HOW TO SCREEN OUTPATIENTS PRIOR TO SURGERY

the anesthesia consultant

Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board-certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
email rjnov@yahoo.com
phone 650-465-5997

Latest posts by the anesthesia consultant (see all)

Screening prior to outpatient surgery is important. Over 70% of elective surgeries in the United States are ambulatory or outpatient surgeries, in which the patient goes home the same day as the procedure. There are increasing numbers of surgical patients who are elderly, obese, have sleep apnea, or who have multiple medical problems. How do we decide which 70% of surgical candidates are appropriate for outpatient surgery, and which are not?

For the past 16 years I’ve been the Medical Director at a busy Ambulatory Surgery Center (ASC) in Palo Alto, California. ASC Medical Directors are perioperative physicians, responsible for the preoperative, intraoperative, and postoperative management of ambulatory surgery patients. Our surgery center is freestanding, distanced one mile from Stanford University Hospital. The hospital-based technologies of laboratory testing, a blood bank, an ICU, arterial blood gas measurement, and full radiology diagnostics are not available on site. It’s important that patient selection for a freestanding surgery center is precise and safe.

The topic of Ambulatory Anesthesia is well reviewed in the textbook Miller’s Anesthesia, 7th Edition, 2009, Chapter 78, Ambulatory (Outpatient) Anesthesia. With the information in this chapter as a foundation, the following 7 points are guidelines I recommend in the preoperative consultation and selection of appropriate outpatient surgery patients:

  1. The most important factor in deciding if a surgical case is appropriate is not how many medical problems the patient has, but rather the magnitude of the surgical procedure. A patient may have morbid obesity, sleep apnea, and a past history of congestive heart failure, but still safely undergo a non-invasive procedure such as cataract surgery. Conversely, if the patient is healthy, but the scheduled surgery is an invasive procedure such as resection of a mass in the liver, that surgery needs to be done in a hospital.
  2. Because of #1, an ASC will schedule noninvasive procedures such as arthroscopies, head and neck procedures, eye surgeries, minor gynecology and general surgery procedures, gastroenterology endoscopies, plastic surgeries, and dental surgeries. What all these scheduled procedures have in common is that the surgeries (a) will not disrupt the postoperative physiology in a major way, and (b) will not cause excessive pain requires inpatient intravenous narcotics.
  3. One must screen patients preoperatively to identify individuals who have serious medical problems. Our facility uses a comprehensive preoperative telephone interview performed by a medical assistant, two days prior to surgery. The interview documents age, height, weight, Body Mass Index, complete review of systems, list of allergies, and prescription drug history. All information is entered in the patient’s medical record at that time.
  4. Each surgeon’s office assists in the preoperative screening. For all patients who have (a) age over 65, (b) obstructive sleep apnea, (c) cardiac disease or arrhythmia history, (d) significant lung disease, (e) shortness of breath or chest pain, (f) renal failure or hepatic failure, (g) insulin dependent diabetes, or (h) significant neurological abnormality, the surgery office is required to obtain medical clearance from the patient’s Primary Care Provider (PCP).    This PCP clearance note concludes with two questions: 1) Does the patient require any further diagnostic testing prior to the scheduled surgery? And 2) Does the patient require any further therapeutic measures prior to the scheduled surgery?
  5. For each patient identified with significant medical problems, the Medical Director must review the chart and the Primary Care Provider note, and confirm that the patient is an appropriate candidate for the outpatient surgery. The Medical Director may telephone the patient for a more detailed history if indicated. On rare occasions, the Medical Director may arrange to meet and examine the patient prior to the surgical date.
  6. Medical judgment is required, as some ASA III patients with significant comorbidities are candidates for trivial outpatient procedures such as gastroenterology endoscopy or removal of a neuroma from a finger, but are inappropriate candidates for a shoulder arthroscopy or any procedure that requires general endotracheal anesthesia.
  7. What about laboratory testing? Per Miller’s Anesthesia, 7th Edition, 2009, Chapter 78, few preoperative lab tests are indicated prior to most ambulatory surgery. We require a recent ECG for patients with a history of hypertension, cardiac disease, or for any patient over 65 years in age. If this ECG is not included with the Primary Care Provider consultation note, we perform the ECG on site in the preoperative area of our ASC, at no charge to the patient. All diabetic patients have a fasting glucose test done prior to surgery. No electrolytes, hematocrit, renal function tests, or hepatic tests are required on any patient unless that patient’s history indicates a specific reason to mandate those tests.

