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Management of Diabetes in the Surgical Patient
Symposium on Diabetes Mellitus
Management of Diabetes in the Surgical Patient Jurgen Steinke, MD.*
Patients with diabetes mellitus may be affected by any surgical disease and on rare occasion may even be the object of spectacular surgical triumphs; the first successful heart transplant was performed in a diabetic. In addition, in the diabetic population-at-Iarge conditions requiring surgery, such as peripheral vascular disease, gallbladder disease, and cancer of the pancreas, are more frequent. As diabetes is one of the commonest metabolic disorders, from time to time every surgeon and anesthetist will be confronted with diabetic patients. Although at the present time the over-all surgical mortality of diabetic patients is approximately that of the general population, many diabetic patients present a higher surgical risk because of premature arteriosclerosis with consequent cardiac, renal, and cerebral impairment. In keeping this in mind, it is useful to add the patient's duration of diabetes in years to his chronologic age to assess his "functional" age. For example, a man with a chronologic age of 45 and 15 years of diabetes may have a vascular system corresponding to that of a 60 year old man. It is obvious that a 60 year old man will require more careful preoperative evaluation and intraoperative monitoring than a 45 year old patient. Recently several papers have dealt with the diabetic patient facing surgery.4, 6, 9,10,11 Not only the diabetic, but any patient undergoing surgery, is exposed to a triple stress: the anxiety to surgery, the metabolic effect of anesthesia, and the surgical procedure per se. In a diabetic patient, the stressful situation may lead to further metabolic decompensation. The hormonal response to stress is mediated mainly by increased secretion of epinephrine and glucocorticoids. It manifests itself by a rise in blood sugar and free fatty acids and a fall in circulating insulin. Epinephrine From the Diabetic Unit, Peter Bent Brigham Hospital, and the Joslin Research Laboratory, Department of Medicine, Harvard Medical School, Boston, Massachusetts "Assistant Professor of Medicine; Senior Associate, Peter Bent Brigham Hospital Supported in part by a Diabetes Training Grant (AM05077) from the National Institutes of Health Medical Clinics of North America- VoL 55, No. 4, July 1971
939
940
JURGEN STEINKE
produces hyperglycemia by stimulating breakdown of liver glycogen, decreasing glucose uptake by muscle and directly inhibiting pancreatic insulin release. The glucocorticoids exert their diabetogenic action by increasing hepatic gluconeogenesis from proteins, decreasing glucose uptake by adipose tissue and possibly by stimulating the formation of a still ill-defined circulating insulin antagonist. All these mechanisms lead to need for additional endogenous or exogenous insulin. In addition, an anesthetic itself may affect carbohydrate metabolism to some extent. Studies in nondiabetic subjects have demonstrated that nitrous oxide, thiopental, trichlorethylene, cyclopropane, and halothane have the least effect on blood glucose, whereas chloroform and ether have the most. I. 2. :1, 5, 7 In practice, however, the observed rise in blood sugar consists only of 10 to 50 mg. per 100 ml.; therefore, the choice of anesthesia should not be influenced by the presence of diabetes. The stress induced by the surgical procedure will depend directly on the magnitude and duration of the procedure. According to recent studies, intra-abdominal manipulation represents the most stressful situation. 3 It is evident, therefore, that many factors will influence the metabolic reactions in a diabetic undergoing surgery, and thus it would be rather futile to describe the management of a theoretical patient. The approach will have to vary with the surgical procedure contemplated and will have to be adjusted to the severity of the patient's diabetic condition. For practical purposes, the latter can be assessed from the patient's previous treatment, i.e., whether it was only dietary, included diet and oral hypoglycemic agents, or required insulin. The following situations will consequently be discussed; the known diabetic undergoing either a minor or a major procedure (Table 1); the previously unknown diabetic whose disease is diagnosed preoperatively and finally emergency procedures in a diabetic patient. Regardless of the type of diabetes the patient exhibits and the nature of the operation to be performed, every diabetic patient undergoing surgery presents a challenge: the danger of ketoacidosis or nonketotic hyperosmolar coma if the disease is undertreated, or hypo glycemia if it is overtreated.
THE KNOWN DIABETIC PATIENT Regardless of the severity of their disease, most diabetic patients scheduled to undergo elective surgery should be admitted at least 1 and
Table 1.
