Manual Squeezing Research Articles

A novel polyurethane-based sorbent material for oil spills management

The performances of FoamFlex200 (TEST-1 SB S.r.l.), an innovative material based on flexible polyurethane foam, have been tested through laboratory and tank tests for the purpose of oil removal in case of oil spill and water treatment. The possibility of reusing this material after regeneration via manual squeezing or by means of a suitable equipment was also evaluated. By way of comparison, the same experimental tests were conducted using polypropylene (PP) flakes, the material currently most used to cope with spill accidents. To better understand the hydrophobic oleophilic properties of the new material, and its application performance, it was tested with oils having different chemical and physical properties, in particular kerosene, diesel, and crude oil. From the laboratory tests, the capacity of FoamFlex200 to retain oil was found to be directly proportional to the viscosity of the latter. Sorption values detected range from 23.2 ± 1.4 g/g for crude oil and 18.8 ± 1.2 g/g for diesel to 8.8 ± 0.6 g/g for kerosene, confirming the potential of the innovative material compared to the PP. Cyclical use/regeneration tests were also performed, showing a high reusability of the material (up to 200 times according to the manufacturer’s declaration), with only a slight sorbent capacity decrease in cycles after the first one. Finally, some considerations based on the sorption capacities found were drawn, suggesting the adoption of the new material as also economically preferable, with relevant savings per kg of hydrocarbon treated ranging from 20% to 40% up to a maximum of 94% in the limit of 200 uses. In addition to these savings, the possibility of recovering sorbed oils represents another important advantage, both in economic and environmental terms.

Super-hydrophobic graphene-coated thermoplastic polyurethane porous monolith with superior photothermal effect for solar-assisted efficient cleanup of crude oil spill

Frequent occurrences of oil spill accidents have posed a serious threat to ecological system and human health, hence it is imperative to explore new-typed absorbent materials to efficiently clean up high-viscosity crude oil in an environmentally-friendly way. Herein we reported a reduced graphene oxide-wrapped and fluoroalkylsilane-modified thermoplastic polyurethane porous monolith (abbr. F-rGO@TPU monolith) with superior photothermal effect for solar-driven high-efficiency cleanup of crude oil spill. Owing to superior superhydrophobicity (water contact angle of 153°) and porosity (87.4 %), the as-prepared F-rGO@TPU monolith possessed high saturated absorption capacity (6.5–53.7 g/g) and splendid oil/water separation efficiency (over 99.3 %) for various low-viscosity oils/organic solvents. Excellent reversible compressibility and fatigue resistance (1000 compression cycles under 80 % strain) allowed the monolith to repetitively absorb oil via simple manual squeezing. By virtue of the outstanding photothermal effect of reduced graphene oxide coating, the F-rGO@TPU monolith exhibited almost full absorption (96.0 %) of solar spectrum (wavelength range of 250–2500 nm) and efficient light-to-heat conversion capability (achieving 80 °C in 5 min under 1.0 kW/m2 solar irradiation), enabling it to in situ reduce the viscosity of crude oil for rapid absorption. More importantly, the solar-heated monolith could continuously and fast separate crude oil/water mixture by a pump-assisted absorption device (crude oil flux of 510 kg/(m2·h)), revealing immense potential in oil spill remediation.

Natural silk fibers incorporated aramid nanofibers sponges for efficient oil/water separation

Industries and daily life produce large amounts of oily wastewater. For the efficient and economical separation of oil and water mixtures, silk microfibers (SM) were integrated with aramid nanofibers (ANF) to fabricate a hydrophobic and oleophilic O-SM/ANF sponge through a facile HCl volatilization method followed by hydrophobic surface modification. The O-SM/ANF sponges showed low density of 0.04–0.13 g/cm3, water contact angle of 130–138°, high absorption capacities up to 11.4–20.7 times of their own weight, and can be recycled for > 20 times by manual squeezing. The O-SM/ANF sponges exhibited high separation efficiencies for both immiscible oil/water mixtures and oil/water emulsions, desirable as oil/water separation materials.

