The Role of Noninvasive Respiratory Management in Patients with Severe COVID-19 Pneumonia

Abstract

Acute hypoxemic respiratory failure is the principal cause of hospitalization, invasive mechanical ventilation and death in severe COVID-19 infection. Nearly half of intubated patients with COVID-19 eventually die. High-Flow Nasal Oxygen (HFNO) and Noninvasive Ventilation (NIV) constitute valuable tools to avert endotracheal intubation in patients with severe COVID-19 pneumonia who do not respond to conventional oxygen treatment. Sparing Intensive Care Unit beds and reducing intubation-related complications may save lives in the pandemic era. The main drawback of HFNO and/or NIV is intubation delay. Cautious selection of patients with severe hypoxemia due to COVID-19 disease, close monitoring and appropriate employment and titration of HFNO and/or NIV can increase the rate of success and eliminate the risk of intubation delay. At the same time, all precautions to protect the healthcare personnel from viral transmission should be taken. In this review, we summarize the evidence supporting the application of HFNO and NIV in severe COVID-19 hypoxemic respiratory failure, analyse the risks associated with their use and provide a path for their proper implementation.

Keywords: COVID-19; High Flow Nasal Oxygen; Noninvasive Ventilation; SARS-COV-2; noninvasive respiratory treatment.

Figure 1

Recommended algorithm for noninvasive respiratory support in COVID-19 patients with acute hypoxemic respiratory failure. Patients with PaCO₂ > 45 mmHg are excluded. # Criteria for immediate or imminent intubation are impaired consciousness, persistent shock (which is defined by systolic arterial blood pressure < 90 mmHg despite adequate fluid administration), hypercapnia/acidosis and deteriorating respiratory distress. ^® The choice between HFNO and NIV depends on device availability and familiarity. In case that both are available, HFNO is proposed as a first choice because of better patient tolerance and ease of use. & BiPAP could be a choice in case of respiratory distress. BiPAP initial pressure settings could be different, depending on the interface used, i.e., with helmet pressures it should be increased by 50%. * Respiratory distress is detected by the presence of persistent auxiliary muscle use and/or thoraco-abdominal asynchrony. £ The rationale of change in HFNO settings is the following: (a) increase in flow rate is expected to decrease the respiratory muscle workload with concomitant decrease in the respiratory rate, dyspnoea, auxiliary muscle use and thoraco-abdominal asynchrony; (b) increase in FiO₂ causes increase in PaO₂ and SpO₂; (c) temperature can be set at 37 °C or lower (31–34 °C) based on the patient’s comfort. ¥ Hemodynamic instability is defined by a heart rate >140 beats/min or change >20% from baseline and/or systolic arterial blood pressure > 180 mmHg, <90 mmHg or decrease >40 mmHg from the baseline. @ In case of HFNO failure, a short trial of NIV could be considered in the ICU/HDU area. ∞ BiPAP use should be as much as possible, ideally continuous. + If the patient’s clinical status and arterial blood gases are progressively improved, we proceed to weaning. BiPAP: Bilevel positive airway pressure; CPAP: continuous positive airway pressure; FiO₂: fraction of inspired oxygen; HACOR score: Heart rate–pH–Glasgow Coma Scale–PaO₂/FiO₂–respiratory rate; HFNO: High-Flow Nasal Oxygen; MV: Mechanical Ventilation; PaO2: arterial partial pressure of oxygen; PaCO₂: arterial partial pressure of carbon dioxide; PBW: predicted body weight; RR: respiratory rate; ROX index:ratio of SpO₂/FiO₂ to the respiratory rate; SpO₂: pulse oximetry of oxygen; SOT: standard oxygen treatment.