Overview General anesthesia is a reversible state of central nervous system (CNS)depression, causing loss of response to and perception of stimuli. For patients undergoing surgical or medical procedures, anesthesia provides five important benefits:• Sedation and reduced anxiety• Lack of awareness and amnesia• Skeletal muscle relaxation• Suppression of undesirable reflexes• AnalgesiaBecause no single agent provides all desirable properties, several categories of drugs are combined to produce optimal anesthesia
Pre-anaesthetic medications Preanestheticmedications serve to–calm the patient, relieve pain, –protect against undesirable effects of the subsequently administered anesthetics or the surgical procedure.–facilitate smooth induction of anesthesia, –lowered the required dose of anestheticPreanestheticMedicine: •Benzodiazepines; midazolam or diazepam: Anxiolysis & amnesia.•barbiturates; pentobarbital: sedation•Diphenhydramine: Prevention of allergic reactions: •Antihistamines: H2 receptor blocker-famotidine, ranitidine: Reduce gastric acidity.
Pre-anaesthetic medications •Antiemetics- ondansetron: Prevents aspiration of stomach contents and post surgical vomiting:•acetaminophen, celecoxib or opioids (fentanyl) for analgesia •Anticholinergics: (glycopyrrolate, scopolamine):–Amnesia–Reduce bronchial and salivary secretion: –Reduce any tendency to bronchospasm–Prevent bradycardia and hypotension:
PATIENT FACTORS IN SELECTION OF ANESTHESIA•Drugs are chosen to provide safe and efficientanesthesia based on the type of procedure andpatientcharacteristicssuchasorganfunction,medical conditions, and concurrent medications.•Statusof organ systems•Cardiovascular system: •Respiratory system:•Liver and kidney•Nervous system•Pregnancy
Stages and depth of anesthesia/ STAGE 1- INDUCTION –Extends from the administration of anesthesia tothe time of loss of consciousness.–Pain is progressively abolished during this stage.–Patient remains conscious, can hear and see, andfeels a dream like state.