diabetic patients suitable candidates for ambulatory surgery?
Diabetic patients may present a major challenge
for the anesthesiologist when scheduled for ambulatory surgery. Because of the
critical nature of glucose homeostasis, it may be advisable to handle
exceptionally brittle diabetics on an inpatient basis. Preoperatively, diabetic
patients must be carefully assessed for the presence of end-organ damage.
Cardiovascular disease, autonomic and renal insufficiency, and gastroparesis
may lead to potential problems in the perioperative period.
It is preferable to schedule surgery on the
insulin-dependent diabetic as the first or second case of the day. The major
concerns, of course, are to avoid the extremes of plasma glucose, both
hypoglycemia and hyperglycemia, as well as acidosis. Delays in insulin
administration may lead to ketoacidosis despite the fasting state. For this
reason, it is recommended that patients receive insulin along with a continuous
infusion of dextrose on arrival at the ambulatory surgery facility. Insulin may
be administered by either the subcutaneous or intravenous route. The relative
advantage, if any, of administering a continuous infusion of regular insulin
versus one third to one half of the usual long-acting insulin dose
subcutaneously has not been demonstrated. Another option for early-morning
surgical procedures is to administer the usual long-acting insulin dose
subcuta-neously immediately following surgery and shift the time of all meals
and future insulin injections by the same offset.
Non-insulin-dependent diabetics who are
controlled by one of the available oral hypoglycemic agents must also be
carefully monitored in the perioperative period by periodic fingerstick or
blood glucose determinations. The half-life of some of the oral agents may be
as long as 60 hours (chlorpropamide). Fortunately, patients with adult-onset,
non-insulin-dependent diabetes mellitus (NIDDM) rarely develop ketoacidosis.
However, this group may develop hyperosmolar, nonketotic coma when significant
hyper-glycemia and dehydration occur.
Before discharge, it is critical that diabetic
patients be capable of eating and be relatively free of significant nausea that
might lead to emesis and inability to maintain adequate caloric intake.