Supply Tubing Research Articles

In Vitro Evaluation of a Nasal Interface Used to Improve Delivery From a Portable Oxygen Concentrator

Abstract Portable oxygen concentrators (POCs) are widely used to administer long-term oxygen therapy (LTOT) and employ pulsed delivery modes to conserve oxygen. Efficient pulsed delivery requires that POCs are triggered by patient inhalation. Triggering is known to fail for some patients during periods of quiet breathing, as occurs during sleep. This article describes a new nasal interface designed to improve triggering of pulsed oxygen delivery from POCs. In vitro experiments incorporating realistic nasal airway replicas and simulated breathing were conducted. The pressure monitored via oxygen supply tubing (the signal pressure) was measured over a range of constant inhalation flow rates with the nasal interface inserted into the nares of the nasal airway replicas, and then compared with signal pressures measured for standard and flared nasal cannulas. The triggering efficiency and fraction of inhaled oxygen (FiO2) were next evaluated for the nasal interface and cannulas used with a commercial POC during simulated tidal breathing through the replicas. Higher signal pressures were achieved for the nasal interface than for nasal cannulas at all flow rates studied. The nasal interface triggered pulsed delivery from the POC in cases where nasal cannulas had failed to do so. FiO2 was significantly higher for successful triggering cases than for failed triggering cases. The nasal interface improved triggering of pulsed oxygen delivery from a POC and presents a simple solution that could be used with commercially available POCs to reliably supply oxygen during periods of quiet breathing.

Electropermanent magnet-driven droplet size modulation for two-phase ferromicrofluidics

A new ferrofluidic droplet generator is demonstrated using an electropermanent magnet to change the viscosity of the ferrofluid oil phase in a flow-focusing junction, which enables control of the aqueous droplet size. Electropermanent magnets are capable of fast switching (< 100 $$\upmu$$ s) and have magnetic field strengths comparable to those of permanent magnets. When switched on, the magnetoviscous effect increases the viscosity of the ferrofluid, thus increasing the channel’s fluidic resistance, slowing the flow rate of the oil-based phase and changing the droplet diameter. We have demonstrated on-demand droplet size modulation as large as 44% at speeds fast enough to modulate the size of a single droplet in a stream. Due to compliance in the supply tubing and Polydimethylsiloxane (PDMS) microfluidic channels, the change in droplet size relaxes with a time scale of seconds. An application of droplet size modulation was demonstrated by integrating a passive size-based magnetic droplet sorting stage.

The Effect of Blockages in a PEM Electrolyzers Flow-Field on Performance and Temperature Distribution

The ever growing demand for renewable energies is currently focused primarily on wind and solar energy. The technologies that capture these renewable energies have developed greatly in the past few decades with an ever increasing installed capacity all around the world. This capacity is however limited by grid demand and intermittency of the source1. In order to fully utilize the installed capacity of sustainable and renewable energy harnessed in wind and solar farms the energy collected at off-peak hours needs to be stored. By coupling a water electrolyzer to the wind and solar power farms the normally unutilized wind and solar energy can then be stored as hydrogen2. Hydrogen has a distinct advantage over other storage methods such as batteries, compressed air or pumped water as it can be stored and then employed into a variety of applications. The stored hydrogen could be used to fuel transportation, process chemicals, produce fertilizers and regenerate electricity1. Hydrogen also shares the ability to be produced, stored and distributed locally or centralized making it a versatile solution that can be brought very quickly into real, already existing commercial markets1. The major hurdles facing PEM electrolysis before it can truly and competitively enter commercial markets, is the cost of production and the operational cost of the system. The production costs have been a major focus of research since 2010, and a 41% reduction in cost has been shown at the stack level alone in the past 5 years3. The reduction of operational costs and increase in life expectancy and performance of the stacks also plays a critical role in the overall cost of hydrogen production. Some external factors such as poor water supply quality, hot spots from areas of high contact resistance or uneven loading of the catalyst layer, or even blockages in the flow-fields may limit a PEM electrolysis systems lifetime as well as its performance. In this article the effect of a blockage, as well as multiple blockages in a parallel flow channel were investigated using a segmented cell capable of reading temperature and current distribution over the entire active area of the test cell. A blockage in the flow-field could arise in an electrolysis cell through a large variety of sources, broken pieces of sealing material, poor water quality, large particles from corroded supply tubing and errors made during assembly. This could cause increases in mass transport losses and increased degradation rates on the rest of the cell. The cells operating parameters were also varied to explore and determine how to mitigate the effects a flow blockage has on cell performance. Figure 1

