ICU - Random bits

Question 1

What are the main causes of anaemia in ICU?

Answer 1

• Dilutional
• Loss RBC
  > Extravascular loss - trauma, GI bleed
  > Intravasacular - haemolysis, DIC, extracorporeal
• Decreased production
  > decreased haemotinics- B12/folate, iron def
  > Decreased prolif - epo

Question 2

What is an over-damped waveform?

Answer 2

This happens when there is clot in the catheter tip, or an air bubble in the tubing. The higher frequency components of the complex wave which forms the pulse are damped to the point where they no longer contribute to the shape of the pulse waveform.

Question 3

What is an under-damped A line waveform?

Answer 3

Overly stiff circuit tubing or a defective transducer

Question 4

How does an A line work and where should it be positioned?

Answer 4

Intra-arterial catheter connected to a pressurised system with a pressure transducer that can convert changes in pressure to electrical current.

The transducer is zero’d to atmospheric pressure and then placed at the level of the right atrium.

Question 5

Describe an ECMO circuit

Answer 5

-cannulae
-tubing
-pump
-membrane oxygenator and heat exchanger
-gas blender
-Cannulae

15-23 Fr
arterial
venous
back flow
bicaval cannulae (available)
Tubing

therapeutic anticoagulation required (ACT 180-200)
all tubing is heparin bonded
blood must be kept flowing
Pump

centrifugal or roller
patients on VV don’t require a pump as patients heart is working
Oxygenator

large surface area
integrated heat exchange

Question 6

What are some of the causes of thrombocytopenia?

Answer 6

Dilution
- massive transfusion

Sequestration
- Hypersplenism
- Hepatic sequesteration

Decreased platelet production/Bone marrow suppression
- Alcohol toxicity
- Drugs: linezolid, Bactrim, etc
- Chemotherapy
- Congential causes, eg. Fanconi anaemia
- Myelofibrosis or aplastic anaemia
- Neoplasm, eg. leukaemia or lymphoma
- Viral infection, eg. HIV, EBV, Hep C, parvovirus, mumps, rubella, varicella…
- Nutritional deficiency: B12 and folate deficiency
- Liver disease - decreased production of thrombopoietin (TPO)

Increased platelet destruction
- SLE
- ITP
- DIC
- Drugs: Quinine, Heparin (HITTS), Valproate
- Post-transfusion thrombocytopenia
- Microangiopathic haemolytic anaemia
- Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS)
- Antiphospholipid syndrome
- HELLP syndrome in pregnancy
- Physical destruction in the cardiopulmonary bypass apparatus or circuit

Question 7

What are Pulmonary Renal Syndromes?

Answer 7

• Combination of diffuse alveolar haemorrhage and glomerulonephritis
• ANCA Positive - Eosinophilic granulomatitis with polyangitis, GPA, Microscopic polyangitis
• ANCA negative - IgA Vasculiitis (HSP), Behcets
• Immune Complex - SLE, RA, Systemic Sclerosis
• Anti-GBM - Goodpastures
• Other - Drugs - hydralazine, PTU, allopurinol

Question 8

What aret subtypes of vasculitis?

Answer 8

Large Vessel - GCA,
Medium - Polyarteritis Nodosa, Kawasaki
Small Vessel - ANCA (EGPA, EPA, Microscopic polyangitis, Non-ANCA - IgA, Bechets