Namenda as Prevention for Post-Operative Delirium

Objectives of this double blind placebo-controlled study are to determine the efficacy, safety and tolerability of Namenda in the prevention of post-operative delirium as defined by DSM-IV-TR categories 293.0 Delirium due to medical condition or medications, and 780.09 Delirium NOS. The incidence of post-operative delirium is 10-50% of general surgical cases, depending on the population studied. Delirium is known to affect mortality and morbidity, and increase the length of stay of patients. Hospital mortality estimates in patients with delirium range from 10-65%, estimated to be 2-20 times that of control patients without delirium. Delirium is an independent prognostic determinant of hospital outcomes, including death, new nursing home placements and functional decline. Delirium is an independent marker for increased mortality among older medical inpatients in the 12 months post hospitalization, particularly in those patients without dementia.

Delirium may be better understood by a Multifactorial Model of Delirium, which involves a complex inter-relationship between predisposing Factors/Vulnerability and Precipitating Factors/Insults.

If higher risk factors can be identified, then preventive interventions targeted to these groups may be able to significantly reduce morbitity, possibly mortality, but at minimum improve the quality of life of those patients who otherwise would have gone through such an enormously traumatic and disturbing experience as the psychosis and disorientation of a delirium.

The Academy of Psyhosomatic Medicine Task Force on Mental Disorders in General Medical Practice, found that co-morbid delirium increased hospital length of stay: 100% in general medical inpatients, 114% in elderly patients, 67% in stroke patients, 300% in critical care patients, 27% in cardiac surgery patients, and 200-250% in hip surgery patients.

Overall Design and Plan of Study: 30 Surgical patients (type of elective surgery: total hip and total knee replacements) will be randomized into two arms of the study attempting to get a similar mean age for each group: Group 1: 15 patients receive placebo Day --8,--7,--6,--5,--4,--3,--2,--1,Day 0 (surgery), Post-op day 1,2,3, and 4. Group 2: 15 patients receive (10 mg) of Namenda (memantine) Day --8,--7,--6,--5,--4,--3,--2, then 20 mg per day on Day --1, day 0 (surgery), Post-op day 1,2,3 then 10 mg per day Post-op day 4, then stop Namenda.