Shear-induced demixing in polymeric membrane dopes

One of the critical challenges in producing hollow fiber membranes is controlling fiber microstructure. The dope solutions involved possess (by design) an inherent thermodynamic sensitivity to phase separation, and are therefore susceptible to shear-induced microstructural changes when they are subjected to the complicated flow conditions that accompany spinning. This study demonstrates that shear-induced demixing is relevant in polymeric membrane dopes, and that it can affect macrovoid formation. Furthermore, we find that surprisingly subtle changes in shear history can affect demixing. Our investigation consisted of a two-tier approach. First, we used shear-small-angle light scattering (shear-SALS) to observe the microstructural evolution in liquid dope solutions before, during, and after shear flow. By varying the speed at which samples were syringe-loaded into the rheometer, we found that the pattern (and hence, the microstructure) observed after demixing varied based on shear history. In the second set of experiments, dopes with varying shear histories were extruded into a non-solvent bath to form solid fibers. Despite the fact that the fibers were all extruded under identical conditions, scanning electron microscopy (SEM) showed that the number of macrovoids observed varied widely between fibers. A comparison of the shear-SALS and extrusion results showed that shear-demixing is strongly linked to macrovoid formation. Our findings suggest that low-shear, upstream flow conditions (e.g., in supply tubing) could be just as important for fiber microstructure as the high-shear flow within the actual spinneret.

Interaction of coal-derived synthesis gas impurities with solid oxide fuel cell metallic components

Oxidation-resistant alloys find use as interconnect materials, heat exchangers, and gas supply tubing in solid oxide fuel cell (SOFC) systems, especially when operated at temperatures below ∼800 °C. If fueled with synthesis gas derived from coal or biomass, such metallic components could be exposed to impurities contained in those fuel sources. In this study, coupons of ferritic stainless steels Crofer 22 APU and SS 441, austenitic nickel–chromium superalloy Inconel 600, and an alumina-forming high nickel alloy alumel were exposed to synthesis gas containing ≤2 ppm phosphorus, arsenic and antimony, and reaction products were tested. Crofer 22 APU coupons coated with a (Mn,Co) 3O 4 protective layer were also evaluated. Phosphorus was found to be the most reactive. On Crofer 22 APU, the (Mn,Cr) 3O 4 passivation layer reacted to form an Mn–P–O product, predicted to be manganese phosphate from thermochemical calculations, and Cr 2O 3. On SS 441, reaction of phosphorus with (Mn,Cr) 3O 4 led to the formation of manganese phosphate as well as an Fe–P product, predicted from thermochemical calculations to be Fe 3P. Minimal interactions with antimony or arsenic in synthesis gas were limited to Fe–Sb and Fe–As solid solution formation. Though not intended for use on the anode side, a (Mn,Co) 3O 4 spinel coating on Crofer 22 APU reacted with phosphorus in synthesis gas to produce products consistent with Mn 3(PO 4) 2 and Co 2P. A thin Cr 2O 3 passivation layer on Inconel 600 did not prevent the formation of nickel phosphides and arsenides and of iron phosphides and arsenides, though no reaction with Cr 2O 3 was apparent. On alumel, an Al 2O 3 passivation layer rich in Ni did not prevent the formation of nickel phosphides, arsenides, and antimonides, though no reaction with Al 2O 3 occurred. This work shows that unprotected metallic components of an SOFC stack and system can provide a sink for P, As and Sb impurities that may be present in fuel gases, and thus complicate experimental studies of impurity interactions with the anode.

