Neuro II Flashcards
1
Q
Preoperative evaluation for neuro surgery?
A
- Underlying medical conditions
- Ex: Patent Foramen ovale- specific for sitting position/high risk VAE (sx near dural sinus)
- Procedure length and position
- Question optimized for surgery
- Ex: subarachnoid hem, trauma pts → on mannitol, 3% NS, blood products
- Negotiate hemodynamic/ventilation & position goals with surgeon
-
Determine need for:
- Abx
- Steroids- only for tumors (normalize edema ring → improve outcomes)
- Diuretics
- Bolus mannitol/3% NS prior to start
- Anticonvulsants- Prophylactic admin
- Common w/ trauma (brain exposed to blood)/brain tumors
- Ex: phenytoin, phenobarb
- Common w/ trauma (brain exposed to blood)/brain tumors
- Carefully assess fluid and electrolyte status – correct pre-op
- Glucose levels: 90-180 mg/dL in diabetic patients
- Avoid changes in Na+ > 3-4 mEq/L per hour (central pontine myelinolysis)
- Plt count >100,000mm3
2
Q
Considerations for neuro assssment?
A
where are they on compliance curve?
- Level of consciousness
- Awake/alert → can tolerate extra volume
- ICP
- Headache
- Nausea
- Papilledema
- pupil size
- respiratory pattern
- any ICP issues → TIVA (propofol) approach
- avoid hypoventilation/CO2 increase
- Neurological deficits
- Ex: look at brain – is it bulging?
- MRI or CT results
- Location of lesion
- Surgeon’s impression of intracranial compliance and VAE risk
- Supratentorial disease= ICP mgmt. problems
- Infratentorial lesions = mass effects on vital brain stem structures w/ elevated ICP d/t obstructive hydrocephalus
- ICP derangements can be identified radiologically – “slit ventricles” or shift in midline brain structures of more than 5mm – advanced pathology
3
Q
Interventional neuroradiology uses, benifts, risks?
A
- Emerging as the standard of care in some populations
- International Subarachnoid Aneurysm Trial – meta analysis support widespread use of the this approach
- most now repaired this way
- *Grade 1 & 2 → better outcomes than open repairs
-
Uses: Angiography & embolization/devascularization of aneurysms, AVMs, brain tumors & spinal cord lesions
- Technique: Insertion of occlusive material (detachable platinum coils, cyanoacrylates, “Onyx liquid embolic system,” & polyvinyl alcohol particles
- Vasospasm treatment, Balloon angioplasty, thrombectomy (acute stroke), or endovascular stenting of occlusive cerebrovascular disease & extracranial carotid disease (often anti-plt therapy 5-7 days pre)
- International Subarachnoid Aneurysm Trial – meta analysis support widespread use of the this approach
- IR benefits:
- Lower risk infection
- Lower 3rd spacing
- IR risks:
- Sudden hemorrhage → space occupying lesion/hematoma
- Stents/coils deployed to wrong place → occlusive
- Vascular injury
-
Open procedures necessary:
- Wide neck aneurysm
- Abnormal anatomy
- Disease/occluded vessels → cant pass catheters
4
Q
Goals of neuro interventional radiology?
A
- GA not always required
- conscious sedation often appropriate depending on procedural complexity
- GA: TIVA vs VA (dep on intracranial compliance)
- Sedation: fentanyl, midaz, propofol, precedex
- Precedex issues:
- Interfere w/ cog testing
- HoTN
- Precedex issues:
- conscious sedation often appropriate depending on procedural complexity
- Control sedation or anesthetic level for prompt neurologic evaluation
- Choosing → How important for neuro eval and can pt stay still?
-
Keep the patient from moving during the procedure!
- Mapping important
- Have the ability to manipulate cerebral hemodynamics on demand to meet procedural needs
- Ex;
- Alter CO2: Hyper/hypoventilate → change perfusion to certain area in brain
- HyoTN → Use VA, propofol, esmolol, NTG/NTP (stronger)
- Stent Deployment → Expect HoTN and bradycardia (pharmacologic
- Ex;
treatment)
- INR procedures w/ IV sedation:
- Ex: diagnostic angiography, carotid angioplasty and stenting, AVM embolization, etc.
