Anaesthesia/anaesthetic agents volatile

Using Volatile Anaesthetic Agents. Dr. P. Fenton, Update in Anaesthesia, Practical Procedures, Issue 5,1995, http //www.nda.ox.ac.uk/wfsa/html/u05/u05 007.htm... 

A clinically useful action of a2-agonists is their ability to reduce the requirements for other anaesthetic agents during anaesthesia. In control mice, non-sedative doses of dexmedetomidine reduced the concentrations of the volatile anaesthetic, halothane, to induce anaesthesia by 30% (Lakhlani et al. 1997). This anaesthetic-sparing effect of a2-agonists was completely abolished in a2A-D79N mice. 

LEVODOPA ANAESTHETICS -GENERAL-VOLATILE AGENTS Possible risk of arrhythmias Uncertain Monitor EGC and BP closely. Consider using intravenous agents for maintenance of anaesthesia... 

Desflurane has the lowest blood/gas partition coefficient of any inhaled anaesthetic agent and thus gives particularly rapid onset and offset of effect. As it undergoes negligible metabolism (0.03%), any release of free inorganic fluoride is minimised this characteristic favours its use for prolonged anaesthesia. Desflurane is extremely volatile and caimot be administered with conventional vaporisers. It has a very pimgent odour and causes airway irritation to an extent that limits its rate of induction of anaesthesia. 

Halothane has the highest blood/gas partition coefficient of the volatile anaesthetic agents and recovery from halothane anaesthesia is comparatively slow. It is pleasant to breathe and is second choice to sevoflurane for inhalational induction of anaesthesia. Halothane reduces cardiac output more than any of the other volatile anaesthetics. It sensitises the heart to the arrhythmic effects of catecholamines and hypercapnia arrhythmias are common, in particular atrioventricular dissociation, nodal rhythm and ventricular extrasystoles. Halothane can trigger malignant hyperthermia in those who are genetically predisposed (see p. 363). 

In fact, N2O is usually employed alone as an anaesthetic agent during some special localized dental procedures only. However, most frequently N2O is utilized with other volatile anaesthetics to cause a sufficient desirable depth of anaesthesia essentially required for various surgical procedures . 

Calcium channel blockers with vasodilator effects, such as nifedipine, nicardipine, and nimodipine, will potentiate the effect of vasodilator effects of, e.g. halothane or isoflurane, potentiating any hypotension. This is especially obvious in hypertensive patients and when combined with similarly acting agents, such as sodium nitroprusside or nitroglycerin. Similarly, they also enhance the tendency of volatile anaesthetics to reduce hypoxic pulmonary vasoconstriction, which might exacerbate ventilation/perfusion mismatching during anaesthesia. 

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