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LOCAL ANASTHESIA
Q1) what are the types of local anesthetics and the differences?
A- Ester, Unstable in solution, Rapidly hydrolyzed in the body by plasma
cholinesterase & other esterases, associated with allergic phenomena
B- Amid, Stable in solution, Slowly metabolized by hepatic amidases,
hypersensitivity reactions are extremely rare
Q2) what are the CVS toxicity effect of local anesthetics ???
Early or mild toxicity:
If with Adrenaline tachycardia & Hypertension
If no Adrenaline bradycardia & hypotension
Severe toxicity:
Collapse (e.g. Bupivacaine)
Severe and intractable arrhythmias can occur with accidental iv injection.
Q3) how to treat local anesthetics toxicity?
according to the ABCD protocol to check the airway and give patient oxygen in high
concentration then to check breathing and ventilate the patient and here intubation
may be needed then correct circulatory failure by IV fluids and vsopressors like
ephedrine or adrenaline if lastly treat seizure by diazepam and thiopental
Toxic index of local ansthesia agents
Maximum
Drug
Dose (mg/kg)
5
Mepivacaine
2.5
Bupivacaine
5
Etidocaine
7
Procaine
8-9
Chloroprocaine
1.5
Tetracaine
5 0r 7
Lidocaine
with epinephrine
Q4) how prevent local anesthesia toxicity?
secure intravenous access before injection of any dose that always have adequate
resuscitation equipment and drugs available before starting to injection
Q5) What do if toxicity happen?
stop injuction and assess the pt
call for help
ensure an adequate airway give O2 in over facemask
ventilation the pt if there is inadequate spontaneous respiration
intubation if pt is unconscious and unable to maintain an airway
Q6) Mention the complications of the local anesthesia?
Needle Breakage, Pain on Injection, Burning on Injection,Persistent Anesthesia or
Parasthesia ,Trismus , Hematoma ,Infection, Edema, sloughing of tissue, soft tissue
injury,complication from nerve block(facial nerve paralysis)
Q7) Talk about local anesthesia toxicity ?
CNS (occur earlier)
Early: dizziness, tinnitus, confusion, drowsiness,circumoral numbness.
Severe: tonic-clonic convulsion leading to progressive LOC, coma, Resp depress &
resp. Arrest.
CVS:
Severe: collapse (due to effect of LA acting directly on the myocardium)
- How to treat CNS complications?
Iv fluid ,CAB, adrenaline
Q8) what is the maximam dose for Lidocaine?
- In normal healthy adults, the maximum recommended dose of:
Lidocaine + Adrenaline = 7mg/kg , total 700mg.
Lidocaine w/o Adrenaline= 4.5 mg/kg , total 300mg.
Q9) Treatment of seizures after Bier's block?
Treat Convulsions with anticonvulsant drugs (Diazepam 0.2-0.4mg/kg,
Thiopentone 1-4 mg/kg).
Q10) Name the local anesthetic that is most commonly used?
Lidocaine is the most commonly used local anesthetic for a wide range of procedures.
:‫بعض التوضيح‬
Amide: Lidocaine (Xylocaine) and bupivicaine (Marcaine) are the most commonly
used agents for local infiltration and field and nerve blocks. Amides are metabolized
in the liver.
Ester: The most commonly used ester, tetracaine, is used as a topical anesthetic.
Esters are metabolized by cholinesterase inhibitors in the plasma.
Q11) Whats the structure of local anesthesia <LA> agent?
A tertiary amine
Aromatic ring
Intermediate chain
Q12) Whats the mode of action of LA agent?
After injection, the tertiary amine base is liberated by the relatively alkaline pH of
tissue fluids, the effects are due to blockade of sodium channels, thereby
impairing sodium ion flux, across the membrane.
Q13) whats the main difference between Ester LA and Amide LA agent?
Ester
Amide
Unstable in solution
Stable in solution
Rapidly hydrolysed in the body by
plasma cholinesterase & other esterases
Slowly metabolised by hepatic amidases
One of the main breakdown products is
para-amino benzoate (PABA) which is
associated with allergic phenomena and
hypersensitivity reactions
hypersensitivity reactions are extremely
rare
In current clinical practice esters have
largely been superseded by the amides.
Q14) Examples of local anesthetic agents and its side effects.
1: Topical Anaesthesia
LA may be applied to the skin, the eye, the ear, the nose and the mouth as well as
other mucous membranes. most useful and effective: Lidocaine (i.e.gel 2%) and
prilocaine(i.e.EMLA)
2: Infiltration Anaesthesia
provide anaesthesia for minor surgical procedures. commonly used Amide LA are
(Lidocaine prilocaine,mepivacaine and Bupivacaine). The site of action is at
unmyelinated nerve endings and onset is almost immediate
3: Intravenous regional anaesthesia (IVRA) IVRA (BIER s Block) analgesia for
minor surgical procedures. The local anaesthetic agent is injected into a vein of a limb
that has been previously exsanguinated and occluded by a tourniquet.