- GA required: intracranial angioplasty, embolization of aneurysms, uncooperative patients, etc.
- Ex: diagnostic angiography, carotid angioplasty and stenting, AVM embolization, etc.
5
Q
Intervnetional neuroradiology procedure considerations? monitors needed?
A
- 6-7 Fr gauge sheath in femoral artery
- Anticoagulation utilized ~ 24 hrs: Heparin
- Need preop baseline coag panel!
-
Dose: 3000-5000 units Heparin + infusion
-
ACT 1.5-2.5 X baseline
- Catheters are foreign bodies → clot!
-
ACT 1.5-2.5 X baseline
- Extensions on ventilation & IV tubing- bed turned 90-180 deg
- Monitors:
-
ETCO2- manipulate for radiologist
- Patho: Lesions = local vasodilation surrounding
- Hyperventilate → vasoconstrict vessels aroung healthy brain to lesion (receiving device)
- Patho: Lesions = local vasodilation surrounding
-
Art BP- manipulate for radiologist
- HoTN → asked when deploying occlusive material/coil/glue (greater control)
- Don’t want HTN d/t pushing occlusive material beyond intended area
- HoTN → asked when deploying occlusive material/coil/glue (greater control)
-
Bilateral LE pulse oximetry
- If use femoral artery → assess vasospasm, thromboembolism, mechanical obstruction
-
ETCO2- manipulate for radiologist
- May have to alter anesthetic plan:
- EEG
- evoked potentials
- transcranial doppler
- awake patient feedback
6
Q
What are some sudden and severe complications in interventional neuroradiology?
A
-
Hemorrhagic –
- Protamine
- Dose: 1 mg per 100 units heparin admin
- Controlled HoTN
- Deepen anesthetic
- Esmolol
- NTG
- NTP
- Protamine
-
Occlusive – device (coil/balloon) deployed to unintended area → worry of ischemic damage distal to occlusion
- Deliberate HTN – enhance collateral flow through CoW.
- BP > 30-40% baseline or until neurologic symptoms resolve
- Phenylephrine
- Dopamine
- BP > 30-40% baseline or until neurologic symptoms resolve
- Direct thrombolysis
- Deliberate HTN – enhance collateral flow through CoW.
-
Anaphylaxis
- Contrast media = anaphylaxis risk
- Admin Epi
- 3rd spacing → have fluids available
- Contrast media = anaphylaxis risk
7
Q
Overall goals for treatment in interventional neuroradiology?
A
-
Overall treatment → Neuroprotective measures
- Hyperventilate – decrease ICP
- ETCO2 26-30 mmHg
- Rapid fluid admin – for hemorrhagic
- Diuretic admin
- Mannitol 0.5 g/kg
- Anticonvulsants
- Phenytoin
- Phenobarb
- induce Hypothermia (33-34 deg C)
- EEG suppression- TPL coma (burst suppression)
- reduce CMRO2 → preserve marginally perfused cells
- Ensuring O2 going to maintenance of cell integrity
- reduce CMRO2 → preserve marginally perfused cells
- HOB 15 deg and neutral
- Hyperventilate – decrease ICP
- Make sure you have access to all of these agents in the event of an emergency because rapid response will be required. Hypothermia to 33-34 degrees C B6th767
- For deliberate hypertension consider phenyephrine or dopamine – get BP 30-40% > than baseline or until neurologic symptoms resolve. For controlled hypotension consider esmolol, NTG or NTP. Dose of protamine is 1mg for each 100U heparin given. Head up 15 degrees and neutral, PaCO2 around 28-30mmHg, give 0.5g/kg mannitol, rapid IV infusion, phenytoin and phenobarbital, TPL coma (burst suppression), temp 33-34C.
8
Q
What are supratentorial tumors? symptoms?
