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. Questions and Answers. The Internet Journal of Anesthesiology. 1998 Volume 3 Number 3.
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What is halothane hepatitis ?
What is the difference between VCV and PCV in the ventilation of a patient ?
The feeding tube is placed in the right mainstem bronchus.
Fulminant hepatic necrosis following halothane anesthesia (halothane hepatitis) occurs in one of 6,000 to 35,000 cases and is often fatal. Halothane hepatitis is probably caused by trifluoroacetyl-containing metabolites binding to protein and subsequently forming anti- trifluoroacetyl protein antibodies. During re-exposure of the patient with halothane these antibodies may mediate massive hepatic necrosis. Other agents such as enflurane, isoflurane and desflurane has been associated with immune based hepatitis. Because the metabolism of enflurane, isoflurane or desflurane is much less than the one of halothane, fulminant hepatic necrosis occurs to a much lesser extent. Sevoflurane does not form such proteins and does therefore not cause hepatic toxicity.
VCV = Volume Controlled Ventilation
PCV = Pressure Controlled Ventilation
VCV is a ventilation mode with a set tidal volume. Its the ventilation mode mostly used in the operating room. The tidal volume will be delivered independent of the pressure (up to the setting of the pressure relief valve). The danger of VCV is barotrauma in patients at risk (i.e. patients with ARDS or COPD).
PCV is a ventilation mode with a set maximal peak airway pressure. It might be used in patients with diseases such as ARDS or bronchopleural fistula. The danger of PCV is decreased minute ventilation during episodes of high airway pressures (asthma, obstruction of endotracheal tube,...).