Emergency Medicine

Acid–Base, Electrolyte and Renal Emergencies 143

ACUTE RENAL FAILURE

(b) signs of volume overload: raised JVP, peripheral oedema and

respiratory crepitations in intrinsic renal disease.

(ii) Clinical manifestations of acute uraemia: sallow complexion,

asterixis (flap), pericardial or pleural rub, pulmonary oedema or

pleural effusion, altered mental status, confusion, seizures.

(iii) Signs of post-renal obstruction: enlarged prostate on per rectal

(p.r.) examination, cervical or uterine mass lesion on vaginal

examination.

6 Insert an i.v. cannula and send bloods for FBC, U&Es, LFTs, blood sugar, CK,
calcium and uric acid. Take an arterial blood gas analysis. Attach a cardiac
monitor to the patient.

7 Organize a bedside bladder scan to determine the presence of urinary reten-
tion, which may signal a post-renal obstruction cause.

8 Insert an indwelling catheter and send a midstream urine sample for urinary
osmolality and electrolyte screen to help distinguish a pre-renal from an
intrinsic renal cause of renal failure.
(i) Request microscopy for signs of glomerulonephritis such as red
cell casts or >70% dysmorphic red cells, and for myoglobinuria,
haemoglobinuria (absent red cells) or evidence of infection.

9 Take an ECG to look for signs of hyperkalaemia, or an arrhythmia such as
atrial fibrillation which may, for instance, be associated with renal embolic
disease.

10 Request a CXR to look for volume overload, metastatic disease and pul-
monary–renal syndromes such as Wegener’s granulomatosis.

11 Arrange an urgent renal tract ultrasound to look at the size of the kidneys,
particularly looking for evidence of obstruction anywhere from the renal
pelvis to the bladder outlet.
(i) Shrunken kidneys suggest an acute on chronic process.
(ii) Exceptions are polycystic kidneys, amyloid or HIV nephropathy,
and diabetic nephropathy, which are associated with enlarged or
preserved renal size even with chronic renal failure.

MANAGEMENT

1 Determine the need for urgent treatment.
(i) Treat severe hyperkalaemia with 10% calcium chloride 10 mL
i.v. over 2–5 min, repeated until the ECG and cardiac output
normalize (see p. 132).
(ii) Treat accelerated hypertension and any suspected sepsis
including urinary tract.
(iii) Avoid nephrotoxic drugs such as NSAIDs and iodinated contrast.
(iv) Arrange early haemodialysis for patients with volume overload