Healthcare and Medicine Reference
In-Depth Information
Table 18.1 Causes of oliguria and anuria.
Box 18.2 Additional equipment for the insertion of a
suprapubic catheter
Renal artery stenosis (in combination with an ACE inhibitor)
Renal artery thrombosis
Hepatorenal syndrome
Acute tubular necrosis:
ischaemic secondary to reduced renal perfusion
In addition to the equipment listed in Box 18.1 you will need the
ultrasound machine
22G needle
local anaesthetic (e.g. 1% lidocaine)
10/20-mL sterile syringe
cystostomy kit, these vary widely between various manufacturers,
you should be familiar with the contents of the kit before you
need to use it!
catheter dressing.
toxins - e.g. myoglobin in rhabdomyolysis
drugs (e.g. gentamicin)
Infi ltrate the skin with local anaesthetic in the midline 2 cm
Vasculitis, for example:
infection (e.g. malaria)
superior from the pubic symphysis.
For aspiration, use a 22G needle (short length in children),
attached to a 10/20-mL syringe. Advance the needle while aspi-
rating until urine appears. In children the bladder is still an
abdominal organ so the needle should be angled slightly towards
the abdomen (cephalad). In adults the bladder is a pelvic organ so
the needle should be angled slightly towards the pelvic fl oor (cau-
dad). Once the sample is obtained, remove the needle and apply
pressure with gauze before applying a sterile dressing to the site.
For suprapubic catheter insertion you will have a cystostomy kit
drugs - NSAIDs, diuretics
herpes simplex virus
Ureteral obstruction
Bladder outlet obstruction
Renal calculi
Prostatic hypertrophy
Renal vein thrombosis
as part of your equipment set up on your sterile tray. At the site
of the aspiration, make a small incision with a scalpel.
Insert the trochar and cannula in the same direction as the aspira-
tion needle until the bladder is entered and you aspirate urine.
Remove the trochar - urine should now gush out of the distended
bladder. In some kits the cannula itself acts as the catheter which is
sutured in place and connected to the drainage bag. In others, a Foley
catheter is inserted through the cannula and the balloon infl ated.
The cannula then normally peels apart and can be removed.
Secure the catheter with a dressing.
Suprapubic catheterisation in a non-distended bladder can
be performed after fi lling the bladder with saline via a fl exible
cystoscopy. Occasionally, particularly if there has been lower
abdominal surgery, an open cystostomy under general anaesthetic
is necessary.
Why monitor urine output?
It is outside the scope of this topic to discuss in full the monitoring
of urine output. The production of urine is a refl ection of fl uid bal-
ance status of the body and how well the kidneys are functioning
to excrete waste products and regulate fl uid balance. A reduction in
urine output is a signal that all is not physiologically normal in the
body; this requires your attention.
Oliguria is a reduced urine output, defi ned as a urine output of
less than 300 mL in 24 hours, or better, less than 0.5 mL/kg/hour.
Anuria is the failure to produce any volume of urine and requires
urgent attention. Causes of reduced urine output can be prerenal,
renal and post-renal (Table 18.1).
Any patient with low urine output should be thoroughly assessed
as to the likely cause. Oliguria for more than 2 hours is an emergency.
If in doubt or the patient is not responding to initial treatment, get
senior advice.
These are rare but potentially serious.
Infection: superfi cial of the skin and subcutaneous tissues,
intra-abdominal or bladder.
Peritoneal perforation with or without visceral injury. Can be
potentially life-threatening if bowel is perforated and catheter left
in place. A vesicocolic fi stula may form.
Haematuria: as with urethral catheterisation this is usually tem-
porary and more commonly microscopic.
Inability to aspirate urine: you will need to contact the urology
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