Breathing tube failures

76 Section of breathing tube showing fioat assembiy. 

77 Original PMMA sight tube with regular wall (as shown by shadow). 

A tool was commissioned and the first prototypes in acrylic proved encouraging (Fig. 10.18), although many moulding defects were present, such 

18 Prototype moulded sight tube in acrylic showing severe weld lines and flow marks (in shadow). 

Most common thermoplastics exhibit shear thinning, which means that the melt viscosity drops substantially in the runners of the tool, and thus makes moulding to shape much easier (Fig. 10.19). Thus, LDPE and polystyrene 

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Esteban A, Alia I, Gordo F, et al. Extubation outcome after spontaneous breathing trials with T-tube or pressure support ventilation. The Spanish Lung Failure Collaborative Group. Am J Respir Crit Care Med 1997 156(2 pt 1) 459 5. 

Ferrer M, Valencia M, Nicolas JM, et al. Early noninvasive ventilation averts extubation failure in patients at risk a randomized trial. Am J Respir Crit Cate Med 2006 173 164-170. Ezingeard E, Diconne E, Guyomarch S, et al. Weaning fiom mechanical ventilation with pressure support in patients failing a T-tube trail of spontaneous breathing. Intensive Care Med 2006 32 165-169. 

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