Perioperative Management of the

Diabetic Patient

Dr.Masthanamma.C

Dr.Raju.P.S.N

Outline

• Definition

• Statistics

• Diagnostic criteria

• Physiology of glucose metabolism

• Complications of diabetes

Outline

• Pre - anaesthetic evaluation

• Problems faced by a diabetic for surgery

• Goals and methods of achieving periop glycemic control

• Anaesthetic technique and the diabetic patient

• Medical / legal pitfalls

DEFINITION

• Diabetes mellitus is defined as a syndrome characterized by sustained hyperglycemia due to insulin deficiency, impaired insulin action or a combination of both.

Recent statistics

• Diabetes currently affects 246 million people worldwide and is expected to affect 380 million by 2025.

• In 2007, the five countries with the largest numbers of people with diabetes are

• India (40.9 million)

• China (39.8 million)

• United States (19.2 million)

• Russia (9.6 million)

• Germany (7.4 million).

Recent statistics

• Each year 3.8 million deaths are attributable to DM. 

• Cardiovascular disease is the major cause of death in diabetes, accounting for some 50% of all diabetes fatalities, and much disability.

• Every 10 seconds a person dies from diabetes-related causes.

Diagnostic criteria for diabetes according to ADA/WHO guidelines

1 mmol = 18 mgs

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• Type 1 DM :– absolute insulin deficiency, – unopposed catabolic action leads to

hyperglycemia and diabetic ketoacidosis.

• Type 2 DM:– peripheral resistance to insulin,– less susceptible to developing ketoacidosis.

• Mortality / morbidity rates in diabetics have been estimated to be up to 5 times greater than in

nondiabetics

Related to the end-organ damage.

COMPLICATIONS OF DIABETES

• DM is an independent predictor of postop myocardial ischemia and infectious complications in patients undergoing surgery.

• The ultimate goal in the management of diabetic patients is to achieve equivalent outcomes as those patients without DM.

• 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 METABOLISM

• Glucose metabolism is largely a function of the liver, the pancreas, and, to a lesser degree, peripheral tissue.

• Role of liver in glucose regulation: • Extracts glucose • Stores it in the form of glycogen • Performs gluconeogenesis • Glycogenolysis.

• Pancreas secretes counterregulatory hormones:

– Insulin from islet beta cells, which lowers blood glucose concentrations.

– 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.

PREOPERATIVE ASSESSMENT

• Suggestive symptoms - polyuria/polydipsia, blurred vision

• Current Rx of diabetes, including medication regimen, diet, and glucose monitoring results

• Frequency, severity, and etiology of acute complications (ketoacidosis / hypoglycemia)

• Prior or current infections (eg, skin, foot, dental, genitourinary)

• Symptoms and treatment of chronic eye; kidney; nerve; genitourinary, bladder, and GI function; heart; peripheral vascular; foot; and cerebrovascular complications

• Nondiabetic medications that may affect blood glucose levels (eg, corticosteroids)

Preanaesthetic evaluation

• Severity and type of the diabetic state

• Anti-diabetic Medications

• Control of blood sugar

• Treatment regimens used

• Associated complications of DM

• Airway assessment

• Comorbid conditions

physical examination

• Orthostatic hypotension - sign of autonomic neuropathy.

Autonomic neuropathy

• Most commonly a distal symmetrical sensory polyneuropathy with a variable degree of autonomic involvement.

• Autonomic dysfunction, which is of particular importance to the anaesthetist, is detectable in up to 40% of type 1 and 17% of type 2 diabetic

patients

Pathogenic mechanisms for ANP

• Local ischaemia,

• Tissue accumulation of sorbitol

• Altered function of neuronal Na+/K+-ATPase activity

• Immunologically mediated damage

• Diabetic gastroparesis is characterized by a delay in gastric emptying without any gastric outlet obstruction.

