Impact of COVID-19 on the association between pulse oximetry and arterial oxygenation in patients with acute respiratory distress syndrome.

Managing patients with acute respiratory distress syndrome (ARDS) requires frequent changes in mechanical ventilator respiratory settings to optimize arterial oxygenation assessed by arterial oxygen partial pressure (PaO2) and saturation (SaO2). Pulse oxymetry (SpO2) has been suggested as a non-invasive surrogate for arterial oxygenation however its accuracy in COVID-19 patients is unknown. In this study, we aimed to investigate the influence of COVID-19 status on the association between SpO2 and arterial oxygenation. We prospectively included patients with ARDS and compared COVID-19 to non-COVID-19 patients, regarding SpO2 and concomitant arterial oxygenation (SaO2 and PaO2) measurements, and their association. Bias was defined as mean difference between SpO2 and SaO2 measurements. Occult hypoxemia was defined as a SpO2 ≥ 92% while concomitant SaO2 < 88%. Multiple linear regression models were built to account for confounders. We also assessed concordance between positive end-expiratory pressure (PEEP) trial-induced changes in SpO2 and in arterial oxygenation. We included 55 patients, among them 26 (47%) with COVID-19. Overall, SpO2 and SaO2 measurements were correlated (r = 0.70; p < 0.0001), however less so in COVID-19 than in non-COVID-19 patients (r = 0.55, p < 0.0001 vs. r = 0.84, p < 0.0001, p = 0.002 for intergroup comparison). Bias was + 1.1%, greater in COVID-19 than in non-COVID-19 patients (2.0 vs. 0.3%; p = 0.02). In multivariate analysis, bias was associated with COVID-19 status (unstandardized ß = 1.77, 95%CI = 0.38-3.15, p = 0.01), ethnic group and ARDS severity. Occult hypoxemia occurred in 5.5% of measurements (7.7% in COVID-19 patients vs. 3.4% in non-COVID-19 patients, p = 0.42). Concordance rate between PEEP trial-induced changes in SpO2 and SaO2 was 84%, however less so in COVID-19 than in non-COVID-19 patients (69% vs. 97%, respectively). Similar results were observed for PaO2 regarding correlations, bias, and concordance with SpO2 changes. In patients with ARDS, SpO2 was associated with arterial oxygenation, but COVID-19 status significantly altered this association.

Characteristics of Cardiac Injury in Critically Ill Patients With Coronavirus Disease 2019.

BACKGROUND: Cardiac injury has been reported in up to 30% of coronavirus disease 2019 (COVID-19) patients. However, cardiac injury is defined mainly by troponin elevation without description of associated structural abnormalities and its time course has not been studied. RESEARCH QUESTION: What are the ECG and echocardiographic abnormalities as well as their time course in critically ill COVID-19 patients? STUDY DESIGN AND METHODS: The cardiac function of 43 consecutive COVID-19 patients admitted to two ICUs was assessed prospectively and repeatedly, combining ECG, cardiac biomarker, and transthoracic echocardiographic analyses from ICU admission to ICU discharge or death or to a maximum follow-up of 14 days. Cardiac injury was defined by troponin elevation and newly diagnosed ECG or echocardiographic abnormalities, or both. RESULTS: At baseline, 49% of patients demonstrated a cardiac injury, and 70% of patients experienced cardiac injury within the first 14 days of ICU stay, with a median time of occurrence of 3 days (range, 0-7 days). The most frequent abnormalities were ECG or echocardiographic signs, or both, of left ventricular (LV) abnormalities (87% of patients with cardiac injury), right ventricular (RV) systolic dysfunction (47%), pericardial effusion (43%), new-onset atrial arrhythmias (33%), LV relaxation impairment (33%), and LV systolic dysfunction (13%). Between baseline and day 14, the incidence of pericardial effusion and of new-onset atrial arrhythmias increased and the incidence of ECG or echocardiographic signs, or both, of LV abnormalities as well as the incidence of LV relaxation impairment remained stable, whereas the incidence of RV and LV systolic dysfunction decreased. INTERPRETATION: Cardiac injury is common and early in critically ill COVID-19 patients. ECG or echocardiographic signs, or both, of LV abnormalities were the most frequent abnormalities, and patients with cardiac injury experienced more RV than LV systolic dysfunction.

Use of Venovenous Extracorporeal Membrane Oxygenation in Critically-Ill Patients With COVID-19.

Acute respiratory distress syndrome (ARDS) related to Coronavirus disease (COVID-19) is associated with high mortality. It has been suggested that venovenous extracorporeal membrane oxygenation (ECMO) was suitable in this indication, albeit the effects of ECMO on the mechanical respiratory parameters have been scarcely described. In this case-series, we prospectively described the use of venovenous ECMO and its effects on mechanical respiratory parameters in eleven COVID-19 patients with severe ARDS. Implantation of ECMO occurred 6 [3-11] days after the onset of mechanical ventilation. At the time of ECMO implantation, all patients received neuromuscular blocking agents, three (27%) received inhaled nitric oxide and prone positioning was performed in all patients with 4 [3-5] sessions of PP per patient. Under ECMO, the tidal volume was significantly decreased from 6.1 [4.0-6.3] to 3.4 [2.5-3.6] mL/kg of predicted body weight and the positive end-expiratory pressure level was increased by 25 ± 27% whereas the driving pressure and the mechanical power decreased by 33 ± 25% and 71 ± 27%, respectively. The PaO2/FiO2 ratio significantly increased from 68 [58-89] to 168 [137-218] and the oxygenation index significantly decreased from 28 [26-35] to 13 [10-15]. The duration of ECMO was 12 [8-25] days. Nine (82%) patients experienced ECMO-related complications and the main complication was major bleeding requiring blood transfusions. Intensive care unit mortality rate was 55% but no patient died from ECMO-related complications. In COVID-19 patients with severe ARDS, venovenous ECMO allowed ultra-protective ventilation, improved oxygenation and should be considered in highly selected patients with the most severe ARDS.

Severe metabolic acidosis after out-of-hospital cardiac arrest: risk factors and association with outcome.

BACKGROUND: Metabolic acidosis is frequently observed as a consequence of global ischemia-reperfusion after out-of-hospital cardiac arrest (OHCA). We aimed to identify risk factors and assess the impact of metabolic acidosis on outcome after OHCA. METHODS: We included all consecutive OHCA patients admitted between 2007 and 2012. Using admission data, metabolic acidosis was defined by a positive base deficit and was categorized by quartiles. Main outcome was survival at ICU discharge. Factors associated with acidosis severity and with main outcome were evaluated by linear and logistic regressions, respectively. RESULTS: A total of 826 patients (68.3% male, median age 61 years) were included in the analysis. Median base deficit was 8.8 [5.3, 13.2] mEq/l. Male gender (p = 0.002), resuscitation duration (p < 0.001), initial shockable rhythm (p < 0.001) and post-resuscitation shock (p < 0.001) were associated with an increased level of acidosis. ICU mortality rate increased across base deficit quartiles (39.1, 59.2, 76.3 and 88.3%, p for trend < 0.001), and base deficit was independently associated with ICU mortality (p < 0.001). The proportion of CPC 1 patients among ICU survivors was similar across base deficit quartiles (72.8, 67.1, 70.5 and 62.5%, p = 0.21), and 7.3% of patients with a base deficit higher than 13.2 mEq/l survived to ICU discharge with complete neurological recovery. CONCLUSION: Severe metabolic acidosis is frequent in OHCA patients and is associated with poorer outcome, in particular due to refractory shock. However, we observed that about 7% of patients with a very severe metabolic acidosis survived to ICU discharge with complete neurological recovery.