Pulmonary aspiration

In medicine, aspiration is the entry of secretions or foreign material into the tracheaand lungs. The patient may either inhalethe material, or it may be blown into the lungs during positive pressure ventilationor CPR. As the right main bronchusis more vertical and of slightly wider lumen than the left, aspirated material is more likely to end up in this branch or one of its subsequent bifurcations.

Risk factors

Gastroesophageal reflux, a full stomach, pregnancy, and obesityall increase the risk of aspiration in the semiconscious. Normally fastingfor six hours before elective surgery is enough to empty the stomach. In patients that are injured, gastric emptyingis much slower.

The commonest cause of severe aspiration is reguritation of stomachcontents by semiconscious patients. Patients with neurological conditionsmay also aspirate food or drink.

During labor, early respiratory movements by the baby facilitate filling of alveolar ducts and alveolar lumens with elements of amniotic fluid: amniotic cells, squamesand squamous cells from fetal skin, lanugo, meconium. Reduced inflammatory infiltrate (neutrophils) and capillary congestion is present. Photos at: 1

Consequences

If enough material enters the lungs, the patient may simply drown. However, small volumes of gastric acid contents can fatally damage the delicate lung tissue. Even small volumes of aspirated food may lead to bronchopneumonia. Chronic aspiration may lead to bronchiectasisand may cause some cases of asthma.

Prevention

The lungs are normally protected against aspiration by a series of protective reflexes such as coughingand swallowing. Significant aspiration can only occur if the protective reflexes are absent (in neurological disease, coma, drug overdose, sedationor general anesthesia). In intensive care, sitting patients up reduces the risk of pulmonary aspiration and ventilator associated pneumonia.

Measures to prevent aspiration depend on the situation and the patient. In patients at imminent risk of aspiration, endotracheal intubationby a trained health professionalprovides the best protection.

People with chronic neurological disorders, for example, after a stroke, are less likely to aspirate thickened fluids.

The location of abcesses 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 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 superior segment of the right middle lobe, or the posterior basal segment of the right upper lobe. If one is lying on the left, it goes to the lingula.

See also

• Salt water aspiration syndrome

External links

• Atlas of Pathologyda:Aspiration (medicinsk)

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Pulmonary+aspiration Wikipedia article Pulmonary aspiration.