In some situations a venous cannula may be in place for a few minutes or hours, as for patients undergoing general anaesthesia, sedation before surgery, noxious clinical procedures, or diagnostic radiological investigations. However, in some clinical situations long term cannulation for weeks or months may be required - in the critically ill or cancer patients receiving long term opiate infusions for pain relief or chemotherapy. Patients and nursing staff are only too well aware of the negative aspects associated with venous cannulation, including pain and discomfort and infection. These may be underestimated and under-reported. Patients are known to complain of pain and discomfort not only during the actual procedure itself, but whilst the cannula is in place and symptoms may continue weeks and months after it has been removed.
Venous cannulation is a common procedure which appears to have been the subject of few RCTs.
It is an ideal subject for nursing research, as despite traditionally being a medical responsibility it is now increasingly done by nurses in their extended role. This brought to light some interesting studies on this subject, and the most interesting are reviewed. Some patients undergoing venous cannulation faint. Pain on cannula insertion depends to some extent on needle size - but subcutaneous injection of local anaesthetic itself causes pain. Patients had their eyes closed, and were asked to grade which was the more painful.