• The patient complains of burning, stinging, pain or any acute change at the injection site. The patient is often the first person to become aware that something is wrong with their IV therapy, so instruct them at the beginning of treatment to inform staff of any acute change during treatment. Explain the reason for this in a way which is not frightening but conveys the need for the patient's input and participation. Give reassurance that, if a leakage of drug should occur, it would probably not cause serious problems if the infusion is promptly stopped and the correct treatment instituted. Patients who are unable to communicate should be particularly closely observed.
  
  
• Induration, erythema, venous discoloration or swelling is observed at the site (discoloration alone may not indicate extravasation as doxorubicin, epirubicin and mitozantrone have been reported to produce this).
  
  
• No blood return is obtained. A lack of blood return from the cannula is commonly quoted as a sign that extravasation has occurred. It is however, the most misleading of all signs and has been implicated in a number of serious incidences. This occurs because although there has been extravasation injury and the cannula has become displaced, the act of trying to draw blood back to test for blood return moves the cannula back into the vein. Thus blood is returned, however, there is a hole in the vein wall in the proximity of the cannula tip. So when administration recommences, a larger and more significant extravasation injury ensues. Alternatively, the bevel of the needle can puncture the vein wall during venepuncture, allowing drug to escape into the tissue whilst the lumen of the needle may still remain in the blood vessel and allow adequate blood return.
  
  
• The flow rate is reduced. A reduced rate may be observed when using an infusion pump, so close observation is necessary.
  
  
• Increased resistance to the administration, once possible changes in the position of the body e.g. bending of wrist or elbow, or cannula support e.g. the bandaging, have been excluded as possible causes of the increased resistance, then a displaced cannula and hence extravasation are the next most likely causes. This is often one of the first signs of a problem or of pre-extravasation syndrome.

The Extravasation Syndrome

1. Pre-extravasation syndrome.     In general, this is either pre-extravasation syndrome or a type I or type II extravasation injury. The pre-extravasation syndrome (PES) often involves little or no leakage, but particularly severe phlebitis and / or local hypersensitivity together with a number of other local risk factors e.g. difficult cannulation, one (but not multiple) patient symptoms, and is probably the easiest to treat by withdrawing IV therapy immediately to prevent further deterioration to a fullblown type I or type II extravasation. It should however, be remembered that if patients have shown a susceptibility towards pre-extravasation syndrome, further administration should proceed with extreme caution and ideally in the contra-lateral limb to where the problem was diagnosed.
   
   
2. Type I extravasations.      Type I extravasation injuries raise a bleb or blister and have a defined area of increased firmness around the injury site. Type I injuries are most commonly associated with rapid intravenous bolus-type injections where the pressure applied by the person administering the drugs causes fluid to collect around the injury site. Type I injuries also occur when IV infusions are administered through over-pressurised pumps.
   
   
3. Type II extravasations.      Type II extravasation injuries are those characterised by soft, diffuse 'soggy' tissue- type injuries, where obvious dispersal into the intracellular space has occurred. This type of injury is most commonly associated with the gravity-fed IV infusion, or a bolus injection given into the side-arm of a free-flowing IV infusion, which has become subtly or partially dislodged. The treatment of both of these types of injury is the same. However, the success at different points in the treatment pathway can be dramatically different.