Effects of user experience and method in the inflation of endotracheal tube pilot balloon on cuff pressure

Context: Endotracheal tube cuff pressure (ETCP) is recommended to be maintained between 20.30 cmH2O limits. While insufficient inflation of ETC may cause aspirations, over.inflation of it may lead to damage in tracheal epithelium.Aims: We planned to investigate the effects of user experience and cuff pressure inflation method differences following endotracheal tube cuff pressure and complaints about it.Patients and Methods: Two hundred and fifty patients planned for general anaesthesia were included in this study. ETC was inflated by users with different experience according to leakage or pilot balloon palpation techniques. ETCPs were measured by manometer at three periods (5 and 60 minutes after endotracheal intubation, and before extubation). Complaints about it were recorded in post anaesthetic care unit and 24 hours postoperatively.Results: Though we found experience of user had significant effect on the ETCP regulations, we observed inflation methods did not have any effect. However we found ETCP was higher than normal range with experienced users. A correlation was observed between cuff pressure and anaesthesia duration with postoperative complaints.Conclusions: Our study concluded that the methods used do not have any significant advantage over one another. While ETC inflated at normal pressure increases as userfs experience increases, experience alone is not enough in adjusting ETCP. A manometer should be used in routine inflation of ETC instead of conventional methods. CP and anaesthesia duration have correlations with some postoperative complaints.Key words: Endotracheal tube cuff pressure, experience of user, inflation method

Simulations of nanoscale Ni/Al multilayer foils with intermediate Ni2Al3 growth

Nanoscale multilayers of binary metallic systems, such as nickel/aluminum, exhibit self-propagating exothermic reactions due to the high formation enthalpy of the intermetallic compounds. Most of the previous modelingapproaches on the reactions of this system rely on the use of mass diffusionwith a phenomenological derived diffusion coefficient representing single-phase (NiAl) growth, coupled with heat transport. We show that the reaction kinetics, temperatures, and thermal front width can be reproduced more satisfactorily with the sequential growth of Ni2Al3 followed by NiAl, utilizing independently obtained interdiffusivities. The computational domain was meshed with a dynamically generated bi-modal grid consisting of fine and coarse zones corresponding to rapid and slower reacting regions to improve computational efficiency. The PDEPE function in MATLAB was used as a basis for an alternating direction scheme. A modified parabolic growth law was employed to model intermetallic growth in the thickness direction. A multiphase enthalpy function was formulated to solve for temperatures after discrete phase growth and transformations at each time step. The results show that the Ni2Al3formation yields a preheating zone to facilitate the slower growth of NiAl. At bilayer thicknesses lower than 12 nm, the intermixing layer induces oscillating thermal fronts, sharply reducing the average velocities

The Impact Of Crystal Morphology On The Thermal Responses Of Ultrasonically-Excited Energetic Materials

The ability to detect explosive materials may be significantly enhanced with local increases in vapor pressure caused by an elevation of the materials\u27temperature. Recently, ultrasonic excitation has been shown to generate heat within plastic-bonded energetic materials. To investigate the impact of crystal morphology on this heating, samples of elastic binder are implanted with single ammonium perchlorate crystals of two distinct shape groups. Contact piezoelectric transducers are then used to excite the samples at ultrasonicfrequencies. The thermal responses of the crystals are recorded using infrared thermography, and the rate of heating is estimated. Surface temperature increases up to 15 °C are found to arise after 2 s of excitation, with much higher heating levels expected near the inclusions themselves as demonstrated by the chemical decomposition of some crystals under favorable excitation conditions. The rates of heat generation are compared to various crystal morphology features through 2D estimates of length scale, perimeter and irregularity. It is observed that crystals grown in the lab, featuring sharp geometric facets, exhibit a higher probability of significant heat generation than inclusions with more spherical shapes. However, no statistical link is found between the rates of heat generation and the crystal morphology in those samples that do generate significant heating, likely because variations in surface roughness cannot be entirely eliminated during experimentation. It is hoped that this study will lead to a better understanding of the nature of heat generation in energetic materialsfrom ultrasonic sources