The site of action is probably the unmyelinated nerve fibres, Prilocaine and Ldocaine
are commonly used.
Bupivacaine and etidocaine should never be used for IVRA! They are
significantly protein bound and once the tourniquet is released there is a risk of
cardiotoxicity. Several deaths have been reported during IVRA with bupivacaine.
4: Peripheral Nerve Blockade :
Regional anesthetic procedures that inhibit conduction in fibers of the peripheral
nervous system. It can be devided into:
- Minor nerve blocks involve the blocking of single nerve
entities such as the inferior alveolar nerve, mental nerve, ulnar or radial nerve.
- Major nerve blocks involve the blocking of deeper nerves or trunks with a wide
dermatomal distribution (e.g. brachial plexus blockade).
The commonly used LA agents are: Lidocaine, prilocaine, mepivacaine, and
bupivacaine.
5: Extradural Anaesthesia:LA agent injected in the
epidural space between the dura mater and the Lig.Flavum. usually used mainly
isobaric Bupivacaine 0.5% or lidocaine (2.0%)
6: Spinal Anaesthesia injction
directly into the cerebrospinal fluid (subarachnoid space) produces spinal anaesthesia.
commonly used : mainly hyperbaric Bupivacaine 0.5% or lidocaine (5%)
Q15) Hypertensive and diabetic PTN needs a surgery for inguinal hernia, what
type of anesthesia would you advice?
Regional anesthesia
Q16) Where should you insert the needle for this type of anesthesia?
Below L2 n above first sacral
Q17) what is the maximam dose for Lidocaine?and why do we increase the dose
with Adrenaline??
 The maximum recommended dose of lidocaine
injection without epinephrine should not exceed 4.5 mg/Kg, and the maximum
total dose should not exceed 300 mg. Once given the maximum dose of
lidocaine, it should not be repeated for 2 hours.
 In normal healthy adults, the maximum recommended dose of lidocaine
injection with epinephrine for local anesthesia other than spinal should not
exceed 7 mg/Kg
 Epinephrine causes local vasoconstriction which limit local spread of the drug
and therefore allowing a larger dose of drug to be infiltrated without causing
systemic toxicity.
Q18) the mode of metabolism of esters local anesthetics?
Amino esters and amino amides differ in several respects. Amino esters are
metabolized in the plasma via pseudocholinesterases, whereas amino amides are
metabolized in the liver. Amino esters are unstable in solution, but amino amides are
very stable in solution. Amino esters are much more likely than amino amides to cause
allergic hypersensitivity reactions
Q19) 30 y old male COPD ,no cadio problem, no DM ,came for femoral
hernia,what type of anesthesia you give and why?
 I think spinal anesthesia ??
- what are the signs of Cardiac arrest ?
 Sudden loss of responsiveness (no response to tapping on shoulders).
No response to tapping on shoulders.
Does nothing when you ask if he's OK. With no pulse.
Spinal Anesthesia
Epidural Anesthesia
Q20) what are the layers u go through?
- The drugs injected into the
subarachnoid space (directly to
the L2 level in the CSF)
- Identification of subarachnoid
space is when CSF flowing out
- Rapid onset of action (2-5
minutes)
- Cause spinal headache
- The drug injected into epidural
area (between dura and
periosteum of vertebra) at any
level of vertebral column
- Identification of peridural area is
when there is loss of resistance.
- longer onset of action (15-20
minutes)
- doesn’t cause headache
the structures that will be passed skin , subcutaneous tissue, supraspinous ligament ,
interaspinous ligament , lagementum flavum , dura mater
Q21) complications of spinal anesthesia
 Hypotension : due to vasodilatation and a functional decrease in the effective
circulating volume.
 Headache : within 12-24 h and may last for 1 week.
 Urinary retention : the sacral autonomic fibers are among the last to recover.
 Permanent neurological complications (rare): meningitis, arachnoiditis ,
peridura abscess
 Permanent paralysis: in elderly patient
 other cause: direct injury of the spinal cord
Q22) What do you know about epidural anesthesia
LA solution deposited in the peridural space(between dura mater & periousteum lining
the vebt. Canal)
..why we give a larger dose than the spinal ?
space is larger for an epidural, and subsequently the injected dose is larger, being
about 10-20 ml in epidural anesthesia compared to 1.5-3.5 ml in a spinal.
..whats in the epidural space ?
contains lymphatics, spinal nerve roots, loose fatty tissue, small arteries, and a
network of large, thin-walled blood vessels
and what's in the subarachnoid space ?
