Fluoride anesthetic agents

Monitoring of some gases such as NO2 [186, 216] and combustion gases [217] and measurements in the mid-IR region with fluoride glasses for CO2 at 4.5 pm [201] or anesthetic agents [203]. 

Desflurane is less potent than the other fluorinated anesthetics having MAC values of 5.7 to 8.9% in animals (76,85), and 6% to 7.25% in surgical patients. The respiratory effects are similar to isoflurane. Heart rate is somewhat increased and blood pressure decreased with increasing concentrations. Cardiac output remains fairly stable. Desflurane does not sensitize the myocardium to epinephrine relative to isoflurane (86). EEG effects are similar to isoflurane and muscle relaxation is satisfactory (87). Desflurane is not metabolized to any significant extent (88,89) as levels of fluoride ion in the semm and urine are not increased even after prolonged exposure. Desflurane appears to offer advantages over sevoflurane and other inhaled anesthetics because of its limited solubiHty in blood and other tissues. It is the least metabolized of current agents. 

Methoxyflurane (Penthmne) is the most potent inhala-tional agent available, but its high solubility in tissues limits its use as an induction anesthetic. Its pharmacological properties are similar to those of halothane with some notable exceptions. For example, since methoxyflurane does not depress cardiovascular reflexes, its direct myocardial depressant effect is partially offset by reflex tachycardia, so arterial blood pressure is better maintained. Also, the oxidative metabolism of methoxyflurane results in the production of oxalic acid and fluoride concentrations that approach the threshold of causing renal tubular dysfunction. Concern for nephrotoxicity has greatly restricted the use of methoxyflurane. 

In the case of the newest agent, sevoflurane, induction of anesthesia is achieved rapidly and smoothly, and recovery is more rapid than most other inhaled anesthetics including isoflurane. However, sevoflurane is chemically unstable when exposed to carbon dioxide absorbents, degrading to an olefinic compound (fluoromethyl-2,2-difluoro-l-[trifluoromethyl]vinyl ether, compound A) that is potentially nephrotoxic. In addition, sevoflurane is metabolized by the liver to release fluoride ions, raising concerns about possible renal damage similar to that caused by methoxyflurane. Sevoflurane comes close to having the characteristics of an ideal gas anesthetic, but a relatively insoluble compound that has greater chemical stability could be a useful alternative in the future. 

Methoxyflurane This agent is the most potent inhalation anesthetic because of its high solubility in lipid. Prolonged administration of methoxyflurane [meth ox ee FLURE ane] is associated with the metabolic release of fluoride, which is toxic to the kidneys. Therefore, methoxyflurane is rarely used outside of obstetric practice. It finds use in child-birth because it does not relax the uterus when briefly inhaled. 

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