essay 16 - General anesthesia in oral surgery. Types of anesthetic agents. Management and guidance of anesthesia. Complications, prevention.

define general anaesthesia

• a controlled, reversible state of unconsciousness induced by drugs. It allows oral surgeons to perform procedures that would otherwise cause unbearable pain, severe physiological stress and unpleasant memories.

what is balanced anaesthesia and what are its characteristics?

• balanced anaesthesia combines inhalation + IV drugs + opioids + Muscle relaxants

• characteristics:

1. amnesia - no memory

2. analgesia - no pain

3. muscle relaxation/ paralysis - to suppress reflexes and allow surgical access

4. sedation/ unconsciousness - unarousable, even to pain

5. loss of protective reflexes and spontaneous ventilation

advantages of general anaesthesia

• reduces intraoperative patient awareness and recall

• allows proper muscle relaxation for long periods of time

• facilitates complete control of the airway, breathing and circulation

• can be used in cases of sensitivity to local anaesthetic agent

• can be administered without moving the patient from the supine position

• can be adapted easily to procedures of unpredictable duration or extent

• can be administered rapidly and is reversible

disadvantages of general anaesthesia

• requires increased complexity of care and associated costs

• require some degree of preoperative pain preparation

• induce physiological fluctuations that require active intervention

• associated with less serious complications such as nausea or vomiting, sore throat, headache, shivering and delayed return to normal mental functioning

• associated with malignant hypothermia, a rare, inherited muscular condition in which exposure to some (but not all) general anaesthetic agents results in acute and potentially lethal temperature rise, hypercarbia (more than the normal level of carbon dioxide in the blood), metabolic acidosis and hyperkalemia

list The types of anaesthetic agents

• induction agents (to induce anaesthesia)

• Opioid analgesics (for pain control)

• Muscle relaxants (neuromuscular blocking agent)

describe the induction agents

1. IV Agents:

• propofol (non barbituate, fast onset, less postoperative nausea, clear headed recovery)

• thiopental (barbituarte, rarely used now)

• etomidate, ketamine (used especially in children or shock)

2. inhalation agents

• enter through Long Than I carried my blood to the body tissue. commonly used in combination with intravenous anaesthetic

• sevoflurane (non irritating, good for inhalation induction)

• desflurane (rapid recovery but irritates airway)

• halothane (pleasant smell so it's better to use for children, provides little pain relief, maybe toxic to adult liver, no longer Commonly used)

• nitrous oxide (fast as induction and recovery time, week often used with other agents)

describe the opioid analgesics (for pain control)

• fentanyl, morphine, sufentanil, remifentanil

describe the muscle relaxants (neuromuscular blocking agents)

• succinylcholine (rapid, short acting, depolarizing)

• rocuronium, vecuronium, atracurium (Non depolarizing)

what are the different phases of management of anaesthesia

1. premedication Phase (pre-op)

2. induction phase

3. maintenance phase

4. emergence phase (recovery)

describe the premedication phase - management and phases of anaesthesia

1. goal = calm, relax patient, reduced anxiety and minimal recollection

2. Agents =

• Midazolam (benzodiazepine, anxiolytic)

• NSAIDs or paracetamol (for pre-emptive pain control)

• Antacids, H2 blockers if reflux history

• Atropine/scopolamine only if fiberoptic endotracheal intubation anticipated

describe induction- management and phases of anaesthesia

1. goal = Transition Patient from Awake to anaesthetised smoothly

2. steps:

• check DAMMIS = drugs, airway, Machine, monitors, IV, suction

• induce with IV or inhalation drugs

• administer opioids

• secure airway Via:

— manual support (jaw lift) - esmarch handgriff

— Laryngeal mask airway (LMA) - simple, fewer complications but no protection against aspiration

— endotracheal intubation - if high risk of aspiration, prolonged surgery and muscle relaxants needed

Describe maintenance phase - management and phases of anaesthesia

1. Maintain Unconsciousness Using:

• inhalation agents (vapour) + mechanical ventilation if needed

• titrate depth according to surgical stimulus (Lighter During prep, deeper during incision/ manipulation)

• monitor autonomic signs (BP, heart rate, sweating) to adjust depth especially when patient is paralysed and cannot move

• avoid excessive depth (can lead to hypotension, bradycardia and delayed emergence)

Describe emergence Phase (recovery) - management and phases of anaesthesia

• reduce/ stop anaesthetics

• reverse muscle relaxants

• ensure spontaneous breathing

• remove airway devices only when patient can protect airway (cough, swallow)

management and guidance

• Assess airway risks (mallampati score, neck mobility, dentition, jaw saize)

• ensure empty stomach (to reduce aspiration risk) → no solids 6 hours prior, no clear liquids 2-4 hrs prior

• continue most regular medication (Exceptions: anticoagulants, metformin, Mao inhibitors)

list some common minor complications and how to prevent them

• sore throat, hoarseness (due to intubation trauma)

• post operative nausea and vomiting (ponv)

• headache, Shivering and Delayed return to normal function

list some serious complications and prevention

• awareness under anaesthesia → patient is paralysed but aware; prevent with careful monitoring (e.g BIS monitors)

• malignant hyperthermia → Rare, inherited, sudden high fever, acidosis, hyperkalemia after exposure to triggering anaesthetics (especially succinylcholine); requires immediate dantrolene administration

• anaesthetic toxicity → halophane (hepatotoxicity), sevoflurane (nephrotoxicity), Co formation in circuits (hemolysis)

• pulmonary aspiration (Mendelson syndrome) → chemical pneumonitis If stomach content enters lungs; prevent by fasting and using endotracheal tubes in high risk cases

• peripheral nerve injuries → ulnar, peroneal, brachial plexus injuries due to poor positioning; prevent with careful padding and regular cheques

what are some some special considerations in oral surgery - complications and prevention

• fear and anxiety are often the main indications for general anaesthesia, not just the complexity of the procedure

• for dental procedures, general anaesthesia should involve:

— dentist+ Anaesthesia Provider+ Assistant

— extra caution caution if done outside a hospital setting

— indications = extreme dental phobia, severe gag reflex and special needs patients