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Anesthesia for Abdominal Surgery
Anesthesia for Abdominal Surgery MARY KARP, M.D. *
c. S. YEIN, M.D. **
IN general, the choice of an anesthetic agent and method depends on a proper understanding of a given situation by the anesthesiologist, surgeon and, when possible, the patient. There is no substitute for an experienced team. The agent selected or the method used is of secondary importance. This is attested by the fact that a variety of agents have proved successful in the hands of one anesthesiologist or another. The major advances have not been in the discovery of new agents or techniques but rather in a fuller application of the basic sciences to the practice of anesthesiology. Of greatest importance is a thorough understanding of physiology and pharmacology of circulation and respiration, combined with clinical training. ANESTHETIC METHODS AND AGENTS
Generally speaking, abdominal surgery is performed under one or more of the following anesthetic methods and agents: 1. Regional block with secobarbital (Seconal) or thiopental (Pentothal) hypnosis 2. Gas-ether with thiopental induction and with or without a muscle relaxant 3. Thiopental, nitrous oxide and oxygen with a muscle relaxant
Ether Ether still continues to hold first place as the safest agent. It yields all depths of anesthesia with adequate relaxation for abdominal exposure and with little immediate risk to the patient. Even in small quantities it tends to stabilize a cyclopropane or Pentothal-curare anesthesia .. It has the great advantage of being a respiratory stimulant except in deep
* Assistant Professor of Surgery and Director of Anesthesia, Northwestern University Medical School, Chicago.
** Fellow in Surgery (Anesthesiology), Northwestern University Medical School, Chicago. 17
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Mary Karp, C. S. Yein
planes of anesthesia. This, plus a slow action and its 100 per cent potency, combine to make it universally popular. Our concept concerning ether has been changing gradually. In the past it has been considered a poor choice for patients with heart or lung disease. Many anesthesiologists now consider ether to be the agent of choice in such conditions. It should be the basic potent anesthetic agent, and all other anesthetic drugs should show specific advantages before being selected in preference to ether. However, one must be mindful of its disadvantages. Symptoms of shock may be exhi.bited by a patient during an operation as a result of a deep ether anesthesia. The functioning power of the pancreas is disturbed, preventing the conversion of glucose into glycogen, storage of glycogen in the liver and also interfering with the metabolism of glycogen already present there. Other disadvantages are reduced renal function, postanesthetic toxic symptoms and postanesthetic respiratory morbidity. For these reasons ether must not be used as the sole agent for producing profound abdominal anesthesia. Cyclopropane
Cyclopropane is a 100 per cent potent agent permitting fast, smooth progress throughout all stages of anesthesia. This fact alone makes its use a hazard by the untrained or partially trained administrators of anesthetic drugs. The tendency at the present time is to use cyclopropane with a combination of other drugs rather than a sole agent; that is, to produce a "balanced mixture" with ethylene, nitrous oxide, ether or curare in varying combinations as needed. Until the full significance of the effect on the heart is understood this drug should be contraindicated in those patients with cardiac disease. However, one of its first clinical users, Dr. Griffith, stated in this regard: "My own opinion, based on long clinical experience, is almost exactly the opposite-that generally speaking, cyclopropane is the anesthetic of choice for patients with serious heart disease who must undergo major surgical procedures." Pentothal Sodium
Pentothal enjoys great popularity and'widespread use because of its smooth, rapid, pleasant induction, ease of administration and minimal after-effects. Approximately 90 per cent of all abdominal cases receive Pentothal as an induction agent. It should seldom be used alone but should be combined with nitrous oxide-oxygen, local or regional anesthesia and curare. When shock is present, or hemorrhage, or extreme debility, it should be administered with extreme caution, if at all. Because it causes constriction of the bronchioles and is a respiratory depressant, it is contraindicated in those patients who have respiratory
Anesthesia for Abdominal Surgery
19
obstructions, acute pulmonary disease or asthma. The hypertensive patient takes pentothal poorly often suffering hypotensive effects. The aged and very young have difficulty in maintaining satisfactory physiological balance during the course of intravenous anesthesia. Another anesthetic agent will be preferable in these cases. Muscle Relaxants
Muscle relaxants available to the anesthetist have increased in number in recent years, so that well over a dozen different products are now in commercial use. Each one has advantages, variations in duration of action and depth of relaxation, and has disadvantages. Of special interest is the most recently introduced, succinylcholine chloride (Anectine), a short-acting curarizing agent whose action is so brief that it lends itself to administration by intravenous continuous drip. Recovery of full muscle tone and reflex activity follows within one to five minutes after the infusion is discontinued. This minute-to-minute control offers a great safety factor to curare administration, and it is predicted that this drug will become the muscle relaxant of choice for abdominal surgery. The curare drugs may be combined with all anesthetic agents, permitting smaller doses of analgesic or hypnotic drugs. They have excellent muscle-relaxing effects when combined with cyclopropane, neither increasing nor decreasing the irritability of the heart in this combination. Their use should be restricted to those administrators capable of handling the apneic patient. This group of drugs has such powerful action and is so simple to administer that the unwary and inexperienced can use it and have used it to cover up errors of judgment and technique. Large series have been compiled showing that curare is a sole or major cause of anesthesia morbidity and mortality. One wonders whether such large scale studies are statistically correct in all details or whether the results obtained may be interpreted as due to poor usage of a good drug. Curare is a useful adjunct to anesthesia; in many instances it has proved life-saving. Further investigation and research will set its true pattern of clinical application. Spinal Anesthesia
Spinal anesthesia, unlike inhalation anesthesia, does not have the universal approval of all members of the medical profession. Some reserve the method for those cases for which inhalation or local anesthesia cannot possibly be used. Others use spinal anesthesia routinely for all surgical interventions below the diaphragm. The success or failure of spinal anesthesia is directly proportional to the preanesthetic evaluation of the patient, with the intelligent selection of the patient suitable for
