Approximately 5% of patients infected by COVID-19 require ICU admission due to acute respiratory distress syndrome (ARDS). Invasive mechanical ventilation is required in a large majority of these patients. Proper ventilatory management during ARDS reduces the risk of ventilator-induced lung injury and can also play a role in improving patient survival.
Some reports suggest that patients with COVID-19 ARDS may have different phenotypes, and this could have an impact on ventilator management. Some experts claim that COVID-19 patients may not necessarily benefit from regular ARDS management.
In this study, the researchers assess respiratory mechanics, potential for lung recruitment and PEEP effects in mechanically ventilated patients with COVID-19 induced moderate to severe ARDS. They compared the results to patients with ARDS of other origins who underwent the same procedures. The study was conducted in an ICU of a tertiary care university hospital in Italy. A 28-day clinical outcome was recorded.
Mechanical ventilation was applied in a volume-controlled mode at tidal volume 6 ml/kg of predicted body weight, inspiratory flow 60 l/min, inspiratory pause 0.3 s, respiratory rate titrated to obtain pH > 7.30 and < 35 breaths per minute, and FiO2 titrated to achieve SpO2 between 90 and 96%.
Two PEEP levels were tested - 15 and 5 cmH20. Peak airway pressure, pressure, and total PEEP were measured. Driving pressure, respiratory system compliance, and PBW-indexed value were also computed. Ventilatory ratio was calculated. Exhaled tidal volume after PEEP lowering was recorded, and recruitment-to-inflation ratio was computed.
COVID-19 patients were compared to patients with moderate-to-severe ARDS from other aetiologies. Ventilatory ratio, compliance, and its predicted body weight-indexed value were slightly higher in COVID-19 patients than in patients with ARDS of other aetiologies. Airway closure in the COVID-19 cohort was less frequent than in other ARDS patients. Average respiratory system compliance and respiratory system compliance/PBW were slightly higher in patients with COVID-19 compared to those in the non-COVID-19 ARDS group.The PEEP-induced improvement in PaO2/FiO2 was greater in COVID-19 patients than among subjects ARDS from other causes. Overall, the 28-day mortality of COVID-19 patients was higher than that reported for ARDS of other causes.
These findings suggest that patients with COVID-19 show a conventional ARDS phenotype, and physiological differences between COVID-19 patients and ARDS from other aetiologies appear clinically negligible.
Source: Critical Care
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