Rethinking the tiered trauma team response: A case-series study in a regional trauma centre.

OBJECTIVE: To reduce perceived unnecessary resource use, we modified our tiered trauma response. If a patient was not physiologically compromised, surgical registrar attendance was not mandated. We investigated the effect of this change on missed injury, unplanned representation to ED, diagnostic imaging rates and staff satisfaction. METHODS: A retrospective case series study assessing the 3-month period before and after the intervention was conducted. Logistic regression analyses were used to examine the association between ordering of computerised tomography (CT) and ED length of stay (LOS), injury severity (ISS), age, surgical review and admission. A staff survey was conducted to investigate staff perceptions of the practice change. Free text data were analysed using inductive content analysis. RESULTS: There were 105 patients in the control and 166 in the intervention group and their mean (SD) ISS was the same (ISS [SD] = 4 [±4] [P = 0.608]). A higher proportion of the control group were admitted (56.3% vs 42.2% [P = 0.032]) and they had a shorter ED LOS (274 min [202-456] vs 326 min [225-560], P = 0.044). The rate of missed injury was unchanged. A surgical review resulted in a 26-fold increase in receipt of a whole-body CT scan (odds ratio = 26.89, 95% confidence interval = 3.31-218.17). Just over half of survey respondents felt the change was safe (54.4%), and more surgical (90%) than ED staff (69%) reported the change as positive. CONCLUSION: The removal of the surgical registrar from the initial trauma standby response did not result in any adverse events, reduced admissions, pathology and imaging, but resulted in an increased ED LOS and time to surgical review.

Providers' utilization and perceptions of warfarin dosing algorithms.

INTRODUCTION: Warfarin dosing algorithms have proven beneficial in increasing time within therapeutic range (TTR) and decreasing adverse events associated with out-of-range international normalized ratios (INRs). Despite widespread availability, providers' utilization and perceptions of warfarin algorithms in real-world practice are unclear. Identifying perceptions and barriers to algorithm use may help attempts to improve warfarin therapy management. METHODS: Anticoagulation providers' utilization and perceptions of warfarin dosing algorithms were assessed via a nationwide electronic survey. RESULTS: Of the 246 providers who completed the survey, 82% were pharmacists, and 69% had over five years' experience dosing warfarin. Warfarin dosing algorithms were deemed beneficial by 84% of respondents and 72% currently use a warfarin dosing algorithm in their practice at least occasionally. Pharmacists were least likely of anticoagulation providers to use algorithms, although this was not statistically significant (p = 0.12). Algorithm utilization also decreased as years of warfarin dosing experience increased, with the highest rate of usage noted in the first year of dosing warfarin. The most common reason providers gave for discontinuing algorithm use was that they no longer felt it was needed. In this study, clinic patient volume did not appear to be associated with algorithm utilization. CONCLUSION: Warfarin dosing algorithms are frequently used among anticoagulation providers, especially those new to dosing warfarin, but use is frequently not sustained over the long-term. Education on the continued benefits of warfarin dosing algorithms could increase long-term utilization, potentially improving patient outcomes.

Laparoscopic harvest of the gastro-omental free flap for reconstruction after total pharyngolaryngectomy: Operative technique.

Circumferential defects following salvage pharyngolaryngectomy present significant challenges in reconstructive surgery. The gastro-omental free flap has been shown to reduce the incidence of major fistula and catastrophic complications. The current technique for harvest of the flap requires laparotomy, which is potentially associated with significant post-operative complications. Laparoscopic harvest of the gastro-omental free flap can negate some of the risks associated with open surgery. We describe here the operative technique for laparoscopic gastro-omental free flap harvest for use in reconstruction following total pharyngolaryngectomy. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1696-1698, 2017.

Optimization of oar blade design for improved performance in rowing.

