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Neuroanaesthesia update
This document provides an overview and update on issues in neuroanesthesia. It discusses recurrent issues such as patient positioning, monitoring, fluid management and more that have not changed significantly over time. It also reviews cerebral physiology concepts like blood flow regulation and the effects of anesthetic agents. The document outlines current surgical trends like minimally invasive procedures and equipment trends like intraoperative CT. It concludes by emphasizing the importance of multidisciplinary team training to continually improve neuroanesthesia care.
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Neuroanaesthesia update
- 1. UPDATE IN NEUROANAESTHESIA DOUGLASFAHLBUSCH MBBS, FANZCA, GDM, GAICD WWW.PERIOPERATIVE.COM.AU Improving cost, risk and the healthcare experience MAY 2015 1
- 2. INTRODUCTION • Neuroscience underpins •Neuroanaesthesia and • Neurocritical care • ‘… advance the art and science of the care of the neurologically impaired patient through education, training and research in perioperative neuroscience’ 2 SNACC, RCOA
- 3. OVERVIEW PRACTICAL UPDATE • Brain:defines who we are • Loss of function defines death • Function routinely manipulated in anaesthesia • Critical considerations when operating on this target organ Gelb AW 2015 • What’s not new • Surgical trends • Cerebral oximetry • Intraoperative CT • Pursuit of excellence 3
- 4. RECURRENT ISSUES WHAT’S NOTNEW • Patient positioning • Neurophysiologic monitoring • Intravenous fluid management • Arterial blood pressure target • PaCO2 target • Hypothermia • Control of intracranial pressure/ brain relaxation • Use of steroids • Use of osmotherapy Miller 8th Edn, Ch 70 • Use of diuretics • Use of anticonvulsants • Pneumocephalus • Venous air embolism • Glucose management • Emergence from anaesthesia 4
- 5. WHAT’S NOT NEW CEREBRALPHYSIOLOGY • Cerebral metabolic rate (CMR) is high: • 60% function, 40% cellular homeostasis • 15% of cardiac output • Cerebral blood flow (CBF) is ~50 mL/100 g/min • grey 80%, white 20% • CBF and local metabolism highly coupled over MAP 65- 150 mmHg (est), else passive 5Miller 8th Edn, Ch 17
- 6. WHAT’S NOT NEW CBFAUTOREGULATION • Chemical regulation • PaCO2 range of 25 to 70 mm Hg direct effect on CBF • PaO2 < 60 mm Hg CBF decreases dramatically • Temperature affects metabolic rate primarily, CBF secondarily • Systemic vasodilators affect the cerebral circulation and can, depending on the MAP, increase CBF • Vasopressors affect arterial blood pressure - CBF secondarily 6Miller 8th Edn, Ch 17
- 7. WHAT’S NOT NEW SELECTIONOF ANAESTHETICS • Intravenous • Barbiturates, etomidate, and propofol decrease the CMR • Opiates and benzodiazepines effect minor decreases in CBF and CMR • Ketamine can significantly increase the CMR and therefore CBF • Volatiles reduce CMR • above 1 MAC increase CBF • reduce/ omit if brain ‘tight’ 7Miller 8th Edn, Ch 17
- 8. WHAT’S NOT NEW CEREBRALISCHAEMIA • Barbiturates, propofol, ketamine, volatile anaesthetics, xenon neuroprotective • animal models, mild ischaemic insult • not with moderate-to-severe injury (delays apoptosis) • Etomidate can decrease regional blood flow, can exacerbate ischaemia • Brain stores of O2/ substrates limited, extremely sensitive to decr CBF • Severe decreases in CBF = rapid neuronal death • early excitotoxicity, and delayed apoptosis 8Miller 8th Edn, Ch 17
- 9. CONTROL OF INTRACRANIAL PRESSURE/BRAIN RELAXATION Miller 8th Edn, Table 70-1 & Box 70-3 (often overlooked) JVP -> AWP -> PCO2 & O2 -> ABP -> CMRO2 -> vasodilators -> mass lesions 10
- 10. SURGICAL TRENDS • Minimallyinvasive procedures • Transphenoidal • DBS • Intraventricular • Discectomy 11
- 11. GUIDELINES FOR PERCUTANEOUS ENDOSCOPIC SPINALSURGERY • Lumbar, Thoracic, Cervical disc herniations • Lateral spinal canal/ foraminal stenoses • Degen facet joint cysts with radiculopathy • Symptomatic central stenosis (experienced hands) • C/I • Cauda equina • Instabilities/ deformities/ non-neural back pain • Very large herniations relatively C/I ISMISS 2010 12
- 12. TRANSFORAMINAL ENDOSCOPIC DISCECTOMY MichaelY Wang, MD FACS; Professor, Departments of Neurological Surgery & Rehab Medicine, University of Miami Miller School of Medicine 13
- 13. ENDOSCOPIC SPINAL SURGERY •Duration 45-80 mins, • LA 1.9 mg/kg • ‘Discomfort’ - ok if nerve roots avoided • Discharge < 24 hrs possible (Chan) 14 Surg Neurol Int. 2014; 5(Suppl 3): S62–S65
- 14. ENDOSCOPIC SPINAL SURGERY • LA/sedation has been used since 1926 (Towne) • Well-tolerated (Hsien-Te Chen) • Indicated for multiple comorbidities (Khan), ASA I-IV, geriatrics • Intraop evaluation of surgical progress • Early discharge • The future ‘gold standard’ for discectomy? (Gibson 2012) 15
- 15. DBS STEREOTACTIC SCAN PREOP •> 50 cases (Matthew McDonald, Neurosurgeon Calvary Wakefield) • Propofol/ LA for placing frame (+/- opioid for tremor suppression) • Avoid benzo’s 16 Picture courtesy of A/Professor Wilcox, FMC
- 16. DBS THEATRE SETUP • Dexmedetomidine infusion •Propofol ceased once scalp reflected 17 Picture courtesy of A/Professor Wilcox, FMC
- 17. Picture courtesy ofA/Professor Wilcox, FMC DBS INTRAOP 18
- 18. DBS BATTERY/ LEADS • LMA •Propofol • Fentanyl • Volatile • Battery most commonly right on men and left on women (seatbelts) 19
- 19. EQUIPMENT TRENDS • Cerebraloximetry • Intraoperative CT 20
- 20. INTRACRANIAL MONITORING Near-Infrared oximetry ICP (ventricular orparenchymal) Brain tissue oximetry Jugular venous oximetry Microdialysis 21
- 21. NEAR INFRARED SPECTROSCOPY • Twowavelengths • Substract superficial tissues • Left with deep tissue signal • Non-pulsatile • Ratio of arterial to venous blood dictates ‘saturation’ • Multiple sites (cerebral, kidneys, thigh) 22
- 22. NEAR INFRARED OXIMETRY •Relative indices of perfusion • Baseline set pre- induction (usu. 58-82) • Relative decline < 20% ok • Absolute thresholds • 50 intervene • 40 critical 23 up to 6 channels
- 23. NEAR INFRARED SPECTROSCOPY 24 • Perioperative morbiditynot correlated with cerebral desaturation • Reassurance for • elderly, paeds • vasculopaths • ACDF, carotids Cowie et al 2014 (AIC)
- 24.
- 25. INTRAOP CT USES -DBS • Confirm stimulator placement & track • Exclude bleeding 26
- 26. INTRAOP CT USES -SPINAL FUSION • screw placement • alignment • bleeding 27
- 27. CONCLUSION • Interplay ofCNS with other organ systems/ physiology/ pathology • Unit Excellence: • Staff training, retention • Cross-functional processes (breaking down the silos) • IT: increase reach and engagement • Closed loop delivery systems: anaesthesia, fluids … 28 Puri 2015
- 28. FURTHER INFORMATION • NeuroanaesthesiaSIG - ANZCA/ ASA/ NZSA • Neuroanaesthesia Society of Great Britain and Ireland https://nasgbi.org.uk/ • Royal College of Anaesthetists http://www.rcoa.ac.uk/document- store/guidance-the-provision-of-services-neuroanaesthesia-and- neurocritical-care-2015 • Society for Neuroscience in Anesthesiology and Critical Care http://www.snacc.org/# • Perioperative Solutions www.perioperative.com.au • Dr Douglas Fahlbusch - [email protected] 29