20
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the method and with adequate preanesthetic medications. It is best to maintain most patients receiving sp:nal anesthesia for abdominal surgery in a light state of hypnosis and sedation throughout the operation by means of a slow continuous intravenous drip of 0.2 to 0.5 per cent Pentothal Sodium. This reduces the objectionable features of patient awareness, the discomfort of maintaining a restrained position for any length of time, and traction reflexes. Pontocaine hydrochloride continues to be the drug of choice in most clinics. It is usually made hyperbaric by weighting it with 10 per cent dextrose, or hypobaric with triple distilled water. The use of the continuous fractional method, utilizing the malleable spinal needle or the No.3 ureteral catheter, has increased the safety of the method and prolonged its action for any length of surgical procedure. It must be remembered that the chemotoxic effects of various spinal agents aggravate pre-existing neurospinal diseases. Sensory disturbances, cranial nerve involvement (especially the sixth), and impaired bladder and rectal functions are occasional sequelae. The "spinal headache" still continues to occur in from 2 to 15 per cent of cases, and present day methods and treatment have not prevented or cured this complication. Also more serious spinal root and cord disturbances may occur. The possibility of septic meningitis is ever present, in spite of apparently aseptic technique of administration. Neurological sequelae have been estimated at 1 in 3000 to 1 in 10,000 cases. In spite of the complications listed above, it is the consensus of most anesthesiologists that the benefits of a well conducted spinal anesthesia in selected cases, especially for lower abdominal surgery, easily counterbalance the small risk involved. Certainly it provides ideal conditions for the surgeon-a completely relaxed abdomen with contracted intestines, quiet respirations and usually reduced bleeding. Balanced Anesthesia
Balanced anesthesia is produced by the administration of small amounts of several anesthetic drugs, each with a specific function; thus avoiding large toxic doses of any individual drug alone. A few years ago, ether or chloroform was used as a sole anesthetic agent throughout the surgical procedure. Gradually the pattern of anesthesia has changed to the use of multiple anesthetic drugs, which, because of their small doses, provide a wide margin of safety to the patient while producing excellent working conditions for the surgeon. Most present day anesthetic techniques for abdominal surgery involve some combination of drugs in a balanced manner; such as nitrous oxide-oxygen, Pentothal and curare; and cyclopropane, ether and curare; nitrous oxide, cyclopropane and curare. A more complicated balanced technique includes the use of secobarbital, meperidine hydrochloride (Demerol), Pentothal, curare and nitrous oxide. In such combinations the anesthesiologist must deter-
Anesthesia for Abdominal Surgery
21
mine, as the anesthesia progresses, if there is need for hypnosis, analgesia, reduction of metabolism, depression of reflexes or relaxation of musculature. Endotracheal Intubation
Endotracheal intubation is of great value in abdominal anesthesia. It is an excellent means of maintaining an adequate airway for the patient, preventing the entrance of vomitus or blood into the lung and permitting suctioning of the tracheobronchial tree. It provides means of artificial pulmonary ventilation to augment depressed respiration or to control respirations completely. By its means, the respiratory system can be separated from the gastrointestinal tract, thus avoiding distention of the stomach from gaseous agents. It promotes quiet breathing and helps to minimize the amount of anesthetic agent required. For many anesthesiologists the cuffed endotracheal tube has become a routine airway in anesthesia for upper abdominal surgery. Assisted or Controlled Respiration
Assisted or controlled respiration has been widely used in operations of the upper abdomen and to a lesser degree of the lower abdomen. It has been shown that anesthesia deep enough to produce relaxation of abdominal muscles causes various degrees of respiratory depression, either due to direct depression of the respiratory center or to paresis of the intercostal muscles. The use of assisted or controlled respiration permits the anesthesiologist to use those potent anesthetics, depressant drugs and muscular rela:l\ant agents which provide sufficient relaxation for abdominal surgery, without interfering with adequate ventilation. When the surgical procedure requires a quiet respiration, as in abdominal operations, assisted or controlled respirations can be valuable. Whenever curare is used, the assisted respiration technique should be routinely applied. It will also spare the patient the added effort of breathing against the weight of abdominal viscera, surgical packs, and tired assistants against the diaphragm. SUPPORTIVE PROCEDURES
Anesthesiologists have been aided by certain modern procedures in their attempts to attain the ideal-safety and comfort to the patient, a relaxed quiet abdomen with little bleeding and speedy uneventful recovery. I-Norepinephrine
Until the advent of l-norepinephrine bitartrate, epinephrine, d-desoxyephedrine and similar drugs were the vasodepressors most commonly
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Nlary Karp, C. S. Yein
used by the anesthetist to combat hypotension during regional analgesia and other shock states. A study of their physiological action reveals that their pressor activity is brought about mainly by an increase in cardiac output. l-Norepinephrine (Arterenol, Levophed) though synthesized by Stoltz and Flacher in 1904, was introduced into clinical use in 1949 and 1950. It is probably the most powerful over-all vasoconstrictor drug available to the anesthesiologist. It is the physiological transmitter to most adrenergic nerves which are responsible for the control of the blood pressure; therefore, it is a suitable drug for combating hypotensive circulatory states due to a lowering of peripheral resistance. It causes no, or very little, increase in minute volume of the heart and probably some vasodilation of the coronaries. The pressor effect is not attended by increased heart rate, cardiac output or central nervous system stimulation. Its toxicity is eight times less than that of epinephrine. It produces a bradycardia due to vagal reflexes from the carotid sinus or ,the aortic arch, which is prevented by atropine. In the early phases of shock there is an over-all increase in vascular tonus which becomes progressively impaired until in the last or irreversible phase there is loss of small vessel tone and a pooling of blood. In