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Obat Anestesi/Ike Mega Irawati/ 091.0039/ S1-2A

GENERAL ANESTESI

Posted Selasa, 11 Januari 2011 by Ike Mega Irawati
INTRODUCTION  
Efforts are made to reduce or eliminate pain with drug use in surgical procedures have been performed since ancient times, including the provision of ethanol and opium (opiate) orally. The first scientific demonstration of the use of anesthesia for surgery performed by William Morton in Boston in 1846 by using diethyl ether. While the term anesthesia was first proposed by OW Holmes which means no pain. Anesthesia is done first by the Egyptians to use narcotics, the Chinese people use cannabis Indica, and beating the head with a wooden stick to remove consciousness. Anesthesia is divided into two groups: (1) general anesthesia and (2) local anesthesia. The following will be explained on general anesthesia and local anesthesia. 

Definition  

General anesthesia is missing pain accompanied loss of consciousness. Anesthesia used in surgery with the intention of achieving unconsciousness, hinder the stimulus of pain (analgesia), blocked the reflex response to surgical manipulation and creates pelemasan muscle (relaxation). General anesthesia are now available can not meet this goal as a whole, then in anesthesia for surgery is generally used in combination hipnotika, analgesics, and muscle relaksansia. 

Procedures on General Anesthesia 

General anesthesia can be given by inhalation or intravenous injection.
1. Inhalation anesthetics: halothane, enflurane, isofluran, sevoflurane, desflurane, and methoxyflurane is a volatile liquid. These drugs are given as vapor through the airways. The way of inhalation anesthetics: • Open the drop method: an anesthetic substance dripped on cotton placed under the noses of patients so that levels of a substance which is inhaled anesthetics is unknown and wasteful use as an anesthetic agent evaporates into the open air. • Semiopen drop method: in this manner nearly equal to open the drop, only to reduce the waste of anesthetic agents then used a mask. • Semiclosed method: given the same air that is inhaled oxygen levels can be determined. The advantage of this way is it an anesthetic can be adjusted by giving a certain degree of anesthetic agents and hypoxia can be avoided by giving O2. • Closed method: almost the same as semiclosed, only the expiratory air flow through the NaOH that can bind CO2, so that air containing the anesthetic can be used again. This method is more efficient, safer, and easier, but the price is quite expensive appliance. The types of first-generation inhaled anesthetics such as ether, cyclopropane, and chloroform are not used anymore in developed countries because of its flammable (such as ether and cyclopropane) and its toxicity to organs (chloroform). 
2. Intravenous Anesthesia. Some drugs are used intravenously (either alone or in combination with other drugs) to induce anesthesia, or as a component of balanced anesthesia (balanced anesthesia), or to soothe patients in emergency care units who require artificial breathing assistance for the long term.

Classification of General Anesthesia Drugs  

a. Inhalation Anesthesia Halothane, enflurane, isofluran, sevoflurane, desflurane, and methoxyflurane is a volatile liquid. 

Halothane 

 • Smell and taste do not sting,   
• Savor anestetisnya very strong but the efficacy and power analgetisnya mild muscle relaxation, the new adequate in anesthesia in  • halothane used in low doses and in combination with a relaksans bibs, like galamin or suksametonium.  • relatively low solubility in blood induction of slow, easy to use, does not stimulate the respiratory mucosa  • crushing, and laryngeal reflexes from Paring, bronkioli widen and reduce the secretion of saliva and secretions of the bronchi • Famakokinetik: partial dimetabolisasi inwardly bromide, inorganic chloride, and trifluoacetik acid. • Side effects: suppress breathing and heart activity, hypotension, if repeated use, it can cause liver damage. • Dose: 0.5 to 3 tracheal v%. Enflurane • strong inhalation anesthetics are used in various types of surgery, as well as analgetikum in childbirth. • Has the power and muscle relaxation analgetis good, relaxes uterine muscle • Not so pressing SSP • Resorpsinya after inhalation, rapid induction time of 2-3 minutes • Most is excreted through the lungs in one piece, and the rest is converted into free fluoride ion • Side effects: hypotension, respiratory pressure, aritmi, and stimulate the CNS. Post-surgery may arise hipotermi (shivering), and nausea and vomiting, can increase bleeding during childbirth, SC, and abortion.
Isofluran (Forane) • The smell bad • Includes a strong inhalation anesthesia with muscle relaxation properties and good analgetis • Power of work and its emphasis thdp SSP = enflurane • Side effects: hypotension, aritmi, chills, constriction bronkhi, increasing the number of leukocytes. Can arise after surgery nausea, vomiting, and the tense situation • Dosage: 3 to 3.5% Dlm isofluran O2; + NO2-O2 = induction; maintenance: 0.5% -3%
 

