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1、ANESTHESIA:OVERVIEW,Anesthesia is the use of medications and close monitoring to provide comfort and maintain vital life functions during surgery or other medical procedures.,Anesthesia is concerned not only with the administration of anesthesia for surgery but also with many other areas of patient
2、care, including critical care medicine, management of chronic pain,and respiratory therapy.,Anesthesia: reversible, drug-induced loss of sensation in the entire body or in a part of it Local anesthetic agents: agents that block sensory and motor nerve conduction to produce temporary loss of sensatio
3、n without a loss of consciousness General anesthetics: CNS depressants with action that can be induced and terminated more rapidly than sedative hypnotics Preanesthetic medication: may include sedatives, opioids, tranquilizers and anticholinergic agents,What determines the type of anesthesia used?,Y
4、our medical history. The results of your physical exam. This is done to evaluate your current health and identify any potential risks or complications that may affect your anesthesia care. The results of tests such as blood tests or an electrocardiogram The reason for your surgery and the type of su
5、rgery. .,Physical status classification of the American society of Anestheriologist,Anesthesia is divided into four basic categories: general anesthesia regional anesthesia local anesthesia sedation,Today we just learn General anesthesia,There are several drugs and gases that can be combined or used
6、 alone to produce general anesthesia. When anesthetics reach the bloodstream, the drugs that affect the brain pass through other blood vessels and organs so they are often affected too. Therefore, patients must be carefully monitored.,General anesthesia is used for more extensive procedures or for p
7、rocedures that arent amenable to regional anesthesia. The medications used in general anesthesia are given intravenously or by inhalation. The drugs circulate in your bloodstream to all areas of your body, including your brain. It results in amnesia, paralysis and analgesia.They can suppress all of
8、your protective reflexes, such as coughing, gagging and even breathing. Consequently, a general anesthetic requires the use of a mask or breathing tube during the surgery.,Inhaled General Anesthetics,Nitrous oxide Halothane Enflurane Isoflurane Sevoflurane Desflurane Xenon (rarely used),Anesthesia M
9、achine,IV General Anesthetics and Sedative Agents,Thiopental Methohexital Propofol Etomidate Ketamine Diazepam Midazolam Lorazepam,These drugs quickly reach the brain and their effect is dependent on several factors including the volume in which the drug is distributed in the body, the fat-solubilit
10、y of the drug, and how quickly the body eliminates the drug.,It is not completely clear exactly how general anesthetics work at a cellular level, but it is speculated that general anesthetics affect the spinal cord (resulting in immobility), the brain-stem reticular activating system (resulting in u
11、nconsciousness) and the cerebral cortex (seen as changes in electrical activity on an electroencephalogram).,Four stages of Anesthesia and increasing depth of CNS depression,1. Analgesia: awareness of pain without amnesia 2. Excitement: delirium and excited with amnesia 3. Surgical anesthesia: uncon
12、scious, no pain reflexes, regular respiration and BP maintained 4. Medullary depression: severe respiratory and CV depression; death without CV and respiratory support,Curved (Macintosh) 1. The tip of the blade is advance into the space between the base of the tongue and the pharyngeal surface of th
13、e epiglottis. 2. Move the blade forward and upward to elevate the epiglottis and expose the glottic opening. Straight (Jackson-Wisconsin) or Straight with curved tip (Miller) 1. The tip of the blade is passed beneath the laryngeal surface of the epiglottis 2. Same with curve blade,Anesthesia Monitor
14、s,monitoring of heart rate (ECG), oxygen saturation (pulse oximetry) blood pressure (NIBP & IBP arterial) inspired and expired gases (for oxygen, nitrous oxide, carbon dioxide, and volatile agents) monitoring of temperature central venous pressure cerebral activity (EEG) neuromuscular activity (peri
15、pheral nerve stimulation monitoring) urine output blood sugar levels buildup of exhaled inhalational anesthetics,MONITORS,Blood pressure monitoring NIBP using automated device; size of cuff should cover 2/3 of arm. Too wide cuff can produce false low BP while too small cuff can cause false high BP.
16、IBP via arterial line to determine real time BP ECG Lead II aids in recognition of changes in cardiac rhythm and Lead V aids in recognition of ischemia. It can also show changes that may suggest electrolyte imbalance. Pulse oximetry Reads oxygen saturation of blood via spectrophotometry. High levels
17、 of carbon monoxide can cause false high saturation values while color dyes on nails can cause false low saturation values. Capnography / End tidal carbon dioxide Carbon dioxide levels in blood reflects the dead space ventilation. Reading can also aid in verifying correct placement of the ET tube, p
18、resence of spontaneous respiration, presence of airway obstruction. Thermometer Prevention of hypothermia can improve anesthesia outcome. Probes for esophageal, rectal, bladder, skin & tympanic membrane are available.,An important property of anesthetics is reversibility. When the surgery is over, t
19、he anesthesiologist would shut off the anesthetic and have the patient wake up from the anesthetic-induced sleep. Once the anesthetic gas is turned off, the blood stream brings the gas back to the lungs where it is eliminated. The more soluble the gas is in blood, the longer it takes to eliminate. N
20、itrous oxide and desflurane are the shortest-acting anesthetic gases because they are the least soluble in blood.,Muscle Relaxants,Succinylcholine (Anectine) - depolarizing Vecuronium (Norcuron) non depolarizing intermediate acting Rocuronium (Esmeron) non depolarizing intermediate acting Pancuroniu
21、m (Pavulon) non depolarizing long acting Atracurium (Tracrium) - non depolarizing intermediate acting Pipecuronium Rapacuronium Mivacurium Cisatracurium Curare, the active ingredient of which is tubocurarine Metocurine Gallamine,Adverse effects of muscle relaxants,Succinylcholine may cause hyperkale
22、mia if given to burn patients, or paralysed (quadraplegic, paraplegic) patients. Succinylcholine may also trigger malignant hyperthermia in susceptible patients. Neuromuscular blockade can not be reversed,Opioids,Morphine Diamorphine, (diacetyl morphine, also known as heroin) Codeine, (methyl morphi
23、ne) Fentanyl (Sublimaze, Durogesic) Alfentanil Sufentanil Remifentanil Meperidine, also called pethidine (Demerol) Methadone Oxycodone (Oxycontin) Naloxone, chemically similar to some analgesics; not a painkiller and reverses the effects of morphine-like agents. Nalbuphine (Nubain) Butorphanol (Stad
24、ol),Side effects of Opioids,Analgesia Respiratory depression Ileus / delayed gastric motility Nausea & vomiting Hypotension Pruritus,What happens during recovery from anesthesia?,PACU / Recovery Room Drowsiness and Respiratory Depression Numbness & Residual muscle relaxant Hypothermia & Shivering Nausea & Vomiting Pain & Agitation Unstable vital signs and Hypotension,Tomorrow Begins Today! Thank you,