Cerebrovascular assessment of patients undergoing shoulder surgery in beach chair position using a multiparameter transcranial Doppler approach.

Robba, Chiara 
Matta, Basil 
Tytherleigh-Strong, Graham 
Kang, Niel 

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Although the beach-chair position (BCP) is widely used during shoulder surgery, it has been reported to associate with a reduction in cerebral blood flow, oxygenation, and risk of brain ischaemia. We assessed cerebral haemodynamics using a multiparameter transcranial Doppler-derived approach in patients undergoing shoulder surgery. 23 anaesthetised patients (propofol (2 mg/kg)) without history of neurologic pathology undergoing elective shoulder surgery were included. Arterial blood pressure (ABP, monitored with a finger-cuff plethysmograph calibrated at the auditory meatus level) and cerebral blood flow velocity (FV, monitored in the middle cerebral artery) were recorded in supine and in BCP. All subjects underwent interscalene block ipsilateral to the side of FV measurement. We evaluated non-invasive intracranial pressure (nICP) and cerebral perfusion pressure (nCPP) calculated with a black-box mathematical model; critical closing pressure (CrCP); diastolic closing margin (DCM-pressure reserve available to avoid diastolic flow cessation); cerebral autoregulation index (Mxa); pulsatility index (PI). Significant changes occured for DCM [mean decrease of 6.43 mm Hg (p = 0.01)] and PI [mean increase of 0.11 (p = 0.05)]. ABP, FV, nICP, nCPP and CrCP showed a decreasing trend. Cerebral autoregulation was dysfunctional (Mxa > 0.3) and PI deviated from normal ranges (PI > 0.8) in both phases. ABP and nCPP values were low (< 60 mm Hg) in both phases. Changes between phases did not result in CrCP reaching diastolic ABP, therefore DCM did not reach critical values (≤ 0 mm Hg). BCP resulted in significant cerebral haemodynamic changes. If left untreated, reduction in cerebral blood flow may result in brain ischaemia and post-operative neurologic deficit.

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Beach chair position, Cerebral autoregulation, Non-invasive intracranial pressure, Transcranial Doppler, Adolescent, Adult, Aged, Aged, 80 and over, Anesthesia, Arterial Pressure, Blood Flow Velocity, Brain, Brain Ischemia, Cerebrovascular Circulation, Female, Hemodynamics, Humans, Male, Middle Aged, Monitoring, Physiologic, Oxygen, Patient Positioning, Propofol, Risk, Shoulder, Sitting Position, Ultrasonography, Doppler, Ultrasonography, Doppler, Transcranial, Young Adult
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J Clin Monit Comput
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Springer Science and Business Media LLC
ICM+ software is licensed by the University of Cambridge, Cambridge Enterprise Ltd. MC and PS have a financial interest in a part of its licensing fee. The procedure of non-invasive ICP assessment is distributed as a plug-in for ICM+ monitoring software. BS and MC have financial interest in its licensing fee. The remaining authors declare no conflict of interest. Cambridge Commonwealth, European & International Trust Scholarship, University of Cambridge provided financial support in the form of Scholarship funding for DC. Woolf Fisher Trust provided financial support in the form of Scholarship funding for JD. NIHR Brain Injury Healthcare Technology Co-operative, Cambridge, UK, provided financial support in the form of equipment funding for DC and MC. The sponsors had no role in the design or conduct of this manuscript.