Cervical spine injuries in blunt trauma patients requiring emergent endotracheal intubation.

Airway management in the blunt trauma patient is complicated by the potential for causing or exacerbating an injury to the cervical cord if an unstable cervical fracture is present. The records of 987 blunt trauma patients who required emergent endotracheal intubation over a 5-year period were retrospectively reviewed to determine the incidence and type of cervical spine injury and the incidence of injury based on airway management. Sixty of the patients (6.1%) had a cervical fracture; 53 were potentially unstable injuries by radiographic criteria. Twenty patients had neurologic deficits prior to intubation. Twenty-six patients with unstable injuries were intubated orally, 25 nasally, and two by cricothyrotomy. One patient developed a neurologic deficit after nasotracheal intubation. Because of a possible selection bias in which severely injured patients were preferentially referred to this trauma center, the true incidence of cervical spine injuries may be lower than the 6.1% we found. The authors conclude that the incidence of serious cervical spine injury in a very severely injured population of blunt trauma patients is relatively low, and that commonly used methods of precautionary airway management rarely lead to neurologic deterioration.

Seasonal availability of nematode larvae on pastures grazed by cattle in New South Wales.

Trends in the numbers of infective menatode larvae on pasture plots contaminated by cattle at different seasons of the year were defined in 3 different climatic regions. The main nematodes were Ostertagia ostertagi, Trichostrongylus spp, Haemonchus spp and Cooperia spp. On the North Coast of New South Wales with a sub-tropical climate, the numbers of infective larvae of all 4 nematodes rose rapidly to peak levels soon after each seasonal period of contamination began, then fell quickly within a few months. On the Central Coast of New South Wales, the trends were similar to those on the North Coast, except that the larvae persisted on the pasture for a much longer time. On the Northern Tablelands of New South Wales, where temperatures were much colder than on the coast, larval development was slower and major peaks of larval availability did not occur until early spring. These different seasonal trends in each region were considered to be related to the climatic differences between the regions. On pastures which were contaminated continuously, larval numbers reached maximum levels in mid-winter on the Central Coast and in early spring on the Northern Tablelands. It was concluded that the majority of these larvae were derived from the contamination of pastures in autumn and winter. Subsequently in summer, a rapid dying out of larvae was observed in all the regions, probably due to the effect of hotter weather. The studies suggest that a reduction in the contamination of pasture with nematode eggs in autumn and winter could result in pastures carrying fewer larvae and thus form the basis of effective worm control programs for cattle.

Seasonal changes in the structure of nematode populations of cattle in New South Wales in relation to inhibited larval development.

Pasture plots in 3 climatic regions were contaminated with worm eggs of Ostertagia ostertagi, Trichostrongylus axei, Haemonchus spp and Cooperia spp in the autumn, winter and spring. Successive pairs of parasite-free calves were grazed on the plots for 7 to 10 days at 4-week intervals and then killed for worm counts 14 days after their removal from pasture. On the Northern Tablelands of New South Wales, irrespective of the season of pasture contamination, the degree of inhibition of O. ostertagi was low in winter and highest in spring. T. axei showed similar trends while Cooperia spp showed negligible inhibition. On the North Coast of New South Wales, inhibited larvae accounted for a very small proportion of the O. ostertagi burdens, while in comparison T. axei showed a much greater degree of inhibition. Larval inhibition of Haemonchus spp occurred in autumn and early winter after which it did not occur. There was negliglible inhibition in Cooperia spp. On the Central Coast of New South Wales, there was little inhibition of O. ostertagi and none in T. axei. For Haemonchus spp, inhibited larvae were found mainly in autumn and winter. The numbers of inhibited Cooperia larvae were also highest in autumn and winter and were associated with large worm burdens. The marked difference between the tablelands and coastal regions in the seasonal trends of inhibition of O. ostertagi was considered to be due to a difference in strains between the geographical regions. The possible effect of climatic factors on the inhibition-proneness of infective larvae on pasture is discussed for Ostertagia and other nematodes. The roles of host resistance and density-dependence are also discussed.