b. Gas anesthesia 
1. Potential minor  
2. Difficult to dissolve in the blood  
3. N2O • achromatic gas, odorless, LBH BRT air dp, dg combined O2 • weak anesthetic potency, rapid induction • good analgesic effect (20% N2O) • the use of old: nausea, vomiting, slow build Included in this group adalh siklopropan. Siklopropan • Anesthesia gas is strong, specific smell, no color • More heavy than air and kept in the form of pressurized fluid. • Highly flammable and explosive, therefore, anesthetic gases used only in the closed method.
 

c. Intravenous Anesthesia 
 Included in this group are: barbiturates (thiopental, methothexital), benzodiazepines (midazolam, diazepam), opioid analgesics (morphine, fentanyl, sufentanil, alfentanil, remifentanil), propofol, ketamine, a compound that can cause a state arylcylohexylamine dissociative anesthesia and medications Other (droperianol, etomidate, dexmedetomidine).
Barbiturates  

1. Stimulation system blockade in the formation retikularis  
2. Respiratory inhibition in the medulla oblongata  
3. Inhibition of muscle contraction. heart, cardiac sensitization caused ill against ketekolamin  
4. Dose of anesthesia: excitatory CNS; doses> = CNS depression  
5. Dose: induction = 2 mg / kg (iv) in the 60 sec; maintenance = half dose induction o Na tiopental: • Induction: TGT BB dose, physical condition and eds • DWS: 2-4ml of 2.5% scr lar intermittent performance every 30-60 sec ad o Ketamine • the nature of analgesic, anesthetic, brief work kataleptik dg • strong analgesic for somatic system, weak for visceral system • relaxation o. Plain striated (-), rising tone • increase BP, pulse, bulk jtg • Hallucinations (+) Fentanyl and droperidol • Analgesic & anesthetic neuroleptics • Combination of fixed • Safe naturally given pd yg px hiperpireksia ok other general anesthesia • Fentanyl: short working period, the early rapid crimes • Droperidol: working lives long & slow early labor Diazepam • A benzodiazepine with the ability to relieve anxiety, muscle relaxing effect that works in a central, and when given intravenously to work as antikejang. Drug response lasted for 12-24 hours a real gift in 30-90 min stlah SCRA 15 min slah oral and intravenous injection. • Contraindications: Hypersensitivity to benzodiazepines, parenteral administration is contraindicated in patients with shock or coma • Cause of sleep and impairment of consciousness accompanied nistagmus, talk slow • Analgesics (-) • Sedation basalt in regional anesthesia, endoscopy, dental procedures, anesthesia induction pd cardiovascular patients • effects of anesthesia <ok job at first slow, long recovery period • To premedication (neurolepanalgesia) & convulsions ok overcome local anesthesia • Dimetab mjd active metabolite • T ½> with age • ESO: stopping the breath, phlebitis and thrombosis (+) (route IV) • Dose: induction = 0.1 to 0.5 mg / kg
 

Stages of Anesthesia  
1. Stage 1 (analgesia)
• Patients experiencing analgesia,  
• The pain disappeared,  
• Awareness is reduced
2. Stage II (delirium / excitation)  

