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Practical Phases of Local Anesthesia
1432
T h e journal of the American Dental Association and T h e Dental Cosmos
after eleven years of private practice limited exclusively to dentistry for chil dren, that if the patient conscientiously strives to carry out instructions to keep the mouth clean and returns for periodic check-up at least every three months, oral hygiene can and will reduce the ravages of dental decay. It is true that the chil dren in private practice cannot be con sidered a control group from a scientific standpoint, yet each child responds ac cording to the degree of cooperation
given, in that those children who are more conscientious show greater benefits. Scientists up to the present time have not discovered any serum, vaccine or specific whereby one can be inoculated and thereafter be forever free from den tal disease. Until more definite and posi tive methods of control are discovered, we must rely on oral hygiene as one of the most important factors in the preven tion o f dental disorders. 2039 North Prospect Avenue.
PRACTICAL PHASES OF LOCAL ANESTHESIA B y H o w a r d C . M i l l e r , D .D .S., Chicago,
I
N any surgical procedure within the mouth, the selection of an anesthetic is an extremely important step. T h e decision as to the anesthetic to be used should be based upon the training and experience of the operator, the physical condition of the patient and the type of operation to be performed. There is no one anesthetic best suited to all cases, but there is generally one that is best suited to the individual and to the operation. The successful operator selects the anes thetic best adapted to the case, the one from which the patient will receive the maximum benefit. I f regional or block anesthesia is the anesthetic of choice, it must be remem bered that its successful administration calls for scrupulous asepsis, proper anes thetic solution, a thorough knowledge of the anatomy of the parts involved and an exact technic. Clinical investigation and research have revealed certain facts Read before the Section on Oral Surgery, Radiology and Anesthesia at the SeventyFourth Annual Midwinter Meeting of the Chicago Dental Society, February 15, 1938. Jour. A .D .A. & D. Cos., Vol. 25, September 1938
111.
that should be of value to the dental practitioner, some of which m ay be stated as follow s: i. Procaine (novocaine) is the most effective and the safest local anesthetic agent available at the present time. This conclusion is based not alone upon the wide clinical application o f procaine solu tions, but also upon the accepted methods for determining the concentration per cent, efficiency ratio and toxicity, and the duration of action of local anesthetic solutions. Th e methods usually employed for such tests a r e : (a) Nerve block; e.g., the standard frog sciatic nerve method. (b) Efficiency on mucous membrane; by application to the human cornea and to the rabbit cornea. (c) Injection efficiency; by the stand ard wheal test on man. (d) T o x icity; by subcutaneous and vein administration in guinea-pigs, rats, cats and dogs, which also furnishes an index on respiration, heart condition and circulation.
M iller—Practical Phases of Local Anesthesia In making a survey of local anesthetic agents that have been used clinically, some more extensively than others, with a comparison as to their local effects, tol erated dosages, systemic toxicities and therapeutic margins o f safety, the fallacy of evaluating the anesthetic efficiency of a product on the basis of one test only can readily be seen. T h e broad field of usefulness can be determined only by noting the efficiency when applied under varying conditions, thus taking into ac count the variability as to absorption. Th e final analysis, in any case, must be governed by the margin of safety or the ratio between the effective and the mini mal toxic dose. For general usefulness, combining the maximal efficiency and minimal toxicity, procaine is easily the local anesthetic of choice today as in 1905, when it was first synthesized. 2. O f the available vasoconstrictors, epinephrine, cobefrin hydrochloride and neosynephrine seem to be the most desir able for dental operations. T h e practical usefulness of any local anesthetic depends primarily on the abolition or the blocking of sensory impulses from the field of op eration. In order to accomplish this with the local anesthetic agents available to day, the addition of a vasoconstrictor in some form is necessary to prolong anes thesia and to lessen the tendency toward toxic reactions due to too rapid absorp tion of the injected solution, thus facili tating dental operative procedures and eliminating as far as possible any systemic effects due to mass absorption of the lo cal anesthetic injected. Th e prolongation of anesthesia and the maximal limitation of systemic tox icity of local anesthetic compounds are best accomplished by the combined use of an anesthetic agent with maximal effi ciency and greatest margin of safety, with a vasoconstrictor o f the epinephrine type. 3. T h e solution should contain a mini mal amount of epinephrine (never ex ceeding 1 ¡50,000 solution) or one of the
