Pneumomediastinum in diabetic ketoacidosis

A17-year-old female with type 1 diabetes of six years duration, controlled on a basal-bolus insulin regime (48 units per day) had deliberately stopped her insulin for two days, resulting in diabetic ketoacidosis (DKA). Examination revealed the patient had Kussmaul (acidotic) breathing with respirations of 40 per minute; she was dehydrated with a strong odour of ketones on the breath. The pulse rate was 150 per minute (ECG: sinus tachycardia), BP 90/55 mmHg, oral temperature showed hypothermia, 34.2oC. The patient complained of precordial pain and auscultation revealed a clearly audible retrosternal ‘crackle’, particularly well heard at the left sternal edge. Laboratory investigations showed a plasma glucose of 30 mmol/L, plasma bicarbonate 2 mmol/L, sodium, potassium and urea of 121, 5.7 and 8 mmol/L respectively, and an arterial pH of 6.8. Routine haematology showed a marked leucocytosis (41 x 10 /L: 89% neutrophils) and blood cultures subsequently grew beta-haemolytic streptococci. The chest X-ray showed features of pneumomediastinum and pneumopericardium with subcutaneous emphysema in the right axilla and supra-clavicular fossae (see figure 1). Treatment consisted of intravenous saline and subsequently dextrose-containing fluids with appropriate potassium supplementation and a low-dose sliding scale insulin regime. Immediately after initial blood cultures were taken, intravenous ceftriaxone was started. By 48 hours the patient’s general condition had improved, the biochemical parameters were normal, the chest pain and the precordial ‘crackle’ sound had disappeared, as had the radiological signs of the pneumomediastinum. The patient was restarted on subcutaneous insulin regime.