Dead space ventilation-related indices: bedside tools to evaluate the ventilation and perfusion relationship in patients with acute respiratory distress syndrome.

Cumulative evidence has demonstrated that the ventilatory ratio closely correlates with mortality in acute respiratory distress syndrome (ARDS), and a primary feature in coronavirus disease 2019 (COVID-19)-ARDS is increased dead space that has been reported recently. Thus, new attention has been given to this group of dead space ventilation-related indices, such as physiological dead space fraction, ventilatory ratio, and end-tidal-to-arterial PCO2 ratio, which, albeit distinctive, are all global indices with which to assess the relationship between ventilation and perfusion. These parameters have already been applied to positive end expiratory pressure titration, prediction of responses to the prone position and the field of extracorporeal life support for patients suffering from ARDS. Dead space ventilation-related indices remain hampered by several deflects; notwithstanding, for this catastrophic syndrome, they may facilitate better stratifications and identifications of subphenotypes, thereby providing therapy tailored to individual needs.

Efficacy of proning in acute respiratory distress syndrome on extracorporeal membrane oxygenation.

Objectives: Proning patients with acute respiratory distress syndrome (ARDS) has been associated with increased survival, although few data exist evaluating the safety and feasibility of proning patients with ARDS on extracorporeal membrane oxygenation (ECMO). Methods: A single-institution retrospective review of all patients with ARDS placed on ECMO between March 1 and May 31, 2020, was performed. All proning events were evaluated for complications, as well as change in compliance, sweep, oxygenation, and flow. The primary outcome of this study was the rate major morbidity associated with proning while on ECMO. Results: In total, 30 patients were placed on ECMO for ARDS, with 12 patients (40%) proned while on ECMO. A total of 83 proning episodes occurred, with a median of 7 per patient (interquartile range, 3-9). No ECMO cannula-associated bleeding, cannula displacement, or endotracheal tune dislodgements occurred (0%). Oropharyngeal bleeding occurred twice (50%). Four patients were proned with chest tubes in place, and none had complications (0%). Lung compliance improved after proning in 70 events (84%), from a mean of 15.4 mL/mm Hg preproning to 20.6 mL/mm Hg postproning (P < .0001). Sweep requirement decreased in 36 events (43%). Oxygenation improved in 63 events (76%), from a mean partial pressure of oxygen of 86 preproning to 103 postproning (P < .0001). Mean ECMO flow was unchanged. Conclusions: Proning in patients with ARDS on ECMO is safe with an associated improvement in lung mechanics. With careful planning and coordination, these data support the practice of appropriately proning patients with severe ARDS, even if they are on ECMO.

Evaluation of the effect of hyperchloremia on the prognosis and mortality of medical intensive care patients: a single-center study.

BACKGROUND: While chloride (Cl) is the most abundant anion in the serum, it is unfortunately one of the most commonly disregarded laboratory test results routinely drawn upon admission into the medical intensive care unit (MICU). We aimed to investigate the relation between in-hospital mortality, different pathologies requiring admission to the MICU, serum Cl levels, and other biochemical tests in a tertiary center. METHODS: The prospective study included data from 373 patients admitted to the ICU of a tertiary care center between 2017 and 2019. Data of patients under 18, pregnant patients or patients who were in the MICU for under 48 h were excluded. Comorbidity status, complete blood count, biochemistry tests, and blood gas analysis results of all patients included in the study were collected and recorded. Univariate and multivariate analyses were performed with the obtained data. RESULTS: : Of the patients included in the study, 158 (42.4%) were discharged, and 215 (57.6%) died. In the receiver operator characteristics curve analysis performed to determine the discriminating power of Cl levels with a cut-off value of >98 mEq/L in relation to mortality, its sensitivity was found to be 84% and specificity 60%. According to Kaplan-Meier analysis results, mortality rate was higher (60% vs 46%) and survival time was lower (19.0 ± 1.46 vs. 23.0 ± 4.36 days; p = 0.035) in the patient group with high Cl levels compared to the patient group with normal or low Cl levels. In the Cox regression analysis, it was found that the survival time of the patients hospitalized in the MICU was associated with the variables of Cl, presence of cancer diagnosis and pCO2 (hazard ratio: 1.030 (1.008-1.049), 2.260(1.451-3.500), and 1.020 (1.003-1.029); p < 0.05, respectively). DISCUSSION: Mortality in MICU patients were found to increase in association with higher Cl levels at admission, presence of cancer disease, and higher pCO2 levels. In addition, it should not be ignored that there may be an important relationship between renal failure and hyperchloremia in MICU patients.

COVID-19 Smell Impairment and Crosstalk with Hypoxia Physiology.

Since its apomorphic appearance in 2019, severe acute respiratory syndrome Coronavirus type 2 (SARS-CoV-2) nowadays circulates as a plesiomorphic human virus in several synapomorphic variants. The respiratory tract is the most important site of infection, the viral effects in the lungs are well described, and more than half of the patients could develop shortness of breath and dyspnea and require ventilatory support. The physiological sign of this condition is the decrease in the partial pressure of oxygen in the blood, leading to acute hypoxia, which could be a factor in the disease. In severe patients, we recorded several physiological parameters: breath frequency (BF), partial pressure of oxygen in the blood (pO2), partial pressure of carbon dioxide in the blood (pCO2), hemoglobin (Hb), heart rate (HR), and blood pressure in correlation with the olfactory threshold. We found significant correlations between reduced olfactory threshold with pO2 and hemoglobin levels, changes in heart rate, and increased HR and pCO2. These results suggest that COVID-19 causes an impaired sense of smell that decreases in threshold corresponding to the disease severity.