Barotraumatisme par effet Venturi lors du test d’apnée d’un patient en état de mort encéphalique : faut-il changer les modalités d’application de ce test ?

The clinical diagnosis of brain death is based on three clinical criteria, one of them being the abolition of the spontaneous breathing shown by an apnoea testing [1,2]. During this manoeuvre, oxygen is administered by intratracheal way through oxygen supply tubing inserted into the endotracheal tube. Few cases of barotrauma with tension pneumothorax during this test have been described in the literature bringing to the loss of potential donor or grafts for transplantation. The authors report a new case of tension pneumothorax occurred during an apnoea testing despite the precautionary measures necessary to prevent such a catastrophic complication. In addition to the possible pathophysiologic explanation of the event advanced by the authors, it seems lawful to redefine the practical modalities of implementation of this test to avoid the loss of potential grafts.

A Starting Procedure of Supersonic Ejector to Minimize Primary Pressure Load

A N EJECTOR is a flow device in which the momentum of the primary flow is transferred to the secondary flow. The momentum transfer takes place as the primary flow is injected into the secondary flow that is stagnant or moving. Ejectors are classified as subsonic, transonic, and supersonic depending on the flow speed at the exit of the primary nozzle. Typically the flow channel of an ejector is axis symmetric. Depending on the configuration of the primary flow inlet, the ejectors are either a central injection type or an annular injection type. Primary flow is injected either annularly or centrally based on the nature of the secondary flow. Ejectors have many advantages over other devices in pumping fluids [1–9]. Although ejectors with central injection primary flow are widely used, annular injection of primary flow is indispensable to certain applications: pumping chemical lasers and high speed/high altitude test facilities. To pump a high power chemical laser, central injection of primary flow cannot be used, as the supply tubing of the primary flow is exposed in the stream of high temperature secondary flow [10]. For a test facility to simulate a high speed/high altitude environment, the central injection with protrusion of the primary supply into the secondary flow would cause significant loss in the momentum of the secondary flow. The starting behavior of a supersonic ejector with annular injection of primary flow is different from one with central injection [11,12]. In the present study, the starting behavior of a supersonic ejector with an annular injection of primary flow was investigated. To recover stagnation pressure, supersonic ejectors are generally equipped with a mixing tube downstream of the injection of the primary flow. A sequence of the starting operation of such a supersonic ejector with annular injection of primary flow is illustrated in Fig. 1. The plot begins at a point where both primary stagnation pressure and secondary static pressure are equal to ambient pressure. As the stagnation pressure of the primary flow injection increases, the secondary flow accelerates from a stagnant ambient state and its static pressure decreases as shown in region (1) of Fig. 1. In this region, the flow is supersonic only within the primary nozzle. The whole flowfield outside of the primary nozzle is still subsonic. As the primary pressure further increases, the shock wave moves out of the primary nozzle to form an oblique shock as in region (2) of Fig. 1. When the primary pressure increases beyond the starting point, the oblique shockwave is abruptly swallowed by themixing tube and the whole flowfield inside the ejector becomes supersonic; the ejector is started and the static pressure of the secondary flow drops abruptly in region (3). Once the ejector is started, the static pressure of the secondary flow is not sensitive to the variation of the stagnation pressure of the primary flow. The ejector maintains supersonic operation, even when the stagnation pressure of the primary flow decreases below the value at which the ejector started. The unstarting of the ejector occurswhen the stagnation pressure of the primaryflow is noticeably less than the starting pressure. The discrepancy between the starting and unstarting stagnation pressures of the primary flow is due to the hysteresis of the ejector operation. To take advantage of this hysteresis, the stagnation pressure of the primary flow is lowered to a value that is slightly higher than the unstarting pressure, once the ejector enters the supersonic operationmode [13,14]. In this way, the design requirement on the primary flow that drives the ejector can be reduced. In the present study, a new procedure to start a supersonic ejector is proposed to reduce the burden on the stagnation pressure of the primary flow further. The new starting procedure was tested and validated by varying the secondary inlet condition. It was discovered that a significantly less primary mass flow rate was required to start a supersonic ejector when the new starting procedure was used.

