Conservative management of COVID-19 associated hypoxaemia

Abstract

Background: Invasive mechanical ventilation of hypoxaemic coronavirus disease 2019 (COVID-19) patients is associated with mortality rates of >50%. We evaluated clinical outcome data of two hospitals that agreed on a predefined protocol for restrictive use of invasive ventilation where the decision to intubate was based on the clinical presentation and oxygen content rather than on the degree of hypoxaemia.

Method: Data analysis was carried out of patients with positive PCR-testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), typical history, and symptoms and pulmonary infiltrates who exhibited oxygen saturation values of <93%.

Results: We identified 78 patients who met the inclusion criteria. The oxygen saturation nadir was 84.4±6.5% for the whole group. 53 patients (68%) received nasal oxygen (group 1), 17 patients (22%) were treated with nasal high-flow continuous positive airway pressure (CPAP), noninvasive ventilation or a combination thereof (group 2), and eight patients (10%) were intubated (group 3). The Horovitz index was 216±8 for group 1, 157±13 for group 2 and 106±15 for group 3. Oxygen content was 14.5±2.5, 13.4±1.9 and 11.6±2.6 mL O₂·dL^-1 for the three respective groups. Overall mortality was 7.7%; the mortality of intubated patients was 50%. Overall, 93% of patients could be discharged on room air.

Conclusion: Permissive hypoxaemia where decisions for the level of respiratory therapy were based on the clinical presentation and oxygen content resulted in low intubation rates, low overall mortality and a low number of patients who require oxygen after discharge.

FIGURE 1

Escalation sequence. CPAP: continuous positive airway pressure.

FIGURE 2

Distribution of the highest level of respiratory support that was delivered to the patient. NHF: nasal high-flow; CPAP: continuous positive airway pressure; NIV: noninvasive ventilation.

FIGURE 3

Oxygen saturation nadir of the respective treatment groups. The thick line in the middle is the median. The top and bottom box lines show the first and third quartiles. The whiskers show the maximum and minimum values, with the exceptions of outliers (circles) and extremes (asterisks). Outliers are at least 1.5 box lengths from the median and extremes are at least three box lengths from the median. The case numbers are given for outliers and extremes. NHF: nasal high-flow; CPAP: continuous positive airway pressure; NIV: noninvasive ventilation.

FIGURE 4

Lowest reported Horovitz index (arterial oxygen tension/inspiratory oxygen fraction ratio) of the respective treatment groups. The thick line in the middle is the median. The top and bottom box lines show the first and third quartiles. The whiskers show the maximum and minimum values, with the exceptions of outliers (circles). Outliers are at least 1.5 box lengths from the median. The case numbers are given for outliers. NHF: nasal high-flow; CPAP: continuous positive airway pressure; NIV: noninvasive ventilation.

FIGURE 5

Lowes measured arterial oxygen content (C_aO2) of the respective treatment groups. NHF: nasal high-flow; CPAP: continuous positive airway pressure; NIV: noninvasive ventilation.

FIGURE 6

Outcome/respiratory support at discharge according to the maximal respiratory support received. NHF: nasal high-flow; CPAP: continuous positive airway pressure; NIV: noninvasive ventilation.