- Email: [email protected]
An Anesthetic Perspective on Vascular Surgery of the Abdomen
An Anesthetic Perspective on Vascular Surgery of the Abdomen ALAN D. SESSLER, M.D. EDWARD P. DIDIER, M.D.
This discussion concerns the anesthetic management for operations involving aneurysms, occlusive disease, embolism, and thrombosis of the major vessels of the abdomen. Most of the patients with these disorders are men in the sixth and seventh decades of life who have generalized arteriosclerosis that is more severe than that normally attributed to this degree of aging. A great number have advanced vascular disease in other organs, as evidenced by hypertension, previous myocardial infarctions, cerebral vascular insufficiency, or diminution in renal performance. Many of the younger men and some women have concomitant metabolic disease (most commonly diabetes mellitus or hypercholesterolemia) that has hastened the deterioration of the vascular system. Hence, as anesthetic and surgical candidates they must be categorized as higher than average risks. At the outset it must be realized that many of the surgical procedures for these conditions are palliative rather than curative, because of the nature of the patient or the nature of the disease, or both. An exception is renal artery surgery, wherein the patient, often a woman, is usually younger and, though hypertensive, is otherwise healthy. In such a case a good result offers many years of useful activity. The majority of patients, however, although given additional years of life, often fail to return to full, active employment. Among the surgical procedures performed are those for leaking or ruptured aneurysm, or for repair after trauma to a major vessel. In addition, acute thrombosis or embolism may present as an emergency;6 these occur in patients with atrial fibrillation and thrombus formation in the left atrium or as a consequence of myocardial infarction with thrombosis in the left ventricle. The nonsurgical lesions are usually those in which the distal vascular tree is extensively occluded, thereby making it impossible to improve the blood flow to the limb. Here the question of surgical sympathectomy is 881
882
ALAN D. SESSLER, EDWARD
P.
DIDIER
raised; although popular in the past, this technique has given disappointing results. The anesthetic problems in these cases differ little from those encountered in other abdominal operations. Adequate control of ventilation via an endotracheal tube is important. Relaxation enabling access to structures deep within the abdomen and facilitating closure of the large incision is a basic requirement. Support of the cardiovascular system in the presence of visceral manipulation and blood loss demand close attention and necessitate light planes of anesthesia. While these operations are possible under conduction anesthesia, the advantage gained from the sympathetic block seems to be outweighed by the restlessness that occurs with procedures of this duration in an awake patient. If the patients are heavily sedated, the airway is less than perfect and there are potential problems with conduction anesthesia in the presence of hemorrhage. Beyond these general considerations, specific problems in patients of this age group and in patients with associated diseases merit attention.
ANALYSIS OF 100 CONSECUTIVE CASES
The histories of 100 consecutive vascular cases were reviewed (Table 1). Seven anesthetists and five surgeons conducted the management of these cases. Rather than any routine of anesthesia, great variation was found in the selection of anesthetic agents, muscle relaxants, and use of vasopressors, intravenous fluids, atropine, and prostigmine, as well as in the use of venous pressure as an aid in blood replacement. In the selection of anesthetic agents, all patients received thiopental Table 1.
Data in 100 Operations jar Abdominal Vascular Disease ABDOMINAL AORTIC ANEURYSM
N umber of cases
72 Elective Ruptured
Sex
Male Female
RENAL ARTERY STENOSIS
19
9
66
56
46
64
15
5
8
4
4
3.6
1.1
68 Age (yr., av.)
AORTO-ILIAC OCCLUSIVE DISEASE
4
Elective Ruptured Blood transfusions (units, av.) Aortic clamping (min., av.)