A
Pathophysiology
- Supratentorial – located ABOVE tentorium
- Tentorium: process of dura mater between cerebrum and cerebellum supporting the occipital lobes (cerebellum and occipital lobe)
- Most common for craniotomy
- Ex:
-
Meningiomas-
- large size
- difficult location
- highly vascular → considerable BL
- surgically challenging → lengthy procedure
- Necrotic hemorrhagic core
- Wide border of brain edema
- increased bulk
- increased impaired autoreg area
-
Gliomas (oligodendrogliomas, astrocytomas)
- Easy access location
- Less vascular – less bleeding risk
- Hard to get clear margins → often reoccur (often “Debulking procedures”)
- Metastatic lesions (breast, melanoma, lung, kidney)
-
Chronic subdural hematomas-
- Space occupying lesions → displace other structures (specific symptoms or HA or Sz)
-
Meningiomas-
-
Symptoms:
- ICP problems. Small changes in BP= big changes CBF/ICP
- appear when compensatory mechanisms exhausted by growing lesion
9
Q
Considerations for supratentorial tumors
A
-
Consider tumor location & size (blood loss & surgical position)
- Locations:
- Hypothalamus: SNS disturbance, altered LOC, temp, fluid reg, DI, cerebral salt wasting syndrome
- Dural sinus: concern for VAE
- Low risk except lesions encroaching on sagittal sinus
- Size: Ability to displace structures
- → ICP increase risk → CPP/herniation issues**
- Generally: tumors = vascular
- Necrotic hemorrhagic core
- Wide border of brain edema (ischemic penumbra)
- increased bulk
- increased impaired autoreg area → maintain CPP
- Tx: Steriods 24-48 hrs prior
- stabilize edema ring
- stabilize BBB
- Generally: tumors = vascular
- → ICP increase risk → CPP/herniation issues**
- Locations:
-
VAE risk:
- Low, except lesions encroaching on sagittal sinus
-
Small changes in BP = big changes CBF/ICP
- Impaired autoregulation area near tumor
-
Bilateral Subfrontal approach (retraction/irritation frontal lobes) - “frontal lobey”
-
Consequence of frontal lobe retraction →
- delayed emergence
- disinhibition
- both (delayed emergence & disinhibition)
-
Considerations:
- reduced IV anesthetic drugs (lower midaz/opioids)
- to ensure whether its cognitive irritation or too much sedative
- reduced IV anesthetic drugs (lower midaz/opioids)
-
Consequence of frontal lobe retraction →
10
Q
Anesthesia considerations for craniotomy for supratentorial, intracrnail tumors?
A
-
Control ICP (*top priority*)
- Institute measures before open dura → then visually assess
- Diuretics
- Mannitol: 0.25-1.5 g/kg
- 3% NS: 50-100 ml/hr
- hourly Na+ checks → don’t change levels too fast
- Corticosteroids
- Dexamethasone: 10 mg q6hrs (48 hrs before and during case)
- Hyperventilation
- Goal: PaCO2 ~ 25- 30 mmHg
- AVOID: PaCO2 < 25 mmHg → too much vasoconstriction (ischemic brain)
- Aline → obtain CO2 gradient (assume 5 mmHg gradient in ABG and ETCO2)
- Optimize hemodynamics
- CPP adequate
- Normovolemia
- Avoid hyposmolar fluids
- Ex:
- Plasma = 295
- LR = 273 mOsm/L (hyposmolar)
- AVOID
- *NS= 308 (hyperosmolar)
- Hyperchloremic metabolic acidosis
- *Plasmalyte/Normosol = 294 (isosmolar) <<< ideal choice
- Ex:
- Avoid hyposmolar fluids
- Normal blood glucose
- Hyperglycemic → promotes anerobic metabolism → increase brain damage
- Improve venous return (positioning)
- HOB elevated 10-15 deg (adequate venous drainage)
- Avoid PEEP
- TPL, propofol
- Parallel dec in CMRO2 & CBF
- Mild hypothermia
- Keep paralyzed → Prevent shivering
- Rewarm slowly
- Prevent coughing and bucking → could herniate through craniotomy
- deep anesthesia
- muscle relaxants
11
Q
Preoperative preparation for supratentorial intracranial tumors
A
- Pre-op LOC and CT scan evaluation
- Medication regimen (hx of seizures, decadron 24-48 hrs?, mannitol or hypertonic saline)
- Possible Lymphoma diagnosis → consider holding dexamethasone
- Result in tumor lysis and complicate diagnosis.
