August 5, 2021

Anesthesia providers rely on several techniques to assist them during procedures.

A BETTER VIEW Video laryngoscopes are invaluable tools for anesthesia providers as they navigate difficult airways.

Intubating patients can be visually and physically demanding for anesthesia providers, especially when working with obese patients. On top of that, providers are now protecting themselves with multiple layers of PPE, further complicating the job.

In situations such as these, anesthesia providers are relying more than ever on video laryngoscopes, which provide direct views of the glottis to make intubation easier. The latest video laryngoscopes are more ergonomic and portable than ever before, while also featuring high-definition imaging, notes Michael Aziz, MD, a professor of anesthesiology and medicine at Oregon Health & Science University in Portland. “Providers often use standard blades for routine intubations and acute angle blades to secure anticipated difficult airways,” he says.

Dr. Aziz also notes that humidified high-flow nasal oxygenation, which is commonly used in intensive care units as a bridge to intubation, is becoming more popular for managing difficult airways. “Providers can deliver 70 liters of oxygen quite comfortably, and they avoid intubation and effectively maintain oxygenation for shorter duration procedures,” he says.

Anesthesia providers should always be on the lookout for red flags, says Roxanne McMurray, DNP, APRN, CRNA, a clinical assistant professor at the University of Minnesota School of Nursing. She recommends that providers utilize the STOP-BANG questionnaire, an eight-question tool that can help predict sleep apnea risk factors, as well as determine the likelihood of a patient’s airway obstructing.

Providers should also determine the patient’s Mallampati classification (Class I through Class IV). “The rating is based on tongue and pharyngeal size, and visualization of the uvula or soft palette,” she says. Providers should also check the distance from the chin to the thyroid cartilage. “If it’s less than three finger breadths, intubation could prove challenging,” notes Dr. McMurray.

The first step when caring for larger individuals should always be proper ramped positioning.

BIG CHALLENGE Anesthesia providers must make special considerations to provide the best and safest care to individuals with high BMI.

For anesthesia providers, airway management in obese and morbidly obese patients presents an array of challenges and requires special care and attention. Luckily, a simple positioning precaution can help with everything from lowering patient safety risks to increasing the chances of a successful first attempt intubation.

In his 2018 paper on the subject, Craig A. Troop, MD, elaborates on preferable positioning practices for patients who fall into the category of obese (BMI > 30) or morbidly obese (BMI > 40). According to Dr. Troop, a simple yet significantly effective intervention for these patients is to position them in the head-elevated laryngoscopy position (HELP), as opposed to a fully supine position.

Also referred to as the ramped position, HELP allows for the alignment of all three airway axes in obese patients, which is critical in airway management. “To facilitate placement of the endotracheal tube, one needs to align the oral, the pharyngeal and the laryngeal axis to improve the ‘line of site’ from the mouth to the trachea,” writes Dr. Troop. In addition to specially sculptured foam positioning aids that are available to achieve the HELP position, these patients also can be positioned by using a “head cradle” on a ramp of stacked blankets, also referred to as "stacking."

Regardless of how providers achieve the HELP position, the important thing is that they do it. Not only does proper positioning reduce anxiety in obese patients — many heavy individuals complain they can’t breathe in a fully supine position — it also lengthens the desaturation safety period, which is critical for safe anesthesia and airway management. Dr. Troop adds that HELP results in a greater incidence of successful first attempt intubations.

Proper positioning of these high-risk patients is key to patient safety and successful outcomes.

Credit: Bone Foam Inc.
The Troop Elevation Pillow helps align the upper airway axes for obese patients.

Any type of surgery performed on obese patients takes extra caution and extra measures to achieve consistently successful outcomes in outpatient facilities. Among the measures that reduce the risk for injuries and negative outcomes are tools that work to aid airway management and help assure best positioning practices for this patient population.

Obesity rates are climbing in the United States and the Centers for Disease Control and Prevention (CDC) reports that more than 30% of the adult U.S. population is now considered obese.

According to CDC, people with a BMI of 30 kg/m2 to < 35 kg/m2 are classified as Class I obese, people with a BMI of 35 kg/m2 to < 40 kg/m2 are classified as Class 2 obese, and people with a BMI of 40 kg/m2 or higher are classified as Class 3 extremely obese. Obesity is associated with significant physiologic cardiovascular and pulmonary changes. The position in which the patient is placed during surgery can further alter cardiovascular and pulmonary function.

The risks for this population are considerable and even moderate obesity is associated with risk in surgery. According to the AORN's Guidelines for Positioning the Patient, "Airway and breathing mechanisms are compromised in patients who are obese because of excess adipose tissue leading to an increased workload for the supportive muscles; increased oxygen consumption and carbon dioxide production; decreased myocardial compliance (i.e., 35% of normal); increased breathing effort and decreased efficiency of air exchange; decreased resting functional residual lung capacity; and increased incidence of gastroesophageal reflux, hiatal hernia, and abdominal pressure that adds to the risk for aspiration."¹

The positioning of these patients is important since obese patients may have difficulty breathing in a recumbent position. Elevating the patient’s head and neck helps establish a patient airway. Using a wedge-shaped positioning device that supports the head and shoulders helps prevent strain on the patient's arms and brachial plexus.

Positioning solutions such as the Troop Elevation PillowTM (T.E.P.) for Anesthesia positioning can solve the challenges associated with these high-risk patients. The use of this pillow quickly achieves H.E.L.P. (head elevated laryngoscopy position) to lower risk and improve patient safety.

H.E.L.P. is when the head is visibly above the shoulders with horizontal alignment between the external auditory meatus and sternal notch. This improves the view during laryngoscopy compared to the sniffing position in obese patients.² Other benefits include better preoxygenation and easier bag-mask ventilation in obese patients.³

The successful positioning of the obese patient is paramount to successful surgery, so OR teams will give these patients special consideration throughout the procedure.

