Postgraduate Medicine
ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20
Preventing postoperative medical complications David Michael Elnicki MD & William Thomas Shockcor MD To cite this article: David Michael Elnicki MD & William Thomas Shockcor MD (1992) Preventing postoperative medical complications, Postgraduate Medicine, 92:3, 189-202, DOI: 10.1080/00325481.1992.11701449 To link to this article: http://dx.doi.org/10.1080/00325481.1992.11701449
Published online: 17 May 2016.
Submit your article to this journal
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ipgm20 Download by: [Monash University Library]
Date: 03 July 2016, At: 05:04
---@CME credit article
Preventing postoperative medical complications How primary care physicians can help
David Michael Elnicki, MD
William Thomas Shockcor, MD
Downloaded by [Monash University Library] at 05:04 03 July 2016
Preview Just as your concern for your patients' welfare does not stop at the operating room door, neither does your opportunity to improve their prognosis. Drs Elnicki and Shockcor believe that primary care physicians have a unique role in total patient care. In this article, they discuss prevention of major postoperative complications and recommend ways primary care physicians can help optimize their patients' perioperative status.
Primary care physicians have a unique role in the management of patients who are undergoing surgery. They have the benefit of knowing their patients' medical comorbidity, and often they have witnessed patients recover from previous operations. Most important, they will continue to provide comprehensive, long-term care for these patients. Therefore, primary care physicians have a crucial role in optimizing patients' preoperative and postoperative status. We at the general internal medicine consultation service of West Virginia University School of Medicine are often asked to perform preoperative evaluations and assist with postoperative care. We inform students and house staff members that our goals are to predict and prevent perioperative medical complications. Cooperation among the surgical, anesthesiology, nursing,
and medical services is necessary for optimal management. Areas of responsibility are discussed in advance so that each service understands its role in the total care of the patient. Several reviews have examined perioperative issues using an organ-based, comorbidity approach (eg, complications in surgical patients with heart disease).12 In this article, we approach these issues by focusing on prevention of some of the major postoperative complications.
Myocardial infarction Cardiac complications are the most lethal, accounting for one third of postoperative deaths. 3 A number of risk factors for cardiac complications have been identified and validated (table 1). 3-5 Interestingly, some of the variables that predict future development of coronary artery disease (eg, smoking, hyperlipidemia, dia-
VOL 92/NO 3/SEPTEMBER 1. 1992/POSTGRADUATE MEDICINE • POSTOPERATIVE COMPLICATIONS
betes, peripheral atherosclerosis) are not predictive of postoperative cardiac problems. 3 Patients with known coronary artery disease should continue receiving their usual antianginal medications perioperatively with as little interruption as possible. Agents from all of the major cardiovascular drug classes (ie, nitrates, beta blockers, calcium channel blockers) can now be given parenterally, if necessary. Increased demands on the myocardium should be kept to a minimum. Fluid overload, volume depletion, and hypoxemia should be avoided, particularly during the first 5 postoperative days, when patients are at highest risk. Myocardial ischemia often presents atypically after surgery, so a high index of suspicion should be maintained for various signs and symptoms, including dyspnea, confusion, hypertension, and hypotension. Patients with mild stable angina (New York Heart Association [NYHA] class 2) usually tolerate surgery well. Those with class 3 or class 4 angina should be evaluated further with stress testing or angiography. Patients at high risk for coronary artery disease, such as those undergoing aortic aneurysm repair, often receive a more intensive preoperative evalcontinued
189
Elective surgery should be delayed for 6 months after myocardial infarction, when risk of recurrence is reduced.
Downloaded by [Monash University Library] at 05:04 03 July 2016
Table 1. Risk factors for postoperative cardiac complications History Age over 70 yr Myocardial infarction within previous 6 mo Physical findings Third heart sound Jugular venous distention Valvular aortic stenosis Poor general medical condition Laboratory results Elevated aspartate aminotransferase (SGOT) level, creatinine level, and Pco2 Low potassium level, bicarbonate level, and Po 2 Electrocardiographic findings of more than 5 ventricular premature beats/min, rhythm other than sinus rhythm, and/or atrial premature beats Type of operation Aortic Intrathoracic Intraperitoneal Emergent
uation than does the general surgical population. The risk of postoperative myocardial infarction in the general population is less than 1%. Patients who have surgery within 3 months after a myocardial infarction have a 30% chance of having another infarction. The risk drops to 15% for patients having surgery 3 to 6 months after an infarction and plateaus at about 5% at 6 months and there-
190
after. 6 Patients with left ventricular dysfunction or evidence of continued ischemia are probably at even higher risk. Therefore, elective surgery should be delayed for 6 months after myocardial infarction. Sometimes, patients with no past history of coronary artery disease have an abnormal preoperative electrocardiogram. If previous infarction is suspected, it is advisable to delay operation
at least 3 months, until the patient is out of the highest risk period. Because the infarction is likely to have been silent, myocardial assessment (eg, by exercise testing in conjunction with thallium 20 1 scintigraphy or by angiography) is also advisable. Congestive heart failure Patients with NYHA class 3 or class 4 heart failure and patients with a past history of pulmonary edema are at greatest risk for postoperative heart failure. Patients with valvular heart disease often have some degree of ventricular dysfunction; of the valvular lesions, aortic stenosis has the greatest hemodynamic effect. 7 About 20% of patients with aortic stenosis have clinically significant exacerbations of heart failure postoperatively. Therefore, such signs as the typical murmur (harsh, systolic, radiating to the carotid arteries) and a soft, delayed pulse (pulsus parvus et tardus) should prompt further evaluation with echocardiography. Despite a lack of good prospective data, general opinion is that patients with myocardial dysfunction have a better prognosis if their heart failure is controlled preoperatively. Treatment with vasodilators, digoxin
POSTOPERATIVE COMPLICATIONS • VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE
Downloaded by [Monash University Library] at 05:04 03 July 2016
Patients experiencing intraoperative hypertension or hypotension are at risk for postoperative cardiac and renal complications.
