Vomiting and diarrhoea

A 6 year old boy presents with a 1 day history of abdominal pain with some vomiting. Observations: Heart Rate 140, Respiratory Rate 40, Oxygen saturations 99% air, Capillary refill time 3 seconds, Temperature 38.1 degrees. On examination, he appears pale and thin.  His abdomen is diffusely tender. You notice on examination he is work of breathing is more increased than you would expect. His chest is clear, and his heart sounds are normal. What is the next best step?

A 3 year old attends with a 2 day history of diarrhoea and vomiting with an associated temperature. She has not been at school since her illness started, and for the last 24 hours, she has not kept anything down, and has only passed urine once. Her mum states that her older sibling had a similar illness that lasted 3 days and he is now better. Observations: Heart rate 160, Respiratory Rate 35, Temperature 38 degrees, Capillary refill time 3 seconds, her BP has not been measured. On examination is sleepy but rousable. She has cool peripheries and a mottled appearance to her skin. What’s the best course of action?