Lung-Dependent Areas Collapse, Monitored by Electrical Impedance Tomography, May Predict the Oxygenation Response to Prone Ventilation in COVID-19 Acute Respiratory Distress Syndrome.

OBJECTIVES: ICUs have had to deal with a large number of patients with acute respiratory distress syndrome COVID-19, a significant number of whom received prone ventilation, which is a substantial consumer of care time. The selection of patients that we have to ventilate in prone position seems interesting. We evaluate the correlation between the percentage of collapsed dependent lung areas in the supine position, monitoring by electrical impedance tomography and the oxygenation response (change in Pao2/Fio2 ratio) to prone position. DESIGN: An observational prospective study. SETTING: From October 21, 2020, to 30 March 30, 2021. At the Sainte Anne military teaching Hospital and the Timone University Hospital. PATIENTS: Fifty consecutive patients admitted in our ICUs, with COVID-19 acute respiratory distress syndrome and required mechanical, were included. Twenty-four (48%) received prone ventilation. Fifty-eight prone sessions were investigated. INTERVENTIONS: An electrical impedance tomography recording was made in supine position, daily and repeated just before and just after the prone session. The daily dependent area collapse was calculated in relation to the previous electrical impedance tomography recording. Prone ventilation response was defined as a Pao2/Fio2 ratio improvement greater than 20%. MEASUREMENT AND MAIN RESULTS: The main outcome was the correlation between dependent area collapse and the oxygenation response to prone ventilation. Dependent area collapse was correlated with oxygenation response to prone ventilation (R2 = 0.49) and had a satisfactory prediction accuracy of prone response with an area under the curve of 0.94 (95% CI, 0.87-1.00; p < 0.001). Best Youden index was obtained for a dependent area collapse greater than 13.5 %. Sensitivity of 92% (95% CI, 78-97), a specificity of 91% (95% CI, 72-97), a positive predictive value of 94% (95% CI, 88-100), a negative predictive value of 87% (95% CI, 78-96), and a diagnostic accuracy of 91% (95% CI, 84-98). CONCLUSIONS: Dependent lung areas collapse (> 13.5%), monitored by electrical impedance tomography, has an excellent positive predictive value (94%) of improved oxygenation during prone ventilation.

A national healthcare response to intensive care bed requirements during the COVID-19 outbreak in France.

BACKGROUND: Whereas 5415 Intensive Care Unit (ICU) beds were initially available, 7148 COVID-19 patients were hospitalised in the ICU at the peak of the outbreak. The present study reports how the French Health Care system created temporary ICU beds to avoid being overwhelmed. METHODS: All French ICUs were contacted for answering a questionnaire focusing on the available beds and health care providers before and during the outbreak. RESULTS: Among 336 institutions with ICUs before the outbreak, 315 (94%) participated, covering 5054/5531 (91%) ICU beds. During the outbreak, 4806 new ICU beds (+95% increase) were created from Acute Care Unit (ACU, 2283), Post Anaesthetic Care Unit and Operating Theatre (PACU & OT, 1522), other units (374) or real build-up of new ICU beds (627), respectively. At the peak of the outbreak, 9860, 1982 and 3089 ICU, ACU and PACU beds were made available. Before the outbreak, 3548 physicians (2224 critical care anaesthesiologists, 898 intensivists and 275 from other specialties, 151 paediatrics), 1785 residents, 11,023 nurses and 6763 nursing auxiliaries worked in established ICUs. During the outbreak, 2524 physicians, 715 residents, 7722 nurses and 3043 nursing auxiliaries supplemented the usual staff in all ICUs. A total number of 3212 new ventilators were added to the 5997 initially available in ICU. CONCLUSION: During the COVID-19 outbreak, the French Health Care system created 4806 ICU beds (+95% increase from baseline), essentially by transforming beds from ACUs and PACUs. Collaboration between intensivists, critical care anaesthesiologists, emergency physicians as well as the mobilisation of nursing staff were primordial in this context.

Maintaining a high inspired oxygen fraction with the Elisée 350 turbine transport ventilator connected to two portable oxygen concentrators in an austere environment.

BACKGROUND: Management of critically ill patients requiring mechanical ventilation in austere environments or during disaster response is a logistic challenge. Availability of oxygen cylinders for mechanically ventilated patient may be difficult in such a context. A solution to ventilate patients requiring high fraction of inspired oxygen (FiO2) is to use a ventilator able to be supplied by a low-pressure oxygen source connected with two oxygen concentrators (OCs). We tested the Elisée 350 (ResMedBella Vista, Australia) ventilator paired with two Newlife Intensity 10 (Airsep, Ball Ground, Georgia) OCs and evaluated the delivered FiO2 across a range of minute volumes and combinations of ventilator settings. METHODS: The ventilators were attached to a test lung, OC flow was adjusted with a Certifier FA ventilator test systems from 2 to 10 L/min and injected into the oxygen inlet port of the Elisée 350. The FiO2 was measured by the analyzer integrated in the ventilator, controlled by the ventilator test system. Several combinations of ventilator settings were evaluated to determine the factors affecting the delivered FiO2. RESULTS: The Elisée 350 ventilator is a turbine ventilator able to deliver high FiO2 when functioning with two OCs. However, modifications of the ventilator settings such as an increase in minute ventilation affect delivered FiO2 even if oxygen flow is constant on the OC. CONCLUSION: The ability of two OCs to deliver high FiO2 when used with a turbine ventilator makes this method of oxygen delivery a viable alternative to cylinders to ventilate patients requiring an FiO2 of ≥80% in austere place or during disaster response. LEVEL OF EVIDENCE: Feasibility study on test bench, level V.