Lumbar Punctures Flashcards
Indications for an LP? [6]
To Diagnose:
- Meningitis/Meningoencephalitis
- Subarachnoid Haemorrhage
- Malignancy (diagnose & Treat)
- Idiopathic Intracranial Hypertension
- Detect Oligoclonal bands to indicate CNS inflammation e.g. MS
To infuse drugs or contrast
Contraindications for a LP? [4]
- Patient has cardiovascular or respiratory Instability
- Infection in skin or soft tissue over puncture site
- Unstable bleeding disorder (diagnosed, low platelets or low clotting factors)
- Raised ICP (CT first to spot a mass which may herniate), obstructive hydrocephalus
What are the types of LP needle? [2]
- Spinal needles usually 22 gauge
- Atraumatic needles (Cause less spinal headaches but cost more)
What is used to anaesthetize for an LP? [2]
Topical anaesthetic to injection site such as EMLA
OR lidocaine inserted intradermally, then carried through on needle
In what positions are an LP performed? [2]
Lateral (Decubitus) position:
- Lying on left side with maximally flexed spine (particularly at hips)
Sitting (Infants):
- Infants hands held between its flexed legs using one hand and the other hand flexes its head
What vertebral level is an LP performed? [2]
L3-4 in adults and L4-5 in infants
Procedure for an LP [8]
- ~Anaesthetize topically 30 mins before
- Adopt position
- Clean skin with Povidone Iodine to 10cm from puncture site and allow to dry
- Drape below patient and around site
- ~Anaesthetize with lidocaine
- Insert spinal needle + Stylet with bevel upwards (90 to spinal cord)
- Aim Cephalad to get through slanted lamina
- Pop of sudden lack of resistance means your in, remove stylet and collect CSF
What do you do if theres no fluid? [3]
- Rotate the needle 90 degrees
- Reinsert stylet and advance needle again
- Compress jugular
How is CSF pressure measured? [1]
With a Manometer in the lateral position only, once CSF starts to flow
How much CSF do you collect on an LP?
3 vials as standard:
- Culture & gram stain
- Glucose & Protein
- Cell count & DDx
How is the LP ended? [3]
Measure closing pressure with manometer if you want
- > Reinsert Stylet
- > Smoothly remove needle
- > Cleanse and cover puncture site
What is the Paramedian or Lateral Approach? [2]
What are the benefits of this approach? [3]
Approaching the spine at an angle not quite in the midline (10-15 degrees out) [1]
This passes through the erector spinae & Ligamentum flavum rather than Supraspinal/interspinal ligaments [1]
Helps in patient with calcifications, anatomical abnormalities or just to reduce Spinal Headaches (hole through dura &arachnoid wont overlap)
Complications of a LP? [8]
- Headache
- Apnea
- Back pain, bleeding or leaking
- Infection or Haematoma
- Subarachnoid Epidermal cyst (Carried Skin cells through to meninges)
- Nerve Trauma, Ocular Muscle Palsy
- Brainstem Herniation
Describe a spinal headache?
SOCRATES
Risk factors [3]
A common complication of LPs
More likely in women, young people, low BMIs and people with a history of headaches
Its bilateral and improves with lying down
It can last hours to weeks
How do we treat a spinal headache? [3]
We can help with:
- Hydration
- Caffeine (PO/IV)
- Epidural Blood Patch to stimulate healing
Bacterial meningitis findings on LP
* Appearance
* Glucose?
* Protein?
* White cells?
Viral meningitis findings on LP
* Appearance
* Glucose?
* Protein?
* White cells?
TB meningitis findings on LP
* Appearance
* Glucose?
* Protein?
* White cells?
