premedication, sedation

PREMEDICATION, SEDATION AND GENERAL ANAESTHESIA

Presented by: Dr. Otasowie D. Osunde, BDS, PhD, FWACS, FAOCMF

OUTLINE

  • Premedication

  • Route of Administration and Drugs Used for Premedication

  • Sedation Techniques

  • Relative Analgesia

  • General Anaesthesia in Dentistry

  • Complications of General Anaesthesia

PREMEDICATION

  • Definition: Premedication refers to the use of drugs typically administered 1–2 hours before surgical procedures to reduce anxiety and enhance sedation.

Objectives of Premedication:

  • Relief of apprehension or anxiety.

  • Induction of sedation.

  • Provision of analgesia to manage pain.

  • Induction of amnesia concerning perioperative events.

  • Anti-sialagogue effect to decrease saliva production.

  • Reduction of acidity and volume of stomach contents.

  • Prevention of postoperative nausea and vomiting.

  • Vagolytic actions to counteract certain reflex responses.

  • Facilitation of anaesthetic induction.

  • Prophylaxis against allergic reactions.

IDEAL PROPERTIES OF PREMEDICATION AGENTS

  • Safety: Drugs must be non-harmful if used appropriately.

  • Ease of Use: Should be straightforward to administer.

  • Efficacy: Effectively reduces apprehension and provides sedation.

  • Analgesic Properties: Should manage pain effectively.

  • Amnesic Properties: Ideally prevent memory of the event if desired.

  • Nausea Prevention: Should prevent both preoperative and postoperative nausea/vomiting.

  • Restlessness Reduction: Should calm the patient before procedures.

  • Suppression of Reflexes: Should inhibit undesirable reflex actions and secretions.

  • Facilitates Induction of Anaesthesia: Should assist in the smooth transition to anaesthesia.

ROUTE OF ADMINISTRATION AND DRUGS USED FOR PREMEDICATION

Administration Routes:

  • Oral: Common route, especially for children.

    • Example Agents: Diazepam, Promethazine.

    • Advantages: Easy, safe, economical, and convenient; does not need trained personnel.

    • Disadvantages: Requires patient compliance, long onset time, erratic absorption, lack of titration control, and potential for prolonged effects.

  • Rectal: Valuable for sedating young patients who may refuse oral medication.

    • Example Agents: Midazolam, Ketamine.

  • Intranasal: Rapid absorption bypassing hepatic metabolism.

    • Example Agents: Midazolam, Ketamine, Fentanyl.

  • Sublingual: Similar to intranasal, avoids first-pass metabolism.

  • Intramuscular: Rapid absorption and reliable maximum effect within 30 minutes.

    • Example Agents: Atropine, Ketamine.

    • Disadvantages: Requires trained personnel, risks related to needle use.

SEDATION TECHNIQUES

  • Definition: Sedation involves the reduction of irritability or agitation through the use of sedative drugs, administered to facilitate treatment or diagnostic procedures.

Conscious Sedation:

  • Defined as a state achieved by intravenous administration of a mixture of anxiolytics, sedatives, hypnotics, and/or analgesics.

  • Characteristics: The patient remains relaxed, able to communicate, maintain their airway, and ventilate adequately.

  • Routes: Administered via IV or inhalational methods.

INTRAVENOUS SEDATION

Drugs Used:

  1. Sedative, Hypnotics and Antianxiety Drugs:

    • Benzodiazepines: Diazepam, Midazolam.

    • Barbiturates: Methohexitone.

  2. Non-barbiturate hypnotics:

    • Propofol, Ketamine.

  3. Antihistamines:

    • Promethazine.

  4. Narcotic Agonists:

    • Pethidine, Pentazocine, Fentanyl.

Advantages:

  • Highly effective.

  • Rapid onset of action.

  • Capability for titration.

  • Safety provided by accessing the patient's vein.

  • Control over saliva secretions.

  • Minimized nausea and vomiting.

  • Diminished gag reflex and motor disturbances (especially relevant for patients with conditions like epilepsy and cerebral palsy).

Disadvantages:

  • Need for venepuncture.

  • Intensive monitoring required.

  • Potential for delayed recovery.

  • Patients require an escort post-procedure.

INHALATIONAL SEDATION (RELATIVE ANALGESIA)

  • Combines Nitrous Oxide and Oxygen to achieve sedation, particularly in children.

Indications:

  • Uncooperative children.

  • Mildly apprehensive adult patients.

  • Medically compromised patients.

  • Patients with pronounced gag reflex or specific cardiovascular conditions.

  • Epilepsy and hepatic dysfunction.

Contraindications:

  • Chronic obstructive pulmonary diseases, psychiatric disorders, early pregnancy.

GENERAL ANAESTHESIA

  • Definition: General anaesthesia is a controlled state of unconsciousness that includes partial or complete loss of protective reflexes, in which the patient cannot maintain their airway independently nor respond purposefully to verbal commands.

Indications in Dentistry:

  • Young children needing multiple extractions or extensive conservative dental work.

  • Uncooperative patients, particularly those with mental disabilities or physical limitations (e.g., cerebral palsy).

  • Allergic reactions to local anaesthetic solutions.

  • Failure of sedation or local anaesthesia.

  • Surgical extractions.

  • Major oral and maxillofacial surgical procedures.

GENERAL ANAESTHETIC TECHNIQUES

  • Administration of Gas: This requires specialized equipment, trained personnel, and involves various devices such as anaesthetic machines, laryngoscopes, Magill forceps, endotracheal tubes, pharyngeal airways, masks, pulse oximeters, and capnographs.

Techniques of Administration:

  • Inhalational Anaesthesia: Utilizes gases such as Nitrous Oxide, Halothane, Isoflurane, and Enflurane.

  • Intravenous Anaesthesia: Uses agents like Ketamine and Propofol.

  • Combination Anaesthesia: A mixture of both intravenous and inhalational approaches.

  • Endotracheal Anaesthesia: Involves intubating either nasotracheal (via the nose) or orotracheal (via the mouth), often requiring muscle relaxants like suxamethonium or pancuronium.

COMPLICATIONS OF GENERAL ANAESTHESIA

  • Classification of Complications:

  1. IV Anaesthesia Complications:

    • Hematoma, venous thrombosis, intra-arterial injection, etc.

  2. Endotracheal Intubation Complications:

    • Trauma to teeth and oral soft tissues, bleeding, aspiration of gastric contents, etc.

  3. Cardiovascular Complications:

    • Hypotension, syncope, cardiac arrest, arrhythmias.

  4. Respiratory Complications:

    • Respiratory depression, respiratory obstruction.

  5. Aspiration of Foreign Bodies:

    • Into the trachea-bronchial tract.

  6. Neurological Complications:

    • Delayed recovery, convulsions.

  7. Allergic Reactions.