Your Daily Meds - 16 December, 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.
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…
Confirm patient – name / DOB
Check for allergies
Check understanding and gain consent
Put everything on a trolley.
Cannula – appropriate size - resuscitation V antibiotics
Sterile dressing pack
Luer lock bung cap or extension set
Normal saline (0.9%) – 10ml
Syringe – 10ml
Alcohol swab(2% chlorhexidine gluconate in 70% isopropyl)
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
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:
Arterio-venous fistula, lymphoedema, previous mastectomy
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
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
Document date, time and initial on adhesive sticker on dressing
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.
On the Spoon as a Surgical Instrument -
Thanks so much for reading along.
It’s time for a break so we will see you again in the New Year.
Thanks for reading Your Daily Meds! Subscribe for free to receive new posts and support my work.
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!