Venturi System Research Articles

A novel solar-driven vacuum desalination unit: Simultaneously venturi-induced self-evaporation and self-condensation with fresh water cycle

Integrating solar energy in desalination processes offers a cost-effective and efficient solution. Moreover, reducing the saturated temperature of water vapor through pressure reduction can lower energy consumption and improve evaporation rates. This study investigates the performance of a novel venturi system integrated with an evacuated tube collector (ETC) that simultaneously conducts low-pressure evaporation and condensation. The research evaluates the system’s response to variations in flow rate and explores the potential for reducing freshwater pump activity to conserve energy. Increasing the flow rate led to a greater pressure differential across the venturi, causing a decrease in throat pressure. The system achieves its peak water production at a flow rate of 75 L per minute (LPM), yielding 9.02 kg/m2 with a system pressure of 0.297 bar. This production signifies a notable surge of 37.01 % compared to the recorded minimum flow rate. The cost analysis indicates that the cost of producing one kilogram of water per unit area is $0.045. The system achieved its maximum efficiency of 40.87 % by decreasing the water pump operation time to 1.5 h/day while following a cycling pattern of 5 min on-15 min off.

A comparison of venturi and peristaltic based phacoemulsification efficiency in routine femtosecond laser cataract surgery

OBJECTIVETo compare the efficiency of venturi and peristaltic pump phacoemulsification systems in patients undergoing routine laser cataract surgery. DESIGNSingle center, non-randomized clinical study. PARTICIPANTSThe study compared consecutive eyes with moderate nuclear sclerosis undergoing routine laser cataract surgery at the Outpatient Eye Center, Mercy Health System, Springfield, MO, USA. METHODSEach surgery utilized the same femtosecond laser settings. Surgeries were performed with either a venturi or peristaltic vacuum system by a single surgeon (WJS). The EFX, percent power, ultrasound time (UST), the total time that the phaco tip was in the eye (phaco tip in/out time, PIOT) and the surgery time (speculum in/out time) were recorded. Exclusions and intraoperative complications were also analyzed. RESULTS995 eyes were included in the study. The EFX in the venturi eyes (1.7±1.3; n=521) compared to peristaltic eyes (2.1±1.4; n=474) was lower (p <0.0001). Similarly, the UST in the eyes performed with the venturi system versus the peristaltic system was reduced (32.4±22.3 sec vs. 40.7± 25.7 sec; p <0.0001). The PIOT in the venturi group compared to the peristaltic group was less (71.1±31.1 sec vs. 79.1±36.1 sec; p = 0.0002). The case time (speculum in/out time) was lower for the venturi eyes (307.2±68.8 sec vs. 311.6±53.6 sec; p=0.268). CONCLUSIONIn eyes undergoing routine laser cataract surgery, use of the venturi pump system was more efficient compared to peristaltic pump system based on energy use and time, and there was no significant difference in complications.

Direct determination of lithium in brine samples using handheld LIBS without sample treatment: sample introduction by venturi system.

Splashing is the main problem for the direct analysis of aqueous samples using LIBS since it generates serious precision and accuracy issues. This study demonstrates the direct determination of Li content in brines for the control of industrial mining processes using a portable LIBS device based on the direct laser impact on the sample, without any sample treatment, through the design of a sample injection system based on the Venturi effect. Our results demonstrated that the utilization of the 653.3 nm hydrogen line as an internal standard reduces the model calibration fitting error from 0.440 root mean square error in a standard calibration curve to 0.123 on the internal standard curve. Conversely, the development of a Venturi effect-based injection device using compressed air converts the brine into a fine mist which decrease splashing, resulting in an up to 10-fold error reduction, all without the necessity of employing an internal standard. Our results, evaluated by comparing them to the ASTM D3561-11 standard method using flame atomic absorption spectrometry, indicate that it is feasible to determine the lithium content in brine samples with an error of under 20% and a detection limit of 13 mg kg-1.

