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Investigations in PICU

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Blood Tests

  • It is common for ICU patients to have excessive and unnecessary blood testing. Some tests (e.g. coagulation tests) are also very expensive.
  • The PICU lab form is designed for the common tests ordered. Important points are:
    • Hb/plts/WCC (unchecked) is an analyser printout without technician review.
    • This will mainly be useful for checking platelets faster in a bleeding patient.
    • Coags should not be repeated daily as a routine (see below).
    • For heparin monitoring, only do an APTT.
    • For warfarin monitoring only do an INR.
    • [PICU] chemistry is urea, creat, Mg, PO4, alb, ALT, ALP, Bili.
    • Liver patients (e.g. transplant, severe liver disease) have the additional liver bloods (GGT, AST) as well as [PICU] chemistry.
    • Children on TPN should have triglycerides checked prior to starting TPN and then daily. Once on "full" TPN, if triglyceride level is normal (<2.0) then this can be done twice weekly.
  • The following should be done routinely. Nothing else should be done unless charted.

On admission

Acute admission FBC with diff, coag screen, [PICU] chemistry  blood gas
Surgical/elective admission Hb/plts/WCC, coag screen (unless recently  done in OR), blood gas

Children with arterial or central venous lines

Day 1
FBC with diff, coag screen, [PICU] chemistry
Daily from Day 2
FBC with diff
o If on inotropes, [PICU] chemistry
o Any liver or kidney dysfunction, [PICU] chemistry
o No inotropes nor liver or kidney dysfunction, urea/creat only
o Coags only if previously abnormal (PR≥1.3, APTT>37) or clinically indicated  (e.g. new liver dysfunction)
o APTT alone as per heparin protocols if receiving heparin
Blood gases
Arterial line 6 hrly as a routine except for:
- Cardiac and haemodynamically unstable patients - 4 hrly
- Single ventricle infants after surgery - 2 hrly over the first night
SVC saturation Only if SVC catheter (IJ or subclavian)
- Cardiac and haemodynamically unstable patients - 4 hrly first 12-24 hrs
- Single ventricle infants after surgery - 2 hrly first 12-24 hrs
Venous gases (no arterial line) 12-24 hrly

Children without arterial or central venous lines

On IV fluids Na, K, urea, creat, glucose (microcollect) - daily
Fully enterally fed Na, K, urea, creat, glucose (microcollect) - every second day (may be less  for longer term admissions)


Blood cultures

  • should always be taken by peripheral "stab" (can also be taken from a newly inserted CVC).
  • if CVC present, take culture from this as well if CVC sepsis suspected (this is very unusual if the catheter is <4-5 days old)
  • do not send off CVC catheter tips unless CVC sepsis is suspected and it is accompanied by a peripheral culture


  • Are expensive ($330 each) and take considerable time to perform.
  • If one has been done elsewhere, check the result of this first.
  • Do not repeat "to see if it has become negative".
  • Do standard NPA (full respiratory panel) on week days to be at lab by 14:00.
  • Full respiratory panel not available in the weekend unless critical to management. However RSV alone can be done. Request "BINAX RSV antigen test: Attention VIM on-call" and must be at lab by 11:00.


  • daily on cardiac surgery patients (may be less frequent with long stay patients)
  • daily on all other patients if oxygen requirement or ventilation pressures have increased significantly


  • order first thing/early in the day, especially weekends.

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  • Date last published: 13 September 2010
  • Owner: John Beca
  • Review frequency: 2 years