High flow nasal cannula for adult acute hypoxemic respiratory failure in the ED setting.

INTRODUCTION: High flow nasal cannula (HFNC) is a noninvasive ventilation (NIV) system that has demonstrated promise in the emergency department (ED) setting. OBJECTIVE: This narrative review evaluates the utility of HFNC in adult patients with acute hypoxemic respiratory failure in the ED setting. DISCUSSION: HFNC provides warm (37 °C), humidified (100% relative humidity) oxygen at high flows with a reliable fraction of inspired oxygen (FiO2). HFNC can improve oxygenation, reduce airway resistance, provide humidified flow that can flush anatomical dead space, and provide a low amount of positive end expiratory pressure. Recent literature has demonstrated efficacy in acute hypoxemic respiratory failure, including pneumonia, acute respiratory distress syndrome (ARDS), coronavirus disease 2019 (COVID-19), interstitial lung disease, immunocompromised states, the peri-intubation state, and palliative care, with reduced need for intubation, length of stay, and mortality in some of these conditions. Individual patient factors play an important role in infection control risks with respect to the use of HFNC in patients with COVID-19. Appropriate personal protective equipment, adherence to hand hygiene, surgical mask placement over the HFNC device, and environmental controls promoting adequate room ventilation are the foundation for protecting healthcare personnel. Frequent reassessment of the patient placed on HFNC is necessary; those with severe end organ dysfunction, thoracoabdominal asynchrony, significantly increased respiratory rate, poor oxygenation despite HFNC, and tachycardia are at increased risk of HFNC failure and need for further intervention. CONCLUSIONS: HFNC demonstrates promise in several conditions requiring respiratory support. Further randomized trials are needed in the ED setting.

Hemophagocytic Lymphohistiocytosis in the Emergency Department: Recognizing and Evaluating a Hidden Threat.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hematologic disorder resulting from an ineffective and pathologic activation of the immune response system that may mimic common emergency department presentations, including sepsis, acute liver failure, disseminated intravascular coagulation, and flu-like illnesses such as coronavirus disease 2019 (COVID-19). OBJECTIVE: This narrative review provides a summary of the disease and recommendations for the recognition and diagnostic evaluation of HLH with a focus on the emergency clinician. DISCUSSION: Though the condition is rare, mortality rates are high, ranging from 20% to 80% and increasing with delays in treatment. Importantly, HLH has been recognized as a severe variation of the cytokine storm associated with COVID-19. Common features include a history of infection or malignancy, fever, splenomegaly or hepatomegaly, hyperferritinemia, cytopenias, coagulopathies, abnormal liver enzymes, and hypertriglyceridemia. Using specific features of the history, physical examination, laboratory studies, and tools such as the HScore, HLH-2004/2009, and hyperferritinemia thresholds, the emergency clinician can risk-stratify patients and admit for definitive testing. Once diagnosed, disease specific treatment can be initiated. CONCLUSION: This review describes the relevant pathophysiology, common presentation findings, and a framework for risk stratification in the emergency department.

Initial emergency department mechanical ventilation strategies for COVID-19 hypoxemic respiratory failure and ARDS.

INTRODUCTION: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging viral pathogen that causes the novel coronavirus disease of 2019 (COVID-19) and may result in hypoxemic respiratory failure necessitating invasive mechanical ventilation in the most severe cases. OBJECTIVE: This narrative review provides evidence-based recommendations for the treatment of COVID-19 related respiratory failure requiring invasive mechanical ventilation. DISCUSSION: In severe cases, COVID-19 leads to hypoxemic respiratory failure that may meet criteria for acute respiratory distress syndrome (ARDS). The mainstay of treatment for ARDS includes a lung protective ventilation strategy with low tidal volumes (4-8 mL/kg predicted body weight), adequate positive end-expiratory pressure (PEEP), and maintaining a plateau pressure of < 30 cm H2O. While further COVID-19 specific studies are needed, current management should focus on supportive care, preventing further lung injury from mechanical ventilation, and treating the underlying cause. CONCLUSIONS: This review provides evidence-based recommendations for the treatment of COVID-19 related respiratory failure requiring invasive mechanical ventilation.