When a patient undergoes general anesthesia, their ability to breathe and protect their airway is suppressed, making airway management a primary focus for the provider. Two common devices used to maintain a clear path for oxygen are the Laryngeal Mask Airway (LMA) and the Endotracheal Tube (ETT). While both secure the airway, they differ in design and placement, and the choice depends on the patient’s health and the surgical procedure.
Fundamental Device Designs
The primary difference between the Laryngeal Mask Airway and the Endotracheal Tube is their structure and position. The LMA is a supraglottic device, meaning it sits above the glottis (the opening to the larynx). It consists of a tube connected to an elliptical, inflatable mask that creates a seal around the top of the larynx. This design channels air toward the lungs without passing through the vocal cords.
In contrast, the Endotracheal Tube is an infraglottic device placed below the glottis. It is a flexible plastic tube that passes through the mouth, between the vocal cords, and into the trachea. An inflatable cuff near its tip creates a secure seal against the tracheal walls, providing a direct conduit into the lungs.
The Insertion Process
The placement of an LMA or ETT occurs only after the patient is fully unconscious. Placing an endotracheal tube, a procedure known as intubation, requires direct visualization of the patient’s anatomy. The provider uses a lighted instrument called a laryngoscope to gently lift the tongue and epiglottis to expose the vocal cords. The ETT is then guided through this opening into the trachea.
The insertion of a laryngeal mask airway is a less invasive and faster procedure. It is inserted “blindly,” without a laryngoscope, by guiding the deflated mask along the hard palate and into the pharynx. Once in position, the cuff is inflated.
Deciding Which Airway to Use
The selection between an LMA and an ETT is a clinical judgment based on factors related to the patient and the surgical procedure. LMAs are frequently chosen for shorter, less complex procedures where the patient may be breathing on their own with assistance. They are less stimulating to the airway, which can lead to a smoother anesthetic experience with fewer hemodynamic fluctuations.
For longer and more invasive surgeries, particularly those involving the abdomen or chest, an ETT is the standard of care. These procedures often require complete paralysis of the patient’s muscles, necessitating full control of breathing through a mechanical ventilator. The secure seal of the ETT is better suited for positive pressure ventilation. Surgeries that require the patient to be in a position other than flat on their back, such as face-down (prone), also favor an ETT because it is less likely to be dislodged.
A major factor in the decision is the patient’s risk of aspiration, which is when stomach contents enter the lungs. The cuffed ETT provides a much more secure seal within the trachea, offering superior protection against this complication. For this reason, an ETT is almost always used in emergency surgeries where the patient may have a “full stomach” or for patients with conditions that increase aspiration risk, such as GERD or obesity.
Ventilation requirements also guide the choice. Some procedures or patient conditions, like severe lung disease, necessitate delivering breaths at higher pressures to adequately inflate the lungs. An ETT is required in these situations because the seal of an LMA may leak at these higher pressures, preventing effective ventilation.
Post-Procedure Effects and Recovery
After the procedure, the patient’s experience can differ depending on which airway device was used. A sore throat is a common complaint with both, but it is often reported as more frequent or severe following the use of an ETT. This is attributed to the tube passing directly through the sensitive structures of the larynx and vocal cords. Hoarseness of voice is another side effect more commonly associated with endotracheal intubation.
Patients who had an LMA may experience less discomfort and nausea in the immediate postoperative period. The recovery profile with an LMA is often faster, with patients experiencing less coughing as they emerge from anesthesia.
While both devices are very safe, they carry different profiles of less common risks. With an ETT, there is a small risk of damage to the teeth during laryngoscopy or injury to the vocal cords. For an LMA, the primary risk is an inadequate seal, which could lead to ineffective ventilation or gastric insufflation if not recognized and managed promptly.