Applications of Additive Manufacturing Techniques in Making Energetic Materials

Energetic materials are currently manufactured using methods such as casting, which can only produce certain geometries. Additive manufacturing enables more flexible fabrication and the potential for improved material consistency. Additive manufacturing has transformed many industries, but has only recently been applied to the manufacturing of energetic materials. This paper describes the development of two processes to apply additive manufacturing methods to energetic materials. Method one applies a fused deposition modelling approach (FDM). 5 µm aluminum powder and PVDF were mixed and made into filaments using a Filabot Original filament extruder. Energetic filaments were created composed of 90:10, 80:20, and 75:25 mixtures of PVDF:Al by mass. These filaments had reactive sections, but did not have consistent composition and could not sustain self-propagating reactions. The second method had the goal of mixing ammonium perchlorate (AP) into a curable polymer which solidifies under UV light. Powdered sugar was used in place of AP to simulate the viscosity while testing extrusion and printing capabilities. The powdered sugar and UV Cure mixture could be extruded using a syringe pump when the powdered sugar to UV Cure ratio was 3:1, but this mixture would not stick to the print bed. Both processes need refinement to produce functional energetic materials. This paper forms a foundation for further development of processes in which additive manufacturing can be safely used to produce energetic materials

Heat generation in an elastic binder system with embedded discrete energetic particles due to high-frequency, periodic mechanical excitation

High-frequency mechanical excitation can induce heating within energetic materials and may lead to advances in explosives detection and defeat. In order to examine the nature of this mechanically induced heating, samples of an elastic binder (Sylgard 184) were embedded with inert and energetic particles placed in a fixed spatial pattern and were subsequently excited with an ultrasonic transducer at discrete frequencies from 100 kHz to 20 MHz. The temperature and velocity responses of the sample surfaces suggest that heating due to frictional effects occurred near the particles at excitation frequencies near the transducer resonance of 215 kHz. An analytical solution involving a heat point source was used to estimate heating rates and temperatures at the particle locations in this frequency region. Heating located near the sample surface at frequencies near and above 1 MHz was attributed to viscoelastic effects related to the surface motion of the samples. At elevated excitation parameters near the transducer resonance frequency, embedded particles of ammonium perchlorate and cyclotetramethylene-tetranitramine were driven to chemical decomposition

Obturacyjny bezdech senny jako czynnik ryzyka rozwoju chorób układu sercowo-naczyniowego

Obturacyjny bezdech senny jest stosunkowo często występującym schorzeniem, które dotyka około 5-15% populacji. Zaburzenie to zazwyczaj ściśle wiąże się ze zwiększonym ryzykiem rozwoju chorób układu sercowo-naczyniowego. Diagnostyka obturacyjnego bezdechu sennego opiera się na badaniu polisomnograficznym, a jego nasilenie mierzy się za pomocą wskaźnika bezdechów i spłyceń oddychania. Większość działań niepożądanych wywoływanych przez obturacyjny bezdech senny w odniesieniu do układu sercowo-naczyniowego ma, w toku włączonego leczenia, charakter odwracalny. Oprócz terapii za pomocą wentylacji w trybie ciągle dodatniego ciśnienia w drogach oddechowych w celu kompleksowego leczenia obturacyjnego bezdechu sennego zaleca się również zmniejszenie masy ciała, unikanie leków o depresyjnym wpływie na centralny układ nerwowy, leczenie niedrożności jamy nosowej, a także spanie w pozycji bocznej. (Folia Cardiologica Excerpta 2008; 3: 74-78

The Influence of the effect of solute on the thermodynamic driving force on grain refinement of Al alloys

Grain refinement is known to be strongly affected by the solute in cast alloys. Addition of some solute can reduce grain size considerably while others have a limited effect. This is usually attributed to the constitutional supercooling which is quantified by the growth restriction factor, Q. However, one factor that has not been considered is whether different solutes have differing effects on the thermodynamic driving force for solidification. This paper reveals that addition of solute reduces the driving force for solidification for a given undercooling, and that for a particular Q value, it is reduced more substantially when adding eutectic-forming solutes than peritectic-forming elements. Therefore, compared with the eutectic-forming solutes, addition of peritectic-forming solutes into Al alloys not only possesses a higher initial nucleation rate resulted from the larger thermodynamic driving force for solidification, but also promotes nucleation within the constitutionally supercooled zone during growth. As subsequent nucleation can occur at smaller constitutional supercoolings for peritectic-forming elements, a smaller grain size is thus produced. The very small constitutional supercooling required to trigger subsequent nucleation in alloys containing Ti is considered as a major contributor to its extraordinary grain refining efficiency in cast Al alloys even without the deliberate addition of inoculants.The Australian Research Council (ARC DP10955737)