MATERIALS AND METHODS
This is an observational cohort study on all cardio-vascular consecutive patients evaluated and/or treated at Poliambulanza Foundation Hospital in Brescia (Italy) in the first 30 days of activity as a hub center. Written informed consent to participate in anonymous data collection was obtained from all patients. The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by the institution’s committee.
The Lombardia region, with its 10.6 million inhabitants, is the most populated and productive region of the north of Italy, and it was the largest affected area in Europe 11European Centre for Disease Prevention and Control https://www.ecdc.europa.eu/en/cases-2019-ncov-eueea,2.  The Lombardy RHCS decided to establish a hub and spoke network for all the major clinical and surgical pathologies across the region to face the Sars-Cov19 pandemia and to continue to assure highly specialized care. The decree issued the 08th of March 2020 by the RHCS regarding cardiovascular surgical pathologies22Lombardy Regional Council Ordinance (DGR) n° XI/2906, divided the Lombardy region into four major areas choosing for each of them a core hospital with a referral network of up to 5 cardiac surgery spoke centers and up to 10 vascular surgery spoke centers. Poliambulanza Foundation Hospital, a no-profit private hospital site in Brescia, was appointed Hub center for the cardio-vascular surgical activity to cover an area of 3.145.312 inhabitants located in the east of the region (fig. 1). Role of the Hub hospital was to guarantee 24/7 active guard on-site and at least two on-call teams for both vascular and cardiac surgery urgencies and emergencies. Meanwhile, spoke centers could free human and logistic resources to expand their capability to accept COVID patients requiring hospitalization. Regardless of public or private property, all the hospitals with cardiac or vascular surgery departments were involved in the new organization extremizing the already existing territorial hub-spoke network. Night and day shifts were organized with mixed staff coming from different centers to collaborate in the Hub surgical activity. Though spokes centers had been converted to treat patients with Covid-19 infection, some of them maintained an on-call team available on site for the management of non-transferable cases linked to Emergency Department direct admittance or emergency complications of other surgical or medical activities (transplant, trauma center, stroke, myocardial infarction etc.)5
As in war scenario, Rules of Engagement were established in a collegial remote meeting between Hub centers. Eligibility and exclusion criteria for surgery are summarized in table I. All elective surgery interventions were postponed. Not deferrable cases (class A indication according to Health Care National System recommendations)33Ministero della salute , Italia, National Plan for hospital waiting list, 2019-2021 http://www.salute. gov.it/portale/listeAttesa/dettaglioPubblicazioniListeAttesa.jsp?lingua=italiano&id=2824 (16 April 2020 last access were singularly discussed to create a co-shared waiting list between hub and spokes.
For what concern vascular diseases, the ones that deserve a non-deferrable vascular intervention were identified and inspired by the “Elective Case Triage Guidelines for Surgical Case” edited by the American College of Surgeon44American College of Surgeons. COVID-19: recommendations for management of elective surgical procedures. Available at: https://www.facs.org/about-acs/covid-19/information-for-surgeons /elective-surgery. Accessed the 19th of March, 2020 (tab. I).
All urgent and scheduled patients were preoperatively tested with a nasopharyngeal swab and/or a thorax CT scan. In case of emergency surgery, the patient was considered and treated as infected until the results of a complete screening were obtained.
A color-based triage was applied: red tag for COVID affected patients, yellow tag for patients with pending COVID test, and green tag for patient resulted negative at the swab test. Separate track and in-hospital stays were instituted to assure a safe pathway for non-COVID patients from admittance to discharge. Red, yellow, and green wards and ICU units were set up.
All preoperative and perioperative variables were collected and summarized in table III-IV-VI, including referral center and transfer time for acute peripheral ischemia. Patients who underwent evaluation but who were discarded for surgery were collected separately, signaling the reason for the exclusion.
Data entry was managed by physicians directly involved in patients’ care. Records were recorded and analyzed with Microsoft Excel (Microsoft Corp, Redmond, Wash). Continuous variables were tested for normality using the Shapiro-Wilk’s test. Variables that were normally distributed are presented as means ±standard deviation (SD) and their range; otherwise they are presented as median and interquartile range (IQR). Categorical variables are presented as frequencies and percentages. Categorical variables were analyzed using a chi-square test or Fisher’s exact test where necessary. An independent samples Student’s T-test was used for continuous variables. All reported P values are 2-sided; a P value <0.05 is considered significant.