- Possible Lymphoma diagnosis → consider holding dexamethasone
- Pre-medication w/caution if ICP ↑
- Hypoventilation → ↑ PaCO2 → ↑ CBF → ↑ ICP
- Routine monitors & arterial line (often pre-induction)
- 2 large bore PIVs
- Consider right atrial line to measure CVP if major blood loss or VAE concerns
12
Q
Induction considerations for supratentorial intracranial tumor?
A
- Place A line pre/post
- Transducer at external auditory meatus (pressure perfusing CoW)
- Optimize ICP
- Caution w/ sedatives (hypoventilation)
- Deep induction (avoid ICP change)
- Lidocaine 1.5 mg/kg
- Fentanyl 3-5 mcg/kg
- Liberal → most pain @ case beginning (incision, bone flap, dura)
- No pain receptors on brain → little surgical pain
- Liberal → most pain @ case beginning (incision, bone flap, dura)
- Propofol 2 mg/kg
- Small bolus right before intubation too (0.5 mg/kg)
13
Q
Maintenance of supratentorial intracranial tumors
A
- VA < 0.5 MAC
- 1 MAC: Vasodilates → ↑ CBV (ok if brain looks ok)
- Propofol drip 150 mcg/kg/min
- Propofol 0.5-1 mg/kg
- Pin placement → pain
- Opioids
- Esmolol
- Pin placement → pain
- ABG – early
- See CO2 gradient
- Mannitol 1 g/kg
- Dura open
14
Q
Emergence supratentorial intracranial tumor
A
- smooth
- NO REVERSAL until pins out/head dressing on
- Avoid → ↑ risk hemorrhage/edema
- Shivering
- Pain
- Bucking
- HTN
- LTA
- Precedex
- Caution w/ HoTN
- Overall:
- Drugs easily titratable/adjust!
15
Q
What is an infratentorial/posteiror fossa intracranial tumor? Symptoms?
A
- BELOW tentorium
- Small space
- Structures of posterior fossa include: → when interrupted cause MAJOR problems
- Medulla
- Pons
- Cerebellum
- Major motor/sensory pathways
- Primary resp/CV centers
- Lower cranial nerve nuclei
- Ex: Significant CV responses***
- HTN
- HoTN
- Bradycardia
- Tachycardia
- Ex: Significant CV responses***
- Other symptoms:
- Preop dysphagia
- laryngeal dysfunction
- respiratory abnormalities
- chronic aspiration
- More common in children (ex: medulloblastoma, pilocytic astrocytoma, ependymoma, brainstem glioma)
- In Adults: acoustic neuromas, metastases, meningiomas, and hemangioblastomas
16
Q
Posterior fossa tumor monitoring?
A
- Good communication w/ surgeon!! → very small surgical space
-
Warning signs of damage to adjacent cranial nerve nuclei & respiratory centers:
- Bradycardia & hypotension
- Tachycardia & hypertension
- Bradycardia & hypertension
-
Ventricular dysrhythmias
- Communicate!! Represent damage to pons/lower medulla
- don’t treat dysrhythmias but talk with surgeon!
- Communicate!! Represent damage to pons/lower medulla
- Dissection on floor of 4th ventricle
- Possibility of injury to cranial nerve nuclei & swelling
- Even small swelling has large consequence since sx area small
- CN dysfunction IX, X, XII
- Even small swelling has large consequence since sx area small
-
Consequences: → extubate? Go to ICU for monitoring
- upper airway patency loss
- cranial nerve function loss
- respiratory drive loss
- Possibility of injury to cranial nerve nuclei & swelling
17
Q
Positioning and monitoring for infratentorial tumor?