Management of Diabetes on the Day of Surgery PREVIOUS DIABETIC TREATMENT
SURGICAL
Oral Hypoglycemic Agent
PROCEDURE
Diet Only
Insulin
Minor
Observe
Withhold until after procedure
Withhold until after procedure
Major
Observe
Change to insulin (10-20 units NPH)
One third of total dose preoperatively; one third postoperatively: crystalline insulin only if needed
DIABETES IN THE SURGICAL PATIENT
941
preferably 2 days in advance to assess their diabetic state, including their renal threshold for glucose, and to permit adjustments if needed. On the day of surgery every diabetic patient should have (1) a fasting blood glucose determination done immediately as a base line, and (2) instead of breakfast, a slow intravenous drip of 1000 ml. of 5 per cent dextrose in water should be started, as lack of carbohydrate intake will lead to starvation ketosis. A total intake of 50 to 75 gm. of carbohydrate per day will prevent it. In the postoperative period, later in the afternoon, a second blood test is done. For rapid but only approximate assessment, celulose strips containing glucose oxidase and an indicator system (Dextrostix) may be used. In addition, urine should be tested for glucose and acetone, at intervals of 4 to 6 hours, but a patient should never be catheterized solely for this purpose. The diabetic patient who requires only diet to control his hyperglycemia ("chemical" diabetes) needs only surveillance, as outlined above. If the diabetic state is deteriorating owing to the stress of the underlying disease or as a result of anxiety, anesthesia, or surgery, insulin may be needed temporarily in the postoperative period. The amount of insulin required can be estimated by the "sliding scale" technique; however, in general a single daily injection of 10 to 20 U of isophane (NPH) or lente insulin will suffice to reduce the blood glucose to below 200 mg. per 100 ml. The fear that once a patient takes insulin he must always take insulin is not borne out by experience. Once the patient has recovered, insulin can be often discontinued. This is particularly true if surgery removed the reason for diabetic decompensation (an abscess or an inflamed gallbladder). With respect to the use of insulin by the sliding scale technique,!! it is common practice to administer regular (clear-soluble-crystalline) insulin according to urine test results. A typical order would read as follows: test the urine every four hours and give 15 U of regular insulin subcutaneously for a 4+ urine specimen, 10 U for a 3+ specimen, 5 U for a 2+ specimen, and no insulin for a 1+, trace, or negative specimen. This order needs to be adjusted individually - that is, it may be reduced for an elderly, frail patient or increased for an obese patient. The insulin should be given subcutaneously and not by means of the infusion bottle, for insulin sticks to glass, and the patient may thus receive less insulin than was ordered. This sliding-scale technique is popular and appears to be scientifically sound, since the more sugar is spilled in the urine, the more insulin will be injected. The drawbacks of the technique are three-fold. First of all, it requires frequent collection of urine specimens; second, it assumes a normal renal threshold. However, with age the renal threshold frequently increases, and, since most diabetic patients are in the older age group, it is not uncommon to find a renal threshold of 200 or occasionally even 300 mg. per 100 ml. before sugar will appear in the urine. As a result, the patient will be undertreated. Finally, the insulin treatment is always several hours behind the actual blood glucose; thus the slidingscale technique does not anticipate the need for insulin but rather prescribes it retrospectively. Therefore, the author prefers a prophylactic small dose of NPH insulin, supplemented if necessary by regular insulin.
942
JURGEN STEINKE
The diabetic patient on an oral hypoglycemic agent may be handled in one of two ways. If the surgery is minor, the tablets are omitted preoperatively and are given before supper if of the short acting type (tolbutamide), or withheld until the next day if of the long-acting type (chlorpropamide).4 For example, a 62 year old diabetic man with a gangrenous toe could be managed in this way: (1) fasting blood glucose, (2) a slow infusion of 1000 ml. of 5 per cent dextrose in water preoperatively, during surgery, and in the immediate postoperative period, (3) spinal anesthesia for the toe amputation, followed in the later afternoon by 2 tablets of tolbutamide and a light supper. The alternative way of handling the patient who is taking an oral agent is to switch him temporarily to insulin. This is almost always indicated if the procedure is a major one, if general anesthesia is indicated, if the nature of surgery requires intravenous feeding for several days, or if the diabetes is poorly controlled. Insulin can be administered by the sliding scale technique (see above) or in the form of small amounts of intermediate insulin such as 10 to 20 units of NPH or lente insulin. This regimen can be continued on a once-a-day basis until oral intake can be resumed. Such small amounts of insulin are usually well tolerated and will prevent any excessive hyperglycemia. Although an article has recently appeared in the German literature proposing the intravenous administration of tolbutamide for these patients in the postoperative period,s insulin is preferred in this country. For the diabetic patient on insulin, one's plan will depend to a large extent on the type of surgical procedure and the hour of surgery. Such operations should be scheduled early in the morning so that the period of fasting is not prolonged. If the procedure is minor and is scheduled early, and if oral intake can be resumed that evening, insulin can be withheld until the patient is in the recovery room, at which time two thirds of his total dose is given. If a major surgical procedure is planned, it is best to reduce the total insulin dose by one third and to give one third before and one third after operation, to be supplemented in the postoperative period with regular insulin on a sliding scale if necessary. In this way, both hypo glycemia and severe hyperglycemia can be avoided. As an example, a 48 year old patient takes 15 U of regular insulin and 35 U of NPH insulin every morning. On the day of surgery the fasting bl00d glucose is determined; instead of breakfast a slow intravenous infusion with 5 per cent dextrose in saline or water is started, and 5 U of regular and 12 U of NPH insulin are given. In the recovery room in the afternoon, a second blood sugar is obtained, and he receives an additional 5 U of regular and 12 U of NPH insulin. If the blood sugar level is reported as above 200 mg. per 100 ml., or if a urine specimen shows a 4+ test for sugar, additional regular insulin will be given. In practice, however, this will rarely be necessary. If on the next day intravenous fluids are continued on a 24 hour basis, insulin can again be administered, one third in the morning and one third in the afternoon, adjustments being made on the basis of fasting and 3 P.M. blood sugars. Once the infusions are reduced or the patient is returned to oral feedings, insulin can be resumed in a single injection.
