ABSTRACT
This article reviews the literature and update the concepts of local anesthetic use in dentistry. Describe the pain pathways and the highlights in the pharmacology of local anesthetics are frequently used in dentistry. It describes the different types of available local anesthetics for dental use, the concentration of both the anesthetic and the vasoconstrictor agent, and the effects of each in the body.
Keywords: Anesthesia. Dentistry. Local anesthetics.
SUMMARY
To review the literature and to update the concepts about the use of dental local anesthetics, the present article describes the ways of pain and the most important aspects in the pharmacology of the more frequently used local anesthetics in dentistry. The different types of available local anesthetics for dental use are described, as well as the concentration including the vasoconstrictor action and their effects in the organism.
Key words: Anesthetics. Local anesthetics.
Colomb Med 2001 32: 121-124
The health professionals most frequently used local anesthetics are dentists. For this reason, it is worthwhile to recall and remember all the anatomical, pharmacological and techniques of local anesthesia in dentistry. This article aims to describe the pain pathways, nerve conduction and pharmacological aspects of conduction block.
Although the technique for application of the anesthetic is very important to know and use it correctly, this is not addressed, since it believes that its length and depth would result in another article on the subject. However, it is important to note that despite having very good technical skills, the clinician should not forget, much less minimize the theoretical basis of what is going to be reviewed below. In addition, the dentist must make a good clinical history to ascertain the general condition of the patient who is going to use local anesthetic drugs that might be taking and drug interactions.
WAYS OF PAIN
The site reached by the trigeminal sensory nerve fibers located in the brainstem and extends from the bridge to the top of the spinal segment, caudal sub nucleus be the end where myelinated and unmyelinated fibers. These afferent fibers are responsible for transmitting nerve impulses from different receptors that respond to noxious stimuli (nociceptors) to own central nervous system (CNS). Nociceptors are scattered throughout the human anatomy and through nerve fibers carry the momentum generated by painful sensations in the CNS. However, the reaction can be painful emotionally influenced by cultural factors, anxiety, previous experiences, among otras1.
It is important to be familiar with the anatomy of the trigeminal nerve or cranial nerve V and its three branches (most of which are sensory nerve fibers: ophthalmic and maxillary division and much of the mandible, which is mixed), because at this nerve passes the application of anesthetic to block sensation dolorosa2.
The cells (neurons) of the peripheral nerves are composed of a cell body (perikaryon) and an axon. The perikaryon is composed of a cell membrane (containing lipids and proteins), nucleus and cytoplasm. The axon is accompanied by supporting cells or Schwann and myelinated nerve fibers unmyelinated unlike consist of a single axon surrounded by Schwann cells, through the dissemination occurs axon of the nerve impulse. At rest the cell membrane is maintained with a negative electrical potential (K-) 1. If the membrane is excited, it generates an action potential and initiates the depolarization of her in a more or less slow during which the electrical potential within the cell becomes progressively less negative. After this phase ends and reverses the depolarization potential across the cell membrane and the interior becomes positively charged (Na +). After repolarization occurs until the cell becomes more negative again on the outside that is positive, and again achieved the resting potential.
BLOCKING OF NERVE CONDUCTION
Local anesthetics are drugs that reversibly block nerve impulse conduction, as it inhibits the excitation of the membrane of myelinated nerve fibers (A) and non-myelinated (C). Also slow down the process in the depolarization phase and reduce the inflow of sodium ions. That is, it reduces the permeability with respect to sodium (decreased rate of depolarization) thus the propagated action potential does not reach its threshold value and ultimately this determines a failure in nerve impulse conduction.
CLASSIFICATION OF LOCAL ANESTHETICS
Tables 1 and 2 describe the desirable properties of local anesthetics, the concentration and duration of action. In general local anesthetics used in dental procedures fall into two main groups: aminoésteres and aminoamidas1, 3.4.
