Use of High-Flow Nasal Cannula in Patients With Pneumonia and Hypoxemic Respiratory Failure at Altitudes Above 2600 m: What Is the Best Predictor of Success?

Abstract

Introduction: The use of high-flow nasal cannulas (HFNC) in patients with hypoxemic ventilatory failure reduces the need for mechanical ventilation and does not increase mortality when intubation is promptly applied. The aim of the study is to describe the behavior of HFNC in patients who live at high altitudes, and the performance of predictors of success/failure of this strategy. Methods: Prospective multicenter cohort study, with patients aged over 18 years recruited for 12 months in 2020 to 21. All had a diagnosis of hypoxemic respiratory failure secondary to pneumonia, were admitted to intensive care units, and were receiving initial management with a high-flow nasal cannula. The variables assessed included need for intubation, mortality in ICU, and the validation of SaO2, respiratory rate (RR) and ROX index (IROX) as predictors of HFNC success / failure. Results: One hundred and six patients were recruited, with a mean age of 59 years and a success rate of 74.5%. Patients with treatment failure were more likely to be obese (BMI 27.2 vs 25.5; OR: 1.03; 95% CI: .95-1.1) and had higher severity scores at admission (APACHE II 12 vs 20; OR 1.15; 95% CI: 1.06-1.24). Respiratory rates after 12 (AUC .81 CI: .70-.92) and 18 h (AUC .85 CI: .72-0.90) of HFNC use were the best predictors of failure, performing better than those that included oxygenation. ICU mortality was higher in the failure group (6% vs 29%; OR 8.8; 95% CI:1.75-44.7). Conclusions: High-flow oxygen cannula therapy in patients with hypoxemic respiratory failure living at altitudes above 2600 m is associated with low rates of therapy failure and a reduced need for mechanical ventilation in the ICU. The geographical conditions and secondary physiological changes influence the performance of the traditionally validated predictors of therapy success. Respiratory rate <30 proved to be the best indicator of early success of the device at 12 h of use.

The ROX index as a predictor of high-flow nasal cannula outcome in pneumonia patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis

“…After deduplication and excluding irrelevant citations, we reviewed the full text of the remaining 58 records carefully. Finally, thirteen studies [10,12,13,[21][22][23][24][25][26][27][28][29][30] were deemed as eligible and included in this meta-analysis. The PRISMA flowchart of study inclusion is presented in Fig.…”

“…Among the 13 included studies, six [10,12,13,21,29,30] were prospectively designed and 7 [22][23][24][25][26][27][28] were retrospectively designed, and 10 [12, 21-28, 30] recruited AHRF patients with COVID-19-associated pneumonia. The sample size ranged from 30 to 324.…”

“…The durations of HFNC application were largely different among the included studies, which ranged from 16.2 h to 3 days in the failure group and from 41.5 to 242 h in the success group. Nine studies [10,12,13,21,24,25,27,29,30] explicitly defined the criteria to diagnose AHRF or indicate HFNC application. Of note, the criteria for suggesting HFNC application in one study [12] did not fulfill the criteria to diagnose AHRF in our study.…”

“…The remaining 4 studies [22,23,26,28] did not report the definition of AHRF. Ten studies [12,[21][22][23][24][25][26][27][28]30] reported the ROX index with available diagnostic accuracy that measured within 6 h after the HFNC onset, and seven studies [10,13,22,23,26,29,30] reported the ROX index with available diagnostic accuracy that measured during 6-12 h after the HFNC onset. Details on the baseline characteristics and the diagnostic accuracy are presented in Table 1 and Additional file 2: Tables S2 and S3.…”

High-flow nasal cannula oxygen reduced hypoxemia in patients undergoing gastroscopy under general anesthesia at ultra-high altitude: a randomized controlled trial

“…A recent study conducted at 2600-m altitude reported 75% success (as defined by not requiring invasive mechanical ventilation) with HFNC treatment in ICU patients with hypoxemic respiratory failure [ 24 ]. Results of the current study added much-needed support for the benefits of HFNC in managing patients in high-altitude areas.…”