DIABETES IN THE SURGICAL PATIENT
943
There are physicians who fear the occurrence of hypo glycemia on the day of surgery because little or no food is taken on that day, and who therefore prefer to withhold all insulin until the postoperative period, when it is administered only by the sliding-scale technique. However, experience has shown that the combination of glucose given slowly intravenously and the metabolic effects of anxiety, surgery, and anesthesia will counterbalance the effect of preoperatively given insulin to a surprising degree. In actual practice hypo glycemia is uncommon. If hypoglycemia does occur, one of three conditions is usually responsible: (1) The patient has been on an unrestricted diet at home and therefore has been taking a large amount of insulin. Under controlled hospital conditions his caloric intake will be restricted, and if insulin is not markedly reduced, hypoglycemia will ensue during or after surgery. (2) In a known diabetic, hypophysectomy or removal of the adrenal glands will suddenly induce a state of marked insulin sensitivity and, if not anticipated, insulin will produce severe hypoglycemia. For these conditions, insulin should not be routinely prescribed in the postoperative period. If needed, it must be administered very cautiously in small doses. Ten units of regular insulin in these circumstances may cause severe hypo glycemia, resulting in convulsions. (3) The delivery of a pregnant diabetic patient. Almost all pregnant diabetic patients will require insulin, usually in rather large amounts, owing to insulin resistance caused mainly by hormonal placental factors such as corticosteroids and placental lactogen. Once the baby is delivered, either vaginally or by cesarean section, these factors disappear, and the patient will return suddenly to her prepregnancy state of insulin sensitivity. Therefore, hypo glycemia on the day of delivery is extremely common. It is best prevented by omitting all insulin on the scheduled day of delivery.
THE UNDIAGNOSED DIABETIC PATIENT It has been estimated by carefully carried out population surveys that there are as many undiagnosed as known diabetic subjects. For the United States that means the presence of some two million undiagnosed cases, most of them representing individuals above the age of 40. This has been borne out by the author's experience, in which approximately one third of diabetic patients scheduled to undergo surgery are newly diagnosed diabetic patients. It is surprising how well most of these people adjust to chronic hyperglycemia. Patients with blood glucose levels in the range of 200 to 300 mg. per 100 ml. may continue their daily chores, attributing nocturia to old age, weight loss to self-imposed diets for obesity, and fatigue to lack of a vacation. These patients may appear well compensated; however, under the stress of surgery, ketoacidosis may develop swiftly, with resultant dehydration. and electrolyte loss. Fortunately, this almost never happens, since it'is now a universal routine to test for diabetes on admission to any hospital. If glucosuria or hyperglycemia is detected, surgery should be postponed until the diabetic state can be evaluated
944
JURGEN STEINKE
by further urine tests, by blood tests taken 1 or 2 hours after meals, or by an oral glucose tolerance test. Only when the severity or mildness of the diabetes has been established and proper treatment has been initiated should one proceed with surgery. On the other hand, the presence of sugar in the urine does not always indicate diabetes mellitus; it may mean renal glucosuria which of course does not require any medical treatment. These patients, who under normal conditions lose variable amounts of sugar and therefore calories in the urine, easily develop starvation ketosis if they are fasted. It is not uncommon therefore that they will exhibit glycosuria and acetonuria, and thus become undistinguishable from true diabetics if only their urinary findings are taken into account.
