Foetor hepaticusR19.6

Synonyms

Liver respiration;

Definition

Foetor hepaticus is one of the signs of advanced liver disease (Kasper 2015). It is a slightly sweet, ammonia-smelling foetor ex ore during exhalation (Kasper 2015 / Calenic 2014). The odor is comparable to raw liver (Herold 2022).

Foetor hepaticus is foetor ex ore, the latter is also known as halitosis. 80-90% of foetor ex ore is caused by local processes (Herold 2022) in the mouth, nose and throat, with pulmonary diseases in second place, followed by gastrointestinal diseases of the stomach and esophagus. Only then do metabolic diseases follow as a cause (Messmann 2012).

Foetor hepaticus can occur from stage 3 of the West Haven classification of hepatic encephalopathy and is usually always present in stage 4 (Fobbe 2020).

There is an increase in ammonia concentration(NH3, a neurotoxin [Canbay 2011]) in the blood and in the breath in foetor hepaticus, both of which are positively correlated (Shimamoto 2000).

Foetor hepaticus occurs:

- in coma hepaticum

- in hepatic encephalopathy

- in acute liver failure (Herold 2022).

It may also occur in the setting of other diseases with liver involvement such as Crimean-Congo hemorrhagic fever (Muco 2018).

Foetor hepaticus results from the inability of the liver to metabolize methionine and mercaptan dimethyl sulfide. Thus, these substances enter the lungs and are exhaled from there. Trimethylamine is also thought to be involved in the odor (Dennis 2019).

Formation of mercaptan exacerbates damage to the liver parenchyma (Grosse- Brockhoff 1969).

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