1433
weaker vasoconstricting agents, such as cobefrin hydrochloride or neosynephrine. When the more dilute solutions of epi nephrine are used, or when one of the weaker vasoconstrictors is employed, the resulting change in blood pressure and pulse rate and the tendency to untoward and disturbing clinical reactions will be less pronounced. 4. Scrupulous asepsis must be adhered to throughout the entire procedure. A b solute asepsis in the mouth is, of course, not possible, but at least an aseptic tech nic can be followed by which the area of injection is protected from contamination. Instruments, syringes and needles should be sterilized by autoclaving or boiling, and the utmost care should be taken in preparation of the anesthetic solution. Th e mucous membrane of the region to be injected should be dried, after which some germicidal agent is applied to render the part as aseptic as possible. A sterile needle should be used for each subsequent injection. T h e same needle should never be used for additional deep block injections in various locations. W ith the increasing popularity of pre pared solutions sold to the profession in glass containers manufactured to fit syringes of various designs, there has been a tendency to use too little care in prep aration of the syringe and glass container before making the injection. When this form o f solution is used, the syringes should be autoclaved or boiled and the glass container should be placed in a germicidal solution for sufficient time to assure its asepsis. T h e anesthetic solution should be warmed approximately to body temperature. In m any cases, prophylac tic treatment is indicated before surgical interference is attempted. A neglected, inflamed and unhealthy mouth should be brought to as healthy condition as possible before regional or block anes thesia is used. Every attempt should be made to maintain a definite chain of asepsis and to prevent the introduction of bacteria through neglect of this phase,
1434
T h e Journal of the Am erican Dental Association and T h e Dental Cosmos
which is of great importance to any sur gical technic. 5. The confidence o f the patient should be gained beforehand in order that his excitement and fear may be allayed. He should be advised as to what is to be done and of the sensations and after effects to be expected. In an extremely nervous patient, in whom extensive op erative procedure m ay cause shock, some form of preoperative medication is indi cated. Administration of pentobarbital sodium (nembutal), 1.5 grains, from thirty minutes to one hour before opera tion, has been found very satisfactory in such cases. 6. T h e patient should always be in the recumbent or semirecumbent position when injection is made, never sitting up right in the dental chair. When this pro cedure is followed, fewer symptoms of toxic reaction will occur and the tend ency toward syncope will be greatly re duced'. 7. Injection should never be made into or through an infected or inflamed area. This precaution hardly seems necessary, but, with the m any acute infections that follow injection, particularly in the third molar area, it apparently will bear repe tition. In dealing with any acute type of den tal infection, great care must be exercised in the use of a local anesthetic, since, even in the early stages, the extent of tissue involvement and the virulence o f the organism are unknown. 8. T h e solution should be injected slowly, with only sufficient pressure to discharge it into the tissues at the en trance or exit of the nerve trunk from its bony canal, or into the soft tissues along the mucobuccal fold of the teeth to be anesthetized. I f the needle is in serted in the dense surrounding gum tis sue and the solution deposited under considerable pressure, far more primary pain will result, with an excessive amount of tissue irritation and postoperative dis comfort. T h e solution should be at or