Aminoésteres. They are para-aminobenzoic acid derivatives. The first local anesthetic used was cocaine in 1884 by Hall4, 5. In the group of stand aminoésteres procaine, cocaine, chloroprocaine and tetracaine.
Procaine. The synthesis of procaine (Novocain ®) will only be achieved until 1905 with the work of Einhron1, 3 and is the prototype of the local anesthetic properties but lacks topical anesthetic. Like many other anesthetics of the ester group is hydrolyzed to para-aminobenzoic acid (which inhibits the action of sulphonamides) and dimethylaminoethanol. The biotransformation is controlled by the enzyme pseudocholinesterase; therefore, its metabolism occurs in the blood. It is used in concentrations of 0.25% to 0.5% for infiltrative anesthesia, 0.5% to 2% to 10% blocks and epidural anesthesia. It can be used in combination with other drugs such as penicillin (penicillin G procaine) to prolong the pharmacological effect, allowing for slower absorption and causes of penicillin has demonstrable concentrations in blood and urine for extended periods. Procaine is now widely used in alternative medicine, although research dating back to 1925. One of the main uses in dentistry is the blockage of pain points in myofascial pain dysfunction syndrome (muscles of mastication). "Huneke neural therapy is a therapeutic system that exerts its action through the vegetative system with the application of either local anesthetic injected into the ground segmental disease, in this case segmental therapy, or to disconnect the interference field of illness "6.
Aminoamides. To this group belong anesthetics including lidocaine, prilocaine, mepivacaine, bupivacaine and etidocaine. These drugs are metabolized in the liver and not blood. The most commonly used in dentistry are lidocaine (Xylocaine ®) and prilocaine (Citanest ®, Pricanest ®). Lidocaine becomes monoetilglicinaxilidida and finally 4-hidroxixilidida. Lidocaine is absorbed in the urine.
Lidocaine. Lidocaine (Xylocaine ®), introduced in 1948 is one of the local anesthetic most commonly used because it produces more rapid anesthesia, intense, lasting and comprehensive peace that procaine and possesses very buenos1 topical effects, 5. It is the agent of choice in patients sensitive to esters. In addition to anesthetic is also used intravenously as an antiarrhythmic. It is available in liquid form for injection, jelly, cream, ointment and spray. In dentistry is available at Radiology of 1.8 ml of 2% with epinephrine 1:80,000, the maximum dose of lidocaine is 5 mg / kg, if used mg/kg5 vasoconstrictor is 7. To convert to milligrams percentage should be multiplied by 10. Therefore, a Radiology dental use has 1.8 ml x 2% x 10 = 36 mg of lidocaine. To express the concentration of epinephrine in micrograms are converted as follows:
This means that when one speaks of an epinephrine concentration of 1:80,000, is for each cubic foot (= 1 ml), 12.5 mg of epinephrine. The duration of action of lidocaine is approximately 2 hours and 4 times more potent than procaine. You can also get carpule lidocaine 2% without vasoconstrictor, and 2% with epinephrine 1:100,000. Also available in these concentrations in bottles of 50 ml. For topical spray is 10% and 2% jelly ointment 5%.
Prilocaine. The initiation and duration of their actions is a little longer than the lidocaína1. It takes approximately 2 hours and is 3 times more potent than procaine, has a toxic effect and is the exclusive secondary metahemoglobinemia7. In dentistry you can get in Radiology at concentrations of 2% and 3% (Citanest ®) octapresín (Felypressin ®) or 4% (Pricanest ®) without vasoconstrictor. It is used for infiltration anesthesia, regional block and cord.
Mepivacaine. Mepivacaine (Carbocaine ®) is an introduction of faster acting and longer duration than lidocaine; no topical properties. Its duration is approximately 2 hours and is twice as potent as procaine. It is used for infiltration anesthesia, blockade and spinal anesthesia. It is available in concentration of 3% without vasoconstrictor and 2% with epinephrine Neocobefrín (Levonordefrin ®) 1:20,000.