Percutaneous Transtracheal Ventilation: Resuscitation Bags Do Not Provide Adequate Ventilation

Percutaneous, transtracheal jet ventilation (PTJV) is an effective way to ventilate both adults and children. However, some authors suggest that a resuscitation bag can be utilized to ventilate through a cannula placed into the trachea. Percutaneous transtracheal ventilation (PTV) through a 14-gauge catheter is ineffective when attempted using a resuscitation bag. Eight insufflation methods were studied. A 14-gauge intravenous catheter was attached to an adult resuscitation bag, a pediatric resuscitation bag, wall-source (wall) oxygen, portable-tank oxygen with a regulator, and a jet ventilator (JV) at two flow rates. The resuscitation bags were connected to the 14-gauge catheter using a 7 mm adult endotracheal tube adaptor connected to a 3 cc syringe barrel. The wall and tank oxygen were connected to the 14-gauge catheter using a three-way stopcock. The wall oxygen was tested with the regulator set at 15 liters per minute (LPM) and with the regulator wide open. The tank was tested with the regulator set at 15 and 25 LPM. The JV was connected directly to the 14-gauge catheter using JV tubing supplied by the manufacturer. Flow was measured using an Ohmeda 5420 Volume Monitor. A total of 30 measurements were taken, each during four seconds of insufflation, and the results averaged (milliliters (ml) per second (sec)) for each device. Flow rates obtained using both resuscitation bags, tank oxygen, and regulated wall oxygen were extremely low (adult 215 +/- 20 ml/sec; pediatric 195 +/- 19 ml/sec; tank 358 +/- 13 ml/sec; wall at 15 l/min 346 +/- 20 ml/sec). Flow rates of 1,394 +/- 13 ml were obtained using wall oxygen with the regulator wide open. Using the JV with the regulator set at 50 pounds per square inch (psi), a flow rate of 1,759 +/- 40 was obtained. These were the only two methods that produced flow rates high enough to provide an adequate tidal volume to an adult. Resuscitation bags should not be used to ventilate adult patients through a 14-gauge, transtracheal catheter. Jet ventilation is needed when percutaneous transtracheal ventilation is attempted. If jet ventilation is attempted using oxygen supply tubing, it must be connected to an unregulated oxygen source of at least 50 psi.

Is the Tension Beneath a Tension Infiltrometer What We Think It Is?

The tension infiltrometer has become a standard tool for measuring near‐saturated soil hydraulic properties. The objective of this study was to examine the dynamics of the supply tension at the interface between the tension infiltrometer and the measured soil using a pressure transducer under different soil conditions and to raise some cautions needed for proper use of this standard device. Infiltration experiments were conducted on a tension table, a large sand column, and in two field soils of contrasting textures and structures to test the performance of the standard two‐piece infiltrometer. Results showed that during high flow rates (&gt;200 cm3 min−1) the tension at the infiltrometer–soil interface started to deviate by as much as 15 mm from the desired tension. However, during field experiments the high flow rates were not experienced, and thus no deviation was observed between the preset desired tension and the actual measured tension at the infiltrometer–soil interface. To alleviate the problem of tension deviation under high flow, the water supply tubing and fitting diameters of the standard infiltrometer were successfully increased to yield a higher flow rate (≈300–400 cm3 min−1) without elevated tensions.