(Lanoxicaps, Lanoxin), and angiotensin-converting enzyme inhibitors should be continued perioperatively. Diuretics must be used judiciously, because intraoperative hypotension may develop in patients with depleted intravascular volume. For patients with severe cardiac dysfunction, perioperative hemodynamic monitoring is often performed through a Swan-Ganz catheter. Several commonly used inhalation anesthetics (eg, halothane [Fluothane], enflurane, and isoflurane) produce dosedependent myocardial depression, which may become more pronounced in patients who have preexisting left ventricular dysfunction or intravascular volume depletion. 6 Anesthesiologists often give benwdiazepines, narcotics, or nitrous oxide to minimize negative inotropic effects in patients with cardiac compromise and so should be made aware of patients considered to be at highest risk. Postoperative pulmonary edema has two high-incidence periods. The first, which occurs a half hour to 1 hour postoperatively, may be due to fluids given intraoperatively, use of anesthetic agents, blood pressure fluctuation, or the removal of ventila-
tory support. The second, occurring 24 to 48 hours later, is usually caused by the mobilization of fluids. Patients who have postoperative pulmonary edema require further evaluation for myocardial ischemia.
Hypertension and hypotension Goldman and Caldera8 demonstrated that stable hypertension with diastolic blood pressures of less than 110 mm Hg is not an independent risk factor for postoperative cardiac complications. Hypertensive patients often have perioperative fluctuations in blood pressure, and tight preoperative control does not affect this phenomenon. 8 Patients experiencing intraoperative hypertension or hypotension are at risk for postoperative cardiac and renal complications. 8'9 Hypertensive patients at greatest risk for perioperative blood pressure fluctuations have the following characteristics: low plasma volume, decreased exercise capacity, and advanced age (>70 years). 9 Only low plasma volume is amenable to treatment before surgery. Intraoperative blood pressure control is the responsibility of the anesthesiologist, but the primary care physician needs to be involved in optimizing patients'
preoperative status. In hypertensive patients undergoing elective surgery, preoperative evaluation should focus on the recent course of the hypertension, the side effects of therapy, and any comorbid diseases associated with hypertension (eg, coronary artery disease, cerebrovascular disease, renal compromise). Recent loss of blood pressure control is of concern and should prompt investigation. Symptoms or physical signs consistent with cerebral or cardiac ischemia may also warrant evaluation, depending on the urgency of the operation planned. A cerebral transient ischemic episode should be pursued with the same vigor as unstable angina. 10 Laboratory evidence of end-organ damage may be found by measuring serum creatinine levels and obtaining a urinalysis and electrocardiogram. Serum electrolyte levels should be measured preoperatively, particularly in patients taking diuretics. Hypokalemia and hyponatremia should be corrected to reduce risk of postoperative morbidity. There is general agreement today that treatment with antihypertensive drugs, with the possible exception of diuretics, should be continued peri operatively with
continued
VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE • POSTOPERATIVE COMPLICATIONS
191
The perioperative period provides a unique opportunity for primary care physicians to help patients quit smoking.
Downloaded by [Monash University Library] at 05:04 03 July 2016
Table 2. Findings associated with increased incidence of postoperative pulmonary complications Pco2 greater than 45 mm Hg Ratio of forced expiratory volume in 1 sec to forced vital capacity less than 70% Maximal ventilatory volume less than 50% of predicted value Forced expiratory volume in 1 sec or forced vital capacity less than 50% of predicted value
as little interruption as possible. Rebound increases in blood pressure from sudden discontinuation of therapy with such drugs as beta blockers and clonidine hydrochloride (Catapres) must be avoided. Diuretics are generally withheld 1 to 2 days before surgery to avoid intravascular volume depletion. Like antianginal medications, most antihypertensive agents can now be given parenterally.
Pneumonia and COPD exacerbations Pneumonia and exacerbations of chronic obstructive pulmonary disease (COPD) are common and potentially serious postoperative complications. Factors that increase risk of complications include smoking, obesity, older age
192
(>70 years), presence ofCOPD, thoracic or upper abdominal operations, and use of narcotics or sedatives. 11 Presence of one or more of these factors warrants further noninvasive testing, specifically, chest film, arterial blood gas studies with the patient breathing room air, spirometry, and electrocardiography. Findings that indicate an increased risk of postoperative pulmonary complications are listed in table 2. Interestingly, hypoxemia is not a reliable predictor, and there is no clear difference in risk with use of general anesthesia or spinal anesthesia.11 Helping patients to stop smoking is one of the most important healthcare interventions. The perioperative period provides a unique opportunity to do
so, because the patient will be in a controlled environment for some time, there are good shortterm reasons to quit, and previous illusions of immortality are likely to be shaken in the face of surgery. Smoking cessation at any time before surgery reduces pulmonary complications, bur patients must quit at least 2 months before the operation to receive maximum benefit. 12 A number of measures have been shown to reduce postoperative pulmonary complications in high-risk patients. 13 The respiratory service can teach incentive spirometry and perform chest physical therapy before and after surgery. The patient's usual regimen of pulmonary medications should be continued without interruption. Patients with reversible bronchospasm may be given bronchodilators, and those with evidence of bacterial infection (eg, purulent sputum) may be treated with antibiotics perioperatively. Narcotics diminish sighing and coughing, so their use should be minimized in highrisk patients. Obese patients should be encouraged to lose weight before undergoing surgery, because a loss of even 10 to 20 kg (22 to 44lb) can improve pulmonary status. 11
POSTOPERATIVE COMPLICATIONS • VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE
Downloaded by [Monash University Library] at 05:04 03 July 2016
In diabetic patients, preoperative evaluation should be directed toward cardiac risk factors and an electrocardiogram should always be obtained.
