(From to inflate,) inflatio; and sometimes leucophlegmatia; is any flatulent tumour: but it means generally a soft tumour arising from air being admitted into the cellular membrane. In Hippocrates it signifies an inflation of the belly, and sometimes a tumour in general. When ruptures or tumours are of the flatulent kind, they are called p/iysocele. Dr. Cullen means by the word pneumatosis, which is his general name for this disease, the swelling formed by air, a flatus, or rarefied fluids. He places it in the class cachexia and order intumescentiae, and defines it, a tense, elastic tumour of the body, making, on pressure under the hand, a crackling noise. The species are, I. Pneumatosis spontanea, when it happens without manifest cause; 2. Pneumatosis traumatica, when from a wound in the thorax; 3. Pneumatosis venenata, when from the swallowing or external application of poison; 4. Pneumatosis hysterica, when accompanied with hysterics.

The most frequent cause of this disorder is the piercing of the plura by a sharp pointed instrument, or wounding the lungs by the pointed fragments of broken ribs; though it sometimes happens that an emphysema is produced by internal lacerations of the air vessels of the lungs, without any injury to the pleura. Putridity separates air both in vegetable and animal substances; and, consequently, emphysema is the consequence of mortifications, and sometimes attends putrid fevers. It more seldom happens from pointed instruments than might be expected, as the blood instantly stops the passage.

An emphysema is known by a soft puffy swelling: the skin appears glossy, the tumour gives way on pressure, but it instantly returns; a crackling is perceived on pressing the emphysematous tumour. When the lungs are wounded, a troublesome cough attends, and the matter expectorated is mixed with blood; sometimes air escapes from the lungs into the cavity of the pleura, and occasions great difficulty of breathing, anxiety, a sense of suffocation, stupor, a livid colour in the face, and, if relief is not speedily obtained, death. The air detained in any part of the cellular membrane may produce a mortification in it.

When these tumours occur in putrid disorders, fomentations may be applied, made with equal parts of sharp vinegar and rectified spirit of wine; but when a wound is the cause, if the breathing is quick and laborious, blood must be taken, and the operation repeated as often as this symptom renders it necessary. Punctures, or rather small incisions, may be made into the cellular membrane with a lancet, or in different parts of the body; the air will thus be evacuated, if gentle pressure is also made on the tumour: after its evacuation, a compress may be dipped in vinegar, and applied over the part where the wound is supposed to be, secured by a tight bandage; and the patient should be directed to lie on the injured side, to prevent a fresh afflux of air. Nitre, and pectoral emulsions, may be given to prevent internal suppuration. When the air is detained in the cavity of the breast, Mr. Hewson proposes to discharge it by a small opening made with a knife on the fore part of the chest, which, if on the right side, must be between the fifth and sixth ribs, because there the integuments are thin: but if on the left side, the opening must be betwixt the seventh and eighth, or betwixt the eighth and ninth ribs; the better to avoid wounding the pericardium. See Le Dran's Observations, N° 29; James's Medical Dictionary, art. Fractura; and London Medical Observations and Inquiries, vol. ii. p. 17, vol. iii. p. 2836, 372399; White's Surgery, p. 78.