Outline of
Neurosurgery
E. R. Flotte, 2008
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and corrections to admin@flotte2.com
Awake Craniotomy & Cortical
Mapping
Neuroregeneration and Stem Cells
Critical
Care/Neuromedicine
Anesthesia
·
Sedatives:
Versed, Thiopental
·
Narcotics
·
Nitrous
oxide: Avoid with pneumocephalus. Stop before dural closure to prevent tension pneumocephalus.
·
Ketamine increases CBF
·
Sodium
thiopental most rapidly lowers ICP (faster than other agents or
hyperventilation)
·
Dexmedetomidine (Precedex): α2-agonist, anxiolytic, analgesia, “cooperative sedation”. Used in
awake craniotomy, NICU. (ON7/05)
·
Paralytics
o
Succinylcholine: 1mg/kg – 3.5 to 5cc, lasts 5-10min. do not use with spinal cord
injury, hyperkalemia
o
Pavulon reversal: Neostigmine (2.5-5mg
IV) + atropine (0.5mg/mg neostigmine) or Robinul (0.2mg/mg neo). Takes 20 min
·
Malignant hyperthermia: Dantrolene (2.5mg/kg, up to 10mg/kg), 100% O2, D/C
anesthesia & change tubing. Occurs w/ inhalational + Sux.
↑ ETCO2. 50% previous normal
anesthesia. Can test preoperatively with muscle
biopsy.
·
ASA
Class estimates patient physical status
·
Occurs when venous pressure is lower than atmospheric
pressure and the venous system is open to the atmosphere. Most likely to occur
in the sitting position
·
Detection: precordial doppler (most sensitive), ¯ EtCO2
(earliest), FEN2, ¯ CO, PAP, pulmonary
vascular resistance, ventilation-perfusion mismatch.
·
Treatment: Lower the head-of-bed, cover wound with
wet laps, aspirate air through central line, 100% O2.
Ventilation
·
Intubation/Extubation: 100mg lidocaine IVP, 100% O2 x 5min.
·
Tube:
20-22cm at gum line, tip 5cm above carina
·
PCWP
<12, PA 15-30/4-12, CI 2.8-4.2
Arrythmias
·
Afib/Aflutter: Verapamil (5mgx2), Diltiazem (0.25mg/kg 10-20mg). (adenosine, procainimide; digoxin for
flutter) If unstable cardiovert 100J.
·
Other SVT: Vagal maneuver, Adenosine (6mg-12mg-12mg), verapamil, diltiazem
·
Vtach, Vfib: Pulseless:
Epi (1-3-5mg); Other: Lidocaine (1mg/kg q5m x 3), procainamide (20-30mg/min to 12mg/kg), bretylium
(10mg/kg q5m x 3)
·
Asystole: Epi, atropine (0.5mg x 4)
·
Bradycardia: atropine
Myocardial infarction
·
Clopidogrel with aspirin is recommended for unstable
angina or minor myocardial infarction; ticlopidine is
not recommended
Antihypertensives
·
Nipride: onset seconds, Follow thiocyanate
levels if used >24hrs. 0.3-10mg/kg/min. Avoid in pregnancy
·
Nitroglycerin:
10-20 mg/min, 0.4mg SL q5m x 3
·
Both
raise ICP.
·
Hydralazine: onset 3-5min, duration 2-4hrs. OK in pregnancy. SE:
tachycardia. IM 10mg, IV 20-40mg prn.
·
Labetalol: onset 5m, duration 3-3hrs; 20-40-60-80mg IV, 200mg po bid
·
Esmolol.
·
Vasotec: 1.25-5mg q6hrs prn
Shock
·
Dopamine:
2-20 mg/kg/min, b>ab.
·
Dobutamine: 2.5-10mg/kg/min, b only (inotrope, BP unchanged). Use for cardiac failure if normotensive.
·
Palpable
pulses: radial 80, femoral 70, carotid 60
Steroids
·
Cause
pancreatitis
·
Addisonian crisis: hydrocortisone (Solucortef)
100mg IVP then 50mg q6h (not Solumedrol)
Anaphylaxis
·
Treatment:
Epinephrine 1:1000 5ml SQ, Benadryl 50mg IM, Decadron
10mg IV
·
Urticaria: Benadryl 50mg PO/IM + Cimetadine 300mg PO/IV
·
Vasovagal reaction: hypotension, bradycardia. Tx: Atropine 0.75mg IV, q 15min to 3mg
DVT
·
Incidence in neurosurgical patients: 15-20%
·
May be increased in craniotomies due to release of
brain thromboplastin
·
Calf
vein thrombosis has <1% risk of PE, however they may progress to DVT
·
Prophylaxis: Heparin
5000 U SQ BID, Lovenox 30mg SQ BID. TEDs/SCDs (do not use if DVT is present)
o
ACCP
guidelines: fondaparinux is a alternative to
low-molecular-weight heparin (LMWH), because it is equally safe and effective
but has a longer half-life, a more predictable response, and fewer adverse
effects
o
Moderate-risk
surgical patients: Heparin 5000mg SQ BID or LMWH (less than 3,400 U once daily)
o
High-risk
surgery patients: Heparin 5,000 U SQ TID or LMWH more than 3,400 U daily
o
Aspirin
is not recommended
·
Diagnosis:
o
Doppler
ultrasound: Standard
o
Clinical
diagnosis (calf tenderness, warmth) is unreliable.
