Second gas effect

During induction of general anesthesia when a large volume of nitrous oxide is taken up from alveoli into pulmonary capillary blood, the concentration of gases remaining in the alveoli is increased. This results in effects known as the "concentration effect" and the "second gas effect". These effects occur because of the contraction of alveolar volume associated with the uptake of the nitrous oxide. Previous explanations by Eger and Stoelting have appealed to an extra-inspired tidal volume due to a potential negative intrapulmonary pressure associated with the uptake of the nitrous oxide.

There are two extreme breathing patterns and that the extra-inspired tidal volume is an artificial construct associated with one of these patterns.^[1] Thus it is the volume change that actually causes the effects.

Stedman's medical dictionary

When a constant concentration of an anesthetic like halothane is inspired, the increase in alveolar concentration is accelerated by concomitant administration of nitrous oxide, because alveolar uptake of the latter creates a potential subatmospheric intrapulmonary pressure that leads to increased tracheal inflow.

References

↑ Korman, B.; Mapleson, W. W. (May 1997). "Concentration and second gas effects: can the accepted explanation be improved?". British Journal of Anaesthesia. 78 (5): 618–625. doi:10.1093/bja/78.5.618. PMID 9175984.

Mapleson, W. W.; Korman, B. (Dec 1998). "Concentration and second-gas effects in the water analogue". British Journal of Anaesthesia. 81 (6): 837–843. doi:10.1093/bja/81.6.837. PMID 10211005.
Errata British Journal of Anaesthesia 1997;79:268

Anesthesia (outline)

Types	General Sedation Twilight anesthesia Local Topical Intercostal nerve block Neuraxial blockade Spinal Epidural Dental Inferior alveolar nerve

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

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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Second gas effect

Stedman's medical dictionary

See also

References