No abstract

No abstract

SummaryWe studied 128 patients undergoing nasal intubation to see whether the nostril side used influenced peri-operative nasal complications. In the apparently normal nostril, there is no significant difference between either nostril in difficulty of intubation ( p . 0.8). Similarly, there is no significant difference in the incidence of bleeding at intubation ( p . 0.2), at extubation ( p . 0.5) and once the patient has returned to recovery ( p . 0.1). Postoperative nostril patency is also similar between groups ( p . 0.85). Standard teaching of nasal intubation recommends that, in the first instance, the right nostril should be used when patency appears equal on both sides of the nose [1]. This is because the tracheal tube is designed such that the flat side of the bevel is on the left side of the tip. However, there is no evidence that the risk of trauma to the nose, or difficulty with intubation, is any greater using the left nostril. Many case reports of potentially serious complications of nasal intubation have in fact involved the right nostril [2±4].Our study aimed to elucidate whether the left nostril was more difficult to intubate than the right and whether the complications, in terms of bleeding and postoperative nostril patency, were different between the two sides. MethodAfter approval from the Hospital Research Ethics Committee, we studied 128 patients who were undergoing elective dental surgery that required nasal intubation. Patients were ASA classification 1 or 2. They had no history of nasal disease, including epistaxis, no coagulation problems, and were not taking medication likely to increase bleeding. None of the group had hypertensive disease. Patients were not studied if there was apparent unilateral decrease in nostril patency, determined by breathing through each nostril individually.A standard anaesthetic technique was used. Premedication with diclofenac 100 mg rectally was given up to 30 min before surgery. Induction and maintenance of anaesthesia was performed using a combined propofol (500 mg)/alfentanil (2 mg) infusion, with atracurium 0.3 mg.kg 21 given to facilitate intubation. Ventilation throughout anaesthesia was provided using an oxygen/ nitrous oxide mixture.The nostril side for intubation was chosen randomly and no vasoconstrictor spray was used. Intubation was performed using a Portex`Ivory' cuffed nasotracheal tube lubricated with water-soluble jelly. A tube with an internal diameter of 6.5 mm was used for men and 6 mm for women. The tube was passed through either nostril with the slant of the bevel facing to the left. The ease of passing the tube through the nostril was noted. Once the tip of the tube had passed into the oropharynx, direct laryngoscopy was performed and the presence of blood in the pharynx was noted. This was classified as either (1) blood absent, (2) blood staining on the cuff only (mild bleeding) or (3) blood pooling on the posterior pharyngeal wall (severe bleeding). The tube was then passed into the trachea under direct vision, the cuff was inflated ...

No abstract

No abstract

Shear localisation, in the form of discontinuities in the velocity profile, can occur in simulated fluid, associated with a limit to the shear stress. By modifying the thermostat, the occurrence of the plateau in the shear stress can be suppressed, resulting in a linear unconstrained velocity profile. The shear rate dependence of the traction coefficient leads to a limiting value of the traction coefficient even when the shear stress is unbounded. Simulations thus give insight into the molecular basis of the limiting shear stress behaviour in lubricants. The shear-induced positional ordering known as the “string phase” is found to occur in our hard-sphere model when the shear stress is limited, and where shear localisation also occurs, the string phase is restricted to the shear localisation regions.

Firearms legislation in the UK stems from the Firearms Act 1968 with its definition of a firearm as a lethal barrelled weapon of any description. The Act allows certain exceptions to be held without licence, most notably air weapons although these are limited by The Firearms (Dangerous Air Weapons) Rules 1969 and related regulations to below 12ft lb (16.3J) for air rifles and below 6ft lb (8.1J) for air pistols. Despite this there are occasional fatalities, typically 1 or 2 each year in the UK, from legally owned air weapons. In the USA there are over 20,000 visits each year to emergency departments due to injuries from air weapons and paintball guns. Despite this, limited research appears to have been carried out into the safety of air weapons and the present study tries to address this. Fresh samples of animal tissue were obtained from an abattoir or butcher and were embedded in ballistic gelatin. Pig heart, lung, liver and shoulder were used. By firing pellets into gelatin alone and into the combination of the gelatin and animal tissue it was possible to compare gelatin as a model for these tissues. The depth of penetration was similar but the residual track appeared to remain more open in the animal tissue. Pellets penetrated completely through the organ, with total penetration of gelatin and organ being typically around 10-15cm. Samples of pig, cow and chicken skin were placed in contact with the gelatin or embedded in the gelatin to simulate the effect of skin on penetration into a body. Chicken skin had no effect, pig skin stopped the pellet and cow skin was perforated by the pellet. If cow skin was embedded in the gelatin there was little effect on the total amount of penetration, but cow skin on the front surface of the gelatin reduced penetration by about 30%. Computed tomography was used to examine the pellet track and to calculate the volume of damage produced. However, due to the similar densities of gelatin and organ a technique had to be developed to differentiate phases. A barium salt paste was applied to outer surfaces and iodine solution or barium nitrate solution containing red food colouring was injected into the pellet track to enhance the contrast of the track. The track through the gelatin tended to enclose itself whereas the track through the organ remained more open, presumably due to the inhomogeneity of the fibrous nature of the tissue. Pellets were also fired at construction materials (wood, plasterboard and brick) and computed tomography used to determine the volume of damage created. Pellets perforated single layers of wood and plasterboard and would embed in a second layer. However, if the two layers were in contact the pellet did not penetrate the first layer. An air rifle pellet could therefore perforate house construction materials, although the resultant kinetic energy would be low and further damage would be limited. Some of the possible physical parameters are discussed that might help predict the degree of damage caused, but from this study it is not possible to define a limi...

We report that a shear-induced transition to an ordered state occurs in simulations of condensed molecular systems and that positional ordering can persist after shearing has stopped. Moreover, we calculate that shear fluctuations suffi­cient to induce microscopic ordering can occur in equilibrium fluids. We conclude that microscopic ordering induced by shear fluctuations provides a mechanism for homogeneous nucleation of the phase transition from liquid to crystal in real molecular systems and may therefore be used as the basis of a computational technique for investigating the crystallization of molecular liquids.