Safe and Efficient Airway Management

As ASCs tackle more complex cases, anesthesia providers must be prepared for difficult and often unanticipated issues. 

Airway management is one of the most important skills any anesthesia provider should master for one very good reason: Complications from difficult airways and poor management of those airways, though rare, can be life-threatening.

Because proper airway management allows for continuous ventilation and oxygenation during surgery, it’s vital for ensuring successful outcomes. As same-day surgery continues to grow, so too does the use of anesthesia on an outpatient basis. 

Issues often unanticipated

PERSONAL AIRWAYS Every patient your anesthesia providers treat has a unique medical history that must be taken into account before they go under.

Mike MacKinnon, DNP, FNP-C, CRNA, of MacKinnon Anesthesia and Consulting in Arizona and host of the award-winning podcast Anesthesia Deconstructed, emphasizes that being ready for a difficult airway case at any time is crucial for any provider. “It has been estimated that 2.1% of people are difficult to intubate, and 45.7% of these problems are unanticipated,” he says. Over the years, Dr. MacKinnon has been transitioned into new technologies that assist in airway management — even in the most complicated surgeries. He also works with family practices and outpatient centers in rural communities, educating surgical teams about the importance of safe airway management, including what to look for and how to prevent potential catastrophes, which he stresses can very much be life or death situations.

“The complication of not being able to manage an airway with intubation is brain anoxia and death if the patient does not resume spontaneous breathing, which is unlikely with induction doses of drugs,” Dr. MacKinnon says. “For patients with other comorbidities, there is risk of postoperative reintubation and then admission to a hospital.” All of these scenarios are disastrous outcomes for patients who are expecting same-day care.

Prepping for  anesthesia 

When it comes to administering anesthesia, there are a few important considerations to make. First, the American Society of Anesthesiologists (ASA) recommends that anesthesia beyond the level of moderate sedation be administered by certified anesthesiologists, a certified registered nurse anesthetist (CRNA) or an anesthesia assistant under the supervision of a doctor. 

Patients receiving moderate sedation can usually maintain an airway without assistance, though certain equipment should be available at all times in case of emergency, including an oxygen source, nasal cannulas, suction catheters, oral and nasopharyngeal airways, and a means to administer positive pressure ventilation, such as a mask or artificial manual breathing unit (AMBU) bag.

Deep sedation is a different story. It increases the risk of ventilation depression and other potential issues, particularly in patients with comorbidities. Additional equipment may be needed in these cases to assure the surgery is ultimately safe, including laryngoscopes, several sizes of endotracheal tubes (ETTs), laryngeal mask airways (LMAs) and an emergency surgical airway kit.

Patient history and comorbidities

Patient history can be predictive of potential problems during surgery, whether the patient has had complications with anesthesia in the past or they have medical issues that may complicate a surgery and their airway management. In fact, intubation challenges are increasing as more patients with comorbidities are undergoing high-acuity surgeries in outpatient settings.

Dr. MacKinnon says there are several key areas that need to be considered in advance of surgery with patients who may present potential problems. These include — but are not limited to — the following:

• Patients who are on CPAP/BiPAP with high pressure add significant risk, especially those with a CPAP > 12 mmHg. These patients may not be intubation risks — but they are certainly at risk in the post-op care portion of airway obstruction.

• Patients who have BMIs over 40 with comorbidities like HTN, MI, DM, COPD, or those with no major comorbidities with BMIs over 45, can certainly be at risk for difficult airway management.

• Patients with a history of known difficult airway challenges should be examined preoperatively. 

• Pregnant patients potentially have difficult airways.

• Patients with airway/facial deformities present potential risks.

• Difficult endotracheal intubation is expected in elderly patients due to degenerative changes, such as dental loss and head and neck joint changes.

• Previous maxillofacial surgery or tracheostomy comorbidities can impair temporomandibular joint mobility and present problems.

• History of tracheal stenosis should be considered.

• Musculoskeletal system diseases, and the presence of intraoral cavity mass, all have been found to increase difficulties.

