Too much tolerance for hyperoxemia in mechanically ventilated patients with SARS-CoV-2 pneumonia? Report from an Italian intensive care unit

Elisa Damiani; Erika Casarotta; Andrea Carsetti; Giulia Mariotti; Sara Vannicola; Rachele Giorgetti; Roberta Domizi; Claudia Scorcella; Erica Adrario; Abele Donati

doi:10.3389/fmed.2022.957773

Too much tolerance for hyperoxemia in mechanically ventilated patients with SARS-CoV-2 pneumonia? Report from an Italian intensive care unit

Front Med (Lausanne). 2022 Jul 28:9:957773. doi: 10.3389/fmed.2022.957773. eCollection 2022.

Authors

Elisa Damiani^{1

2}, Erika Casarotta¹, Andrea Carsetti^{1

2}, Giulia Mariotti¹, Sara Vannicola², Rachele Giorgetti¹, Roberta Domizi², Claudia Scorcella², Erica Adrario^{1

2}, Abele Donati^{1

2}

Affiliations

¹ Department of Biomedical Sciences and Public Health, Università Politecnica delle Marche, Ancona, Italy.
² Anesthesia and Intensive Care Unit, Azienda Ospedaliera Universitaria "Ospedali Riuniti Umberto I-Lancisi-Salesi", Ancona, Italy.

Abstract

Background: In COVID-19 patients requiring mechanical ventilation, the administration of high oxygen (O₂) doses for prolonged time periods may be necessary. Although life-saving in most cases, O₂ may exert deleterious effects if administered in excessive concentrations. We aimed to describe the prevalence of hyperoxemia and excessive O₂ administration in mechanically ventilated patients with SARS-CoV-2 pneumonia and determine whether hyperoxemia is associated with mortality in the Intensive Care Unit (ICU) or the onset of ventilator-associated pneumonia (VAP).

Materials and methods: Retrospective single-center study on adult patients with SARS-CoV-2 pneumonia requiring invasive mechanical ventilation for ≥48 h. Patients undergoing extracorporeal respiratory support were excluded. We calculated the excess O₂ administered based on the ideal arterial O₂ tension (PaO₂) target of 55-80 mmHg. We defined hyperoxemia as PaO₂ > 100 mmHg and hyperoxia + hyperoxemia as an inspired O₂ fraction (FiO₂) > 60% + PaO₂ > 100 mmHg. Risk factors for ICU-mortality and VAP were assessed through multivariate analyses.

Results: One hundred thirty-four patients were included. For each day of mechanical ventilation, each patient received a median excess O₂ of 1,121 [829-1,449] L. Hyperoxemia was found in 38 [27-55]% of arterial blood gases, hyperoxia + hyperoxemia in 11 [5-18]% of cases. The FiO₂ was not reduced in 69 [62-76]% of cases of hyperoxemia. Adjustments were made more frequently with higher PaO₂ or initial FiO₂ levels. ICU-mortality was 32%. VAP was diagnosed in 48.5% of patients. Hyperoxemia (OR 1.300 95% CI [1.097-1.542]), time of exposure to hyperoxemia (OR 2.758 [1.406-5.411]), hyperoxia + hyperoxemia (OR 1.144 [1.008-1.298]), and daily excess O₂ (OR 1.003 [1.001-1.005]) were associated with higher risk for ICU-mortality, independently of age, Sequential Organ failure Assessment score at ICU-admission and mean PaO₂/FiO₂. Hyperoxemia (OR 1.033 [1.006-1.061]), time of exposure to hyperoxemia (OR 1.108 [1.018-1.206]), hyperoxia + hyperoxemia (OR 1.038 [1.003-1.075]), and daily excess O₂ (OR 1.001 [1.000-1.001]) were identified as risk factors for VAP, independently of body mass index, blood transfusions, days of neuromuscular blocking agents (before VAP), prolonged prone positioning and mean PaO₂/FiO₂ before VAP.

Conclusion: Excess O₂ administration and hyperoxemia were common in mechanically ventilated patients with SARS-CoV-2 pneumonia. The exposure to hyperoxemia may be associated with ICU-mortality and greater risk for VAP.

Keywords: ARDS; COVID-19; SARS-CoV-2; hyperoxia; oxygen; ventilator-associated pneumonia.