Note: For more information, please go to www.bonefoam.com

Methods of intubation and drug dosing remain topics of debate.

The altered anatomy and physiology of morbidly obese patients makes their anesthetic management challenging, so perhaps it’s little surprise that controversies surrounding the handling of these patients abound. A 2018 study by a doctor at Stanford School of Medicine’s anesthesiology department reviewed relevant — and sometimes conflicting — medical literature about recent advances in anesthesia for obese patients in an attempt to clarify how to best care for these patients.

One study about airway management reviewed in the paper by Stanford's Jay Brodsky, MD, found that while moderate obesity might place patients at a higher risk for a difficult tracheal intubation than a lean patient, the magnitude of the risk doesn’t rise proportionally in the morbidly obese.

The study defines difficult tracheal intubation as the need for more than one attempt with direct laryngoscopy (DL). Literature reviewed by Dr. Brodsky showed divergent opinions as to whether video-assisted laryngoscopy (VAL) would be a preferable routine approach for tracheal intubation. "Many believe that VAL reduces the number of failed intubation attempts by improving the glottic view while also reducing laryngeal/airway trauma," he writes. "However, a recent meta-analysis failed to demonstrate that VAL, when compared to conventional DL, actually decreased the number of intubation attempts or the incidence of hypoxia or respiratory complications."

Dr. Brodsky also reviewed studies that discussed drug dosing, and whether the amount of propofol used in obese patients should be based on total body weight (TBW) or lean body weight (LBW). One study concluded that a dosage based on TBW could be dangerously high and recommended using LBW as a dosage guide. A subsequent study challenged that notion, saying that LBW isn't a useful dosage gauge because patients hooked up to a brain function monitoring device were shown to need more propofol to be sedated than the amount suggested based on their LBW.

Additionally, Dr. Brodsky reported, several studies showed that high doses of sugammadex to reverse neuromuscular blockade recommended by the drug’s manufacturer are unnecessary and expensive in morbidly obese patients. Multiple studies showed that doses significantly lower than the manufacturer-recommended amounts successfully reduced neuromuscular blockade in obese patients.

While opinions vary on optimal strategies, Dr. Brodsky says the literature at least shows that techniques used for patients within normal weight ranges could be inappropriate and unsafe for people who are obese.

Preoperative collaboration and consensus is crucial to avoid adverse intraoperative events involving obese patients with difficult airways.

When it comes to airway management, ENT procedures present a unique challenge, as both the surgeon and the anesthesia provider are working in the same area. A recent article examined the communication issues between these two providers with the goal of eliminating intraoperative disagreements and danger.

The paper, published last year in AMA Journal of Ethics, centered on the case study of a 52-year-old woman with a hoarse voice and trouble swallowing who had a history of obesity and obstructive sleep apnea. She couldn’t lay flat without shortness of breath due to a large benign thyroid mass that deviated her trachea and narrowed its oral opening. The patient elected to undergo a total thyroidectomy.

Discussing an airway plan, the anesthesiologist recommended fiberoptic intubation — a more conservative, less risky approach to securing the airway that would keep the patient awake and breathing on her own while her breathing tube was placed and secured prior to general anesthesia induction. The surgeon, however, feared the patient would feel terrified and panic during fiberoptic intubation, and the junior anesthesiologist deferred to the surgeon’s plan to rapidly secure her airway via a rigid bronchoscope.

With the patient in a 45-degree head-up position, the anesthesiologist administered anesthetics and paralytics and placed an oral airway but had difficulty securing it. The provider implemented a two-handed technique to mask ventilate the patient, but oxygen saturation continued to fall. Direct laryngoscopy was then attempted, but the vocal cords could not be visualized.

After another failed attempt at mask ventilation, the surgeon attempted several times to place the airway via rigid bronchoscope, but the patient’s oxygen saturation, blood pressure and heart rate fell, indicating looming cardiac arrest. Finally, the airway was secured, the patient stabilized and the surgery proceeded. Both providers were relieved but shaken, and resolved to examine the event and see how they could better collaborate.

The authors say this example illustrates the need for better preoperative communication between surgeons and anesthesiologists. "All team members' concerns should be voiced, heard, considered and addressed well in advance of surgery on a patient to allow time for good decision making and inclusive discussion, confirmation of available equipment, and an organized approach to managing a patient's care," they write. "In particular, the patient’s airway management plan needs to be discussed by the surgeon and anesthesiologist and agreed upon before a patient is taken to the operating room."

The authors say the unique skill sets of the surgeon and the anesthesiologist should be respected. "The anesthesiologist’s communication of a pharmacological approach to sedation during an attempted awake fiberoptic intubation might alleviate the surgeon’s concerns about patient comfort," they say of the case study. "Alternatively, a surgeon’s adeptness and experience with an available rigid bronchoscope might mitigate an anesthesiologist's concerns that a patient remain spontaneously ventilating during the induction process." They add that the patient should also be aware of and sign off on the airway plan.

"Despite its high-stakes implications for patient safety, operating room communication remains under researched," the authors say. "Surgeon-anesthesiologist relationships might be the most central factor in determining how effectively operating room teams function. As the case highlights, the dynamics between these two physicians — who might share, yield or compete for leadership in operating room settings — can ultimately facilitate or impede success."

They say intraoperative and postoperative airway management decisions should be informed by relevant considerations of a patient’s anatomy, likelihood of success with any planned strategy, image review and contingency planning. They encourage surgeons and anesthesiologists to better understand and appreciate their successes, learn from their mistakes, optimize their interdisciplinary relationships, and foster collaboration and a sense of accountability and collective ownership of patients' safety and care.