3.3
11
55
58
ANESTHETIC PERSPECTIVE ON VASCULAR SURGERY OF THE ABDOMEN
883
for induction, and nearly all, some combination of nitrous oxide and oxygen during maintenance. Some patients received a thiopental-narc oticnitrous oxide-relaxant anesthesia; others, nitrous oxide-oxygen-halothane; and when electrocautery did not preclude its use, nitrous oxide-oxygenether was sometimes used. No agent or combination of agents was found to be superior. The one criterion was whether an agent would produce a light anesthesia whose depressant effects could be rapidly removed if massive blood loss were encountered. Succinylcholine was the muscle relaxant used in 41 cases; the mean dose was 527 mg. and the range 110 to 1260 mg. Curare was used in 43 patients, the mean dose being 38 mg. and the range 15 to 60 mg. Dimethyl curare was used in 10 patients, at a mean dose of 11 mg. and a range of 6 to 20 mg. The average duration of anesthesia in all cases was 266 minutes. One half of the patients who received curare were given prostigmine preceded by atropine for reversal of the effects of the curare. Vasopressors were used during anesthesia in 40 patients. Mephentermine was used in 19 patients, ephedrine in 13, phenylephrine in 8, and methoxamine and metaraminol each in 2 instances. The preference was for shorter-acting va so pressors with both a central and a peripheral action, and there was a tendency to resort to a continuous vasopressor drip only in the face of hypotension refractory to the former method. Circumstances requiring va so pressors were most frequently encountered during exploration of the abdomen and packing away of the small bowel, as well as with the release of aortic clamping. The use of atropine averted the necessity of using vasopressors in some of the abdominal problems, and the use of blood in some instances of aortic unclamping. A fall in arterial pressure of 40 mm. Hg or greater was seen in 60 of the cases, most frequently with removal of aortic clamps. Rapid changes in hemodynamics accompanied clamping and unclamping of the aorta. Hypertension following clamping was never severe enough to require the use of hypotensive agents. A moderate hypotension with the release of aortic clamps facilitated clot formation in the interstices of the graft and stitch holes of the anastomoses. Unclamping poses a problem. 3 , 7, 9 On the one hand a moderately deep anesthetic, particularly with halothane, results in too severe a hypotension, and the need for excessive transfusion of blood if one shuns vasopressors and maintains the arterial pressure by whole blood. On the other hand, although removal of the halothane conserves blood, it often results in hiccoughing or other diaphragmatic motion which may be accentuated by the lower pH and higher pC0 2 that occur following restoration of flow to areas that were underperfused during the period of clamping. A middle course of light halothane anesthesia, moderate hypotension, transfusion of blood, and, when necessary, a small amount of short-acting vasopressor becomes the most frequent solution. Blood loss and its replacement are major considerations. Venous pres-
884
ALAN D. SESSLER,
EDWARD
P. DIDIER
sure measurement was used as an aid in guiding replacement in 48 of the cases reviewed. Blood transfusions average 3.3 units in the elective aneurysm resections, 3.6 units in cases of bypass grafts and endarterectomies, and 1.1 units in operations on the renal arteries. Calcium gluconate was given to 10 patients along with the transfusion of blood. Postoperative renal performance was related to the duration of aortic clamping, but data were insufficient to permit determining correlation coefficients. Average clamping time was 55 minutes for the aneurysm resections, many patients having received bifurcation grafts. Mannitol was used in 43 patients, and many of the others received a liter of 5 per cent glucose and water or Ringer's lactate solution. The rationale for this procedure is that the body seems to adjust its homeostatic mechanisms better with water than with whole blood, if renal function is good and enough hemoglobin is present to assure adequate transport of oxygen. 2 , 8 There were no operative deaths and six hospital deaths, two of these occurring among the four patients with ruptured aneurysms. Renal shutdown, the most frequent major complication, occurred in six patients. Four of these died and two were successfully treated by dialysis. The aortic clamp was placed above the renal arteries for 14 minutes in two of these cases and for 30 minutes in one. Wound dehiscence occurred in three patients, ileus in three, pulmonary embolism in two, and cardiac arrhythmias requiring therapy in four. These results serve to accentuate the risks and problems associated with major surgical procedures in patients in this age group. The patients who died and those who experienced difficulty are discussed briefly below.
MORTALITY CASE 1. A 58-year-old man was admitted for emergency operation because of a leaking abdominal aortic aneurysm. At operation, multiple aneurysms were found in the aorta and the iliac and external iliac arteries. He had a smooth postoperative course and was dismissed from the hospital on the tenth day postoperatively. On the eleventh day, on arising from bed, he had a massive pulmonary embolism. CASE 2. A 61-year-old man was operated on for abdominal aortic aneurysm. Because of the extent of the aneurysm, it was necessary to apply the clamp above the renal arteries. Postoperatively, there was anuria, and despite dialysis (three periods), ion-exchange enema, and a meticulous fluid and electrolyte program, his course was progressively downhill. Death occurred on the eighteenth day after operation. CASE 3. A 66-year-old man was operated on for abdominal aortic aneurysm. Considerable leakage from the aneurysm had produced dense fibrosis in the area, and it was necessary to clamp above the renal arteries for about 30 minutes. Because of uncontrollable oozing, the patient received 28 units of blood. His postoperative course was characterized by anuria and bloody stools. He died on the third day after operation.