UNCONTROLLED DIABETES AND EMERGENCY SURGERY Most diabetic patients are in a reasonable state of metabolic control, and emergency surgery can be performed immediately or within a few hours. A brief diabetic history including duration of the disease and previous treatment, a urine test for sugar, acetone and protein, a blood sugar determination sent to the laboratory and simultaneously tested with Dextrostix, a plasma acetone test done at the bedside, and a blood sample sent to the laboratory for bicarbonate, electrolyte, and urea nitrogen de terminations suffice for a rapid diabetic evaluation. If the diabetes is decompensated because it was not known or the underlying disease such as a severe infection intensified it, treatment is initiated immediately with intravenous fluids and insulin.'" The choice of fluid will vary from patient to patient. If he is severely dehydrated and has good cardiac and renal function, normal saline can be administered; 4 to 6 liters are usually required. If the cardiac reserve is borderline or poor, half normal saline is indicated. If the patient has nonketotic hyperosmolar coma with grossly elevated serum sodium, despite hyperglycemia, 5 per cent dextrose in water is probably better than saline. If there is any indication that lactic acidosis may be present in combination with ketoacidosis, as indicated by only moderately elevated blood sugar and serum ketones, but grossly depressed serum bicarbonate level, then liberal use of bicarbonate is justified. The amount of insulin will vary with the blood sugar, the timing of the last insulin dose, if any, and the duration and magnitude of the surgical procedure. None may be required until the postoperative period, or if the blood sugar is elevated, the usual daily insulin dose may be repeated preoperatively. If ketoacidosis is present, 50 units may have to be given by intravenous push and 50 subcutaneously, to be repeated every 2 hours if needed, as indicated by laboratory tests. It is important to realize that diabetic ketoacidosis per se may mimic an abdominal emergency such as an acute appendicitis ("pseudoappendicitis" of early diabetic ketoacidosis). Failure to recognize this possibility may be fatal. For example, a 16 year old previously healthy high school student is seen at the emergency ward with acute abdominal pain and vomiting. His white-cell count is 18,000
DIABETES IN THE SURGICAL PATIENT
945
per CU. mm; his urine gives a 4+ test for sugar, with a large amount of acetone. An immediate blood glucose is reported as 450 mg. per 100 ml., bicarbonate is 11 mEq. per liter. He is seen by both an internist and a surgeon. He is treated medically with a total of 75 units of insulin and 4 liters of normal saline intravenously and responds well. However, an identical clinical picture in another patient could have been due to acute appendicitis which led to the decompensation of diabetes. It is often impossible to make the correct differential diagnosis at the beginning; thus it is of utmost importance that such difficult situations be approached by a combined medical-surgical team.
REFERENCES 1. Allison, S. P., Tomlin, P. J., and Chamberlain, M. J.: Some effects of anesthesia and surgery on carbohydrate and fat metabolism. Brit. J. Anaesth., 41 :588-93, 1969. 2. Bunker, J. P., and Vandam, L. D.: Effects of anesthesia on metabolism and cellular function. Pharmacol. Rev., 17:183-263,1965. 3. Clark, R. S.: The hyperglycaemic response to different types of surgery and anaesthesia. Brit. J. Anaesth., 42:45-53, 1970. 4. Galloway, J. A., and Shuman, C. R.: Profile, specific methods of management and response of diabetic patients to anesthesia and surgery. Int. Anesth. Clin., 5:437-466, 1967. 5. Greene, N. M.: Carbohydrate metabolism and anesthesia. Int. Anesth. Clin., 5:411-426, 1967. 6. Marble, A., and Steinke, J.: Physiology and pharmacology in diabetes mellitus: Guiding the diabetic patient through the surgical period. Anesthesiol., 24:442, 1963. 7. Schweizer, D., and Howland, W. S.: Some metabolic changes associated with anesthesia and operation. Surg. Clin. N. Amer., 49:223-31,1969. 8. Schmitt, H., Liebermeister, H., LoSardo, G., and Daweke, H.: Treatment of maturity-onset diabetics with intravenous tolbutamide during surgery. Diabetologia, 4:307-308, 1968. 9. Shipp, J. C.: Diabetes mellitus, anesthesia, and surgery. Int. Anesth. Clin., 6:189-209, 1968. 10. Stanley, V. F., Giesecke, A. H., Jr., and Seltzer, H. S.: Anesthesia for the diabetic patient. Clin. Anesth.,3:264-74, 1968. 11. Steinke, J.: Management of diabetes mellitus and surgery. New Eng. J. Med., 282:14721474,1970. 12. Steinke, J., and Thorn, G. W.: Diabetes mellitus. In Harrison, T. R., ed.: Principles of Internal Medicine. New York, McGraw Hill Book Co., New York, 6th ed., 1970. 170 Pilgrim Road Boston, Massachusetts 02215
