General Anesthesia Overview

Anesthesia and Analgesia

• Remifentanil is used for analgesia and enhancement of anesthesia during maintenance of anesthesia, and undergoes rapid metabolism by plasma esterases, with a short duration of action independent of dose and duration of infusion.

Ketamine

• Ketamine is used for induction and maintenance of anesthesia for short procedures, with doses ranging from 6.5-13 mg/kg for intravenous injection and 1-5 mg/kg for intramuscular injection.
• Contraindications include acute porphyrias, eclampsia, head trauma, hypertension, pre-eclampsia, raised intracranial pressure, severe cardiac disease, and stroke.
• Individual interactions with ketamine can lead to various side effects.

Remimazolam

• Remimazolam is used for anesthesia and analgesia, and should only be administered by experienced personnel with adequate training in anesthesia and airway management.
• Cardiac disease can cause side effects such as arrhythmias, dyspnea, gas exchange abnormal, respiratory disorders, vomiting, chills, feeling cold, and hiccups.

Dexmedetomidine

• Dexmedetomidine is used for maintaining sedation during intensive care, with an adult dose of 0.7 micrograms/kg/hour, adjusted according to response.
• It should only be administered by experienced personnel with adequate training in anesthesia and airway management.

General Anesthesia

• General anesthesia involves the use of various drugs to induce and maintain anesthesia during surgery.
• These drugs can be volatile, intravenously administered, or inhaled, and are maintained with an anesthetic.
• Short-acting opioids are also used as analgesics.

Intravenous Anesthetics

• Intravenous anesthetics are used to induce or maintain anesthesia during surgery, with most producing their effect in one arm-brain circulation time.
• Care is required in mouth, pharynx, or larynx surgeries where maintaining the airway may be difficult.

Volatile Liquid Anesthetics

• Volatile liquid anesthetics are used for induction and maintenance of anesthesia, and following induction with an intravenous anaesthetic.
• Examples include isoflurane, desflurane, and sevoflurane, each with different characteristics and side effects.

Malignant Hyperthermia

• Malignant hyperthermia is a rare but potentially lethal anesthesia complication characterized by rapid temperature rise, muscle rigidity, tachycardia, and acidosis.
• Patients at high risk should avoid volatile anaesthetics and suxamethonium chloride during anesthesia.

Medications and Surgery

• The risk of losing disease control when stopping long-term medication before surgery is often greater than the risk posed by continuing it during surgery.
• Anesthetists must be aware of all patients' medications, including corticosteroids, antiepileptics, antiparkinsonian drugs, antipsychotics, anxiolytics, bronchodilators, cardiovascular drugs, glaucoma drugs, immunosuppressants, and thyroid or antithyroid drugs.

Neuromuscular Blocking Drugs

• Neuromuscular blocking drugs are used for surgery and intubation, with examples including suxamethonium chloride, atracurium besilate, and cisatracurium.
• These drugs can cause various side effects, including arrhythmias, bradycardia, flushing, muscle contractions, and allergic cross-reactivity.

Antimuscarinic Drugs

• Antimuscarinic drugs are used as premedicants to reduce bronchial and salivary secretions, which can be increased by intubation, upper airway surgery, or inhalational anaesthetics.
• Examples include atropine sulfate, hyoscine hydrobromide, and glycopyrronium bromide.

Benzodiazepines

• Benzodiazepines are commonly used for premedication, providing relief of anxiety, sedation, and amnesia.
• Examples include diazepam and flumazenil.

Sedative Alpha2-Adrenergic Agonists

• Sedative alpha2-adrenergic agonists are used for intensive care patients, with examples including dexmedetomidine and clonidine hydrochloride.### Esketamine
• Blocks N-methyl-D-aspartate (NMDA) receptors, resulting in dissociative anesthesia and analgesia
• Used for induction and maintenance of anesthesia, analgesia in emergency medicine, and inhalation
• Should be administered by experienced personnel with adequate training in anesthesia and airway management
• Patients should be assessed for the risk of drug abuse prior to starting treatment and monitored for signs of this during therapy

Side Effects of Esketamine

• General side effects: anxiety, dizziness, nausea, vomiting
• Specific side effects: drowsiness, dry mouth, dysarthria, feeling abnormal, hallucinations, headache, hyperacusia, hyperhidrosis, hypertension, mood altered, nasal complaints, oral disorders, perception altered, psychiatric disorders, sensation abnormal, tachycardia, taste altered, tinnitus, tremor, urinary disorders, vertigo, vision blurred
• Rare or very rare side effects: muscle tone increased, nystagmus, skin reactions, hypotension, cystitis, disorientation, drug-induced liver injury, dysphoria, hallucination

Pregnancy and Breastfeeding with Esketamine

• Pregnancy: use only if potential benefit outweighs risk, may depress neonatal respiration if used during delivery
• Breastfeeding: use with caution for Major Depressive Disorder

Administration and Monitoring of Esketamine

• Solution can be diluted with glucose 5% or sodium chloride 0.9% for intramuscular or intravenous use
• A single-use device is required for intranasal use
• Patients should be informed not to eat for at least 2 hours before treatment and not to drink liquids for at least 30 minutes before treatment
• Monitor blood pressure at baseline and approximately 40 minutes after treatment
• Monitor for urinary tract and bladder symptoms during treatment

Alfentanil and Remifentanil

• Alfentanil: used for short procedures, with indications and doses for spontaneous respiration, assisted ventilation, intravenous injection
• Remifentanil: used for analgesia and enhancement of anesthesia at induction, with doses ranging from 0.25-1 microgram/kg for adults

Mivacurium and Pancuronium Bromide

• Mivacurium: short-term medication used during surgery and intubation, initially administered by intravenous injection
• Pancuronium Bromide: long-term neuromuscular blocking drug used for long duration during surgery and intubation, with an initial dose of 100 micrograms/kg

Rocuronium Bromide

• Used during surgery and intubation, with an initial dose of 600 micrograms/kg for adults and 20-30 micrograms/kg for intravenous injections
• Side effects: common procedural complications, rare or very rare angioedema, face oedema, and paralysis

Anticholinesterases and Sugammadex

• Anticholinesterases: reverse nondepolarising neuromuscular blocking drugs like pancuronium bromide
• Sugammadex: used for rapid reversal of neuromuscular blockade induced by rocuronium bromide or vecuronium bromide, primarily used in emergency situations

Postoperative Pain Management

• Patients should be discussed postoperative pain management options, considering clinical features, type of surgery, pain history, preferences, expected impact, treatment benefits and risks, and discharge plan
• A multimodal approach using different analgesics should be offered, and pre-emptive analgesia should be prescribed to manage pain after local anesthesia wears off

Intra-operative Analgesia

• Opioid analgesics such as alfentanil, fentanyl, and remifentanil can be used, which act within 1-2 minutes and have short durations of action
• Repeated intra-operative doses should be given with care as respiratory depression can persist postoperatively

Propofol and Other Anesthetics

• Propofol: used for anesthesia in surgical and diagnostic procedures, with dose depending on patient's age and condition
• Propofol infusion syndrome can result from prolonged infusion of propofol doses exceeding 4mg/kg/hour
• Desflurane: used for inducing anesthesia in adults, maintaining anesthesia in nitrous oxide-oxygen, and maintaining anesthesia in oxygen or oxygen-enriched air