post op visual loss

0.01-1%

commonest causes

- ischaemic optic neuropathy (posterior more common; opthalmic artery branches, risk: hemorrhagic hypotension, not necc with extrinsic compression)

-central retinal arterial occlusion (retinal artery thrombosis: retinal pallor, cherry red spot)

(extrinsic compression)

commonest risk factors:

patient - closed angle glaucoma; male patient, diabetic, hypertension, atherosclerosis, smoking

surgery: prolonged, massive blood loss, anemia

anaesthesia: hypotension, extrinsic pressure on eye, increased CVP (resulting in increased IOP), prone position itself increase IOP (head dependent- worse; head up, better)

ameliorating: position 10' head up, careful no pressure on eye, higher transfusion trigger

PDPH

PDPH

http://www.acep.org/content.aspx?id=32526

frontal headache that can become generalised, can radiate to interscapular region
visual changes, cranial nerve palsy, tinnitus, photophobia
worsened by movements that increase ICP (coughing,sneezing)
worse on sitting up
Gutshe sign: firm manual p on abdomen: temporary relieve

increased risk:
female, pregnancy, pre existing headache,

small gauge, higher number- a/w less headache and hearing loss
size of needle, placement of tip, orientation of bevel (longitudinal orientation- lower risk)

cutting : quincke
pencil: whitacre, sprotte, -lower incidence of PDPH
pencil point: more trauma, more inflammation, promote healing?
- but need operator expertise

cutting 36% (22G Quincke), 3-25% (25G Quincke), whitacre 3%- randomised trial
16G tuohy 70%

operator experience and amt of fluid used-not significant\
lying supine/bedrest-not shown to be effective


MANAGEMENT:

DIFFERENTIALS:
cerebral venous sinus thrombosis,
migraine,
caffeine withdrawal

epidural abscess

(Sep-2004 Q4) Outline the diagnostic criteria for an epidural abscess

high index of suspicion, may also occur spontaneously without spine/epidural instrumentation

minor

fever- after excluding other causes

procedure: difficult epidural, multiple attempts, no aspetic technique

patient factors: systemic sepsis, DM, immunocompromised

major:

localised back cellulitis

neurological signs- cauda equina, LL weakness, loss of sensation, persistent back pain

MRI findings

radial art cannulation

(May-2008 Q2) Why is the radial artery a common site for arterial cannulation? What complications may occur from radial artery cannulation and how may they be minimised?

The radial artery is a common site for cannulation because it is superficial and easy to assess, distal and therefore allows more proximal arteries to be left intact in case of failing to cannulate distally, the proximal brachial artery is still available as an alternative (although this is not ideal).

It is compressible and therefore in the case of a hematoma, expansion of the hematoma may be limited by direct pressure

Clean, correlates well with BP, collateral circulation, discrete from nerves

Complications:

1) hematoma

2) thrombosis/ vasospasm/air bubbles leading to distal ischaemia

- minimized if pre cannulation allen’s test is done to ensure presence of collateral circulation to the hands prior to radial art cannulation

3) infection- this may be minimized by using an aseptic technique, vigilance for infection/ cellulitis and prompt removal of the cannula, changing the site of the cannula every week (?evidence?) strict asepsis when obtaining blood samples from cannula

4) Invasive arterial cannulation only when indicated : >4 ABG /day, hemodynamic monitoring crucial

5) Drug injection- adequate labelling, staff training, prompt recognition if drug has been given to do corrective measures

aspiration

(May-2006 Q1) List the predisposing factors for aspiration of gastric contents in a patient undergoing general anaesthesia. Discuss the measures you would take to prevent this complication.

Predisposing factors :

1) patient factors

- GERD

- Pregnancy

- inadequate fasting : 8 hours or more for fatty food, 6 hours for milk or solids, 2 hours clear feeds, 3-4 hours for breast milk in <4 month old infants

- type of food

- medications that slow gastric emptying: opioids

- distracting injuries: trauma

- GI stasis: I/O

2) surgical factors

- laparoscopic surgery

3) anaesthesia factors

- use of a supraglottic device

- gastric insufflation with BV ventilation

- no RSI

altered consciousness/ severe TBI (GCS),

loss of laryngeal reflexes eg stroke/ Parkinson’s

difficult airway

pre op

prevent aspiration

-await gastric emptying if possible

reducing morbidity from aspiration: with reducing volume and acidity : adequate fasting , prokinetics, PPI or antacids/ H2 antagonists

inducing with head up position/shoulder roll/ avoid BVM , intubate with RSI, inflate cuff appropriately

ryles tube to reduce gastric contents

extubate awake