A
- Positioning:
- Sitting, lateral, prone, park bench, or three quarters prone position (keep in mind CV effects and complications
- Quadriplegia
- Macroglossia
- Pneumocephalus
- VAE (incidence 39% in sitting position)
- PAE
- Sitting, lateral, prone, park bench, or three quarters prone position (keep in mind CV effects and complications
- ECG- alterations rate, rhythm
- Arterial line (CPP and brain stem alterations)
- BAEP/SSEP may be monitored
- TIVA (propofol) → wont interrupt monitors
- MEP or Electromyographic monitoring of facial nerve
- Need at least ~2/4 twitches on TOF at least
18
Q
Induction considerations for infratentorial tumor?
A
- Tumor detection → compression of vital areas
- Baseline AW patency issues
- CV
- Dysphagia
- Chronic aspiration
- *RSI
- *Resolve pulmonary infection 1st
19
Q
Maintenance/emergence consideratiosn for infratentorial/posterior fossa tumor?
A
- Maintenance:
- Positioning
- Sitting/HOB elevated →
- central line/CVP cath
- Doppler
- ETCO2 detection
- Sitting/HOB elevated →
- Monitor Aline → surgical interventions affecting rhythm
- Positioning
- Emergence: → ICU for >24 hrs
- Issues:
- Edema
- Hemorrhage
- Obstruction hydrocephalus
- CV/Resp changes
- LOC changes (any signs need to come back for decompression)
- Extubation:
- Awake/alert
- Ready to reintubate if needed
- Issues:
- Choose anesthetics with cardiovascular performance in mid.
20
Q
Anatomy/physiology review of pituitary gland?
A
- Pituitary gland
- lies in sella turcica (bony cavity in sphenoid bone) at skull base of skull
- very close to optic chiasm, carotids, cavernous sinus (CN III, IV, VI) → very close to structures (hemorrhage possible!)
- lies in sella turcica (bony cavity in sphenoid bone) at skull base of skull
-
Anatomy: 2 Lobes
-
Anterior (adenohypophysis) lobe
- Regulation: hypothalamus via complex portal vascular system
- GH
- PL
- PSH
- LH
- ACTH (adenocorticotropin)
- B-liptropin
- Thyrotropin (TSH)
- Regulation: hypothalamus via complex portal vascular system
-
Posterior (neurohypophysis) lobe
- Regulation: Infundibular stalk - connects posterior lobe to hypothalamus
- ADH
- Oxytocin
- Regulation: Infundibular stalk - connects posterior lobe to hypothalamus
-
Anterior (adenohypophysis) lobe
- Hypothalamus regulates anterior lobe via through regulatory peptides, (hypothalamic releasing and inhibiting factors) that reach the anterior pituitary via complex portal vascular system. Hypothalamic secretion is complex and occurs from neuronal and chemical influences, including feedback from target organ hormones. The posterior pituitary = 2 hormones ADH and oxytocin which are synthesized in specialized hypothalamic neurons and transported as granules in axons down the pituitary stalk to the posterior pituitary gland. Anterior hormones are GH, PL, FSH, LH, ACTH (adrenocorticotropin), B-liptropin, thyrotropin (TSH)
21
Q
What are functioning vs non-functioning tumors?
A
-
1. NONFUNCTIONING
-
diagnosed when large and causing symptoms by impinging on adjacent structures (ICP issues)
- ex: chromophobe adenomas, craniopharyngiomas, meningiomas
- s/s: ICP, HA, visual changes, cranial nerve palsies
- ex: chromophobe adenomas, craniopharyngiomas, meningiomas
-
diagnosed when large and causing symptoms by impinging on adjacent structures (ICP issues)
-
2. FUNCTIONING
-
diagnosed when small symptoms related to production of an excess of 1 or more anterior pituitary hormones
- ex: prolactinomas followed by GH and ACTH – secreting adenomas
- s/s:
- Prolactinomas: amenorrhea, impotence
- GH:
- Before puberty → gigantism
- After puberty → acromegaly
- ACTH: cushings dx (excessive cortisol) from bilateral adrenal hyperplasia
- s/s:
- ex: prolactinomas followed by GH and ACTH – secreting adenomas
-
diagnosed when small symptoms related to production of an excess of 1 or more anterior pituitary hormones
22
Q
Preop assessment of pituitary tumors
A
-
Panhypopituitarism?