ANESTHETIC PERSPECTIVE ON VASCULAR SURGERY OF THE ABDOMEN
885
CASE 4. A 43-year-old woman had relentless hypercholesteremia. Aorto-iliac endarterectomy was performed in 1961 with fair results, but the symptoms recurred and another endarterectomy was performed in 1963. Because of postoperative bleeding, reoperation was performed for control of bleeding and clot removal. After the emergency procedure, acute renal failure and massive gastrointestinal infarction developed, and the patient died. CASE 5. A 56-year-old man had a history of old myocardial infarction and abdominal aortic aneurysm with extension to the iliac vessels. At operation endarterectomy was performed on the proximal portion of the aorta, and a bifurcation graft was placed. Because of oliguria another operation was performed on the following day, and a bypass graft was placed for an occluded right renal artery. The next day the patient continued to have anuria, and he died suddenly from what appeared to be an acute myocardial infarction. CASE 6. A 52-year-old woman with angina pectoris, basilar artery insufficiency, and hypercholesteremia had received an aortic homograft in 1954 and a Dacron aorto-iliac bypass graft in 1963. She had received anticoagulants and bled from the proximal anastomosis of her bypass graft. The graft was removed, but she bled postoperatively and succumbed the day following surgery.
MORBIDITY CASE 1. A 63-year-old man had an abdominal aortic aneurysm, right inguinal hernia, and carcinoma of the prostate. At operation, an aorto-iliac bifurcation graft was placed and an inguinal herniorrhaphy was performed. On the seventh day postoperatively, separation of the wound necessitated secondary closure under anesthesia. His further course was satisfactory. CASE 2. A 46-year-old man had aorto-iliac occlusive disease and underwent a surgical procedure involving endarterectomy and aorto-right iliac-left femoral bypass graft. After six days of moderate wound infection postoperatively the wound separated, and secondary closure was performed under anesthesia. Since that time his course has been good. CASE 3. A 64-year-old man had abdominal aortic aneurysm, liver insufficiency, and cirrhosis. After operation for the aneurysm, his course was complicated by renal shutdown requiring three periods of dialysis, multiple transfusions for anemia caused by bacterial infection of the wound, and an organic confusional state. He was finally dismissed from the hospital after five months, in good condition. CASE 4. A 68-year-old man underwent resection of an abdominal aortic aneurysm and replacement with a straight Dacron graft. His course postoperatively was complicated by chronic bronchitis and emphysema, chronic duodenal ulcer, and benign prostatic hypertrophy. Fifteen days after operation partial separation of the wound occurred, which was repaired under general anesthesia without difficulty CASE 5. A 64-year-old man underwent emergency surgery for a ruptured abdominal aortic aneurysm with proximal extension to the renal arteries and involvement of both iliac arteries. A Dacron prosthesis was substituted for the aneurysmal vessels, but the patient was anuric postoperatively. After one dialysis, renal function gradually returned, and the patient was dismissed much improved.
886
ALAN D. SESSLER, EDWARD P. DIDIER
SPECIFIC ANESTHETIC PROBLEMS
The reduction in vascular elasticity together with the systemic arterial hypertension which is often seen as part of the basic vascular disease results in greater fluctuations in blood pressure and flow when homeostasis is disrupted by anesthesia, surgery, and blood loss. Controversy still exists over the wisdom of anesthetizing a patient who is receiving antihypertensive drugs. Current thinking favors the thesis that these agents are not a contraindication to anesthesia but that patients with hypertension present a greater risk; thus, the hypertension rather than the presence of drugs is the factor that makes one proceed with more than average caution. (The drugs themselves have been shown not to increase the frequency, depth, or responsiveness of hypotension during anesthesia and surgery.)l. 4 Cardiac disease in the forms of myocardial infarction and congestive heart failure were frequently recorded in the 100 consecutive histories of the patients reviewed. Although many received digitalis, few, if any, were digitalized in preparation for the stress of operation. In view of the frequency of cardiac disease, one might fear a high incidence of pulmonary edema from overloading of the vascular compartment by blood and fluid replacement. However, evidence of this was rare; in fact, the additional transfusions frequently given postoperatively suggest that replacement was inadequate. Many of the patients with cardiac disease receive digitalis and diuretics. If in these patients there are massive changes in the volume and composition of intravascular fluid during surgery, the potassium level may drop so low that there is evidence of digitalis toxicity. A closely related consideration is the common practice of administering calcium along with large volumes of whole blood. This calcium is not necessary to ensure coagulation. With very rare exceptions, calcium probably plays little part in preventing citrate intoxication. However, like digitalis, calcium increases the contractility of the myocardium and when given for this purpose is highly beneficial. It would seem axiomatic to counsel giving calcium with caution to patients who are receiving digitalis, since the contractility of the myocardium may be increased to the point of irritability. 6 Several decades of medical practice notwithstanding, it seems basic that it is more physiologic to transfuse normothermic man with warm blood unless one desires and is prepared for hypothermia. Anticoagulants also merit attention. Patients requiring embolectomy as an emergency procedure often have been receiving anticoagulants as part of therapy for myocardial infarction, in the hope of forestalling further embolization after valve replacement, or because of mitral stenosis with atrial fibrillation and a history of previous embolization. When a true emergency exists, reversal of the anticoagulant effect by means of vitamin K to obtain a nearly normal clotting mechanism for operation is carried out; but in performing any elective procedure the reduction of the anti-
