perioperative management of diabetes
Diabetic patients frequently require some type of surgery or an invasive diagnostic procedure, which can even be performed urgently. Currently, the surgical risk of diabetics has decreased thanks to advances in anesthetic techniques and perioperative metabolic control, although complications are even more frequent, leading to prolonged hospitalization and a higher rate of disability. In the preoperative evaluation, the characteristics of diabetes, the type of surgical procedure, the surgical anesthetic risk, and the necessary adjustments to the usual treatment should be specified. Continuous intravenous insulin infusion with glucose supply is the most rational and physiological method in most surgical procedures, which implies frequent glycemic monitoring with immediate adjustments. Some special situations, such as complex or emergency surgeries, require specific therapeutic schemes, so each team must have its own work protocol, depending on the particularities of the surgical interventions they perform. Perioperative metabolic control is essential to avoid acute metabolic and electrolyte alterations and promote satisfactory postoperative evolution. Due to its importance, a review is carried out with a current approach, which helps to improve the quality of care for diabetic patients who require surgical intervention.
Perioperative glycemic control
For a long time it has been debated what the metabolic control of the diabetic patient should be in the perioperative period. The relationship between blood glucose and the appearance of complications in the trans and postoperative period is well known. There is evidence that supports hyperglycemia as a sensitive predictor of nosocomial infections.8-10 An increased risk of infection has been demonstrated with blood glucose levels greater than 11.1 mmol / L, due to phagocytic dysfunction of neutrophils and monocytes.10 Elevated values HbA1c levels in patients undergoing cardiac surgery are more frequently associated with complications such as acute myocardial infarction in the perioperative period.11,12 Based on the above, the goals of good metabolic control prior to elective surgery should be achieved, which may require adjustments in routine treatment (Table 1) .13
In the intraoperative period, the objective of achieving blood glucose levels in a very strict way increases the risk of hypoglycemia in a patient under the effects of anesthesia. The initial studies that evaluated intensive insulin therapy observed a decrease in morbidity and mortality, however, the new evidence does not show benefits with these goals, on the contrary, an increase in the incidence of stroke and death has been reported.14-17 The goal is to maintain reasonable intraoperative blood glucose levels between 7.0 and 11.1 mmol / L, which avoid acute metabolic and electrolyte alterations, which requires adequate blood glucose monitoring throughout the procedure.
The preoperative evaluation should specify the characteristics of diabetes, the type of surgical procedure, determine the surgical anesthetic risk, and make the necessary adjustments to the usual treatment. With regard to diabetes, it is necessary to specify the type of diabetes, the years of evolution, the current treatment, as well as glycemic control, complications and associated comorbidities. The initial assessment by your diabetologist, on an outpatient basis, implies necessary adjustments to the usual treatment, which reduces the hospital stay and improves the final prognosis.
The type of DM and its treatment guide us on the functional pancreatic reserve and insulin needs in the perioperative period, thus, for example, type 2 diabetics tend to have lower insulin secretion and higher IR related to surgical stress. Type 1 diabetics always require continuous insulin therapy. The lack of insulin supply for a few hours, such as due to its bolus administration, due to its short half-life, can activate ketogenesis, with the metabolic disorders that this generates.18,19
It is important to define the presence of chronic complications and their severity. Chronic kidney disease can make it difficult to manage fluids, electrolytes, and affect the pharmacokinetics of insulin. Furthermore, it implies a careful selection of drugs that require dose adjustment due to their renal elimination, or of those that have a nephrotoxic effect. Hyperkalemia is common in advanced stages, while hypokalemia can accompany polyuria and be aggravated by insulin treatment without potassium replacement.20,21
Cardiovascular autonomic neuropathy should be investigated according to available resources, due to the high risk of complications during anesthetic induction. The identification of orthostatic hypotension in the physical examination, as well as the variability of the heart rate, and the Ewing tests, among others, help in the identification of affected patients. On the other hand, genitourinary neuropathy (neurogenic bladder) increases the risk of urinary retention in the postoperative period, and diabetic gastroparesis can delay the initiation of oral feeding. The medical history should specify whether there is a history of hypoglycemia without warning, since these patients are at greater risk of severe episodes.22
The complementary ones should include HbA1c, which provides guidance on metabolic control in the previous weeks, and failing that, the glycemic profile that includes preprandial and postprandial determinations. The electrocardiogram should be performed regardless of whether or not you suffer from previously diagnosed cardiovascular disease, due to the risk of silent ischemia and other signs that support autonomic neuropathy. The determination of potassium through the ionogram allows the adequate treatment of electrolytes in the intraoperative period.19,22
Parameters to assess kidney function include albuminuria, creatinine, and glomerular filtration. Estimation of the latter through established equations is acceptable in clinical practice. For this, the Cockcroft-Gault formula, that of the Modification of Diet in Renal Disease (MDRD) study, available in computerized programs, among others, can be used.23
Surgical risk factors for people with DM: 19-22
- Years of evolution of DM.
