Preparation and Initiation of Anesthesia

An ideal anesthetic technique would incorporate optimal patient safety and satisfaction, provide excellent operating conditions for the surgeon, allow rapid recovery, and avoid postoperative side effects. In addition, the chosen technique would be low in cost, allow early transfer or discharge from the post anesthesia care unit, optimize postoperative pain control, and permit optimal operating room efficiency, including turnover times. The anesthesia provider must evaluate the medical condition and unique needs of each patient, select an acceptable anesthetic technique, and make this recommendation to the patient.

Preparation for Anesthesia

  • Never induce anesthesia when alone with the patient trained assistant must be available.
  • Before starting, check that you have the correct patient scheduled for the correct operation on the correct side, by using modified/ WHO surgical patient safety checklist.
  • Check that the patient has been properly prepared for the operation and has had no food or drink for the appropriate period of time. It is normal to withhold solid food for eight hours preoperatively, but a milk feed can be given to babies up to four hours preoperatively. Clear fluids are regarded as safe up to three hours preoperatively if gastric function is normal.
  • Measure the patient's pulse and blood pressure, and try to make him or her as relaxed and comfortable as possible.
  • Before you give an anesthetic and going a critical moment make sure checked and functional of the following items.
    • All the apparatus you intend to use, or might need, is available and working
    • If you are using compressed gases, there is enough gas and a reserve oxygen cylinder is available.
    • Functional monitoring( oximetry, BP, EKG)
    • The anesthetic vaporizers are connected,
    • The breathing system that delivers gas to the patient is securely and correctly assembled
    • Breathing circuits are clean and functional
    • Resuscitation apparatus is present and working
    • Laryngoscope, tracheal tubes and suction apparatus are ready and have been decontaminated
    • Needles and syringes are sterile: never use the same syringe or needle for more than one patient
    • Any other drugs which are necessary for anesthesia , emergency you might need are in the room
  • Always begin your anesthetic with the patient lying on a table or trolley that can be rapidly tilted into a head-down position in case of sudden hypotension or vomiting.
  • Before inducing anesthesia, always ensure appropriate size of cannula in a large vein is available and working properly
  • Regional anesthesia needs the same preparation as of general anesthesia in addition to spinal needle, aseptic solutions, and drapes.

Initiation of anesthesia (Induction):

General anesthesia may be initiated by the administration of Parenteral drugs or inhalation of a volatile anesthetic (Table 2.1). General anesthesia renders a patient insensible to pain (analgesia); make the patient unaware of the procedure (amnesia); and muscle relaxation for surgical purposes. Vigilance, to be alert to danger or threats, is essential during the administration of general anesthesia. During general anesthesia the patient is reliant upon the anesthetist to maintain a patent airway, provide adequate oxygenation, and support of adequate heart function and other vital organ function.

Table 2.1 General Anaesthetic Techniques

Type Techniques
Mask anaesthesia
(including laryngeal mask)
  • Induction inhalational, intravenous or intramuscular.
  • Maintenance of anesthesia during surgery with the patient breathing spontaneously using an air/O2/inhalational agent
Endotracheal anesthesia
  • Induction either intravenous ( e.g. Ketamine 1-2 mg/kg or Thiopentone 3-5 mg/kg I.V.) or inhalational (Halothane)
  • Intubation using an IV muscle relaxant (suxamethenium 1-2 mg/kg I.V) or an inhalational agent, tube position confirmed with chest excretion and auscultation of breath sounds in both lungs
  • Maintenance during surgery either with spontaneous respiration as for mask anaesthesia or intermittent positive pressure ventilation (IPPV) using a long acting muscle relaxant (e.g. Vecuronium .05 - .1 mg/kg I.V) in addition to air/O2/inhalational agent +/- IV analgesia (e.g. Pethedine .5 - 1mg/kg I.V.)
  • Reversal of the muscle relaxation at the end of surgery (Neostigmine + Atropine)
Total intravenous anesthesia It is a technique of general anesthesia using combination of agents given solely by the intravenous route and in the absence of inhalational agents.
Monitored anesthesia care (MAC) or Conscious sedation
  • It refers to the anesthesia personnel present during a procedure and does not implicitly indicate the level of anesthesia needed. Administration of sedatives, analgesics, hypnotics, anesthetic agents or other medications as necessary to ensure patient safety and comfort
  • MAC is a specific anaesthetic service for diagnostic or therapeutic procedures.
  • Indications for monitored anesthesia care include the nature of the procedure, the patient's clinical condition and/or the potential need to convert to a general or regional anaesthetic.
  • MAC may include varying levels of sedation, analgesia, and anxiolysis as necessary. Monitoring of vital signs, maintenance of the patient's airway and continual evaluation of vital functions.
  • The provider of MAC must be prepared and qualified to convert to general anesthesia when necessary.
Balanced anesthesia
  • The concept emphasized the use of multiple drugs to produce unconsciousness and analgesia, provide skeletal muscle relaxation, and prevention of reflex responses.
  • No single anesthetic drug could provide all the characteristics of an ideal general anesthesia, but a combination of intravenous analgesics (e.g., pethedine), neuromuscular blocking drugs (e.g., pancuronium), and hypnotics (thiopentone) given together produced the desired balanced anesthetic.
  • Lower doses of each drug could be used because the different drugs tended to act synergistically.

Intravenous induction of general anesthesia the administration of anesthetic drugs (propofol, thiopental, or ketamine) to produce rapid onset of unconsciousness it is usually used in adult patients by the intravenous administration of an anesthetic that produces. Then, ventilation can be sustained via a face mask or a laryngeal mask air-way (LMA) may be inserted or a neuromuscular blocking drug may be given intravenously to facilitate direct laryngoscopy before tracheal intubation.
Intramuscular Induction

Anesthetic drugs can be administered intramuscularly. Uncooperative children are often anesthetized with drug given by this route. The drug that is given most often by intramuscular route is ketamine (5 to 10mg/kg, induction occurs within a few minutes (3 to 4 minute), followed by 10-15 minutes of surgical anesthesia.

Inhalation Induction

The administration of volatile anesthetics (e.g., halothane) through a mask to induce general anesthesia. Often used in the pediatric population. After an inhaled induction of anesthesia, a depolarizing (suxamethonium 1-2 mg/kg) or nondepolarizing neuromuscular blocking drug (Vecuronium 0.08- 0.1 mg/kg) is administered intravenously to provide the skeletal muscle relaxation needed to facilitate direct laryngoscopy for tracheal intubation. If endotracheal intubation is not accomplished, anesthesia can be maintained by inhalation via a facemask or laryngeal mask airway (LMA)

Last modified: Tuesday, 15 November 2016, 12:53 PM