You are in: eMedicine Specialties > Perioperative Care > Perioperative Care Perioperative Management of the Diabetic PatientArticle Last Updated: May 17, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
 
Author: David M Rothenberg, MD, FCCM, Professor, Department of Anesthesiology, Rush Medical College; Associate Dean, Academic Affiliations, Director, Section of Anesthesia-Critical Care, Director, Residency Education, Rush University Medical Center David M Rothenberg is a member of the following medical societies: American Medical Association, American Society of Anesthesiologists, Chicago Medical Society, and Society of Critical Care Medicine Coauthor(s): Mira Loh-Trivedi, PharmD, Clinical Pharmacy Specialist, Surgical Intensive Care Unit, Rush University Medical Center; Benjamin Pace, MD, FACS, Director, Department of Surgery, Queens Hospital Center; Clinical Associate Professor, Department of Surgery, Mount Sinai School of Medicine; Issac Sachmechi, MD, FACP, FACE, Assistant Professor of Medicine, Mount Sinai School of Medicine; Chief of Endocrinology, Mount Sinai Services at Queens Hospital Center Editors: David S Schade, MD, Chief, Division of Endocrinology and Metabolism, Department of Internal Medicine, Professor, University of New Mexico School of Medicine and Health Sciences Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Donna Leco Mercado, MD, Director of Medical Consultation, Department of Internal Medicine, Baystate Medical Center; Assistant Professor, Tufts University School of Medicine; Mark Cooper, MBBS, PhD, FRACP, Head, Diabetes & Metabolism Division, Baker Heart Research Institute, Professor of Medicine, Monash University; William A Schwer, MD, Professor, Department of Family Medicine, Rush Medical College; Chairman, Department of Family Medicine, Rush-Presbyterian-St Luke's Medical Center Author and Editor Disclosure Synonyms and related keywords: type 1 diabetes, type I diabetes, insulin-dependent diabetes, type 2 diabetes, type II diabetes, noninsulin-dependent diabetes, non-insulin-dependent diabetes, non-insulin dependent diabetes, diabetic management, preoperative care and diabetes, postoperative care and diabetes, diabetes and surgery, diabetes mellitus, DB, DM, diabetic surgical care, diabetic surgery, diabetes, diabetic surgical patients INTRODUCTIONSection 2 of 12
 
Diabetes mellitus (DM) is an increasingly common medical condition affecting approximately 7% of the population of the United States. Of these 20 million people, it is estimated that nearly one third are unaware that they have the disease until faced with associated complications. The prevalence is even greater in hospitalized patients. The American Diabetes Association conservatively estimates that 12-25% of hospitalized adult patients have DM. With the increasing prevalence of diabetic patients undergoing surgery, and the increased risk of complications associated with DM, appropriate perioperative assessment and management is imperative. Mortality rates in diabetic patients have been estimated to be up to 5 times greater than in nondiabetic patients, often related to the end-organ damage caused by the disease. Chronic complications resulting in microangiopathy (retinopathy, nephropathy, and neuropathy) and macroangiopathy (atherosclerosis) directly increase the need for surgical intervention and often the occurrence of surgical complications (infections and vasculopathies). Studies have shown that DM is an independent predictor of postoperative myocardial ischemia among patients undergoing cardiac and noncardiac surgery and is likewise an independent predictor of postoperative infectious complications in patients undergoing cardiac surgery. Fortunately, intensive glycemic control has been shown to have a profound effect on reducing the incidence of many of these complications in a variety of surgical populations. Optimal perioperative glycemic control can be achieved through a variety of methods, including the use of closely titrated intravenous insulin. The importance and benefits of intensive glycemic control are well documented and have become a standard of care, particularly in patients who are critically ill, where tight glycemic control has been shown to reduce morbidity and mortality. Although tight glycemic control increases the risk of hypoglycemia and requires increased monitoring, the overall benefits of therapy have been well documented. The ultimate goal in the management of diabetic patients is to achieve equivalent outcomes as those patients without DM. Meta-analysis of 15 studies reported that hyperglycemia (blood glucose >110 mg/dL) increased both in-hospital mortality and incidence of heart failure in patients admitted for acute myocardial infarction, independent of a prior diagnosis of DM, demonstrating that the diagnosis of DM per se is not as important as controlling blood glucose concentrations. Comprehensive preoperative assessment, close monitoring, and intensive intraoperative and postoperative management by a multidisciplinary team are recommended. A strong grasp of the complexities of glucose insulin interrelationship and of the effects of anesthesia and surgery is essential to optimal management and outcomes. PHYSIOLOGY OF GLUCOSE METABOLISMSection 3 of 12