advanced shock, fluid replacements are of no immediate benefit, and only a drug like norepinephrine may reverse this condition by increasing resistance through vasoconstriction. This drug has distinct value in sustaining the blood pressure of severe hypertensive patients, or patients with diseases of the coronary arteries. In these patients, hypotension during surgery may cause cerebral thrombosis or myocardial ischemia. Another use is to counteract the collapse under spinal anesthesia, where there has been no blood loss, but circulatory collapse has occurred with reduced cardiac output and lowered peripheral resistance. In severe sudden hemorrhage during surgery, norepinephrine will aid the compensatory mechanisms to maintain vasoconstriction of arterioles; thus it may be a life-saving bridging measure until fluid replacements are adequate. It will increase the blood pressure to normal rates following the use of hypotensive producing drugs such as pentomethonium and hexamethonium compounds. The duration of action of norepinephrine is very short; for this reason it can be readily controlled. It is administered in the following manner; 4 mg. of the drug are added to 1 liter of diluent (saline or dextrose in water) to make a strength of 4 micrograms per cubic centimeter. An infusion is started at the rate of 40 to 60 drops per minute; blood pressure readings are then checked at one to two minute intervals until the desired blood pressure is reached. The rate of flow is then reduced, usually to 6 to 10 drops per minute. This is sufficient to sustain the level desired in most cases. As soon as possible the drug is discontinued. Observation is the only satisfactory guide to correct dosage.
Anesthesia for Abdominal Surgery
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A word of caution: several cases of gangrene of the superficial structures of the extremities have been reported. These are due to extravasation of the drug, or to venospasm from the powerful action of the vasoconstrict ant itself. To avoid this complication the intravenous needle should be well cannulated, the site of puncture should be the veins of the muscular regions of the arm and leg instead of the hand or foot, and the patient should be weaned from norepinephrine as soon as his condition will permit. Then warm moist packs to the extremities and intravenous procaine (0.1 per cent) may increase the circulation to the extremities sufficiently to counteract the initial ischemia of the tissues. Arterial Transfusion
One of the serious complications resulting in death during abdominal surgery is acute massive hemorrhage due to accidental rupture of the large blood vessels. Arterial transfusion of whole blood may be a lifesaving procedure under these circumstances. The indications during abdominal surgery for arterial transfusion are not many: its use is limited to specific situations such as profound shock where there is loss of small vessel tone and pooling of blood. Here intravenous transfusions will be fruitless. Another indication for the use of this technique is in preparation of the patient undergoing emergency operation for massive hemorrhage from the upper gastrointestinal tract. Though there is some question conceming the underlying action and effect of arterial transfusion, clinicians throughout the country have seen its dramatic effects. Equipment should be kept sterilized and available for emergency use. Gangrene of the extremity distal to the arterial puncture has been reported and this complication should be borne in mind whenever the use of the method is contemplated. Hypotensive Technique
The prevention of quantitatively significant bleeding in the operative field can be controlled by many ways: by posture, by profound general anesthesia, by arteriotomy, by nerve block and by means of methonium compounds and other blocking agents. When bleeding is controlled, the work of the surgeon is facilitated and operating time is shortened. The need for blood transfusions with the accompanying risk is reduced to a minimum. The use of various ganglionic blocking drugs and methods to induce a hypotensive state with a bloodless field was introduced into anesthesia in Great Britain. Its value and safety has been investigated extensively. "Controlled hypotension" demands an adequate preoperative blood volume, the immediate replacement of all blood lost, an absolutely patent airway and complete oxygenation, and provisions for expert and meticulous postoperative care. It should never be employed
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in the absence of a specific or urgent indication nor for the convenience of surgery. It must never be employed by the unwary, or by the unskilled. It has questionable value in intra-abdominal surgery. In fact, the upper abdominal and pelvic sites are the most difficult to keep bloodless. In some of the extensive radical dissections this technique may be of value. A new drug, a thiophanium derivative (Arfonad), has been introduced which has the advantages of short action and controllability. It appears to be the drug of choice when this technique is indicated. The number of complications associated with this technique indicates that it should be used with great caution. Blocking Agents of Long Duration
The physician has long been in quest of a local anesthetic agent with low toxicity and prolonged action. Such a drug injected into the intercostal nerves or paravertebrally would reduce the postoperative pain of abdominal surgery, permitting unhampered ventilation, free body activity and reduced postoperative hospitalization. Several drugs have been introduced for this purpose. By far the most successful agent, judging from clinical reports, is Efocaine, a solution of procaine 1 per cent; procaine hydrochloride 0.25 per cent; and butyl-p-aminobenzoate 5 per cent in a solvent polyethyleneglycol-300, 2 per cent; propyleneglycol 78 per cent and water. However, in recent months clinical evidence from case reports seem to indicate that Efocaine has caused perirectal sloughs, unilateral anhydrosis, severe neuralgia, postinjection neuritis and pain, atonic bladder and long-lasting and probably permanent motor paralysis of the lower extremities. It would appear, from the increasing number of reports of complications from the use of this drug, that it should be used with extreme caution if at all. Inhalation of Wetting Agents and EnzYIlles Postoperatively
General anesthesia for abdominal surgery may be followed postoperatively by prolonged periods of respiratory depression, loss of body tone, and inability to expectorate lung secretions because of pain and weakness. The chief damage of retained secretions is airway obstruction. This may result in atelectasis, emphysema, or infection distal to the obstruction. Some of these sequelae require prolonged medical care and may be a cause of disability or limited activity for long periods of time. Hence, the importance of maintaining a moist atmosphere in the tracheobronchial tree and liquefying and removing sections before the occurrence of airway obstruction and the potential complications. Of the number of wetting agents and enzymes tested, two drugs are used most frequently at the present time to liquefy lung secretions: a new detergent, Alevaire, and a trypsin enzyme, Tryptar. Alevaire is an aqueous solution of a new synthetic detergent (a mem-