• The increased amount of gastric contents enhances the risk of acid aspiration during the induction of anaesthesia

Fundoscopic examination

• Gives insight into the patient's risk of developing postop blindness, especially following major prolonged surgery.

stiff joint” syndrome,

• Significant risk during airway management.

• Affects temporomandibular, atlantooccipital, and other cervical spine joints.

• 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;

• Represents cervical spine immobility and the potential for a difficult endotracheal intubation .

• 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.

• 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.

lab evaluation

• Fasting serum glucose concentration

• HbA1c

• Serum electrolytes

• Blood urea nitrogen

• Creatinine.

• Urinalysis - assess for proteinuria and microalbuminuria.

• Studies have shown a correlation between preop

proteinuria and postop death after CABG, with

the mortality rate increasing proportionally with

the concentration of protein in the urine.

• Based on the nature of surgery, ECG assessing R-R interval during respiration may be useful in the evaluation of autonomic neuropathy.

Loss of R-R variability when the HR at maximal inspiration is compared with the HR at maximal expiration implies the presence of autonomic cardiac neuropathy.

GENERAL PREOP MANAGEMENT

• On the day of surgery, patients on oral regimens should be advised to discontinue these medications.

Sulfonylureas, meglitinides have the potential to cause hypoglycemia.

• 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 s/c as a sliding scale or as a continuous infusion,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 NBM.

Problems faced by a diabetic for surgery

• Surgical stress response with catabolic hormone secretion

• NBM, which may be prolonged following GI procedures

• Altered consciousness - masks the symptoms of hypoglycaemia

• Circulatory disturbances - which may alter the absorption of s/c insulin.

METABOLIC RESPONSE TO ANESTHESIA AND SURGERY

• 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.

• 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 CONTROL

• The goals for glycemic control are tailored to each patient based on:

• Nature of surgery, • Severity of underlying illness, • Modality used to achieve glycemic control• Patient age, • Sensitivity to insulin.

• Prior to elective surgery, it is ideal for patients to have their HbA1c < 6%.

• Less intensive glycemic control may be indicated in patients with severe or frequent episodes of hypoglycemia.

Methods of Achieving Glycemic Control

• Intravenous insulin is the most flexible and readily titratable agent, with few, if any, contraindications, making it an ideal agent for perioperative use.

• 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.

• Administer half of their daily dose of long-acting insulin.

• Arrive at the preop admitting area early enough to have an I.v infusion of dextrose instituted and their serum glucose monitored until the time of surgery.

• Establish separate iv access for a “piggyback” infusion of regular insulin .

• The infusion rate can be determined by using the formula: insulin (U/h) = serum glucose (mg/dL)/150.

• Intravenous glucose solution should be administered concomitantly to avoid hypoglycemia.

• Typically, a 5% D solution is started when serum glucose levels are less than 150 mg/dL.

• 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.

• Temperature control is also essential in patients with DM, as hypothermia can lead to peripheral insulin resistance, hyperglycemia, deceased wound healing, and infection.

• Intraop management of intravascular volume may require the use of a central venous pressure catheter, a pulmonary artery catheter, or TEE 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.

General guidelines for periop control of diabetes

• Check blood glucose, urea, electrolytes and urinary ketones

• Adjust insulin therapy BD – soluble isophane insulin

• Poor control: change to TID – soluble insulin and delay elective surgery

• Urgent surgery: glucose insulin infusion

Day of surgery

• Check fasting sugar

• No subcutaneous insulin

• Start 10% D (500ml) with 10 U human insulin and KCI 1Ommol for 4-6 h

• Adjust insulin according to the blood sugar values <4 No insulin4-6 Insulin 5 U / 500 mL 10%glucose6-10 Same as above10-20 15 U/ 500 Ml 10% glucose>20 20 U/500 mL 10%glucose

• K+ is adjusted according to serum K+

K+<3 mmol/L add 20 mmol K+/500 ml

K+>5 mmol/L no KCI

Postop major surgery

• Check blood sugar every 2-6 h

• Check urea, electrolytes every 4-6h

• Continue infusion till oral feeding is established

• If feeding is delayed, change to 20% glucose with less volume

• When oral diet is established, q8h soluble insulin prior to each feed

• When insulin requirements are stable,restart the preoperative regimen

Emergency surgery and DKA

• DKA results from inadequate insulin dosage or increased insulin requirement often precipitated by trauma, infection or surgical stress.