o
The fibrinogen uptake test and impedance plethysmography
have low accuracy and are not recommended
o
Contrast venography has high sensitivity
but limited availability and questionable use for small distal thrombi and high
patient discomfort. Use is limited to research
·
Treatment: Bedrest
x 10days, then careful ambulation. 3-6 months full anticoagulation then
low-dose coumadin (INR 1.5-2).
o
Three randomized trials of anticoagulants vs
no anticoagulants in DVT showed no benefit with heparin and vitamin K
antagonists (combined all-cause mortality: anticoagulants = 6/66, un-anticoagulated controls = 1/60, P = .07). No
placebo-controlled trials of low-molecular-weight heparins or thrombolytic drugs have been done; therefore, their
efficacy in VTE depends entirely on randomized comparisons with unfractionated heparin. They have not been proven safer or
more efficacious than unfractionated heparin. Thrombolysis causes more major and fatal bleeds than
heparin and is no more effective in preventing PE (CundiffDK
9/04).
Pulmonary Embolism
·
Diagnosis:
o
V/Q scan:
§
Normal
scan rules out PE.
§
High
probability (88% true positive) then treat.
§
Low
or moderate probability then obtain leg dopplers
and if positive then angiogram to confirm.
o
o
Angiogram
·
Treatment:
anticoagulation or IVC (
Fat
embolism
·
Occurs 12-48hrs post-injury
·
Symptoms: dyspnea, petechiae over thorax, tachycardia, tachypnea.
·
Labs: serum lipase in 50%. Look for fat in blood, urine. No
specific test.
·
Cerebral embolism (causing confusion, somnolence, seizures) does not occur without lung symtoms
unless a PFO or ASD exists.
·
Treatment: O2, PEEP. Steroids controversial.
Anticoagulants
·
Preoperative
management
o
Mechanical
Heart Valve: stop coumadin 2d preop & admit on
heparin.
o
A-fib:
Stop coumadin 5d preop, can restart 5d postop
Antibiotics
·
Aminoglycosides/Gentamycin: Poor CSF
penetration. SE: nephrotoxic (ATN), ototoxic, vestibulitis, worsens myasthenic crises,. Coverage: Gram
(-) (no strep).
·
Sinus
entry: Gentamycin, Clindamycin
·
A
meta-analysis of eight randomized clinical trials (RCTs)
showed that prophylactic antibiotics reduce rates of postoperative infection by
approximately 75% after craniotomy (Barker FG N1994)
Electrolytes
·
AG
= Na – (Cl + HCO3)
·
Osm = 2(Na+K) + BUN/2.8 + Glu/18
·
Hyponatremia: 1.0-1.5 meq/L/hr, 25meq/L/d, 3%
Na 25-50cc/hr + Lasix
·
SIADH
o
Diagnosis:
Na<134, Osm<280, UNa
>50.
o
Treatment:
Fluid restriction <1L/d. 3% NaCl. Chronic: demeclocycline (300mg po q8°) or
lithium
o
Versus
cerebral salt wasting: ↓↓ serum Na, ↓ or wnl
BUN/CR, ↑ plasma volume, ↑ CVP/PCWP, no dehydration signs
·
Diabetes
Insipidus (DI)
o
Treatment:
1/2NS, DDAVP/desmopressin (0.1-0.2 μg IVq8°). Chronic: Intanasal
DDAVP (10-40μg BID)
·
Hyperkalemia: 10% CaGluconate 5-10cc over 2m;
1 amp HCO3; 5-10U regular insulin + 1 amp D50; Kayexalate
·
Heparin:
Reportedly no higher risk in patients with brain tumors
·
Coumadin:
always pre-heparinize
Hematology
·
Estimate of pediatric blood volume: 90-100ml/kg for premature infant,
80mg/kg for term infant, 75ml/kg for 1-12mos, 70ml/kg for >1 year
·
Platelets: 1 units
raises platelet counts by 5-10K. Do not use with autoimmune destruction (eg ITP).
·
Fresh Frozen Plasma
·
Vitamin K: 10mg IM. PT reversal requires 6-12 hrs. (Do
not give IV)
·
Prothrombin complex
concentrate reverses coumadin 5x more quickly than FFP
·
Transfusion Reactions
- Hemolytic: Due to ABO
incompatibility. Symptoms: chest pain, shock. Stop transfusion, mannitol, IV fluids.
- Allergic: Due to plasma
proteins. Causes hives. Treatment: Benadryl.
- Febrile: Treatment: Tylenol.
Send blood for analysis to rule out hemolysis
·