Anesthesia for Abdominal Surgery
25
ber of the alkylaryl polyther alcohols) in combination with sodium bicarbonate 2 per cent and glycerin 5 per cent. It is particularly suited for medical use because of its activity in lowering surface tension, and its chemical inertness. Its thinning effect on highly viscid sputum is constant and dependable and without toxicity. It is indicated for the treatment of diseases of the lungs accompanied or complicated by the presence of excessive or thickened bronchopulmonary secretions. It is administered by aerosol nebulizer, mask or tent, its vehicle being air or oxygen. Up to 500 cc. can be nebulized per day without producing toxic symptoms. The length of treatment varies, usually from 24 to 72 hours. Trypsin, a proteolytic enzyme obtained from the pancreas of all animals, also has the property of thinning and digesting tenacious secretions within the tracheobronchial tree. It is administered by means of nebulizer or mask, with oxygen as a vehicle. The initial adult dose is 75,000 units of trypsin in Sorenson's Phosphate Buffer Solution, inhaled in five to ten minutes; 100,000 units are given on the second day and 125,000 on the third day. The immediate effects are increased expectoration and coughing due to stimulation of the cough reflex associated with liquefaction of the bronchial secretions. Administration of an antihistamine and acetylsalicylic acid will eliminate almost all side reactions (hoarseness, dyspnea, hyperpyrexia). Recovery Roolll
A postanesthesia ward has become an essential addition to a modern surgical suite. It provides close supervision of the anesthetized patient during the immediate postanesthesia period. Nurses, especially trained to recognize early signs and symptoms of undesirable complications of anesthesia and surgery, maintain continuous observation of the patient. Apparatus and supplies are concentrated in one location to meet any emergencies. The airway is properly controlled until the reflexes return. Oxygen therapy is available to combat hypoxia. Incipient shock states are recognized early and actively treated. This concentration of patients who have just completed surgery and anesthesia has permitted the training of personnel especially adept at treating any postanesthetic or postsurgical emergency. All patients who have had abdominal surgery should be brought to this ward immediately postoperatively. Adequate prophylaxis, early recognition of complications, and prompt and adequate treatment will increase the safety of the patient and decrease morbidity. CAUTIONS
1. Special care must be exercised in anesthesia for the aged to avoid wide swings in depth of anesthesia, prolonged deep anesthesia, and hypotension, and to maintain adequately high oxygenation. 2. The maintenance of adequate blood volume and nutrition, and
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Mary Karp, C. S. Vein
avoidance of circulatory embarrassment through overloading with salt and water and use of anesthetics are very important factors in reducing the mortality rate in aged patients. 3. Avoid scopolamine in the old age groups. These drugs often cause elderly patients to become confused and disoriented. 4. The rule "never give a general anesthesia until four hours have elapsed from the ingestion of food" is a poor rule. Food may remain undigested in the stomach for many hours in the anxious frightened patient; this is especially true of a patient who has been in an accident. 5. Do not give curare to a patient who has intestinal obstruction with distention. The profound immediate relaxation may produce an inundation of gastric contents with possible aspiration into the tracheobronchial tree. 6. Do not give Pentothal to the markedly hypertensive patient or to the asthmatic patient. 7. Trendelenburg position reduces the respiratory ventilation in direct proportion to its degree. Avoid steep Trendelenburg especially in cardiac and obese patients and where there is marked abdominal distention. 8. A thorough "tracheobronchial toilet" at the end of an operation and frequent position changes of the patient during the immediate postoperative period will reduce the number of respiratory complications. 9. Avoid oversedation in the postoperative period; encourage deep breathing exercises and leg activity. 10. Profound irreversible shock may not respond to intravenous fluids. Arterial transfusions and infusions of l-norepinephrine may reverse the process. 11. Avoid large regional blocks, especially spinal anesthesias, in the severely anemic patient, or when pre-existing central nervous system disease exists: 12. A large gauge needle in a vein is a life line for the patient. Do not substitute small gauge needles which clog readily. 13. Pentothal is not the ideal agent for all abdominal cases. 14. Whenever curare is administered, respirations should be assisted or controlled. 15. Check the collateral circulation of an extremity before doing an arterial transfusion. An embarrassing complication may be gangrene of a hand. Wesley Memorial Hospital 250 E. Superior Street Chicago 11, Illinois
c. S. YEIN, M.D. **
IN general, the choice of an anesthetic agent and method depends on a proper understanding of a given situation by the anesthesiologist, surgeon and, when possible, the patient. There is no substitute for an experienced team. The agent selected or the method used is of secondary importance. This is attested by the fact that a variety of agents have proved successful in the hands of one anesthesiologist or another. The major advances have not been in the discovery of new agents or techniques but rather in a fuller application of the basic sciences to the practice of anesthesiology. Of greatest importance is a thorough understanding of physiology and pharmacology of circulation and respiration, combined with clinical training. ANESTHETIC METHODS AND AGENTS
Generally speaking, abdominal surgery is performed under one or more of the following anesthetic methods and agents: 1. Regional block with secobarbital (Seconal) or thiopental (Pentothal) hypnosis 2. Gas-ether with thiopental induction and with or without a muscle relaxant 3. Thiopental, nitrous oxide and oxygen with a muscle relaxant
Ether Ether still continues to hold first place as the safest agent. It yields all depths of anesthesia with adequate relaxation for abdominal exposure and with little immediate risk to the patient. Even in small quantities it tends to stabilize a cyclopropane or Pentothal-curare anesthesia .. It has the great advantage of being a respiratory stimulant except in deep
* Assistant Professor of Surgery and Director of Anesthesia, Northwestern University Medical School, Chicago.
