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One ventilator for two patients: feasibility and considerations of a last resort solution in case of equipment shortage
  1. Tommaso Tonetti1,
  2. Alberto Zanella2,3,
  3. Giacinto Pizzilli4,
  4. Charlene Irvin Babcock5,
  5. Sergio Venturi6,
  6. Stefano Nava7,
  7. Antonio Pesenti2,3,
  8. V Marco Ranieri1
  1. 1 Department of Medical and Surgical Sciences (DIMEC), Anesthesia and Intensive Care Medicine, Sant'Orsola-Malpighi Hospital, Alma Mater Studiorum University of Bologna, Bologna, Emilia-Romagna, Italy
  2. 2 Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Lombardia, Italy
  3. 3 Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ospedale Maggiore Policlinico Mangiagalli e Regina Elena, Milano, Italy
  4. 4 Anesthesia and Intensive Care Medicine, Sant'Orsola Malpighi Hospital, Bologna, Italy
  5. 5 Department of Emergency Medicine, Ascension St John Hospital and Medical Center, Detroit, Michigan, USA
  6. 6 Covid-19 Commissioner, Emilia-Romagna Region, Bologna, Emilia-Romagna, Italy
  7. 7 Department of Clinical, Integrated and Experimental Medicine (DIMES), Respiratory and Critical Care Unit, Sant'Orsola-Malpighi Hospital, Alma Mater Studiorum University of Bologna, Bologna, Italy
  1. Correspondence to Professor V Marco Ranieri; m.ranieri{at}

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The present emergency caused by the spread of the COVID-19 infection is putting enormous pressure on the healthcare systems worldwide and especially on intensive care units (ICUs).

One of the main fears in this regard is that we may run out of ventilators, a possibility which is getting more and more likely as the pandemic spreads throughout the world and the ICUs are overloaded with ventilated patients.

Many authors have already investigated the possibility of manipulating a ventilator circuit in order to ventilate up to four patients with a single machine. Neyman and Ervin first performed a bench study demonstrating the technical feasibility of ventilating four patients with one ventilator and one modified circuit.1 The same circuit configuration was used in 2008 by Paladino et al in an animal model, resulting in substantial differences in oxygenation and decarboxylation between subjects during the ventilation period.2 In 2012 Branson et al tested in vitro the Neyman and Ervin system simulating different conditions of compliance and resistance between the simultaneously ventilated test lungs. They observed wide variability in measured tidal volume (Vt) and end-expiratory lung volume, so they concluded that the technique should be avoided because of potential danger.3 Accordingly, the authors argued that the stockpiling of ventilators should be the first-line solution when massive emergencies are forecast; only after their depletion, strategies such as the ‘double circuit’ should be implemented for the shortest possible duration.4 5

On 20 February 2020, the first case of COVID-19 emerged in the Lombardy region, northern Italy. As of 17 March, a total of 1069 patients had been admitted …

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