Caudal

Indications

• Anaesthesia and analgesia below the umbilicus. Paediatric patients do not generally tolerate surgery under regional anaesthesia alone. However in the very young a caudal block may be adequate to carry out urgent procedures such as reduction of incarcerated hernias, allowing return of normal bowel function prior to surgical repair. Anaesthesia can be provided for superficial operations such as skin grafting, perineal procedures, and lower limb surgery. A general anaesthetic will often be required in addition. Pain relief will extend into the post operative period. The duration of the block can been prolonged by the addition of an opiate (pethidine 0.5 mg/kg) to the local anaesthetic. The possibility of delayed respiratory depression from epidural opiates needs taken into account, and patients should monitored in an intensive care or high dependency unit for 24 hours following their administration.

• Obstetric analgesia for the 2nd stage or instrumental deliveries. Care should be taken as the foetal head lies close to the site of injection and there is real risk of injecting local anaesthetic into the foetus.

• Chronic pain problems such as leg pain after prolapsed intervertebral disc, or post shingles pain below the umbilicus.

Contraindications

• Infection near the site of the needle insertion.
• Coagulopathy or anti coagulation.
• Pilonidal cyst
• Congenital abnormalities of the lower spine or meninges, because of the unclear or impalpable anatomy.

Anatomy

The caudal epidural space is the lowest portion of the epidural system and is entered through the sacral hiatus. The sacrum is a triangular bone that consists of the five fused sacral vertebrae (S1- S5). It articulates with the fifth lumber vertebra and the coccyx.

The sacral hiatus is a defect in the lower part of the posterior wall of the sacrum formed by the failure of the laminae of S5 and/or S4 to meet and fuse in the midline. There is a considerable variation in the anatomy of the tissues near the sacral hiatus, in particular, the bony sacrum. The sacral canal is a continuation of the lumbar spinal canal which terminates at the sacral hiatus. The volume of the sacral canal can vary greatly between adults.

The sacral canal contains:

1. The terminal part of the dural sac, ending between S1 and S3.

2. The five sacral nerves and coccygeal nerves making up the cauda equina. The sacral epidural veins generally end at S4, but may extend throughout the canal. They are at risk from catheter or needle puncture.

3. The filum terminale - the final part of the spinal cord which does not contain nerves. This exits through the sacral hiatus and is attached to the back of the coccyx.

4. Epidural fat, the character of which changes from a loose texture in children to a more fibrous close-meshed texture in adults. - predictability of caudal local anaesthetic spread in children and its unpredictability in adults.

Choice of drugs & dosage

Drugs that are commonly used include Lignocaine 1% and Bupivacaine 0.25%, although higher concentrations may be needed for muscle relaxation. Drugs used for epidural injections should come from single use ampoules and be preservative free.

Various regimes have been produced to calculate the appropriate dose of local anaesthetic, the doses vary widely:

1. Armitage recommends bupivacaine 0.5ml/kg for a lumbosacral block, 1 ml/kg for a thoraco-lumber block, and 1.25 ml/kg for a mid thoracic block. He recommended the use of 0.25% bupivacaine for the block up to a maximum of 20 ml. For larger volumes he recommended adding one part of 0.9% NaCl to three parts local anaesthetic to produce a 0.19% mixture

Scott's lower doses are more likely to produce analgesia to the expected height, whereas Armitage will get anaesthesia. Dosages for adults are 20-30 ml for a block of the lower abdomen and 15-20 ml for a block of the lower limb and perineum.

Care is needed to avoid the use of toxic doses of drugs for high blocks. The recommended maximum dose of Bupivicaine is 2 mg/kg or Lignocaine 4 mg/kg. These dosages are the maximum for a correctly injected dose. If the drug is mistakenly injected intravenously very small dosages may cause serious toxicity

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 PRO CON

peri op anticoagulation

epidural hematoma risk: 1:1700 to 1:200000

spinal cord damage and paraplegia, nerve injury

MASTER trial

Rigg, et al. Lancet 2002; 359:1276-1282

multicentre RCT in Australia 1995-2001

P:high risk patients undergoing major abdominal surgery, 915 patients

I: intraop epid and post op epid for 72 hr

C:GA

O: mortality at 30 days or major post op morbidity

of all complications: only respi failure less frequent, pain scores over first 3 days were significantly lower.- may be some benefit
low risk of serious adverse reactions

NO SIGNIFICANT DIFFERENCE OVERALL

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

Bier's block

August Bier- surgeon 1900s (prilocaine)

now: lidocaine

for surgeries <1 hr

double cuff tourniquet

IV cannula

Esmarch bandage

exsanguinate

inflate distal cuff then proximal cuff then deflate distal cuff

SBP 100mmHg above systolic p

lignocaine through IV cannula (12-15 ml of 2% vs 20ml of 0.5% )

deflate for 10seconds, reinflate 1 min then deflate again

disadvantages:

