Which is most pungent: isoflurane, sevoflurane or desflurane?

We compared the pungency and tolerability of three inhaled anaesthetics in a randomized, double-blind study. Eighty-one unpremedicated patients (n=27, each group) inhaled 2 MAC of isoflurane (2.3%), desflurane (12%) or sevofl urane (4%) for 60 s from an anaesthetic breathing circuit via a mask. Two b linded observers recorded coughing, complaints of burning and irritation, a nd how long the inhalation was tolerated. One sevoflurane patient coughed, but completed the study period, whereas Ii isoflurane patients and 20 desfl urane patients coughed, objected verbally or removed the mask forcefully. A ll sevoflurane, 20 isoflurane and seven desflurane patients completed the s tudy period (average 60, 49 and 33 s, respectively, P<0.05). The irritabili ty grading was: desflurane > isoflurane > sevoflurane (P<0.05). Sevoflurane is the least irritating agent for inhaiation at 2 MAC concentration.