Fink effect

The Fink effect, also known as "diffusion anoxia",^[1] "diffusion hypoxia",^[2] or the "third gas effect",^[3] is a factor that influences the pO₂ (partial pressure of oxygen) within the alveolus. When soluble gases (e.g. nitrous oxide, N₂O) are breathed in large quantities they 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.^[1]^[4] 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.^[5]

References

1 2 J. Roger Maltby (2002). Notable names in anaesthesia. Royal Society of Medicine Press. p. 63. ISBN 978-1-85315-512-3.
↑ S. Ahanatha Pillai (2007). Understanding Anaesthesiology. Jaypee Brothers Publishers. p. 101. ISBN 978-81-8448-169-3.
↑ Steven M. Yentis, Nicholas P. Hirsch, and Gary B. Smith (2009). Anaesthesia and Intensive Care A–Z: An Encyclopedia of Principles and Practice. Elsevier Health Sciences. ISBN 978-0-443-06785-3.
↑ B. R. Fink (1955). "Diffusion anoxia". Anesthesiology 16 (51): 1–519. doi:10.1097/00000542-195507000-00007.
↑ Andrew B. Lumb, John Francis Nunn (2005). Nunn's applied respiratory physiology (6th ed.). Elsevier/Butterworth Heinemann. p. 169. ISBN 978-0-7506-8791-1.

Anesthesia (outline)

Types	General Spinal Epidural Conduction anesthesia Local Topical Intercostal nerve block Sedation / Twilight anesthesia Dental (Inferior alveolar nerve) Neuroleptanalgesic anesthesia

Techniques	Airway management Anesthesia provision in the US Arterial catheter Bronchoscopy Capnography Dogliotti's principle Drug-induced amnesia Intraoperative neurophysiological monitoring Nerve block Penthrox inhaler Tracheal intubation

Scientific Principles	Blood–gas partition coefficient Concentration effect Fink effect Minimum alveolar concentration Second gas effect

Measurements	ASA physical status classification system Baricity Bispectral index Direct Fick method Entropy monitoring Fick principle Goldman index Guedel's classification Mallampati score Neuromuscular monitoring Thyromental distance

Instruments	Anaesthetic machine Anesthesia cart Boyle's machine Gas cylinder Laryngeal mask airway Laryngeal tube Medical monitor Odom's indicator Relative analgesia machine Vaporiser Double-lumen endotracheal tube Endobronchial blocker

Drugs	Benzodiazepine Etomidate General anaesthetic Inhalational anaesthetic Infiltration analgesia Ketamine Local anesthetic Methohexital Methoxyflurane Midazolam Neuraxial blockade Opiate Propofol Thiopental Thiopentone

Complications	Emergence delirium Allergic reactions Anesthesia awareness Local anesthetic toxicity Malignant hyperthermia Perioperative mortality Postanesthetic shivering Postoperative nausea and vomiting Postoperative residual curarization

Fields of study	Cardiothoracic Geriatric Oral sedation dentistry

Professions	Anesthesiologist Anesthesiologist assistant Nurse anesthetist Operating Department Practitioners Certified Anesthesia Technician Certified Anesthesia Technologist Anaesthetic technician

History	A.C.E. mixture Helsinki Declaration for Patient Safety in Anaesthesiology History of general anesthesia History of neuraxial anesthesia History of tracheal intubation

Organizations	American Association of Nurse Anesthetists American Society of Anesthesia Technologists & Technicians American Society of Anesthesiologists Anaesthesia Trauma and Critical Care Association of Anaesthetists of Great Britain and Ireland Association of Veterinary Anaesthetists Australian and New Zealand College of Anaesthetists Australian Society of Anaesthetists International Anesthesia Research Society

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