Avoiding Topical Anesthesia-Induced Methemoglobinemia

We read the interesting case reports by Carrodeguas et al1 and Srikanth et al2, regarding topical anesthesia-induced methemoglobinemia after using 20% benzocaine spray. Quickly recognizing and treating topical anesthesia-induced methemoglobinemia is laudable, but perhaps a better clinical strategy would be to avoid local anesthetic toxicity in the first place, by limiting how much local anesthetic is given. Estimating how much local anesthetic has been administered by a commercial anesthetic spray can be difficult; i.e. the recommended dose for 20% benzocaine spray is two sprays lasting a total of 1 sec, and the duration of the sprays (and thus the dose given) can be difficult to estimate. We suggest using an alternate topical anesthetic technique, a nebulizer facemask, to quantify and limit how much local anesthetic is used, and avoid topical anesthesia-induced methemoglobinemia. A nebulizer facemask can be assembled with a disposable hand-held nebulizer (e.g. Micro Mist Nebulizer, Hudson RCI, Temecula, CA) and a disposable aerosol mask (e.g. Elongated SEE-THRU Aerosol Mask, Hudson RCI, Temecula, CA). The nebulizer, typically used for aerosolizing medications for pulmonary patients, is filled with 4% lidocaine (5 ml). If nasal intubation is anticipated, phenylephrine 100 mcg in 1 ml can be added. The total potential lidocaine dose in the nebulizer (e.g. 200 mg) is easily calculated, and is low enough, in adults, to allow additional supplementation while remaining below a potentially toxic total dose (5 mg/kg lidocaine). The nebulizer is connected to oxygen supply tubing and the disposable aerosol mask. The nebulizer facemask requires less patient cooperation than a handheld nebulizer with a mouthpiece. The patient, in an upright position, is asked to breathe the nebulized local anesthetic solution for at least 10 minutes before intubation or endoscopy. This technique could also be used to blunt the gag reflex for esophagogastroscopy. The facemask nebulizer technique has other advantages: the equipment needed is readily available in most hospitals, and the nasopharynx, oropharynx, and trachea may all become anesthetized. In spontaneously breathing patients, when the intubation technique involves slowly advancing the endotracheal tube through the patient's airway as tolerated (e.g. blind nasal intubation or some fiberoptic intubation techniques), the nebulizer face mask can be placed over the end of the endotracheal tube outside the patient, delivering nebulized local anesthetic directly to the end of the endotracheal tube inside the patient, right where local anesthesia is most desired.

Gas-inducible product gene expression in bioreactors

Inducible transgene expression technologies are of unmatched potential for biopharmaceutical manufacturing of unstable, growth-impairing and cytotoxic proteins as well as conditional metabolic engineering to improve desired cell phenotypes. Currently available transgene dosing modalities which rely on physical parameters or small-molecule drugs for transgene fine-tuning compromise downstream processing and/or are difficult to implement technologically. The recently designed gas-inducible acetaldehyde-inducible regulation (AIR) technology takes advantage of gaseous acetaldehyde to modulate product gene expression levels. At regulation effective concentrations gaseous acetaldehyde is physiologically inert and approved as food additive by the Federal Drug Administration (FDA). During standard bioreactor operation, gaseous acetaldehyde could simply be administered using standard/existing gas supply tubing and eventually eliminated by stripping with inducer-free air. We have determined key parameters controlling acetaldehyde transfer in three types of bioreactors and designed a mass balance-based model for optimal product gene expression fine-tuning using gaseous acetaldehyde. Operating a standard stirred-tank bioreactor set-up at 10 L scale we have validated AIR technology using CHO-K1-derived serum-free suspension cultures transgenic for gas-inducible production of human interferon- β (IFN- β ). Gaseous acetaldehyde-inducible IFN- β production management was fully reversible while maintaining cell viability at over 95% during the entire process. Compatible with standard bioreactor design and downstream processing procedures AIR-based technology will foster novel opportunities for pilot and large-scale manufacturing of difficult-to-produce protein pharmaceuticals.

Experimental and numerical studies of adenovirus delivery to outflow tissues of perfused human anterior segments.