** Fellow in Surgery (Anesthesiology), Northwestern University Medical School, Chicago. 17
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Mary Karp, C. S. Yein
planes of anesthesia. This, plus a slow action and its 100 per cent potency, combine to make it universally popular. Our concept concerning ether has been changing gradually. In the past it has been considered a poor choice for patients with heart or lung disease. Many anesthesiologists now consider ether to be the agent of choice in such conditions. It should be the basic potent anesthetic agent, and all other anesthetic drugs should show specific advantages before being selected in preference to ether. However, one must be mindful of its disadvantages. Symptoms of shock may be exhi.bited by a patient during an operation as a result of a deep ether anesthesia. The functioning power of the pancreas is disturbed, preventing the conversion of glucose into glycogen, storage of glycogen in the liver and also interfering with the metabolism of glycogen already present there. Other disadvantages are reduced renal function, postanesthetic toxic symptoms and postanesthetic respiratory morbidity. For these reasons ether must not be used as the sole agent for producing profound abdominal anesthesia. Cyclopropane
Cyclopropane is a 100 per cent potent agent permitting fast, smooth progress throughout all stages of anesthesia. This fact alone makes its use a hazard by the untrained or partially trained administrators of anesthetic drugs. The tendency at the present time is to use cyclopropane with a combination of other drugs rather than a sole agent; that is, to produce a "balanced mixture" with ethylene, nitrous oxide, ether or curare in varying combinations as needed. Until the full significance of the effect on the heart is understood this drug should be contraindicated in those patients with cardiac disease. However, one of its first clinical users, Dr. Griffith, stated in this regard: "My own opinion, based on long clinical experience, is almost exactly the opposite-that generally speaking, cyclopropane is the anesthetic of choice for patients with serious heart disease who must undergo major surgical procedures." Pentothal Sodium
Pentothal enjoys great popularity and'widespread use because of its smooth, rapid, pleasant induction, ease of administration and minimal after-effects. Approximately 90 per cent of all abdominal cases receive Pentothal as an induction agent. It should seldom be used alone but should be combined with nitrous oxide-oxygen, local or regional anesthesia and curare. When shock is present, or hemorrhage, or extreme debility, it should be administered with extreme caution, if at all. Because it causes constriction of the bronchioles and is a respiratory depressant, it is contraindicated in those patients who have respiratory
Anesthesia for Abdominal Surgery
19
obstructions, acute pulmonary disease or asthma. The hypertensive patient takes pentothal poorly often suffering hypotensive effects. The aged and very young have difficulty in maintaining satisfactory physiological balance during the course of intravenous anesthesia. Another anesthetic agent will be preferable in these cases. Muscle Relaxants
Muscle relaxants available to the anesthetist have increased in number in recent years, so that well over a dozen different products are now in commercial use. Each one has advantages, variations in duration of action and depth of relaxation, and has disadvantages. Of special interest is the most recently introduced, succinylcholine chloride (Anectine), a short-acting curarizing agent whose action is so brief that it lends itself to administration by intravenous continuous drip. Recovery of full muscle tone and reflex activity follows within one to five minutes after the infusion is discontinued. This minute-to-minute control offers a great safety factor to curare administration, and it is predicted that this drug will become the muscle relaxant of choice for abdominal surgery. The curare drugs may be combined with all anesthetic agents, permitting smaller doses of analgesic or hypnotic drugs. They have excellent muscle-relaxing effects when combined with cyclopropane, neither increasing nor decreasing the irritability of the heart in this combination. Their use should be restricted to those administrators capable of handling the apneic patient. This group of drugs has such powerful action and is so simple to administer that the unwary and inexperienced can use it and have used it to cover up errors of judgment and technique. Large series have been compiled showing that curare is a sole or major cause of anesthesia morbidity and mortality. One wonders whether such large scale studies are statistically correct in all details or whether the results obtained may be interpreted as due to poor usage of a good drug. Curare is a useful adjunct to anesthesia; in many instances it has proved life-saving. Further investigation and research will set its true pattern of clinical application. Spinal Anesthesia
Spinal anesthesia, unlike inhalation anesthesia, does not have the universal approval of all members of the medical profession. Some reserve the method for those cases for which inhalation or local anesthesia cannot possibly be used. Others use spinal anesthesia routinely for all surgical interventions below the diaphragm. The success or failure of spinal anesthesia is directly proportional to the preanesthetic evaluation of the patient, with the intelligent selection of the patient suitable for
20
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Mary Karp, C. S. Yein
