Emergency Medicine

DIABETIC COMA AND PRE-COMA

General Medical Emergencies 79

4 Establish venous access and send blood urgently for FBC, ELFTs, blood
glucose and blood cultures if infection is suspected. Attach a cardiac monitor
and pulse oximeter to the patient.

5 Take blood for a bedside venous blood gas (VBG) or an ABG, and organize
an ECG, CXR and a midstream urine (MSU).
(i) Look at the ECG for an early indication of critical hyperkalaemia
with peaked T waves, QRS widening, then absent P waves and
finally a ‘sine wave’ trace (see p. 132).

MANAGEMENT

1 Give high-dose oxygen via a face mask and aim for an oxygen saturation
above 94%.

2 Start an i.v. infusion and run in normal saline 1 L in the first hour, followed
by a further 500 mL/h for the next 4 h if the diagnosis is confirmed.
(i) Continue the i.v. normal saline resuscitation until the blood
sugar is ≤15 mmol/L, then change to 5% dextrose but continue
the insulin infusion until the ketones are cleared.
(ii) Aim to replace the fluid deficit steadily over the first 24 h.

3 Commence short-acting soluble insulin therapy by infusion.
(i) Add 50 units soluble insulin to 50 mL normal saline, i.e. 1 unit/mL.
(ii) Run at 0.1 units/kg/h, i.e. 5–7 units/h or 5–7 mL/h via an infusion
pump.

4 Add potassium to the i.v. f luid when the plasma K level is known. This should
be wit hin 30 min:
(i) Potassium is <3.0 mmol/L – add potassium chloride (KCl)
40 mmol/L (3 g KCl). Must give via an infusion pump. Repeat
the serum level within the hour and adjust rate.
(ii) Potassium is 3.0–4.0 mmol/L – add 26.8 mmol KCl/L (2 g KCl).
(iii) Potassium is 4.0–5.0 mmol/L – add 20 mmol KCl/L (1.5 g KCl).
(iv) Potassium is 5.0–6.0 mmol/L – add 13.4 mmol KCl/L (1 g KCl).
(v) Omit the potassium if:
(a) no urine output is established (unusual)
(b) the serum level is >6.0 mmol/L
(c) the ECG shows peaked T waves or QRS complex widening.

5 Refer the patient to the medical team or ICU. Remember to have looked for
any underlying precipitating factor(s) for the DKA.

6 Do not give i.v. sodium bicarbonate except on the advice of the senior ED
doctor.

Tip: every patient who presents with abdominal pain, vomiting or thirst

✓ must have urine tested for sugar and ketones.