Loss of diabetic control It has long been recognized that diabetic patients have more postoperative complications than other patients. Their wounds heal with more difficulty and are more likely to become infected. Experimental data on leukocyte function and hyperglycemia, as well as clinical outcomes, demonstrate the importance of maintaining diabetic control perioperatively.J4.J5 Constructing a sound perioperative regimen for diabetic patients requires a considerable degree of individualization. Consideration should be given to preoperative glycemic control and the nature of the planned procedure. Glycosylated hemoglobin (HbA1J values provide accurate assessment of glycemic control during the preceding 1 to 2 months. Preoperative evaluation should also include assessment of end-organ damage from diabetes. Physical examination can reveal peripheral and autonomic neuropathy. Degree of nephropathy is assessed by measuring serum electrolyte and creatinine levels and performing a urinalysis; drug doses may need to be adjusted accordingly. Because of the high incidence of cardiac disease in diabetic patients, history taking
David Michael Elnicki, MD William Thomas Shockcor, MD Drs Elnicki (left) and Shockcor (right) are assistant professors of medicine, department of medicine, West Virginia University School of Medicine, Morgantown. They share research interests in perioperative medical evaluation (particularly in geriatric patients) and in assessing the way medical students acquire clinical skills.
and physical examination should be directed toward cardiac risk factors and an electrocardiogram should always be obtained preoperatively. Although perioperative hyperglycemia should be avoided, hypoglycemia in an anesthetized patient is potentially more disastrous. Patients who have been given a hypoglycemic agent,
whether insulin or an oral agent, need to have a continuous supply of intravenous glucose until they are fully awake and eating. There can be no gaps in glucose monitoring after the patient leaves the operating room. Blood glucose levels should be checked on arrival in the recovery room and in the ward room and every 4 to 6 hours thereafter. Patients receiv-
continued
VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE • POSTOPERATIVE COMPLICATIONS
193
Most patients with type I diabetes who undergo surgical procedures require constant insulin infusion.
Downloaded by [Monash University Library] at 05:04 03 July 2016
Table 3. Perioperative management of diabetic patients Type of condition
Management
Insulin-dependent (type I) or unstable non-insulin-dependent (type II)
Start constant insulin (regular) infusion (0.5-1 U/hr) and intravenous dextrose on evening before surgery
Stable but requiring insulin
Give about half intermediateacting insulin (NPH or lente) dose before surgery Administer intravenous dextrose before, during, and after surgery
Diet -controlled
Monitor postoperative blood glucose levels
Controlled with oral agent
Withhold usual regimen on day of surgery Start intravenous dextrose on morning of surgery
ing intravenous insulin drips require more frequent monitoring perioperatively (ie, every half hour to 2 hours). Intravenous boluses of insulin should not be used routinely because of the short biologic half-life (about 20 minutes). Drastic decreases in insulin requirement should be anticipated after such operations as draining of an abscess, cesarean section, and amputation of a gangrenous extremity. The pathophysiology of the
patient's diabetic condition should be a consideration in planning the perioperative regimen (table 3). Insulin-dependent (type I) diabetes reflects the inability to produce insulin, and a steady supply of insulin is needed to prevent ketosis. Diabetic ketoacidosis can occur without tremendously high blood glucose levels and should be assessed in ketosis-prone patients. Most patients with type I diabetes who undergo surgical procedures re-
quire constant insulin infusion. 16 Patients who require insulin but have good glycemic control and who are undergoing relatively minor surgery may be adequately managed if a portion of their intermediate-acting insulin (NPH or lente) is given subcutaneously before the operation and intravenous dextrose is given during surgery. Patients whose diabetes is controlled by diet or oral hypoglycemic agents usually require only close postoperative glucose monitoring, with insulin coverage given when blood glucose levels rise. Although oral agents are generally withheld on the day of surgery, patients who have been taking them need to be given a steady glucose supply, because these agents have long active half-lives.
