Your Daily Meds - 16 December, 2022

Luke Reynolds

Dec 16, 2022

Good evening and welcome to your late Friday dose of Your Daily Meds.

Bonus Review: Are there tissues where pressure autoregulation does not occur?

Answer: Yep -

Uterine circulation during pregnancy - is pressure dependent, and blood flow can decrease to half its normal value before foetal oxygenation is affected
Hepatic portal circulation - because it is simply venous drainage of the bowel

Why don’t we look at a Procedure:

As if to an examiner, consider and describe the steps for peripheral intravenous cannulation.

Hint: you can never wash your hands too much.

Pause. Write down an excessive number of dot points if you like, and meet me further down.

Case:

Young adult. Serious car crash. Wakes from unconsciousness and complains of double vision. On examination - double vision only occurs when looking to the right. Vision front and left seems normal. Which of the following cranial nerves is most likely damaged in this case?

Left third nerve
Right sixth nerve
Left fourth nerve
Right fourth nerve
Left sixth nerve

Pause. Have a think and meet me at the bottom.

The PIVC Dance:

I did say excessive dot points…

Introduction
- Wash hands
- Introduce yourself
- Confirm patient – name / DOB
- Check for allergies
- Explain procedure
- Check understanding and gain consent
Get equipment
- Put everything on a trolley.
  1. Clean tray
  2. Non-sterile gloves
  3. Tourniquet
  4. Cannula – appropriate size - resuscitation V antibiotics
  5. Sterile dressing pack
  6. Cannula dressing
  7. Luer lock bung cap or extension set
  8. Gauze swabs
  9. Normal saline (0.9%) – 10ml
  10. Syringe – 10ml
  11. Alcohol swab(2% chlorhexidine gluconate in 70% isopropyl)
  12. Sharps container
Prepare
- Don gloves (prior to drawing up your saline flush)
- Open the dressing pack and place the cannula, cannula dressing and other items onto the field
- Prepare the normal saline flush
- Place a pillow under the arm to be cannulated if able
Identification of a suitable vein
- Position the patient’s arm in a comfortable extended position
- Inspect the arm for suitable vein
- (Ask the patient if they have a preference as to which arm should be cannulated)
- Apply the tourniquet – approximately 4-5 finger widths above the planned puncture site
- Palpate the vein
  1. Ideally straight
  2. Tapping a vein and asking the patient to repeatedly clench their fist can make the vein easier to visualise and feel
- Things to avoid when cannulating:
  1. Arterio-venous fistula, lymphoedema, previous mastectomy
  2. Avoid areas of broken, bruised or infected skin(cellulitis)
- Clean the site with an alcohol swab for 30 seconds and then allow to dry completely over 30 seconds
Inserting the cannula
- Wash hands again
- Don non-sterile gloves
- Remove cannula sheath
- Prepare cannula
- Secure vein with your non-dominant hand from below
- Warn the patient of sharp scratch
- Insert the cannula directly above the vein, through the skin ( at an angle of 10-30º with the bevel facing upwards)
- Observe flashback in the cannula chamber
- Decrease angle between the needle and skin, then advance the needle a further 2mm after flashback to ensure within vein’s lumen
- Carefully advance the cannula into the vein fully
- Release the tourniquet
- Apply pressure to the proximal vein close to the tip of the cannula to reduce bleeding
- Gently pull the introducer needle backwards whilst holding the cannula in position until it is completely removed
- Connect a luer lock cap or primed extension set to the cannula hub
- Dispose of the introducer needle immediately into a sharps container
Flushing the cannula
- Inject the saline into the cannula using saline flush through bung
- Secure the cannula with a dressing if the cannula is functioning appropriately
To complete the procedure
- Dispose of the clinical waste into an appropriate bin
- Wash hands
- Thank patient
- Document date, time and initial on adhesive sticker on dressing

Then exhale…

On Double Vision:

Recall the innervation and action of the extraocular muscles.

In this case, the right sixth nerve is most likely damaged as diplopia is only occurring when the patient looks right, the time that the right lateral rectus muscle would be needed. So, damage to the sixth cranial nerve causes diplopia on lateral gaze to the affected side.

The fourth cranial nerve supplies the superior oblique muscle. Damage to the fourth nerve is more likely to cause diplopia when looking down.

I think there is a mnemonic thing of: SO4, LR6

Third nerve palsies paralyse all extraocular muscles except for the lateral rectus and superior oblique muscles, along with the parasympathetic supply to the pupillary muscles. Third nerve palsies present with the eye angled ‘down and out’. Note that this ‘down and out’ position is due to the unopposed action of the lateral rectus and superior oblique muscles, under control of the sixth and fourth cranial nerves respectively.

FOAMED Friday:

Thanks so much for reading along.

It’s time for a break so we will see you again in the New Year.

Or you might consider sharing this post with someone else who might find Your Daily Meds useful.

Remember, you are free to rip these questions and answers and use them for your own flashcards, study and question banks.

As always, please contact me with any questions, concerns, tips or suggestions. Have a great day!

Luke.