Utilizing this system, cancellations on the day of surgery are infrequent—well below 1% of the scheduled procedures. The expense of and inconvenience of an Anesthesia Preoperative Clinic are eliminated.

What sort of cases are not approved? Here are examples from my practice regarding patients/procedures who are/are not appropriate for surgery at a freestanding ambulatory surgery center:

  1. A 45-year-old patient with moderately severe obstructive sleep apnea (OSA) is scheduled for a UPPP (uvulopalatalpharyngoplasty). DECISION: NOT APPROPRIATE. Reference: American Society of Anesthesiologist Practice Guidelines of the Perioperative Management of Patients with OSA (https://www.asahq.org/coveo.aspx?q=osa). For airway and palate surgery on an OSA patient, the patient is best observed in a medical facility post-surgery. For any surgery this painful in an OSA patient, the patient will require significant narcotics, which place him at risk for apnea and airway obstruction post-surgery.
  2. A morbidly obese male (Body Mass Index = 40) is scheduled for a shoulder arthroscopy and rotator cuff repair. DECISION: NOT APPROPRIATE. Obesity is not an automatic exclusion criterion for outpatient surgery. Whether to cancel the case or not depends on the nature of the surgery. A shoulder repair often requires significant postoperative narcotics. The intersection of morbid obesity and a painful surgery means it’s best to do the case in a hospital. One could argue that this patient could be done with an interscalene block for postoperative analgesia and then discharged home, but I don’t support this decision. If the block is difficult or ineffective, the anesthesiologist has a morbidly obese patient requiring significant doses of narcotics, and who is scheduled to be discharged home. If this surgery had been a knee arthroscopy and medial meniscectomy it could be an appropriate outpatient surgery, because meniscectomy patients have minimal pain postoperatively.
  3. An 18-year-old male with a positive family history of Malignant Hyperthermia is scheduled for a tympanoplasty. DECISION: APPROPRIATE. A trigger-free general total-intravenous anesthetic with propofol and remifenantil can be given just as safely in an ASC as in a hospital.
  4. A 50-year-old 70-kilogram male with a known difficult airway (ankylosing spondylitis) is scheduled for endoscopic sinus surgery. DECISION: APPROPRIATE. In our ASC, for safety reasons, we have advanced airway equipment including a video laryngoscope and a fiberoptic laryngoscope. If a patient needs an awake intubation, we are prepared to do this safely. This case would be scheduled with a second anesthesiologist available to assist the primary anesthesia attending in securing the airway.
  5. An 80-year-old woman with shortness of breath on exertion is scheduled for a bunionectomy. DECISION: NOT APPROPRIATE. Although foot surgery is not a major invasive procedure, any patient with shortness of breath is inappropriate for ASC surgery. The nature of the dyspnea needs to be determined and remedied prior to surgery or anesthesia of any sort.
  6. A 6-year-old female born without an ear is scheduled for a 9-hour ear graft and reconstruction. DECISION: APPROPRIATE. With modern general anesthetic techniques utilizing sevoflurane and propofol, patients awake promptly. Even after long anesthetics, if the surgery is not painful, patients are usually discharged in stable condition within 60-90 minutes.

There are infinite combinations of patient comorbidities and types of surgeries. The decision regarding which scheduled procedures are appropriate and which are not is both an art and a science. The role of an anesthesiologist/Medical Director as the perioperative physician making these decisions is invaluable.

 

The most popular posts for laypeople on The Anesthesia Consultant include:

How Long Will It Take To Wake Up From General Anesthesia?

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Will I Be Nauseated After General Anesthesia?

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The most popular posts for anesthesia professionals on The Anesthesia Consultant  include:

10 Trends for the Future of Anesthesia

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Published in September 2017:  The second edition of THE DOCTOR AND MR. DYLAN, Dr. Novak’s debut novel, a medical-legal mystery which blends the science and practice of anesthesiology with unforgettable characters, a page-turning plot, and the legacy of Nobel Prize winner Bob Dylan.

KIRKUS REVIEW

In this debut thriller, tragedies strike an anesthesiologist as he tries to start a new life with his son.

