Clinical Anaesthesiology

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Clinical Anaesthesiology

• Qiu Wei Fan
• Associate professorDepartment of
  AnaesthesiologyRui Jin HospitalShanghai Second
  Medical University

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Local Anaesthetic techniques

• Features of local anaesthesia
• Methods of local anaesthesia
• Complications of local anaesthesia
• Regional block equipment
• Spinal, epidural, caudal blocks
• Peripheral nerve blocks

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Preoperative assessment and premedication
Purpose

• Establish rapport with the patient
• Obtain a history and perform a physical
  examinations
• Order a special investigations
• Assess the risks of anaesthesia and surgery and
  if necessary postpone or cancel the date of
  surgery
• Instutite preoperative management
• Prescribe premedication and the anaesthesia
  management

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Preoperative assessment and premedication

• Routine preoperative anaesthetic evaluation
• History
• Current problem
• Other known problems
• Medication history

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Preoperative assessment and premedication
Medication history

• Allergies
• Drug intolerances
• Present therapy
• Prescription
• Nonprescription

• Nontherapeutic
• Alcohol
• Tobacco
• Illicit

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Preoperative assessment and premedication

• Previous anaesthetics, surgery, and obstetric
  deliverries
• Family history
• Review of organ systems
• Last oral intake

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Preoperative assessment and premedication
Review of organ systems

• General
• Respiratory
• Cardiovascular
• Renal
• Gastrointestinal
• Hematologic

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Preoperative assessment and premedication
Review of organ systems

• Neurologic
• Endocrine
• Psychiatric
• Orthopedic
• Dermatologic

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Preoperative assessment and premedication
Physical examination

• Vital signs
• Airway
• Heart
• Lungs
• Extremities
• Neurologic examination

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Preoperative assessment and premedicationLaborat
ory evaluation

• Hematocrit or hemoglobin concentrationAll
  menstruating womenAll patients over 60 years of
  ageAll patients who are likely to experience
  significant blood loss and may require
  transfusion
• Serum glucose and creatinine (or blood urea
  nitrogen) concentration all patients over 60
  years of age
• Electrocardiogram all patients over 40 years of
  age
• Chest radiogram all patients over 60 years of
  age

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ASA classification

• I A normal healthy patient other than surgical
  pathology- without systemic disease.
• II A patient with mild systemic disease no
  functional limitations.
• III A patient with moderate to severe systemic
  disturbance duo to medical or surgical disease-
  some functional limitation but not
  incapacitating.

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ASA classification

• IV A patient with severe systemic disturbance
  which poses a constant threat to life and is
  incapacitating.
• V A moribund patient not expected to survive 24
  hours with or without surgery.
• E If the case is an emergency, the physical
  status is followed by the letter E-, IIE.

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American Society of Anaesthesiologists
classification and perioperative mortality rates

• Class Mortality Rate
• I 0.06-0.08 II
  0.27-0.4 III 1.8-4.3 IV
  7.8-23 V 9.4-51

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Documentation

• Informed Consent
• The preoperative note
• The intraoperative anaesthesia record
• The postoperative notes

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Local Anaesthetic techniques Features of local
anaesthesia

• Preservation of consciousness
• The quality of early postoperative analgesia
• Simplicity of administration
• Sympathetic blockade attenuation of the stress
  response
• Minimal depression of ventilation

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Local Anaesthetic techniques Methods of local
anaesthesia

• Surface anaesthesia
• Local infiltration
• Field block
• Regional blocks (Spinal, epidural, caudal
  blocks)
• Peripheral nerve blocks

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Complications of local anaesthesia

• Local anaesthetic toxicity( Systemic toxicity)
  Cardiovascular, Respiratory, Cerebral and
  Immunologic
• Hypotension
• Motor blockade
• Pneumothorax
• Urinary retention
• Neurological complications
• Equipment problems

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Local anaesthetic toxicity

• Systemic toxicity Cardiovascular
• Cardiac dysrhythmia or circulatory
  collapse is often the presenting sign of local
  anaesthetic overdose during anaesthesia.

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Local anaesthetic toxicity

• Systemic toxicity Respiratory
• Lidocaine depresses hypoxic drive. Apnea
  can result from phrenic and intercostal nerve
  paralysis or depression of the medullary
  respiratory center.

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Local anaesthetic toxicity

• Systemic toxicity Cerebral
• Early symptoms are circumoral numbness,
  tongue paresthesia, and dizziness. Sensory
  complaints may include tinnitus and blurred
  vision.Excitatory signs often precede central
  nerve system depression.