Flexible and robust porous thermoplastic polyurethane/reduced graphene oxide monolith with special wettability for continuous oil/water separation in harsh environment

With the increase of severe environmental problems caused by oil spill and chemical leakage, there is an urgent necessity for efficient and durable oil/water separation materials with high environmental suitability. Here we developed a hierarchical porous superelastic thermoplastic polyurethane/reduced graphene oxide (TPU/RGO) monolith with superhydrophobicity/superoleophilicity for the continuous absorption of oils or organic solvents. The morphology investigation indicated that the three-dimensional porous structure of composite monoliths was definitely perfected by adding 1.5 wt% RGO, significantly improving hydrophobicity (155°) and mechanical property (compression strength of 307 kPa). In consequence, the TPU/RGO monolith could efficiently absorb different oils/organic solvents with high saturation absorption capacity (6.5–44.5 g g−1) and fast absorption speed (attaining equilibration within 15 s). And it possessed stable superhydrophobicity and absorption capacity in various pH (1–14), high/low temperature (0–90 °C) and strongly turbulent conditions. Furthermore, the composite monolith exhibited outstanding reversible compressibility (80% strain) and fatigue resistance (1000 cycles), endowing it with superior reusability by simple manual squeezing. More importantly, the flexible and robust monolith was capable of continuously and efficiently separating at least 15,000 times its own weight of oils or organic solvents from water with a peristaltic pump, showing huge potential for the large-scale cleanup of oily wastewater.

Understanding the dual-task costs of walking: a StartReact study

The need to perform multiple tasks more or less simultaneously is a common occurrence during walking in daily life. Performing tasks simultaneously typically impacts task performance negatively. Hypothetically, such dual-task costs may be explained by a lowered state of preparation due to competition for attentional resources, or alternatively, by a ‘bottleneck’ in response initiation. Here, we investigated both hypotheses by comparing ‘StartReact’ effects during a manual squeezing task under single-task (when seated) and dual-task (when walking) conditions. StartReact is the acceleration of reaction times by a startling stimulation (a startling acoustic stimulus was applied in 25% of trials), attributed to the startling stimulus directly releasing a pre-prepared movement. If dual-task costs are due to a lowered state of preparation, we expected trials both with and without an accompanying startling stimulus to be delayed compared to the single-task condition, whereas we expected only trials without a startling stimulus to be delayed if a bottleneck in response initiation would underlie dual-task costs. Reaction times of the manual squeezing task in the flexor digitorum superficialis and extensor carpi radialis muscle were significantly delayed (approx. 20 ms) when walking compared to the seated position. A startling acoustic stimulus significantly decreased reaction times of the squeezing task (approx. 60 ms) both when walking and sitting. Dual-task costs during walking are, therefore, likely the result of lowered task preparation because of competition for attentional resources.

A new method to prepare oil adsorbent utilizing waste paper and its application for oil spill clean-ups

A cellulose-based oil adsorbent was developed utilizing the waste paper PS-16 (mixed kraft cuttings) via a simple modification process. Through mechanical treatment and spray with polyethylene wax and alkyl ketene dimer, it was found that the product was significantly more hydrophobic than the raw material, with a water contact angle of 125.6°. The capability of the product to absorb engine oil, kerosene, and xylene was studied and compared with other cellulose-based adsorbents. The adsorbent had an excellent performance with a high absorbing ability of 16 to 28 times its own weight. Up to 92.8% of the oil in the adsorbents could be easily recycled and collected by manual squeezing. The adsorbent could be reused over eight cycles, and the sorption capacity remained constant. Therefore, this adsorbent is expected to be a promising oil sorbent for potential applications like oil spill clean-ups.