the method and with adequate preanesthetic medications. It is best to maintain most patients receiving sp:nal anesthesia for abdominal surgery in a light state of hypnosis and sedation throughout the operation by means of a slow continuous intravenous drip of 0.2 to 0.5 per cent Pentothal Sodium. This reduces the objectionable features of patient awareness, the discomfort of maintaining a restrained position for any length of time, and traction reflexes. Pontocaine hydrochloride continues to be the drug of choice in most clinics. It is usually made hyperbaric by weighting it with 10 per cent dextrose, or hypobaric with triple distilled water. The use of the continuous fractional method, utilizing the malleable spinal needle or the No.3 ureteral catheter, has increased the safety of the method and prolonged its action for any length of surgical procedure. It must be remembered that the chemotoxic effects of various spinal agents aggravate pre-existing neurospinal diseases. Sensory disturbances, cranial nerve involvement (especially the sixth), and impaired bladder and rectal functions are occasional sequelae. The "spinal headache" still continues to occur in from 2 to 15 per cent of cases, and present day methods and treatment have not prevented or cured this complication. Also more serious spinal root and cord disturbances may occur. The possibility of septic meningitis is ever present, in spite of apparently aseptic technique of administration. Neurological sequelae have been estimated at 1 in 3000 to 1 in 10,000 cases. In spite of the complications listed above, it is the consensus of most anesthesiologists that the benefits of a well conducted spinal anesthesia in selected cases, especially for lower abdominal surgery, easily counterbalance the small risk involved. Certainly it provides ideal conditions for the surgeon-a completely relaxed abdomen with contracted intestines, quiet respirations and usually reduced bleeding. Balanced Anesthesia
Balanced anesthesia is produced by the administration of small amounts of several anesthetic drugs, each with a specific function; thus avoiding large toxic doses of any individual drug alone. A few years ago, ether or chloroform was used as a sole anesthetic agent throughout the surgical procedure. Gradually the pattern of anesthesia has changed to the use of multiple anesthetic drugs, which, because of their small doses, provide a wide margin of safety to the patient while producing excellent working conditions for the surgeon. Most present day anesthetic techniques for abdominal surgery involve some combination of drugs in a balanced manner; such as nitrous oxide-oxygen, Pentothal and curare; and cyclopropane, ether and curare; nitrous oxide, cyclopropane and curare. A more complicated balanced technique includes the use of secobarbital, meperidine hydrochloride (Demerol), Pentothal, curare and nitrous oxide. In such combinations the anesthesiologist must deter-
Anesthesia for Abdominal Surgery
21
mine, as the anesthesia progresses, if there is need for hypnosis, analgesia, reduction of metabolism, depression of reflexes or relaxation of musculature. Endotracheal Intubation
Endotracheal intubation is of great value in abdominal anesthesia. It is an excellent means of maintaining an adequate airway for the patient, preventing the entrance of vomitus or blood into the lung and permitting suctioning of the tracheobronchial tree. It provides means of artificial pulmonary ventilation to augment depressed respiration or to control respirations completely. By its means, the respiratory system can be separated from the gastrointestinal tract, thus avoiding distention of the stomach from gaseous agents. It promotes quiet breathing and helps to minimize the amount of anesthetic agent required. For many anesthesiologists the cuffed endotracheal tube has become a routine airway in anesthesia for upper abdominal surgery. Assisted or Controlled Respiration
Assisted or controlled respiration has been widely used in operations of the upper abdomen and to a lesser degree of the lower abdomen. It has been shown that anesthesia deep enough to produce relaxation of abdominal muscles causes various degrees of respiratory depression, either due to direct depression of the respiratory center or to paresis of the intercostal muscles. The use of assisted or controlled respiration permits the anesthesiologist to use those potent anesthetics, depressant drugs and muscular rela:l\ant agents which provide sufficient relaxation for abdominal surgery, without interfering with adequate ventilation. When the surgical procedure requires a quiet respiration, as in abdominal operations, assisted or controlled respirations can be valuable. Whenever curare is used, the assisted respiration technique should be routinely applied. It will also spare the patient the added effort of breathing against the weight of abdominal viscera, surgical packs, and tired assistants against the diaphragm. SUPPORTIVE PROCEDURES
Anesthesiologists have been aided by certain modern procedures in their attempts to attain the ideal-safety and comfort to the patient, a relaxed quiet abdomen with little bleeding and speedy uneventful recovery. I-Norepinephrine
Until the advent of l-norepinephrine bitartrate, epinephrine, d-desoxyephedrine and similar drugs were the vasodepressors most commonly
22
Nlary Karp, C. S. Yein
used by the anesthetist to combat hypotension during regional analgesia and other shock states. A study of their physiological action reveals that their pressor activity is brought about mainly by an increase in cardiac output. l-Norepinephrine (Arterenol, Levophed) though synthesized by Stoltz and Flacher in 1904, was introduced into clinical use in 1949 and 1950. It is probably the most powerful over-all vasoconstrictor drug available to the anesthesiologist. It is the physiological transmitter to most adrenergic nerves which are responsible for the control of the blood pressure; therefore, it is a suitable drug for combating hypotensive circulatory states due to a lowering of peripheral resistance. It causes no, or very little, increase in minute volume of the heart and probably some vasodilation of the coronaries. The pressor effect is not attended by increased heart rate, cardiac output or central nervous system stimulation. Its toxicity is eight times less than that of epinephrine. It produces a bradycardia due to vagal reflexes from the carotid sinus or ,the aortic arch, which is prevented by atropine. In the early phases of shock there is an over-all increase in vascular tonus which becomes progressively impaired until in the last or irreversible phase there is loss of small vessel tone and a pooling of blood. In advanced shock, fluid replacements are of no immediate benefit, and only