- Tumor compressing gland → not secreting enough hormone
- Tx: Correct hypocortisolism & hyponatremia; hypothyroid, etc.
- Can rupture and be emergency
- Tumor compressing gland → not secreting enough hormone
-
Acromegaly?
- Evaluate airway, cardiac function (arrhythmias and hypertrophic cardiomyopathy)
-
AW enlargement: Enlarged tongue, narrow glottis, hypertrophied nasal turbs, mandible enlargement, glottic stenosis
- Tx: fiberoptic intubation → diff AW d/t growth
- ½ size smaller ETT d/t glottic stenosis
- Tx: fiberoptic intubation → diff AW d/t growth
-
CV enlargement:
- Hypertrophic cardiomyopathy
- Arrythmias
-
AW enlargement: Enlarged tongue, narrow glottis, hypertrophied nasal turbs, mandible enlargement, glottic stenosis
- Evaluate airway, cardiac function (arrhythmias and hypertrophic cardiomyopathy)
-
Cushing’s Disease?
- Evaluate- CV workup
- DM
- OSA
- hyperaldosteronism (hypokalemia and metabolic alkalosis)
- HTN
- CHF
- obesity
- Evaluate- CV workup
- Know size and location of tumor
- Ex: functioning/nonfx
- Pituitary microadenomas = no mass effect (fxing type → no ICP issue)
- Pituitary tumors w/suprasellar involvement- nonfxing
- Larger → evaluate for ↑ ICP
- Ex: functioning/nonfx
- Clear dexamethasone with surgeon –
- false positive for post-surgical hypopituitary function
- Visual exam
- assess optic nerve integrity
- Transsphenoidal
- nasal culture → ABX
- SIADH with sellar tumors (low sodium with fluid overload) → preop correction
- Tx: Demeclocycline (tetracycline)
- inhibits ADH activity at renal tubules (see on med list)
- Tx: Demeclocycline (tetracycline)
23
Q
Anesthetic considerations for pituitary tumor?
A
-
Monitors –
- standard +/- arterial line (working around carotids/venous sinuses)
-
Position
- Supine
- VAE precautions (doppler + right atrial line) if >15 degree surgical site-heart gradient
-
Pharyngeal pack
- Placed by surgeon → document pack removed after sx
-
ETT
- RAE
- secured lower jaw
- opposite site surgeon dominant hand
-
Transcranial Approach:
- > ICP mgt VS transsphenoidal
- Brain retraction → brain irritation risk (sz, DI, blood loss)
-
Transsphenoidal Approach: incision under upper lip, through nasal septum
- Better M&M
- High risk:
- CSF leak
- Meningitis
-
LA: 4 % cocaine & 2 % lido w/epi infiltrated èwatch dysrhythmias
- Cocaine: inhibits NE reuptake → vasoconstriction/analgesia
-
CO2 management – depends on surgical goals
- Ex: Hypocapnia → minimize brain volume → minimize arachnoid bulge degree into sella
- Ex: Hypercapnia: larger tumor w/ suprasellar extension = normal/increased CO2 → deliver lesion into sella for excision
-
VEP monitoring – MOST sensitive to VA
- Optic nerve and chiasm
-
C-Arm Fluoroscopy
- head & hands inaccessible after drape
- Peripheral Nerve Stim on LE
- IVs and Aline working well after tucking
- Check compression of C Arm on body (nerve damage)
- head & hands inaccessible after drape
24
Q
What are some considerationg for emergence following pituitary surgery?
A
- Smooth emergence - especially if CSF space has been opened
- Issues → Meningitis r/t CSF leak!!
- Valsalva maneuvers (coughing/vomiting) may contribute to reopening of a CSF leak and worsen the risk for subsequent meningitis
- Issues → Meningitis r/t CSF leak!!