INFLUENCE OF EXTRACTION PROCESS ON YIELD, TOTAL PHENOLIC CONTENT, AND ANTIOXIDANT PROPERTIES OF AVOCADO (PERSEA AMERICANA MILL.) OIL AND STABILITY ASSESSMENT

Objective: The present study evaluated the impact of drying and storage conditions on the quality of the avocado oil.
 Methods: The fresh avocado was obtained from local farmers of Chiang Mai province, Thailand. The avocado pulp was collected and blended. The blended samples were dried at different temperatures (60, 80, and 100°C) and the oil was extracted by manual or mechanical pressing. The avocado oil samples were stored in clear and amber glass bottles at various temperatures (4, 30, and 40°C) for 3 months. The organoleptic, Folin–Ciocalteu colorimetric, 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid assay, and titration methods were used to measure the physical changes (color, odor, and precipitation), total phenolic content (TPC), antioxidant activity, and acid value (AV) and peroxide values (PVs) of the samples, respectively.
 Results: The manual squeezing and mechanical pressing methods yielded about 1.17 and 24.91% of avocado oil from fresh, undried avocado flesh, and the pH of both samples was 5. The AV of manually squeezed and mechanically pressed oil samples was 2.91 and 2.88 mg KOH/g of oil, respectively. The PV of manually squeezed and mechanically pressed oil samples was 7.96 and 8.03 milliequivalent of oxygen per Kg of oil, respectively. The quality of the avocado oil dried at 60°C was high compared to other samples regarding TPC and antioxidant capacity. The storage of oil samples for 3 months at various temperatures and in different containers has not affected the quality significantly, except at 40°C.
 Conclusion: The study proposed that the drying process at more than 80°C interferes with the quality of the avocado oil, and the storage conditions have a greater impact on the stability of the avocado oil. The storage at a low temperature in the absence of light may extend the shelf life of the avocado oil.

Self-sufficient, low-cost microfluidic pumps utilising reinforced balloons.

Here, we introduce a simple method for increasing the inflation pressure of self-sufficient pressure pumps made of latex balloons. Our method involves reinforcing the latex balloon with elastane fibres to restrict the expansion of the balloon and increase its inflation pressure. This allowed us to increase the operational inflation pressure of a latex balloon from 2.5 to 25 kPa. Proof-of-concept experiments show the suitability of the reinforced balloon for inducing lateral forces and recirculating flows, which are employed for hydrodynamic capturing of large human monocytes. We also demonstrate the ability for the rapid exchange of solutions in repeated cycles upon manual squeezing of the reinforced balloons. We also show the suitability of the reinforced balloon for studying the mechanobiology of human aortic endothelial cells under various shear stress levels. The simplicity, portability, affordability, hyper-elasticity and scalability of the reinforced balloon pumps make them suitable for a wide range of microfluidic applications.

Does internal cardiac massage play a role in ROSC after prolonged CPR ? : Our experience in a tertiary care hospital

AbstractCardiopulmonary resuscitation (CPR) is a life-saving skill involving chest compressions & ventilation to pump oxygenated blood through the vital organs of the body. Among different techniques and devices for chest compression, no single method has been definitively shown to produce the best outcome and hence, direct comparisons between them are not possible. Internal cardiac massage is the manual squeezing of the heart through a surgical incision into the chest cavity, when the chest is already open for cardiac surgery. Unlike the usual cardiac arrest scenarios, internal cardiac massage is employed mostly in cardiothoracic surgical patients and will have more chance for survival and favorable neurologic outcomes across all durations of CPR. We describe two cases of return of spontaneous circulation (ROSC) after prolonged CPR with internal cardiac massage performed in hospital setting.

Calling by Domestic Piglets during Simulated Crushing and Isolation: A Signal of Need?

This study examined whether piglet distress vocalizations vary with age, body weight and health status, according to the predictions of the honest signalling of need evolutionary model. Vocalizations were recorded during manual squeezing (a simulation of being crushed by mother sow) and during isolation on Days 1 and 7 after birth in piglets from 15 litters. We predicted that during squeezing, younger, lighter and sick piglets would call more intensely because they are in higher risk of dying during crushing and therefore they benefit more from the sow’s reaction to intensive vocalization. For isolation, we predicted that lighter and younger piglets would call more because they are more vulnerable to adverse effects of the separation. Calls were analyzed in their time and frequency domain. The rate of calling, call duration, proportion of high-pitched calls and eight acoustic parameters characterizing frequency distribution and tonality were used as indicators of acoustic signalling intensity. Piglets that experienced “squeezing” on Day 1 produced more intense acoustic distress signalling than on Day 7. Lighter piglets called more during squeezing than heavier piglets. Health status did not significantly affect any of the indicators of intensity of vocalization during squeezing. In isolation, none of the parameters of vocalization intensity were affected either by the age or by the weight of the piglets. In summary, the model of honest signalling of need was confirmed in the squeezed situation, but not in the isolation situation.