- Metabolic uncontrol.
- Cardiovascular, digestive and genitourinary autonomic neuropathy.
- Chronic kidney disease
- Arterial hypertension, ischemic heart disease, cardiomyopathy.
- Presence of infections.
- Altered lung function
Another aspect to consider are the characteristics of the surgery, which also determine the intraoperative treatment and the anesthetic technique:
- Elective or emergency.
- Minor (including invasive diagnostic procedures), or greater (complex or not), by requiring prolonged surgical periods and stay in the intensive care unit (ICU) in the postoperative period, such as heart surgery, revascularizations, transplants, among others.
perioperative management of diabetes : Diabetics requiring major surgery and those with glycemic uncontrol should be admitted at least 12-24 h prior to surgery to stabilize them from a metabolic point of view. All of them require intensive preoperative control, which includes insulin therapy. The multiple-dose insulin regimen achieves this goal, and involves the administration of basal and preprandial bolus insulin with Neutral Protamine Hagedorn (NPH insulin) and regular, respectively, subcutaneously. In patients who already used insulin, their basal dose is maintained, and in both, the necessary adjustments are made with additional supplements. Sliding insulin regimens were deprecated, as they did not show advantages and were less effective.24-27
Glycemic monitoring includes blood glucose determinations before surgery (the night before and the day of surgery), during, and after surgery. If hyperglycemia is identified the night before, it is convenient to rule out a state of associated ketosis, through the Imbert reaction, or test strips for ketonuria.
Surgical interventions should be performed, if possible, in the early hours of the morning, fasting from the night before. When this cannot be possible, the necessary measures should be taken by the surgical team to avoid complications due to prolonged surgical stress, and those related to the treatment regimen used (extended fasting period, administration of hypotonic solutions and dilutional hyponatremia , among other).
Treatment during minor surgery or before an invasive diagnostic technique
Patients controlled with exclusive dietary treatment or with oral glycemic regulating drugs: these patients have a limited endogenous insulin reserve, however, those with good metabolic control do not require special intervention, and insulin treatment is not usually necessary during these Proceedings.20,21,25-28
Sulfonylureas and glinides stimulate insulin secretion, and for this reason, they are usually maintained until the day before surgery and are removed the day of the intervention. Long-acting drugs, such as chlorpropramide, should be suspended 72 hours before proceeding. The biguanides are removed 48 h before; if an intravenous contrast medium is used, do not reintroduce it until after 48-72 hours.
Glucagon-like peptide-1 (GLP-1) receptor agonist drugs, alpha-glucosidase inhibitors, and dipeptidyl-peptidase 4 (DPP-4) inhibitor drugs, they improve postprandial hyperglycemia, so they are not effective during periods of fasting, and are suspended on the day of the intervention. The glitazone group improves glucose utilization in peripheral tissues, but causes fluid retention, so their current use is controversial and they have very limited indications; they should be interrupted days prior to surgery.
If hyperglycemia appears during the procedure, adjustments should be made with regular insulin. If it were necessary to prolong this intervention, one should go, as an alternative, to a scheme with intravenous glucose and insulin intake. The usual treatment is resumed when the oral route is restarted.
Patients with concurrent infection or metabolic lack of control should be insulinized prior to the intervention, and require perioperative treatment similar to that of patients with prior insulin therapy.