- Suction well
- AW cleared of debris, including formed clots
- Packs removed
- Visual acuity should be assessed pre-extubation
- Nose packed – remind patient to breath through mouth
- fully awake extubation
- LTA
- Propofol bolus
notes:
- Smooth emergence, especially if the CSF space has been opened (and resealed with fibrin glue or by packing the sphenoid sinus with fat or muscle). Valsalva maneuvers, as with coughing or vomiting, may contribute to reopening of a CSF leak and worsen the risk for subsequent meningitis. Inspect the pharynx with a laryngoscope. The airway should be cleared of debris, including formed clots. allows one to more confidently extubate promptly at the first signs of reactivity to the endotracheal tube.
- The chosen anesthetic technique should permit gross visual acuity exam before pt. extubated. If visual acuity is worse then may need emergent decompressive surgery.
25
Q
What are some complications of pituitary surgery?
A
- CSF Leak/Rhinorrhea – meningitis (transsphenoidal*)
-
Damage to Surrounding Structures-
- CN 3-6
- cavernous sinus
- internal carotid
- hypothalamus
- optic nerve
- Optic chiasm
- Pituitary/Adrenal Axis Malfunction – dexamethasone followed by prednisone for 5 days post-op or until testing clears pt.
Pituitary Surgery: Complications- Diabetes Insipidus
- Development: 12-48 hrs postop
- rarely arises intraoperatively
- Diagnosis:
- Polyuria: 2-15 L/day
- rising serum osmolality: > 300mOs/kg
- specific gravity: < 1.005
- Treatment:
- 1/2NSD5W = Hourly maintenance fluids plus 2/3 previous hour’s urine output.
- (or hourly urine output minus 50 mL plus maintenance)
- Hourly requirement > 350-400 mL → add desmopressin (synthetic ADH)
- DDAVP: 0.5-1.0 uG IV/SQ
- 1/2NSD5W = Hourly maintenance fluids plus 2/3 previous hour’s urine output.
- One of the important surgical considerations is the avoidance, when possible, of opening the arachnoid membrane. Postoperative CSF leaks can be persistent and are associated with a considerable risk of meningitis. In situations in which one is concerned that a persistent CSF leak may occur, some surgeons will place a lumbar CSF drain to maintain CSF decompression in the early postoperative period.
26
Q
Interentions with intracranial aneurysms/SAH?
Risks? Grading?
A
- Discovered pre-rupture:
- *elective endovascular coiling (favored approach)
- surgical clipping used
- Subarachnoid hemorrhage
- CoW aneurysm rupture:
- 1/3 functional survivors
- 1/3 die before hospital
- 1/3 vegetative state
- Operative clipping versus the endovascular approach in IR
- CoW aneurysm rupture:
- Risks: 50’s (peak risk), female, HTN
- Aneurysmal SAH surgical risk and outcome predicted via grading systems
- World Fed. of Neurosurgeons – 1-5 based on GCS and Motor Deficit
- 1-2: less severe (more favorable in outcome)
- 4-5: severe
- Hunt and Hess (clinical symptoms)
- Fisher Grade (radiologic bleeding)
- World Fed. of Neurosurgeons – 1-5 based on GCS and Motor Deficit
27
Q
Symptoms of intracranial aneurysm/sah? Diagnostic?
A
- Symptoms:
- N/V
- severe HA
- stiff neck
- photophobia
- LOC
- Blood + subarachnoid space = abrupt increase ICP
- Pressure increasing → SNS response → increase catecholamines
- HTN
- dysrhythmias
- Dx: CT scan, angiography = size and location
- Small < 10 mm
- > 6 mm require treatment
- Large 10-24 mm
- Giant > 24 mm
- Small < 10 mm
28
Q
ECG changes associated with SAH?
A
Canyon T waves
- Hemorrhage → body recognizes threat → catecholamine surge
- NE/Epi → Heart exposed → dysrhythmias
- Canyon T Waves – dips in T waves
- NE/Epi → Heart exposed → dysrhythmias
- Other common changes
- ST depression or elevation
- T wave flattening
- U waves
- Prolonged QT
- Dysrhythmia
- w/in 10 days resolves
- Increase CV enzymes
36
Q
What is important to remember about autoregulation around ischemic penumbra?