Manual squeezing as an alternative to mechanical stomaching in preparing beef carcass sponge samples for microbiological analysis.

The U.S. Department of Agriculture (USDA) requires beef abattoir operators to periodically analyze beef carcass sponge samples for levels of Escherichia coli. Additional beef carcass sponge sampling is commonly used by processors to evaluate the efficacy of beef abattoir antimicrobial intervention systems. The USDA sample preparation procedure requires that beef carcass sponge samples be mechanically stomached for 2 min before the sample fluid is squeezed out for analysis. When a large number of sponge samples must be analyzed, the stomaching step can limit throughput. In this study, we compared the USDA sample preparation procedure with repeatedly squeezing the sponge during a 10-s interval to expel the sample fluid. Separate sponge samples were obtained from each half of 100 chilled postintervention beef carcasses from a large-volume abattoir during a 4-month period. The USDA and squeezing treatments were randomly assigned to the halves of each carcass. All sponge samples were analyzed for E. coli, coliforms, Enterobacteriaceae, and aerobic mesophilic bacteria using Petrifilm methods. The sample preparation method had no significant effect (signed rank value > 0.05) on the results of any analytical test, although aerobic mesophilic bacteria counts tended to be higher after the USDA method than after manual squeezing alone. These results suggest that manual squeezing may be a simple and rapid alternative sample preparation method when gram-negative bacteria such as E. coli, coliforms, or Enterobacteriaceae are being enumerated from beef carcass sponge samples used to monitor operational abattoir hygiene.

Fatty Acid Profiles Associated with Microbial Colonization of Freshly Ingested Grass and Rumen Biohydrogenation

Two in situ studies were conducted to examine the use of odd-chain fatty acid profiles to study microbial colonization of freshly ingested herbage in the rumen as well as fatty acid biohydrogenation. In the first study, fresh perennial ryegrass was subjected to a range of sample preparation methods before incubation in the rumen for 2 or 7h. In the second study, fresh perennial ryegrass was chopped into 1-cm lengths and incubated in polyester bags in the rumen for 2, 8, and 24h. After removal of bags from the rumen, 4 different washing methods, ranging from manual squeezing to machine washing, were applied. Fatty acids were extracted from washed residues and determined, as methyl esters, by gas chromatography. The main odd-chain fatty acids (with the exception of anteiso C15:0) were not found in fresh grass and were useful markers of the effects of incubation time, sample preparation method, and washing method on microbial colonization/contamination. The concentration of these and other odd-chain fatty acids increased with incubation time in both studies. The results indicate rapid and continued microbial colonization of freshly ingested forages, although patterns of odd-chain fatty acids did not reveal any further information about the types of bacteria-colonizing herbage. Principal component, biplot analysis provided a useful overall description of the processes of microbial colonization and degradation of plant fatty acids on fresh herbage incubated in the rumen. Bolus formation during mastication and ingestion results in extensive damage to herbage; none of the techniques (cutting, crushing, and drying/grinding) investigated in this work was able to replicate the effects of bolus formation in the animal. The study provided further evidence of loss of unfermented feed particles through polyester bag pores, especially when feeds are dried and ground. Biohydrogenation of the polyunsaturated fatty acids of fresh herbage was used principally by solid-associated bacteria to enable them to take up high levels of trans-11C18:1 and C18:0 fatty acids. Although trans-11C18:1 was strongly associated with bacterial markers (odd- and branched-chain fatty acids), its precursor (cis-9, trans-11C18:2) was not associated with bacterial variation, suggesting that its production in the rumen under these conditions was mainly extracellular.

