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Aspiration Pneumonitis/Mendelson's Syndrome

Not to be confused with aspiration pneumonia which is caused by inhaling of pneumonia-causing bacteria, aspiration pneumonitis, also known as Mendelson's Syndrome , is a result of aspiration (or breathing in) of the regurgitated contents of the stomach and gastric juices into the respiratory tract. This happens during a period of unconsciousness while the gag reflex is suppressed, for example while under anesthesia for surgery or childbirth.

Regurgitation of gastric contents with aspiration into the lungs contributes significantly to the morbidity and mortality rates of surgeries. The result of inhaling gastric contents into the larynx and lower lungs causes serious injury and may result in death. This is one of the reasons that fasting is required before surgery, in order to ensure that the stomach is empty to minimize the risk of aspiration pneumonitis. It is also one of the reasons that pregnant women are particularly at risk, because there is rarely enough notice for pre-procedure fasting unless a C-section has been scheduled in advanced.

Aspiration pneumonitis carries a 30-percent mortality rate and accounts for up to 20 percent of all deaths attributable to anesthesia .

The most important thing to know about aspiration pneumonitis is this: Aspiration pneumonitis can be prevented ! Careful monitoring during anesthesia, proper airway management and absolutely careful precautions before surgery can minimize or eliminate risk. When aspiration pneumonitis takes place during surgery, it is almost always a result of incompetent pre-surgical intake or improper management during surgery.


Aspiration pneumonitis can progress rapidly and within hours. Symptoms of rapid breathing, oxygen deprivation and fever may develop. Cardiac failure can easily result. A secondary infection may also develop.

However, the symptoms of aspiration pneumonitis do not always show up immediately and sometimes do not appear until two to five hours following aspiration. Symptoms can also vary widely. Sometimes patients who aspirate gastric material show extreme signs of distress such as wheezing, coughing, shortness of breath, fluid in the lungs, low blood pressure, hypoxemia (low blood oxygen), severe acute respiratory distress syndrome and death. The bron chopulmonary reaction may include turning blue, pulmonary wheezing and rattling, decreased arterial oxygen, and rapid heartbeat. Fluid in the lungs can cause sudden death or death may occur later from pulmonary complications.

Other times, however, patients have only a cough or a wheeze, and some patients have what is commonly referred to as silent aspiration. In a significant study of 67 patients who aspirated while undergoing anesthesia, 42 of them (63%) had no symptoms. Of the 25 who had symptoms, 13 required ventilator support and four of them died. "Silent" aspiration may be the cause of unexplained cases of postoperative pulmonary dysfunction.


Dr. Curtis L. Mendelson determined that it was the acid content of the gastric contents that caused the most serious damage to the lungs; in fact he likened the acidity of the stomach contents to that of hydrochloric acid. Breathing gastric contents into the lungs results in what is, in effect, a chemical burn through the trachea, the bronchial passages and into the lungs. But acidity alone is not responsible for all aspiration pneumonitis injuries. The presence of food particles inhaled into the lungs also causes damage. The quantity of vomitus is also a factor in the severity of the reaction.

Aspiration of gastric contents can cause a broad range of damage, from very mild to severe, including adult respiratory distress syndrome (ARDS) that has a high degree of morbidity and mortality. Aspiration pneumonitis also predisposes its victims to subsequent bacterial pulmonary infection. One-third of patients will experience secondary complications. Twenty percent of deaths attributable to anesthesia are due to aspiration pneumonitis.

Increased Risk

Certain populations and conditions present greater risk for aspiration pneumonitis than others; and competent medical personnel should take that into account. Some examples include:

Prevention and Aspiration Pneumonitis Malpractice

Because aspiration pneumonitis can be prevented, when aspiration pneumonitis takes place during surgery, it is almost always a result of some form of medical negligence or medical malpractice, including incompetent pre-surgical intake or errors in airway management and anesthesia during surgery.

From some points of view, there is really no excuse for aspiration pneumonitis and its complications to occur. Enforcement of pre-surgical fasting protocols (which are different for children and adults); re-scheduling surgery if protocols were not strictly followed, careful monitoring of the airways during unconsciousness, and proper intake and precautions during surgery can minimize or eliminate risk of aspiration pneumonitis during anesthesia. Even in patients who must undergo unplanned surgery, prophylactic measures can minimize risk. Both the volume and acidity of gastric contents can be reduced with appropriate drugs and stomach contents can be emptied.

Controlling the risk factors includes making sure that the stomach is empty; that if there are stomach contents, the acid ph is in an acceptable range and the volume is under the danger zone; and checking for the function of the lower esphogeal sphincter and peristalsis. Preventative techniques include nasogastric decompression, acid neutralization, acid suppression, and increased gastric peristalsis. There are also drugs that minimize the risks. Proper risk management also includes protective airway management practices (e.g., mandatory use of suction and skill in laryngoscopy).

Despite clear protocols for prevention of aspiration pneumonitis, this condition still remains one of the major risks of surgery involving general anesthesia. Instances of aspiration pneumonitis almost indicate some form of medical negligence or medical malpractice.

If you or a loved one has suffered from aspiration pneumonitis, please call or e-mail us today and we will evaluate your aspiration pneumonitis claim for free.

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