“…The causes of increased intra-alveolar pressure are numerous, but the commonest of diem are aspiration of the new bora and asthma (Thawley, 1974) especially in older asthmatic children who have a long history of the disease (Ozonoff, 1965). Other causes are measles (Amin et at, 1972), violent coughing (Hunsicker et al, 1977), whooping cough (McNicholl, 1960), endotracheal anaesthesia (Thawley, 1974), the use of high pressure ventilators (Hunsicker et al, 1977) and occasionally the Valsalva maneuver (Agarwal, 1979).…”