Aspiration

ApPRIMARY CARE

Primary Care A SPIRATION P NEUMONITIS AND A SPIRATION P NEUMONIA

PAUL E. MARIK, M.B., B.CH.

SPIRATION is defined as the inhalation of oropharyngeal or gastric contents into the larynx and lower respiratory tract.1,2 Several pulmonary syndromes may occur after aspiration, depending on the amount and nature of the aspirated material, the frequency of aspiration, and the host’s response to the aspirated material.2 Aspiration pneumonitis (Mendelson’s syndrome) is a chemical injury caused by the inhalation of sterile gastric contents, whereas aspiration pneumonia is an infectious process caused by the inhalation of oropharyngeal secretions that are colonized by pathogenic bacteria. Although there is some overlap between these syndromes, they are distinct clinical entities (Table 1). Other aspiration syndromes include airway obstruction, lung abscess, exogenous lipoid pneumonia, chronic interstitial fibrosis, and Mycobacterium fortuitum pneumonia.1,2 This article focuses on the pathophysiology, clinical features, and management of aspiration pneumonia and aspiration pneumonitis. Pulmonary aspiration is an important cause of serious illness and death among residents of nursing homes as well as hospitalized patients.1-4 However, the major pulmonary-aspiration syndromes are frequently misdiagnosed and poorly treated. Four common problems are the failure to distinguish aspiration pneumonitis from aspiration pneumonia, the tendency to consider all pulmonary complications of aspiration to be infectious, the failure to recognize the spectrum of pathogens in patients with infectious complications, and the misconception that aspiration must be witnessed for it to be diagnosed.

EPIDEMIOLOGY

A

300,000 to 600,000 people each year in the United States.8-10 Aspiration pneumonia is also common among residents of nursing homes. In one study of patients with nursing home–acquired pneumonia and controls with community-acquired pneumonia, the incidence of...