Patient Selection

Appropriately choosing patients who are undergoing surgeries at ASCs is the first step in increasing the likelihood of successful perioperative outcomes. Morbidity and mortality for ambulatory surgeries are very low (<0.1%), confirming the safety of same-day surgeries. While many times the decision to perform ambulatory surgery in a patient with significant comorbidities is made empirically by anesthesiologists and surgeons, there is some evidence that specific conditions may influence perioperative outcomes and are increasingly common in patients presenting to ASCs:

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  Age – while perioperative mortality increases with age, particularly for major surgery and emergency procedures, the risk of death is low for elderly patients in the outpatient setting, with a 7-day mortality rate of 25 per 100,000 procedures at ASCs, compared to 50 per 100,000 procedures at outpatient hospitals, in patients older than 65 years. Elderly patients have a higher incidence of intraoperative cardiovascular events, but not of postoperative events. Patients aged 85 years and older have a higher rate of readmission after ambulatory surgery. Transurethral resection of bladder tumor (TURBT), commonly performed in older adults, is associated with high admission rates.

  
  
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  Hypertension (HTN) – commonly present in the elderly and independently associated with an increased rate of intraoperative cardiovascular events. Blood pressure (BP) values measured in clinic should be 160/100 mmHg or below, and appropriate control and treatment of HTN are recommended. For patients noncompliant with therapy or with unknown baseline BP measurements, or who remain hypertensive despite maximum therapy, a measurement of 180/110 mmHg and below is acceptable, understanding that the period to achieve cardiovascular risk reduction is longer than what is needed for HTN control. If surgery is delayed for HTN control, it is advisable to do it in conjunction with the primary care physician and to allow a period of 6–8 weeks for regression of vascular changes.

  
  
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  Obesity – patients with obesity frequently present with coexisting comorbidities, including HTN, congestive heart failure (CHF), and obstructive sleep apnea (OSA). The prevalence of cardiovascular disease increases as the body mass index (BMI) increases. Obese patients have an increased rate of perioperative respiratory events, although high BMI per se does not increase the risk of difficult intubation. Despite this increase in respiratory events, the rate of unanticipated admission is not higher in obese patients. Performing PNBs is also not free of problems, as block failure rate is higher when obesity is present.

  
  
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  Smoking – associated with an increased risk of postoperative respiratory complications and also with impaired wound healing. Cessation of smoking 4 weeks prior to surgery has been shown to improve outcomes.

  
  
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  Asthma – intraoperative events, such as bronchospasm, occur in approximately 2% of asthma patients. For patients who present with symptoms of asthma, the increase in postoperative respiratory complications is almost fivefold; therefore, it is prudent to ensure that asthmatic patients are medically optimized, and with minimal to no respiratory symptoms before undergoing elective procedures.

  
  
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  Chronic obstructive pulmonary disease (COPD) – patients with COPD have an increased risk of perioperative lower airway events. Patients who have COPD and are asymptomatic do not have longer PACU length of stay, suggesting that respiratory events might be minor. Patients experiencing symptoms are the ones at highest risk of pulmonary complications and should be optimized prior to elective surgery.

  
  
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  Obstructive sleep apnea (OSA) – patients with OSA are more likely to be difficult to intubate and have a higher rate of PACU complications such as HTN, arrhythmias, desaturation, airway obstruction, and need for reintubation. The use of opiates may play a role in the incidence of complications; therefore, judicious use of these agents is advised. If the patient receives treatment with continuous positive airway pressure (CPAP), they need to be proficient in their use. Patients identified at risk of OSA during preoperative assessment should be referred for further assessment with polysomnography.

  
  
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  Coronary artery disease (CAD) – the incidence of perioperative myocardial infarction (MI) in the ambulatory setting is low. Patients with intermediate clinical predictors, including mild ischemic heart disease, acute coronary event over 1 month old, compensated CHF, diabetes mellitus, and renal insufficiency, can undergo low-risk surgical procedures without further testing. Intermediate-risk surgery can proceed without further testing in patients who have functional capacity >4 METS.

  
  
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  Transient ischemic attack (TIA)/cerebrovascular accident (CVA) – the risk of adverse outcomes and postoperative morbidity and mortality is higher in patients with a history of stroke. This risk does not return to baseline but stabilizes 9 months after the event.

Preoperative Assessment

With the increasing number of comorbidities with which patients present when scheduled for ambulatory procedures, an effective way to avoid cancellations on the day of surgery, and to identify patients who need optimization, is to perform a preoperative in-person or over-the-phone consultation, if possible. In terms of preoperative testing, routine tests are not recommended and the approach to perioperative testing should rather focus on what tests are needed to assess specific aspects of the patient’s condition (e.g., HbA1c for diabetic patients) plus reviewing of testing that the patient has undergone as part of follow-up of baseline comorbidities (e.g., ECG for patients with a history of CAD). Additional testing may be requested if the results will change anesthetic management or if testing is needed to make decisions about postponing surgery to optimize baseline conditions. Table 27.1 summarizes the most important questions to ask during preoperative phone assessment.

•Medications – patients should continue taking medications as per their usual schedule, especially cardiovascular, bronchodilating, chronic pain, anxiety, and anticonvulsant agents. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and diuretics are frequently held in the morning of surgery to avoid refractory hypotension; this decision must be made on a case-to-case basis, as patients with CHF or uncontrolled HTN, or who will undergo procedures under regional block (e.g., cataract surgery), may benefit from continuing these agents. Management of insulin and hypoglycemic agents is summarized in Table 27.2.

•Premedication – use of premedication must be assessed on a patient-by-patient basis. There are benefits to the use of low-dose anxiolytics when indicated, in terms of sedation, decreased anxiety, optimization of intraoperative hemodynamic stability, and decreased postoperative side effects, without prolonging recovery from anesthesia. Midazolam remains the most common anxiolytic used for premedication in the ambulatory setting and, at doses of 10–20 μg kg⁻¹, can improve the fast-tracking process by decreasing anxiety-related complications, as well as improve patient comfort level and satisfaction. Patients at risk of aspiration benefit from prophylaxis with a nonparticulate antacid such as sodium citrate/citric acid (Bicitra, 30 mL orally before procedure), an H2 receptor antagonist (ranitidine 50 mg intravenously (IV) before procedure), and especially for patients with diabetic gastroparesis, metoclopramide (10 mg IV before surgery).