A 2-Month-Old With Unusual Tachypnea

Case ReportA 2-month-old previously healthy female born at 38 weeks gestation presented to a local emergency department (ED) with tachypnea.She had previously been evaluated at an urgent care for similar symptoms 3 weeks prior, at which time she was diagnosed with viral bronchiolitis and discharged with instructions for supportive care.At that time, chest radiograph showed inflammatory airway disease without focal pneumonia.On the day of return presentation, she was noted to be tachypneic with a respiratory rate of 70 breaths/min at her pediatrician's office, which prompted transfer to the ED via ambulance.She was started on supplemental oxygen via nasal cannula for her cyanotic appearance.Review of systems was positive for congestion, rhinorrhea, intermittent coughing paroxysms, and non-bloody, non-bilious post-tussive emesis.The infant was afebrile and without diarrhea.She had no known sick contacts.Initial vitals on ED presentation were: heart rate 188 beats/min, respiratory rate 70 breaths/min, blood pressure 82/55 mm Hg, rectal temperature 98.8°F (37.1°C), and oxygen saturation (SpO2) 100% on 1L via nasal cannula.On examination, she was alert and had moderate intercostal retractions, tachypnea, and globally coarse breath sounds.Her cardiac exam was remarkable only for tachycardia.Complete blood count was obtained and notable for white blood cell count of 19,400/uL and platelet count 573,000/uL with normal hemoglobin and hematocrit.A basic metabolic panel showed mild metabolic acidosis but was otherwise normal.A venous gas showed a pH at 7.34 and PCO2 of 38.Respiratory viral panel, SARS-CoV-2, and pertussis testing, all via polymerase chain reaction (PCR) swabs, were negative.Chest radiograph showed bilateral upper lobe opacities (Figure 1).She was treated with empiric ampicillin and azithromycin and admitted to the hospital.