ANESTHETIC PERSPECTIVE ON VASCULAR SURGERY OF THE ABDOMEN
887
coagulant effect and the avoidance of a rebound hypercoagulability is a difficult, time-consuming, and occasionally hazardous maneuver. One should also consider the hazards before performing a lumbar sympathetic block on a patient with an ischemic leg who is receiving anticoagulants. The amount of heparin injected distal to vascular clamps during these procedures is merely a fraction of a true heparinizing dose, but it may be a factor of concern in a patient who shows signs of hypocoagulability in the immediate postoperative period. Cerebral vascular insufficiency, chronic bronchitis and emphysema, and diabetes are problems that are frequently met. Anesthetic implications of cerebral vascular insufficiency are that the patient might be receiving anticoagulants, could possibly suffer from hypotension, and might run less risk of cerebral complication if ventilated so that a normal arterial pC0 2 and cerebral blood flow are maintained. The pulmonary problems are of greatest significance in the postoperative period, when there is a transfer from controlled ventilation to spontaneous ventilation. The large abdominal incision limits depth of respiration, and paroxysms of coughing may hinder wound-healing. Diabetic patients, when well prepared, rarely present an anesthetic problem. Intravenous administration of fluid containing glucose raises their blood sugar, but this is the safer path to tread. Shock of hypoglycemic origin should be kept in mind, together with the fact that the orally administered agents are capable of producing hypoglycemia several days after use of the drug has been stopped.
POSTOPERATIVE PROBLEMS AND MANAGEMENT
The immediate concern of the anesthetist is to return to the care of the surgeon a patient who has been brought to a state of equilibrium after the operative procedure. It is unrealistic to believe that the anesthetist can accomplish this in the minutes before the patient leaves the operating room, hence the responsibility for care should be divided between anesthetist and surgeon in the first few hours of the postoperative period. The anesthetist's responsibility for a patient continues until such time as the physiologic effects of drugs which he has administered have ended. Realistically this turns out to be one to three hours after the end of the operation, except when ventilation continues marginally and then his concern in the patient's care properly continues until the endotracheal tube is removed and the patient is no longer receiving assisted ventilation. We feel that providing ventilatory assistance reaps benefits in terms of decreased morbidity and mortality in those patients for whom the risk of operation and anesthesia is greater than average.
888
ALAN D. SESSLER, EDWARD
P.
DIDIER
SUMMARY The histories of 100 consecutive patients who underwent abdominal vascular surgery were reviewed from the standpoint of diagnosis, anesthetic management, and outcome. It was apparent that this group represented a greater risk during anesthesia because of advanced age and generalized cardiovascular and renal disease in addition to the surgical condition. The more frequent and significant problems were discussed on the basis of our experience, and the following conclusions were reached: 1. This type of surgery is generally palliative, and serves to prolong comfortable life rather than normalcy. 2. Anesthetic problems are the same as those seen in patients of similar age groups but are complicated by the possibility of sudden major blood loss and rapid blood pressure changes. 3. The most frequent postoperative complication is renal hypofunction.
REFERENCES 1. Alper, M. H., Flacke, Werner, and Krayer, Otto: Pharmacology of reserpine and its implications for anesthesia. Anesthesiology 24:524-542 (July-Aug.) 1963. 2. Barry, K. G., Cohen, Arthur, Knochel, J. P., Whelan, T. J., Jr., and Beisel, W. R.: Mannitol infusion. II. The prevention of acute functional renal failure during resection of an aneurysm of the abdominal aorta. New England J. Med. 264: 967-971 (May 11) 1961. 3. Fry, W. J., Keitzer, W. F., Kraft, R. 0., and De Weese, M. S.: Prevention of hypotension due to aortic release. Surg., Gynec. & Obst. 116:301-306 (March) 1963. 4. Katz, R. L., Weintraub, H. D., and Papper, E. M.: Anesthesia, surgery and rauwolfia. Anesthesiology 25:142-147 (March-April) 1964. 5. Keats, A. S., and Jackson, L.: Anesthesia for emergency cardiovascular surgery. Clin. Anesth. 2: 47-70, 1963. 6. Lown, Bernard, Black, Harrison, and Moore, F. D.: Digitalis, electrolytes and the surgical patient. Am. J. Cardiol. 6:309-337 (Aug.) 1960. 7. Malette, W. G., Armstrong, R. G., and Criscuolo, Dominic: A second mechanism in hypotension following release of abdominal aortic clamps. S. Forum 14:292, 1963. 8. Moore, F. D.: Tris buffer, mannitol and low viscous dextran: Three new solutions for old problems. S. CLIN. NORTH AMERICA 43:577-596 (June) 1963. 9. Rader, L. E., Jr., Keith, H. B., and Campbell, G. S.: Mechanism of hypotension following release of abdominal aortic clamps. S. Forum 12:265-267, 1961.
