failure are listed in Table 99.3 Appreciation of complicating underlying conditions and the current clinical status, including response to chronic therapy and details of prior exacerbations will help to assess those at risk of deteriorating respiratory failure and inform treatment decisions Triage Children with signs of impending or acute respiratory failure should be rapidly identified based on appearance or vital signs and immediately evaluated with attention to necessary lifesaving maneuvers Supplemental oxygen and support of ventilation should be provided emergently as indicated, while additional efforts to determine underlying etiology are being addressed Initial Assessment/H&P Diagnosis of acute respiratory failure is commonly made clinically, though laboratory or pulmonary function testing can be supportive Initial assessment involves prompt appraisal of the child’s appearance, level of alertness, airway patency, breathing effort, and circulation Resuscitative efforts may be necessary to clear or support an obstructed airway, provide oxygen, and support effective ventilation Initial history should be brief, focused, and succinct One approach to consider is the “AMPLE” history, which involves queries into allergies, medications, pertinent medical history, last meal, and events involved in present illness including treatments already administered Patients with acute respiratory failure should be continually assessed using cardiopulmonary monitoring of heart rate, cardiac rhythm, respiratory rate, pulse oximetry, and blood pressure Noninvasive monitoring of end-tidal carbon dioxide (ETCO2 ) (i.e., capnography) is also an important adjunct, providing information about ventilatory status, including adequacy of assisted ventilation if performed Management Management of acute respiratory failure is critical in the ED It involves performing necessary therapeutic interventions to assist oxygenation and ventilation along with close monitoring for further deterioration and consideration of appropriate diagnostic testing ( Table 99.4 ) Supplemental oxygen should be provided during initial assessment and any resuscitative efforts This is most appropriately accomplished using a nonrebreather mask for spontaneously breathing patients The goal oxygen saturation percentage may vary according to underlying and suspected acute