Bupivacaine. Bupivacaine (Marcaine ®) is four times more potent than lidocaine, its action is more delay, but it lasts about 6 horas5, 7. Bouloux et al.8 found that bupivacaine reduced pain in third molar surgery in the first 8 postoperative hours, compared with lidocaine. There was in that study, no difference in cardiac response or toxicity. There are several studies in the literature to compare the analgesic effects in postoperative joint surgery, intra-articular injection of bupivacaine alone, morphine alone and a combination of dos9-13. Furst at al.9 found that in post-operative arthroscopy of the temporomandibular joint bupivacaine alone provided a better analgesic effect. It is available in bottles with concentrations of 0.25% and 0.5% with or without epinephrine. The highest dose without epinephrine is 2.5 mg / kg and 4 mg/kg5 epinephrine. There are also carpule of 1.8 ml at concentrations of 0.5% with epinephrine 1:200,000. Maxillofacial surgeons use it a lot in orthognathic surgery, temporomandibular joint and trauma among others, for postoperative pain management for its long duration of action.
METABOLISM
The ester group local anesthetics are metabolized in the plasma by the enzyme pseudocholinesterase and a major metabolite is the para-aminobenzoic acid that appears to be responsible alérgicas1 reactions, 3. The amide anesthetics are metabolized in the liver and are not para-aminobenzoic acid. Local anesthetics are excreted in the urine.
PHARMACOLOGICAL ACTION OF LOCAL ANESTHETICS
It is important to consider the actions of local anesthetics on different body systems in order to assess adequately the phenomena of toxicity that might arise. Almost all dental procedures, including oral surgery, can be done under local anesthesia. When this is possible is preferable to do it this way general14 anesthesia. Studies Nkansah at al.15 found a mortality of 1.4 per 1'000, 000 2'830, 000 cases between 1973 and 1975 in Ontario (Canada).
Central nervous system. Produce central nervous system stimulation, manifested by excitement, restlessness, tremors and clonic convulsions, tinnitus, drowsiness. Then respiratory depression can occur and muerte16. These manifestations of toxicity are directly related to anesthetic potency.
Cardiovascular system. A level results in decreased myocardial electrical excitability, conduction velocity and force of contraction and dilation of arterioles. Lidocaine especially important antiarrhythmic effects, and then depresses the cough reflex, is a bronchodilator and decreases pressure intracraneana5, 16. It is important to be sure not to give an intravascular injection, which is why you should always aim before applying the anesthetic. Studies by Pateromichelakis17 concluded that arterial injection of lidocaine did not affect heart rate, mean arterial pressure and respiratory rate increases depressed.
Niwa et al.18 did a study to examine the safety of local anesthetic used with epinephrine and lidocaine 2% with epinephrine 1:80,000 in 27 patients with cardiovascular disease. Classification NYA (New York Heart Association) 18 was 9 patients class I, 11 classes II and 7 class III. They concluded that the use of lidocaine-epinephrine was safe and that there was very little effect on these hemodynamic enfermos19.
Vasoconstrictors. Often are added to local anesthetics to increase the duration of the medication, because they locate him longer. They are also useful for surgical procedures because it reduces the bleeding that occurs during it and facilitate visualization of the surgical field. Vasoconstrictor agents most commonly used are epinephrine and Felypressin, the latter has less cardiac adverse effect level. Hirota at al.20 in an electrocardiographic study of individuals with cardiovascular disease found that prilocaine with Felypressin caused smaller increase in cardiac function that lidocaine with epinephrine. Anyway, there is still much controversy about the effects of the sympathetic-adrenal vascoconstrictores in local anesthetics. However, other studies have shown that raising the concentration of epinephrine in plasma, and there are changes in cardiac function, peripheral resistance and pressure arterial21, 22. Adverse effects are produced by intravascular injection or a high dose, are alpha and beta adrenergic effects and present with anxiety, increased heart rate, palpitations, chest pain, cardiac arrhythmias, and even unemployment cardíaco5, 7:16. Because of these pharmacological actions to be taken into account the patient's medical history to use them properly and safely local anesthetics in dentistry. For these reasons the use of catecholamines should be restricted, and often avoid, in case of problems cardíacos7. In these patients (according to each particular case) is preferable to lidocaine, prilocaine or bupivacaine simple (without vasoconstrictor). Now you must remember that the duration of the anesthetic will be shorter and heavier bleeding than normal for what you should use a rapid and highly refined technique.
