Precautions for clinical application of laryngeal mask airway

Laryngeal mask airway (LMA) is a ventilation tool that intervenes between endotracheal intubation and mask, which can not only allow patients to breathe spontaneously, but also perform positive pressure ventilation. The laryngeal mask is widely used in clinical anesthesia, emergency resuscitation and difficult airway management due to its simple operation and reliable effect.

▶Indications and contraindications for laryngeal mask airway application

Indications

1. Surgery without the risk of vomiting and reflux, especially in patients with difficult endotracheal intubation.

2. When difficult intubation forces the use of a laryngeal mask (LMA), the laryngeal mask can be used as a guide for endotracheal intubation.

3. Fiberoptic bronchoscope laser cauterization of vocal cords, trachea or small tumors in the bronchus can be performed through the laryngeal mask.

4. Laryngeal mask can be used for patients with unstable cervical spine who need to move their head but have great concerns.

5. Laryngeal mask is suitable for ophthalmic surgery, because it is less likely to cause increased intraocular pressure, less coughing and vomiting after surgery, less reaction to pulling out the laryngeal mask, and less fluctuation of intraocular pressure.

6. The laryngeal mask can be used during emergency resuscitation. If the operation is skilled, effective ventilation can be quickly established, and the effect is exact.

7. Suitable for body surface, limb general anesthesia surgery and laparoscopic abdominal surgery that do not require muscle relaxation.

Contraindications

1. Infection or other pathological changes in the throat

2. There is a risk of reflux and aspiration: such as hiatal hernia, pregnancy, intestinal obstruction, acute abdomen, thoracic injury, patients with severe trauma and a history of reflux of gastric contents.

3. Airway obstruction that may occur after anesthesia in patients with tracheal compression and tracheomalacia.

4. Positive pressure ventilation for patients with full stomach and obesity, positive pressure ventilation for patients with chronic obstructive pulmonary disease (COPD), single-lung ventilation for thoracotomy, long-term neurosurgery, patients with high airway secretion, etc.

▶Model selection of laryngeal mask airway

Optimal sealing of the laryngeal mask airway depends on many factors, including device size, cuff inflation status, and patient anatomy, so predicting the optimal size is complicated.

If a larger cuff volume is required to maintain a seal, we usually switch to a larger size LMA. With a larger LMA, a better seal may be achieved with less air charge. Using too small a device and overinflation of the cuff may result in a poor fit within the oropharyngeal space and may also cause damage to the oropharyngeal mucosa.

In general, a size 4 LMA is suitable for most adult women, and a size 5 LMA is suitable for adult men weighing up to 100kg. In many cases, if adequate ventilation is not achieved with the initially selected LMA model, a different model of LMA should be tried.