Deciphering the explanatory potential of blood pressure variables on post-operative length of stay through hierarchical clustering: A retrospective monocentric study.

OBJECTIVE: Mean arterial pressure is widely used as the variable to monitor during anesthesia. But there are many other variables proposed to define intraoperative arterial hypotension. The goal of the present study was to search arterial pressure variables linked with prolonged postoperative length of stay (pLOS). DESIGN: Retrospective cohort study of adult patients having received general anesthesia for a scheduled non-cardiac surgical procedure between 15th July 2017 and 31st December 2019. METHODS: pLOS was defined as a stay longer than the median (main outcome), adjusted for surgery type and duration. 330 arterial pressure variables were analyzed and organized through a clustering approach. An unsupervised hierarchical aggregation method for optimal cluster determination, employing Kendall's tau coefficients and a penalized Bayes information criterion was used. Variables were ranked using the absolute standardized mean distance (aSMD) to measure their effect on pLOS. Finally, after multivariate independence analysis, the number of variables was reduced to three. RESULTS: Our study examined 9,516 patients. When LOS is defined as strictly greater than the median, 34% of patients experienced pLOS. Key arterial pressure variables linked with this definition of pLOS included the difference between the highest and lowest pulse pressure values computed throughout the surgery (aSMD[95%CI] = 0.39[0.31-0.40], p<0.001), the accumulated time pulse pressure above 61mmHg (aSMD = 0.21[0.17-0.25], p<0.001), and the lowest MAP during surgery (aSMD = 0.20[0.16-0.24], p<0.001). CONCLUSIONS: By applying a clustering approach, three arterial pressure variables were associated with pLOS. This scalable method can be applied to various dichotomized outcomes.

Lung Abscess in Critically Ill Coronavirus Disease 2019 Patients With Ventilator-Associated Pneumonia: A French Monocenter Retrospective Study.

The pulmonary vascular endothelialitis together with the high rate of distal pulmonary embolism or thrombosis extensively reported in critically ill coronavirus disease 2019 patients may impair antibiotic diffusion in the lung parenchyma of coronavirus disease 2019 patients with ventilator-associated pneumonia leading to insufficient antibiotic concentration, thus promoting lung abscess formation. We report that 17 of 119 coronavirus disease 2019 patients (14%) with ventilator-associated pneumonia developed a lung abscess. Proportion of patients receiving corticosteroids did not differ between patients with and without lung abscess. Most of lung abscess were polymicrobial. Enterobacteriaceae, Pseudomonas aeruginosa, and Staphylococcus aureus were the leading causative bacteria. Most of lung abscesses involved the right lower lobe. Three patients had concomitant pulmonary embolism or thrombosis in the territory of lung abscess. Lung abscess was retrospectively visible on chest radiograph in 29% of the patients. As the occurrence of lung abscess impacts the duration of antibiotics therapy, chest CT scan should be easily performed in case of treatment failure of ventilator-associated pneumonia despite adequate antimicrobial therapy.