Cytotoxic drugs may be administered as a direct bolus injection (Figure 23.2), a bolus via the side arm of a rapid infusion of 0.9% sodium chloride or a continuous infusion. The choice is dependent on (Wilkes [268]):

The advantage of the bolus injection is that the integrity of the vein and any early signs of extravasation can be observed more easily than during an infusion. However, bolus injections can increase the risk of venous irritation due to the constant contact of the drug with the intima of the vein, resulting in pain, which makes it difficult to differentiate between venous spasm and extravasation (Gabriel [80]). It could also lead to inappropriate rapid administration of the drug (Weinstein and Hagle [265]).

Bolus injections administered via the side arm of a rapid infusion of solution ensure greater dilution of potentially irritating drugs and enable rapid removal of the drug from the insertion site and smaller vessels. The disadvantages are that a small vein may not allow rapid flow of the infusate and this may result in the drug backing up the tubing, causing the practitioner to clamp the tubing while checking for blood return and flow rate of the infusate, therefore interrupting constant observation of the site (Gabriel [80]).

Adding the drug to an infusion bag allows for greater dilution, thus reducing the possibility of chemical irritation. Some drugs may only be administered as infusions owing to the type of side‐effects associated with them (e.g. hypotension with etoposide) and long‐term continuous infusions, for example of 5‐fluorouracil (5‐FU), may also be necessary to reduce the risk of side‐effects such as diarrhoea. Patency and device position cannot be easily assessed and the longer the infusion, the greater the possibility of device dislodgement, extravasation or infiltration and general complications associated with the device (Weinstein and Hagle [265]).