Lecture 2_ IV Anesthesia.pdf

Intravenous anesthesia 1 a  Anesthesia 26 8 2024 my The state of general www.t anesthesia is a...

Intravenous anesthesia 1 a  Anesthesia 26 8 2024 my The state of general www.t anesthesia is a drug induced absence of perception of all sensations. mom Depths of anesthesia appropriate for surgical procedures can be achieved with a wide variety of drugs. General anesthetics are administered primarily by inhalation and intravenous (IV) injection.  MINI I With trim i.ws Him Igniting morphine Barbiturates HTNiwd.int Barbiturates for adults fused At one time, nearly every general anesthetic in adults was induced with a barbiturate. These agents were also widely used for control of seizures, anxiolysis, and procedural sedation and as sleep- inducing agents. They are now much less widely used in anesthesia.  Barbiturates Their primary mechanism of action is through binding to the γaminobutyric acid type A (GABA-A) receptor. Barbiturates increasing the duration of openings of a chloride-specific ion channel. III If  Propofol onset 15 30 sec Barbiturates onset action 30 60sec ex 1min wifi.ws osI Thiopental has a great lipid solubility and high nonionized fraction (60%) account for rapid brain uptake (within 30 s). If the central compartment is contracted (eg, hypovolemic shock), if the serum albumin is low (eg, severe liver disease or malnutrition), or if the nonionized fraction is increased (eg, acidosis), larger brain and heart concentrations will be achieved for a given dose with greater reduction of blood pressure. g  Barbiturates Respiratory Barbiturates depress the medullary ventilatory center, decreasing the H 0 ventilator response to hypercapnia and hypoxia. Apnea often follows an induction dose. Cardiovascular Decrease in blood pressure and an increase in heart rate. Central nervous system Barbiturates constrict the cerebral vasculature, causing a decrease in cerebral blood flow, cerebral blood volume, and intracranial pressure. Metabolism  Barbiturates A what class is Thiopental 0 0 D seizure EFFI intramuscular.gs  THE midazolam WAKI 611T 65 054 Had antagonist of Benzodiazepines Benzodiazepines reduce cerebral oxygen -b consumption, cerebral blood flow, and intracranial pressure but not to the extent the barbiturates do. Benzodiazepines Benzodiazepine binding to the GABA-A receptor increases the frequency of openings of the associated chloride ion channel. Benzodiazepine-receptor binding by an agonist facilitates binding of GABA to its receptor. Diazepam central muscle relaxant anticonvulaspt  Propofol onset action 15 30 last 5 10min milkywhitecolor Mechanism of action ff.IE CNS IF GABAA mimetics  Cl entry  suppression CNS medsdid't ride Pharmacodynamics & Pharmacokinetics few intravenous anaesthetics have the potential for drug addiction. ib bJ Adverse effects Propofol: hypotension (myocardial depressants), respiratory suppression. 2 derision A history of egg allergy does not necessarily contraindicate the use of propofol because most egg allergies involve a reaction to egg white meets (egg albumin), whereas egg lecithin is extracted from egg yolk. Thiopentane sodium have anticonvulsantaction also reduce intracranial tension increase vasodilate so hypotension  Propofol Cardiovascular sucinny choline The major cardiovascular effect of propofol is a decrease in arterial cause musclein blood pressure due to a drop in systemic vascular resistance (inhibition of sympathetic vasoconstrictor activity), preload, and cardiac contractility. which.netetic i MmYd9ontiYitc Respiratory Propofol is a profound respiratory depressant that usually causes apnea following an induction dose. Cerebral Propofol decreases cerebral blood flow, cerebral blood volume, and intracranial pressure. Propofol has anticonvulsant properties  Mdd Fospropofol Fospropofol is a water-soluble prodrug that is metabolized in vivo to propofol, phosphate, and formaldehyde. studies showing that it produces more complete amnesia and better Benzo conscious sedation for endoscopy than midazolam plus fentanyl. opoid propofol www.W It has a slower onset and slower recovery than propofol,  Etomidate Mechanism of action GABAA mimetics  Cl entry  suppression CNS www.XWA Therapeutic uses: -Etomidate: induction of anesthesia in patient at risk of hypotension or heart diseases. e (stable with cardiac patient used in heart surgery, not cause hypotension). Adverse effects 6.11 – High incident of pain at the injection site – High incidence of neausa and vomiting postoperatively – produce consistent adrenocortical suppression  Etomidate cause Vitamin Cdifficency Cardiovascular Etomidate has no effects on sympathetic tone or myocardial function. Myocardial contractility and cardiac output are usually unchanged. Respiratory Bronchodilator Ventilation is affected less with etomidate than with barbiturates or benzodiazepines. Even induction doses usually do not result in apnea unless opioids have also been administered. Cerebral Etomidate decreases cerebral metabolic rate, cerebral blood flow, and intracranial pressure.  Ketamine Mechanism of action NAMDA see inhibition Clinical uses – Produces significant analgesia. (Low-dose infusions of ketamine have been used for analgesia (“sub-anesthetic” doses) in postoperative). –enantiomer esketamine are now widely used to treat severe, treatment-resistant depression, WI Ketamine is used for intravenous induction of anesthesia, a particularly in settings where its tendency to produce sympathetic stimulation is useful (hypovolemia, trauma). Ketamine can be combined with other agents (eg, propofol or midazolam) in small bolus doses or infusions for conscious sedation  Ketamine isoflurane halothane is bronchodilator Cardiovascular Ketamine can cause transient but significant increases in systemic blood pressure, heart rate, and cardiac output. Respiratory Dose 2ms kg Ventilatory drive is minimally affected by induction doses of ketamine, though combinations of ketamine with opioids may produce apnea. Racemic ketamine is a potent bronchodilator, making it a good induction agent for asthmatic patients Cerebral nation adian caff ketamine is that it increases cerebral oxygen consumption, cerebral blood flow, and intracranial pressure.  Adverse effects -cardiovascular stimulation. -dissociative anesthesia most common Pre anesthetic medicine Benzodiazepine e Lorazepam  Dexmedetomidine Mechanism of action α2 -adrenergic agonist Clinical uses – It can be used for anxiolysis, sedation, and analgesia. –anesthesiologists have used it in combination with other agents to produce anesthesia. --It has also been used in combination with local anesthetics to prolong regional blocks. - ICU sedation -as a supplement to general anesthesia to reduce the need for -intraoperative opioids or to reduce the likelihood of emergence delirium after an inhalation anesthetic. It has also been used to treat alcohol withdrawal and the cocaine intoxication.  Dexmedetomidine Cardiovascular a loading dose of dexmedetomidine produces a small, transient increase in blood pressure accompanied by reflex bradycardia. Respiratory Dexmedetomidine produces no respiratory depression, making it nearly ideal for sedation of patients being weaned from mechanical ventilation. Cerebral Dexmedetomidine produces dose-dependent sedation. 4 606.1  Drug Interactions Dexmedetomidine may cause exaggerated bradycardia in patients receiving beta-blockers, so it should be dosed carefully in such patients. tachycardia in I II Catenolol inderalPropranolol  89 HR two P rate A