CSF
Q23) what are the layers when do epidural anesthesia from outside to inside?
the structures that will be passed skin  SC tissue  supraspinous ligament 
interaspinous ligament  lagementum flavum  epidural space
Q24) What the color of ligamentum flavum?
yellow
Q25) What are the difference between spinal and epidural <Anatomically>?
In spinal anesthesia we puncture the dura matter but in epidural we don’t
Q26) define epidural anesthesia?
Local anesthetic solution are deposited in the epidural space between Dura mater and
periosteum lining the vertebral canal
Q27) define local anesthesia?
be defined as drugs, which are used clinically to produce reversible loss of sensation in
a circumscribed area of the body.
Q28) what drugs can be used in spinal anesthesia ?
Bupivacaine and Lidocaine.
Q29) Epidural Technique, types of drugs used for epidural anesthesia and the
signs of toxicity?
— Local anaesthetic solutions are deposited in the peridural space between the
dura mater and the periosteum lining the vertebral canal. The peridural space
contains adipose tissue, lymphatics and blood vessels. The injected local
anaesthetic solution produces analgesia by blocking conduction at the intradural
spinal nerve roots.
— Technique:
Loss of resistance technique to identify the epidural space.
0.5% Bupivacaine (mainly) or lidocaine (2.0%) is usually used to produce
epidural anaesthesia
......
Toxicity signs :
excitation: nervousness, tingling around the mouth, tinnitus, tremor, dizziness,
blurred vision, or seizures, followed by depression: drowsiness, loss of
consciousness, respiratory depression and apnea
Q30) Contraindication cases in spinal anesthesia?





abnormal bleeding and clotting parameters, liver disease, patients receiving
anticoagulants such as Warfarin or Heparin
Patient refusal for the administration,
Anatomical difficulties
Presence of neurological disease, infection of skin
Uncooperative patients such as children, mentally challenged individuals,
patients with psychiatric disorders
Q31) If we remove the tourniquet after 10 min in bier's and the pt. is unstable,
what are the causes?
o
Complications are due to toxicity of local anesthesia ,occur if tourniquet
suddenly deflate soon after injection of LA
Q32) What will happen first: CNS complications or CVS? Why?
o
CNS complications, because the CNS has lower threshold and it has
greater blood perfusion.
Q33) What are the doses of drugs used in bier's block?
o
ARM: 30-40ml of 0.5% prilocaine or 0.5% lidocaine)
o
LEG :50-60mlof 0.5% prilocaine or 0.5% lidocaine)
Q34) When we should remove the tourniquet after bier's blocker?
o
At least after 20 minutes
Ans.1 The spinal anesthesia, in the CSF, the epidural anesthesia is Local
anaesthetic solutions deposited in the peridural space between the dura mater
and the periosteum lining the vertebral canal.
Q35) on which level we do epidural
(10-11)
Q36) what do you know about epidural anesthesia
LA solution deposited in the peridural space(between dura mater & periousteum lining
the vebt. Canal)
..why we give a larger dose than the spinal ?
space is larger for an epidural, and subsequently the injected dose is larger,
being about 10-20 ml in epidural anesthesia compared to 1.5-3.5 ml in a spinal.
..whats in the epidural space ?
contains lymphatics, spinal nerve roots, loose fatty tissue, small arteries, and a
network of large, thin-walled blood vessels
and what's in the subarachnoid space ?
CSF
Q37) Technique of bierr's block
The double tourniquet applied to the upper arm or thigh (Never placed on the forearm
or lower leg as adequate arterial compression cannot be obtained)
1. More effective block by tightly wrapping the distal part of the limb with an
ESMARCH rubber bandage before inflating tourniquet
2. The proximal tourniquet is then inflated to a pressure of 50 to100 mmHg
above patient systolic BP
3. Remove the rubber bandage
4. The local anesthetic solution is then slowly injected into the indwelling cannula
and the patient warned that the limb may start to feel hot and mottled skin
appearance, analgesia occur within 3-5 min
5. Inflate the distal tourniquet
6. Deflate the proximal <<the patient complain of pain due to pressure from
it>>>>>…the surgery start
7. At the end of the procedure, the tourniquet is deflated and normal sensation
quickly returns.
-Even if the surgery is completed within a few minutes, on no account should the
tourniquet be deflated until at least 20-30 minutes has passed since the injection
of the local anaesthetic or serious toxic side-effects may occur
Q38) Doses of local anaethetic in beir's block?
•
Arm: 30-40ml of 0.5% prilocaine or 0.5% lidocaine.
• Leg :50-60ml of 0.5% prilocaine or 0.5% lidocaine.
Q39)- Treatment of seizures after Bier's block ?
100% O2
IV access
Ephedrine
Benzodiazepine
Q40) What is the most important step of Bier's block.
completeness of the exsanguination as the blood is being squeezed from the vascular beds
into the proximal circulation(not sure)