Glucose metabolism is largely a function of the liver, the pancreas, and, to a lesser degree, peripheral tissue. The liver plays a variety of roles in glucose regulation; it extracts glucose and stores it in the form of glycogen and performs gluconeogenesis as well as glycogenolysis. The pancreas secretes counterregulatory hormones: insulin from islet beta cells, which lowers blood glucose concentrations, and glucagon from islet alpha cells, which raises blood glucose concentrations. Additional contributors to glucose metabolism include the catabolic hormones: epinephrine, glucocorticoids, and growth hormone, which all raise blood glucose concentrations. Peripheral tissues participate in glucose metabolism by extracting glucose for energy needs, thus lowering blood glucose levels. Appropriate glucose regulation preserves the availability of glucose to these tissues. For example, in the fasting state, insulin secretion decreases and catabolic hormone levels rise. In the case of absolute insulin deficiency (type 1 DM), unopposed catabolic action leads to hyperglycemia and, eventually, diabetic ketoacidosis. Type 2 DM is characterized by a peripheral resistance to insulin, and, in general, patients are less susceptible to developing ketoacidosis. GENERAL PREOPERATIVE ASSESSMENTSection 4 of 12
The foundation of the preoperative assessment is a comprehensive history and physical examination. Since estimates suggest that one third of diabetic patients are unaware of their disease, it may be prudent to screen all patients undergoing intermediate or major surgery by checking glycosylated hemoglobin (HbA1c). In one study of nondiabetic patients presenting for emergent treatment of soft tissue infections, less than 5% had blood glucose levels >180 mg/dL. In addition to standard preoperative information, the following details of current diabetes management should be documented: duration of treatment, specific medication regimen, and issues with insulin resistance or brittleness. If available, this information will be detailed in the patient's "diabetes journal." The history should assess for symptoms of ischemic cardiac, retinal, renal, neurological, and/or peripheral vascular disease. Since the mortality rate from heart disease is approximately 2-4 times greater than for comparatively matched nondiabetic patients, a comprehensive cardiac history should be completed for patients undergoing intermediate or major noncardiac surgery. In patients undergoing major vascular surgery, this may include either noninvasive myocardial function studies (eg, dobutamine-stress echocardiography) or coronary artery angiography. To summarize, the history should include the following:
The physical examination includes assessment for orthostatic hypotension as a potential sign of autonomic neuropathy. A fundoscopic examination may give insight into the patient's risk of developing postoperative blindness, especially following prolonged spinal surgery in the prone position and cardiac surgery requiring cardiopulmonary bypass. Type 1 DM is associated with a "stiff joint" syndrome, which poses a significant risk during airway management at the time of general anesthesia. Affecting the temporomandibular, atlantooccipital, and other cervical spine joints, these patients also tend to have short stature and waxy skin, related to chronic hyperglycemia and nonenzymatic glycosylation of collagen and its deposition in joints. A positive "prayer sign" can be elicited on examination with the patient unable to approximate the palmar surfaces of the phalangeal joints while pressing their hands together; this represents cervical spine immobility and the potential for a difficult endotracheal intubation (see Media file 1). Further airway evaluation should include assessment of thyroid gland size, as patients with type 1 DM have a 15% association of other autoimmune diseases, such as Hashimoto thyroiditis and Graves disease. Finally, the degree of preoperative neurological dysfunction is important to document, especially prior to regional anesthesia or peripheral nerve blocks, to assess the degree of subsequent nerve injury. To summarize, the physical examination should include the following:
Preoperative laboratory evaluation in all diabetic patients undergoing intermediate or major noncardiac or cardiac surgery should include the following: fasting serum glucose concentration, HbA1c, serum electrolytes, blood urea nitrogen, and creatinine (estimated glomerular filtration rate). In addition, a urinalysis should be performed to assess for proteinuria and microalbuminuria. Studies have shown a correlation between preoperative proteinuria and postoperative death after coronary artery bypass graft surgery, with the mortality rate increasing proportionally with the concentration of protein in the urine. Based on the nature of surgery, electrocardiography assessing R-R interval during respiration may be useful in the evaluation of autonomic neuropathy. (Loss of R-R variability when the heart rate at maximal inspiration is compared with the heart rate at maximal expiration implies the presence of autonomic cardiac neuropathy.) To summarize, the laboratory evaluation should include the following:
GENERAL PREOPERATIVE MANAGEMENTSection 5 of 12