Addisonian crisis In the perioperative period, the body's usual output of corticosteroids is increased sevenfold. A patient who is hypoadrenal from any cause cannot meet this increased demand and may be prone to postoperative shock. The adequacy of the pituitaryadrenal axis should be suspected in patients with preoperative characteristics of either adrenocortical excess or insufficiency.
continued
194
POSTOPERATIVE COMPLICATIONS • VOL 92/NO 3/SEPTEMBER 1. 1992/POSTGRADUATE MEDICINE
OuinidexExtentabs. qu1n1d1r:e sulfate extended-release tablets USP 300
rlQ
Trost experience. The follOwing 1S a bnef summary onty Before prescr1b1ng see complete prescflblng 1nformat,on 1n Oum1del prOCiuct label1ng
ContrlindlcltioM.Intra.,·entrlcular concluct,on defects Complete A-V blocK A-V con duC!10n disorders caused by 01Q1!ahs 1ntox,cat10n Aberrant •mpulses and abnormal rhythmsduetoescape 'Tl€Chan1sms ldiOS'tncracyorhypersens'llvltytoqulnldmeor
related Clnchonadenvat,ves Myasthenia grav1s
Wlminos: In the treatment ot atnal tlufter revers1on to S1nus rhythm may be preceded by a prOQress1ve reOucMn 1n the deoree of A-V bloclo:. to a 11 rat10 resultmg 1n an
Downloaded by [Monash University Library] at 05:04 03 July 2016
extremely rap10 ventriCular rate Th1s poss1ble hazard may be reduced by dlgrtal,zaliOn
pr,ortoadmlnlstra!IOnolqUinldme Reports 1n the 111erature 1nd 1cate that serum concentrat1ons ot diQOxm may 1ncrease and may even double when Qu1n1d1ne 1Sadmtn1steredconcurrently Pat1entson con· com1tant therapy should be carefully monitored tor diQitahs tox1C1ty Reduchon of diQOxm dosage may have to be cons1dered Manllesta!IOns ot Qu1n1dtne card10tox1C1ty such as excess1ve protongat1on of the OT 1ntervat w1denmg ot the DRS complex and ventocular tachyarrhythm1as mandate ,mmedlated,scon!lnuat,on of the drug andtorctosecltniCaland electrocardiOQraphiC moMor1ng In susceptible 1nd1V1dua1s such as those w1th marg1na11y compensated cardiOvascular 01sease qum1dme may produce clin1cally 1mportant e1epress1on of card1ac tunct on man1fested by hypotens1on bradycardia or heartbloc~o:. Du1n1d1ne therapy shou1d be carefully monitored m such 1nd1vtduals Ou1MMe should be used w1th extreme caut1on 1n pat1ents w1!h mcomplete AV bloc~ s1nce complete AV bloc~~:. ar~d asystole may be prodtJCed Ou1n1dlne may cause abner malit1es of care11ac rhythm 111 d1Q1tai1Zed pat1er~ts and thereto1e should be used Wll!"l caut1on m the presence of dlg1talls 111IOx1Cal10n Du1111dtne should be used w1th cau110n 1n pat1ents exhlbdtng renal card1ac or hepatiC msuH1c1ency because of potent,al accumulat10n of qum1d1ne 111 serum leadmg to tOXICity Pat1ents taktng QU1111dll1e occas1onally have syncopal ep1sodes wh1ch usually result from ventr~cular tachycardia or l1bllllat10n Th1s syndrome has not been shOwn to be re 1ated to dose or serum 1eve1s Syncopal ep1sodes frequently term1nate sponta1eous1y o· '" response to treatmer~t but somet1mes are tata1 Cases ot hepatotoxiCIIJ· 1ncludtnQ granulomatous hepat1t1s due to QUinldme hyper sensi\IVIIY have been reported Unexplained lever and/or e1evat1on of hepat1c erzymes partiCularly 1n the early stages ot therapy warrant cons,derat1on of poss1ble hepatotox 1C1!y MoMormg 11ver tunct1on Our1ng the f1rst 4 8 weeks snould be considered Cessat,onofQulnldmelnthesecasesusuallyresultsll1theO,sappearanceoftOxiCIIY PrecarUons: General-All the precaut1ons applymgto regular qutn1dme therapy apply to tl11s product Hypersersi!IVI!y or anaphylactOid reacliOns to Qu1n1d1ne althOugh rare should be cons1dered espec1ally duong the f1rst weeks of therapy Hospttalizat1on tor close clm1ca1 observat10n electrocardiOQraphiC montto11nQ and determtnaliOn ot serum qum1dtne levels are mdtcated when large doses of Qt..tn1d1ne are used or wtlh pattents who present an tncreasell r1sk Information for Pat1ents -As w1th all solid dosage rted1Cat1ons DU1n1dex Extertabs shOuld be ta1r.en w1th an adequate amount ofllu1d preferably w1th the patten! 1n an upr1ght pos1t10n to tac111tate swallowtng They should be swallowed whole 1n order to preser.ethecontrolled·re1easemechan1sm LabOratory Tests-Per1od1C blood counts and liver and ktdney funct1on tests Should be performed dur1ng long· term therapy the drug should be d1Scon!lnued 11 blood Clyscrastas or ev1dence of hepatiC or renal dystunct1on occurs Drug lnteracMns Effoct Dnll DU1n1d1ne With antiChOlinergiC arugs Add1t1ve vagolyi1C el!ect DU1n1d1ne w11t1 chOI1nerg1C drugs Antagon1smofcMimerg1cettects Al~alm1zat10n o~ ur111e DU1n1dmew1tt1 cartxJn1c anhy resullmglndecreased drase 1nh1bi!Ors sod1um brcart>onatettHaz,dediUfe!ICS excret1on of Qu1n1d1ne Du1n1dmewtlhcoumar1n ReducliOn of clot!lng anticoagulants factorconcentrat1ons DU1n1d1ne w1th tut>ocurare Potent1at10n of neuro suwnylcl"loline and muscular blocl
ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20
Preventing postoperative medical complications David Michael Elnicki MD & William Thomas Shockcor MD To cite this article: David Michael Elnicki MD & William Thomas Shockcor MD (1992) Preventing postoperative medical complications, Postgraduate Medicine, 92:3, 189-202, DOI: 10.1080/00325481.1992.11701449 To link to this article: http://dx.doi.org/10.1080/00325481.1992.11701449
Published online: 17 May 2016.
