Carl, an elementary student, was rushed to the hospital due to vomiting and a decreased level of consciousness. The patient displays slow and deep (Kussmaul breathing), and he is lethargic and irritable in response to stimulation. He appears to be dehydrated — his eyes are sunken and mucous membranes are dry — and he has a two week history of polydipsia, polyuria, and weight loss. Measurement of arterial blood gas shows pH 7.0, PaO2 90 mm Hg, PaCO2 23 mm Hg, and HCO3 12 mmol/L; other results are Na+ 126 mmol/L, K+ 5 mmol/L, and Cl- 95 mmol/L. What is your assessment?