Practical conduct of anaesthesia.

• Planning the conduct of anaesthesia

  Starts normally after details concerning the surgical procedure and the medical condition of the patient have been ascertained at the preoperative visit
• Preparation for Anaesthesia


  • Consideration of induction and maintenance of anaesthesia
  • The position of the patient on the operating table
  • Equipment necessary for monitoring
  • The use of Intravenous fluids or blood for Infusion
  • Post operative care and recovery facilities which will be required
• The availability and function of all anaesthetic equipments should be checked before starting
• After the patient's arrival in the Induction room the anaesthetist should be satisfied that the correct operation is being performed upon correct patient and that consent has been given
• Patient


  • Must be on tiltable bed or trolley
  • Anaesthetist should have a competent assistant
• Equipment required for tracheal Intubation

  • Correct size of laryngoscope and spare (in case of light failure)
  • Tracheal tube of correct size and an alternative smaller size
  • Tracheal tube connector
  • Wire stilette
  • Gum elastic bougies
  • Magil forceps
  • Cuff Inflating syringe
  • Artery forceps
  • Securing tape or bandage
  • Catheter mount
  • Local anaesthetic spray – 4% Lignocane
  • Cocaine spray/ gel for nasal Intubation
  • Tracheal tube Lubricant
  • Throat packs
• Anaesthetic breathing system and facemask – tested with 02 to ensure no leaks present
• Techniques for Induction of Anaesthesia

  • Inhalational Induction
  • Intravenous Induction
• Inhalational Induction


  Indications: Young children, Upper airway obstruction eg epiglotitis, Lower airway obstruction with foreign body, Bronchopleural fistula or empyema, No accessible veins. 70% N20 in oxygen is used as maintenance and anaesthesia depened by the gradual introduction of increments of a volatile agent e.g. Halothane, enflurane, Isoflurane. Maintenance levels of halothane 1-2%, Enflurane 1.5-2.5%, or Isoflurane 1-2%
• Difficulties and complications of Inhalational Induction

  • Slow Induction of anaesthesia
  • Airway obstruction, bronchospasm
  • Laryngeal spasm, hiccups
  • Environmental pollution
• Intravenous Induction


  Most appropriate method of rapid induction
• Intravenous Induction Protocols


  • STP = 3-5 mg/kg
  • Methohexitone 1-1.5 mg/kg
  • Etomidate 0.3mg/kg
  • Katamine 2mg/kg
• Complications and Difficulties of Intravenous Induction

  • Regurgitation and vomiting
  • Intra-arterial injection of thiopentone
  • Perivenous Injection
  • Cardiovascular depression
  • Respiratory depression
  • Histamine release; Methohexitone or STP
  • Porphyric: Acute porphyric episode may be precipitated by barbiturate in susceptible individual
  • Other complications: pain on injection (especially with methohexitone, etomidate or propofol), hiccup or muscular movement may occur
• Patient Positions for Surgery

  • Lithotomy
  • Lateral Position
  • Prone position
  • Trendelenbing
  • Sitting position
  • Supine position
• Lithotomy Position


  • May result in nerve damage on the medial and lateral side of the leg from pressure exerted by the stirrups, which must be well padded. Elevate both legs simultaneously, to prevent pelvic asymmetry and resultant backache. Support sacrum on the operating table to prevent slipping off
• Lateral Position


  • May result in asymmetrical lung ventilation. Care is required with arm position and I.V infusions. Pelvis must be supported to prevent the patient from rolling either backwards or forwards into the recovery position
• Prone position


  • Upward pressure on the diaphragm because of the weight of the abdominal contents. Damage to the brachial plexus may occur as a result of pressure from shoulder support, especially if the arms are abducted
• Sitting position


  • Careful support of head. Venous pooling and resultant cardiovascular instability may occur
• Supine position


  • Supine hypertensive syndrome during pregnancy or in patients with a large abdominal mass
• Techniques for Maintenance of Anaesthesia

  • Inhalational agents
  • i.v Anaesthetic agents
  • iv opioids
  • Tracheal Intubation with or without muscle relaxant
  • Regional anaesthesia
• Inhalational Anaesthesia with spontaneous ventilation

  Appropriate form of maintenance for superficial operation
• Factors affecting Minimum Alveolar Concentration (MAC)