Dr. Nico Antone, an anesthesiologist at Stanford University, is married to Alexandra, a high-powered real estate agent obsessed with money. Their son, Johnny, an 11th-grader with immense potential, struggles to get the grades he’ll need to attend an Ivy League college. After a screaming match with Alexandra, Nico moves himself and Johnny from Palo Alto, California, to his frozen childhood home of Hibbing, Minnesota. The move should help Johnny improve his grades and thus seem more attractive to universities, but Nico loves the freedom from his wife, too. Hibbing also happens to be the hometown of music icon Bob Dylan. Joining the hospital staff, Nico runs afoul of a grouchy nurse anesthetist calling himself Bobby Dylan, who plays Dylan songs twice a week in a bar called Heaven’s Door. As Nico and Johnny settle in, their lives turn around; they even start dating the gorgeous mother/daughter pair of Lena and Echo Johnson. However, when Johnny accidentally impregnates Echo, the lives of the Hibbing transplants start to implode. In true page-turner fashion, first-time novelist Novak gets started by killing soulless Alexandra, which accelerates the downfall of his underdog protagonist now accused of murder. Dialogue is pitch-perfect, and the insults hurled between Nico and his wife are as hilarious as they are hurtful: “Are you my husband, Nico? Or my dependent?” The author’s medical expertise proves central to the plot, and there are a few grisly moments, as when “dark blood percolated” from a patient’s nostrils “like coffee grounds.” Bob Dylan details add quirkiness to what might otherwise be a chilly revenge tale; we’re told, for instance, that Dylan taught “every singer with a less-than-perfect voice…how to sneer and twist off syllables.” Courtroom scenes toward the end crackle with energy, though one scene involving a snowmobile ties up a certain plot thread too neatly. By the end, Nico has rolled with a great many punches.

Nuanced characterization and crafty details help this debut soar.

Click on the image below to reach the Amazon link to The Doctor and Mr. Dylan:

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Learn more about Rick Novak’s fiction writing at ricknovak.com by clicking on the picture below:  

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THE OBESE PATIENT AND ANESTHESIA

the anesthesia consultant

Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board-certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
email rjnov@yahoo.com
phone 650-465-5997

Latest posts by the anesthesia consultant (see all)

Obese patients make anesthesiologists’ work more arduous.  Obese patients, especially morbidly obese and super obese patients, are at increased risk when they need surgery.

Perhaps you’re overweight and you wish you weren’t.

Your anesthesiologist wishes the same thing.  Let’s look at the reasons why.

Two hundred million Americans, or 65% of the U.S. adult population, are overweight or obese. Obesity as a disease is second only to smoking as a preventable cause of death.

The body mass index (BMI) has become the most widely applied classification tool used to assess individual weight status.  BMI is defined as the patient’s weight, measured in kilograms, divided by the square of the patient’s height, measured in meters.

A normal BMI is between 18.5 and 24.9.  Patients are considered to be overweight with a BMI between 25 and 29.9 obese with a BMI between 30 and 39.9, morbidly obese between 40 and 49.9, and super obese at greater than 50.

Morbid obesity is associated with far more serious health consequences than moderate obesity, and creates additional challenges for health care providers.  Between 2000 and 2010, the prevalence of morbid obesity in the U.S. increased by 70%, whereas the prevalence of super obesity increased even faster.  It’s estimated that in 2010, 15.5 million adult Americans, or 6.6% of the population, had an actual BMI >40, and carried the diagnosis of morbid obesity.

MEDICAL PROBLEMS ASSOCIATED WITH OBESITY

Obesity is an independent risk factor for heart disease, hypertension, stroke, hyperlipidemia, osteoarthritis, diabetes mellitus, cancer, and obstructive sleep apnea (OSA).  A neck circumference > 17 inches in men or > 16 inches cm in women is associated with obstructive sleep apnea. As a result of these concomitant conditions, obesity is also associated with early death.

There is a clustering of metabolic and physical abnormalities referred to as the “metabolic syndrome.” To be diagnosed with metabolic syndrome, you must have at least three of the following: abdominal obesity, elevated fasting blood sugar, hypertension, low HDL levels, or hypertriglyceridemia.  In the United States, nearly 50 million people have metabolic syndrome, for an age-adjusted prevalence of almost 24%. Of people with metabolic syndrome, more than 83% meet the criterion of obesity. Patients with metabolic syndrome have a higher risk for cardiovascular disease and are at increased risk for all-cause mortality.

