Anesthetics.pptx

Anesthetics Done by: Dr. Rawan Al-gharaibeh  Anesthesia: The state of reduced neurologic function Anesthetics are drugs that cause complete or partial loss of sensation Moderate Sedation:  It also called conscious sedation, and procedural sedation.  It’s anesthesia that does...

Anesthetics Done by: Dr. Rawan Al-gharaibeh  Anesthesia: The state of reduced neurologic function Anesthetics are drugs that cause complete or partial loss of sensation Moderate Sedation:  It also called conscious sedation, and procedural sedation.  It’s anesthesia that does not necessarily cause complete loss of consciousness and does not normally cause respiratory arrest.  This technique uses combination of several drugs from different groups.  Drugs may be given by IV, IM, spinal or oral routes.  The net effect is a type of anesthesia that allows the patient to relax, yet still maintain his or her own open airway, as well as respond to verbal commands. Used for diagnostic procedures and minor surgical procedures that do not require deep anesthesia  General anesthesia Anesthesia Local anesthesia General anesthesia normally involves:  complete loss of consciousness  loss of body reflexes elimination of pain and other sensations throughout the entire body skeletal and smooth muscle paralysis, including paralysis of respiratory muscles.  General anesthetics:  are drugs that induce general anesthesia  are most commonly used to induce anesthesia during surgical procedures.  is achieved by the use of one or more drugs.  Often a synergistic combination of drugs is used, which allows for smaller doses of each drug and better control of the patient’s anesthetized state.  Inhalational anesthetics: are volatile liquids or gases that are vaporized or mixed with oxygen to induce anesthesia.  Parenteral anesthetics usually given IV and are used for induction and/or maintenance of general anesthesia, induction of amnesia, and as adjuncts to inhalation anesthetic.  adjunct anesthetics “helper drugs” Their use complements the use of any other drug(s) and are used simultaneously with general anesthetics for:  anesthesia induction Sedation reduction of anxiety amnesia. Balanced anesthesia: The simultaneous use of both general anesthetics and adjunct drugs  Adjuncts:  Neuromuscular blocking agents.  Sedative hypnotics or anxiolytics.  Propofol, benzodiazepines, barbiturates, hydroxyzine and promethazine.  Opioid analgesics.  Anticholinergics (atropine).  Antiemetics (ondansetron). Mechanism of action and drug effects: The drugs vary widely in their chemical structures, and their mechanism of action is not easily explained by a structure-receptor relationship. Fat-soluble drugs are stronger anesthetics than water-soluble drugs.  The overall effect of general anesthetics is a progressive reduction of sensory and motor CNS functions. The degree and speed of this process varies with the anesthetics and adjuncts used along with their dosages and routes of administration. General anesthesia initially produces a loss of the senses of sight, touch, taste, smell, and hearing, along with loss of consciousness. Cardiac and pulmonary functions are usually the last to be interrupted; these are the classical “stages” of anesthesia. Adverse Effects: Sites primarily affected Heart (Myocardial depression is commonly seen) peripheral circulation Liver Kidneys respiratory tract  Malignant hyperthermia is an uncommon, but potentially fatal. – Occurs during or after general anesthesia or use of the NMBC succinylcholine – Sudden elevation in body temperature (greater than 104° F) – Tachypnea, tachycardia, muscle rigidity – Life-threatening emergency – Treated with dantrolene (skeletal muscle relaxant)  The dose of any anesthetic depends on:  the complexity of the surgical procedure  the physical characteristics of the patient. With regard to pharmacokinetics:  all of the general anesthetics have a rapid onset of action along with rapid elimination upon discontinuation. Anesthesia is maintained intraoperatively by continuous administration of the drug. 1. Isoflurane:  Is fluorinated ether that is a chemical isomer of the older fluorinated ether enflurane.  It has a more rapid onset of action, causes less cardiovascular depression, and has a little or no associated toxicity. 2. Sevoflurane:  Is the newest fluorinated ether and is now widely used.  it has rapid onset and rapid elimination, make it especially useful in outpatient surgery settings.  It is also nonirritating to the airway, which greatly facilitates induction of an unconscious state, especially in pediatric patients. 3. Ketamine:  Given IV, it can be used for both general anesthesia and moderate sedation.  This drug is highly lipid soluble and penetrates the BBB rapidly, which results in a rapid onset of action.  It has a low incidence of reduction of cardiovascular, respiratory, and bowel function.  Adverse effects include hallucinations. 4. Propofol (Diprivan):  It is a parentral general anesthetic  used for the induction and maintenance of general anesthesia and also for sedation for mechanical ventilation in ICU settings.  In lower doses it can be used as a sedative- hypnotic for moderate sedation.  