Helmet continuous positive airway pressure for patients’ transport using a single oxygen cylinder: A bench study

BackgroundContinuous positive airway pressure (CPAP) is frequently used to treat patients with acute respiratory failure in out-of-hospital settings. Compared to a facemask, the helmet has many advantages for the patient but requires a minimum gas flow of 60 L/min to avoid CO2 rebreathing. The aim of the present bench study was to evaluate the performance of four Venturi devices, connected to a single oxygen cylinder, in delivering helmet-CPAP with clinically relevant gas flow, fraction of inspired oxygen (FiO2), and positive end-expiratory pressure (PEEP) values. MethodsThree double-inlet Venturi systems (EasyVent, Ventuplus, Compact-HAR) were connected to full 5-L oxygen cylinders using a double flowmeter, and their oxygen requirements to reach different setups (flow 60-80 L/min; FiO2 0.4-0.5-0.6, PEEP 7.5-10-12.5 cmH2O) were tested. The fourth Venturi system (O2-MAX) was directly attached to the tank, and the flow and FiO2 delivered at preset FiO2 0.3 and 0.6 were recorded. The runtime of the cylinder was assessed. ResultsEasyVent, Ventuplus, and O2-MAX were able to deliver helmet-CPAP with clinically useful setups when connected to a single oxygen cylinder, while Compact-HAR did not. The runtime of the cylinders ranged between 28 and 60 minutes according to the preset flow and FiO2. The delivered gas flow decreased slowly and linearly with the drop in cylinder pressure until its exhaustion. ConclusionsHelmet-CPAP might be provided using portable Venturi systems connected to an oxygen cylinder, but not all of them are able to deliver it. The use of a double flowmeter allows delivery of both high flow and high FiO2 when double-inlet Venturi systems are used. Due to the flow drop observed during the cylinder consumption, a flow >60 L/min should be set when helmet-CPAP is started. Considering the flow drop phenomenon, the estimated duration of the tank runtime can be used with a margin of safety when planning patient transport.

Preferred cataract surgery practices in Malaysia: a survey based study

BackgroundTo describe the preferred cataract surgery practices among Malaysian ophthalmologists and medical officers in comparison with the recommended practices.MethodsAn online questionnaire was sent out in April 2021, to Malaysian Ophthalmologists and medical officers who perform cataract surgeries. The questions were focused on the preferred cataract surgery practices of the participants. All data obtained were collected, tabulated and analysed.ResultsA total of 173 participants responded to the online questionnaire. 55% of the participants were within 31–40 years of age. 56.1% preferred peristaltic pump over venturi system. 91.3% of participants practised povidone iodine instillation to the conjunctival sac. With regards to the main wound incision, more than half of the surgeons (50.3%) preferred fixed superior incision and 72.3% of them preferred 2.75 mm microkeratome blade. Most of the participants (63%) were inclined towards C-Loop clear intraocular lens (IOL) with a single-handed push preloaded system. 78.6% of the surgeons routinely use carbachol in their cataract surgery.ConclusionsThis survey provides some insight into the current practices among Malaysian ophthalmologists. Most of the practices are in line with international guidelines for preventing postoperative endophthalmitis. This article could help trainees and ophthalmologists benchmark and observe the common cataract surgery practices among their seniors and peers in Malaysia.

Evaluation of Soil-N Distribution and Corn Yield in Fertigation Systems

In Korea, field crop yields are steadily declining due to drought though it can be managed through irrigation. To address this problem, irrigation technology using subsurface drip line (SDL) has only recently been developed and distributed in Korea. In this study, fertilizer was supplied through SDL while growing corn on the arable land where SDL were buried. SDL was installed and a venturi system was connected for fertilizer injection. Irrigation and fertigation were controlled by connecting to the control panel. During corn cultivation, soil moisture levels were maintained at 100% and above 100% of the field capacity by soil moisture sensor. Nitrogen amounts and distributions of nitrate contents were measured by distance from SDL. Corn growth and yield characteristics were also measured. As a result, the total amount of nitrogen by distance released from the SDL was uniform, When evaluating the distributions of nitrate contents in the soil released from the SDL, NO3 was spread first to the upper part of the soil (after 1 day). And, after 9 day NO3 was spread evenly over the upper part of the soil rather than leaking to the lower part. It was determined that nutrients could be stably supplied to crops. There was a tendency that weight and diameter of ear during the growth of corn were greater than those supplied with topsoil, and the corn yield was also increased. Subsurface drip fertigation system is expected to have a positive effect on agricultural automation for better agriculture production.Distributions of nitrate content in the soil released from the subsurface drip over time; red dot: location of subsurface drip line, unit of legend: nitrate concentration (mg kg-1) - Each color represents a certain range of values, nday: n day after fertigation.

