Q. A 9-year-old girl with a known history of asthma is brought to your clinic with acute wheezing, increased shortness of breath, and chest tightness. The child's parents state that these symptoms began suddenly and have progressively worsened over the past few hours. She has been given short-acting beta agonist (SABA) inhalation twice 20 minutes apart. Her temperature is 98.6°F (37°C), pulse 120 beats per minute, blood pressure 110/70 mmHg, and respiratory rate 23 per minute. Her oxygen saturation on room air is 93%. The child appears anxious, agitated, and cyanosed. On physical examination, she is using accessory muscles to breathe and has prolonged expiration. On auscultation, widespread wheezing was heard in both lungs. What is the most appropriate initial intervention for this child?