The aim of the present study was to find a more optimal blade design for rowing performance than the Big Blade, which has been shown to be less than optimal for propulsion. As well as the Big Blade, a flat Big Blade, a flat rectangular blade, and a rectangular blade with the same curvature and projected area as the Big Blade were tested in a water flume to determine their fluid dynamic characteristics at the full range of angles at which the oar blade might present itself to the water. Similarities were observed between the flat Big Blade and rectangular blades. However, the curved rectangular blade generated significantly more lift in the angle range 0-90 degrees than the curved Big Blade, although it was similar between 90 and 180 degrees. This difference was attributed to the shape of the upper and lower edges of the blade and their influence on the fluid flow around the blade. Although the influence of oar blade design on boat speed was not investigated here, the significant increases in fluid force coefficients for the curved rectangular blade suggest that this new oar blade design could elicit a practically significant improvement in rowing performance.

A mathematical model of the oar blade - water interaction in rowing.

Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion.

A fluid dynamic investigation of the Big Blade and Macon oar blade designs in rowing propulsion.

The purpose of this investigation was to examine the fluid dynamic characteristics of the two most commonly used oar blades: the Big Blade and the Macon. Scaled models of each blade, as well as a flat Big Blade, were tested in a water flume using a quasi-static method similar to that used in swimming and kayaking research. Measurement of the normal and tangential blade forces enabled lift and drag forces generated by the oar blades to be calculated over the full range of sweep angles observed during a rowing stroke. Lift and drag force coefficients were then calculated and compared between blades. The results showed that the Big Blade and Macon oar blades exhibited very similar characteristics. Hydraulic blade efficiency was not therefore found to be the reason for claims that the Big Blade could elicit a 2% improvement in performance over the Macon. The Big Blade was also shown to have similar characteristics to the flat plate when the angle of attack was below 90 degrees , despite significant increases in the lift coefficient when the angle of attack increased above 90 degrees . This result suggests that the Big Blade design may not be completely optimized over the whole stroke.

The influence of stretcher height on the mechanical effectiveness of rowing.

The aim of the present study was to determine the effect of varying the height of the foot stretcher on the mechanical effectiveness of rowing. Ten male university level rowers rowed maximally for 3 minutes 30 seconds on a modified Concept 2 rowing ergometer. Each participant completed one trial at three foot stretcher heights. Position 1 was the original Concept 2 stretcher position, with Position 2 being located 5 cm and Position 3 being 10 cm above the original position and in the same orientation. Pull force and velocity were measured, and mean power generated by the rowers was calculated for each stroke. It was shown that in all three stretcher positions, mean power per stroke decreased as a function of time during the trial, confirming the fatiguing effects of the task. Although mean power per stroke did not differ significantly between stretcher positions at the start of the trial, p = 0.082, a significant difference was observed between the original stretcher position and Positions 2 and 3 at the end of the trial, p < 0.05. The lowest decline in mean power occurred in the highest stretcher position. It is suggested that this improvement in effectiveness is due to a reduction in the active downward vertical forces applied to the foot stretchers which does not contribute to forward propulsion, and thus a reduction in energy waste during each stroke. It was hypothesized that further raising the stretchers will continue to lead to an improvement in effectiveness until the optimum stretcher height is reached, above which effectiveness will be reduced.

The role of osteogenic index, octahedral shear stress and dilatational stress in the ossification of a fracture callus.

The exact mechanism by which mechanical stimulus regulates the healing process of a bone fracture is not understood. This has led to the development of several hypotheses that predict the pattern of differentiation of tissue during healing that may arise from characteristic fields of stress or strain at the fracture. These have so far remained unproved because data on stress fields in actual fracture tissue have been unavailable until recently. Thus the present study examines the predictive performance of the hypothesis proposed in J Orthop Res 6 (1988) 736, against measured and calculated data reported in J Biomech 33 (2000) 415, using a 2D FEM of a clinical fracture. The hypothesis was used to predict the influence of stress fields present in the Gardner et al. tissues at four temporal stages during healing. These predictions were then correlated with callus-size, rate of endochondral ossification and ossification pattern subsequently observed by Gardner et al. in the clinical fracture. Results corroborate the hypothesis that high octahedral shear stresses may increase the size of the callus during the initial phase of healing, and they also suggest that this may be true during the later stages of the fracture fixation period. However, compressive dilatational stresses were not found to inhibit endochondral ossification, as suggested by the hypothesis. Although high shear stresses were found in regions indicative of fibrous tissue as postulated by the hypothesis, this was not found to be the case for high tensile dilatational stresses. Also, contour diagrams of Osteogenic index (I) indicated only limited correlation with callus maturation and the pattern of healing. Therefore, the hypothesis was not wholly successful in predicting healing pattern.

