Surgery and diabetes

Perioperative management of type 1 diabetes mellitus

Clearly, perioperative management of diabetic patients requires thorough preoperative evaluation and planning whenever possible. A firm understanding of the pathophysiology of type 1 diabetes mellitus, the metabolic stress response, and the interactions between various forms of insulin and other variables such as supplemental nutrition and glucocorticoids can greatly assist in achieving a positive outcome. Consultation with an endocrinologist, internist, or other primary care provider comfortable with managing type 1 diabetes patients is strongly recommended to assist in the details of in-patient care and overseeing of proper ancillary support. It may also be helpful to allow the patient to function as an active decision-maker in the coordination of care, especially because a large percentage of type 1 diabetes patients (particularly those who are on insulin pumps) are well-educated about their disease process and their own physiologic idiosyncrasies. This knowledge can save valuable time and effort toward achieving the ultimate united goal of avoiding perioperative morbidity and mortality by maximizing glycemic control.

Insulin subcutaneous application vs. continuous infusion for postoperative blood glucose control in patients with non-insulin-dependent diabetes mellitus

BACKGROUND

Frequently, the use of insulin is considered for metabolic control in postoperative patients with non-insulin-dependent diabetes mellitus (NIDDM). We sought to determine the best method for control of glucose in NIDDM non-insulin patients during postoperative care.

METHODS

Two algorithms were developed: subcutaneous administration of insulin (SC), and continuous intravenous infusion (IV). A randomized, controlled clinical trial was designed. In addition, both experimental groups were compared with a non-concurrent routinely managed group (RM) with insulin administration under no predetermined algorithm. Eligible patients were those subjected to major surgery under general anesthesia or spinal blockade. They were followed for 48 h after surgery. Target variables were capillary and central blood glucose, insulin dose administered, urine glucose and ketone strip determination, and development of hyper- or hypoglycemia.

RESULTS

A total of 62 patients were studied (RM = 25, SC = 19, IV = 18). Results for both experimental algorithms were similar except for the IV group that required less insulin per hour compared to SC (0.64 vs. 0.34 U/h; p = 0.0003). The RM control group showed poor control in all capillary glucose measurements (194.9 +/- 26.8 mg/dL) compared with the two experimental algorithms (SC = 129.9 +/- 21; IV = 131.6 +/- 20.4) (p <0.05). More hyperglycemia events appeared in the RM group (p = 0.016). Only one hypoglycemia event occurred in the IV group.

CONCLUSIONS

Postoperative control of NIDDM is similar with both tested methods. The use of any of the algorithms studied improves metabolic control substantially because it standardizes postoperative management of the diabetic patient with timely determination of capillary blood glucose and insulin administration. However, IV administration has the advantage of accomplishing adequate control with a smaller insulin dose.

The control of blood glucose in the critical diabetic patient: a neuro-fuzzy method

Conventional algorithms for regulating insulin infusion rates in those critical diabetic patients submitted to parenteral glucose and insulin infusions do not allow to approach near normal blood glucose (BG) levels since traditional control systems are not fully effective in complex nonlinear systems as BG control is. Thus, we applied fuzzy logic principles and neural network techniques to modify intravenous insulin administration rates during glucose infusion. Forty critically ill, fasted diabetic subjects submitted to glucose and potassium infusion entered the study. They were randomly assigned to two treatment regimes: in group A, insulin infusion rates were adjusted, every 4 h at any step between -1.5 and +1.5 U/h, according to a neuro-fuzzy nomogram; in control group B, insulin infusion rates were modified according to a conventional algorithm. In group A, BG was lowered below 10 mmol/l faster than in group B (8.2+/-0.7 vs. 13+/-1.8 h, P<.02). Mean BG was 7.8+/-0.2 in group A and 10.6+/-0.3 mmol/l in group B (P<.00001). BG values below 4.4 mmol/l were: A=5.8% and B=10.2%. BG values lower than 2.5 mmol/l had never been observed. In conclusion, the neuro-fuzzy control system is effective in improving the BG control in critical diabetic patients without increasing either the number of BG determinations or the risk of hypoglycemia.

Preparing the azotemic diabetic patient for surgery

Azotemic diabetic patients have more risk of complications during or after surgery than those without diabetes and azotemia. These complications include infection, excessive bleeding, cardiovascular events, and electrolyte imbalance. The appropriate preoperative evaluation, measures to be taken to avoid the complications, and how to adequately manage blood sugar during surgery is discussed.

