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Observational Study
. 2024 Jul 1:36:e20240203en.
doi: 10.62675/2965-2774.20240203-en. eCollection 2024.

The respiratory oxygenation index for identifying the risk of orotracheal intubation in COVID-19 patients receiving high-flow nasal cannula oxygen

[Article in English, Portuguese]
Aline Braz Pereira  1 , Felipe Dal Pizzol  2 , Viviane Cordeiro Veiga  3 , Leandro Utino Taniguchi  4 , Aline Finoti Misquita  3 , Gustavo Augusto Couto Carvalho  3 , Ligia Maria Coscrato Junqueira Silva  3 , Michelli Marcela Dadam  5 , Ruthy Perotto Fernandes  1 , Israel Silva Maia  6 , Cassio Luis Zandonai  6 , Alexandre Biasi Cavalcanti  7 , Marcelo Luz Pereira Romano  7 , Glauco Adrieno Westphal  1
Affiliations
Observational Study

The respiratory oxygenation index for identifying the risk of orotracheal intubation in COVID-19 patients receiving high-flow nasal cannula oxygen

[Article in English, Portuguese]
Aline Braz Pereira et al. Crit Care Sci. .

Abstract
in English, Portuguese

Objective: To assess whether the respiratory oxygenation index (ROX index) measured after the start of high-flow nasal cannula oxygen therapy can help identify the need for intubation in patients with acute respiratory failure due to coronavirus disease 2019.

Methods: This retrospective, observational, multicenter study was conducted at the intensive care units of six Brazilian hospitals from March to December 2020. The primary outcome was the need for intubation up to 7 days after starting the high-flow nasal cannula.

Results: A total of 444 patients were included in the study, and 261 (58.7%) were subjected to intubation. An analysis of the area under the receiver operating characteristic curve (AUROC) showed that the ability to discriminate between successful and failed high-flow nasal cannula oxygen therapy within 7 days was greater for the ROX index measured at 24 hours (AUROC 0.80; 95%CI 0.76 - 0.84). The median interval between high-flow nasal cannula initiation and intubation was 24 hours (24 - 72), and the most accurate predictor of intubation obtained before 24 hours was the ROX index measured at 12 hours (AUROC 0.75; 95%CI 0.70 - 0.79). Kaplan-Meier curves revealed a greater probability of intubation within 7 days in patients with a ROX index ≤ 5.54 at 12 hours (hazard ratio 3.07; 95%CI 2.24 - 4.20) and ≤ 5.96 at 24 hours (hazard ratio 5.15; 95%CI 3.65 - 7.27).

Conclusion: The ROX index can aid in the early identification of patients with acute respiratory failure due to COVID-19 who will progress to the failure of high-flow nasal cannula supportive therapy and the need for intubation.

Objetivo:: Avaliar se o índice de oxigenação respiratória medido após o início da terapia de oxigênio com cânula nasal de alto fluxo pode ajudar a identificar a necessidade de intubação em pacientes com insuficiência respiratória aguda devido à COVID-19.

Métodos:: Este estudo retrospectivo, observacional e multicêntrico foi realizado nas unidades de terapia intensiva de seis hospitais brasileiros, de março a dezembro de 2020. O desfecho primário foi a necessidade de intubação até 7 dias após o início da cânula nasal de alto fluxo.

Resultados:: O estudo incluiu 444 pacientes; 261 (58,7%) foram submetidos à intubação. Uma análise da área sob a curva receiver operating characteristic (ASC ROC) mostrou que a capacidade de discriminar entre o sucesso e o fracasso da oxigenoterapia com cânula nasal de alto fluxo dentro de 7 dias foi maior para o índice de oxigenação respiratória medido em 24 horas (ASC ROC 0,80; IC95% 0,76 - 0,84). O intervalo médio entre o início da cânula nasal de alto fluxo e a intubação foi de 24 horas (24 - 72), e o preditor mais preciso de intubação obtido antes de 24 horas foi o índice de oxigenação respiratória medido em 12 horas (ASC ROC 0,75; IC95% 0,70 - 0,79). As curvas de Kaplan-Meier revelaram maior probabilidade de intubação em 7 dias em pacientes com índice de oxigenação respiratória ≤ 5,54 em 12 horas (razão de risco 3,07; IC95% 2,24 - 4,20) e ≤ 5,96 em 24 horas (razão de risco 5,15; IC95% 3,65 - 7,27).

Conclusões:: O índice de oxigenação respiratória pode ajudar na identificação precoce de pacientes com insuficiência respiratória aguda devido à COVID-19 que evoluirão para o fracasso da terapia de suporte com cânula nasal de alto fluxo e a necessidade de intubação.

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Conflict of interest statement

Conflicts of interest: None.

Figures

Figure 1
Figure 1. Patients selection.
Figure 2
Figure 2. Area under the receiver operating characteristic curve and 95% confidence intervals for respiratory oxygenation index measurements at different time intervals from the start of high-flow nasal cannula therapy (baseline, 2, 4, 6, 12 and 24 hours) and its association with orotracheal intubation within 7 days.
Figure 3
Figure 3. Kaplan-Meier curves.
Figura 1
Figura 1. Seleção dos pacientes.
Figura 2
Figura 2. Área sob a curva receiver operating characteristic e intervalos de confiança de 95% para medições do índice de oxigenação respiratória em diferentes intervalos de tempo do início da terapia com cânula nasal de alto fluxo (início da terapia, 2, 4, 6, 12 e 24 horas) e sua associação com a intubação orotraqueal em 7 dias.
Figura 3
Figura 3. Curvas de Kaplan-Meier.
See this image and copyright information in PMC

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