Advice from anesthesiologists
According to the Centers for Disease Control and Prevention, approximately 12.5 million children and adolescents between ages 2 and 19 are obese. Recently, AAOS Now editorial board member Howard R. Epps, MD, sat down with two anesthesiologists—Nancy L. Glass, MD, professor of anesthesiology and pediatrics at the Baylor College of Medicine in Houston, Texas, and Olubukola O. Nafiu, MD, assistant professor of anesthesiology at the University of Michigan in Ann Arbor—to get their input on perioperative management of these patients.
Dr. Epps: As orthopaedists, we are frequently confronted with an obese child who needs surgical care. What do we need to be thinking about when preparing an obese child for surgery?
Dr. Nafiu: Apart from obviously documenting the most recent body mass index (BMI), the following are important preoperative screening areas: respiratory morbidities like asthma, snoring, or sleep-disordered breathing; gastroesophageal reflux disease (GERD); cardiac disease (hypertension); and diabetes.
Dr. Glass: In evaluating the obese child for outpatient surgery, we as anesthesiologists have several issues. We worry about airway management in these children. Intubating a morbidly obese adult patient using standard tools is very difficult and sometimes impossible. That is not usually the case in obese pediatric patients, probably because the gibbous on the back of the neck has not yet developed.
We are also concerned about the difficultly in placing an intravenous (IV) line, particularly in an emergency situation, when the IV must be placed preoperatively so that we can perform a rapid sequence induction to protect against regurgitation and pulmonary aspiration.
Dr. Epps: If I have an obese patient with Blount’s disease scheduled for elective surgery, would you recommend that the patient drink clear liquids up to 2 hours before surgery to facilitate IV access?
Dr. Glass: Giving clear liquids up to 2 hours before surgery would not be wrong. I am not sure that I could say in a teenager that drinking clear liquids up until 2 hours makes a big difference in hydration status to the extent that it would help me secure IV access. In the younger child, that might well be the case.
Dr. Epps: Are there any particular concerns for obese pediatric patients that you don’t see as frequently in adults?
Dr. Nafiu: Fortunately, the flip side of this question is more often the case. For example, difficult laryngoscopy is very common in obese adults, but not as common in obese children. Most other issues are pretty similar. I am not sure that we know the relationship between childhood obesity and surgical site infection, although this is a big issue in adult medicine.
Dr. Epps: Orthopaedic surgeons have more time to do a complete preoperative evaluation for elective procedures. What should be our threshold for sending a patient, for example, for a sleep study to screen for sleep apnea or for pulmonary function tests (PFTs)?
Dr. Nafiu: We don’t routinely send pediatric patients for sleep studies or PFTs. These tests are largely operator-dependent, so age and cooperation become important. I’m not aware of any recommendation for PFT studies for children.
Dr. Glass: The biggest issue is sleep apnea and whether these children are at risk for postoperative apnea after outpatient surgery. It’s a controversial area, and we don’t have agreement within the field.
I think being conservative in this area is best. Some obese children may well be at a higher risk for postoperative apnea after what would otherwise be an outpatient procedure. But do all these patients need a sleep test? That is a really expensive proposition. Or should we be admitting the really obese children for 12 to 24 hours after surgery? Or altering the anesthetic management in some other way? Should we have different discharge criteria for the obese patient? We simply do not yet have the answers to these questions.
Dr. Epps: I’ve seen some complications after inpatient procedures as well. Some procedures—such as a posterior spinal fusion with instrumentation—require longer anesthetics and involve more blood loss. What postoperative problems can we expect after these more involved procedures on obese children?
Dr. Glass: The first issue is pain management. What is going to be the easiest way to get these children up and moving? Body weight should not be the sole determinant of pain medication orders. Calculating pain medications requires that we determine lean body mass, which in turn requires using a nomogram to calculate the ideal body weight for the child’s age and height. Pain management is very challenging.
One way that we might avoid using so much opiate for postoperative analgesia would be to use epidural analgesia or peripheral nerve blocks. But those procedures can be much more technically difficult in the obese child, further compounding the challenges in postoperative pain management. Maximizing the use of nonopiate therapies, such as acetaminophen and ketorolac, is preferred whenever practical, because these agents do not cause postoperative respiratory depression.
Dr. Epps: So it sounds like orthopaedists might need to consult the pain service if one is available?
Dr. Glass: For many obese pediatric patients, yes. The other issue to remember is that these children are at risk for postoperative respiratory issues, particularly if they don’t use the incentive spirometer. If they are immobilized and in bed for a long time, the risk of increased oxygen requirement or atelectasis developing in the postoperative period increases. So getting help from the nurses and physical therapists to get them up and out of bed is important.
Another issue that we as pediatric doctors are not accustomed to considering is the risk of deep vein thrombosis (DVT). We currently do not have any firm guidelines that address which obese patients, and at which ages, would require DVT prophylaxis. But clearly, we need to make sure that our patients are mobilized as soon as practical. In addition, sequential compression devices should be used in the operating room and in the early postoperative period.
Also, if an obese child must be house confined for a couple of days, it’s a great opportunity for a nutrition consultation. This also provides the opportunity to engage the patient and the parents with a hospital-based weight control program to help them begin to take some steps, even baby steps, toward a healthier life.
Dr. Epps: I’m a bit skeptical about using BMI as the sole criterion for obesity. What criteria other than inspection can we use to identify patients who might face complications during and after surgery?
Dr. Nafiu: You are right; BMI is clearly not the best descriptor of adiposity. It appears that regional (central) adiposity is more pathogenic. Some studies have looked at the role of neck circumference in predicting perioperative complications, while others have examined the association between abdominal obesity and predicting complications. Neck obesity appears to be quite sensitive for identifying those at risk of perioperative respiratory complications.
Dr. Glass: I share your concerns about using BMI in the preadolescent, but BMI is useful for adolescents. BMI, although an imperfect tool, does help identify at-risk patients. A greater concern is the distribution of the fat, at least as far as the specific challenges that we are likely to have in the operating room go.
We all know that some obese people store all of their fat in their upper chest and thorax area, while others store fat in their hips, buttocks, and legs. We also know that those two groups have different health outcomes.
Dr. Epps: So, if a child looks like he or she might be a problematic surgical patient, what steps should an orthopaedist take?
Dr. Glass: I think that the wisest thing to do would be to refer the patient to the preoperative pain clinic for an assessment. These patients should definitely have a surgical plan in place in advance.
Disclosure information: Dr. Epps—AAOS Now, Pediatric Orthopaedic Society of North America; Drs. Glass and Nafiu—no conflicts.