In medicine, aspiration is the entry of secretions or foreign material into the trachea and lungs. The patient may either inhale the material, or it may be blown into the lungs during positive pressure ventilation or CPR. As the right main bronchus is 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 obesity all increase the risk of aspiration in the semiconscious. Normally fasting for six hours before elective surgery is enough to predictable empty the stomach. In patients that are injured, gastric emptying is much slower.

The commonest cause of severe aspiration is reguritation of stomach contents by semiconscious patients. Patients with neurological conditions may also aspirate food or drink.

Consequences

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

Prevention

The lungs are normally protected against aspiration by a series of protective reflexes such as coughing and swallowing. Significant aspiration can only occur if the protective reflexes are absent (in neurological disease, coma, drug overdose, sedation or 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 intubation by a trained health professional provides the best protection.

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

See also Salt water aspiration syndrome