The biomechanical environment of a bone fracture and its influence upon the morphology of healing.

The mechanism by which mechanical stimulus of reparative tissues directs the pattern of healing of a bone fracture is not understood. Several hypotheses have been developed that predict the ossification pattern during healing for a given ambient mechanical environment. These have remained unproved because of the absence of data on stress fields in the reparative tissue of real fractures. The present study examines the predictive performance of the most recent hypothesis that was proposed by Claes and Heigele (J. Biomech. 32 (1999) 255), against measured and calculated data from the clinical fracture reported by Gardner et al. (J. Biomech. 33 (2000) 415). The hypothesis was used to predict ossification from the preceding stress and strain fields present in the FEM of Gardner et al. at four temporal stages during healing. Predictions were then compared with the observed differentiation and maturation. During early healing of the interfragmentary gap region, the hypothesis correctly predicted the formation of connective tissue and fibrocartilage, and during later healing it correctly predicted the beginning of endochondral ossification. At the periphery of the periosteal callus, the hypothesis correctly predicted intramembraneous ossification during early healing, and also its thickening by endochondral ossification during later healing. However, the hypothesis incorrectly predicted intramembraneous ossification during early healing of the main periosteal callus, although in later healing it correctly predicted endochondral ossification.

Modeling signal loss in surficial marine sediments containing occluded gas.

The presence of occluded gas in inland lakes, harbor muds, and surficial marine sediments is well documented. Surficial gassy sediments cause underlying beds to be acoustically impenetrable to seismic surveys; therefore, the modeling of signal loss arising from mudline reflection and transmission absorption is of particular interest. The Anderson and Hampton [J. Acoust. Soc. Am. 67, 1890-1903 (1980)] model for attenuation in gassy sediments was evaluated against the physical and acoustical properties of eight laboratory silty clay soils containing different amounts of occluded gas in bubbles of 0.2- to 1.8-mm diameter. The model was shown to give good agreement with measured data over the lower frequencies of bubble resonance and above resonance. It did not agree with measured data at frequencies below resonance, for which the model did not simulate the bulk properties of the gassy soils. The Mackenzie [J. Acoust. Soc. Am. 32, 221-231 (1960)] model for reflection loss was also examined for the gassy soils. The maximum reflection losses of 6 dB, at a grazing angle of 40 degrees, does not wholly support speculation by Levin [Geophysics 27, 35-47 (1962)] of highly reflective pressure-release boundaries arising from substantial reflection and absorption losses in gassy sediments. It was found that mudlines formed from sediments with significant occluded gas may be successfully penetrated, although the substantial absorption loss arising from signal transmission through the sediment prevents penetration of the surficial layers to much beyond a meter in depth.

Is the stability of a tibial fracture influenced by the type of unilateral external fixator?

OBJECTIVE: To examine whether the type of unilateral external fixator significantly influences the stability of a tibial fracture. DESIGN: Inter-fragmentary displacements were measured during walking while the fractures were stabilized, first with one type of fixator then with another. BACKGROUND: It is commonly claimed that one type of fixator exerts a different influence on mechanical stability at a fracture in comparison with another. METHODS: This study compares inter-fragmentary displacement, fixator displacement and weight bearing during walking, in four patients stabilized with an Orthofix DAF, which was replaced by a Howmedica International Monotube. RESULTS: The null hypothesis of no difference in fixator performance was unproved (P < 0.05) through insufficient data. Interpatient variability in inter-fragmentary displacement implies that anthropometry, gait and fracture type may influence fracture stability more than the type of fixator. CONCLUSIONS: Since weight-bearing and displacements were not substantially different, no basis was found for the claim that one fixator provides a mechanical environment substantially different to another. Sample size was not large enough to prove that a small but statistically significant difference exists. RELEVANCE: The influence on fracture stability of one type of unilateral fixator in comparison with another appears to be less than the influence of anthropometry, gait and the type of fracture.