Healthcare and Medicine Reference
Figure 10.4 Step-by-step guide: intravenous cannulation. (a) Tourniquet on
the forearm. (b) Sterilising the insertion site with 2% chlorhexidine gluconate in
70% isopropyl alcohol. (c) The insertion angle of 10-30°. (d) The fi rst fl ashback
seen in the hub of the cannula. (e) Secondary fl ashback in the cannula itself.
(f) The cannula fully inserted. (g) Gauze underneath the cannula to prevent
blood spillage. (h) Removing the needle from the cannula. (i) The cannula
fully dressed and dated (the insertion point can be easily observed through
the dressing). (j) The cannula is fl ushed with 0.9% saline.
Figure 10.6 Taking blood out of a cannula. Blood is withdrawn from the
cannula using a 10-mL syringe.
Haematoma formation is a common complication of cannu-
lation. A collection of blood forms in the soft tissue following
leakage of blood from a venous puncture site. Haematoma is a
common feature of failed cannulation or accidentally displaced
cannulae. It is often more severe in those who are anticoagu-
lated or have deranged clotting. The cannula must be removed
Figure 10.5 Diagrammatic representation of cannulation. (a) The needle
and cannula enter the lumen of the vein. The primary fl ashback is seen.
(b) The needle is withdrawn and the cannula advanced into the lumen.
The secondary fl ashback is seen.