Clinical trial NCT01225185: Assessing Cerebral Blood Flow Autoregulation During Surgery in the Head-up Position
Official title: Assessing Cerebral Blood Flow Autoregulation in the Head-up Versus Supine Position During General Anesthesia and Its Relationship With Postoperative Neurocognitive Changes and Serum Biomarkers of Brain Injury
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Shouldersurgery
Keywords: neurological complications
brain blood flow autoregulation
Lead sponsor: Johns Hopkins University
Sponsor class: OTHER
Collaborators: name: National Heart, Lung, and Blood Institute (NHLBI)
name: Anesthesia Patient Safety Foundation
First posted: 2010-10-20
Enrollment: 240
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_CONTROL
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: 120 patients undergoing shoulder surgery in the supine lateral position and 120 subjects undergoing surgery in the beach chair position.

Brief summary: Neurological injury after elective shoulder surgery in the beach chair position is thought to result from cerebral hypoperfusion and should therefore be preventable by appropriate hemodynamic monitoring and management. This proposal will use a system to continuously monitor cerebral blood flow autoregulation to identify safe arterial blood pressure targets in patients in the beach chair position, compared with a control cohort having orthopedic surgery in the lateral decubitus supine position. Autoregulation data will be compared against a new, highly specific and sensitive serum biomarker of neurologic injury, glial fibrillary acid protein, and postoperative neurocognitive testing results.

Detailed description: Neurologic injury under general anesthesia in the beach chair position is believed to result from cerebral hypoperfusion.1 We hypothesize that brain hypoperfusion in this circumstance is caused by blood pressure monitoring that does not reflect of cerebral perfusion pressure. Maintenance of arterial blood pressure above an individual's lower limit of cerebral blood flow autoregulation would prevent this devastating complication. Near infrared spectroscopy can be used to continuously monitor autoregulation with the cerebral oximetry index (COx), a moving linear correlation coefficient between cortical tissue oxygen saturation and arterial pressure. We hypothesize that subjects in the beach chair position have impaired cerebral blood flow autoregulation compared with subjects undergoing surgery in the lateral decubitus supine position. We will test this hypothesis by comparing CBF autoregulation data, including the percentage of time patients undergoing elective surgery have abnormal autoregulation, in the beach chair position versus supine position. We will establish the range of arterial pressure required to maintain autoregulation in the two groups. Cerebral autoregulation results will be assessed for a relationship with postoperative neurocognitive dysfunction and with serum glial fibrillary acid protein levels, a biomarker of brain injury.

The specific aims of this study are:

1. To compare the average cerebral oximetry index and the percentage of time with abnormal COx between subjects in the head up or supine position during surgery under general anesthesia.
2. To compare the range of arterial blood pressure required for a normal cerebral oximetry index between subjects anesthetized in the head up or supine position.
3. To assess the association between impaired cerebral blood flow autoregulation and postoperative neurocognitive decline 1 month after surgery and perioperative elevation of serum glial fibrillary acid protein.

Monitoring autoregulation non-invasively with COx has the potential to improve patient safety by delineating individualized limits of safe ABP for patients at risk of neurologic injury.

Eligibility criteria: Inclusion Criteria:

* Patients 18 years old or older undergoing shoulder arthroscopy in the beach chair position or lateral decubitus position without elevation of the head.

Exclusion Criteria:

* Women of child bearing potential require a negative urine HCG test to be enrolled. Patients unable to attend postoperative cognitive testing sessions will be excluded from the study as will those with known allergy to adhesive tape.

Primary outcomes:
measure: cerebral oximetry index between subjects in the head up or supine position during surgery under general anesthesia
timeFrame: During surgery
Secondary outcomes:
measure: To compare the range of arterial blood pressure required for a normal cerebral oximetry index between subjects anesthetized in the head up or supine position.
timeFrame: During surgery
measure: To assess the association between impaired cerebral blood flow autoregulation and postoperative neurocognitive decline and elevation of serum glial fibrillary acid protein.
timeFrame: 1 month after surgery for neurocognitive decline; perioperatively for serum GFAP levels.
Other outcomes:
Locations:
city: Baltimore
country: United States
facility: The Johns Hopkins Hospital
state: Maryland
Study officials:
affiliation: The Johns Hopkins Medical Institutions
name: Charles W Hogue, MD
role: PRINCIPAL_INVESTIGATOR
References: