10-minute topic on neuroprotection during cerebral aneurysm surgery
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10-minute topic on neuroprotection during cerebral aneurysm surgery
- 1. 10-minute topic by R1 Kulchaya Thitayaporn NEUROPROTECTION DURING CEREBRAL ANEURYSM SURGERY
- 2. • Surgical clips obliterating aneurysm Open Craniotomy • Coil embolization of aneurysm Endovascular Surgery CEREBRAL ANEURYSM SURGERY
- 3. Ischemia Uncontrolled release of glutamate Excessive stimulation of postsynaptic receptors Excitotoxicity Neuronal injury and apoptosis MECHANISM
- 5. BLOOD PRESSURE • High CPP augments collateral blood flow to ischemic penumbraCPP • maintain MAP close to pre-SAH baselineChronic HT • maintain MAP 70 – 80mmHg General population
- 6. Keep normocapnia Hypercapnia Vasodilation in non-injured area Intracerebral steal phenomenon Hypocapnia Increase ischemic damage PARTIAL PRESSURE OF CARBON DIOXIDE
- 7. Hyperglycemia Increase damage in focal ischemia Independent predictor of poor outcomes in focal ischemic injury Incomplete ischemia >>> anaerobic glycolysis >>> lactic acid >>> ROS >>> neuronal necrosis Avoid glucose containing solutions Treat hyperglycemia aggressively: keep < 180mmol/L BLOOD GLUCOSE
- 8. Hypothermia Decrease CMRO2 Effects ischemic cascade Suppression of glutamate release Decrease NO- production Neuroprotective in global and focal ischemia Greatest effect at 18 – 22˚C via CPB 32 – 35˚C still controversial Shivering >>> increase O2 demand, arrhythmia, cardiac ischemia, coagulopathy, increase infection rate, delayed emergence Hyperthermia >>> poor outcome TEMPERATURE
- 9. IV ANESTHETIC AGENTS Anesthetics CBF CMRO2 ICP Thiopental Propofol Etomidate Ketamine - / Midazolam - / Fentanyl - / - / - /
- 10. CMRO2 reduction Dose dependent EEG depression Inhibit glutamate release and postsynaptic glutamate receptor- mediated responses Halothane Potent cerebral vasodilator Enflurane Potent CMRO2 reduction Enflurane + hypocarbia = seizure activity Isoflurane, Desflurane Least potent cerebral vasodilators IICP minimized with hyperventilation Sevoflurane Long-term protection in focal ischemia INHALATION ANESTHETIC AGENTS
- 11. INHALATION ANESTHETIC AGENTS Anesthetics CBF CMRO2 Autoregulation Halothane Isoflurane / Desflurane / Sevoflurane / N2O /
- 12. • Slight increase in regional CBF • Keep CVP 10 – 12mmHg Hypervolemia • Slight increase in regional CBF • Keep Hct 30 – 35% Hemodilution • Significant increase in regional CBF and brain tissue oxygenation • Keep SBP 160 – 200 if clipped, 120 – 150 if unclipped Hypertension “TRIPLE-H” THERAPY
- 13. THANK YOU FOR YOUR ATTENTION
Editor's Notes
- Modify intracellular and vascular biological responses Increase tissue tolerance to ischemia/reperfusion
- ห่วง transmural pressure (= CPP = MAP – ICP or CVP) ถ้า MAP สูงไปก็ไม่ดี, ICP ต่ำไปก็ไม่ดี เพราะ transmural pressure สูงจะทำให้แตกได้ง่าย High cpp >>> minimize secondary injury, and result in improved neurological outcome Collateral: circle of willis, pial-to-pial, leptomeningeal pathways
- “steal” by preferentially vasodilating vessels in the noninjured area and decreasing intracellular pH
- Spontaneous hyperthermia, common in the postischemic brain, is associated with poor outcome in humans and should be treated aggressively.
- Thiopental = induction of choice Propofol = aggravate glutamate excitotoxicity Etomidate = ยาดี แต่สาร propylene glycol ที่ผสมอยู่อาจทำให้ cerebral tissue hypoxia, acidosis >>> ควรหลีกเลี่ยง Barbiturates Decrease CMRO2 Decrease EEG activity CBF redistribution to peri-ischemic area Free radical scavenging Block glutamate receptors Slow adenosine 5-triphosphate depletion Potentiate γ-aminobutyric acid activity Propofol Decreases CMRO2 & CBF Inhibits glutamate release Free radical scavenging Large dose may decrease CPP propofol has negative inotropic and vasodilatory properties, it may decrease CPP if a large dose is administered rapidly Etomidate Decrease CMRO2, CBF Be aware of propylene glycol Ketamine Increases ICP, CMRO2, CBF No data on neuroprotection Opiods Cerebral vasodilation Increases CBF No data on neuroprotection
- Halothane: Hyperventilation can be used to prevent this increase but must be instituted before introducing the halothane, as the vasodilatory effects occur faster than the onset of metabolic suppression
- N2O IICP, impairs cerebral autoregulation >>> AVOID
- Vasospasm = major cause of morbidity and mortality following SAH = free subarachnoid blood under high pressure comes into contact with the surfaces of vessels >>> Constriction of the cerebral arterial vasculature occurs esp in basal cisterns Triple-H augments CBF Prevents delayed ischemia Improves clinical outcome Hypervol. Keep CVP 10 – 12, isotonic fluids with sodium to avoid hyponat. Hct 30 – 35% SBP 160 – 200 if clipped, 120 – 150 if unclipped Nimodipine: CCB