This discussion concerns the anesthetic management for operations involving aneurysms, occlusive disease, embolism, and thrombosis of the major vessels of the abdomen. Most of the patients with these disorders are men in the sixth and seventh decades of life who have generalized arteriosclerosis that is more severe than that normally attributed to this degree of aging. A great number have advanced vascular disease in other organs, as evidenced by hypertension, previous myocardial infarctions, cerebral vascular insufficiency, or diminution in renal performance. Many of the younger men and some women have concomitant metabolic disease (most commonly diabetes mellitus or hypercholesterolemia) that has hastened the deterioration of the vascular system. Hence, as anesthetic and surgical candidates they must be categorized as higher than average risks. At the outset it must be realized that many of the surgical procedures for these conditions are palliative rather than curative, because of the nature of the patient or the nature of the disease, or both. An exception is renal artery surgery, wherein the patient, often a woman, is usually younger and, though hypertensive, is otherwise healthy. In such a case a good result offers many years of useful activity. The majority of patients, however, although given additional years of life, often fail to return to full, active employment. Among the surgical procedures performed are those for leaking or ruptured aneurysm, or for repair after trauma to a major vessel. In addition, acute thrombosis or embolism may present as an emergency;6 these occur in patients with atrial fibrillation and thrombus formation in the left atrium or as a consequence of myocardial infarction with thrombosis in the left ventricle. The nonsurgical lesions are usually those in which the distal vascular tree is extensively occluded, thereby making it impossible to improve the blood flow to the limb. Here the question of surgical sympathectomy is 881
882
ALAN D. SESSLER, EDWARD
P.
DIDIER
raised; although popular in the past, this technique has given disappointing results. The anesthetic problems in these cases differ little from those encountered in other abdominal operations. Adequate control of ventilation via an endotracheal tube is important. Relaxation enabling access to structures deep within the abdomen and facilitating closure of the large incision is a basic requirement. Support of the cardiovascular system in the presence of visceral manipulation and blood loss demand close attention and necessitate light planes of anesthesia. While these operations are possible under conduction anesthesia, the advantage gained from the sympathetic block seems to be outweighed by the restlessness that occurs with procedures of this duration in an awake patient. If the patients are heavily sedated, the airway is less than perfect and there are potential problems with conduction anesthesia in the presence of hemorrhage. Beyond these general considerations, specific problems in patients of this age group and in patients with associated diseases merit attention.
ANALYSIS OF 100 CONSECUTIVE CASES
The histories of 100 consecutive vascular cases were reviewed (Table 1). Seven anesthetists and five surgeons conducted the management of these cases. Rather than any routine of anesthesia, great variation was found in the selection of anesthetic agents, muscle relaxants, and use of vasopressors, intravenous fluids, atropine, and prostigmine, as well as in the use of venous pressure as an aid in blood replacement. In the selection of anesthetic agents, all patients received thiopental Table 1.
Data in 100 Operations jar Abdominal Vascular Disease ABDOMINAL AORTIC ANEURYSM
N umber of cases
72 Elective Ruptured
Sex
Male Female
RENAL ARTERY STENOSIS
19
9
66
56
46
64
15
5
8
4
4
3.6
1.1
68 Age (yr., av.)
AORTO-ILIAC OCCLUSIVE DISEASE
4
Elective Ruptured Blood transfusions (units, av.) Aortic clamping (min., av.)