Allergy. The phenomena of allergy to local anesthetics are extremely rare and when they have found, using diphenhydramine, an antihistamine with good properties anestésicas23, 24. The true allergic reaction that is mediated by immunoglobulin E25. In many cases, what occur are pseudo-allergic reactions, toxicity phenomena and often psychosomatic reactions. It is also possible that some adverse reactions are due more to the preservatives and adrenalina23. Ucan at al.23 compared a group of 17 allergic patients (diphenhydramine) and a control group (prilocaine), and the two effects were obtained anestésicos23 appropriate.
CONCLUSIONS
1. Pain pathways and conduction of nerve impulses are conducted through myelinated and unmyelinated fibers and interacting with the Na and K pump
2. When local anesthetics are used should take account of their pharmacological actions, so that your application is safe and beneficial for the patient.
3. In patients with cardiac history is better not to use a vasoconstrictor. You can use 2% lidocaine, prilocaine 3%. In these cases we must remember that the anesthetic effect will be shorter and major bleeding.
4. To set the maximum dose of an anesthetic should be expressed in mg / kg and not according to the patient's age, it is necessary to know the patient's weight.
5. To determine the amount of anesthetic into mg, just enough to multiply the amount in ml, the percentage and number 10.
6. Lidocaine is a relatively safe anesthetic and is the most used.
7. Bupivacaine can be achieved in Radiology and is more potent than lidocaine; the duration of its action is more or less than 6 hours so that their postoperative analgesic effects can be very beneficial in accordance with the procedure followed. However, its safety margin is less than that of lidocaine.
This article reviews the literature and update the concepts of local anesthetic use in dentistry. Describe the pain pathways and the highlights in the pharmacology of local anesthetics are frequently used in dentistry. It describes the different types of available local anesthetics for dental use, the concentration of both the anesthetic and the vasoconstrictor agent, and the effects of each in the body.
Keywords: Anesthesia. Dentistry. Local anesthetics.
SUMMARY
To review the literature and to update the concepts about the use of dental local anesthetics, the present article describes the ways of pain and the most important aspects in the pharmacology of the more frequently used local anesthetics in dentistry. The different types of available local anesthetics for dental use are described, as well as the concentration including the vasoconstrictor action and their effects in the organism.
Key words: Anesthetics. Local anesthetics.
Colomb Med 2001 32: 121-124
The health professionals most frequently used local anesthetics are dentists. For this reason, it is worthwhile to recall and remember all the anatomical, pharmacological and techniques of local anesthesia in dentistry. This article aims to describe the pain pathways, nerve conduction and pharmacological aspects of conduction block.
Although the technique for application of the anesthetic is very important to know and use it correctly, this is not addressed, since it believes that its length and depth would result in another article on the subject. However, it is important to note that despite having very good technical skills, the clinician should not forget, much less minimize the theoretical basis of what is going to be reviewed below. In addition, the dentist must make a good clinical history to ascertain the general condition of the patient who is going to use local anesthetic drugs that might be taking and drug interactions.
WAYS OF PAIN
The site reached by the trigeminal sensory nerve fibers located in the brainstem and extends from the bridge to the top of the spinal segment, caudal sub nucleus be the end where myelinated and unmyelinated fibers. These afferent fibers are responsible for transmitting nerve impulses from different receptors that respond to noxious stimuli (nociceptors) to own central nervous system (CNS). Nociceptors are scattered throughout the human anatomy and through nerve fibers carry the momentum generated by painful sensations in the CNS. However, the reaction can be painful emotionally influenced by cultural factors, anxiety, previous experiences, among otras1.
