Desflurane or Propofol Anesthesia in Elderly Obese Patients Undergoing Total Knee Replacement



Status:Completed
Conditions:Arthritis, Obesity Weight Loss
Therapuetic Areas:Endocrinology, Rheumatology
Healthy:No
Age Range:65 - Any
Updated:4/21/2016
Start Date:December 2010
End Date:July 2015

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Desflurane or Propofol Anesthesia in Elderly Obese Patients Undergoing Total Knee Replacement: A Pilot Assessment of Short-term and Long-term Differences in Outcome

You are invited to participate in a research study assessing your mental status in the first
days after your surgery and how you will be doing in the 2 years following the surgery. The
investigators hope to learn more about the incidence of postoperative confusion and a
possible relation with 2 anesthesia techniques that are routinely used. The first one is an
anesthesia technique that uses the inhaled anesthetic gas desflurane and the second one is
an anesthesia technique that uses the anesthetic propofol administered by infusion in a
vein. The investigators are also looking to see if there is a relationship between
anesthesia technique and cardiovascular outcomes. You were selected as a possible
participant in this study because at your age this phenomenon appears to have a greater
incidence.

Trial Objectives:

This will be a randomized, prospective, single-center, assessor blinded pilot study
comparing two different anesthesia techniques in 100 elderly obese patients undergoing
primary total knee arthroplasty.

Endpoints:

- The incidence of postoperative delirium as measured by the Confusion Assessment Score.
Confusion assessment score will be administered at baseline, one hour after arrival in
the post anesthesia care unit and 6-8, 24 and 48 hrs postoperatively.

- Cognitive function as measured by Test for Attentional Performance,
Digit-Symbol-Substitution Test, Recal of Digit Span , Well-being Test BF-S, Spielberger
State-Trait Anxiety Inventory and the Trail Making Test A and B. Cognitive function
tests will be administered at baseline, 6-8 and 48 hrs post operatively. Postoperative
Cognitive Dysfunction is defined as a 20% decline of the baseline values.

Intraoperative

- Sensory block (femoral)

- Blood pressure

- Heart rate

- Patient state index values

- Degree of neuromuscular blockade

- Esophageal temperature

- End tidal concentration of CO2

- End tidal concentration of desflurane

- Amount of vasopressors (ephedrine or phenylephrine)

- Amount of intravascular fluid administration

- Dose and mean infusion rates of all IV drugs (propofol)

- Duration of anesthesia

- Duration of surgery

- Time to spontaneous breathing after desflurane/propofol discontinuation

- Time to eye opening after desflurane/propofol discontinuation

- Time to tracheal extubation after desflurane/propofol discontinuation

- Time to following command after desflurane/propofol discontinuation

Post operative

- Nausea and vomiting: one hour after arrival in the post anesthesia care unit and 6-8,
24 and 48 hrs postoperatively

- Pain visual analogue score measured one hour after arrival in the post anesthesia care
unit and 6-8, 24 and 48 hrs postoperatively

- Recovery room time

- Amount of local anesthetics (ropivacaine)

- Amount of opioids (Patient controlled analgesia hydromorphone)

Cardiovascular

- B-type natriuretic peptide measured preoperatively and on postoperative days 1 and 2

- N-terminal proB-type natriuretic peptide measured preoperatively and on postoperative
days 1 and 2

- Troponin I measured preoperatively and on postoperative days 1 and 2

- Patients will be followed by a blinded investigator for a 2 year period to record the
development of cardiac complications defined by a broad composite that included cardiac
death and nonfatal myocardial infarction. Cardiac composite including: all-cause
mortality, acute myocardial infarction, unstable angina, congestive heart failure, new
atrial or ventricular dysrhythmia requiring treatment, and cerebrovascular insult.

Protocol This will be a randomized, prospective, single-center, assessor blinded study
comparing two different anesthesia techniques in 100 elderly obese patients undergoing
primary total knee arthroplasty. We expect to enroll all patients in a 2 year period.

