A nasopharyngeal airway (NPA) is a temporary medical device used to manage breathing difficulties in a person who is struggling to keep their own airway open. The device is commonly referred to as a “nasal trumpet” due to its distinct, flared end. The NPA provides a quick, non-invasive method for improving oxygenation and ventilation, particularly in patients with an altered level of consciousness.
Defining the Nasopharyngeal Airway and Its Structure
The nasopharyngeal airway is a hollow tube, typically constructed from soft, flexible materials like rubber, silicone, or plastic. The device is sized using the French catheter scale, with common adult sizes ranging from 28 to 36 French, representing the diameter of the tube.
The tube features a beveled tip at the insertion end, designed to minimize friction and tissue damage as it is advanced through the nostril. The opposite end has a flared ring or flange that rests against the patient’s nostril once inserted. This flange prevents the airway adjunct from slipping completely into the nasal cavity.
The NPA is inserted into one nostril and advanced along the nasal floor until its tip rests in the posterior pharynx. The device must be appropriately sized so that its tip is positioned near the epiglottis, the flap of cartilage that covers the windpipe, to effectively bypass any obstruction.
Primary Function: Why Airway Patency is Critical
Airway patency refers to the condition of the airway being open and unobstructed, which is necessary for effective breathing. When a person loses consciousness, the muscles in the jaw, tongue, and throat relax. This allows the tongue and soft tissues to fall backward against the posterior wall of the pharynx, creating a mechanical blockage.
The nasopharyngeal airway solves this problem by acting as a rigid, open channel that holds the soft tissues away from the back of the throat. By extending past the tongue and soft palate, the NPA ensures a clear passage for air exchange.
The NPA bypasses the area where obstruction is most likely to occur, maintaining a continuous path for ventilation. Since the device does not stimulate the gag reflex, it can be used safely in semi-conscious patients who still have protective airway reflexes intact, unlike oral airway devices that could trigger vomiting and aspiration.
Indications: When is the NPA Necessary?
The NPA is the preferred choice for patients who need an open airway adjunct but cannot tolerate an oral airway due to a functioning gag reflex. This includes semi-conscious patients with altered mental status or those who cannot open the mouth or access the oral cavity, such as patients with trismus (lockjaw) or significant oral or maxillofacial injury. In these scenarios, the nasal route provides the only viable option.
The device can facilitate frequent suctioning in patients unable to clear their own secretions. The hollow tube allows a suction catheter to be passed directly into the posterior pharynx to remove blood, mucus, or other obstructing fluids. This is useful for patients with neurological impairment or those recovering from certain surgeries.
Contraindications: Safety Concerns and When Not to Use the NPA
The most significant contraindication for NPA use is a suspected or confirmed basilar skull fracture or severe mid-face trauma. These fractures involve the bones at the base of the skull, which separate the brain cavity from the nasal passages.
Inserting an NPA with this type of trauma risks the tube inadvertently traveling through the fractured bone and into the brain cavity. Medical professionals look for signs of a basilar skull fracture before attempting insertion. These signs include bruising around the eyes (raccoon eyes) or behind the ears (Battle’s sign), or leakage of cerebrospinal fluid from the nose or ears.
Another risk is nosebleeds, or epistaxis, which occurs in a substantial percentage of insertions. The NPA can injure the nasal mucosa during placement, especially if the patient has a blood clotting disorder or is taking anticoagulant medication. If bleeding occurs, it can potentially lead to the aspiration of blood, complicating the patient’s respiratory status.