• Administer insulin at the rate of 4-8U/hr, depending on factors such as blood sugar levels, ketosis and acidosis.

• Correct dehydration, sodium depletion and subsequent potassium depletion

• Replace fluids with isotonic solution of NaCI 1 L in 30 min,1 L in the next hour and further 1 L over the next 2 hours.

• Monitor blood glucose levels, arterial pH and blood gases

• K+may be normal or elevated due to presence of acidosis

• Magnesium 5-10 mmol is also required along with K+ depletion.

• 5% D can be started when blood glucose decreasesto 15 mmol/L

• Surgery is ideally carried out after reversal of acidosis and hyperglycemia.

• However, if the indication for surgery is emergent, surgery can be started when volume resuscitation is underway, with the diabetic management being continued in the intraop and postop periods.

Tight control of blood glucose

• Tight control of blood sugar between 80 – 120 mgs/dL

– Prevents ischemia– Improves wound healing– Improves weaning from CPB

REGIMEN - 1

• Preprandial sugar levels on the evening before surgery.

• Start infusion of 5% D at the rate of 50 ml/hr

• To this infusion, piggyback regular insulin 50 U in 250 ml 0.9 Nacl.

• Set the infusion rate U/hr = Plasma glucose 150

REGIMEN - 1

• Repeat glucose values q4h, and adjust insulin infusion to achieve plasma glucose of 100-200 mg/dl.

• Intraop - use non dextrose containing fluids.

• Determine plasma glucose q2h and adjust insulin accordingly.

• Serum K+ should be checked and adjusted accordingly with particular care for poor renal function.

Anaesthetic technique and the diabetic patient

• Regional blockade, may modulate the secretion of the catabolic hormones and any residual insulin secretion.

• The periop increase in circulating glucose, epinephrine and cortisol concentrations found in non-diabetics exposed to surgical stress under GA is blocked by epidural anaesthesia

• The perioperative infusion of phentolamine, a competitive -adrenergic receptor blocking drug, decreases the glycaemic response to surgery by partially reversing the suppression of insulin secretion

• Regional anaesthesia may carry greater risks in the diabetic patient with autonomic neuropathy.

• Profound hypotension may occur with deleterious consequences in a patient with co-existing coronary artery, cerebrovascular or renovascular disease

Medical / Legal Pitfalls

• Overtreatment or undertreatment of hypoglycemia, eg, premature discharge of a patient who develops hypoglycemia due to a sulfonylurea agent, is a pitfall.

• Failure to record the blood glucose levels of patients with wounds or active infections when they are <250 mg/dL is a pitfall and may lead to poor healing.

Medical / Legal Pitfalls

• Failure to provide adequate hydration to patients with mild diabetic nephropathy before contrast material is given may precipitate acute renal failure.

• Failure to examine the patient's feet and failure to detect small ulcers or underestimation of their seriousness are also pitfalls.

• Failure to consider myocardial ischemia in patients with nonspecific symptoms is a pitfall.

Conclusions

• There have been major advances in the last few years in understanding and treating complications of diabetes.

• The main focus has been on good glycemic control.

• The incidence of diabetes is on the rise in most populations, with Indians being more prone to develop diabetes.

• Diabetes mellitus is likely to be the most common comorbid factor encountered in Surgical practice.

• A clear understanding of the metabolic process, well controlled glycemic regimens and excellent periop care will go a long way towards decreasing the mortality and morbidity in diabetes patients.

THANK YOU