, and 44 studies were finally included, of which 11 were in vitro studies [ 26 , 28 – 37 ], 2 combined in vitro and in vivo studies to investigate patients with AHRF [ 6 , 14 ], 13 studies investigated healthy individuals [ 13 , 15 – 20 , 38 – 43 ], 9 investigated patients with AHRF [ 7 – 10 , 27 , 44 – 46 , 50 ], 5 studies examined patients with COPD [ 11 , 12 , 21 – 23 ], 1 study investigated both AHRF and COPD patients [ 24 ], and 3 investigated patients during procedural sedation [ 47 – 49 ]. Among the in vivo studies, only four were randomized controlled trials [ 27 , 47 – 49 ], while 18 were randomized crossover studies [ 7 , 8 , 10 , 12 , 13 , 16 , 17 , 22 – 24 , 38 , 40 – 43 , 45 , 46 , 50 ]. None of the included randomized trials had incomplete outcome data reporting but 10 did not have registration [ 7 , 8 , 10 , 13 , 41 , 43 , 46 , 48 – 50 ].…”

“…During HFNC oxygen therapy, flow settings have been shown to have a significant impact on short-term clinical outcomes in 32 studies [ 6 – 24 , 38 – 50 ] and long-term outcomes in one study [ 27 ].…”

“…HFNC washes out upper airway dead space, and its effects are maximized when the delivered gas flow meets or exceeds the patient peak inspiratory flow, resulting in a stable fraction of inspired oxygen (F I O 2 ) and a level of positive end-expiratory pressure (PEEP) [ 6 , 26 ]. Thus, flow settings play a vital role during HFNC oxygen therapy [ 27 ].…”

The short-term efficacy of high flow nasal oxygen therapy on cardiovascular surgical patients: a randomized crossover trial

“…The most distinctive characteristic of this study is that we directly measured the flow rate of VM by using the HALOSCALE® flowmeter when comparing the rate with HFNC. As for those studies [ 5 , 6 ] using HFNC compared with VM, the method application of VM was not mentioned in detail. VM cannot provide pre-set oxygen concentration with inappropriate total flow rate of < 30 L/min.…”

Comparison of high-flow nasal cannula and conventional oxygen therapy for high-risk patients during bronchoscopy examination: protocol for a randomized controlled trial

“…Because of its ability to provide high gas ow to exceed the inspiratory ow demand of patients, there is little or no need to obtain oxygen from the air, and thus F I O 2 is constant during HFNC treatment [2,3]; moreover, the high ow also generates positive endexpiratory pressure [1,4]. Therefore, HFNC has been proven to be superior to conventional oxygen therapy (COT) in improving oxygenation and avoiding intubation in hypoxemic patients [5][6][7][8][9][10][11][12][13][14][15]. Additionally, HFNC is also shown to reduce hypercapnia and improve ventilation in patients with chronic obstructive pulmonary disease (COPD) [16][17][18][19][20][21], since high ow gas washes out the dead space [19][20][21].…”