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Home ventilators for invasive ventilation of patients with COVID-19
Giacomo Monti, George Cremona, Alberto Zangrillo, Gaetano Lombardi, Chiara Sartini, Marianna Sartorelli, Sergio Colombo, Ary Serpa Neto, Giovanni Landoni
Crit Care Resusc 2020; 22 (3): 266-270
- Giacomo Monti 1
- George Cremona 2
- Alberto Zangrillo 1, 3
- Gaetano Lombardi 1
- Chiara Sartini 1
- Marianna Sartorelli 1
- Sergio Colombo 1
- Ary Serpa Neto 4, 5
- Giovanni Landoni 1, 3
- Arentz M, Yim E, Klaff L, et al. Characteristics and outcomes of 21 critically ill patients with COVID-19 in Washington State. JAMA 2020; doi: 10.1001/jama.2020.4326. [Epub ahead of print]
- Yang X, Yu Y, Xu J, et al. Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study. Lancet Respir Med 2020; doi: 10.1016/S2213-2600(20)30079-5. [Epub ahead of print]
- Punjabi NM. The epidemiology of adult obstructive sleep apnea. Proc Am Thorac Soc 2008; 5: 136-43
Increasing numbers of patients with chronic respiratory failure are being treated at home with small mechanical ventilators. 3
MethodsWe studied a cohort of consecutive ventilated patients in COVID-19-dedicated intensive care units (ICUs) at San Raffaele Scientific Institute, Milan, Italy. In a proof-of-concept study, patients receiving invasive ventilatory support (at any stage of the disease) were transitioned for 3 hours from the ICU ventilator to ventilators designed for support of patients with chronic respiratory insufficiency (the intervention period) and then back to ICU ventilators. Arterial blood gases were collected hourly during this period. In addition to descriptive analysis, we measured the coefficient of variation within each subject, calculated as the standard deviation divided by the mean.
Two devices were tested: the VEMO 150 (EOVE, VitalAire, Italy) and VIVO 55 (Breas, MedicAir, Italy) ventilators. The system used for each of the devices is described below. Supplementary oxygen was supplied at low pressure through the purpose-built inlet on both machines.
System for the VEMO 150Outflow port → Oximeter → Heat and moisture exchanger (HME) → In tube → Y pieces → HME → Tracheal tube and back to the inflow port (Figure 1).
System for the VIVO 55Outflow port → Oximeter → HME → In tube → Exhalation valve → HME → Tracheal tube (Figure 1).
ResultsOver 10 days, from 28 March to 7 April 2020, seven patients were enrolled in this case series, including one patient with few measurements. Ventilatory variables are shown in Table 1.
The arterial partial pressure of oxygen (Pao2) values at the beginning of the intervention ranged from 61.9 mmHg to 96.5 mmHg and, at the end, from 56.7 mmHg to 102.6 mmHg (Table 1 and Figure 2). From the beginning and during the intervention period, the variation in Pao2 values ranged from 4.9% to 13.1%, with the highest increase being from 61.9 mmHg to 79.7 mmHg and the highest decrease from 96.5 mmHg to 85.8 mmHg.
No patient developed worse hypoxaemia during the intervention period. Ventilators designed for support of patients with chronic respiratory insufficiency were able to offer a fraction of inspired oxygen (Fio2) level from 40% to 86%, with oxygen flows ranging from 8 L/min to 20 L/min.
Similarly, Arterial partial pressure of carbon dioxide (Paco2) (coefficient of variation, 3.0–9.3%) and pH (coefficient of variation, 0.0–0.3%) levels remained stable during the test, and a considerably increase in the Paco2 level (from 58.4 mmHg to 72.5 mmHg) was observed in only one patient (Table 1). The patient developed fever and hypoxia unrelated to the intervention, which persisted even after return to the ICU ventilator.
DiscussionIn this case series, seven critically ill patients with COVID-19 were ventilated with ventilators designed for support of patients with chronic respiratory insufficiency during a short period. As assessed by hourly arterial blood gases, Pao2, Paco2 and pH levels were kept constant during the intervention and only one patient developed worsening of the Paco2 level in the setting of ventilation unrelated to the intervention but related to high fever and clinical deterioration.
This proof-of-concept study has several limitations. First, this was a small case series that included no controls. Second, it is unclear if a longer period of ventilation would result in similar findings, although the findings for the first 3 hours are encouraging. Third, ventilation was provided by two specific ventilators; whether a different ventilator would have been associated with different outcomes cannot be determined.