near body temperature at the time of in jection. 9. Care should be taken never to make an injection into a vein or artery, because this greatly increases the toxicity of the anesthetic solution. It m ay be prevented by moving the needle back and forth slightly while the solution is being dis charged ; or the plunger m ay be retracted in order to determine whether a blood vessel has been entered. 10. Th e maintenance of normal breath ing throughout is o f utmost importance. Frequently, a patient will hold his breath or the breathing m ay become shallow, particularly with the first inser tion of the needle. This results in a lack of oxygen in the system (anoxemia) and very often is a factor in the development o f some of the unfavorable symptoms. 1 1 . T h e patient should be restrained from raising his head to expectorate into the cuspidor immediately after injec tion. Such exertion m ay precipitate a severe reaction, which can be avoided by supplying a small basin for this pur pose. 12. In the presence o f definite heart impairment or other serious physical dis ability, operative procedure should be restricted to a small area, which can be anesthetized by a minimal number o f in jections, and the smallest possible amount of solution. 13. I f there are signs of toxic reaction, such as apprehensiveness, tremor, heart consciousness, labored respiration, rapid pulse, pallor, beads of perspiration or syncope, the patient should immediately be placed in a horizontal position with the head lower than the body. T h e face is wiped or slapped with a towel wrung from cold water and one o f the indirect heart stimulants, such as aromatic spirits of ammonia or spirits of camphor, is ad ministered by inhalation. Stimulation is best supplied by aromatic spirits o f am monia pearls, which are quickly broken and held close to the nostrils, or by plac ing fresh aromatic spirits of ammonia on
M iller— Practical Phases of Local Anesthesia
1435
a piece of gauze and forcing the patient thesia. M an y operators attempt to make to inhale as deeply as possible. I f the deep block injections in a mechanical reaction is not so severe as to cause loss of w ay, following a technical procedure consciousness, from 20 to 30 drops of learned through lectures or from articles aromatic spirits of ammonia in a small dealing entirely with technical phases. amount o f water m ay be administered by Th e operator should be able to visualize the structures through which the needle mouth. In cases of respiratory failure, artificial must pass, the bony surface and the respiration should be instituted and the nervous tissue at the point of injection. air passages should be kept free of any W hen this knowledge is complete, local obstruction. T h e use of pure oxygen or anesthesia ceases to be a mechanical pro cedure and becomes a definite surgical oxygen with 5 or 10 per cent carbon di oxide should supplement the artificial technic based entirely upon anatomic landmarks. respiration. T h e patient should receive supportive medication, such as a hypo 15. A n exact technic, based upon the dermic injection of caffeine and sodium knowledge of a simple, safe and efficient benzoate 7.5 grains ; camphor in oil, or procedure, is essential to the successful strychnine one-sixtieth to one-thirtieth use of a local anesthetic. T o attempt to grain. advance any particular claims or advan tages of one technic over another is not In cardiac failure, it is necessary to the object o f this presentation. maintain respiration and employ suppor tive medication. In cases of collapse of In view of the fact that our technical patients suffering from angina pectoris, procedures are based entirely upon ana coronary disease or epileptic seizures, a tomic relations in the human skull, it is vasodilator, such as amyl nitrate by in obvious that there cannot be much varia tion in the manner of injection. Occasion halation, and hypodermic injections of nitroglycerine one-hundredth to oneally, refinements in technic are offered hundred-fiftieth grain should be em in an attempt to simplify the various ployed. In cardiac failure, hypodermic methods of injection, but, in most in injection of digifoline should be used, stances, these are based upon the pro and, in extreme cases, 1 cc. o f epineph cedures followed by those who first pre rine, injected hypodermically, has been sented the technic for blocking various found effective. branches o f the fifth cranial nerve. In all cases of toxic reaction, the pa It is hoped that the material presented tient must be kept under close observa will assist the general dentist and permit tion and immediate and proper treatment a more critical viewpoint, a better under be instituted at once if serious conse standing o f products in use and a more quences are to be avoided. careful observation o f the reaction of 14. A thorough knowledge of the the patient to the injected solution and anatomy of the parts involved is essen the anesthetic result. tial to the successful use of local anes 55 East Washington Street.