Management of Diabetes in the Surgical Patient Jurgen Steinke, MD.*
Patients with diabetes mellitus may be affected by any surgical disease and on rare occasion may even be the object of spectacular surgical triumphs; the first successful heart transplant was performed in a diabetic. In addition, in the diabetic population-at-Iarge conditions requiring surgery, such as peripheral vascular disease, gallbladder disease, and cancer of the pancreas, are more frequent. As diabetes is one of the commonest metabolic disorders, from time to time every surgeon and anesthetist will be confronted with diabetic patients. Although at the present time the over-all surgical mortality of diabetic patients is approximately that of the general population, many diabetic patients present a higher surgical risk because of premature arteriosclerosis with consequent cardiac, renal, and cerebral impairment. In keeping this in mind, it is useful to add the patient's duration of diabetes in years to his chronologic age to assess his "functional" age. For example, a man with a chronologic age of 45 and 15 years of diabetes may have a vascular system corresponding to that of a 60 year old man. It is obvious that a 60 year old man will require more careful preoperative evaluation and intraoperative monitoring than a 45 year old patient. Recently several papers have dealt with the diabetic patient facing surgery.4, 6, 9,10,11 Not only the diabetic, but any patient undergoing surgery, is exposed to a triple stress: the anxiety to surgery, the metabolic effect of anesthesia, and the surgical procedure per se. In a diabetic patient, the stressful situation may lead to further metabolic decompensation. The hormonal response to stress is mediated mainly by increased secretion of epinephrine and glucocorticoids. It manifests itself by a rise in blood sugar and free fatty acids and a fall in circulating insulin. Epinephrine From the Diabetic Unit, Peter Bent Brigham Hospital, and the Joslin Research Laboratory, Department of Medicine, Harvard Medical School, Boston, Massachusetts "Assistant Professor of Medicine; Senior Associate, Peter Bent Brigham Hospital Supported in part by a Diabetes Training Grant (AM05077) from the National Institutes of Health Medical Clinics of North America- VoL 55, No. 4, July 1971
939
940
JURGEN STEINKE
produces hyperglycemia by stimulating breakdown of liver glycogen, decreasing glucose uptake by muscle and directly inhibiting pancreatic insulin release. The glucocorticoids exert their diabetogenic action by increasing hepatic gluconeogenesis from proteins, decreasing glucose uptake by adipose tissue and possibly by stimulating the formation of a still ill-defined circulating insulin antagonist. All these mechanisms lead to need for additional endogenous or exogenous insulin. In addition, an anesthetic itself may affect carbohydrate metabolism to some extent. Studies in nondiabetic subjects have demonstrated that nitrous oxide, thiopental, trichlorethylene, cyclopropane, and halothane have the least effect on blood glucose, whereas chloroform and ether have the most. I. 2. :1, 5, 7 In practice, however, the observed rise in blood sugar consists only of 10 to 50 mg. per 100 ml.; therefore, the choice of anesthesia should not be influenced by the presence of diabetes. The stress induced by the surgical procedure will depend directly on the magnitude and duration of the procedure. According to recent studies, intra-abdominal manipulation represents the most stressful situation. 3 It is evident, therefore, that many factors will influence the metabolic reactions in a diabetic undergoing surgery, and thus it would be rather futile to describe the management of a theoretical patient. The approach will have to vary with the surgical procedure contemplated and will have to be adjusted to the severity of the patient's diabetic condition. For practical purposes, the latter can be assessed from the patient's previous treatment, i.e., whether it was only dietary, included diet and oral hypoglycemic agents, or required insulin. The following situations will consequently be discussed; the known diabetic undergoing either a minor or a major procedure (Table 1); the previously unknown diabetic whose disease is diagnosed preoperatively and finally emergency procedures in a diabetic patient. Regardless of the type of diabetes the patient exhibits and the nature of the operation to be performed, every diabetic patient undergoing surgery presents a challenge: the danger of ketoacidosis or nonketotic hyperosmolar coma if the disease is undertreated, or hypo glycemia if it is overtreated.
THE KNOWN DIABETIC PATIENT Regardless of the severity of their disease, most diabetic patients scheduled to undergo elective surgery should be admitted at least 1 and
Table 1.