Given that patients present preoperatively with a variety of DM regimens and are scheduled for surgery at varying times of the day, there is no consensus as to the optimal management to maintain euglycemia in the early perioperative phase. However, employing general management strategies to minimize the likelihood of adverse events should govern decision making. On the day of surgery, patients on oral regimens should be advised to discontinue these medications. Secretagogues (eg, sulfonylureas, meglitinides) have the potential to cause hypoglycemia. In addition, sulfonylureas have been associated with interfering with ischemic myocardial preconditioning and may theoretically increase risk of perioperative myocardial ischemia and infarction. Patients taking metformin should be advised to discontinue this drug because of the risk of developing lactic acidosis. For these patients, short-acting insulin may be administered subcutaneously as a sliding scale or as a continuous infusion, if needed, to maintain optimal glucose control, depending on the extent of surgery. Patients who are insulin-dependent (type 1) should be advised to reduce their bedtime dose of insulin the night prior to surgery to prevent hypoglycemia, while nil per os. Maintenance insulin may be continued, based on history of glucose concentrations and the discretion of the advising clinician. Patients may be advised to consult their anesthesiologist and diabetes-managing practitioner for individualized recommendations regarding their situation. Additionally, patients should be monitored periodically preoperatively to assess for hyperglycemia and hypoglycemia. METABOLIC RESPONSE TO ANESTHESIA AND SURGERYSection 6 of 12
Surgery induces a considerable stress response mediated by the neuroendocrine system through the release of catecholamines, glucagon, and cortisol. The principal mechanism lies with the elevation of sympathetic tone with a subsequent release of cortisol and catecholamines during surgery. A nondiabetic patient is able to maintain glucose homeostasis by secreting a corresponding amount of insulin to balance the glucose generated by the stress response. This compensatory mechanism in diabetic patients is impaired through a relative insulin deficiency (type 2) or absolute insulin deficiency (type 1) necessitating supplementation of insulin in the perioperative period. Anesthetic agents can affect glucose metabolism through the modulation of sympathetic tone; in vitro evidence suggests that inhalational agents suppress insulin secretion. The resulting relative insulin deficiency often leads to glucose dysregulation and hyperglycemia. This deficiency is compounded in diabetics, particularly those with insulin resistance, raising the risks of ketoacidosis. The use of regional anesthesia or peripheral nerve blocks may mitigate these concerns, but no data suggest that these forms of anesthesia will improve postoperative survival in patients with DM. GOALS OF PERIOPERATIVE GLYCEMIC CONTROLSection 7 of 12
The goals for glycemic control are tailored to each patient based on a number of factors, such as nature of surgery, severity of underlying illness, modality used to achieve glycemic control, patient age, and sensitivity to insulin. Numerous clinical trials have involved various patient populations and examined the implications of perioperative hyperglycemia. Based on data derived from these studies, the American Diabetes Association has made recommendations for managing blood glucose levels in hospitalized patients with DM (see Table 1). Table 1. American Diabetes Association Recommendations for Target Inpatient Blood Glucose Concentrations
Prior to elective surgery, it is ideal for patients to have their HbA1c value at less than 6%. More stringent goals may further reduce complications; however, this is at the cost of increased risk of hypoglycemia. Less intensive glycemic control may be indicated in patients with severe or frequent episodes of hypoglycemia. Special populations, such as pregnant and elderly patients with DM, may require additional considerations. In addition, a plan for hypoglycemia should be delineated for individual patients. Methods of Achieving Glycemic Control Because of the numerous potential perioperative complications of hyperglycemia, close monitoring is imperative to maintain tight glycemic control throughout the perioperative period. Certain patients taking oral agents prior to surgery may be able to restart their previous regimen postoperatively; however, appropriateness of oral agents needs to be reassessed because of potential complications (see Table 2). Intravenous insulin is the most flexible and readily titratable agent, with few, if any, contraindications, making it an ideal agent for perioperative use. Table 2. Considerations for Oral Agents
The length, type of surgery, and degree of glycemic dysregulation will dictate the degree of supplemental intravenous insulin therapy. Patients with type 1 diabetes should have elective surgeries scheduled as the first case of the day to minimally disrupt their DM regimen. Depending on the length and extent of surgery, patients are often advised to administer half of their daily dose of long-acting insulin and to arrive at the preoperative admitting area early enough to have an intravenous infusion of dextrose instituted and their serum glucose monitored until the time of surgery. Perioperative methods for achieving tight glycemic control (80-110 mg/dL) are as follows:
