RESUMEN
<p><b>OBJECTIVE</b>To investigate the effect of a continuous infusion of low-dose dexmedetomidine on patient-controlled analgesia (PCA) with fentanyl in elderly patients after total hip replacement.</p><p><b>METHODS</b>Forty patients (ASA I-II) aged 66-81 years after total hip replacement were randomized equally into the control and test groups. The patients in the test group received continuous infusion of dexmedetomidine at the rate of 0.2 µg·kg(-1)·h(-1) from the beginning to the end of PCA with fentanyl after the surgery, while those in the control group received normal saline. The cumulative fentanyl dose, VAS pain scores and Ramsay sedation score were recorded at 0, 4, 8, 12 and 24 h after the surgery.</p><p><b>RESULTS</b>All the patients in the two groups reported good pain relief and none needed additional fentanyl. The VAS pain score was significantly lower (P<0.05 or 0.01), while the Ramsay sedation scores higher (P<0.05) in the test group than in the control group. The cumulative fentanyl dose was significantly lower in the test group (P<0.05 or 0.01). The incidence of such adverse effects as nausea and vomiting was significantly lower in the test group (P<0.05).</p><p><b>CONCLUSION</b>PCA with fentanyl combined with low-dose dexmedetomidine infusion is safe for elderly patients, and can decrease fentanyl consumption and improve the effect of PCA with fentanyl.</p>