الفهرس 
Glucose metabolismOnly 14 pages are availabe for public view
 |  | from | 104 |  |  |
| | | from | 104 | | |
Abstract
Hyperglycaemia is a common problem in the perioperative period, linked to the preoperative metabolic state of the patient, neuroendocrine stress response, and acute perioperative insulin resistance, as well as the intraoperative management.
Acute hyperglycaemia may also have its own deleterious effects that can lead to poor perioperative outcomes. It can suppress various aspects of immune function (chemotaxis, phagocytosis, generation of reactive oxygen species, and intracellular killing of bacteria) and increase the circulating inflammatory cytokine concentration. Some of the effects of hyperglycaemia are reported at glucose concentrations > 200 mg/dL.
Patients undergoing elective surgery often suffer from preoperative anxiety, a state of psychological stress involving low-level activation of the hypothalamic-pituitary axis and possibly cytokines.
Preoperative medication is given to temper anxiety, thus attenuating the stress response. Many studies show lower epinephrine and norepinephrine concentrations when propofol (2.0-2.2 mg/kg), rather than thiopental sodium, is used for intubation. This finding is attributed to propofol’s intrinsic ability to inhibit catecholamine secretion, possibly by decreasing catecholamine release from chromaffin cells. Propofol (1.5-2.5 mg/kg) also decreases cortisol concentrations during intubation. Etomidate does not affect metabolic responses except to decrease hyperglycemia. This is attributed to etomidate suppressing the adrenocortical response by blocking cortisol and aldosterone synthesis.
Neuraxial anesthesia is more effective than general anesthesia in attenuating the stress response. The ability of such anesthesia to modify the intraoperative stress response depends on the level of the blockade, the location of the surgery, and the drugs used.
Attenuating the stress response with continuous postoperative epidural analgesia was more successful in lower than upper abdominal surgery, a finding similar to the observations during intraoperative epidural anesthesia.
A significant proportion of patients presenting for perioperative evaluation are likely to have unrecognized impaired glycemic control and are also more likely to develop intraoperative and postoperative hyperglycemia. Perioperative physicians recognize the multisystem impact of diabetes (chronic hyperglycemia) and its relationship to poor perioperative outcomes.
The ADA recommends that the following individuals be screened for diabetes: patients who are older than 45 years; patients who have a body mass index 25 kg/m2 and have the following additional risk factors: first-degree relatives with diabetes, women with gestational diabetes or history of delivering a baby ≥4.1 kg, hypertension, history of cardiovascular disease, high-density lipoprotein cholesterol 35 mg/dL or triglycerides ≥250 mg/dL, women with polycystic ovarian syndrome, or physical inactivity.
Treatment recommendations are generally categorized based on the type of diabetes, nature and extent of the surgical procedure, antecede pharmacological therapy and state of metabolic control before surgery.
In general, oral agents should be discontinued one day before surgery. Sulfonylureas increase the risk of hypoglycaemia; in addition, a longstanding controversy exists regarding the vascular effects of sulfonylureas in patients with cardiac and cerebral ischemia.
Patients receiving insulin before admission can be treated with conventional subcutaneous insulin therapy. If the surgery is to be performed in the morning in a patient treated with intermediate-acting (NPH) insulin, one half of the total morning dose of NPH insulin should be administered.
IV infusion of insulin is the standard therapy for the perioperative management of diabetes, especially in IDDM patients and patients with NIDD undergoing major procedures.