• The patient was restless and lost consciousness 
• Patients experiencing movement that is not according to the will (laugh, scream, cry, sing)  
• Volume and speed of irregular breathing 
• nausea and vomiting may occur 
• incontinence of urine and defecation often occurs  
• Midriasis, hypertension  
3. Stage III (anesthesia, surgery / operation)  
• Breathing becomes shallow, rapid, and orderly, as in a state of sleep (belly breathing)  
• Eye movements and eye reflex loss / movement was not at the discretion of the eyeball  
• Muscles become weak, for example, the head can be moved to the right and left freely, arms raised and then released to fall freely without being detained
4. Stage IV (paralysis of the medulla oblongata)  

• cardiac and respiratory activity spontaneously stopped.  
• There was severe depression of respiratory center in the medulla oblongata and vasomotor center. Without the help of a respirator and circulation, the patient will quickly die. So this stage as far as possible be avoided.
 

Working Mechanism  
a. Inhalation anesthesia
Inhaled anesthetics work pressure and evoke spontaneous neuronal activity in the brain areas. As an inhalation anesthetic gases and liquids used in flying, each very different in the speed of induction, activity, nature relaxes the muscles and relieve pain. To get the quickest response, this drug at the beginning should be given in high doses, which is then reduced to simply maintain a balance between giving and spending. Advantages compared with inhalation anesthesia intravenous anesthesia is likely to be able to more quickly change the depth of anesthesia by reducing the concentration of gas / vapor inhaled.
b. Intravenous Anesthesia

Intravenous medications such as thiopental, etomidate, and propofol have first anesthetist working faster compared to the most recent inhalation gas compound, such as desflurane and sevoflurane. The compound is commonly used for intravenous induction of anesthesia. The speed of recovery in most of the compounds intravenously is also very fast.

Pharmacokinetics  

The depth of anesthesia is determined by the concentration of anesthetic in the central nervous system. The speed at which an effective brain concentrations (speed induction of anesthesia) depends on how much influence the pharmacokinetics of uptake and spread of anesthesia. These factors determine the difference in transfer speed of inhalation anesthetics from the lungs to the blood and from blood to the brain and other tissues. These factors also affect the anesthesia recovery period after anesthesia was stopped. Influenced / tek partial anesthetic substance Dlm brain. Determinants of partial pressure: 
 1. Partial pressure of inspired anesthetic gas • To accelerate the induction: the inspired gas levels should be higher than the expected partial pressure in the network • Once reached, reduced to maintain anesthesia  
2. Pulmonary ventilation • Hyperventilation to hasten the entry of an anesthetic gas into the circulation and tissue • soluble substances in the blood: halothan  
3. The transfer of anesthetic gas into the flow drh dr alveoli • Membrane alveoli easily bypassed by the diffusion of anesthetic gas from the alveoli into the blood is flow 
4. Transfer of anesthetic gas from Dareh flow to tissue cells • Networks that have a rapid blood flow, the equilibrium partial pressure is more easily achieved so that the anesthetic gas is easier to move.
Pharmacodynamics

Inhaled anesthetics work pressure and evoke spontaneous neuronal activity in the brain areas. To get a reaction as soon as possible, these drugs at the beginning should be given in high doses. The compound is commonly used for intravenous induction of anesthesia. The speed of recovery in most of the compounds intravenously is also very fast.
Side effects  

Almost all inhaled anesthetics which resulted in a number of side effects and most importantly: 
 1. Suppress respiration in anesthesia in mainly caused by halothane, enflurane and isofluran. This effect is the lightest on N2O and ether. 
 2. Pressing the cardiovascular system, especially by halothane, enflurane and isofluran. This effect is also caused by the ether, but because the ether also stimulate the sympathetic nervous system, then the overall effect becomes lighter. 
 3. Damage the liver and kidneys, particularly chlorine compounds, such as chloroform. 
 4. Oliguric (reversible) due to reduced drainage of blood in the kidneys, so patients need to dihidratasi taste.  
5. Pressing temperature regulation system, which raised the feeling of chills (shivering) post-surgery.

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