Intravenous or subcutaneous rehydration in adults

Intravenous rehydration may be required in adults who:

• have clinical features of severe dehydration (see Assessing clinical and laboratory features of dehydration in adults)
• worsen or do not have a marked response to oral rehydrationGuarino, 2018
• have an associated ileus or ketonaemia.

For haemodynamically compromised patients, 10 to 20 mL/kg of lactated Ringer solution or sodium chloride 0.9% by rapid intravenous infusion is usually indicatedSemler, 2018. Repeat if required until the patient is haemodynamically stable. Close attention to fluid balance is particularly required in frail older patients, in patients on fluid restriction, patients with heart failure or those receiving renal replacement therapy. Ongoing fluid and electrolyte therapy is guided by response to therapy, serum electrolyte concentration, fluid deficit, ongoing losses and comorbidities.Guarino, 2018

Subcutaneous fluid administration (hypodermoclysis) can be useful if intravenous rehydration is not possible (eg in residential aged-care facilities) or if intravenous access is difficult.

A subcutaneous infusion of sodium chloride 0.9% can be given at a rate of up to 1 mL/minute (ie 60 mL/hour) at each site. Only sites with adequate subcutaneous fat (eg the anterior abdomen) should be used for subcutaneous infusions. Change the infusion site after every 2 litres of fluid, or earlier if there is evidence of bruising, erythema, leaking, pain or unresolved blanching at the site. Check the site for these features at least once every 2 to 4 hours.