<prompt> A patient had a massive bleeding during surgery. Which sized cannula should be used?16 Gauge20 Gauge22 Gauge24 Gauge  <response>: Ans. a. 16 Gauge Ref: Bailey 25e p291In a patient with massive bleeding, there is always a risk of patient going into shock and widest bore cannula available showed be used for cannulation. The ACLS guidelines recommend securing intravenous access with two large-bore cannulae 14-16G in a patient needing resuscitation.Primary surrey in Trauma: These include blood samples for full blood count FBC, coagidation studies, plasma chemistry urea and electrolytes and, sometimes, toxicology or other case-specific indices, transfusion screening group and cross-match, etc,, 12-lead electrocardiography ECG monitoring and pulse oximetry, if available. The blood can be taken at the same time as securing intravenous access with two large-bore cannulae 14--16G.- Bailey 25e p29The sizes of needle-based instruments such as Venflons and needles themselves are measured in Gauge i.e. how many can be fitted into a tube of a fixed diameter. In Gauge, larger numbers, mean smaller diameter lumens. Catheters use the French system. This is the circumference of the tube in millimeters, e.g. a 30 F catheter has a circumference of 30 mm. In French, larger numbers therefore mean larger diameter lumens. GaugeColor codeExternal DiameterLengthFlow Rate14GOrange2.1 mm45 mm240 mlmin16GGrey1.8 mm45 mm180 mlmin18GGreen1.3 mm3245 mm90 mlmin20GPink1.1 mm32 mm60 mlmin22GBlue0.9 mm25 mm36 mlmin24GYellow0.7 mm19 mm20 mlmin26GViolet0.6 mm19 mm13 mlmin 