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Local anaesthetic toxicity

• Systemic toxicity Immunologic
• True hypersensitivity reactions to local
  anaesthetic agents- as distinct from systemic
  toxicity due to excessive plasma concentration-
  are quite uncommon.

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Regional block equipment

• Spinal needles (26G)
• Pencil-point 24G needles
• Catheters
• Label syringes
• A short length of tubing
• Nerve stimulators
• Local anaesthetic drugs

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Complications of local anaesthesia Hypotension

• Sympathetic blockade
• Total spinal blockade
• Vasovagal attack
• Anaphylactoid reaction

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Regional block

• Subarachnoid block(SAB) Spinal anaesthesia
• Extradural nerve block Epidural anaesthesia may
  be performed in the sacral(caudal block), lumbar,
  thoracic or cervical regions.

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Regional Block

• PhysiologySomatic BlackadeVisceral
  blackadeCardiovascularPulmonaryGastrointestinal
  LiverUrinary tractMetabolic Endocrine

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Physiology effects of SABDifferential nerve
blockade

• Sympathetic fibres block
• sensory block
• Motor block

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Physiology effects of SABRespiratory system

• Roots of the phrenic nerves apnoea
• Thoracic level loss of intercostal muscle
  activity, decrease in vital capacity, reduction
  in cardiac output and pulmonary artery pressure,
  and increased ventilation/perfution imbalance,
  resulting in a decrease in arterial oxygen
  tension (PaO2)

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Physiology effects of SABCardiovascular system

• Denervation of the sympathetic outflow tracts
  (T1-L2) dilatation of resistance and capacitance
  vessels and results in hypotension
• Bradycardia vasovagal syndrome block of the
  cardiac sympathetic fibres

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Physiology effects of SABGastrointestinal system

• Sympathetic denervation and unopposed
  parasympathetic action a constricted gut with
  increased peristaltic activity (nausea, retching
  or vomiting)

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Physiology effects of extradural block

• The physiological effect of extradural
  blockade are similar to those following
  subarachnoid block.

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Spinal anaesthesiaIndications

• Lower extremities
• Hip
• Perineum
• Lower abdomen
• Lumber spineType of surgery Urology,
  Gynaecology, Obstetrics and any surgical
  procedure on the lower limbs or perineum.
• Urologic endoscopic surgery, Rectal
  surgery, repair of hip fracture, obstetrics,
  orthopedic, Inguinal hernia repair, etc.

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Spinal anaesthesia Contraindications

• AbsoluteSepsisBacteremiaSkin infection at
  injection siteHypovolemiaCoagulopathyTherapeuti
  c anticoagulationDemyelating central nerve
  system diseaseIncreased intracranial
  pressurePsychosis or dementiaLack of consent

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Spinal anaesthesia Contraindications

• RelativePeripheral neuropathyMini-dose
  heparinAspirin or other antiplatelet drugsPrior
  lumbar spine surgeryChronic back painCertain
  cardiac lesionsPsychologic or emotional
  instabilityUncooperative patients Prolonged
  surgerySurgery of uncertain durationSurgical
  team resistance to awake patients

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Patient preparation

• Consent
• Physical examination
• Laboratory Tests
• Premedication

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Equipment Safety

• General Preparation Monitoring
• Administration of GA if necessary
• Resuscitation equipment
• Regional equipment

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Patient position

• Sitting position
• Lateral position
• Prone position

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TechniqueNeedle Technique

• Midline Technique
• Paramedian Technique

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Factors influencing spinal anaesthesia

• Agents Procaine, Tetracaine, Lidocaine,
  Bupivacaine
• Dosage
• Vasoconstrictors
• Specific Gravity Hyperbaric technique, Hypobaric
  technique, Isobaric technique
• Posture

• Intra-abdominal Pressure
• Spinal Curvature
• Prior Surgery of Spine
• Age
• Obesity
• Pregnancy
• Spread of the agent
• Redistribution

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Spinal anaesthesia Complications

• Pain on injection
• Backache
• Headache
• Urinary Retention
• Meningitis and meningism
• Vascular injury
• Nerve injury Cranial nerve palsy
• High spinal anaesthesia
• Transverse myelitis and cauda equina syndrome

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Epidural anaesthesia Indications

• Specific IndicationsHip and knee surgeryLow
  extremity RevascularizationObstetric
  deliveriesPostoperative management

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Epidural anaesthesia Contraindications

• Epidural anaesthesia shares the
  contraindications discussed in the section on
  spinal anaesthesia.

