Cerebral Blood Flow Evaluation With Trancranial Doppler After Interscalene Nerve Block (CBF-TCD)

Cerebral Blood Flow Evaluation With Trancranial Doppler After Unilateral Interscalene Nerve Block: Observational Prospective Study

The purpose of this study is to assess cerebral blood flow velocity (CBFV) following regional anesthesia for shoulder surgery. The results of this study will help to further understand the physiologic effect of the interscalene nerve block on cerebral blood flow.

Study Overview

• Status: Terminated
• Conditions: Cerebral Blood Flow; Horner Syndrome; Regional Anesthesia
• Intervention / Treatment: Device: TCD Measurement

Detailed Description

Traditionally, cerebral blood flow (CBF) is believed to decline when mean arterial pressure (MAP) is below the lower limit of cerebral autoregulation. Cerebral blood flow autoregulation refers to the capacity of the central nervous system to maintain blood flow within a wide range of mean arterial blood pressure.

The habitual thinking is that the brain is perfused merely dependent by the blood pressure and that above or below the limits of cerebral autoregularion CBF is pressure passive. Despite this notion, there is evidence showing that parameters other than MAP influence cerebral hemodynamics independent of cerebral autoregulation. One of the physiologic processes that contribute to CBF regulation is cardiac output (CO). However, exactly how an alteration in CO, in the face of a stable blood pressure, leads to a change in CBF is not entirely clear.

One of the suggested mechanisms in play is the sympathetic nervous system (SNS)-mediated vasoconstriction of extracranial and proximal intracranial vessels. Cerebral arteries are abundantly innervated by sympathetic nerve fibers originating from the superior cervical ganglion. Studies have shown that CBF reduction is attenuated by pharmacologic blockade or extirpation of the cervical sympathetic chain.

The anesthetic protocol for patients undergoing major shoulder surgery include an interscalene nerve block (ISNB) combined with general anesthesia in the sitting position. The ISNB involves injecting local anesthetic at the level of the cervical spinal roots. One of the most common side effects encountered after ISNB is Horner syndrome, which is characterized by ptosis, myosis, and enopthalmia. Horner's syndrome results from the diffusion of the local anesthetic solution to the ipsilateral sympathetic cervical chain (stellate ganglion). The presence of Horner's syndrome indicates spread of local anesthetic to the sympathetic chain.

Whether this degree of sympatholytic following interscalene block is associated with an observable change in CBF is unknown. Studies in baboon have shown that cervical surgical sympathectomy maintained CBF in the face of hemorrhagic hypotension and CBF did not decrease until MAP was 35% of the baseline value. These results suggest that sympathectomy induced by the block of the sympathetic chain by the local anesthetic injected for the ISNB might alter CBF. Therefore, the aim of our study is to evaluate the effect of unilateral interscalene nerve block on CBF by measuring CBF velocity non-invasively with Transcranial doppler (TCD).

• Study Type: Observational
• Enrollment (Actual): 10

Contacts and Locations

Study Locations

• United States
  • California
    • Stanford, California, United States, 94304
      • Stanford University School of Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients undergoing orthopedic surgery with an indication for preoperative insertion of interscalene nerve block, aged 18-85 years old, and give consent to participating in study.

Description

Inclusion Criteria:

• Patients undergoing orthopedic surgery and with an indication for preoperative insertion of interscalene nerve block
• 18-85 years old
• Give consent to participate in study

Exclusion Criteria:

• Cannot give consent
• Patients who are clinically unstable or require urgent/emergent intervention

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Treatment Arm; Patients ages 18-85 years old presenting with orthopedic shoulder surgery with indication to receive preoperative insertion of interscalene nerve block.	Device: TCD Measurement; CBFV measurements will be acquired continuously with the patient supine and the head neutral. Analysis of CBFV measurements will be undertaken at 3 timepoints: Patient awake and supine in the holding area; After sedation; After interscalene nerve block

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cerebral Blood Flow Velocity before and after interscalene nerve block	The TCD automatically measures blood flow velocity in the main cerebral arteries of the circle of Willis. We will target the MCA which is the closest to the temporal bone therefore the most easily accessible for insonation and monitoring. We will do a bilateral monitoring.	baseline, after 30 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Systolic, diastolic, mean blood pressure changes before and after interscalene nerve block	Will be measured before/during/after interscalene nerve block placement	baseline, after 30 minutes
Heart Rate	Will be measured before/during/after interscalene nerve block placement	baseline, after 30 minutes
Respiratory Rate changes before and after interscalene nerve block	Will be measured before/during/after interscalene nerve block placement	baseline, after 30 minutes
EtCO2 changes before and after interscalene nerve block	Will be measured before/during/after interscalene nerve block placement	baseline, after 30 minutes
SpO2 changes before and after interscalene nerve block	Will be measured before/during/after interscalene nerve block placement	baseline, after 30 minutes
Type of local anesthetic	Local anesthetic characteristics will be collected after interscalene block placement.	30 minutes after the nerve block
Position of the needle on the cervical trunk for interscalene nerve block	Needle position for interscalene nerve block insertion will be assessed at the time of interscalene block placement	Baseline
Volume of of local anesthetic	Local anesthetic characteristics will be collected after interscalene block placement.	30 minutes after the nerve block
Concentration of local anesthetic	Local anesthetic characteristics will be collected after interscalene block placement.	30 minutes after the nerve block

Collaborators and Investigators

• Sponsor: Stanford University

Publications and helpful links

General Publications

• Meng L, Hou W, Chui J, Han R, Gelb AW. Cardiac Output and Cerebral Blood Flow: The Integrated Regulation of Brain Perfusion in Adult Humans. Anesthesiology. 2015 Nov;123(5):1198-208. doi: 10.1097/ALN.0000000000000872.
• Drummond JC. Cardiac Output: The Neglected Stepchild of the Cerebral Blood Flow Physiology Family. J Neurosurg Anesthesiol. 2020 Apr;32(2):93-94. doi: 10.1097/ANA.0000000000000677. No abstract available.
• ter Laan M, van Dijk JM, Elting JW, Staal MJ, Absalom AR. Sympathetic regulation of cerebral blood flow in humans: a review. Br J Anaesth. 2013 Sep;111(3):361-7. doi: 10.1093/bja/aet122. Epub 2013 Apr 24.
• Fitch W, MacKenzie ET, Harper AM. Effects of decreasing arterial blood pressure on cerebral blood flow in the baboon. Influence of the sympathetic nervous system. Circ Res. 1975 Nov;37(5):550-7. doi: 10.1161/01.res.37.5.550.
• Seltzer JL. Hoarseness and Horner's syndrome after interscalene brachial plexus block. Anesth Analg. 1977 Jul-Aug;56(4):585-6. doi: 10.1213/00000539-197707000-00033. No abstract available.

Study record dates

Study Major Dates

• Study Start (Actual): March 4, 2021
• Primary Completion (Actual): May 19, 2021
• Study Completion (Actual): July 30, 2021

Study Registration Dates

• First Submitted: November 2, 2020
• First Submitted That Met QC Criteria: November 18, 2020
• First Posted (Actual): November 24, 2020

Study Record Updates

• Last Update Posted (Actual): September 16, 2021
• Last Update Submitted That Met QC Criteria: September 14, 2021
• Last Verified: September 1, 2021

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nervous System Diseases; Eye Diseases; Neurologic Manifestations; Autonomic Nervous System Diseases; Miosis; Pupil Disorders; Horner Syndrome
• Other Study ID Numbers: 59007

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No