Flow generators for helmet CPAP: Which to prefer? A bench study

ObjectiveTo assess the different effect of filters’ application during helmet-CPAP delivered with three different flow generators on the delivered fresh gas flow, FiO2, and the noise level inside and outside the helmet. MethodsIn a bench study, three flow generators (air-oxygen blender, turbine ventilator and Venturi system) were used to generate two different gas flows (60 L/min and 80 L/min), with a fixed FiO2 at 0.6, to perform a helmet-CPAP on a manikin. Three different fixed PEEP valves (7.5, 10, and 12.5 cmH2O) were applied at the expiratory port. Gas flow, FiO2 and noise were recorded for each Flow-generator/Flow/PEEP combination, first without filter interposition and then after positioning a heat and moister exchanger filter (HMEF) at the helmet inlet port. ResultsThe application of the HMEF lead to a significant difference in the flow variation among the three flow generators (p < 0.001). Compared to baseline, the highest flow reduction was observed with the VENTURI (−13.4 ± 1.2 %, p < 0.001), a slight increase with the BLENDER (1.2 ± 0.5 %, p < 0.001), whereas no difference was recorded with the TURBINE (0.1 ± 0.6 %, p = 0.12). After HMEF was interposed, a significant FiO2 variation was observed only with VENTURI (11.3 ± 1.8 %, p < 0.001). As for the noise, the TURBINE was the least noisy system, both with and without the filter interposition. ConclusionsFlow generators used to deliver helmet-CPAP have different characteristics and responses to HMEF interposition. Users should be aware of the effects on FiO2 and flow of the different devices in order to make a precise setup of the circuit.

Design and experimental evaluation of a Venturi and Venturi-Vortex microbubble aeration system

This work presents an experimental evaluation of a Venturi and Venturi-Vortex microbubble aeration system, taking as input variables the water-air flow ratio, water renewal time and area-volume ratio of the water tank. The aeration process response variables are defined in terms of oxygen transfer and aeration efficiency through the standard volumetric mass transfer coefficient (KLa20), standard oxygen transfer rate (SOTR), and standard aeration efficiency (SAE). Two methods of air injection were analyzed: 1. Air injection in the throat chamber of the Venturi generator; 2. air supplying in the suction side of the hydraulic pump of the aeration system. Experimental results indicate that the water renewal time variable (RT) is a statistically significant factor with respect to the KLa20, which can be maximized by decreasing RT. The effects of the variable flow ratio (FR) are greater than the effects of renewal time and area-volume ratio (AVR) concerning SOTR and SAE, indicating a maximum response with a minimum flow ratio, using the Venturi-Vortex microbubble generator. When the flow ratio decreases, the air flow increases, generating and transferring a greater amount of microbubbles (MB) into the water. It was found that increasing the air flow produced an increase in the standard oxygen transfer rate SOTR and standard aeration efficiency SAE. Results allow concluding that the injection of the air flow from the suction side of the pump promotes the generation of microbubbles (MB) for a maximum air flow allowed by the system. SOTR and SAE could be maximized whit the flow ratio factor and the Venturi-Vortex generator, supplying air flow from the suction side of the hydraulic pump.

Venturi mask is the pioneer of High-Flow Oxygen Therapy Concepts

Oxygen therapy should be carefully considered and monitored because, as any other medications, it can cause harm to patients, if used inappropriately. This paper focus on the distinction between low-flow and high-flow oxygen therapy. A discussion about Venturi system for oxygen administration is carried on, given that some authors include it in the low-flow devices group despite its characteristics to deliver high flow therapy.

