SIGNS OF TROUBLE Several factors suggest potential difficult airways, which should be a red flag for any freestanding surgery center.

As more and more complex procedures find their way into outpatient facilities, it's crucial for your anesthesia providers to determine which patients are appropriate for same-day surgery — and which are not. But how do they do it? As you'll see, there's no foolproof way to determine who's a good candidate for outpatient surgery.

Most of us are familiar with the ASA scores, but they really don't measure operative risk (see "ASA Scores Don't Measure Operative Risk"). Keep in mind that all outpatient facilities are not created equal. A patient who may not be a candidate for office-based surgery may be fine in a surgery center. And a patient who may not be a candidate for a freestanding ASC may be fine in a hospital-based outpatient center.

Here are some red flags and considerations when it comes to patient selection:

• Age (But physiologic age is more important than chronological age.)
• Abnormalities of major organ systems
• Expected difficult airways, based on Mallampati score, recessed chin, major overbite, small mouth or large tongue
• Morbid obesity (greater than 40 BMI)
• Obstructive sleep apnea with continuous positive airway pressure (CPAP)
• Previous adverse events with anesthesia, including malignant hyperthermia and pseudocholinesterase deficiency
• Current medications that may adversely affect anesthetic choices or outcomes
• Smoking or a history of alcohol or drug abuse (We shouldn't hesitate to ask patients if they use street drugs, and if so, what and how often.)
• Psychological status (Some patients need general anesthesia, because they get extremely claustrophobic if their faces are covered.)
• Support system (If needed, is someone available to care for them at home?)
• Coagulation (Is there a risk of DVT or pulmonary embolism?)

Carefully review lab tests, with particular focus on known underlying conditions. Women of childbearing age should have HCG levels tested, but most lab studies are not necessary, and the practice of getting an EKG on everyone, regardless of condition, has fallen by the wayside.

ASC concerns
Other risks related to anesthesia at an ASC include:

• Signs and symptoms of coronary artery disease (CAD), including significant dysrhythmias, significant valvular disease or a pacemaker (with or without AICD)
• History of stroke, especially one with residual effects
• Reactive airway disease, including COPD and/or asthma, especially when asthma patients are symptomatic and dependent on inhalers. Asymptomatic asthmatic patients are low risk for complications, but patients with COPD and asthma are at an increased risk of bronchospasm.
• End-stage renal disease (This requires a detailed history and physical assessment, because many of these patients have comorbidities, such as CAD, diabetes or congestive heart failure.)
• High risk of bleeding due to platelet dysfunction
• Obesity (A BMI of 35 or greater, when combined with other comorbidities, is associated with an increase in intraoperative respiratory events, which could result in desaturation or bronchospasm.)

A NEBULOUS SYSTEM
ASA Scores Don't Measure Operative Risk

'ASA SCORES' How well do physical status scores determine a patient's surgical risk?

The term "ASA scores" is a misnomer. Those Roman numerals are physical status scores designed to measure pre-operative health status, not operative risk, which really diminishes the value of the ASA Physical Status Classification System when determining a patient's surgical risk.

For one thing, ASA scores are subjective. What one person sees as a PS III patient, another sees as a PS IV. I've seen it happen. A returning patient, with no physical changes, sees a different provider and gets a different rating. The system also leans heavily on the word "systemic," which can be confusing. As another colleague points out, a heart attack, though grave, is a "local" rather than systemic disease. So myocardial infarction patients, in the absence of any other systemic diseases, don't really fit into any one category. But they have poorer post-surgery survival rates.

Moreover, people often create their own criteria, and some surgical facility websites list incorrect definitions. At any rate, here's a capsule summary of 1 through 5:

PS I. The patient is completely healthy and can tolerate exercise.

PS II. The patient has mild or well-controlled systemic disease of one body system, or is a smoker but shows no evidence of COPD, or is mildly obese, or is older than 70, but has no functional limitations.

PS III. The patient has a severe systemic disease that isn't incapacitating, but that results in some functional limitation, or has a controlled disease of more than one body system or of a major system, with intermittent symptoms or chronic renal failure.

PS IV. The patient has incapacitating disease that's a constant threat to life, or at least 1 severe disease that's poorly controlled or at end stage.

PS V. The patient is moribund and not expected to live 24 hours, with or without surgery.

The problem? With the exceptions of 1 and 5, the system is nebulous, at best. Consider, for example, a 71-year-old man with well-controlled hypertension and well-controlled diabetes. Let's say he walks a mile every day and has no other limitations. Since he's 71, he can't be a PS I. And since he has controlled hypertension and diabetes, he drops all the way down to a III. But is that an accurate assessment? Frankly, no. And it helps illustrate why many anesthesiologists and CRNAs think the system is flawed.

This calls to mind an anesthesia colleague. Whenever a circulator asks, "What's the ASA?" she replies, "The American Society of Anesthesiologists!" And she's right!

— Perry V. Ruspantine, CRNA, APRN

When to postpone surgery
Certain conditions may necessitate canceling or delaying surgery, or moving it to a hospital. These include:

• OSA requiring CPAP, when combined with BMI above 40
• A positive pregnancy test (depending on the type of surgery)
• Poorly controlled diabetes or fasting blood sugar above 200 or below 60 that can't be controlled on site.

And these conditions or situations suggest that no surgery should be performed unless absolutely necessary:

• Cardiac disease, including unstable coronary syndrome, a heart attack within the previous 30 days (many facilities say 6 months), new onset angina, unstable angina resistant to nitroglycerin sublingual, angina at rest, untreated or undiagnosed new-onset atrial fibrillation (AF), AF with a resting heart rate greater than 110, active supraventricular tachycardia, decompensated heart failure, severe valvular heart disease with stenotic lesions, stent insertion less than 6 weeks before, and severe aortic stenosis with syncope, chest pain and dyspnea. Pacemakers are OK, but with AICDs, consult a cardiologist.
• Severe pulmonary hypertension
• Recent stroke. The AHA and a study published in JAMA recommend that these patients wait 6 months before elective surgery.
• Oxygen dependency with multiple comorbidities, or severe shortness of breath at rest.
• Psychological or mental inability to understand the situation or the surgery, such as an Alzheimer's patient.

Cataract surgery, which is exceedingly low risk, is an exception to the rule. The only conditions that would likely dictate cancellation are severe claustrophobia or severe comorbidities.

Greater challenges ahead
It's likely that some of the patients scheduled for surgeries at your facility simply aren't suitable candidates. In an ideal world, we'd spot these folks during pre-operative evaluations, but inevitably, some slip through the cracks. Your anesthesia providers are the last line of defense. As the gatekeepers for patient evaluation, they determine which patients are outpatient appropriate, and which aren't. OSM