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.

Stavros Theologou,Christos Charitos,Spyros D Mentzelopoulos,Eleni Ischaki,Nektaria Michopanou,Stratos Patsatzis,Spyros G Zakynthinos

doi:10.3390/jcm10102079

Stavros Theologou, Christos Charitos + Show 5 more

Open Access

https://doi.org/10.3390/jcm10102079

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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.

Highlights

The high-flow nasal cannula (HFNC) delivers an inspired oxygen fraction (FiO2 ) of0.21 to 1.0 with a gas flow rate of ≤ 60 L/min [1,2]
In a more recent meta-analysis, a subgroup analysis of solely cardiac surgery studies failed to confirm any benefit of HFNC with a gas flow of 35–50 L/min [18]; the authors suggested that cardiac surgery increases the risk of postoperative pulmonary complications, and “patients may not benefit from HFNC” [18]
There was no significant difference between intervention groups 1 and 2 (HR: 0.35, 95% confidence interval (CI): 0.10–1.26; p = 0.11)

Summary

Introduction

The high-flow nasal cannula (HFNC) delivers an inspired oxygen fraction (FiO2 ) of0.21 to 1.0 with a gas flow rate of ≤ 60 L/min [1,2]. Possible HFNC-associated complications include nasal bleeding and mucus dryness, with occasional poor patient tolerance of the device [15,16]. A meta-analysis of 4 randomized clinical trials (RCTs) of HFNC vs conventional oxygen therapy after cardiothoracic surgery reported HFNC-associated reductions in the frequency of escalation of respiratory support and pulmonary complications, no differences in reintubation rate or length of intensive care unit (ICU) and hospital stay [17]. In a more recent meta-analysis, a subgroup analysis of solely cardiac surgery studies failed to confirm any benefit of HFNC with a gas flow of 35–50 L/min [18]; the authors suggested that cardiac surgery increases the risk of postoperative pulmonary complications, and “patients may not benefit from HFNC” [18]

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Conclusion