Airway part 2 and LPs Flashcards
Indications for an LP
CSF analysis to evaluate for subarachnoid hemorrhage, meningitis, encephalitis, subarachnoid bleed, intracranial pathology, CNS infection, HA workup, etc.
To drain CSF or measure CSF pressure
For spinal anesthesia to inject meds
CIs for an LP
Relative CI in its with coagulation defect or platelets <50,000
Increased ICP
-Creates pressure differential- herniates brainstem
Skin infection overlying area where LP is to be performed
Previous lumbar surgery (increases difficulty but may not be absolute CI)
Equipment needed for an LP
Spinal needle - <1 yr: 1.5 in - 1 yr to middle childhood: 2.5 in -Older children and adults: 3.5 in Three-way stopcock Manometer for pressure measuring 4 specimen tubes Local anesthesia Drapes Betadine
How to utilize aseptic technique
Skin prep
Gloves
Drape
Mask
What must be done before every procedure for an LP?
Get informed consent (will take a few minutes or you’ve done a bad job!)
Must discuss complications
Location of LP
Spinal cord ends in caudal equine around L1-L2, so do LP at L2-3 or lower
L3-4 is preferred (less likely to damage spinal cord)
What needle to use for local anesthesia before LP
25-27 gauge needle
Pt position for LP
Lumbar flexion
Make sure pt does not bend at the hips
Use helper for positioning help because you’re sterile
Can hit bone if not properly positioned
Needle size for actual LP
20-22 ga. (or smaller)
Avoid 18.19 ga
Anatomy of an LP
Going after subarachnoid space
Dura is thicker than subarachnoid
Can feel resistance of dura
Palpate the iliac crest to find lumbar level
What is the approach for an LP?
Midline approach (palpate spinous processes)
Procedure of the LP
Check for fluid-measure opening pressure; but if suspect elevated CSF pressure, should do head CT first
Collect 4 tubes of fluid (approx 1 mL each)
Withdraw needle, hold pressure
Apply dressing
Bedrest with no elevation of HOB 2-5 hrs
Hydration
What occurs when pressure is nl in an LP?
What occurs with increased pressure in an LP?
If nl, there will be a steady drip
If increased, there will be a fast stream
-Think about withdrawing needle
What are the typical studies obtained for a diagnostic LP?
Tube #1: Protein and glucose (chemistry)
Tube #2: Cell count and differential
Tube #3: Gram stain and culture
Tube #4: Hold for further studies
Optional CSF studies
Viral studies
Repeat cell counts (look for change from tube #2 to tube #4; indicates traumatic tap, i.e blood in sample)
Cytology
Immunology
Nl CSF results
Appearance- clear Pressure 50-175 mm H2O Spec gravity 1.006-1.009 Nl neg -Gram stain -Culture -Serology Glucose: 40-80 mg/dL Total protein: 15-50 mg/dL RBCs: none (unless traumatic tap) WBC: 0-5/micoL Diff: 60-80% lymph 10-30% mono
Abnl CSF results- total protein
Bacterial meningitis: 50-1500 mg/dL
Viral meningitis: nl to increased
HIV: 50-100 mg/dL
Fungal infection: 500-2000 mg/dL
Abnl CSF results- WBCs/microL
Bacterial meningitis: 1000-5000 (monocytes)
Viral meningitis: 10-1000 (lymphocytes)
HIV: 300 or more
Fungal: 50-1000 (varies, eosinophils)
Abnl CSF results- glucose
Bacterial meningitis: low (slightly to very low)
Viral meningitis: nl to slightly low
HIV: nl
Fungal: nl to slightly low
LP traumatic tap
Doesn’t mean trauma in the usual sense
Refers to nicking a blood vessel, which then releases some blood into the CSF
Dura is surrounded by network of epidural veins; small penetrating branches of vessels in subarachnoid space
Totally unrelated to poor technique, rather is just a statistical reality
Blood gradually clears from CSF so cell count 4th tube is decreased compared to 2nd tube
Potential complications of an LP
Postdural HA (usually very severe HA) Nerve damage Bleeding-epidural hematoma Infection (meningitis, abscess) Needle breakage
Postdural HA
MC complication of LP
F > M, youth > aged
Positional HA- supine better, sitting/standing worse
Related to needle size (>size = > risk) and technique
Caused by change in pressure CSF pressure or continued fluid leak; appears in several hours to few days
Can be a very severe, debilitating, front-occipital HA; nausea is common