[The influence of methoxyflurane (penthrane) on surface activity of the lung (author's transl)]

Methoxyflurane, at the moment the most potent inhalation anaesthetic, was examined in respect of its surfactant irritating properties in the rabbit. After a five hour anaesthesia with this compound there was, compared with a control group of animals which underwent only mechanical ventilation with room air for the same period, a significant decline of the compliance quotient from 2.99 to 2.55, indicating a relevant impairment of alveolar lining surfactant. A concomitant fall of arterial PaO2 from 84.8 to 71.3 mm Hg showed the resulting deterioration of respiratory function. Postanaesthetic preparations of these lungs examined using the Wilhelmy balance exhibited a significant fall of the stability index from 1.73 to 1.25, though hysteresis remained unaffected. Lung histology showed interstitial edema and patchy atelectasis, features which are found also in the early stages of post-traumatic pulmonary insufficiency. On this basis we recommend that methoxyflurane is not used in patients with impaired surfactant activity as such is found after severe traumatisation, head injury or in special preexisting pulmonary diseases. If this anesthetic is given to healthy individuals, the ventilatory pattern should include periodic sighs and prophylactic PEEP.