It is important to be familiar with the anatomy of the trigeminal nerve or cranial nerve V and its three branches (most of which are sensory nerve fibers: ophthalmic and maxillary division and much of the mandible, which is mixed), because at this nerve passes the application of anesthetic to block sensation dolorosa2.
The cells (neurons) of the peripheral nerves are composed of a cell body (perikaryon) and an axon. The perikaryon is composed of a cell membrane (containing lipids and proteins), nucleus and cytoplasm. The axon is accompanied by supporting cells or Schwann and myelinated nerve fibers unmyelinated unlike consist of a single axon surrounded by Schwann cells, through the dissemination occurs axon of the nerve impulse. At rest the cell membrane is maintained with a negative electrical potential (K-) 1. If the membrane is excited, it generates an action potential and initiates the depolarization of her in a more or less slow during which the electrical potential within the cell becomes progressively less negative. After this phase ends and reverses the depolarization potential across the cell membrane and the interior becomes positively charged (Na +). After repolarization occurs until the cell becomes more negative again on the outside that is positive, and again achieved the resting potential.
BLOCKING OF NERVE CONDUCTION
Local anesthetics are drugs that reversibly block nerve impulse conduction, as it inhibits the excitation of the membrane of myelinated nerve fibers (A) and non-myelinated (C). Also slow down the process in the depolarization phase and reduce the inflow of sodium ions. That is, it reduces the permeability with respect to sodium (decreased rate of depolarization) thus the propagated action potential does not reach its threshold value and ultimately this determines a failure in nerve impulse conduction.
CLASSIFICATION OF LOCAL ANESTHETICS
Tables 1 and 2 describe the desirable properties of local anesthetics, the concentration and duration of action. In general local anesthetics used in dental procedures fall into two main groups: aminoésteres and aminoamidas1, 3.4.
Aminoésteres. They are para-aminobenzoic acid derivatives. The first local anesthetic used was cocaine in 1884 by Hall4, 5. In the group of stand aminoésteres procaine, cocaine, chloroprocaine and tetracaine.
Procaine. The synthesis of procaine (Novocain ®) will only be achieved until 1905 with the work of Einhron1, 3 and is the prototype of the local anesthetic properties but lacks topical anesthetic. Like many other anesthetics of the ester group is hydrolyzed to para-aminobenzoic acid (which inhibits the action of sulphonamides) and dimethylaminoethanol. The biotransformation is controlled by the enzyme pseudocholinesterase; therefore, its metabolism occurs in the blood. It is used in concentrations of 0.25% to 0.5% for infiltrative anesthesia, 0.5% to 2% to 10% blocks and epidural anesthesia. It can be used in combination with other drugs such as penicillin (penicillin G procaine) to prolong the pharmacological effect, allowing for slower absorption and causes of penicillin has demonstrable concentrations in blood and urine for extended periods. Procaine is now widely used in alternative medicine, although research dating back to 1925. One of the main uses in dentistry is the blockage of pain points in myofascial pain dysfunction syndrome (muscles of mastication). "Huneke neural therapy is a therapeutic system that exerts its action through the vegetative system with the application of either local anesthetic injected into the ground segmental disease, in this case segmental therapy, or to disconnect the interference field of illness "6.
Aminoamides. To this group belong anesthetics including lidocaine, prilocaine, mepivacaine, bupivacaine and etidocaine. These drugs are metabolized in the liver and not blood. The most commonly used in dentistry are lidocaine (Xylocaine ®) and prilocaine (Citanest ®, Pricanest ®). Lidocaine becomes monoetilglicinaxilidida and finally 4-hidroxixilidida. Lidocaine is absorbed in the urine.