- tourniquet pain for longer ops

- no post op analgesia

Interscalene

indications:

-shoulder, lateral clavicle, ACJ, proximal humerus

-elbow (low interscalene)

-not good for hand (should use axillary/infraclav)

sitting

complications:

Horner's syndrome

Occurence of ipsilateral ptosis, hyperemia of the conjuctiva, and nasal congestion is common and it is dependent on the site of injection (less common with the low intrascalene approach) and total volume of local anesthetic injected; the patients should be instructed on the occurence of this syndrome and reassured about its benign nature

Phrenic Nerve paralysis (CONFIRMED!)

superficial cervical plexus block

what: anterior primary rami of C2-C4

block will block 4 major branches --antero lateral neck sensory innervation

landmarks: mastoid process-->midpoint (Chassaignac's tubercle of C6 transverse process)-->

branches emerge from posterior border of SCM

fan block and midpoint of the line

depth: superficial only, no more than 1-2cm

shud not have paraesthesia

sensory block only so dilute ok: 0.25% bupivacaine, 10 ml (5 up 5 down)

Lower limb block anatomy

http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/figures/2007F21.gif

ESRA anticoagulation guidelines

http://www.esra-learning.com/site/generalites/anticoagulation/b_anticoagulation.htm

unfractionated heparin

during low-dose administration of unfractionated heparins, an interval of 4 hours should be observed between heparin administration (usually 5000 IU s.c.) and epidural puncture or catheter removal, in order to avoid bleeding complications. Any repeat administration of low-dose heparin should then follow at the earliest after 1 hour.

risk of haemorrhage after epidural anaesthesia and subsequent heparinization is not increased if the heparinization is carried out at the earliest 1 hour after spinal/epidural puncture and is closely monitored. (and no concurrent antiplatelets)

LMW Heparin

The advantages-high level of bioavailability (ca. 100%) after sc administration and their long half-life of 4–7 hours. Max effect 4hrs post admin

-gold standard for thromboembolism prophylaxis in high-risk patients

-no difference in clinical efficacy has yet been demonstrated between the individual preparations. low risk of HIT but should not be used in patients with HIT

Aspirin

The safety of neuraxial regional anaesthesia in patients receiving acetylsalicylic acid is mainly based on three studies [40–42]. Although the Collaborative Low-dose Aspirin Study in Pregnancy (CLASP)

LA toxicity

(Sep-2003 Q7) At the end of an open cholecystectomy, intercostal nerve blocks with a total of 20ml bupivacaine 0.5% are placed at two levels while the patient is still under general endotracheal anaesthesia. The patient develops ventricular fibrillation within 3 minutes. Describe your management of this situation.

The patient has received 20x5mg =100mg of bupivacaine and the weight of the patient is not known here but given the short duration prior to cardiac arrest, the most likely differential in this situation is cardiovascular collapse from LA toxicity. Other less likely differentials would be a acute coronary event due to underlying ischaemic heart disease or arrhythmias.
The immediate management of this patient will include resuscitation according to BCLS protocols while maintaining the airway and breathing by leaving the patient intubated, 100% O2 and commencing CPR and defibrillation. IV adrenaline boluses 1mg of 100mcg/ml dilution and magnesium may be given. ?phenytoin.

Lipofundin as been shown to be effective in ???? it is available as given via a large bore IV line as a rapid bolus of 100ml followed by 400ml

The surgical team and family has to be informed and the patient admitted to SICU after successful resuscitatoin. ? maintainence lipofundin?Incident reporting and post event counselling.

intralipid/ lipid rescue

use in LA toxicity with cardiac arrest especially bupivacaine (CC:CNS ratio?)
functions as a 'lipid sink' for lipophilic agents


resus according to BCLS protocols-lipid rescue-post op icu monitoring

Contents:
Purified soybean oil 200 g
Purified egg phospholipids 12 g
Glycerol anhydrous 22 g
Water for injection q.s. ad 1000 mL
pH is adjusted with sodium hydroxide to approximately pH 8.
Energy content/L: 8.4 MJ (2 000 kcal).
Osmolality (approx.): 350 mOsm/kg water. 500ml bottle: first 100ml over 15 min then 400ml over

protocol:.5ml/kg as initial bolus, then 0.25ml/kg/min for 30-60 mins
In actual resuscitation for a 70kg person: 100ml as bolus then 400ml over the next 15mins

http://www.lipidrescue.org/

TOW the blocks

neuraxial

peripheral

truncal: paravertebral
superficial and deep cervical plexus
brachial plexus
upper limb nerves
wrist block

lumbar plexus
femoral nerve
sciatic nerve-popliteal
ankle block