Fink Effect
Encyclopedia
The Fink effect, also known as "diffusion anoxia", "diffusion hypoxia",
or the "third gas effect",
is a factor that influences the Po2 (partial pressure of oxygen)
within the alveolus. When soluble gases are breathed in (e.g. nitrous oxide
, N2O) large quantities can be dissolved
in body
fluids rapidly. This can lead to a temporary
increase in the concentration
of oxygen
and carbon dioxide
in the alveolus, causing an increase in their respective partial pressures.
The effect is named for Bernard Raymond Fink
(1914–2000), whose 1955 paper first explained it.
When a patient is recovering from N2O anaesthesia, large quantities of this gas cross from the blood into the alveolus (down its concentration gradient) and so for a short period of time, the O2
and CO2
in the alveolus are diluted by this gas. This could potentially cause the partial pressure of oxygen to decrease and could temporarily lead to hypoxia
. The decrease in CO2 could also potentiate this effect as ventilation
would be suppressed, leading to potential hypoxaemia. Nonetheless, this effect would only last a couple of minutes and hypoxia can be avoided by increasing the fractional inspired oxygen concentration when recovering from N2O anaesthesia.
or the "third gas effect",
is a factor that influences the Po2 (partial pressure of oxygen)
Oxygen saturation
Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...
within the alveolus. When soluble gases are breathed in (e.g. nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
, N2O) large quantities can be dissolved
Dissolution (chemistry)
Dissolution is the process by which a solid, liquid or gas forms a solution in a solvent. In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent. For liquids and gases, the molecules must be compatible...
in body
Body
With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...
fluids rapidly. This can lead to a temporary
Temporary
Temporary may refer to:Computing* Temporary variable* Temporary file* Temporary folder* Temporary filesystemOther uses* Temporary work, a common working arrangement...
increase in the concentration
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the alveolus, causing an increase in their respective partial pressures.
The effect is named for Bernard Raymond Fink
Bernard Raymond Fink
Bernard Raymond Fink was a British physician.Fink was born in London, brought up in Antwerp, Belgium, and emigrated to the USA in 1950. He was bestowed ASA Excellence in Research Award in 1987. He was the secretary of the International Association for the Study of Pain and the President of the...
(1914–2000), whose 1955 paper first explained it.
When a patient is recovering from N2O anaesthesia, large quantities of this gas cross from the blood into the alveolus (down its concentration gradient) and so for a short period of time, the O2
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the alveolus are diluted by this gas. This could potentially cause the partial pressure of oxygen to decrease and could temporarily lead to hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
. The decrease in CO2 could also potentiate this effect as ventilation
Ventilation (physiology)
In respiratory physiology, ventilation is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:-Sample values:...
would be suppressed, leading to potential hypoxaemia. Nonetheless, this effect would only last a couple of minutes and hypoxia can be avoided by increasing the fractional inspired oxygen concentration when recovering from N2O anaesthesia.