- 29. 1. Gelb AW.Actualización en neuroanestesia. Rev Colomb Anestesiol. 2015;43:1-2. 2. Gibson JNA, et al. Transforaminal endoscopic spinal surgery: The future ‘gold standard’ for discectomy? A review, The Surgeon (2012) 3. Hsien-Te Chen et al. Endoscopic discectomy of L5-S1 disc herniation via an interlaminar approach: Prospective controlled study under local and general anesthesia. Surg Neurol Int. 2011; 2: 93. 4. Khan MB et al. Thoracic and lumbar spinal surgery under local anesthesia for patients with multiple comorbidities: A consecutive case series. Surg Neurol Int. 2014; 5(Suppl 3): S62– S65. 5. Li ZZ et al. The strategy and early clinical outcome of full-endoscopic L5/S1 discectomy through interlaminar approach. Clin Neurol Neurosurg. 2015 Mar 14;133:40-45 6. Miller RD (Ed). Miller’s Anesthesia. 8 Edn. Reed Elsevier 2014 7. Peng CWB et al. Percutaneous endoscopic lumbar discectomy: clinical and quality of life outcomes with a minimum 2 year follow-up. Journal of Orthopaedic Surgery and Research 2009, 4:20 8. Puri et al. A Multicenter Evaluation of a Closed-Loop Anesthesia Delivery System: A Randomized Controlled Trial.Anesth Analg. 2015 Apr 21 9. Towne EB. Laminectomy and removal of spinal cord tumors under local anesthesia. Cal West Med. 1926;24:194. References 30
Editor's Notes
- #4 Everyone is a ‘part-time neuroanaesthetist’
- #6 Total body blood flow 7-8 ml/ 100g/ min (5500/700(100g)/min Autoregulation assumes venous pressure normal
- #8 Cl- channel blocked by frusemide
- #9 (< 6-10 mL/100 g/min) ie ~ average body BF
- #11 Table is inverse pyramid JVP -> Head up, kinked neck, tight ties/ collars AWP -> ETT, obstruction/ spasm/ strain/ PTX/ PEEP PCO2 & O2 -> Further reduction of Pa co 2 (to not <23-25 mm Hg) ABP -> CMRO2 -> Pain/arousal/ Seizures/ Febrile? -> propofol (?) & barbiturates vasodilators -> N 2 O, volatile agents, nitroprusside, calcium channel blockers mass lesions - Hematoma/ Air ± N 2 O/ CSF (clamped ventricular drain) -> ventriculostomy, brain needle
- #12 require a new understanding of the surgical approaches, needs and complications where the entire procedure is done with video or other imaging guidance
- #13 International Society for Minmal Intervention in Spinal Surgery www.ismiss.com (USA/ Europe)
- #16 Gibson JNA, et al., Transforaminal endoscopic spinal surgery: The future ‘gold standard’ for discectomy? e A review, The Surgeon (2012), doi:10.1016/j.surge.2012.05.001
- #18 Load 1 mcg/kg (?), maint. 0.2-1.0 mcg/kg/hr 1. Rozet el al. Clinical Experience with Dexmedetomidine for Implantation of Deep Brain Stimulators in Parkinson’s Disease. IARS 103 (5): Nov 2006
- #19 Load 1 mcg/kg (?), maint. 0.2-1.0 mcg/kg/hr 1. Rozet el al. Clinical Experience with Dexmedetomidine for Implantation of Deep Brain Stimulators in Parkinson’s Disease. IARS 103 (5): Nov 2006
- #22 Schematic of available intracranial monitoring, with near-infrared oximetry (NIRS), intracranial pressure (ICP, either by ventriculostomy or parenchymal probe), brain tissue oximetry (Pb o 2 ), microdialysis, and jugular venous oximetry (Sj o 2 ).
- #24 Covidien Invos
- #25 Nonin
- #29 society for neuroscience in anaesthesia and intensive care
- #30 https://nasgbi.org.uk/
- #31 Li - 72 cases Khan - 7 cases - Five patients had interlaminar decompressions for stenosis alone, while two patients had laminectomies for debulking of tumors. The mean duration of surgery was 79.8 ± 16.6 min, the mean estimated blood loss was 157.1 ± 53.4 ml, the mean dose of local anesthetic was 1.9 ± 0.7 mg/kg, and the mean length of hospital stay after surgery was 3.2 ± 1.2 days. There were no intraoperative complications. The surgery resulted in improved VAS and ODI scores consistent with significant improvement in pain (P = 0.017) and functionality (P = 0.011).