a. Age. Advanced age alters dose requirements and elimination of many medications. For sedatives and analgesics, the elderly patient usually requires smaller increments and less frequent dosing intervals compared with younger adults. A reduction of 30% to 50% is a practical approach to initial dosing administration. Metabolism and drug elimination are both slowed in the elderly, which can result in excessive postprocedure sedation and delayed recovery (3). Elderly patients often require more extensive preparation for procedures, and they are at an increased risk for periprocedural complications because of significant concomitant medical disease and age-related impairment of cardiovascular, hepatic, and renal function (4).

b. Cardiovascular disease. Coronary artery disease (CAD), congestive heart failure (CHF), cerebrovascular disease, insulin-dependent diabetes, and serum creatinine >2.0 are important factors associated with increased risk of perioperative cardiac complications. In addition, self-reported exercise ability remains an effective screening tool and has been found to be independently linked with the risk for adverse cardiovascular events (5). Well-controlled hypertension does not present an increased risk (6).

c. Pulmonary disease. Smoking is an important cause of perioperative respiratory morbidity and mortality. Before a procedure, cessation of smoking should be encouraged. Other important patient-related risk factors include poor exercise capacity, chronic obstructive pulmonary disease, acute exacerbations of asthma, and morbid obesity (7).

d. Obesity. Recognition of associated comorbid issues is essential as the prevalence of obesity continues to rise. Obese individuals are at an increased risk for CAD, obstructive sleep apnea (OSA), hypertension, diabetes, and gastroesophageal reflux. In general, the risk will rise with increasing weight, often in a nonlinear fashion. Assessment of exercise tolerance may be difficult to assess secondary to body habitus. Limited pulmonary reserve and OSA contribute to the substantial risk of hypoventilation and obstruction caused by oversedation. Recently published practice guidelines by the American Society of Anesthesiologists may assist in determining the severity and appropriate perioperative management of patients with OSA (8). Additionally, there are pharmacokinetic alterations in the obese patient. In general, the loading dose is based on the volume of distribution and maintenance dose on clearance; however, in the obese population, published dosing information may not be appropriate (9). It has been suggested that dosing of medications, opioids in particular, should be based on lean body mass rather than actual weight (9,10). Morbidly obese patients who require deep sedation should be monitored by an experienced anesthesia provider.

e. Hepatic disease. Reduced hepatic mass is associated with a decreased production of coagulation and drug-binding proteins (e.g., albumin). Initial doses of sedative and analgesic medications should be reduced because altered drug-protein binding can allow excessive “free” (i.e., unbound) drug to enter the central nervous system (CNS). In addition, drug metabolism can be markedly slowed, resulting in prolonged postprocedural sedation (3).

f. Renal disease. Impairment of renal function will slow the ultimate elimination of many drugs, and although initial and maintenance doses may not require reduction, dosing intervals may need to be lengthened. The glomerular filtration rate (GFR) is the best laboratory metric available to determine overall measure of kidney function (11). In patients with renal dysfunction, specific care should be exercised with administration of meperidine (Demerol), since normeperidine, a primary metabolite, can accumulate and lead to CNS stimulation, excitement, and seizures (12).

g. Medication history. Assessment of drug usage patterns and adverse reactions to medications are essential to the provision of safe patient care. Often, a drug effect or side effect (e.g., nausea) is described as an allergy. True allergic reactions to amide local anesthetics (lidocaine and bupivacaine) or benzodiazepines (diazepam and midazolam) are rare.

(1) Maintenance cardiovascular medication should be continued before the procedure. Attention should be given to the beneficial effects of continuing chronic perioperative β-blocker therapy, although starting this therapy immediately preoperatively is of uncertain benefit and may increase risk of complications (6). These can be given with sips of water while maintaining the patient in an otherwise fasted state.

(2) The insulin-dependent diabetic patient requires special consideration. Elective studies in these patients should be scheduled for early in the day. Often, half the usual morning dose of insulin is given and an infusion of 5% dextrose is begun on the day of the procedure. For lengthy procedures, frequent blood sugar determinations should be performed and an insulin infusion considered.

(3) In the elderly patient, adverse drug events from prescribed medications are common but often preventable. Meticulous care must be taken to review the current medication list so that appropriate monitoring of the patient for adverse events can be performed. Specifically, cardiovascular, diuretic, nonopioid analgesic, oral hypoglycemic, and anticoagulant drugs are common medication categories associated with preventable adverse events (13).

a. Overview. Preprocedural laboratory screening is expensive and often contributes little to patient care. When tests are ordered by protocol without
specific indications, few significant abnormalities are found, and many of these determinations could be eliminated without measurably decreasing patient safety (14).

(1) Risk assessment for pregnancy (e.g., urine or serum beta human chorionic gonadotropin hormone [β hCG])

(2) Risk assessment for cardiovascular morbidity (e.g., electrocardiogram [ECG])

(3) Risk assessment for hemorrhagic complications

(4) Evaluation of hepatic and renal function

(5) Guide for preprocedural medical therapy (e.g., transfusion, electrolyte repletion, additional medical consultation)