Textural quality assessment for fresh fruits and vegetables.

Academically, quantitative measurement of texture is essential for the study of the chemical and physiological mechanisms of texture. Commercially, quantitative measurement of texture is essential to ensure the quality of produce at packout. The diversity of tissues involved, the variety of attributes required to fully describe textural properties, and the changes in these attributes as the product ripens and senesces contribute to the complexity of texture measurement. Texture is a human assessment of the structural elements of a food. It is generally accepted that texture relates primarily to mechanical properties, so instrumental measurements relate mainly to mechanical properties. Fruits and vegetables exhibit viscoelastic behavior under mechanical loading, which means that the force, distance, and time involved in loading determine the value of any measurement. Because of their viscoelastic character, every effort should be made to hold the speed of the test constant in manual texture measurements and the rate of loading should be specified and controlled in mechanized measurements. There are many types of mechanical loading: puncture, compression, shearing, torsion (twisting), extrusion, crushing, tension, bending, vibration, and impact. The most widely used texture measurement for fruits and vegetables, after manual squeezing of course, is the Magness-Taylor fruit firmness test, which measures the maximum force to puncture the product in a specified way. The Kramer shear or shear-compression test is widely used in the processed foods industry, but is less commonly used by horticulturists. Nondestructive methods are highly desired both for sorting and for postharvest research. Compression tests of excised tissue pieces are frequently used in research. Nondestructive testing using impact, vibrational behavior, light scattering, and optical methods are being investigated but none has been widely accepted to date. Multiple instrumental measurements may be necessary to adequately the diversity of textural attributes sensed by the human consumer.

Reorganization of the hand somatosensory cortex following perinatal unilateral brain injury.

Functional magnetic resonance imaging was used to map the hand somatosensory cortices of nine hemiparetic young adult patients with perinatal unilateral brain injury in the sensorimotor area and five normal subjects. Stimulation of the paretic hand by periodic manual squeezing produced activation in the contralateral hemisphere of three patients and in the ipsilateral hemisphere of three other patients. Paretic hand stimulation produced no activation in either hemisphere of the remaining three patients. Therefore, one-third of the patients demonstrated functional "plasticity" of the brain in the form of inter-hemispheric relocation of the hand somatosensory function. The volume and pattern of activation for both hands was altered for those patients that showed evidence of cortical reorganization to the opposite hemisphere. This differs from the hand motor system, which exhibited inter-hemispheric reorganization in a higher proportion of a related group of hemiparetic subjects.

Dissecting the Mechanisms of Postintubation Laryngeal Trauma. Paulsen et al. (page 659)

Impaired movement of the cricoarytenoid joint (CAJ) is thought to be responsible for postintubation hoarseness and immobility of the vocal ligament. In an attempt to simulate the laryngeal complications associated with endotracheal intubation, Paulsen et al. intubated and extubated 37 unfixed larynges obtained from cadavers of people aged 25–89 within 48 h of death. The group specifically attempted to simulate the force of an endotracheal tube impinging on the arytenoid cartilage during intubation to reproduce the clinical result of arytenoid subluxation.The research group conducted a series of intubation trials in the hand-held larynges. The first injury mechanism was tested in nine right arytenoids and nine left arytenoids by first introducing the endotracheal tube under view into the larynx until the tip of the left or right arytenoid was inside the lumen of the tube. The tube was then inserted with a jerky motion. A second injury mechanism was tested in another nine larynges by introducing the tube into the larynx under view until the cuff had passed the subglottic region. The cuff was filled with air, and the tube was then pulled back through the cords with a jerky motion. In the final nine larynges, the researchers manually attempted to subluxate the arytenoid joint by squeezing the CAJ and applying pressure in the anterior–inferior direction (right CAJ) and in the posterior–lateral direction (left CAJ).Interestingly, none of the attempts using intubation or manual squeezing was successful in producing persistent subluxation of the arytenoid cartilage. Histologic analysis did show injuries in the synovial folds of some CAJs as a result of intubation attempts. Several CAJs showed chondrocyte clusters near the joint surface or a roughening of the entire cartilaginous joint surface. In a healthy state, the strong posterior cricoarytenoid ligament prevents dislocation of the arytenoid cartilage. Therefore, intubation trauma is unlikely a result of subluxation per se , but is more likely a consequence of the formation of a hemarthros or fractures of the joint bodies, leading to fixation of the joint surfaces in an abnormal position.