Submit your article to this journal
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ipgm20 Download by: [Monash University Library]
Date: 03 July 2016, At: 05:04
---@CME credit article
Preventing postoperative medical complications How primary care physicians can help
David Michael Elnicki, MD
William Thomas Shockcor, MD
Downloaded by [Monash University Library] at 05:04 03 July 2016
Preview Just as your concern for your patients' welfare does not stop at the operating room door, neither does your opportunity to improve their prognosis. Drs Elnicki and Shockcor believe that primary care physicians have a unique role in total patient care. In this article, they discuss prevention of major postoperative complications and recommend ways primary care physicians can help optimize their patients' perioperative status.
Primary care physicians have a unique role in the management of patients who are undergoing surgery. They have the benefit of knowing their patients' medical comorbidity, and often they have witnessed patients recover from previous operations. Most important, they will continue to provide comprehensive, long-term care for these patients. Therefore, primary care physicians have a crucial role in optimizing patients' preoperative and postoperative status. We at the general internal medicine consultation service of West Virginia University School of Medicine are often asked to perform preoperative evaluations and assist with postoperative care. We inform students and house staff members that our goals are to predict and prevent perioperative medical complications. Cooperation among the surgical, anesthesiology, nursing,
and medical services is necessary for optimal management. Areas of responsibility are discussed in advance so that each service understands its role in the total care of the patient. Several reviews have examined perioperative issues using an organ-based, comorbidity approach (eg, complications in surgical patients with heart disease).12 In this article, we approach these issues by focusing on prevention of some of the major postoperative complications.
Myocardial infarction Cardiac complications are the most lethal, accounting for one third of postoperative deaths. 3 A number of risk factors for cardiac complications have been identified and validated (table 1). 3-5 Interestingly, some of the variables that predict future development of coronary artery disease (eg, smoking, hyperlipidemia, dia-
VOL 92/NO 3/SEPTEMBER 1. 1992/POSTGRADUATE MEDICINE • POSTOPERATIVE COMPLICATIONS
betes, peripheral atherosclerosis) are not predictive of postoperative cardiac problems. 3 Patients with known coronary artery disease should continue receiving their usual antianginal medications perioperatively with as little interruption as possible. Agents from all of the major cardiovascular drug classes (ie, nitrates, beta blockers, calcium channel blockers) can now be given parenterally, if necessary. Increased demands on the myocardium should be kept to a minimum. Fluid overload, volume depletion, and hypoxemia should be avoided, particularly during the first 5 postoperative days, when patients are at highest risk. Myocardial ischemia often presents atypically after surgery, so a high index of suspicion should be maintained for various signs and symptoms, including dyspnea, confusion, hypertension, and hypotension. Patients with mild stable angina (New York Heart Association [NYHA] class 2) usually tolerate surgery well. Those with class 3 or class 4 angina should be evaluated further with stress testing or angiography. Patients at high risk for coronary artery disease, such as those undergoing aortic aneurysm repair, often receive a more intensive preoperative evalcontinued
189
Elective surgery should be delayed for 6 months after myocardial infarction, when risk of recurrence is reduced.
Downloaded by [Monash University Library] at 05:04 03 July 2016
Table 1. Risk factors for postoperative cardiac complications History Age over 70 yr Myocardial infarction within previous 6 mo Physical findings Third heart sound Jugular venous distention Valvular aortic stenosis Poor general medical condition Laboratory results Elevated aspartate aminotransferase (SGOT) level, creatinine level, and Pco2 Low potassium level, bicarbonate level, and Po 2 Electrocardiographic findings of more than 5 ventricular premature beats/min, rhythm other than sinus rhythm, and/or atrial premature beats Type of operation Aortic Intrathoracic Intraperitoneal Emergent
uation than does the general surgical population. The risk of postoperative myocardial infarction in the general population is less than 1%. Patients who have surgery within 3 months after a myocardial infarction have a 30% chance of having another infarction. The risk drops to 15% for patients having surgery 3 to 6 months after an infarction and plateaus at about 5% at 6 months and there-
190
after. 6 Patients with left ventricular dysfunction or evidence of continued ischemia are probably at even higher risk. Therefore, elective surgery should be delayed for 6 months after myocardial infarction. Sometimes, patients with no past history of coronary artery disease have an abnormal preoperative electrocardiogram. If previous infarction is suspected, it is advisable to delay operation
at least 3 months, until the patient is out of the highest risk period. Because the infarction is likely to have been silent, myocardial assessment (eg, by exercise testing in conjunction with thallium 20 1 scintigraphy or by angiography) is also advisable. Congestive heart failure Patients with NYHA class 3 or class 4 heart failure and patients with a past history of pulmonary edema are at greatest risk for postoperative heart failure. Patients with valvular heart disease often have some degree of ventricular dysfunction; of the valvular lesions, aortic stenosis has the greatest hemodynamic effect. 7 About 20% of patients with aortic stenosis have clinically significant exacerbations of heart failure postoperatively. Therefore, such signs as the typical murmur (harsh, systolic, radiating to the carotid arteries) and a soft, delayed pulse (pulsus parvus et tardus) should prompt further evaluation with echocardiography. Despite a lack of good prospective data, general opinion is that patients with myocardial dysfunction have a better prognosis if their heart failure is controlled preoperatively. Treatment with vasodilators, digoxin
POSTOPERATIVE COMPLICATIONS • VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE
Downloaded by [Monash University Library] at 05:04 03 July 2016
Patients experiencing intraoperative hypertension or hypotension are at risk for postoperative cardiac and renal complications.
