Cerebral Oxygenation in Total Hip Arthroplasty Patients

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.

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.