Management of Diabetes on the Day of Surgery PREVIOUS DIABETIC TREATMENT
SURGICAL
Oral Hypoglycemic Agent
PROCEDURE
Diet Only
Insulin
Minor
Observe
Withhold until after procedure
Withhold until after procedure
Major
Observe
Change to insulin (10-20 units NPH)
One third of total dose preoperatively; one third postoperatively: crystalline insulin only if needed
DIABETES IN THE SURGICAL PATIENT
941
preferably 2 days in advance to assess their diabetic state, including their renal threshold for glucose, and to permit adjustments if needed. On the day of surgery every diabetic patient should have (1) a fasting blood glucose determination done immediately as a base line, and (2) instead of breakfast, a slow intravenous drip of 1000 ml. of 5 per cent dextrose in water should be started, as lack of carbohydrate intake will lead to starvation ketosis. A total intake of 50 to 75 gm. of carbohydrate per day will prevent it. In the postoperative period, later in the afternoon, a second blood test is done. For rapid but only approximate assessment, celulose strips containing glucose oxidase and an indicator system (Dextrostix) may be used. In addition, urine should be tested for glucose and acetone, at intervals of 4 to 6 hours, but a patient should never be catheterized solely for this purpose. The diabetic patient who requires only diet to control his hyperglycemia ("chemical" diabetes) needs only surveillance, as outlined above. If the diabetic state is deteriorating owing to the stress of the underlying disease or as a result of anxiety, anesthesia, or surgery, insulin may be needed temporarily in the postoperative period. The amount of insulin required can be estimated by the "sliding scale" technique; however, in general a single daily injection of 10 to 20 U of isophane (NPH) or lente insulin will suffice to reduce the blood glucose to below 200 mg. per 100 ml. The fear that once a patient takes insulin he must always take insulin is not borne out by experience. Once the patient has recovered, insulin can be often discontinued. This is particularly true if surgery removed the reason for diabetic decompensation (an abscess or an inflamed gallbladder). With respect to the use of insulin by the sliding scale technique,!! it is common practice to administer regular (clear-soluble-crystalline) insulin according to urine test results. A typical order would read as follows: test the urine every four hours and give 15 U of regular insulin subcutaneously for a 4+ urine specimen, 10 U for a 3+ specimen, 5 U for a 2+ specimen, and no insulin for a 1+, trace, or negative specimen. This order needs to be adjusted individually - that is, it may be reduced for an elderly, frail patient or increased for an obese patient. The insulin should be given subcutaneously and not by means of the infusion bottle, for insulin sticks to glass, and the patient may thus receive less insulin than was ordered. This sliding-scale technique is popular and appears to be scientifically sound, since the more sugar is spilled in the urine, the more insulin will be injected. The drawbacks of the technique are three-fold. First of all, it requires frequent collection of urine specimens; second, it assumes a normal renal threshold. However, with age the renal threshold frequently increases, and, since most diabetic patients are in the older age group, it is not uncommon to find a renal threshold of 200 or occasionally even 300 mg. per 100 ml. before sugar will appear in the urine. As a result, the patient will be undertreated. Finally, the insulin treatment is always several hours behind the actual blood glucose; thus the slidingscale technique does not anticipate the need for insulin but rather prescribes it retrospectively. Therefore, the author prefers a prophylactic small dose of NPH insulin, supplemented if necessary by regular insulin.
942
JURGEN STEINKE
The diabetic patient on an oral hypoglycemic agent may be handled in one of two ways. If the surgery is minor, the tablets are omitted preoperatively and are given before supper if of the short acting type (tolbutamide), or withheld until the next day if of the long-acting type (chlorpropamide).4 For example, a 62 year old diabetic man with a gangrenous toe could be managed in this way: (1) fasting blood glucose, (2) a slow infusion of 1000 ml. of 5 per cent dextrose in water preoperatively, during surgery, and in the immediate postoperative period, (3) spinal anesthesia for the toe amputation, followed in the later afternoon by 2 tablets of tolbutamide and a light supper. The alternative way of handling the patient who is taking an oral agent is to switch him temporarily to insulin. This is almost always indicated if the procedure is a major one, if general anesthesia is indicated, if the nature of surgery requires intravenous feeding for several days, or if the diabetes is poorly controlled. Insulin can be administered by the sliding scale technique (see above) or in the form of small amounts of intermediate insulin such as 10 to 20 units of NPH or lente insulin. This regimen can be continued on a once-a-day basis until oral intake can be resumed. Such small amounts of insulin are usually well tolerated and will prevent any excessive hyperglycemia. Although an article has recently appeared in the German literature proposing the intravenous administration of tolbutamide for these patients in the postoperative period,s insulin is preferred in this country. For the diabetic patient on insulin, one's plan will depend to a large extent on the type of surgical procedure and the hour of surgery. Such operations should be scheduled early in the morning so that the period of fasting is not prolonged. If the procedure is minor and is scheduled early, and if oral intake can be resumed that evening, insulin can be withheld until the patient is in the recovery room, at which time two thirds of his total dose is given. If a major surgical procedure is planned, it is best to reduce the total insulin dose by one third and to give one third before and one third after operation, to be supplemented in the postoperative period with regular insulin on a sliding scale if necessary. In this way, both hypo glycemia and severe hyperglycemia can be avoided. As an example, a 48 year old patient takes 15 U of regular insulin and 35 U of NPH insulin every morning. On the day of surgery the fasting bl00d glucose is determined; instead of breakfast a slow intravenous infusion with 5 per cent dextrose in saline or water is started, and 5 U of regular and 12 U of NPH insulin are given. In the recovery room in the afternoon, a second blood sugar is obtained, and he receives an additional 5 U of regular and 12 U of NPH insulin. If the blood sugar level is reported as above 200 mg. per 100 ml., or if a urine specimen shows a 4+ test for sugar, additional regular insulin will be given. In practice, however, this will rarely be necessary. If on the next day intravenous fluids are continued on a 24 hour basis, insulin can again be administered, one third in the morning and one third in the afternoon, adjustments being made on the basis of fasting and 3 P.M. blood sugars. Once the infusions are reduced or the patient is returned to oral feedings, insulin can be resumed in a single injection.