(Lanoxicaps, Lanoxin), and angiotensin-converting enzyme inhibitors should be continued perioperatively. Diuretics must be used judiciously, because intraoperative hypotension may develop in patients with depleted intravascular volume. For patients with severe cardiac dysfunction, perioperative hemodynamic monitoring is often performed through a Swan-Ganz catheter. Several commonly used inhalation anesthetics (eg, halothane [Fluothane], enflurane, and isoflurane) produce dosedependent myocardial depression, which may become more pronounced in patients who have preexisting left ventricular dysfunction or intravascular volume depletion. 6 Anesthesiologists often give benwdiazepines, narcotics, or nitrous oxide to minimize negative inotropic effects in patients with cardiac compromise and so should be made aware of patients considered to be at highest risk. Postoperative pulmonary edema has two high-incidence periods. The first, which occurs a half hour to 1 hour postoperatively, may be due to fluids given intraoperatively, use of anesthetic agents, blood pressure fluctuation, or the removal of ventila-
tory support. The second, occurring 24 to 48 hours later, is usually caused by the mobilization of fluids. Patients who have postoperative pulmonary edema require further evaluation for myocardial ischemia.
Hypertension and hypotension Goldman and Caldera8 demonstrated that stable hypertension with diastolic blood pressures of less than 110 mm Hg is not an independent risk factor for postoperative cardiac complications. Hypertensive patients often have perioperative fluctuations in blood pressure, and tight preoperative control does not affect this phenomenon. 8 Patients experiencing intraoperative hypertension or hypotension are at risk for postoperative cardiac and renal complications. 8'9 Hypertensive patients at greatest risk for perioperative blood pressure fluctuations have the following characteristics: low plasma volume, decreased exercise capacity, and advanced age (>70 years). 9 Only low plasma volume is amenable to treatment before surgery. Intraoperative blood pressure control is the responsibility of the anesthesiologist, but the primary care physician needs to be involved in optimizing patients'
preoperative status. In hypertensive patients undergoing elective surgery, preoperative evaluation should focus on the recent course of the hypertension, the side effects of therapy, and any comorbid diseases associated with hypertension (eg, coronary artery disease, cerebrovascular disease, renal compromise). Recent loss of blood pressure control is of concern and should prompt investigation. Symptoms or physical signs consistent with cerebral or cardiac ischemia may also warrant evaluation, depending on the urgency of the operation planned. A cerebral transient ischemic episode should be pursued with the same vigor as unstable angina. 10 Laboratory evidence of end-organ damage may be found by measuring serum creatinine levels and obtaining a urinalysis and electrocardiogram. Serum electrolyte levels should be measured preoperatively, particularly in patients taking diuretics. Hypokalemia and hyponatremia should be corrected to reduce risk of postoperative morbidity. There is general agreement today that treatment with antihypertensive drugs, with the possible exception of diuretics, should be continued peri operatively with
continued
VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE • POSTOPERATIVE COMPLICATIONS
191
The perioperative period provides a unique opportunity for primary care physicians to help patients quit smoking.
Downloaded by [Monash University Library] at 05:04 03 July 2016
Table 2. Findings associated with increased incidence of postoperative pulmonary complications Pco2 greater than 45 mm Hg Ratio of forced expiratory volume in 1 sec to forced vital capacity less than 70% Maximal ventilatory volume less than 50% of predicted value Forced expiratory volume in 1 sec or forced vital capacity less than 50% of predicted value
as little interruption as possible. Rebound increases in blood pressure from sudden discontinuation of therapy with such drugs as beta blockers and clonidine hydrochloride (Catapres) must be avoided. Diuretics are generally withheld 1 to 2 days before surgery to avoid intravascular volume depletion. Like antianginal medications, most antihypertensive agents can now be given parenterally.
Pneumonia and COPD exacerbations Pneumonia and exacerbations of chronic obstructive pulmonary disease (COPD) are common and potentially serious postoperative complications. Factors that increase risk of complications include smoking, obesity, older age
192
(>70 years), presence ofCOPD, thoracic or upper abdominal operations, and use of narcotics or sedatives. 11 Presence of one or more of these factors warrants further noninvasive testing, specifically, chest film, arterial blood gas studies with the patient breathing room air, spirometry, and electrocardiography. Findings that indicate an increased risk of postoperative pulmonary complications are listed in table 2. Interestingly, hypoxemia is not a reliable predictor, and there is no clear difference in risk with use of general anesthesia or spinal anesthesia.11 Helping patients to stop smoking is one of the most important healthcare interventions. The perioperative period provides a unique opportunity to do
so, because the patient will be in a controlled environment for some time, there are good shortterm reasons to quit, and previous illusions of immortality are likely to be shaken in the face of surgery. Smoking cessation at any time before surgery reduces pulmonary complications, bur patients must quit at least 2 months before the operation to receive maximum benefit. 12 A number of measures have been shown to reduce postoperative pulmonary complications in high-risk patients. 13 The respiratory service can teach incentive spirometry and perform chest physical therapy before and after surgery. The patient's usual regimen of pulmonary medications should be continued without interruption. Patients with reversible bronchospasm may be given bronchodilators, and those with evidence of bacterial infection (eg, purulent sputum) may be treated with antibiotics perioperatively. Narcotics diminish sighing and coughing, so their use should be minimized in highrisk patients. Obese patients should be encouraged to lose weight before undergoing surgery, because a loss of even 10 to 20 kg (22 to 44lb) can improve pulmonary status. 11
POSTOPERATIVE COMPLICATIONS • VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE
Downloaded by [Monash University Library] at 05:04 03 July 2016
In diabetic patients, preoperative evaluation should be directed toward cardiac risk factors and an electrocardiogram should always be obtained.