An example of such a system is the Glucommander®, presented at the 2003 Diabetes Technology meeting in San Francisco, CA; it is a novel method of attaining optimal glucose control by programming an intravenous infusion of insulin to respond to the measured serum glucose concentration. Initial parameters and baseline glucose value are entered. The program then recommends an insulin infusion rate and intervals to check subsequent glucose levels; this process may be repeated indefinitely. The amount of insulin recommended is based on a simple equation: insulin per hour = multiplier x (blood glucose – 60). Blood glucose concentrations are monitored as frequently as every 20 minutes up to a maximum interval specified in the initial orders. Typically, the monitoring interval is every hour, increasing when glucoses stabilize in the target range and decreasing if sugars are low or falling rapidly. The Glucommander® has been the successfully implemented in the critically ill as well as noncritically ill patient populations. However, intraoperative use has yet to be recommended. Regardless of the methodology implemented, postoperative diabetic patients present logistical challenges different from nonsurgical diabetic patients. Scheduled nutrition is often difficult and frequently interrupted for diagnostic studies or procedures. The regimen selected should accommodate these dynamic changes and reflect the patient's current status, including nutrition state (eg, continuous, intermittent), severity of illness, and catecholamine and/or corticosteroid use, to reduce the likelihood of adverse events. DIABETIC COMPLICATIONS AND PERIOPERATIVE MANAGEMENT CONSIDERATIONSSection 8 of 12
Table 3 summarizes the numerous complications of DM and the methods and modalities designed to minimize perioperative morbidity and mortality. Table 3. Adult Diabetic Complications and Therapeutic Considerations/Strategies
ACE: Angiotensin II converting enzyme ARB: Angiotensin receptor blocker NSAIDs: Nonsteroidal anti-inflammatory drugs * If no contraindication with agent shown to be effective in lowering cardiovascular events ** Other disease states (critical illness) may necessitate higher amounts of protein Perioperative beta-blockade therapy should be considered for all diabetic patients undergoing intermediate or major risk noncardiac surgery as a means to decrease the incidence of postoperative myocardial ischemia and infarction. It is prudent to also assess all patients for orthostatic hypotension. This is easily diagnosed by performing a "tilt test" in the operating room, with patients receiving appropriate intravascular volume resuscitation prior to initiating any form of regional or general anesthesia. Patients suspected of gastroparesis should receive a prokinetic drug prior to general anesthesia to decrease the incidence of gastric acid aspiration. Aseptic technique is critical for all procedures in patients with DM to decrease the incidence of postoperative infection. In this regard, temperature control is also essential in patients with DM, as hypothermia can lead to peripheral insulin resistance, hyperglycemia, deceased wound healing, and infection. Hypothermia per se has been associated with an increase in wound infection following colon resection, craniotomy for cerebral aneurysm clipping, and open heart surgery with cardiopulmonary bypass. Intraoperative management of intravascular volume may require the use of a central venous pressure catheter, a pulmonary artery catheter, or transesophageal echocardiography to best guide therapy and to protect against end-organ hypoperfusion. Arterial blood gas analysis should not only include assessment of blood glucose levels but also levels of sodium, potassium, and assessment of pH. Type 1 diabetic patients are predisposed to developing ketoacidosis during periods of major stress; therefore, they should be monitored by arterial blood gas analysis during and after major surgery. SUMMARYSection 9 of 12
The increasing prevalence of diabetic patients undergoing surgery and the increased risk of complications associated with DM require optimal perioperative assessment and management. Diabetes management and its associated morbidities present a number of challenges; this is becoming an increasingly common medical issue. Data from numerous studies have demonstrated that diabetic patients are at increased risk of significant morbidity and mortality. Correspondingly, the benefits of tight glycemic control have been well documented and, in light of the known complications, have become standard of care. However, despite these data, there is a paucity of literature to guide optimal management. Intensive glycemic control necessitates close monitoring to reduce the incidence of severe hypoglycemia. New methods, such as the Glucommander®, appear to provide an alternative to currently employed methods. However, future research will need to be directed toward elucidating optimal perioperative management of DM. ACKNOWLEDGMENTSSection 10 of 12
The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthor, Raymond Cheung, MD, to the development and writing of this article. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Perioperative Management of the Diabetic Patient excerpt Article Last Updated: May 17, 2006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
