Parenteral hydration and the cognitively impaired: the important role of subcutaneous hydration

Dehydration is common among those admitted to hospital with delirium or dementia and may itself contribute to cognitive impairment. Agitated behaviors are also common in such patients and may lead to difficulty in maintenance of peripheral IV cannulas. In this paper, we examine the potential advantages and drawbacks of subcutaneous (SC) compared with intravenous (IV) hydration in patients with cognitive impairment and mild-to-moderate dehydration.

We reviewed and summarized the available literature on SC versus IV hydration in patients with cognitive impairment and the impact on agitation and cannula maintenance in particular.

Compared with IV hydration, SC hydration is faster to establish and associated with fewer adverse effects. A meta-analysis of randomized controlled trials found that SC hydration in patients with cognitive impairment results in a lower risk of agitation (relative risk 0.40 [95% CI 0.22-0.72]) compared with IV hydration. Furthermore, there is an 80% reduced risk of catheter dislodgment. It is likely that the reduced risk of agitation and catheter dislodgment is causally related to the fact that subcutaneous access is less traumatic approach for a population at high risk for agitation.

SC hydration has many advantages and few disadvantages for those with mild-to-moderate dehydration and cognitive impairment who need parenteral hydration. It should, in our opinion, always be considered in this population. It is important, however, that ease of use does not lead to overuse, especially where low-intake dehydration may represent part of the natural course of advanced illness.