Loss of diabetic control It has long been recognized that diabetic patients have more postoperative complications than other patients. Their wounds heal with more difficulty and are more likely to become infected. Experimental data on leukocyte function and hyperglycemia, as well as clinical outcomes, demonstrate the importance of maintaining diabetic control perioperatively.J4.J5 Constructing a sound perioperative regimen for diabetic patients requires a considerable degree of individualization. Consideration should be given to preoperative glycemic control and the nature of the planned procedure. Glycosylated hemoglobin (HbA1J values provide accurate assessment of glycemic control during the preceding 1 to 2 months. Preoperative evaluation should also include assessment of end-organ damage from diabetes. Physical examination can reveal peripheral and autonomic neuropathy. Degree of nephropathy is assessed by measuring serum electrolyte and creatinine levels and performing a urinalysis; drug doses may need to be adjusted accordingly. Because of the high incidence of cardiac disease in diabetic patients, history taking
David Michael Elnicki, MD William Thomas Shockcor, MD Drs Elnicki (left) and Shockcor (right) are assistant professors of medicine, department of medicine, West Virginia University School of Medicine, Morgantown. They share research interests in perioperative medical evaluation (particularly in geriatric patients) and in assessing the way medical students acquire clinical skills.
and physical examination should be directed toward cardiac risk factors and an electrocardiogram should always be obtained preoperatively. Although perioperative hyperglycemia should be avoided, hypoglycemia in an anesthetized patient is potentially more disastrous. Patients who have been given a hypoglycemic agent,
whether insulin or an oral agent, need to have a continuous supply of intravenous glucose until they are fully awake and eating. There can be no gaps in glucose monitoring after the patient leaves the operating room. Blood glucose levels should be checked on arrival in the recovery room and in the ward room and every 4 to 6 hours thereafter. Patients receiv-
continued
VOL 92/NO 3/SEPTEMBER 1, 1992/POSTGRADUATE MEDICINE • POSTOPERATIVE COMPLICATIONS
193
Most patients with type I diabetes who undergo surgical procedures require constant insulin infusion.
Downloaded by [Monash University Library] at 05:04 03 July 2016
Table 3. Perioperative management of diabetic patients Type of condition
Management
Insulin-dependent (type I) or unstable non-insulin-dependent (type II)
Start constant insulin (regular) infusion (0.5-1 U/hr) and intravenous dextrose on evening before surgery
Stable but requiring insulin
Give about half intermediateacting insulin (NPH or lente) dose before surgery Administer intravenous dextrose before, during, and after surgery
Diet -controlled
Monitor postoperative blood glucose levels
Controlled with oral agent
Withhold usual regimen on day of surgery Start intravenous dextrose on morning of surgery
ing intravenous insulin drips require more frequent monitoring perioperatively (ie, every half hour to 2 hours). Intravenous boluses of insulin should not be used routinely because of the short biologic half-life (about 20 minutes). Drastic decreases in insulin requirement should be anticipated after such operations as draining of an abscess, cesarean section, and amputation of a gangrenous extremity. The pathophysiology of the
patient's diabetic condition should be a consideration in planning the perioperative regimen (table 3). Insulin-dependent (type I) diabetes reflects the inability to produce insulin, and a steady supply of insulin is needed to prevent ketosis. Diabetic ketoacidosis can occur without tremendously high blood glucose levels and should be assessed in ketosis-prone patients. Most patients with type I diabetes who undergo surgical procedures re-
quire constant insulin infusion. 16 Patients who require insulin but have good glycemic control and who are undergoing relatively minor surgery may be adequately managed if a portion of their intermediate-acting insulin (NPH or lente) is given subcutaneously before the operation and intravenous dextrose is given during surgery. Patients whose diabetes is controlled by diet or oral hypoglycemic agents usually require only close postoperative glucose monitoring, with insulin coverage given when blood glucose levels rise. Although oral agents are generally withheld on the day of surgery, patients who have been taking them need to be given a steady glucose supply, because these agents have long active half-lives.