Diabetes is another major predictor of a potentially difficult airway.“It’s reported that difficult tracheal intubation is 10 times higher in patients suffering from long-term diabetes mellitus, compared to those without diabetes,” says Dr. MacKinnon.

Pre-operative assessments are vital for patients who are identified with potential risk factors. Some things to look for are inter-incisor gap (IIG) measurements, Mallampati scores, neck mobility and sternomental distance (SMD). “The Cormack-Lehane score (CLS), which is evaluated during the laryngoscopy, also can be used for defining difficult intubation,” says Dr. MacKinnon.

The 6-Ds

The 6-Ds of airway assessment are a common method used to evaluate patients for signs of difficulty:

• Disproportion (tongue to pharyngeal size/Mallampati classification)

• Distortion (e.g., neck mass)

• Decreased thyromental distance (receding or weak chin)

• Decreased interinscisor gap (reduced mouth opening)

• Decreased range of motion of the cervical spine, and

• Dental overbite. “An overlooked and simple clinical sign to assess the jaw is the upper lip bite test,” says Dr. MacKinnon. “The patient is asked to touch their upper lip with their lower teeth — or protrude the mandible. This simple test addresses D3 and D6. Concerning point D5, ask the patient to look up at the ceiling or tilt their head backward. Any launching forward of the patient’s shoulders confirms that the range of motion of the cervical spine is limited.”

Obstructive sleep apnea (OSA) is a breathing disorder than can also complicate airway safety. Characterized by periodic upper airway obstruction during sleep, it can cause a host of issues including episodic hypoxemia and hypercarbia, systemic and pulmonary hypertension, and may lead to cardiovascular morbidity, including arrhythmias and ischemic heart disease.

OSA is more common in men than women and is prevalent in patients who are morbidly obese. It’s also undiagnosed in up to 90% of patients with the condition, putting them at increased risk of anesthesia-related complications. An upper airway abnormality like OSA can result in a challenging mask ventilation and intubation. 
Patients who routinely take sedatives, opioids and inhaled anesthetics can be at risk for ventilatory depression, too, even several days after surgery.

While any one indicator — high BMI, decreased thyromental distance (TMD) — can be a predictor of a difficult airway, multiple factors definitely increase the likelihood of problems. “A combination of more than two parameters predicts expected difficulty better than using a single factor,” says Dr. MacKinnon. “None of these tests are perfect indicators of difficult intubation, but they can certainly make preparation much more effective.”

Smarter technology

Clinical airway management continues to advance at a fast pace. New technology is helping to ensure even the most challenging cases go smoothly.

It has been estimated that 2.1% of people are difficult to intubate, and 45.7% of these problems are unanticipated.
Mike MacKinnon, DNP, FNP-C, CRNA

The latest options in video laryngoscopes, intubating laryngeal mask airways (LMAs) and supraglottic airway devices contribute to safer care by helping anesthesia providers maintain ventilation and oxygenation during difficult cases and routine procedures. Video laryngoscopy, for instance, allows the larynx to be viewed indirectly using a tiny imaging device. It can lower costs when it comes to elective surgeries by reducing stays for patients.

Flexible intubation scopes have been around for decades, but are still considered to be among the most versatile tools in a surgery toolbox, says Dr. MacKinnon. These scopes can navigate around airway masses and can be used on patients who are lightly sedated. Newer versions now include fiberoptic and video chip technology that improve overall image quality. There are also disposable versions.

Supraglottic airway devices can be inserted into the pharynx to allow ventilation, oxygenation and administration of anesthetic gases without the need for endotracheal intubation. These are useful when facemask ventilation is difficult, or even as a conduit for endotracheal intubation.

The most commonly used devices in the OR tend to be laryngeal mask airways (LMAs), as well as Combitube, laryngeal tubes and pharyngeal tubes. The LMAs use a hollow shaft (or tube) connected to a mask-like cuff designed to sit in the hypopharynx facing the glottis with the tip at the esophageal inlet. OSM