Pulmonary aspiration is the entry of material such as pharyngeal secretions, food or drink, or stomach contents from the oropharynx or

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...

, into the

larynx The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about ...

(voice box) and lower respiratory tract, the portions of the

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies g ...

from the

trachea The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from t ...

(windpipe) to the lungs. A person may inhale the material, or it may be delivered into the

tracheobronchial tree The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose t ...

during positive pressure ventilation. When pulmonary aspiration occurs during eating and drinking, the aspirated material is often colloquially referred to as "going down the wrong pipe". Consequences of pulmonary aspiration range from no injury at all, to

chemical pneumonitis Chemical pneumonitis is inflammation of the lung caused by aspirating or inhaling irritants. It is sometimes called a "chemical pneumonia", though it is not infectious. There are two general types of chemical pneumonitis: acute and chronic. Irri ...

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severit ...

, to death within minutes from asphyxiation. These consequences depend on the volume, chemical composition, particle size, and presence of infectious agents in the aspirated material, and on the underlying health status of the person. In healthy people, aspiration of small quantities of material is common and rarely results in disease or injury. People with significant underlying disease or injury are at greater risk for developing respiratory complications following pulmonary aspiration, especially hospitalized patients, because of certain factors such as depressed level of consciousness and impaired airway defenses ( gag reflex and

respiratory tract antimicrobial defense system The respiratory tract antimicrobial defense system is a layered defense mechanism which relies on components of both the innate and adaptive immune systems to protect the lungs and the rest of the respiratory tract against inhaled microorganisms. ...

). The lumen of the

right main bronchus A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronch ...

is more vertical and slightly wider than that of the left, so aspirated material is more likely to end up in this bronchus or one of its subsequent bifurcations. About 3.6 million cases of pulmonary aspiration or foreign body in the airway occurred in 2013.

Presentation

Consequences

Particle-related

Pulmonary aspiration of particulate matter may result in acute airway obstruction which may rapidly lead to death from arterial hypoxemia.

Acid-related

Pulmonary aspiration of acidic material (such as stomach acid) may produce an immediate primary injury caused by the

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...

of acid with lung parenchyma, and a later secondary injury as a result of the subsequent inflammatory response.

Bacterial

Pulmonary aspiration may be followed by bacterial pneumonia. Community-acquired aspiration pneumonia is usually caused by

anaerobic bacteria An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenat ...

, whereas hospital-acquired aspiration pneumonia is more often caused by mixed flora, including both aerobic and anaerobic bacteria.

Death

Pulmonary aspiration resulting in pneumonia, in some patients, particularly those with physical limitations, can be fatal. Famous people like John Bonham have died of it.

Risk factors

Risk factors for pulmonary aspiration include conditions which depress the level of consciousness (such as traumatic brain injury,

alcohol intoxication Alcohol intoxication, also known as alcohol poisoning, commonly described as drunkenness or inebriation, is the negative behavior and physical effects caused by a recent consumption of alcohol. In addition to the toxicity of ethanol, the main ...

drug overdose A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended.

, and

general anesthesia General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of consciousness that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general ...

). A decreased gag reflex, upper esophageal sphincter and lower esophageal sphincter tone, gastroesophageal reflux, full stomach, as well as

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

, stroke, and

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...

can all increase the risk of aspiration in the semiconscious.

Tracheal intubation Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequentl ...

or presence of a gastric tube (for example, a feeding tube) may also increase the risk.

Prevention

The lungs are normally protected against aspiration by a series of ''protective reflexes'' such as coughing and

swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. Swallowing i ...

. Significant aspiration can only occur if the protective reflexes are absent or severely diminished (in neurological disease,

coma A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...

drug overdose A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended.

sedation Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, ...

). In intensive care, sitting patients up reduces the risk of pulmonary aspiration and ventilator-associated

. Measures to prevent aspiration depend on the situation and the patient. In patients at imminent risk of aspiration,

tracheal intubation Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequentl ...

by a trained

health professional A health professional, healthcare professional, or healthcare worker (sometimes abbreviated HCW) is a provider of health care treatment and advice based on formal training and experience. The field includes those who work as a nurse, physician (suc ...

provides the best protection. A simpler intervention that can be implemented is to lay the patient on their side in the

recovery position In first aid, the recovery position (also called semi-prone) is one of a series of variations on a lateral recumbent or three-quarters prone position of the body, often used for unconscious but breathing casualties. An unconscious person, a per ...

(as taught in

first aid First aid is the first and immediate assistance given to any person with either a minor or serious illness or injury, with care provided to preserve life, prevent the condition from worsening, or to promote recovery. It includes initial i ...

and

CPR Cardiopulmonary resuscitation (CPR) is an emergency procedure consisting of chest compressions often combined with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore spont ...

classes), so that any

vomitus Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenterit ...

produced by the patient will drain out their mouth instead of back down their

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its st ...

. Some anesthetists will use

sodium citrate Sodium citrate may refer to any of the sodium salts of citric acid (though most commonly the third): * Monosodium citrate * Disodium citrate * Trisodium citrate The three forms of salt are collectively known by the E number E331. Applications ...

to neutralize the stomach's low pH and metoclopramide or

domperidone Domperidone, sold under the brand name Motilium among others, is a dopamine antagonist medication which is used to treat nausea and vomiting and certain gastrointestinal problems like gastroparesis (delayed gastric emptying). It raises the l ...

(pro-kinetic agents) to empty the stomach. In veterinary settings, emetics may be used to empty the stomach prior to sedation. Due to growing issues with patients not complying with fasting recommendations before surgery, some hospitals will now also routinely administer emetics prior to anesthesia. Newer operating rooms are often equipped with dedicated vomitoria for this purpose. People with chronic

neurological disorder A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakn ...

s, for example, after a stroke, are less likely to aspirate

thickened fluids Thickened fluids and thickened drinks are often used for people with dysphagia, a disorder of swallowing function. The thicker consistency makes it less likely that individuals will aspirate while they are drinking. Individuals with difficulty sw ...

on an instrumental swallowing assessment. However, this does not necessarily translate into reduced risk of pneumonia in real life eating and drinking. Also, pharyngeal residue is more common with very thickened fluids: this may subsequently be aspirated and lead to a more severe pneumonia.Robbins J, Gensler G, Hind J, Logemann JA, Lindblad AS, Brandt D, et al. Comparison of 2 interventions for fluid aspiration on pneumonia incidence: a randomised trial. Ann Intern Med. 2008;148:509–18. The location of

abscess An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends ...

es caused by aspiration depends on the position one is in. If one is sitting or standing up, the aspirate ends up in the posterior basal segment of the right lower lobe. If one is on one's back, it goes to the superior segment of the right lower lobe. If one is lying on the right side, it goes to the posterior segment of the right upper lobe, or the posterior basal segment of the right upper lobe. If one is lying on the left, it goes to the lingula.

References

External links

Atlas of Pathology
{{Authority control Airway management Anesthesia Intensive care medicine Lung disorders