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Applied Physiology for Epidural Anaesthesia

• Segmental Blockade
• Differential Blockade

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Table Agents for epidural anaesthesia

• Agent Concentration Onset
  Sensory Block Motor Block
• Chloroprocaine 2
  Fast Analgesic Mild to moderate
  3 Fast
  Dense Dense
• lidocvaine 1
  Intermediate Analgesic Minimal
  1.5
  Dense
  Mild to moderate
  2 Intermediate Dense
  Dense
• Mepivacaine 1
  Intermediate Analgesic
  Minimal 2
  Intermediate Dense Dense
  
• Prilocaine 2
  Fast Dense
  Minimal 3
  Fast Dense
  Dense
• Bupivacaine 0.25 Slow
  Analgesic Minimal
  0.375-0.5 Slow
  Dense Mild to moderate
• 0.75
  Slow Dense Moderate
  to dense

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Technique of Epidural Anaesthesia

• A) Safety
• B) Preparation of the patientInformed
  consentPreoperative evaluationLaboratory
  assessmentPremedication
• C)Equipment The epidural needle

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Technical performance of a block

• Identification of the epidural space
• Loss of resistance technique
• Hanging drop technique

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Level selected

• Lumbar epidural anaesthesia Midline technique,
  paramedian technique
• Thoracic epidural anaesthesia Midline technique,
  paramedian technique
• Cervical epidural anaesthesia Midline technique

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Strategies for injection of the anaesthetic agent

• A test dose
• Incremental dosing

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Choice of local anaesthetic

• Agent Concentration
  Onset Sensory Block Motor Block
• Chloroprocaine 2
  Fast Analgesic Mild to
  moderate
  3 Fast Dense
  Dense
• lidocvaine 1 Intermediate
  Analgesic Minimal
  1.5
  Dense Mild
  to moderate
  2 Intermediate Dense
  Dense
• Mepivacaine 1
  Intermediate Analgesic
  Minimal 2
  Intermediate Dense
  Dense
• Prilocaine 2 Fast
  Dense Minimal
  3 Fast
  Dense Dense
• Bupivacaine 0.25 Slow
  Analgesic Minimal
• 
  0.375-0.5 Slow Dense
  Mild to moderate
• 0.75
  Slow Dense
  Moderate to dense

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Factors that affect epidural anaesthesia

• Dosage
• Patient Age
• Weight Height
• Posture
• Vasoconstrictors
• pH adjustment of local anaesthesia
• Failure of epidural block

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Epidural anaesthesia Complications(Intraoperative)

• Dural tap
• Total spinal anaesthesia
• Profound hypotension
• Apnoea
• Massive extradural block and subdural block
• Intravenous toxitity
• Hypotension
• Shivering
• Nausea/ vomiting

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Epidural anaesthesia Complications(Postoperative)

• Headache
• Infection
• Extradural haematoma
• Neurological complications

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Caudal anaesthesia Indications

• Obstetric patients, for vaginal deliveries
• Surgery related to the sacral area (anorectal and
  vaginal procedures).

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Caudal anaesthesia Contraindications

• The contraindications for caudal
  anaesthesia are the same as for any central block.

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Caudal anaesthesia Complications

• The complications of caudal block are
  essentially the same as those associated with
  epidural and spinal block.

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Differences between subarachniod and extradural
block

• Subarachniod Extradural block
• Small Large
• Fast Slow
• Complete anaesthesia Not complete
  anaesthesia
• Cord transection Dermatomal

• Dose of drug employed
• Rate of onset
• Intensity of block
• Pattern of block

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Peripheral nerve blocks

• Upper limb blocks
• Brachial plexus block
• Axillary block
• Supraclavicular block
• Interscalene block

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Peripheral nerve blocks

• Lower limb blocks
• Sciatic nerve block
• Femoral nerve block
• Mid tarsal block

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Question

• What are the complication of local anaesthesia?
• What are the features of local anaesthetic
  toxicity?
• What are the absolute contraindications to
  subarachnoid block and extradural block?

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Question

• What are the major differences between
  subarachnoid block and extradural block?
• How do you take the history from a patient?
• What are the methods for identifying the epidural
  space?

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Any Questions?

• Thank you !