To investigate the efficacy of two different methods of adenoviral transfer of genes to trabecular meshwork (TM) and Schlemm's canal (SC) cells in cultured human anterior segments, using both experimental and numerical analyses. Replication-deficient adenoviruses having coding sequence for beta-galactosidase (beta-gal) under the control of the cytomegalovirus promoter were used. Efficiency of gene transfer over time was verified by infecting cultured human TM cells and assaying for beta-gal activity. Next, ostensibly normal paired human eyes were prepared by standard techniques and perfused for 2 to 5 days to measure baseline facilities. Eyes were then infected by one of two methods: standard transcorneal puncture, or injection into a 1 mm diameter silastic segment of supply tubing immediately upstream of the perfusion dish. In both cases, the nominal total dose was 2 x 10(8) viral particles. Five days after viral injection, eyes were harvested and fixed, and wedges from each of four quadrants were examined histologically. Sections were assayed for beta-gal activity and/or stained with toluidine blue. In a parallel study, flow and viral transport within perfused anterior segments were numerically simulated for conditions that approximated those used experimentally. Eyes receiving viral particles by transcorneal injection showed variable levels of beta-gal activity and highly variable TM cellular morphology, ranging from excellent preservation to cellular lysis. Eyes receiving an equivalent viral dose via the supply tubing showed higher transfer efficiency, as judged by almost complete TM cell loss (indicative of viral toxicity) and intense extracellular beta-gal activity from the residual cytoplasm. At lower doses (1/3 to 1/1000 of that used in transcorneal injection) beta-gal activity was still present, while TM cell morphology was good at the lower viral doses. Computer modeling showed that the region beneath the cornea was nearly stagnant, and consequently virus introduced into this region by transcorneal injection was delivered very slowly to the TM. This caused the effective delivered viral dose to be low and sensitively dependent on the volume and shape of the transcorneally injected virus bolus. Injection of adenovirus into supply tubing led to consistent delivery of reporter gene and approximately 300-fold greater efficiency of gene transfer compared to the transcorneal injection method, and is therefore the preferred method for introducing viral particles into perfused anterior segments. These findings were consistent with computer modeling of flow and mass transport in perfused anterior segments. Although these quantitative results are specific to adenovirus, this general trend should hold for a wide range of perfused compounds.

Barotraumatisme lors du test d’apnée chez des patients en état de mort encéphalique

We describe three cases of tension pneumothorax occurring during apnea testing for the determination of brain death. Every case needed needle thoracostomy for emergency chest deflation and/or a chest tube to be inserted rapidly. Moreover, haemodynamic and oxygenation parameters were impaired in each of the patients after these pneumothorax. This was uneventful for the two first patients (organs harvesting was contra-indicated or not consented by the patient’s family), but might be responsible for damaging lungs in the third patient and consequently loosing the pulmonary graft. Limitation of oxygen insufflation up to 8 L·min –1 with a 12 F oxygen supply tubing inserted within 5 cm into the endotracheal tube should be recommended to avoid this iatrogenic complication.

Highly Purified Silane Gas for Advanced Silicon Semiconductor Devices

Highly purified gas is required for manufacturing silicon semiconductor devices (e.g., the formation of Si‐single crystal, poly‐Si, , and siliside thin films. We have newly established a technology for delicately measuring impurities in gas by using a modified atmospheric pressure ionization mass spectrometer equipped with a two‐compartment ion source, with a lower detection limit around 0.1 to 1 ppb. We have succeeded in establishing the quantitative analysis method for disiloxane in gas by developing a new technology for generating a standard gas. This is a perfect reaction between and in the reactor. Its lower detection limit is 1 ppb. This analysis technology clarified that and changed rapidly into molecules containing oxygen atoms in the cylinder or supply tubing system (i.e., disiloxane, trisiloxane, … and particles). Therefore, this result shows that the impurities in gas to be controlled are not but siloxane and particles. Based on this technology, we have completed development of technology for manufacturing high purity gas free from , siloxane, and particles. In addition, we have established a technology for delivering highly purified gas to the point of use. It is expected that enhanced wafer yield and higher quality thin film will be ensured in the silicon semiconductor device manufacturing process.

