Subcutaneous rehydration, also called hypodermoclysis, is a useful alternative to intravenous (IV) rehydration, particularly in geriatric patients who have limited venous access. Hypodermoclysis fell out of favor in the middle of the previous century because of improper application resulting in adverse effects. Recently, this hydration technique has received renewed attention. Slesak and colleagues conducted a prospective, randomized study to compare the acceptability of this hydration method with IV fluid administration. The responses of patients and health care personnel were evaluated.

Random allocation of hydration method was achieved by sealed envelope. Patients 60 years or older in need of parenteral fluids were included in the trial and assigned to receive IV or subcutaneous (SC) fluids. Primary end points were the scores of patients' discomfort, and nurse or physician assessment of feasibility on a scale of 1 to 6. In Germany, where this study was performed, physicians insert IV lines, whereas nurses initiate hypodermoclysis.

During a 20-month period, 96 patients were enrolled (48 patients in each group). A switch from SC rehydration to IV rehydration and vice versa was permitted at any time and occurred more frequently than expected: SC was switched to IV 13 times, and IV was switched to SC 17 times. Mean hospital stay and median duration of fluid administration did not differ significantly between the groups, but median volume was greater for the IV group. In an intention-to-treat analysis, there was no difference in patients' mean discomfort and nurses' feasibility scores. Physicians, however, scored feasibility significantly better in the SC group. There were no differences in the systemic side effects of the two methods.

This study differed from previous studies in the length of time that patients were followed. The high number of switches between methods likely reflects the duration of the study period. The authors conclude that SC rehydration is similar to IV rehydration in all parameters, including adverse effects, and may be easier to administer.