Equipment

Question 1

Arterial line pressure transducer

Answer 1

• Transducer - transforms energy from one form to another
• Catheter in direct continuation with column of fluid under pressure in rigid/stiff tubing
• Sensitive diaphragm attached to strain gauge
• Wheatstone bridge set of resistors
• Fourier analysis to construct wave form

Dampening - reduces amplitude of oscillations - bubbles, kinks, long compliant tubing
Optimal dampening = 0.7

Question 2

LP

Answer 2

MC&S
Viral PCR
Biochem - protein, glucose, LDH
Xanth/bilirubin
Cytology

Question 3

PAC

Answer 3

2 lumens for fluids/drugs
1 lumen for balloon
Mixed venous sats monitor - SvO2
Thermistor and thermal filament
Cm markings

CO by thermal dilution

Question 4

Three compartment chest drain set

Answer 4

Issue with single chest bottle is that as more fluid fills a single chamber more positive pressure is required to expel further fluid or air.

Two chamber system has a drainage collection bottle first, an underwater seal in the second bottle with a constant 2cm below the water line seal.

Three chamber design adds a suction pressure regulator in the third bottle which regulates the suction using an underwater tube open to the air. Main disadvantage is that if the suction tube blocks then pressure will rise in the chambers and cause the pneumothorax to re-expand.

Question 5

Sengstaken-Blakemore tube

Answer 5

Gastric and oesophageal balloon

Can not be used with known oesophageal stricture or recent surgery

How to use:
Most patients I&V
Local anaesthetic and lubricate
Insert via nose or mouth to at least 50cm
Confirm with CXR
Inflate gastric balloon with 50ml aliquots up to 250-300mls
Pull ballon up to fundus and tape in place

Complications:
Pain
Haemorrhage
Oesophagael rupture 
Pressure necrosis - limit time inflated, only use for 24 hrs