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Interaction of Cobalamin Status With Nitrous Oxide in Relation to Postoperative Cognitive Changes in the Elderly

NCT00212147 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 444

Last updated 2022-08-08

No results posted yet for this study

Summary

Low cobalamin (vitamin B12) levels are frequent in the elderly. Most often they reflect a mild metabolic abnormality without clinical symptoms (subclinical cobalamin deficiency). It is unclear if these elderly people require medical intervention, unlike that small minority with clinical symptoms which can progress and create severe blood or nervous system problems. The study aims to determine if nitrous oxide (N2O), a common anesthetic agent, worsens cobalamin status in elderly patients with unrecognized subclinical cobalamin deficiency. The reason for concern is that N2O inactivates cobalamin and can aggravate the clinical picture of patients who already have clinical manifestations of cobalamin deficiency. The elderly are known to have an increased risk of developing mental changes after surgery and it may be that sometimes these result from aggravation of subclinical cobalamin deficiency.

The study recruits people over the age of 60 years who are undergoing clinically indicated elective surgery requiring general anesthesia for more than 1 hour. Patients meeting exclusion and inclusion criteria are randomized to receive either a standard anesthetic regimen that includes N2O or a nearly identical one without N2O. Before surgery and 2 weeks and 4 weeks after surgery, each patient undergoes (1) a broad battery of tests of cognition and mood and (2) blood tests measuring cobalamin, folate and homocysteine-methionine metabolism to determine whether they have any subtle biochemical impairment of cobalamin status. DNA from blood cells is also tested for the presence of common mutations that affect key enzymes in those metabolic pathways. A brief testing for postoperative delirium is also done 2 hours after surgery.

The patient subgroups' are analyzed for neuropsychologic changes over time, using the preoperative test as the baseline for all comparisons, and associations of those changes with metabolic, genetic, demographic and clinical data.

The primary question is what effect routine N2O exposure has on the latter compared with non-N2O anesthesia in elderly people who either have or do not have subclinical cobalamin deficiency. It will help answer whether or not the combination can help explain the increased risk of cognitive problems after surgery in elderly patients, and by extension whether preoperative cobalamin testing and treatment may be indicated in the elderly. It will also test whether genetic predisposition affects the described problems.

Conditions

  • Avitaminosis
  • Delirium, Dementia, Amnestic, Cognitive Disorders

Interventions

DRUG

General anesthesia with nitrous oxide

DRUG

General anesthesia without nitrous oxide

Sponsors & Collaborators

  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

    lead NIH

Principal Investigators

  • Ralph Carmel, MD · New York Presbyterian Brooklyn Methodist Hospital

Study Design

Allocation
RANDOMIZED
Purpose
DIAGNOSTIC
Masking
DOUBLE
Model
PARALLEL

Eligibility

Min Age
60 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2003-09-30
Primary Completion
2008-08-31
Completion
2008-08-31

Countries

  • United States

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00212147 on ClinicalTrials.gov