  • Halotheme 0.8%
  • Isoflurane 1.15%
  • Enflurane 1.68
  • N20 105
• Indications for Inhalational Anaesthesia with spontaneous ventilation

  Minor procedure which produce little reflex or painful stimulation. Operation for which profound muscle relaxation is not required
• Stages of Anaesthesia


  • Stage 1 Analgesia
  • Stage 2 Stage of excitement
  • Stage 3 Surgical Anaesthesia
  • Stage 4 Stage of impending respiratory and circulatory failure
• Stage 1 Analgesia


  • Stage attained when using N20 50% in oxygen as employed in the technique of relative analgesia
• Stage 2 Stage of excitement

  • Seen with Inhalational Induction, but rapidly passed during i.v induction. Resp is erratic, breath holding may occur. Laryngeal and pharyngeal reflexes are active. Stimulation of pharynx or larynx may produce laryngeal spasm. Loss of eyelash reflex, but the eyelid reflex remain present
• Stage 3 Surgical Anaesthesia

  • Deepens through 4 planes (in practice 3 – light, medium, deep). Respiration assume a rhythm pattern and the thoracic component diminishes with depth of anaesthesia. Respiratory reflexes become suppressed but the carina reflex is abolished only at plane IV. Pupils are central and gradually enlarge with depth of anaesthesia. Lacrimation is active in light planes but absent in planes iii & iv – a useful sign in a patient not premedicated with an anticholinegic
• Stage 4 Stage of impending respiratory and circulatory failure


  • Brain stem reflex s are depressed by the high anaesthetic concentration. Pupils are enlarged and unreative. Patient should not be permitted to reach this stage
• Withdrawal of the anaesthetic agents and administration of 100% oxygen lightens anaesthesia
• Swallowing


  • Occurs in the light plane of stage 3
• Gag reflex


  • Is abolished in upper stage 3
• Stretching of the anal sphincter

  • Produces reflex laryngospasm even at plane III of stage 3
• Complications / difficulties during Inhalational anaesthesia

  • Airway obstruction
  • Laryngeal spasm
  • Bronchospasm
  • Malignant hyperpyrexia
  • Raised intracranial pressure (ICP)
  • Atmospheric pollution
• Airway maintenance devices


  • Oropharygeal airway (Guedel airway)
  • Nasopharyngeal airway
  • Face masks
  • Nose masks
  • LMA ( Laryngeal Mask Airway )
  • Clausen harness
• Tracheal Intubation


  Provision of a clear airway, e.g. Anticipated difficultly in using mask anaesthesia in the edentulous pt. An unusual position, e.g. prone or sitting. Operations on the head and neck e.g ENT, dental. A nasotracheal tube may be required. Protection of the respiratory tract e.g. from blood during URT or oral surgery and from inhalation of gastric contents in emergency surgery or pt with oesophageal obstruction. During anaesthesia using IPPV and muscle relaxants. To facilitate suction of the respiratory tract. During thoracic surgery. Reinforced tube with nylon or steel
• Complications of tracheal Intubation

  • Early complications: Trauma to lips and teeth or dental crowns, jaw dislocation and dislocation of arytenoids, Nasal Intubation: epistaxis, trauma to the pharyngeal wall or dislodgment of adenoid tissue, Obstruction or kinking of the tube, Carina stimulation or bronchial Intubation, Laryngeal oedema may produce postop croup, bronchospasm or layngospasm, especially in children, Cardiovascular complications of Intubation Include arrhytmias and hypertension especially in untreated by hypertensive patient
  • Late complications: Tracheal stenosis, Trauma to vocal lords may result in ulceration or gramulomata which may required surgical removal, Cord trauma may be more common in the presence of an URTI
• Indications for relaxant anaesthesia

  • Major abdominal
  • Intra peritoneal
  • Thoracic Operation
  • Intracranial
  • Abnormal positions
• Relaxant Anaesthesia


  An alternative to deep anaesthesia with spontaneous ventilation and volatile agents leading to multisystem depression. Relaxation anaesthesia provides muscle relaxation permitting lighter anaesthesia with risk of cardiovascular depression
• Reversal agents


  • Neostigmine 0.05 – 0.08 mg/kg in children 2.5 – 5mg in adult
  • Atropine 0.02mg/kg= 1.2mg
  • Glycopyrolate 0.5mg
• Give atropine before or with the neostigmine