It is also typically well tolerated, producing few undesirable effects. Local anesthesia (regional anesthetics ) They reduce pain sensations at the level of peripheral nerves. They do this by interfering with nerve transmission in specific areas of the body, blocking nerve conduction only in the area in which they are applied without causing loss of consciousness. They are most commonly used in clinical settings in which loss of consciousness is undesirable or unnecessary. These include childbirth, dental procedures, and diagnostic procedures.  Types of local anesthesia: 1-Central: Spinal or intraspinal anesthesia: Anesthesia drugs are injected into the area near the spinal cord within the vertebral column. Intraspinal anesthesia is commonly accomplished by: 1. Intrathecal anesthesia: involves injection of anesthesia into the subarachnoid space. 2. Epidural anesthesia: involves injection of anesthesia via a small catheter into the epidural space without puncturing the dura. 2-Peripheral: Infilteration: small amounts of anesthetic solution are injected into the tissue that surrounds the operative site. Nerve block: anesthetic solution is injected at the site where the nerve innervates a specific are such as a tissue. Topical anesthesia: the anesthetic drug is applied directly onto the surface of the skin, eye, or any mucous membrane to relieve pain or prevent it from being sensed. Mechanism of action and drug effects:  Local anesthetics work by rendering a specific portion of the body insensitive to pain by interfering with nerve transmission in that area.  They block the generation and conduction of impulses through all types of nerve fibers by blocking the movement of certain ions important to this process. Adverse effects  Possible systemic effects of the administration of local anesthetics include effects on circulatory and respiratory function.  The systemic adverse effects depend on where and how the drug is administered.  Such adverse effects are somewhat unlikely unless large quantities of a drug Lidocaine: is one of the most commonly used local anesthetics. It is available in several strengths, both alone and in different concentrations with epinephrine, and is used for both infiltration and nerve block anesthesia. Lidocaine is also available in topical form. Parenteral lidocaine is also used to treat certain cardiac dysrhythmias. Neuromuascular blocking drugs (NMBDs): These drugs prevent nerve transmission in skeletal and smooth muscles, leading to paralysis. They are often used as adjuncts with general anesthetics. NMBDs also paralyze respiratory muscles, so mechanical ventilation is required to prevent brain damage or death by suffocation. Mechanism of action: They are classified into two groups based on mechanism of action: 1. depolarizing: they work similarly to the neurotransmitter acetylcholine, they are competitive agonists. 2. Nondepolarizing also bind to acetylcholine receptors at neuromuscular receptors at neuromuscular junction, and they block the usual action of acetylcholine, therefore these drugs are competitive antagonists of acetylcholine  Depolarizing: succinylcholine. Nondepolarizing:  Short acting: mivacurium.  Intermerdiate-acting drugs: atracurium, rocuronium and vecuronium.  Long-acting drugs: dexacurium, pancuronium and tubocurarine. Indications:  Main use: maintaining controlled ventilation during surgical procedures  Endotracheal intubation (short-acting)  To reduce muscle contraction in an area that needs surgery  Diagnostic drugs for myasthenia gravis Adverse effects (Few when used appropriately) May cause: Hypotension (blockade of autonomic ganglia) Tachycardia (blockade of muscarinic receptors) Hypotension (release of histamine) Succinylcholine: It is metabolized more slowly than Ach. Because of this slower metabolism, repolarizing cannot occur. As long as sufficient concentrations are present, the muscles lose its ability to contract, and flaccid muscle paralysis results. Because of its quick onset of action (less than 1 min), succinylcholine is most commonly used to facilitate endotracheal intubation. Pancuronium: Is a long-acting nondepolarizing NMBD. Its most commonly employed for long surgical procedures that require prolonged muscle paralysis. It’s used as an adjunct to general anesthesia to:  facilitate endotracheal intubation  to provide skeletal muscle relaxation during surgery or mechanical ventilation. Vancuronium: It is an intermediate-acting nondepolarizing NMBD. Long-term used in the ICU setting has resulted in prolonged paralysis and subsequent difficulty in weaning. It is used as an adjunct to general anesthesia to:  facilitate tracheal intubation  to provide skeletal muscle relaxation during surgery or mechanical ventilation Nursing implications: Always assess past history of surgeries and response to anesthesia Assessment is vital during preoperative, intraoperative, and postoperative phases Vital signs Baseline lab work, ECG Oxygen saturation ABCs (airway, breathing, circulation) Monitor all body systems  Watch for sudden elevations in body temperature7 During recovery, monitor for cardiovascular depression, respiratory depression, and complications of anesthesia Implement safety measures during recovery, especially if motor or sensory loss occurs because of local anesthesia Reorient patient to his or her surroundings Teach the patient about postoperative turning, coughing, deep breathing