Are percutaneous transgastric biopsies using 14-, 16- and 18-G Tru-Cut needles safe? An experimental study in the rabbit.

We evaluated perforation, peritonitis and bleeding after 14-, 16-, 18-G Tru-Cut needles were passed through the stomach in an animal model. Insertions were performed on seven anaesthetized rabbits with 18-, 16- and 14-G needles simulating the clinical technique. Diluted contrast medium with methylene blue (60 mL) was administered through a nasogastric tube after the biopsy. Computed tomography (CT) scanning of the upper abdomen was performed 10 min after the insertion for leakage. The abdominal contents were inspected by laparotomy. There was no contrast medium leakage outside the gastrointestinal tract on CT images. Neither methylene blue nor other stomach content leakage was identified by laparotomy, even with manual squeezing. A tiny spot of blood was observed on the serosal surface of the stomach with the 18-G needle passes (five cases), whereas a relatively large haematoma was present with 14-G needle (four cases). Six of the rabbits survived and one died due to an inadvertant aortic injury. The results of the study show that transgastric route with an 18-G cutting needle can be used without fear of peritonitis and bleeding.

First attempt of interspecific hybridization between the shrimps Penaeus kerathurus Forskal,1775 and Penaeus japonicus Bate,1888

This paper reports preliminary studies designed to evaluate hybridization through natural mating and artificial insemination between female Penaeus japonicus Bate, 1888 and male Penaeus kerathurus Forskäl, 1775. Although both species were able to mature in captivity, natural copulation was not achieved. Different techniques, including manual squeezing in the base of the fifth pair of pereiopods, electrical stimulation and dissection, were used for the artificial insemination experiments. However, only dissection gave spermatophores. Stained sperm showed no malformations and its viability was very high. Seven out of 10 inseminations (70%) produced eggs, but the development of embryos was abnormal. It is suggested that the high genetic distance between these species is responsible for these results.

Evaluation of the effects of autotransfusion of unprocessed blood on hemodynamics and oxygen transport in anesthetized pigs.

To examine the hemodynamic effects and the oxygen transport pattern of autotransfusion of unprocessed blood on hemodynamics and oxygen transportation. Prospective, observational study. Research laboratory of a university medical center. Six healthy, domestic pigs (20 - 33 kg). A left thoracotomy was performed and a 5-mm incision was created in the descending aorta, resulting in a controlled hemorrhage of 30 mL/kg (approximately 40% of blood volume) into the thoracic cavity over a 45-min time period. During that period, mean arterial pressure (MAP) was maintained slightly > 50 mm Hg, using intravenous lactated Ringers' solution. The blood sample was collected from the open thorax with compresses soaked in citric acid solution and then extracted by manual squeezing, filtered through several layers of gauzes, and stored in glass bottles. Repeat measurements were performed after hemorrhage, after retransfusion of the harvested blood, and thereafter every 15 mins up to 60 mins. The animals were supported for 2 more hrs and were observed for the following 48 hrs. All animals survived and were in good condition 48 hrs after the experimental hemorrhage. The circulatory and oxygen transport response at the end of hemorrhage and concomitant maintenance of blood pressure at > 50 mm Hg resulted in: significant reductions of cardiac index, MAP, and oxygen transport (DO2) (46%, 50%, and 64% reductions, respectively, p < .01, in an increase of heart rate (HR) (+21%, not significant), pulmonary vascular resistance index (+112%, p < .05), and oxygen extraction (+105%, p < .01), as well as in a nonsignificant decrease of systemic vascular resistance index (-8%). After autotransfusion, the basic hemodynamic variables, MAP and HR were corrected, remaining near baseline (not significant) afterward. Cardiac index and DO2 increased after autotransfusion, but remained below the baseline until the end of the study protocol (p < .05). A significant increase was noticed for pulmonary arterial pressure and pulmonary vascular resistance index immediately after autotransfusion (p < .01). These values were corrected in part after 15 to 30 mins, but remained higher throughout the observaton period compared with baseline (29.5% and 89.8%, respectively, p < .05). The recently introduced relationship between cardiac index and oxygen extraction has been proposed to avoid problems of mathematical coupling between oxygen consumption and DO2 measurements. This relationship followed a similar course in all experiments throughout each phase. A shift downward and to the right represented the endpoint of the hemorrhagic phase. After autotransfusion, a shift toward baseline was noticed. Prothrombin time and partial thromboplastin time remained unchanged after autotransfusion. Free hemoglobin concentrations increased immediately after autotransfusion (+33%, p < .05), but returned to baseline values 48 hrs later. Histologic examination showed no changes in the examined organs. Reinfusion of large amounts of unprocessed blood (up to 40% of blood volume), collected with compresses from a noncontaminated surgical field is a cheap method, which may be of potential benefit in trauma patients, when more sophisticated autotransfusion devices are lacking. In the present study, this method resulted in transient but significant hemodynamic changes in the pulmonary circulation. Impairment of oxygen transport was noticed after the end of hemorrhage, but this impairment cannot be attributed to the autotransfusion technique alone, but also to factors such as hemorrhagic shock, surgical trauma, etc.

