Surgery In Diabetes Mellitus (DM) Walid Sayed Abdelkader Hassanen Specialist of internal Medicine March 2010

Surgery In Diabetes Mellitus Hyperglycemia leads to impaired wound healing , deficient formation of granulation tissue. The chemotactic , phagocytic, and bacterial activity of the neutrophil is deficient , there is impaired hormonal host defense mechanism and abnormal complement function.

Metabolic sequelae in a surgical patient Increased glycogenolysis Increased gluconeogenesis hyperglycemia Decreased glucose utilization: Lipolysis with increased FFA Protein breakdown Increased nitrogen loss Increased urea production Increased sodium retension & potassium execretion and alteration of water metabolism ( increased ADH and increased aldosterone secretion ) free fatty acid (FFA) Antidiuretic hormone (ADH)

Determinents of the management plan Type of DM Treatment, diet, oral antidiabetic drugs, insulin Metabolic status Vascular status: cardiac, renal, cerebral Surgery: Type: emergency or elective Minor or major procedure Type of anesthesia Post operative oral intake

Pre-operative management Metabolic stress of surgery and anesthesia cause increased elaboration of catecholamins, glucocorticoids, glucagon, and growth hormone, all producing their metabolic effects resulting in hyperglycemia in the pre-operative period. The glycemic control is aimed to achieve a fasting plasma glucose of < 140 mg % and post prandial plasma glucose of < 200 mg %. Insulin dependent diabetic patients can be admitted 2-3 days prior to surgery to achieve satisfactory control.

Cont. In NIDDM patients if the control is good with oral antidiabetic drugs , these drugs are stopped on the day of the surgery and intravenous fluids and insulin are given , if not are advised to stop drugs one week before surgery and admitted for insulin therapy. NIDDM - noninsulin-dependent diabetes mellitus

Subcutaneous insulin therapy after admission When the fasting plasma glucose is 140 mg % to give 4 units of soluble insulin subcutaneously before breakfast and then monitor before lunch blood sugar , if the pre- lunch blood sugar is around 140 mg % it is advisable to give the same 4 units soluble insulin pre- meal. For every 40 mg rise in pre- meal blood sugar , pre-meal one unit of soluble insulin is added to the previous dose of pre-meal insulin If the blood sugar level is more than 300 mg % 15 units of soluble insulin pre-meal three times a day is tried.

Practical aspects In a few diabetics it is difficult to control fasting plasma glucose with pre-meal bolus soluble insulin, this situation requires addition of small dose of intermediate acting insulin at bed time. In a few NIDDM patients the blood sugar can not be controlled only with insulin, adding small doses of oral antidiabetic drug is rationale as this overcomes the resistance, on the day of surgery oral drugs are stopped.

On the day of surgery It is preferable to take diabetic patients for surgery in the morning as first case. Normally the requirement of insulin is 0.3 U to metabolize 1gm of glucose. When FPG < 120 mg % no insulin is given except 5% glucose. When FPG 120- 160 mg % 5 % glucose with 5 units soluble insulin. For FPG 160- 200 mg % 5 % glucose with 8 U of soluble insulin. FPG - fasting plasma glucose

Cont. If FPG crosses 200 and < 250 mg % 5 % glucose with 10 U of soluble insulin. Values between 250- 300 mg % to give normal saline with 6-8 U . If the blood sugar > 300 mg % 8-10 U are added to normal saline and surgery is delayed for few hours till satisfactory glycemic control is achieved. All the above infusions are given at the rate of 100-120 ml / h .

Post operative management With the resumption of oral feeds subcutaneous insulin can be started, NIDDM patients can resume their oral antidiabetic drugs after week if there is no complications of surgery.

Intravenous fluids Dextrose saline / normal saline is used if blood pressure is low or normal. If there is hypertension half normal saline or 5 % dextrose is given. For normal metabolism 50 gm glucose is required every 8 hours for energy and to avoid ketosis, to meet this demand at least 1000 cc 5 % glucose every 8 h will be required. In situations requiring fluid restriction 10 % dextrose can be infused instead of 5 % with double the dose of insulin.

Practical aspects Whatever is the pattern of infusion, the blood sugar has to be checked every tow hours and the flow rate is adjusted. Intra and post operative potassium monitoring is done and corrected appropriately. A few hours after surgery there will be reduction in the insulin requirement as the elevated counter hormones due to surgical stress decline.

Emergency surgery In emergency surgery it is deal to use intravenous insulin infusion.

Minor surgery For minor surgery the antidiabetic drugs and insulin are stopped on the day of surgery, once the surgery is over and the patient is permitted to resume oral feeds the antidiabetic drugs are started with half the dose which the patient was originally taking, on the second post operative day full dose of the oral drugs and or insulin are started.

Special situations Blood sugar may rapidly fall after surgical drainage of an infected area. Type 2 diabetes can be safely switched over to oral drugs after a week. In coronary artery bypass surgery and during and after renal transplantation the insulin requirements will be exceptionally high.

Our aim To make patients safe for surgery, for this we need an understanding team work between the surgeon, anesthetist and diabetologist. When the patient is under anesthesia the ideal is to have diabetic therapy supervised by a diabetic team where available.

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