Background Use of high positive end-expiratory pressure (PEEP) and prone positioning is common in patients with COVID-19-induced acute respiratory failure. Few data clarify the hemodynamic effects of these interventions in this specific condition. We performed a physiologic study to assess the hemodynamic effects of PEEP and prone position during COVID-19 respiratory failure. Methods Nine adult patients mechanically ventilated due to COVID-19 infection and fulfilling moderate-to-severe ARDS criteria were studied. Respiratory mechanics, gas exchange, cardiac output, oxygen consumption, systemic and pulmonary pressures were recorded through pulmonary arterial catheterization at PEEP of 15 and 5 cmH 2 O, and after prone positioning. Recruitability was assessed through the recruitment-to-inflation ratio. Results High PEEP improved PaO 2 /FiO 2 ratio in all patients (p = 0.004), and significantly decreased pulmonary shunt fraction (p = 0.012), regardless of lung recruitability. PEEP-induced increases in PaO2/FiO2 changes were strictly correlated with shunt fraction reduction (rho=-0.82, p = 0.01). From low to high PEEP, cardiac output decreased by 18 % (p = 0.05) and central venous pressure increased by 17 % (p = 0.015). As compared to supine position with low PEEP, prone positioning significantly decreased pulmonary shunt fraction (p = 0.03), increased PaO 2 /FiO 2 (p = 0.03) and mixed venous oxygen saturation (p = 0.016), without affecting cardiac output. PaO 2 /FiO 2 was improved by prone position also when compared to high PEEP (p = 0.03). Conclusions In patients with moderate-to-severe ARDS due to COVID-19, PEEP and prone position improve arterial oxygenation. Changes in cardiac output contribute to the effects of PEEP but not of prone position, which appears the most effective intervention to improve oxygenation with no hemodynamic side effects.
Introduction Serum lactate dehydrogenase (LDH) levels are often elevated in cardiovascular diseases. Their prognostic role after subarachnoid hemorrhage (SAH) remains poorly evaluated. Methods This is a retrospective single-center study of patients with non-traumatic SAH admitted to the intensive care unit (ICU) of an University Hospital from 2007 to 2022. Exclusion criteria were pregnancy and incomplete medical records or follow-up data. Baseline information, clinical data, radiologic data, the occurrence of neurological complications as well as serum LDH levels during the first 14 days of ICU stay were collected. Unfavorable neurological outcome (UO) at 3 months was defined as a Glasgow Outcome Scale of 1–3. Results Five hundred and forty-seven patients were included; median serum LDH values on admission and the highest LDH values during the ICU stay were 192 [160–230] IU/L and 263 [202–351] IU/L, respectively. The highest LDH value was recorded after a median of 4 [2–10] days after ICU admission. LDH levels on admission were significantly higher in patients with UO. When compared with patients with favorable outcome (FO), patients with UO had higher serum LDH values over time. In the multivariate logistic regression model, the highest LDH value over the ICU stay (OR 1.004 [95% CI 1.002 – 1.006]) was independently associated with the occurrence of UO; the area under the receiving operator (AUROC) curve for the highest LDH value over the ICU stay showed a moderate accuracy to predict UO (AUC 0.76 [95% CI 0.72–0.80]; p < 0.001), with an optimal threshold of > 272 IU/L (69% sensitivity and 74% specificity). Conclusions The results in this study suggest that high serum LDH levels are associated with the occurrence of UO in SAH patients. As a readily and available biomarker, serum LDH levels should be evaluated to help with the prognostication of SAH patients.
The importance of non-invasive evaluation of cardiac function in diabetes is well known and radionuclide angiocardiography has become an accepted diagnostic procedure. While the pathophysiological interpretation of systolic parameters is clear, the meaning and determinants of peak filling rate (PFR) remain rather speculative. In the present study, a “pattern recognition” approach, including principal component analysis and hierarchical cluster analysis, has been adopted in order to evaluate the determinants of PFR in a series of 48 non-selected diabetic patients. The results of the study show that: PFR is inversely dependent on age which is its main determinant when systolic function is preserved; PFR is inversely dependent on combined effects of left ventricular dimensions, angina and wall motion; and the duration of diabetes in itself does not influence PFR. These results lead to the following clinically relevant conclusions:(a) It is unlikely that a young diabetic patient without anginal symptoms will have a significant PFR impairment even if the diabetes has been present for a long time. If such impairment is however present, ventricular latent dysfunction is likely to be the cause even if systolic parameters are still normal;(b) A decrease of PFR in a middle-aged diabetic patient without symptoms and with normal systolic function cannot be equated with latent ventricular dysfunction as it may represent only an age-related physiological change without special diagnostic meaning.
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