A Comparison of Field Techniques Used to Pressure-Infuse Intravenous Fluids

AbstractApplication of pressure infusion bags may increase intravenous (IV) flow rates three-fold. Commercially available pressure infusers, manual squeezing of the IV fluid bag, inflating a blood pressure (BP) cuff around the bag, and kneeling on the bag have been used by prehospital personnel attempting to augment fluid infusion rates. To test the efficacy of each these methods, seven experienced paramedics were asked to employ each method in two trials using a 1-liter bag of saline though a 14-gauge, 5.7cm catheter and a standard administration set. Gravity flow from 80cm served as the control.Pressure infusers generated flow rates of 257±54 ml/min and 296±53 ml/min when inflated to 300 mmHg and maximum pressure respectively. This rate was 2–2.5 times that of gravity flow (123±2 ml/min) and significantly greater than those rates obtained by any other method (p&lt;.0005). Manually squeezing the bag also was significantly better than was gravity flow with flow rates of 184±46 ml/min and 173±40 ml/min achieved by each of two different squeezing methods (p&lt;.01). Neither blood pressure (BP) cuff application and inflation (135±28 ml/min) nor kneeling on the bag (125±36 ml/min) was better than gravity alone.These results indicate that pressure infusers should be used to the exclusion of other field methods of supplying infusion pressure. If pressure infusers are not available, manually squeezing the bag is the only alternative acceptable in the field.

Mechanisms of Urinary Continence: An Animal Model to Study Urethral Responses to Stress Conditions

Under conditions of stress, the urethral sphincteric mechanism has to compensate a passive bladder pressure rise induced by increase in intraabdominal pressure. To evaluate the various closure mechanisms contributing to urethral response to stress, we subjected a female dog model to the physiologic stress condition triggered by sneezing. Vesical, rectal and 4 urethral pressures during sneezing were recorded simultaneously under various experimental situations: in the intact animal, after transection of the bladder and urethra, and with the abdomen open. The effects of the Credé maneuver and of manual squeezing of the surgically exposed bladder were also recorded.The data obtained support the existence of a 2-component urethral closure mechanism under stress: the proximal closure mechanism of the smooth muscular, intrapelvic urethra is from passive transmission of abdominal pressure. It is apt to balance a passive increase in bladder pressure and thus maintain proximal closure pressure during stress. The distal closure pressure mechanism reflects active reflex contraction of the intrinsic external sphincter and pelvic floor muscles, which is capable of exceeding passive increase in bladder pressure and thus augments closure pressure during stress.