T h e journal of the American Dental Association and T h e Dental Cosmos
after eleven years of private practice limited exclusively to dentistry for chil dren, that if the patient conscientiously strives to carry out instructions to keep the mouth clean and returns for periodic check-up at least every three months, oral hygiene can and will reduce the ravages of dental decay. It is true that the chil dren in private practice cannot be con sidered a control group from a scientific standpoint, yet each child responds ac cording to the degree of cooperation
given, in that those children who are more conscientious show greater benefits. Scientists up to the present time have not discovered any serum, vaccine or specific whereby one can be inoculated and thereafter be forever free from den tal disease. Until more definite and posi tive methods of control are discovered, we must rely on oral hygiene as one of the most important factors in the preven tion o f dental disorders. 2039 North Prospect Avenue.
PRACTICAL PHASES OF LOCAL ANESTHESIA B y H o w a r d C . M i l l e r , D .D .S., Chicago,
I
N any surgical procedure within the mouth, the selection of an anesthetic is an extremely important step. T h e decision as to the anesthetic to be used should be based upon the training and experience of the operator, the physical condition of the patient and the type of operation to be performed. There is no one anesthetic best suited to all cases, but there is generally one that is best suited to the individual and to the operation. The successful operator selects the anes thetic best adapted to the case, the one from which the patient will receive the maximum benefit. I f regional or block anesthesia is the anesthetic of choice, it must be remem bered that its successful administration calls for scrupulous asepsis, proper anes thetic solution, a thorough knowledge of the anatomy of the parts involved and an exact technic. Clinical investigation and research have revealed certain facts Read before the Section on Oral Surgery, Radiology and Anesthesia at the SeventyFourth Annual Midwinter Meeting of the Chicago Dental Society, February 15, 1938. Jour. A .D .A. & D. Cos., Vol. 25, September 1938
111.
that should be of value to the dental practitioner, some of which m ay be stated as follow s: i. Procaine (novocaine) is the most effective and the safest local anesthetic agent available at the present time. This conclusion is based not alone upon the wide clinical application o f procaine solu tions, but also upon the accepted methods for determining the concentration per cent, efficiency ratio and toxicity, and the duration of action of local anesthetic solutions. Th e methods usually employed for such tests a r e : (a) Nerve block; e.g., the standard frog sciatic nerve method. (b) Efficiency on mucous membrane; by application to the human cornea and to the rabbit cornea. (c) Injection efficiency; by the stand ard wheal test on man. (d) T o x icity; by subcutaneous and vein administration in guinea-pigs, rats, cats and dogs, which also furnishes an index on respiration, heart condition and circulation.
M iller—Practical Phases of Local Anesthesia In making a survey of local anesthetic agents that have been used clinically, some more extensively than others, with a comparison as to their local effects, tol erated dosages, systemic toxicities and therapeutic margins o f safety, the fallacy of evaluating the anesthetic efficiency of a product on the basis of one test only can readily be seen. T h e broad field of usefulness can be determined only by noting the efficiency when applied under varying conditions, thus taking into ac count the variability as to absorption. Th e final analysis, in any case, must be governed by the margin of safety or the ratio between the effective and the mini mal toxic dose. For general usefulness, combining the maximal efficiency and minimal toxicity, procaine is easily the local anesthetic of choice today as in 1905, when it was first synthesized. 2. O f the available vasoconstrictors, epinephrine, cobefrin hydrochloride and neosynephrine seem to be the most desir able for dental operations. T h e practical usefulness of any local anesthetic depends primarily on the abolition or the blocking of sensory impulses from the field of op eration. In order to accomplish this with the local anesthetic agents available to day, the addition of a vasoconstrictor in some form is necessary to prolong anes thesia and to lessen the tendency toward toxic reactions due to too rapid absorp tion of the injected solution, thus facili tating dental operative procedures and eliminating as far as possible any systemic effects due to mass absorption of the lo cal anesthetic injected. Th e prolongation of anesthesia and the maximal limitation of systemic tox icity of local anesthetic compounds are best accomplished by the combined use of an anesthetic agent with maximal effi ciency and greatest margin of safety, with a vasoconstrictor o f the epinephrine type. 3. T h e solution should contain a mini mal amount of epinephrine (never ex ceeding 1 ¡50,000 solution) or one of the