Obstructive sleep apnea (OSA) is a condition characterized by recurrent episodes of upper airway obstruction occurring during sleep. Obesity is the greatest risk factor for OSA, and about 70% of patients (up to 80% of males and 50% of females) with OSA are obese.  OSA is defined as complete blockage of airflow during breathing lasting 10 seconds or longer, despite maintenance of neuromuscular ventilatory effort, and occurring five or more times per hour of sleep (Apnea Hypopnea Index, or AHI, greater than or equal to five), and accompanied by a decrease of at least 4% in arterial oxygen saturation.  This diagnosis can be made only in patients who undergo a sleep study. Obstructive sleep apnea is classified as mild, moderate, or severe, as follows:

  • Mild OSA =A HI of 5 to 15 events per hour
  • Moderate OSA = AHI of 15 to 30 events per hour
  • Severe OSA = AHI of more than 30 events per hour

Treatment is recommended for patients with moderate or severe disease, and initial treatment is the wearing of a continuous positive airway pressure (CPAP) device during sleep.

ANESTHETIC CHALLENGES

Every anesthesia task can be more difficult to perform in an obese patient.  Excess adipose tissue (fat) on the upper extremities makes it harder to place an IV catheter.  Excess fat surrounding the mouth, throat, and neck can make it more difficult to place an airway tube.  Excess fat can make it more difficult to place a needle in the proper position for a spinal anesthetic, an epidural anesthetic, or a regional block of a specific peripheral nerve.  On thick, cone-shaped upper arms, it can be difficult for a blood pressure cuff to detect the blood pressure accurately.

During surgery, an anesthesiologist’s job is to maintain the patient’s A-B-C’s of Airway, Breathing, and Circulation, in that order.  All three tasks are more difficult in obese patients.

Airway procedures are often much more difficult to perform in obese patients than in patients with normal BMIs.  Every general anesthetic begins with the anesthesiologist injecting intravenous medications that induce sleep.  Next the anesthesiologist controls the breathing by using a mask over the patient’s face, and then he or she places an airway tube through the patient’s mouth into the windpipe.

The airway anatomy of obese patients, with or without OSA, may show a short, thick neck, large tongue, and significantly increased amounts of soft tissue surrounding the uvula, tonsils, tongue, and lateral aspects of their throats.  This can contribute to the development of airway obstruction and also increase the probability that it will be more difficult to keep the airway open during mask ventilation.  This can also contribute to difficulty placing an anesthesia airway tube into the windpipe at the beginning of general anesthesia.

What about breathing difficulties?  The chief reason that obese patients have difficulty with breathing during anesthesia is that they have abnormally low lung volumes for their size.  When lying flat on their back, a patient’s increased abdominal bulk pushes up on their lungs, and prevents the lungs from inflating fully.  Once the patient is anesthetized, this mechanical situation is worsened, because breathing is impaired by the anesthetic drugs and muscle relaxation allows the abdomen to sink further into the chest.  The essence of the problem is that the abdomen squashes the lungs and makes them less efficient both as a reservoir and as an exchange organ for oxygen.  Because of this, the obese patient is at risk for running out of oxygen and turning blue more quickly than a lean patient.

In one study,  patients undergoing general anesthesia received 100% oxygen by facemask before induction of general anesthesia. After the induction of general anesthesia, the patients were left without ventilation until their oxygen saturation fell from 100% to 90%.  Patients with normal BMIs took 6 minutes for their oxygen level to fall to 90%. Obese patients reached that end point in less than 3 minutes.

What about circulation?  Maintaining stable circulatory status can be difficult because obese patients have a higher prevalence of cardiovascular disease, including hypertension, arrhythmias, stroke, heart failure, and coronary artery disease. During anesthesia and surgery, unexpected high or low blood pressure events are more common in obese patients than in those with normal BMIs.  Morbidly obese patients have a higher rate of heart attack postoperatively than patients with normal BMIs.

Regional anesthesia, especially epidural and spinal anesthesia, is often a safer technique than general anesthesia in obese patients. However, regional anesthesia can be  technically more difficult because of the physical challenge of the anatomy being obscured by excess fat.

