Acute Caremiddle twist
A 7-year-old boy is brought to the emergency department because he has been breathing hard since the morning. He has vomited repeatedly for two days and says his abdomen is sore; it is soft and generally tender with no guarding. He is drowsy but rousable. His respiratory rate is 36, deep and unlaboured, with no recession and no added sounds. Oxygen saturation 99% in air, heart rate 138, temperature 36.8 degrees Celsius. Which one of the following investigations will explain his breathing most quickly?