Monitoring of Ventilation on and off Cardiopulmonary Bypass

Monitoring of Ventilation on and off Cardiopulmonary Bypass

Effectiveness of Teflon and Sevin Sprays in Controlling Caterpillar Damage to Microsprinkler Supply Tubing

Larvae of Selenisa sueroides (Guenee) can cause failure of the supply tubing used on microsprinkler assemblies in Florida citrus groves. The S. sueroides caterpillars use the microsprinkler supply tubing as alternate hosts to native plant species with hollow stems. They bore holes in the tubing, enter the hollow interior, and pupate. This experiment was conducted to determine if Sevin or Teflon sprays were effective at preventing damage to microsprinkler assemblies from S. sueroides. Microsprinkler assemblies made from either polyethylene or vinyl were placed in a field of Aeschynomene americana (American jointvetch), a known host to S. sueroides. Prior to placement in the field, assemblies were left untreated or were subjected to sprays by either liquid Sevin or liquid Teflon. Assemblies with polyethylene tubing had a higher incidence of damage than those with vinyl tubing. Assemblies sprayed with Teflon had about 40% of the damage of the untreated assemblies. Sevin was an ineffective treatment.

Use of supplemental oxygen during bystander-initiated CPR

To evaluate the efficacy of three methods by which rescuers can breathe supplemental oxygen to increase their delivered oxygen concentration (FDO2) during single-rescuer, bystander-initiated CPR. Controlled, randomized, crossover study. Simulation in laboratory setting using a CPR manikin. Thirteen-volunteer convenience sample group. Volunteers trained only in basic life support performed ventilation only and full CPR on a CPR manikin using room air and each of three supplemental oxygen delivery methods: nasal cannula, oxygen supply tube, and demand valve. The volunteers received minimal instruction on how to use the supplemental oxygen delivery methods. Peak FDO2 and peak carbon dioxide concentration; American Heart Association-defined ventilation and CPR compression performance indices. The data were analyzed using Duncan's method of analysis of variance. The mean peak FDO2 during ventilation-only/full CPR for the baseline (room air ventilation) and each supplemental oxygen delivery method (at specified flow rate) was: baseline (room air), -17.96% +/- 0.56%/16.77% +/- 0.56%; nasal cannula (at 10 L/min), -31.77% +/- 3.06%/27.01% +/- 3.68%; oxygen supply tubing (at 15 L/min), -36.82% +/- 9.93%/30.41% +/- 4.88%; and demand valve, -78.17% +/- 9.10%/68.22% +/- 7.10%. CPR performance was not hampered by the use of the supplemental oxygen methods. The use of supplemental oxygen increases the rescuer's FDO2 during ventilation-only and full CPR without interfering with CPR performance.

An improved nasal prong apparatus for end-tidal carbon dioxide monitoring in awake, sedated patients

We describe and evaluate a new apparatus that monitors end-tidal carbon dioxide (PETCO2) and augments the inspired oxygen concentration in awake, sedated patients. The unit was evaluated for its effectiveness as an oxygenation device and its accuracy as a predictor of PaCO2 through the correlation of PaCO2 with PETCO2. Twenty cardiac surgical patients, physical status ASA 2-4, participated in this study. The PETCO2 monitoring device consisted of a dual-prong nasal oxygen cannula and a 14-gauge intravenous catheter that was inserted into one limb of the oxygen supply tubing and connected to a Datex gas analyzer (Datex Instrumentation Corp, Helsinki, Finland) to measure PETCO2. The cross-over passage between the prongs was intentionally blocked with the end of a wooden-core cotton swab. The oxygen flow rates were randomly varied (2, 4, and 6 L/min) every 5 minutes, and values for PETCO2 as well as arterial blood samples for analysis of PaCO2 and PaO2 were obtained at the end of each 5-minute period. The accuracy of the system was assessed by comparing the PaCO2-PETCO2 differences (bias) at each oxygen flow rate. The ratios of PETCO2 compared with PaCO2 were 0.98, 0.94, and 0.85, with correlation coefficients of r = 0.81, 0.85, and 0.63, respectively. The PaO2 values were 114, 154, and 183 mm Hg for the corresponding nasal oxygen flow rates of 2, 4, and 6 L/min, respectively. This study indicates that this modified nasal cannula provides supplemental oxygen adequately and yields a satisfactory reflection of the PaCO2 depending on the oxygen flow rate delivered.

