oral route is unavailable or unreliable (patient unable to swallow,
has dysphagia or odynophagia or has high proximal bowel obstruction)
pain is unstable and frequent dose adjustments are required.
Traditionally, intravenous or intramuscular routes are used to give
pain medications. Subcutaneous infusions are the preferred route in palliative
care for the following reasons:
Ongoing sub-cutaneous dosing is equivalent to and as effective
as ongoing intravenous dosing.
As death approaches, the burden of maintaining intra-venous access
is higher compared to sub-cutaneous access. Sub-cutaneous needles are
smaller (less painful) and easier to insert.
Sub-cutaneous pumps are smaller than intra-venous pumps and are
easily portable and therefore ideal for patients who are still ambulatory.
Limitations of sub-cutaneous infusions: Only small volume infusions
can be given sub-cutaneously (up to 3 cc/hour). Currently morphine
sulfate is available in a 20 mg/cc formulation. Therefore up to Morphine
sulfate infusion 60 mg/hour (equivalent to oral Morphine sulfate 180
mg/hour) can be given sub-cutaneously. If higher doses are required,
consider switching to a more potent opioid like hydromorphone (four
to seven times more stronger than morphine sulfate).