The study will be performed according to the Declaration of Helsinki principles, and written
informed consent will be obtained from each patient. Preoperatively baseline values will be
obtained for the cardiovascular, mental status, respiratory and pain outcome measures.

Mental status: During their preoperative visit patients will be given the neuropsychological
tests in the following order: 1. Confusion Assessment Method . The confusion assessment
method is a screening instrument for delirium consisting of four clinical criteria: (1)
acute onset and fluctuating course, (2) inattention, (3) disorganized thinking, and (4)
altered level of consciousness. For a person to be considered delirious, both the first and
the second criteria and either the third or the fourth criteria have to be present. The
confusion assessment method has a high inter-observer reliability (0.8 -1.0), a sensitivity
of 94-100%, and a specificity of 90-95%. 2. Modified Mini-Mental State Examination. This
extended measure of general cognition was developed to overcome shortcomings of the
traditional Mini-Mental State Examination score, specifically its ceiling effects and narrow
range of possible scores. The Modified Mini-Mental State Examination will be administered at
the preoperative visit to assess the baseline cognitive function of the patient. 3.
Computerized Test for Attentional Performance , Digit-Symbol-Substitution Test, Recall of
Digit Span, Well-being Test BF-S, Spielberger State-Trait Anxiety Inventory and the Trail
Making Test A and B.

Patients will be visited for the first 2 days after surgery or until discharge, whichever
came first, and the confusion assessment method will be administered one hour after arrival
in the post anesthesia care unit and 6-8, 24 and 48 hrs postoperatively to determine whether
the patient is experiencing delirium. Each patient will be interviewed by the same trained
research assistant before surgery and during the postoperative visits. We will define the
occurrence of delirium as the patient meeting the confusion assessment method criteria for
delirium on any of the postoperative assessments. If a patient is positive for delirium, a
second member of the research team will be consulted to verify the diagnosis. Cognitive
function tests will be administered, 6-8 and 48 hrs post operatively. Postoperative
Cognitive Dysfunction is defined as a 20% decline of the baseline values.

Cardiovascular: Preoperative testing will include 12-lead ECG. Blood samples for Natriuretic
peptide levels and N-terminal proB-type natriuretic peptide and Troponin I will be obtained
at the time of the admission and on postoperative day 1 and day 2. Plasma NT-proB-type
natriuretic peptide will be determined using the Elecsys proB-type natriuretic peptide
sandwich immunoassay on an Elecsys 2010 (Roche Diagnostics, Basel, Switzerland). Two cut
offs for NT-proB-type natriuretic peptide will be selected before the analyses, 300 pg/ml
and 600 pg/ml, with a value of less than 300 pg/ml shown to be optimal for ruling out heart
failure as a predictor. B-type natriuretic peptide will be determined using
immunoradiometric assay kit. Values of B-type natriuretic peptide (pg/mL) 31.0 ± 2.4 are
considered normal for patients over 65 years old.

After discharge from the hospital patients will be followed blindly for a 2 year period to
record the development of cardiac complications defined by a broad composite that included
cardiac death and nonfatal myocardial infarction. Cardiac composite including: all-cause
mortality, acute myocardial infarction, unstable angina, congestive heart failure, new
atrial or ventricular dysrhythmia requiring treatment, and cerebrovascular insult.
Information will be collected at 1, 3, 6, 12, 18 and 24 months after surgery.

Outcome measures and postoperative complications including nausea and vomiting will be
recorded by an assessor blinded to the treatment allocation.

Patients will be randomly allocated to one of two treatment groups on the day of surgery
using a computer generated assignment. Group D will receive desflurane and group P will
receive propofol.

Inclusion Criteria:

- Age > 65 years old

- Body mass index > 30 kg/m2

- Undergoing primary total knee arthroplasty surgery

- American society of anesthesiology classification II-III

Exclusion Criteria:

- Patient refusal to participate in the study

- Patient refusal or failure of regional block

- Patients with preexisting neuro-cognitive disorders

- Known intolerance to any of the drugs to be used according to the study protocol
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Stanford, California 94305
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