A
(i.e. be careful with controlled hypotension!)
-
Ischemic penumbra – no autoregulation
- Pressure passive
- Ex: MAP 50 → low CBF
- Want high/normal MAP to get CBF close to 50 (requires much higher MAP)
- Pressure passive
Normal and absent autoregulation curves. The “absent” curve indicates a pressure-passive condition in which cerebral blood flow (CBF) varies in proportion to cerebral perfusion pressure. This curve is drawn to indicate subnormal CBF values during normotension as have been shown to occur immediately after both head injury and subarachnoid hemorrhage. The potential for modest hypotension to cause ischemia is apparent.
44
Q
What is the patho behind head injuries? review of gcs?
A
- Patho: 2 Injuries
-
Primary injury – we have no control
- biomechanical effect of force applied to skull and brain (milliseconds)
-
Secondary injury (goal = prevention)
- Excitotoxicity- glutamate
- Ischemic penumbra- optimize chance of neurons here survive
- Patho: Ischemia, brain swelling, edema, intracranial hemorrhage, increased ICP, herniation (minutes to hours)
-
Aggravating factors: → secondary injury worse
- Hypoxia
- Hypercarbia
-
Hypotension**- max CPP
- hypoxia + hypotension significantly worse > 90% patients severe outcome or death
- Anemia
- Hyperglycemia
- Seizures
- Infection
- 40% will have another life-threatening injury
Glasgow Coma Scale – defines neurologic function impairment
- Eyes open – Never (1)-spontaneous (4)
- Best Verbal Response None (1) – oriented (5)
- Best Motor Response None (1) - obeys commands (6)
- Mortality closely related to initial score
- Scores < 8 = considered severe
- require intubation and controlled ventilation for ICP & airway control
46
Q
What is involved with inline stabilization during intubation?
A
- 3 person job
- # 1- hold manual c-spine stabilization against bed (no flexion)
- No sniffing position
- # 2- laryngoscopist
- # 3- cricoid pressure to prevent aspiration
- # 1- hold manual c-spine stabilization against bed (no flexion)
65
Q
Sterotactic procedures
A
- Derived from Greek word stereos, meaning three dimensional, and the Latin word tactus, meaning to touch
- MRI/CT allows precise three-dimensional localization of specific sites within the CNS increasing the neurosurgeon’s accuracy
Overall → AW issue (cant bag/mask vent if needed)
- NEED to have someone w/ you who can remove frame if necessary
- Anesthesia:
- Sedation/Awake
- Scalp block
-
Use of Stereotactic Procedures:
- biopsy of small deep-seated lesions
- placement of deep brain stimulation electrodes
- ex: Parkinson’s disease /movement disorders/Tourette’s/Depression
- ablation of lesions close to critical speech, motor, short term memory centers (movement disorders & temporal lobe epilepsy)
- Anesthesia:
Needle placement picture
- ensure pt off meds that promote bleeding
- herbals
- anticoags
- the future - intraparenchymal stimulators for control of epilepsy and stereotactic stem cell implantation for a variety of degenerative and ischemic disorders??
66
Q
Preop eval for sterotactic procedures?
Process of placing frame?
A
-
Preoperative evaluation:
- coagulation status (platelet-inhibiting agents & herbals)
- patient education – plan w/procedure duration & movement restraints
- Planned awake → immediate feedback (bleeding/procedure working)
- Stereotactic frame placed
- local anesthetic (scalp block)
- picture
- (+/- sedation)
- Ex: Propofol 100-150 mcg/kg/min → scalp block while sleepy → frame placed
- local anesthetic (scalp block)
- The patient then undergoes imaging study prior to OR
- Bag-mask ventilation may be impossible (frame) - anesthetist must know how to remove
- Frame will prevent application of the mask and ventilation, laryngoscopy, or neck extension. If a general anesthetic is to be administered, awake intubation may be required. If sedation is to be used should have certain knowledge regarding how to remove the device rapidly in an urgent situation (including knowledge of the whereabouts of the requisite “key” or spanner device).