3.3
11
55
58
ANESTHETIC PERSPECTIVE ON VASCULAR SURGERY OF THE ABDOMEN
883
for induction, and nearly all, some combination of nitrous oxide and oxygen during maintenance. Some patients received a thiopental-narc oticnitrous oxide-relaxant anesthesia; others, nitrous oxide-oxygen-halothane; and when electrocautery did not preclude its use, nitrous oxide-oxygenether was sometimes used. No agent or combination of agents was found to be superior. The one criterion was whether an agent would produce a light anesthesia whose depressant effects could be rapidly removed if massive blood loss were encountered. Succinylcholine was the muscle relaxant used in 41 cases; the mean dose was 527 mg. and the range 110 to 1260 mg. Curare was used in 43 patients, the mean dose being 38 mg. and the range 15 to 60 mg. Dimethyl curare was used in 10 patients, at a mean dose of 11 mg. and a range of 6 to 20 mg. The average duration of anesthesia in all cases was 266 minutes. One half of the patients who received curare were given prostigmine preceded by atropine for reversal of the effects of the curare. Vasopressors were used during anesthesia in 40 patients. Mephentermine was used in 19 patients, ephedrine in 13, phenylephrine in 8, and methoxamine and metaraminol each in 2 instances. The preference was for shorter-acting va so pressors with both a central and a peripheral action, and there was a tendency to resort to a continuous vasopressor drip only in the face of hypotension refractory to the former method. Circumstances requiring va so pressors were most frequently encountered during exploration of the abdomen and packing away of the small bowel, as well as with the release of aortic clamping. The use of atropine averted the necessity of using vasopressors in some of the abdominal problems, and the use of blood in some instances of aortic unclamping. A fall in arterial pressure of 40 mm. Hg or greater was seen in 60 of the cases, most frequently with removal of aortic clamps. Rapid changes in hemodynamics accompanied clamping and unclamping of the aorta. Hypertension following clamping was never severe enough to require the use of hypotensive agents. A moderate hypotension with the release of aortic clamps facilitated clot formation in the interstices of the graft and stitch holes of the anastomoses. Unclamping poses a problem. 3 , 7, 9 On the one hand a moderately deep anesthetic, particularly with halothane, results in too severe a hypotension, and the need for excessive transfusion of blood if one shuns vasopressors and maintains the arterial pressure by whole blood. On the other hand, although removal of the halothane conserves blood, it often results in hiccoughing or other diaphragmatic motion which may be accentuated by the lower pH and higher pC0 2 that occur following restoration of flow to areas that were underperfused during the period of clamping. A middle course of light halothane anesthesia, moderate hypotension, transfusion of blood, and, when necessary, a small amount of short-acting vasopressor becomes the most frequent solution. Blood loss and its replacement are major considerations. Venous pres-
884
ALAN D. SESSLER,
EDWARD
P. DIDIER
sure measurement was used as an aid in guiding replacement in 48 of the cases reviewed. Blood transfusions average 3.3 units in the elective aneurysm resections, 3.6 units in cases of bypass grafts and endarterectomies, and 1.1 units in operations on the renal arteries. Calcium gluconate was given to 10 patients along with the transfusion of blood. Postoperative renal performance was related to the duration of aortic clamping, but data were insufficient to permit determining correlation coefficients. Average clamping time was 55 minutes for the aneurysm resections, many patients having received bifurcation grafts. Mannitol was used in 43 patients, and many of the others received a liter of 5 per cent glucose and water or Ringer's lactate solution. The rationale for this procedure is that the body seems to adjust its homeostatic mechanisms better with water than with whole blood, if renal function is good and enough hemoglobin is present to assure adequate transport of oxygen. 2 , 8 There were no operative deaths and six hospital deaths, two of these occurring among the four patients with ruptured aneurysms. Renal shutdown, the most frequent major complication, occurred in six patients. Four of these died and two were successfully treated by dialysis. The aortic clamp was placed above the renal arteries for 14 minutes in two of these cases and for 30 minutes in one. Wound dehiscence occurred in three patients, ileus in three, pulmonary embolism in two, and cardiac arrhythmias requiring therapy in four. These results serve to accentuate the risks and problems associated with major surgical procedures in patients in this age group. The patients who died and those who experienced difficulty are discussed briefly below.
MORTALITY CASE 1. A 58-year-old man was admitted for emergency operation because of a leaking abdominal aortic aneurysm. At operation, multiple aneurysms were found in the aorta and the iliac and external iliac arteries. He had a smooth postoperative course and was dismissed from the hospital on the tenth day postoperatively. On the eleventh day, on arising from bed, he had a massive pulmonary embolism. CASE 2. A 61-year-old man was operated on for abdominal aortic aneurysm. Because of the extent of the aneurysm, it was necessary to apply the clamp above the renal arteries. Postoperatively, there was anuria, and despite dialysis (three periods), ion-exchange enema, and a meticulous fluid and electrolyte program, his course was progressively downhill. Death occurred on the eighteenth day after operation. CASE 3. A 66-year-old man was operated on for abdominal aortic aneurysm. Considerable leakage from the aneurysm had produced dense fibrosis in the area, and it was necessary to clamp above the renal arteries for about 30 minutes. Because of uncontrollable oozing, the patient received 28 units of blood. His postoperative course was characterized by anuria and bloody stools. He died on the third day after operation.
ANESTHETIC PERSPECTIVE ON VASCULAR SURGERY OF THE ABDOMEN
885
CASE 4. A 43-year-old woman had relentless hypercholesteremia. Aorto-iliac endarterectomy was performed in 1961 with fair results, but the symptoms recurred and another endarterectomy was performed in 1963. Because of postoperative bleeding, reoperation was performed for control of bleeding and clot removal. After the emergency procedure, acute renal failure and massive gastrointestinal infarction developed, and the patient died. CASE 5. A 56-year-old man had a history of old myocardial infarction and abdominal aortic aneurysm with extension to the iliac vessels. At operation endarterectomy was performed on the proximal portion of the aorta, and a bifurcation graft was placed. Because of oliguria another operation was performed on the following day, and a bypass graft was placed for an occluded right renal artery. The next day the patient continued to have anuria, and he died suddenly from what appeared to be an acute myocardial infarction. CASE 6. A 52-year-old woman with angina pectoris, basilar artery insufficiency, and hypercholesteremia had received an aortic homograft in 1954 and a Dacron aorto-iliac bypass graft in 1963. She had received anticoagulants and bled from the proximal anastomosis of her bypass graft. The graft was removed, but she bled postoperatively and succumbed the day following surgery.