a drug like norepinephrine may reverse this condition by increasing resistance through vasoconstriction. This drug has distinct value in sustaining the blood pressure of severe hypertensive patients, or patients with diseases of the coronary arteries. In these patients, hypotension during surgery may cause cerebral thrombosis or myocardial ischemia. Another use is to counteract the collapse under spinal anesthesia, where there has been no blood loss, but circulatory collapse has occurred with reduced cardiac output and lowered peripheral resistance. In severe sudden hemorrhage during surgery, norepinephrine will aid the compensatory mechanisms to maintain vasoconstriction of arterioles; thus it may be a life-saving bridging measure until fluid replacements are adequate. It will increase the blood pressure to normal rates following the use of hypotensive producing drugs such as pentomethonium and hexamethonium compounds. The duration of action of norepinephrine is very short; for this reason it can be readily controlled. It is administered in the following manner; 4 mg. of the drug are added to 1 liter of diluent (saline or dextrose in water) to make a strength of 4 micrograms per cubic centimeter. An infusion is started at the rate of 40 to 60 drops per minute; blood pressure readings are then checked at one to two minute intervals until the desired blood pressure is reached. The rate of flow is then reduced, usually to 6 to 10 drops per minute. This is sufficient to sustain the level desired in most cases. As soon as possible the drug is discontinued. Observation is the only satisfactory guide to correct dosage.
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A word of caution: several cases of gangrene of the superficial structures of the extremities have been reported. These are due to extravasation of the drug, or to venospasm from the powerful action of the vasoconstrict ant itself. To avoid this complication the intravenous needle should be well cannulated, the site of puncture should be the veins of the muscular regions of the arm and leg instead of the hand or foot, and the patient should be weaned from norepinephrine as soon as his condition will permit. Then warm moist packs to the extremities and intravenous procaine (0.1 per cent) may increase the circulation to the extremities sufficiently to counteract the initial ischemia of the tissues. Arterial Transfusion
One of the serious complications resulting in death during abdominal surgery is acute massive hemorrhage due to accidental rupture of the large blood vessels. Arterial transfusion of whole blood may be a lifesaving procedure under these circumstances. The indications during abdominal surgery for arterial transfusion are not many: its use is limited to specific situations such as profound shock where there is loss of small vessel tone and pooling of blood. Here intravenous transfusions will be fruitless. Another indication for the use of this technique is in preparation of the patient undergoing emergency operation for massive hemorrhage from the upper gastrointestinal tract. Though there is some question conceming the underlying action and effect of arterial transfusion, clinicians throughout the country have seen its dramatic effects. Equipment should be kept sterilized and available for emergency use. Gangrene of the extremity distal to the arterial puncture has been reported and this complication should be borne in mind whenever the use of the method is contemplated. Hypotensive Technique
The prevention of quantitatively significant bleeding in the operative field can be controlled by many ways: by posture, by profound general anesthesia, by arteriotomy, by nerve block and by means of methonium compounds and other blocking agents. When bleeding is controlled, the work of the surgeon is facilitated and operating time is shortened. The need for blood transfusions with the accompanying risk is reduced to a minimum. The use of various ganglionic blocking drugs and methods to induce a hypotensive state with a bloodless field was introduced into anesthesia in Great Britain. Its value and safety has been investigated extensively. "Controlled hypotension" demands an adequate preoperative blood volume, the immediate replacement of all blood lost, an absolutely patent airway and complete oxygenation, and provisions for expert and meticulous postoperative care. It should never be employed
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Mary Karp, C. S. Yein
in the absence of a specific or urgent indication nor for the convenience of surgery. It must never be employed by the unwary, or by the unskilled. It has questionable value in intra-abdominal surgery. In fact, the upper abdominal and pelvic sites are the most difficult to keep bloodless. In some of the extensive radical dissections this technique may be of value. A new drug, a thiophanium derivative (Arfonad), has been introduced which has the advantages of short action and controllability. It appears to be the drug of choice when this technique is indicated. The number of complications associated with this technique indicates that it should be used with great caution. Blocking Agents of Long Duration
The physician has long been in quest of a local anesthetic agent with low toxicity and prolonged action. Such a drug injected into the intercostal nerves or paravertebrally would reduce the postoperative pain of abdominal surgery, permitting unhampered ventilation, free body activity and reduced postoperative hospitalization. Several drugs have been introduced for this purpose. By far the most successful agent, judging from clinical reports, is Efocaine, a solution of procaine 1 per cent; procaine hydrochloride 0.25 per cent; and butyl-p-aminobenzoate 5 per cent in a solvent polyethyleneglycol-300, 2 per cent; propyleneglycol 78 per cent and water. However, in recent months clinical evidence from case reports seem to indicate that Efocaine has caused perirectal sloughs, unilateral anhydrosis, severe neuralgia, postinjection neuritis and pain, atonic bladder and long-lasting and probably permanent motor paralysis of the lower extremities. It would appear, from the increasing number of reports of complications from the use of this drug, that it should be used with extreme caution if at all. Inhalation of Wetting Agents and EnzYIlles Postoperatively
