Cerebral Oxygenation in Total Hip Arthroplasty Patients

Study Overview
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Brief Summary
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We plan to investigate the relationship between hypotensive epidural anesthesia for hip arthroplasty and cerebral oxygen saturation.

Detailed Description
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The relationship between cerebral oxygenation and blood pressure in patients undergoing hypotensive epidural anesthesia has not been completely elucidated. Previous publications have demonstrated a low incidence of post-op cognitive dysfunction in patients undergoing hypotensive epidural anesthesia for total hip replacement (1-3) and that cerebral blood flow velocity is preserved as measured by transcranial Doppler (4). An earlier investigation by Dr. Yadeau demonstrated infrequent cerebral oxygen desaturation in spontaneously breathing patients undergoing shoulder arthroscopy, even in the presence of hypotension (4), but did not investigate outcomes in the cognitive domain or have a control group of patients undergoing surgery with general anesthesia. There has only been one study looking at cerebral oxygenation and hip surgery, which was performed in elderly patients with fractures. It demonstrated that patients with low pre-op regional cerebral oxygen saturation (rSO2) had higher incidence of delirium (5) but many of those patients had surgery under general anesthesia. Given the costs associated with post-op delirium, cognitive dysfunction and stroke (6) and based on the fact that previous publications from this institution have demonstrated both a low incidence of cognitive dysfunction and preservation of cerebral blood flow velocity using this anesthetic technique, we hypothesized that cerebral oxygen desaturation will not occur in this population.

Official Title
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Cerebral Near-Infrared Spectroscopy and Hypotensive Anesthesia in Patients Undergoing Total Hip Arthroplasty

Conditions
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Cerebral Oxygen Desaturation, Post-operative Delirium

Intervention / Treatment
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* Device: Cerebral Oximeter


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients 18-80 years old undergoing unilateral total hip arthroplasty Hypotensive epidural anesthesia Exclusion Criteria: Contraindication to controlled hypotension and/or neuraxial anesthesia. Severe pulmonary hypertension or pre-op systolic blood pressure reading >150 mm Hg Moderate to severe valvular stenosis. History of stroke, dementia, or post-op delirium Prior OSA diagnosis History of benzodiazepine use (regular use for longer than 3 months) Chronic renal or hepatic disease (renal failure, history of liver failure, cirrhosis) History of alcoholism or heavy alcohol intake (defined as averaging more than 3 drinks per night; recovery is OK) Parkinson's disease Severe chronic pulmonary disease Total anterior hip approach being used Hip resurfacing procedure Non-English Speaking* Questionnaires being used to assess mental status are only validated in English.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: THA Patients<br>Patients undergoing unilateral total hip arthroplasty | Device: Cerebral Oximeter<br>* Use of cerebral oximeter to monitor cerebral oxygenation for occurence of desaturation events.<br>* Other names: oximeter;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxygen Desaturation Incidences | The number of participant's experiencing an intra-operative cerebral oxygen desaturation event. Measured in the number of patients, beginning with the time the patients' enters the operating room and up to 4 hours. | Intra-operation (when the patient enters the operating room, up to 4 hours) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Duration of Oxygen Desaturation | Duration of cerebral oxygen desaturation | Intra-op ( during the time the patient is in the operating room, up to 4 hours) | 
| Presence of Post-operative Delirium | The number of patients who have post-operative delirium, as determined by counting the patients who suffer from this condition. Although recorded at various time points, the total number of participants experiencing post-operative delirium was summed and reported. | Post-op Day 1, Post-op Day 2 | 
| Patients With Cognitive Dysfunction | The number of patients considered to experience cognitive dysfunction as identified by low scores on the mini-Cog. The Mini-Cog checks for the brain function (or the cognitive impairment) of the participant. The Mini-Cog does this by examining a patient's ability in two areas. This is done via a three-word recall test and the Clock Drawing Test. Three-Word Recall The Clock Drawing Test (CDT) There are five total points a person can score on the Mini-Cog: Give one point for each word that was correctly remembered. (0-3 points) Give two points for a correctly drawn clock, meaning the numbers are in roughly the correct locations and two hands are pointed to the 11 and the 2. The length of the hands does not matter. (0 or 2 points) If a patient scores less than three points, they are counted as experiencing cognitive dysfunction. Although collected across different time points, the total number of patients scoring less than 3 points were summed and reported. | Post-op Day 1, Post-op Day 2 |