MORBIDITY CASE 1. A 63-year-old man had an abdominal aortic aneurysm, right inguinal hernia, and carcinoma of the prostate. At operation, an aorto-iliac bifurcation graft was placed and an inguinal herniorrhaphy was performed. On the seventh day postoperatively, separation of the wound necessitated secondary closure under anesthesia. His further course was satisfactory. CASE 2. A 46-year-old man had aorto-iliac occlusive disease and underwent a surgical procedure involving endarterectomy and aorto-right iliac-left femoral bypass graft. After six days of moderate wound infection postoperatively the wound separated, and secondary closure was performed under anesthesia. Since that time his course has been good. CASE 3. A 64-year-old man had abdominal aortic aneurysm, liver insufficiency, and cirrhosis. After operation for the aneurysm, his course was complicated by renal shutdown requiring three periods of dialysis, multiple transfusions for anemia caused by bacterial infection of the wound, and an organic confusional state. He was finally dismissed from the hospital after five months, in good condition. CASE 4. A 68-year-old man underwent resection of an abdominal aortic aneurysm and replacement with a straight Dacron graft. His course postoperatively was complicated by chronic bronchitis and emphysema, chronic duodenal ulcer, and benign prostatic hypertrophy. Fifteen days after operation partial separation of the wound occurred, which was repaired under general anesthesia without difficulty CASE 5. A 64-year-old man underwent emergency surgery for a ruptured abdominal aortic aneurysm with proximal extension to the renal arteries and involvement of both iliac arteries. A Dacron prosthesis was substituted for the aneurysmal vessels, but the patient was anuric postoperatively. After one dialysis, renal function gradually returned, and the patient was dismissed much improved.
886
ALAN D. SESSLER, EDWARD P. DIDIER
SPECIFIC ANESTHETIC PROBLEMS
The reduction in vascular elasticity together with the systemic arterial hypertension which is often seen as part of the basic vascular disease results in greater fluctuations in blood pressure and flow when homeostasis is disrupted by anesthesia, surgery, and blood loss. Controversy still exists over the wisdom of anesthetizing a patient who is receiving antihypertensive drugs. Current thinking favors the thesis that these agents are not a contraindication to anesthesia but that patients with hypertension present a greater risk; thus, the hypertension rather than the presence of drugs is the factor that makes one proceed with more than average caution. (The drugs themselves have been shown not to increase the frequency, depth, or responsiveness of hypotension during anesthesia and surgery.)l. 4 Cardiac disease in the forms of myocardial infarction and congestive heart failure were frequently recorded in the 100 consecutive histories of the patients reviewed. Although many received digitalis, few, if any, were digitalized in preparation for the stress of operation. In view of the frequency of cardiac disease, one might fear a high incidence of pulmonary edema from overloading of the vascular compartment by blood and fluid replacement. However, evidence of this was rare; in fact, the additional transfusions frequently given postoperatively suggest that replacement was inadequate. Many of the patients with cardiac disease receive digitalis and diuretics. If in these patients there are massive changes in the volume and composition of intravascular fluid during surgery, the potassium level may drop so low that there is evidence of digitalis toxicity. A closely related consideration is the common practice of administering calcium along with large volumes of whole blood. This calcium is not necessary to ensure coagulation. With very rare exceptions, calcium probably plays little part in preventing citrate intoxication. However, like digitalis, calcium increases the contractility of the myocardium and when given for this purpose is highly beneficial. It would seem axiomatic to counsel giving calcium with caution to patients who are receiving digitalis, since the contractility of the myocardium may be increased to the point of irritability. 6 Several decades of medical practice notwithstanding, it seems basic that it is more physiologic to transfuse normothermic man with warm blood unless one desires and is prepared for hypothermia. Anticoagulants also merit attention. Patients requiring embolectomy as an emergency procedure often have been receiving anticoagulants as part of therapy for myocardial infarction, in the hope of forestalling further embolization after valve replacement, or because of mitral stenosis with atrial fibrillation and a history of previous embolization. When a true emergency exists, reversal of the anticoagulant effect by means of vitamin K to obtain a nearly normal clotting mechanism for operation is carried out; but in performing any elective procedure the reduction of the anti-
ANESTHETIC PERSPECTIVE ON VASCULAR SURGERY OF THE ABDOMEN
887
coagulant effect and the avoidance of a rebound hypercoagulability is a difficult, time-consuming, and occasionally hazardous maneuver. One should also consider the hazards before performing a lumbar sympathetic block on a patient with an ischemic leg who is receiving anticoagulants. The amount of heparin injected distal to vascular clamps during these procedures is merely a fraction of a true heparinizing dose, but it may be a factor of concern in a patient who shows signs of hypocoagulability in the immediate postoperative period. Cerebral vascular insufficiency, chronic bronchitis and emphysema, and diabetes are problems that are frequently met. Anesthetic implications of cerebral vascular insufficiency are that the patient might be receiving anticoagulants, could possibly suffer from hypotension, and might run less risk of cerebral complication if ventilated so that a normal arterial pC0 2 and cerebral blood flow are maintained. The pulmonary problems are of greatest significance in the postoperative period, when there is a transfer from controlled ventilation to spontaneous ventilation. The large abdominal incision limits depth of respiration, and paroxysms of coughing may hinder wound-healing. Diabetic patients, when well prepared, rarely present an anesthetic problem. Intravenous administration of fluid containing glucose raises their blood sugar, but this is the safer path to tread. Shock of hypoglycemic origin should be kept in mind, together with the fact that the orally administered agents are capable of producing hypoglycemia several days after use of the drug has been stopped.