DIABETES IN THE SURGICAL PATIENT
943
There are physicians who fear the occurrence of hypo glycemia on the day of surgery because little or no food is taken on that day, and who therefore prefer to withhold all insulin until the postoperative period, when it is administered only by the sliding-scale technique. However, experience has shown that the combination of glucose given slowly intravenously and the metabolic effects of anxiety, surgery, and anesthesia will counterbalance the effect of preoperatively given insulin to a surprising degree. In actual practice hypo glycemia is uncommon. If hypoglycemia does occur, one of three conditions is usually responsible: (1) The patient has been on an unrestricted diet at home and therefore has been taking a large amount of insulin. Under controlled hospital conditions his caloric intake will be restricted, and if insulin is not markedly reduced, hypoglycemia will ensue during or after surgery. (2) In a known diabetic, hypophysectomy or removal of the adrenal glands will suddenly induce a state of marked insulin sensitivity and, if not anticipated, insulin will produce severe hypoglycemia. For these conditions, insulin should not be routinely prescribed in the postoperative period. If needed, it must be administered very cautiously in small doses. Ten units of regular insulin in these circumstances may cause severe hypo glycemia, resulting in convulsions. (3) The delivery of a pregnant diabetic patient. Almost all pregnant diabetic patients will require insulin, usually in rather large amounts, owing to insulin resistance caused mainly by hormonal placental factors such as corticosteroids and placental lactogen. Once the baby is delivered, either vaginally or by cesarean section, these factors disappear, and the patient will return suddenly to her prepregnancy state of insulin sensitivity. Therefore, hypo glycemia on the day of delivery is extremely common. It is best prevented by omitting all insulin on the scheduled day of delivery.
THE UNDIAGNOSED DIABETIC PATIENT It has been estimated by carefully carried out population surveys that there are as many undiagnosed as known diabetic subjects. For the United States that means the presence of some two million undiagnosed cases, most of them representing individuals above the age of 40. This has been borne out by the author's experience, in which approximately one third of diabetic patients scheduled to undergo surgery are newly diagnosed diabetic patients. It is surprising how well most of these people adjust to chronic hyperglycemia. Patients with blood glucose levels in the range of 200 to 300 mg. per 100 ml. may continue their daily chores, attributing nocturia to old age, weight loss to self-imposed diets for obesity, and fatigue to lack of a vacation. These patients may appear well compensated; however, under the stress of surgery, ketoacidosis may develop swiftly, with resultant dehydration. and electrolyte loss. Fortunately, this almost never happens, since it'is now a universal routine to test for diabetes on admission to any hospital. If glucosuria or hyperglycemia is detected, surgery should be postponed until the diabetic state can be evaluated
944
JURGEN STEINKE
by further urine tests, by blood tests taken 1 or 2 hours after meals, or by an oral glucose tolerance test. Only when the severity or mildness of the diabetes has been established and proper treatment has been initiated should one proceed with surgery. On the other hand, the presence of sugar in the urine does not always indicate diabetes mellitus; it may mean renal glucosuria which of course does not require any medical treatment. These patients, who under normal conditions lose variable amounts of sugar and therefore calories in the urine, easily develop starvation ketosis if they are fasted. It is not uncommon therefore that they will exhibit glycosuria and acetonuria, and thus become undistinguishable from true diabetics if only their urinary findings are taken into account.