Configuration influence in relation to fluid flow of venturi system

AbstractDue to its simplicity and accurately measuring the flow rate, the venturi system is a special kind of pipe that is widely used in various applied fluid mixtures. One of the venturi system's important applications is ejectors devices that accurately facilitate adding air to water to sustain oxygen demand target levels in many waterworks engineering systems. This study aims to improve venturi system measurement accuracy through experimental investigation and analytical analysis for the venturi system conditional configuration parameters effect on target aeration operational efficiency. In the experiment work, different runs are implemented to characterize the performance of such aerators by describing the impact of venturi characteristics and configurations, including water flow rate, air inlets orifices diameters, inlet velocities, throat lengths, inlet angles, outlets angles, and outlet diameters on aeration efficiency. Results show that the venturi air vent diameter is an important governing parameter for determining aeration performance value. Additionally, an indicated increase in aeration performance with an increasing throat length to its diameter ratio. Meanwhile, the results revealed a varying noted effect of the venturi system characteristics and configurations on aeration performance. Moreover, the equations that relate venturi system configuration and Reynolds numbers with the aeration operational performance are developed to facilitate the target accurate aeration efficiency estimation.

The Effect of Filters on CPAP Delivery by Helmet.

When helmet CPAP is performed using a Venturi system, filters are frequently interposed in the respiratory circuit to reduce noise within the helmet. The effect of the interposition of these filters on delivered fresh gas flow and the resulting FIO2 is currently unknown. In a bench study, 2 different Venturi systems (WhisperFlow and Harol) were used to generate 3 different gas flow/FIO2 combinations (80 L/min-FIO2 0.6, 100 L/min-FIO2 0.5, 120 L/min-FIO2 0.4). Different combinations of filters were applied at the flow generator input line and/or at the helmet inlet port. Two types of filters were used for this purpose: a heat and moisture exchanger filter and an electrostatic filter. The setup without filters was used as baseline. Gas flow and FIO2 were measured for each setup. Compared to baseline, the interposition of filters reduced the gas flow between 1-13% (P < .001). The application of a filter at the Venturi system or at the helmet generated a comparable flow reduction (-3 ± 2% vs -4 ± 2%, P = .12), whereas a greater flow reduction (-7 ± 4%) was observed when filters were applied at both sites (P < .001). An increase in FIO2 up to 5% was observed with filters applied. A strong inverse linear relationship (P < .001) was observed between the resulting gas flow and FIO2 . The use of filters during helmet CPAP reduced the flow delivered to the helmet and, consequently, modified FIO2 . If filters are applied, an adequate gas flow should be administered to guarantee a constant CPAP during the entire respiratory cycle and avoid rebreathing. Moreover, it might be important to measure the effective FIO2 delivered to the patient to guarantee a precise assessment of oxygenation.

Finding Optimized Process Conditions to Minimize Precipitations in an SO2 Absorption Process Using Thermodynamic Process Simulation

A process model to describe SO2 absorption from exhaust gas using an absorptive magnesium-based slurry was developed in Aspen Plus® V10. The model includes the thermodynamic description of the electrolyte system MgO-CaO-SO2-H2O-O2-CO2, including precipitation reactions in the system. The property method electrolyte-NRTL with an asymmetric reference state was chosen as the thermodynamic method. The model was evaluated using plant data for pH value, HSO3- and SO3-- content of the liquid phase from an industrial SO2 absorption venturi system of the pulp and paper industry. The model shows good accuracy in describing the pH value and the combined HSO3- and SO3-- content. Sensitivity analyses were performed to identify key parameters that influence unwanted precipitation reactions in the system and to support the optimization of the SO2 absorption process. Temperature and the Mg(OH)2/SO2 ratio in the system were identified as key parameters influencing the formation and precipitation of sulfites. The pH value was identified as a key parameter affecting the precipitation of magnesium hydroxide. The model predicts the precipitation of Mg(OH)2 at a pH value of higher than 8 and the precipitation of MgSO3 trihydrate at a temperature higher than 78 °C or a slurry/SO2 ratio higher than around 4. The performed analyses can support optimized process design decisions for SO2 absorption processes to avoid limiting precipitation issues.