POSTOPERATIVE PROBLEMS AND MANAGEMENT
The immediate concern of the anesthetist is to return to the care of the surgeon a patient who has been brought to a state of equilibrium after the operative procedure. It is unrealistic to believe that the anesthetist can accomplish this in the minutes before the patient leaves the operating room, hence the responsibility for care should be divided between anesthetist and surgeon in the first few hours of the postoperative period. The anesthetist's responsibility for a patient continues until such time as the physiologic effects of drugs which he has administered have ended. Realistically this turns out to be one to three hours after the end of the operation, except when ventilation continues marginally and then his concern in the patient's care properly continues until the endotracheal tube is removed and the patient is no longer receiving assisted ventilation. We feel that providing ventilatory assistance reaps benefits in terms of decreased morbidity and mortality in those patients for whom the risk of operation and anesthesia is greater than average.
888
ALAN D. SESSLER, EDWARD
P.
DIDIER
SUMMARY The histories of 100 consecutive patients who underwent abdominal vascular surgery were reviewed from the standpoint of diagnosis, anesthetic management, and outcome. It was apparent that this group represented a greater risk during anesthesia because of advanced age and generalized cardiovascular and renal disease in addition to the surgical condition. The more frequent and significant problems were discussed on the basis of our experience, and the following conclusions were reached: 1. This type of surgery is generally palliative, and serves to prolong comfortable life rather than normalcy. 2. Anesthetic problems are the same as those seen in patients of similar age groups but are complicated by the possibility of sudden major blood loss and rapid blood pressure changes. 3. The most frequent postoperative complication is renal hypofunction.
REFERENCES 1. Alper, M. H., Flacke, Werner, and Krayer, Otto: Pharmacology of reserpine and its implications for anesthesia. Anesthesiology 24:524-542 (July-Aug.) 1963. 2. Barry, K. G., Cohen, Arthur, Knochel, J. P., Whelan, T. J., Jr., and Beisel, W. R.: Mannitol infusion. II. The prevention of acute functional renal failure during resection of an aneurysm of the abdominal aorta. New England J. Med. 264: 967-971 (May 11) 1961. 3. Fry, W. J., Keitzer, W. F., Kraft, R. 0., and De Weese, M. S.: Prevention of hypotension due to aortic release. Surg., Gynec. & Obst. 116:301-306 (March) 1963. 4. Katz, R. L., Weintraub, H. D., and Papper, E. M.: Anesthesia, surgery and rauwolfia. Anesthesiology 25:142-147 (March-April) 1964. 5. Keats, A. S., and Jackson, L.: Anesthesia for emergency cardiovascular surgery. Clin. Anesth. 2: 47-70, 1963. 6. Lown, Bernard, Black, Harrison, and Moore, F. D.: Digitalis, electrolytes and the surgical patient. Am. J. Cardiol. 6:309-337 (Aug.) 1960. 7. Malette, W. G., Armstrong, R. G., and Criscuolo, Dominic: A second mechanism in hypotension following release of abdominal aortic clamps. S. Forum 14:292, 1963. 8. Moore, F. D.: Tris buffer, mannitol and low viscous dextran: Three new solutions for old problems. S. CLIN. NORTH AMERICA 43:577-596 (June) 1963. 9. Rader, L. E., Jr., Keith, H. B., and Campbell, G. S.: Mechanism of hypotension following release of abdominal aortic clamps. S. Forum 12:265-267, 1961.