Lidocaine. Lidocaine (Xylocaine ®), introduced in 1948 is one of the local anesthetic most commonly used because it produces more rapid anesthesia, intense, lasting and comprehensive peace that procaine and possesses very buenos1 topical effects, 5. It is the agent of choice in patients sensitive to esters. In addition to anesthetic is also used intravenously as an antiarrhythmic. It is available in liquid form for injection, jelly, cream, ointment and spray. In dentistry is available at Radiology of 1.8 ml of 2% with epinephrine 1:80,000, the maximum dose of lidocaine is 5 mg / kg, if used mg/kg5 vasoconstrictor is 7. To convert to milligrams percentage should be multiplied by 10. Therefore, a Radiology dental use has 1.8 ml x 2% x 10 = 36 mg of lidocaine. To express the concentration of epinephrine in micrograms are converted as follows:
This means that when one speaks of an epinephrine concentration of 1:80,000, is for each cubic foot (= 1 ml), 12.5 mg of epinephrine. The duration of action of lidocaine is approximately 2 hours and 4 times more potent than procaine. You can also get carpule lidocaine 2% without vasoconstrictor, and 2% with epinephrine 1:100,000. Also available in these concentrations in bottles of 50 ml. For topical spray is 10% and 2% jelly ointment 5%.
Prilocaine. The initiation and duration of their actions is a little longer than the lidocaína1. It takes approximately 2 hours and is 3 times more potent than procaine, has a toxic effect and is the exclusive secondary metahemoglobinemia7. In dentistry you can get in Radiology at concentrations of 2% and 3% (Citanest ®) octapresín (Felypressin ®) or 4% (Pricanest ®) without vasoconstrictor. It is used for infiltration anesthesia, regional block and cord.
Mepivacaine. Mepivacaine (Carbocaine ®) is an introduction of faster acting and longer duration than lidocaine; no topical properties. Its duration is approximately 2 hours and is twice as potent as procaine. It is used for infiltration anesthesia, blockade and spinal anesthesia. It is available in concentration of 3% without vasoconstrictor and 2% with epinephrine Neocobefrín (Levonordefrin ®) 1:20,000.
Bupivacaine. Bupivacaine (Marcaine ®) is four times more potent than lidocaine, its action is more delay, but it lasts about 6 horas5, 7. Bouloux et al.8 found that bupivacaine reduced pain in third molar surgery in the first 8 postoperative hours, compared with lidocaine. There was in that study, no difference in cardiac response or toxicity. There are several studies in the literature to compare the analgesic effects in postoperative joint surgery, intra-articular injection of bupivacaine alone, morphine alone and a combination of dos9-13. Furst at al.9 found that in post-operative arthroscopy of the temporomandibular joint bupivacaine alone provided a better analgesic effect. It is available in bottles with concentrations of 0.25% and 0.5% with or without epinephrine. The highest dose without epinephrine is 2.5 mg / kg and 4 mg/kg5 epinephrine. There are also carpule of 1.8 ml at concentrations of 0.5% with epinephrine 1:200,000. Maxillofacial surgeons use it a lot in orthognathic surgery, temporomandibular joint and trauma among others, for postoperative pain management for its long duration of action.
METABOLISM
The ester group local anesthetics are metabolized in the plasma by the enzyme pseudocholinesterase and a major metabolite is the para-aminobenzoic acid that appears to be responsible alérgicas1 reactions, 3. The amide anesthetics are metabolized in the liver and are not para-aminobenzoic acid. Local anesthetics are excreted in the urine.
PHARMACOLOGICAL ACTION OF LOCAL ANESTHETICS
It is important to consider the actions of local anesthetics on different body systems in order to assess adequately the phenomena of toxicity that might arise. Almost all dental procedures, including oral surgery, can be done under local anesthesia. When this is possible is preferable to do it this way general14 anesthesia. Studies Nkansah at al.15 found a mortality of 1.4 per 1'000, 000 2'830, 000 cases between 1973 and 1975 in Ontario (Canada).
Central nervous system. Produce central nervous system stimulation, manifested by excitement, restlessness, tremors and clonic convulsions, tinnitus, drowsiness. Then respiratory depression can occur and muerte16. These manifestations of toxicity are directly related to anesthetic potency.