Addisonian crisis In the perioperative period, the body's usual output of corticosteroids is increased sevenfold. A patient who is hypoadrenal from any cause cannot meet this increased demand and may be prone to postoperative shock. The adequacy of the pituitaryadrenal axis should be suspected in patients with preoperative characteristics of either adrenocortical excess or insufficiency.
continued
194
POSTOPERATIVE COMPLICATIONS • VOL 92/NO 3/SEPTEMBER 1. 1992/POSTGRADUATE MEDICINE
OuinidexExtentabs. qu1n1d1r:e sulfate extended-release tablets USP 300
rlQ
Trost experience. The follOwing 1S a bnef summary onty Before prescr1b1ng see complete prescflblng 1nformat,on 1n Oum1del prOCiuct label1ng
ContrlindlcltioM.Intra.,·entrlcular concluct,on defects Complete A-V blocK A-V con duC!10n disorders caused by 01Q1!ahs 1ntox,cat10n Aberrant •mpulses and abnormal rhythmsduetoescape 'Tl€Chan1sms ldiOS'tncracyorhypersens'llvltytoqulnldmeor
related Clnchonadenvat,ves Myasthenia grav1s
Wlminos: In the treatment ot atnal tlufter revers1on to S1nus rhythm may be preceded by a prOQress1ve reOucMn 1n the deoree of A-V bloclo:. to a 11 rat10 resultmg 1n an
Downloaded by [Monash University Library] at 05:04 03 July 2016
extremely rap10 ventriCular rate Th1s poss1ble hazard may be reduced by dlgrtal,zaliOn
pr,ortoadmlnlstra!IOnolqUinldme Reports 1n the 111erature 1nd 1cate that serum concentrat1ons ot diQOxm may 1ncrease and may even double when Qu1n1d1ne 1Sadmtn1steredconcurrently Pat1entson con· com1tant therapy should be carefully monitored tor diQitahs tox1C1ty Reduchon of diQOxm dosage may have to be cons1dered Manllesta!IOns ot Qu1n1dtne card10tox1C1ty such as excess1ve protongat1on of the OT 1ntervat w1denmg ot the DRS complex and ventocular tachyarrhythm1as mandate ,mmedlated,scon!lnuat,on of the drug andtorctosecltniCaland electrocardiOQraphiC moMor1ng In susceptible 1nd1V1dua1s such as those w1th marg1na11y compensated cardiOvascular 01sease qum1dme may produce clin1cally 1mportant e1epress1on of card1ac tunct on man1fested by hypotens1on bradycardia or heartbloc~o:. Du1n1d1ne therapy shou1d be carefully monitored m such 1nd1vtduals Ou1MMe should be used w1th extreme caut1on 1n pat1ents w1!h mcomplete AV bloc~ s1nce complete AV bloc~~:. ar~d asystole may be prodtJCed Ou1n1dlne may cause abner malit1es of care11ac rhythm 111 d1Q1tai1Zed pat1er~ts and thereto1e should be used Wll!"l caut1on m the presence of dlg1talls 111IOx1Cal10n Du1111dtne should be used w1th cau110n 1n pat1ents exhlbdtng renal card1ac or hepatiC msuH1c1ency because of potent,al accumulat10n of qum1d1ne 111 serum leadmg to tOXICity Pat1ents taktng QU1111dll1e occas1onally have syncopal ep1sodes wh1ch usually result from ventr~cular tachycardia or l1bllllat10n Th1s syndrome has not been shOwn to be re 1ated to dose or serum 1eve1s Syncopal ep1sodes frequently term1nate sponta1eous1y o· '" response to treatmer~t but somet1mes are tata1 Cases ot hepatotoxiCIIJ· 1ncludtnQ granulomatous hepat1t1s due to QUinldme hyper sensi\IVIIY have been reported Unexplained lever and/or e1evat1on of hepat1c erzymes partiCularly 1n the early stages ot therapy warrant cons,derat1on of poss1ble hepatotox 1C1!y MoMormg 11ver tunct1on Our1ng the f1rst 4 8 weeks snould be considered Cessat,onofQulnldmelnthesecasesusuallyresultsll1theO,sappearanceoftOxiCIIY PrecarUons: General-All the precaut1ons applymgto regular qutn1dme therapy apply to tl11s product Hypersersi!IVI!y or anaphylactOid reacliOns to Qu1n1d1ne althOugh rare should be cons1dered espec1ally duong the f1rst weeks of therapy Hospttalizat1on tor close clm1ca1 observat10n electrocardiOQraphiC montto11nQ and determtnaliOn ot serum qum1dtne levels are mdtcated when large doses of Qt..tn1d1ne are used or wtlh pattents who present an tncreasell r1sk Information for Pat1ents -As w1th all solid dosage rted1Cat1ons DU1n1dex Extertabs shOuld be ta1r.en w1th an adequate amount ofllu1d preferably w1th the patten! 1n an upr1ght pos1t10n to tac111tate swallowtng They should be swallowed whole 1n order to preser.ethecontrolled·re1easemechan1sm LabOratory Tests-Per1od1C blood counts and liver and ktdney funct1on tests Should be performed dur1ng long· term therapy the drug should be d1Scon!lnued 11 blood Clyscrastas or ev1dence of hepatiC or renal dystunct1on occurs Drug lnteracMns Effoct Dnll DU1n1d1ne With antiChOlinergiC arugs Add1t1ve vagolyi1C el!ect DU1n1d1ne w11t1 chOI1nerg1C drugs Antagon1smofcMimerg1cettects Al~alm1zat10n o~ ur111e DU1n1dmew1tt1 cartxJn1c anhy resullmglndecreased drase 1nh1bi!Ors sod1um brcart>onatettHaz,dediUfe!ICS excret1on of Qu1n1d1ne Du1n1dmewtlhcoumar1n ReducliOn of clot!lng anticoagulants factorconcentrat1ons DU1n1d1ne w1th tut>ocurare Potent1at10n of neuro suwnylcl"loline and muscular blocl