UNCONTROLLED DIABETES AND EMERGENCY SURGERY Most diabetic patients are in a reasonable state of metabolic control, and emergency surgery can be performed immediately or within a few hours. A brief diabetic history including duration of the disease and previous treatment, a urine test for sugar, acetone and protein, a blood sugar determination sent to the laboratory and simultaneously tested with Dextrostix, a plasma acetone test done at the bedside, and a blood sample sent to the laboratory for bicarbonate, electrolyte, and urea nitrogen de terminations suffice for a rapid diabetic evaluation. If the diabetes is decompensated because it was not known or the underlying disease such as a severe infection intensified it, treatment is initiated immediately with intravenous fluids and insulin.'" The choice of fluid will vary from patient to patient. If he is severely dehydrated and has good cardiac and renal function, normal saline can be administered; 4 to 6 liters are usually required. If the cardiac reserve is borderline or poor, half normal saline is indicated. If the patient has nonketotic hyperosmolar coma with grossly elevated serum sodium, despite hyperglycemia, 5 per cent dextrose in water is probably better than saline. If there is any indication that lactic acidosis may be present in combination with ketoacidosis, as indicated by only moderately elevated blood sugar and serum ketones, but grossly depressed serum bicarbonate level, then liberal use of bicarbonate is justified. The amount of insulin will vary with the blood sugar, the timing of the last insulin dose, if any, and the duration and magnitude of the surgical procedure. None may be required until the postoperative period, or if the blood sugar is elevated, the usual daily insulin dose may be repeated preoperatively. If ketoacidosis is present, 50 units may have to be given by intravenous push and 50 subcutaneously, to be repeated every 2 hours if needed, as indicated by laboratory tests. It is important to realize that diabetic ketoacidosis per se may mimic an abdominal emergency such as an acute appendicitis ("pseudoappendicitis" of early diabetic ketoacidosis). Failure to recognize this possibility may be fatal. For example, a 16 year old previously healthy high school student is seen at the emergency ward with acute abdominal pain and vomiting. His white-cell count is 18,000
DIABETES IN THE SURGICAL PATIENT
945
per CU. mm; his urine gives a 4+ test for sugar, with a large amount of acetone. An immediate blood glucose is reported as 450 mg. per 100 ml., bicarbonate is 11 mEq. per liter. He is seen by both an internist and a surgeon. He is treated medically with a total of 75 units of insulin and 4 liters of normal saline intravenously and responds well. However, an identical clinical picture in another patient could have been due to acute appendicitis which led to the decompensation of diabetes. It is often impossible to make the correct differential diagnosis at the beginning; thus it is of utmost importance that such difficult situations be approached by a combined medical-surgical team.
REFERENCES 1. Allison, S. P., Tomlin, P. J., and Chamberlain, M. J.: Some effects of anesthesia and surgery on carbohydrate and fat metabolism. Brit. J. Anaesth., 41 :588-93, 1969. 2. Bunker, J. P., and Vandam, L. D.: Effects of anesthesia on metabolism and cellular function. Pharmacol. Rev., 17:183-263,1965. 3. Clark, R. S.: The hyperglycaemic response to different types of surgery and anaesthesia. Brit. J. Anaesth., 42:45-53, 1970. 4. Galloway, J. A., and Shuman, C. R.: Profile, specific methods of management and response of diabetic patients to anesthesia and surgery. Int. Anesth. Clin., 5:437-466, 1967. 5. Greene, N. M.: Carbohydrate metabolism and anesthesia. Int. Anesth. Clin., 5:411-426, 1967. 6. Marble, A., and Steinke, J.: Physiology and pharmacology in diabetes mellitus: Guiding the diabetic patient through the surgical period. Anesthesiol., 24:442, 1963. 7. Schweizer, D., and Howland, W. S.: Some metabolic changes associated with anesthesia and operation. Surg. Clin. N. Amer., 49:223-31,1969. 8. Schmitt, H., Liebermeister, H., LoSardo, G., and Daweke, H.: Treatment of maturity-onset diabetics with intravenous tolbutamide during surgery. Diabetologia, 4:307-308, 1968. 9. Shipp, J. C.: Diabetes mellitus, anesthesia, and surgery. Int. Anesth. Clin., 6:189-209, 1968. 10. Stanley, V. F., Giesecke, A. H., Jr., and Seltzer, H. S.: Anesthesia for the diabetic patient. Clin. Anesth.,3:264-74, 1968. 11. Steinke, J.: Management of diabetes mellitus and surgery. New Eng. J. Med., 282:14721474,1970. 12. Steinke, J., and Thorn, G. W.: Diabetes mellitus. In Harrison, T. R., ed.: Principles of Internal Medicine. New York, McGraw Hill Book Co., New York, 6th ed., 1970. 170 Pilgrim Road Boston, Massachusetts 02215