Cumulative oxygen deficit is a novel predictor for the timing of invasive mechanical ventilation in COVID-19 patients with respiratory distress

Oxygen Debt as Predictor of Mortality and Multiple Organ Dysfunction Syndrome in Severe COVID-19 Patients: A Retrospective Study

Background: Oxygen debt (DEOx) represents the disparity between resting and shock oxygen consumption (VO2) and is associated with metabolic insufficiency, acidosis, severity, and mortality. This study aimed to assess the reliability of DEOx as an indirect quantitative measure for predicting multiple organ dysfunction syndrome (MODS) and 28-day mortality in patients admitted to the intensive care unit (ICU) with respiratory syndrome severe acute coronavirus type 2 (SARS-CoV-2) infection, in comparison to the Acute Physiology and Chronic Health Evaluation II (APACHE II), sepsis-related organ failure assessment (SOFA), and 4C scores. Methods: A retrospective cohort study was conducted, including ICU patients with SARS-CoV-2 infection between 2020 and 2021. Clinical data were extracted from the EPIMED Monitor Database®. APACHE II, SOFA, and 4C scores were calculated upon ICU admission, and their accuracy in predicting 28-day mortality and MODS was compared to DEOx. Multivariate logistic regression analysis was performed to analyze the outcome variables. Results: 708 patients were included, with a mortality rate of 44.4%. DEOx value was 11.16 ml O2/kg. The mean age was 58.7 years. Multivariate analysis showed that DEOx was independently associated with mortality, intubation, and renal injury. Each point increase in creatinine was associated with a higher risk of MODS. To determine the precision of the scores, area under the receiver operating characteristic curves (AUROC) analysis was performed with weak discrimination and similar behavior for the primary outcomes. The most accurate scale for mortality and MODS was 4C with an AUC of 0.683 and APACHE II with an AUC of 0.814, while that of the AUROC of DEOx was 0.612 and 0.646, respectively. Conclusions: DEOx showed similar predictive value to established scoring systems in critically ill patients with SARS-CoV-2 infection. The correlation of DEOx with these scores may facilitate early intervention in critically ill patients.

Descriptive characteristics of continuous oximetry measurement in moderate to severe covid-19 patients

Non-invasive oxygen saturation (SpO2) is a central vital sign used to shape the management of COVID-19 patients. Yet, there have been no report quantitatively describing SpO2 dynamics and patterns in COVID-19 patients using continuous SpO2 recordings. We performed a retrospective observational analysis of the clinical information and 27 K hours of continuous SpO2 high-resolution (1 Hz) recordings of 367 critical and non-critical COVID-19 patients hospitalised at the Rambam Health Care Campus, Haifa, Israel. An absolute SpO2 threshold of 93% most efficiently discriminated between critical and non-critical patients, regardless of oxygen support. Oximetry-derived digital biomarker (OBMs) computed per 1 h monitoring window showed significant differences between groups, notably the cumulative time below 93% SpO2 (CT93). Patients with CT93 above 60% during the first hour of monitoring, were more likely to require oxygen support. Mechanical ventilation exhibited a strong effect on SpO2 dynamics by significantly reducing the frequency and depth of desaturations. OBMs related to periodicity and hypoxic burden were markedly affected, up to several hours before the initiation of the mechanical ventilation. In summary, OBMs, traditionally used in the field of sleep medicine research, are informative for continuous assessment of disease severity and response to respiratory support of hospitalised COVID-19 patients. In conclusion, OBMs may improve risk stratification and therapy management of critical care patients with respiratory impairment.

Prognostic accuracy of inflammatory markers in predicting risk of ICU admission for COVID-19: application of time-dependent receiver operating characteristic curves

Objective

Intensive care unit (ICU) admission occurs at different times during hospitalization among patients with COVID-19. We aimed to evaluate the time-dependent receive operating characteristic (ROC) curve and area under the ROC curve, AUC(t), and accuracy of baseline levels of inflammatory markers C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR) in predicting time to an ICU admission event in patients with severe COVID-19 infection.

Methods

In this observational study, we evaluated 724 patients with confirmed severe COVID-19 referred to Ayatollah Rohani Hospital, affiliated with Babol University of Medical Sciences, Iran.

Results

The AUC(t) of CRP and NLR reached 0.741 (95% confidence interval [CI]: 0.661–0.820) and 0.690 (95% CI: 0.607–0.772), respectively, in the first 3 days after hospital admission. The optimal cutoff values of CRP and NLR for stratification of ICU admission outcomes in patients with severe COVID-19 were 78 mg/L and 5.13, respectively. The risk of ICU admission was significantly greater for patients with these cutoff values (CRP hazard ratio = 2.98; 95% CI: 1.58–5.62; NLR hazard ratio = 2.90; 95% CI: 1.45–5.77).

Conclusions

Using time-dependent ROC curves, CRP and NLR values at hospital admission were important predictors of ICU admission. This approach is more efficient than using standard ROC curves.

Clinical Characteristics of COVID-19: Risk Factors for Early Oxygen Requirement after Hospitalization

BACKGROUND

Some coronavirus disease 2019 (COVID-19) patients initially present with early oxygen demand, requiring more medical resources, and some develop severe conditions, while others worsen later in their clinical course. Whether the nature of the two groups is the same but in the spectrum of different diagnostic time points is not certain.

METHODS

Hospitalized COVID-19 patients who needed oxygen therapy from February to November 2020 were included in the study. The patients were divided into early and late groups based on the time when the oxygen requirement occurred. Basic and epidemiologic characteristics were compared. Clinical variables were analyzed in both groups.

RESULTS

A total of 164 patients needed oxygen therapy, 94 of whom were in the early group and 70 of whom were in the late group. The early and late groups had similar baseline characteristics except age (median age, 73 vs. 67 years), uncertain exposure history (50% vs. 31.4%) and the time from the onset of illness to admission (median, 5 vs. 2 days). Multivariate analysis showed that age > 65 years (OR, 4.65), symptom onset > 5 days (OR, 9.13) and several clinical manifestations, such as febrile sensation (OR, 6.01), dyspnea (OR, 30.0), C-reactive protein > 1 mg/dL (OR, 7.87) and chest X-ray abnormality (OR, 8.15), were predictive factors in the early group. The early group required more intensive care such as mechanical ventilation care, extracorporeal membrane oxygenation and death (29.8% vs. 14.3%, P = 0.002).

CONCLUSION

Older age, especially > 65 years, and a delay of over 5 days from the onset of illness to admission were associated with early oxygen demand in COVID-19 patients. Interventions for earlier diagnosis of elderly people may benefit clinical outcomes.