Patients with previous insulin treatment: this group of patients should achieve their optimal metabolic control with the adjustment of the insulin dose, or alternatively when it is not possible to change to a more effective regimen, such as multiple doses of insulin, and they should always receive glucose and insulin intraoperatively.25-31
The new evidence does not justify the substitution of long-acting analogs for intermediate-acting ones (PHN) prior to the intervention, on the contrary, the absence of action peaks of the former reduces the risk of hypoglycemia. It is advisable to administer 2/3 of the usual dose of NPH insulin the night before, if you use long-acting analogues, the usual dose can be administered, and patients with an infusion pump will be able to maintain a similar infusion rate.32-34
On the day of the intervention, the morning insulin dose is not injected and a glucose-potassium-insulin infusion regimen (GKI) is established, performing capillary glycemic monitoring every 1-2 h, with adjustments if necessary. Subcutaneous administration of NPH insulin on the day of surgery has less predictable absorption and increases the risk of hypoglycemia. Simple and short-term surgical procedures may be an exception to this recommendation.
Treatment during major surgery
Major surgery involves greater surgical stress than minor intervention, so diabetics who undergo this procedure require a constant supply of glucose and insulin, with closer glycemic monitoring. Another situation to consider are complex surgeries, due to their long surgical time or because they require extracorporeal circulation, inotropic drugs, induced hypothermia, among other situations. In these conditions, insulin needs increase, and the treatment of fluids and electrolytes becomes more complex.
There are different modalities for the intraoperative treatment of fluids and insulin; the selection will depend on the characteristics of the patient and the procedure in question, as well as the particular characteristics of the surgical unit where it is performed. The supply of insulin must be continuous and intravenously during major surgery. Non-insulin-non-dextrose regimens (prolonged fasting period) were discontinued due to the high mortality associated with this, as well as those that include the subcutaneous use of insulin, because its absorption and bolus use are unpredictable. endovenous, taking into account its short half-life. A brief period of insulin deficiency generates peaks and valleys in circulating insulinemia, with deterioration of glycemic control, which can be serious, especially in type 1 diabetics. Therefore, continuous intravenous insulin infusion is the most rational method and Physiological in perioperative treatment in diabetics requiring major surgery, emergency surgery, as well as in patients with unstable DM
Fluid, electrolyte and insulin intake
Glucose: adequate glucose intake (approximately 120 g per day [5 g / h]) prevents protein catabolism in non-diabetic adults. With preoperative fasting and surgical stress, caloric requirements in most diabetics are 510 g of glucose per hour.21,26-29,33 The concentration of the dextrose solution can vary depending on the fluid volume needs to manage. The more concentrated ones are used in cases with volume overload, unlike the less concentrated ones, reserved for when it is necessary to add more volume, with the precaution that their administration for prolonged periods can produce dilutional hyponatremia. 10% dextrose is the most widely used in most surgical protocols.21,27-29,33
Insulin, estimation of needs: there is no exact method to predict intraoperative insulin needs, it is individual for each patient. It is based on the type of diabetes, previous therapy, the degree of glycemic control in relation to the total daily amount of insulin administered (total preoperative dose), and the presence of associated situations that may increase insulin needs. Despite this, clinical experience with insulin infusion systems has shown similar needs for the majority of people with DM who receive surgical treatment, except for patients undergoing long and complex interventions, or those with processes associated with IR.
The estimated starting dose is 0.5-1 U / h for type 1 diabetics and 1-2 U / h for type 2. In general, the dose varies from 1-3 U / h, which is equivalent to 0.10-0.30 U of insulin for each gram of glucose provided in most diabetics. In situations related to IR (obesity, liver disease, sepsis, steroid treatment, among others), the requirements vary between 0.40-0.80 U of insulin per g of glucose supplied. In patients undergoing open heart surgery, the needs can reach up to 0.80-1.20 U of insulin per g of glucose supplied due to increased stress.
Hourly monitoring during the intervention prevents hypoglycaemic episodes from occurring, since under stress conditions, drops in blood glucose are blood sugar unlikely to occur at a rate greater than 2.8 mmol / L / h, unless a hypoglycemic is administered. large amount of volume. Ultrafast analogs can be used intravenously, but they do not confer advantages over regular insulin intraoperatively.
Potassium: the administration of insulin and glucose induce the passage of potassium to the intracellular medium, which requires an adequate supply of this electrolyte. Its determination in the preoperative period allows to calculate the needs. In general, potassium is administered at a rate of 10-20 mmol / L in patients with normal renal function, in the rest of the subjects it must be readjusted