Operative times are often longer in obese patients, owing to technical challenges for the surgeon regarding anatomy distorted or hidden behind excessive fat.  Longer surgery means a longer time under general anesthesia, which is a cause of delayed awakening from anesthesia. At the conclusion of surgery, obese patients wake more slowly than lean patients. Anesthetic drug and gas concentrations drop more slowly post-surgery, because traces of the chemicals linger in the reservoirs of excessive adipose tissue.

Common serious postoperative complications in obese patients include blood clots in the legs (deep venous thrombosis) and wound infections at the surgical incision line.

(Reference for this section:  Miller’s Anesthesia, 7th Edition, 2009, Chapter 64).

DATA ON THE RISKS OF OBESITY AND SURGERY

In one landmark study, researchers analyzed postoperative complications in 6,773 patients treated between 2001 and 2005 at the University of Michigan. Of the patients who had complications, 33% were obese and 15% were morbidly obese. Obese patients had much higher rates of postoperative complications than nonobese patients, as follows:  5 times more heart attacks, 4 times more peripheral nerve injuries, 1.7 times more  wound infections, and 1.5 times more urinary tract infections. The overall death rate was no different for obese and nonobese patients, but the death rate was nearly twice as high among morbidly obese patients as compared with nonobese patients (2.2% vs. 1.2%).

CONCLUSIONS

Experienced anesthesiologists respect the risks and difficulties presented by obese, morbidly obese, and super obese patients.  The ranks of overweight Americans are growing, and every week we anesthetize thousands of them for surgery.  As an obese American, are you safe in the operating room?  You probably are, because anesthesia professionals are well-educated in the risks of taking care of you. But you must realize that you are at higher risk for a complication than those with a normal BMI.

What can you do about all this? If you are morbidly obese and your surgery is optional, you may consider not having surgery at all.  If you have time before surgery, you can try to lose weight.  Before any surgery, you should consult your primary care physician to make sure that any obesity-related medical problems have been addressed.  You may be placed on medication for hypertension, hyperlipidemia, or diabetes.  You may have undiagnosed OSA, and may benefit from a nightly CPAP treatment for that disorder.

Bariatric surgery (e.g., gastric banding, gastric bypass) is a well-accepted and effective treatment for weight loss in super obese and morbidly obese patients.  Bariatric surgery refers to surgical alteration of the small intestine or stomach with the aim of producing weight loss. More than 175,000 bariatric surgeries were performed in 2006, and more than 200,000 were performed in 2008 (Miller’s Anesthesia, 7th Edition, 2009, Chapter 64). Weight loss after bariatric surgery is often dramatic. On the average, patients lose 60% of their extra weight. For example, a 350-pound person who is 200 pounds overweight could lose about 120 pounds.  All the anesthetic considerations and risks discussed above would still apply to any patient coming to the operating room for weight loss surgery.

Obesity was considered a rarity until the middle of the 20th century.  Now more than 300,000 deaths per year in the United States and more than $100 billion in annual health care spending are attributable to obesity. Obesity most frequently develops when food calorie intake exceeds energy expenditure over a long period of time.

If you’re obese, this doctor recommends you eat less, and exercise more.  Stay lean if you can.  Your anesthesiologist will thank you.

 

The most popular posts for laypeople on The Anesthesia Consultant include:

How Long Will It Take To Wake Up From General Anesthesia?

Why Did Take Me So Long To Wake From General Anesthesia?

Will I Have a Breathing Tube During Anesthesia?

What Are the Common Anesthesia Medications?

How Safe is Anesthesia in the 21st Century?

Will I Be Nauseated After General Anesthesia?

What Are the Anesthesia Risks For Children?

 

The most popular posts for anesthesia professionals on The Anesthesia Consultant  include:

10 Trends for the Future of Anesthesia

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12 Important Things to Know as You Near the End of Your Anesthesia Training

Should You Cancel Surgery For a Blood Pressure = 178/108?

Advice For Passing the Anesthesia Oral Board Exams

What Personal Characteristics are Necessary to Become a Successful Anesthesiologist?

 

Learn more about Rick Novak’s fiction writing at ricknovak.com by clicking on the picture below:  

DSC04882_edited