Reclaiming Partially Clogged Trickle Emitters

ABSTRACT A trickle emitter system, which had become partially clogged after 2 years of operation even with extensive water filtration, was reclaimed suc-cessfully by treating the entire system with concentrated hypochlorite and acid solutions. Chemical cost per emitter was less than replacement cost for the emitter and supply tubing. Maintenance treatment with low levels of hypochlorite and acid prevented recurrence of emitter plugging.

Well Stimulation by Downhole Gas-Air Burner

Abstract A successful gas-air burner has been developed to stimulate production by downhole in the producing interval, and heat losses.In field trials production increased with burner rate, up to maximum rates tested, directionally in agreement with theory. Production increases of 8 to 46 BOPD were observed for burner heat-release rates from 55,000 to 120,000 Btu/hour in wells producing 12 to 17 degrees API crude, cutting 5 to 75 per cent brine. The highest production increase measured was in a 3,500 ft. well with 140F formation temperature.In the longest test to date, the burner operated 300 days, including 240 days at rates of 100,000 Btu/hour or above. The test was stopped to examine the burner, and inspection indicated operating life would be at least two years, adequate for commercial use. Burner design, auxiliary equipment, operating procedure and range of economic application are discussed. Introduction Use of wellbore heating to increase oil production has been practiced extensively the last 15 years using both continuous and batch methods. Batch methods vary from simply dumping a few barrels of hot crude down the well annulus to large volume injection of crude or fuel oil heated to high temperature and pumped down the tubing at high surface pressures. Continuous wellbore heating has been practiced with hot water- or oil- circulating heaters, and to a lesser extent with downhole electric heaters. According to a supply company estimate, there are 3,500 circulating heaters operating in California alone. Valuable as these stimulation methods are, there remains an extensive range of conditions outside their capabilities. Batch heating requires periodic repetition, and costs increase when large volume, high-temperature treatments are used. Hot water circulating heaters are excellent performers in shallow wells, but the wellbore temperature attainable at reasonable cost falls off rapidly with depth because of high heat losses to strata above the producing formation. Electric heaters work well in some areas, but cable problems and burnout from coking are frequent problems. Power losses increase with depth, and capacity of electric heaters usually is not above 70,000 Btu/hour.It was concluded that significant improvement in the economics of viscous crude production would result from a new, high performance downhole heating method. Preferably the new method would be capable of high heat-release rates at depths to at least 5,000 ft. in wells with typical casing programs. Capital and operating costs should be minimized, consistent with dependable performance and minimum operating attention. This paper reports results of successful field trials with downhole gas-air burners and briefly describes burner design, installation and operation. Field test results are reported for an early model capable of 50,000 Btu/hour and for a new design proven satisfactory up to 120,000 Btu/hour and possibly capable of higher heat-release rates. The early model demonstrated feasibility of downhole burner operation, economic production increases, and the need for higher continuous heating rates to obtain additional production stimulation. Gas-Air Burner System The gas-air burner system includes the donwnhole burner, surface equipment to supply a combustible mixture of gas with air at elevated pressure, and downhole tubing to deliver the gas-air mixture to the burner. The burner is ignited by a small electric glow plug powered by cable run through the burner gas-air supply tubing. Equipment installation is straightforward and operation is trouble-free as demonstrated by field tests. Gas-Air Burner The burner shown in Fig. 1 has a tapered combustion chamber, cast from a specially formulated ceramic in the upper portion of a 15 ft, 3 1/2 in. diameter steel tube. A thermocouple, electric resistance igniter and flame arrestors are mounted in a machined steel igniter block located above the combustion chamber. The thermocouple indicates a temperature rise when the burner is operating; the igniter is used only to start the burner flame. Flame arrestors prevent flame propagation from the combustion chamber into the upper section of the burner and gas-air supply string. Gas-air mixture enters the combustion chamber through inlet tubes from the igniter block. JPT P. 1297^