General anesthesia for abdominal surgery may be followed postoperatively by prolonged periods of respiratory depression, loss of body tone, and inability to expectorate lung secretions because of pain and weakness. The chief damage of retained secretions is airway obstruction. This may result in atelectasis, emphysema, or infection distal to the obstruction. Some of these sequelae require prolonged medical care and may be a cause of disability or limited activity for long periods of time. Hence, the importance of maintaining a moist atmosphere in the tracheobronchial tree and liquefying and removing sections before the occurrence of airway obstruction and the potential complications. Of the number of wetting agents and enzymes tested, two drugs are used most frequently at the present time to liquefy lung secretions: a new detergent, Alevaire, and a trypsin enzyme, Tryptar. Alevaire is an aqueous solution of a new synthetic detergent (a mem-
Anesthesia for Abdominal Surgery
25
ber of the alkylaryl polyther alcohols) in combination with sodium bicarbonate 2 per cent and glycerin 5 per cent. It is particularly suited for medical use because of its activity in lowering surface tension, and its chemical inertness. Its thinning effect on highly viscid sputum is constant and dependable and without toxicity. It is indicated for the treatment of diseases of the lungs accompanied or complicated by the presence of excessive or thickened bronchopulmonary secretions. It is administered by aerosol nebulizer, mask or tent, its vehicle being air or oxygen. Up to 500 cc. can be nebulized per day without producing toxic symptoms. The length of treatment varies, usually from 24 to 72 hours. Trypsin, a proteolytic enzyme obtained from the pancreas of all animals, also has the property of thinning and digesting tenacious secretions within the tracheobronchial tree. It is administered by means of nebulizer or mask, with oxygen as a vehicle. The initial adult dose is 75,000 units of trypsin in Sorenson's Phosphate Buffer Solution, inhaled in five to ten minutes; 100,000 units are given on the second day and 125,000 on the third day. The immediate effects are increased expectoration and coughing due to stimulation of the cough reflex associated with liquefaction of the bronchial secretions. Administration of an antihistamine and acetylsalicylic acid will eliminate almost all side reactions (hoarseness, dyspnea, hyperpyrexia). Recovery Roolll
A postanesthesia ward has become an essential addition to a modern surgical suite. It provides close supervision of the anesthetized patient during the immediate postanesthesia period. Nurses, especially trained to recognize early signs and symptoms of undesirable complications of anesthesia and surgery, maintain continuous observation of the patient. Apparatus and supplies are concentrated in one location to meet any emergencies. The airway is properly controlled until the reflexes return. Oxygen therapy is available to combat hypoxia. Incipient shock states are recognized early and actively treated. This concentration of patients who have just completed surgery and anesthesia has permitted the training of personnel especially adept at treating any postanesthetic or postsurgical emergency. All patients who have had abdominal surgery should be brought to this ward immediately postoperatively. Adequate prophylaxis, early recognition of complications, and prompt and adequate treatment will increase the safety of the patient and decrease morbidity. CAUTIONS
1. Special care must be exercised in anesthesia for the aged to avoid wide swings in depth of anesthesia, prolonged deep anesthesia, and hypotension, and to maintain adequately high oxygenation. 2. The maintenance of adequate blood volume and nutrition, and
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Mary Karp, C. S. Vein
avoidance of circulatory embarrassment through overloading with salt and water and use of anesthetics are very important factors in reducing the mortality rate in aged patients. 3. Avoid scopolamine in the old age groups. These drugs often cause elderly patients to become confused and disoriented. 4. The rule "never give a general anesthesia until four hours have elapsed from the ingestion of food" is a poor rule. Food may remain undigested in the stomach for many hours in the anxious frightened patient; this is especially true of a patient who has been in an accident. 5. Do not give curare to a patient who has intestinal obstruction with distention. The profound immediate relaxation may produce an inundation of gastric contents with possible aspiration into the tracheobronchial tree. 6. Do not give Pentothal to the markedly hypertensive patient or to the asthmatic patient. 7. Trendelenburg position reduces the respiratory ventilation in direct proportion to its degree. Avoid steep Trendelenburg especially in cardiac and obese patients and where there is marked abdominal distention. 8. A thorough "tracheobronchial toilet" at the end of an operation and frequent position changes of the patient during the immediate postoperative period will reduce the number of respiratory complications. 9. Avoid oversedation in the postoperative period; encourage deep breathing exercises and leg activity. 10. Profound irreversible shock may not respond to intravenous fluids. Arterial transfusions and infusions of l-norepinephrine may reverse the process. 11. Avoid large regional blocks, especially spinal anesthesias, in the severely anemic patient, or when pre-existing central nervous system disease exists: 12. A large gauge needle in a vein is a life line for the patient. Do not substitute small gauge needles which clog readily. 13. Pentothal is not the ideal agent for all abdominal cases. 14. Whenever curare is administered, respirations should be assisted or controlled. 15. Check the collateral circulation of an extremity before doing an arterial transfusion. An embarrassing complication may be gangrene of a hand. Wesley Memorial Hospital 250 E. Superior Street Chicago 11, Illinois