1433
weaker vasoconstricting agents, such as cobefrin hydrochloride or neosynephrine. When the more dilute solutions of epi nephrine are used, or when one of the weaker vasoconstrictors is employed, the resulting change in blood pressure and pulse rate and the tendency to untoward and disturbing clinical reactions will be less pronounced. 4. Scrupulous asepsis must be adhered to throughout the entire procedure. A b solute asepsis in the mouth is, of course, not possible, but at least an aseptic tech nic can be followed by which the area of injection is protected from contamination. Instruments, syringes and needles should be sterilized by autoclaving or boiling, and the utmost care should be taken in preparation of the anesthetic solution. Th e mucous membrane of the region to be injected should be dried, after which some germicidal agent is applied to render the part as aseptic as possible. A sterile needle should be used for each subsequent injection. T h e same needle should never be used for additional deep block injections in various locations. W ith the increasing popularity of pre pared solutions sold to the profession in glass containers manufactured to fit syringes of various designs, there has been a tendency to use too little care in prep aration of the syringe and glass container before making the injection. When this form o f solution is used, the syringes should be autoclaved or boiled and the glass container should be placed in a germicidal solution for sufficient time to assure its asepsis. T h e anesthetic solution should be warmed approximately to body temperature. In m any cases, prophylac tic treatment is indicated before surgical interference is attempted. A neglected, inflamed and unhealthy mouth should be brought to as healthy condition as possible before regional or block anes thesia is used. Every attempt should be made to maintain a definite chain of asepsis and to prevent the introduction of bacteria through neglect of this phase,
1434
T h e Journal of the Am erican Dental Association and T h e Dental Cosmos
which is of great importance to any sur gical technic. 5. The confidence o f the patient should be gained beforehand in order that his excitement and fear may be allayed. He should be advised as to what is to be done and of the sensations and after effects to be expected. In an extremely nervous patient, in whom extensive op erative procedure m ay cause shock, some form of preoperative medication is indi cated. Administration of pentobarbital sodium (nembutal), 1.5 grains, from thirty minutes to one hour before opera tion, has been found very satisfactory in such cases. 6. T h e patient should always be in the recumbent or semirecumbent position when injection is made, never sitting up right in the dental chair. When this pro cedure is followed, fewer symptoms of toxic reaction will occur and the tend ency toward syncope will be greatly re duced'. 7. Injection should never be made into or through an infected or inflamed area. This precaution hardly seems necessary, but, with the m any acute infections that follow injection, particularly in the third molar area, it apparently will bear repe tition. In dealing with any acute type of den tal infection, great care must be exercised in the use of a local anesthetic, since, even in the early stages, the extent of tissue involvement and the virulence o f the organism are unknown. 8. T h e solution should be injected slowly, with only sufficient pressure to discharge it into the tissues at the en trance or exit of the nerve trunk from its bony canal, or into the soft tissues along the mucobuccal fold of the teeth to be anesthetized. I f the needle is in serted in the dense surrounding gum tis sue and the solution deposited under considerable pressure, far more primary pain will result, with an excessive amount of tissue irritation and postoperative dis comfort. T h e solution should be at or