Hospital management of diabetes

The degree of hyperglycemia may be an important predictor of morbidity and mortality among patients with MI or stroke, and in those undergoing surgical procedures including coronary artery bypass. Hyperglycemia should be aggressively controlled from the time of hospital admission regardless of the patient's primary medical problem or previous diabetes status. Innovative systems for monitoring glucose and for delivering insulin coupled with new pharmacologic therapy, such as long-acting insulin analogues, may help reduce the morbidity and mortality occurring in the estimated 6 million annual hospitalizations that are accompanied by hyperglycemia in the United States.

Medical clearance for gynecologic surgery

Physicians are charged to "foremost do no harm." Thus, before doing any surgical procedure, surgeons must convince themselves that the risk to the patient does not outweigh the benefit. The patient with multiple medical problems has additional risk factors for elective surgery. In the past, that patient would be sent to their general practitioner for "medical clearance." With gynecologists now assuming that role for the patient, it is increasingly important for us to understand what comprises medical clearance to better assess hazards. Studies concerning medical clearance for surgery obtained in a MEDLINE search through March 1997 were reviewed; the recent advances that apply to gynecologic surgery are covered in this article.

Perioperative management with prolonged intravenous insulin infusion versus subcutaneous insulin in children with type I diabetes mellitus

Our objective was to retrospectively evaluate glycemic excursion and insulin dosage in the perioperative period in children and adolescents with type I diabetes mellitus receiving prolonged intravenous insulin infusion for 2-3 days compared to conventional subcutaneous insulin treatment. A retrospective review of surgical admissions at the Children's Hospital of Los Angeles in patients with type I diabetes mellitus was conducted for the 3-year period from July 1989 to June 1992, to evaluate two treatment protocols used during that period. For the nine admissions in group 1, patients received 0.06-0.1 units regular insulin/kg/h beginning 2 h prior to surgery and lasting for 2-3 days postoperatively; while, for the ten admissions in group 2 subjects were given subcutaneous regular and intermediate-acting insulin as 2-4 injections daily, with the regular insulin dose prior to surgery decreased to 66-75% of usual. Blood glucose levels were determined at the bedside at hourly intervals and insulin dose adjustment done with the aim of achieving blood glucose levels between 5.5 and 8.3 mmol/L (100-150 mg/dL). The mean bedside blood glucose levels for group 2 were significantly higher 1 h prior to surgery and during the intraoperative period (p < 0.05). In the postoperative period, group 2 blood glucose levels were significantly higher at multiple times for up to 3 days with multiple levels greater than 11.1 mmol/L (200 mg/dL), which was not seen in group 1. The mean insulin dosage (units/kg) prior to admission was not different for the two groups. On the day of surgery and during postoperative days 1 and 2, patients in group 1 received a greater insulin dosage than group 2 subjects (p < 0.025). In group 1, insulin dosage was increased 23% and 15% over baseline for postoperative days 1 and 2, respectively, then, by day 3, was decreased back toward the baseline. In group 2 subjects, a 13.8% increase occurred on the day of surgery due to extra insulin given immediately following the procedures, followed by a 5.4, 44.2, and 66.6% increase over baseline for postoperative days 1 through 3, respectively. In conclusion, meticulous glycemic control was readily achieved in the perioperative period with a constant intravenous insulin infusion for up to 3 days in children and adolescents with type I diabetes. To achieve glycemic control, insulin dosage needs to be increased on the day of surgery and for approximately 2 postoperative days.

Management of diabetes in surgery: a survey of current practice by anaesthetists

A questionnaire survey of anaesthetists, based at the three main hospitals in Bristol, was undertaken to determine what methods are currently being used by anaesthetists to manage diabetes in patients for surgery. Replies were received from 56 of the 90 anaesthetists (62%). Surgical procedures were defined as minor, moderate, and major. Two areas were identified where considerable differences in management between anaesthetists occurred, namely insulin-treated patients requiring minor surgery, and non-insulin-treated patients requiring moderate surgery. In addition, no consensus view was apparent for the preferred intra-operative blood glucose range or for the threshold blood glucose level at which to postpone an operation. It was apparent that anaesthetists preferred to administer intravenous insulin by a syringe pump rather than by a drip bag containing insulin, potassium, and glucose, particularly if more severe metabolic upset was anticipated. No difference in management was apparent between different hospital grades or between the three hospitals.