{'fraction_non_alphanumeric': 0.012379642365887207, 'fraction_numerical': 0.0, 'mean_word_length': 5.558558558558558, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Air embolism during neurosurgery in the sitting position. Two case reports.

SUMMARY Two patients undergoing posterior fossa exploration in the sitting position for removal of foramen magnum meningiomata suffered circulatory arrest from air embolism. Both were successfully resuscitated. The mechanism of air embolism is discussed with a review of relevant literature. The disadvantages of spontaneous ventilation are emphasized and it is recommended that controlled positive-positive ventilation should be employed. The means of maintaining a safe venous pressure and other precautions to reduce the incidence of air embolism are discussed. The monitoring techniques available and the treatment of this accident are evaluated.