near body temperature at the time of in jection. 9. Care should be taken never to make an injection into a vein or artery, because this greatly increases the toxicity of the anesthetic solution. It m ay be prevented by moving the needle back and forth slightly while the solution is being dis charged ; or the plunger m ay be retracted in order to determine whether a blood vessel has been entered. 10. Th e maintenance of normal breath ing throughout is o f utmost importance. Frequently, a patient will hold his breath or the breathing m ay become shallow, particularly with the first inser tion of the needle. This results in a lack of oxygen in the system (anoxemia) and very often is a factor in the development o f some of the unfavorable symptoms. 1 1 . T h e patient should be restrained from raising his head to expectorate into the cuspidor immediately after injec tion. Such exertion m ay precipitate a severe reaction, which can be avoided by supplying a small basin for this pur pose. 12. In the presence o f definite heart impairment or other serious physical dis ability, operative procedure should be restricted to a small area, which can be anesthetized by a minimal number o f in jections, and the smallest possible amount of solution. 13. I f there are signs of toxic reaction, such as apprehensiveness, tremor, heart consciousness, labored respiration, rapid pulse, pallor, beads of perspiration or syncope, the patient should immediately be placed in a horizontal position with the head lower than the body. T h e face is wiped or slapped with a towel wrung from cold water and one o f the indirect heart stimulants, such as aromatic spirits of ammonia or spirits of camphor, is ad ministered by inhalation. Stimulation is best supplied by aromatic spirits o f am monia pearls, which are quickly broken and held close to the nostrils, or by plac ing fresh aromatic spirits of ammonia on
M iller— Practical Phases of Local Anesthesia
1435
a piece of gauze and forcing the patient thesia. M an y operators attempt to make to inhale as deeply as possible. I f the deep block injections in a mechanical reaction is not so severe as to cause loss of w ay, following a technical procedure consciousness, from 20 to 30 drops of learned through lectures or from articles aromatic spirits of ammonia in a small dealing entirely with technical phases. amount o f water m ay be administered by Th e operator should be able to visualize the structures through which the needle mouth. In cases of respiratory failure, artificial must pass, the bony surface and the respiration should be instituted and the nervous tissue at the point of injection. air passages should be kept free of any W hen this knowledge is complete, local obstruction. T h e use of pure oxygen or anesthesia ceases to be a mechanical pro cedure and becomes a definite surgical oxygen with 5 or 10 per cent carbon di oxide should supplement the artificial technic based entirely upon anatomic landmarks. respiration. T h e patient should receive supportive medication, such as a hypo 15. A n exact technic, based upon the dermic injection of caffeine and sodium knowledge of a simple, safe and efficient benzoate 7.5 grains ; camphor in oil, or procedure, is essential to the successful strychnine one-sixtieth to one-thirtieth use of a local anesthetic. T o attempt to grain. advance any particular claims or advan tages of one technic over another is not In cardiac failure, it is necessary to the object o f this presentation. maintain respiration and employ suppor tive medication. In cases of collapse of In view of the fact that our technical patients suffering from angina pectoris, procedures are based entirely upon ana coronary disease or epileptic seizures, a tomic relations in the human skull, it is vasodilator, such as amyl nitrate by in obvious that there cannot be much varia tion in the manner of injection. Occasion halation, and hypodermic injections of nitroglycerine one-hundredth to oneally, refinements in technic are offered hundred-fiftieth grain should be em in an attempt to simplify the various ployed. In cardiac failure, hypodermic methods of injection, but, in most in injection of digifoline should be used, stances, these are based upon the pro and, in extreme cases, 1 cc. o f epineph cedures followed by those who first pre rine, injected hypodermically, has been sented the technic for blocking various found effective. branches o f the fifth cranial nerve. In all cases of toxic reaction, the pa It is hoped that the material presented tient must be kept under close observa will assist the general dentist and permit tion and immediate and proper treatment a more critical viewpoint, a better under be instituted at once if serious conse standing o f products in use and a more quences are to be avoided. careful observation o f the reaction of 14. A thorough knowledge of the the patient to the injected solution and anatomy of the parts involved is essen the anesthetic result. tial to the successful use of local anes 55 East Washington Street.