Central venous-to-arterial carbon dioxide tension in critically ill COVID-19 patients

ABSTRACT

Introduction: Critically ill patients with coronavirus disease 2019 (COVID-19) may present severe tissue perfusion abnormalities. The mixed venous-to-arterial carbon dioxide tension difference ( PvaCO2) is an easily derived parameter identifying insufficient tissue perfusion. The purpose of this study was to evaluate the clinical relevance of high values of PvaCO2 in COVID - 19 patients early after their admission to intensive care unit (ICU). We speculated that high PvaCO2 values might be associated with poor outcome in critically ill COVID-19 patients. Methods: This was a retrospective study conducted in two independent centers of Belgium. We included patients treated in the first wave of the national outbreak with available PvaCO2 within 3 days of admission and without severe hypercapnia ( PCO2 > 75 mmHg). The highest value was registered. Normal values were considered ≤ 6 mmHg, moderate elevations 7 - 9 mmHg, and high elevations > 9 mmHg. The primary outcome was ICU discharge alive and secondary outcome mortality at 28 days. Results: Seventy-three patients were included with median age of 60 years (IQR 52 to 68), and simplified acute physiology score II (SAPS II) 26.1 (IQR 19.8 to 29.5). Fifty-three (76%) patients needed invasive ventilation within 24 h after ICU admission (12 h (IQR 12 to 24). The worst ratio of partial pressure arterial oxygen to the fraction of inspired oxygen ( PaO2/FiO2) within 3 days after admission was 151 (IQR 86 to 243) and PvaCO2 6 mmHg (IQR 5 to 9). PvaCO2 > 9 mmHg was associated with longer ICU stay (ICU free days 0 days (0 - 0) vs 1 day (0 - 18), p = 0.02), independently of PaO2/FiO2 and SAPS II score (HR 0.21, 95% - CI 0.05 - 0.92, p = 0.04) (Fig. 1, Panel A), but not to 28 days mortality (HR1.71, 95% - CI 0.48 - 5.91, p = 0.41) (Fig. 1, Panel B). Conclusions: In COVID-19 patients, high PvaCO2 values early after ICU admission are associated with prolonged ICU stay independently of hypoxemia and disease severity. (Figure Presented).