Cardiovascular system. A level results in decreased myocardial electrical excitability, conduction velocity and force of contraction and dilation of arterioles. Lidocaine especially important antiarrhythmic effects, and then depresses the cough reflex, is a bronchodilator and decreases pressure intracraneana5, 16. It is important to be sure not to give an intravascular injection, which is why you should always aim before applying the anesthetic. Studies by Pateromichelakis17 concluded that arterial injection of lidocaine did not affect heart rate, mean arterial pressure and respiratory rate increases depressed.
Niwa et al.18 did a study to examine the safety of local anesthetic used with epinephrine and lidocaine 2% with epinephrine 1:80,000 in 27 patients with cardiovascular disease. Classification NYA (New York Heart Association) 18 was 9 patients class I, 11 classes II and 7 class III. They concluded that the use of lidocaine-epinephrine was safe and that there was very little effect on these hemodynamic enfermos19.
Vasoconstrictors. Often are added to local anesthetics to increase the duration of the medication, because they locate him longer. They are also useful for surgical procedures because it reduces the bleeding that occurs during it and facilitate visualization of the surgical field. Vasoconstrictor agents most commonly used are epinephrine and Felypressin, the latter has less cardiac adverse effect level. Hirota at al.20 in an electrocardiographic study of individuals with cardiovascular disease found that prilocaine with Felypressin caused smaller increase in cardiac function that lidocaine with epinephrine. Anyway, there is still much controversy about the effects of the sympathetic-adrenal vascoconstrictores in local anesthetics. However, other studies have shown that raising the concentration of epinephrine in plasma, and there are changes in cardiac function, peripheral resistance and pressure arterial21, 22. Adverse effects are produced by intravascular injection or a high dose, are alpha and beta adrenergic effects and present with anxiety, increased heart rate, palpitations, chest pain, cardiac arrhythmias, and even unemployment cardíaco5, 7:16. Because of these pharmacological actions to be taken into account the patient's medical history to use them properly and safely local anesthetics in dentistry. For these reasons the use of catecholamines should be restricted, and often avoid, in case of problems cardíacos7. In these patients (according to each particular case) is preferable to lidocaine, prilocaine or bupivacaine simple (without vasoconstrictor). Now you must remember that the duration of the anesthetic will be shorter and heavier bleeding than normal for what you should use a rapid and highly refined technique.
Allergy. The phenomena of allergy to local anesthetics are extremely rare and when they have found, using diphenhydramine, an antihistamine with good properties anestésicas23, 24. The true allergic reaction that is mediated by immunoglobulin E25. In many cases, what occur are pseudo-allergic reactions, toxicity phenomena and often psychosomatic reactions. It is also possible that some adverse reactions are due more to the preservatives and adrenalina23. Ucan at al.23 compared a group of 17 allergic patients (diphenhydramine) and a control group (prilocaine), and the two effects were obtained anestésicos23 appropriate.
CONCLUSIONS
1. Pain pathways and conduction of nerve impulses are conducted through myelinated and unmyelinated fibers and interacting with the Na and K pump
2. When local anesthetics are used should take account of their pharmacological actions, so that your application is safe and beneficial for the patient.
3. In patients with cardiac history is better not to use a vasoconstrictor. You can use 2% lidocaine, prilocaine 3%. In these cases we must remember that the anesthetic effect will be shorter and major bleeding.
4. To set the maximum dose of an anesthetic should be expressed in mg / kg and not according to the patient's age, it is necessary to know the patient's weight.
5. To determine the amount of anesthetic into mg, just enough to multiply the amount in ml, the percentage and number 10.
6. Lidocaine is a relatively safe anesthetic and is the most used.
7. Bupivacaine can be achieved in Radiology and is more potent than lidocaine; the duration of its action is more or less than 6 hours so that their postoperative analgesic effects can be very beneficial in accordance with the procedure followed. However, its safety margin is less than that of lidocaine.