Effectiveness of Aerator Ventures, Deposition with Magnets, Filtering, and Ion Exchange in One Unit against Reduction of Iron, Total Dissolved Solid, and Marine Well Water

BACKGROUND: It is known the effectiveness of a venturi aerator, deposition with a sand filter magnet and ion exchange in one unit to reduce Fe content, total dissolved solid (TDS) and saltiness (CL content) in clean water, and the ability of ion exchange to reduce CL content is known. AIM: This study aims to analyze the effectiveness of venturi aerator, magnetic sedimentation, filtration, and ion exchange in one unit against Fe, TDS, and CL well water. METHODS: The method used is a quasi-experimental method using aeration with a venturi system, deposition with magnets, filtration, and ion exchange. The population in this study was all water containing Fe and CL in the Darul Kamal sub-district, Aceh Besar. The sample in this study is part of the population following research needs. RESULTS: The results showed an effect of a venturi aerator, deposition with magnets, filtering sea sand, anion, and cation resins in one unit to decrease Fe content and did not affect decreasing TDS content and Salinity. Moreover, a venturi aerator has an effect, deposition with magnets, filtering sea sand, anion, and cation resins in one unit on the decrease in Fe content, TDS, and salinity at deposition time of 24 h. Venturi aerator’s effect on Fe reduction does not affect TDS and CL of well water. There is an effect of venturi aerator and precipitation with magnets, in one unit on Fe reduction, and does not affect TDS and CL of well water. There is an effect of venturi aerator, precipitation with magnets, filtration in one unit on Fe reduction, no effect on TDS, and CL of well water. CONCLUSION: This tool effectively reduces Fe content and effectively reduces Fe, TDS, and salinity at a 24 h deposition time.

A novel Venturi system to generate high flow with titratable FiO2

Venturi-based flow generators are commonly used for noninvasive continuous positive airway pressure (CPAP) of high-flow nasal oxygen (HFNO). The system is simple and allows to increase the total flow while decreasing the FiO2 starting from a single oxygen source. In this report we describe the characteristics and performance of a novel Venturi system (EasyVEE, Levate, BG, Italy), which allows to vary the size of the port through which ambient air is entrained, hence allowing a continuous modulation of FiO2. The system allowed to modify FiO2 continuously between 35% and 80% and, consequently, a 1.5- to 4.5-fold increase of the total flow rate. A minimal decrease in entrainment performance was observed for positive end-expiratory pressure levels above 12.5 cmH2O. EasyVEE system appears to be a simple, flexible, and reliable solution to generate continuous flow for noninvasive respiratory support interfaces.

EFFECT OF GEOMETRIC CHARACHTARISTICS ON THE AERIATION EFFFICINCY IN THE VENTURI SYSTEM

Sufficient dissolved oxygen is required for helpful water quality. Natural stream cleansing procedures need enough oxygen levels for the purpose of supply for aerobic life systems. The happening of oxygen and water mixing together is titled aeration. There are several techniques to add air or oxygen to water, for instance open air reservoirs, submergible pumps, domestic aeration systems, compressor systems and air pump systems. However, the Venturi system, relied on the easiness of Ejectors, gives a easy, preservation free aeration solution. venturi system permits air to be injected inside running water from air inlet orifices and so rises oxygen levels in the water. The main objective of this research is to evaluate effect of geometric characteristics on the aeration efficiency in the venturi system. To achieve this goal, the venturi is designed and carried out, from transparent polycarbonate. Experiments were conducted under clear-water conditions at different discharges (Qwater): 44.16, 58.88, 73.59 and 88.31 lit/min which correspond to four inlet velocities (v): 1.5, 2.0, 2.5 and 3.0 m/s. The study involved selecting three different throat lengths (Lt): 12, 24 and 36 mm, and three different air inlets orifices diameters (ds): 3, 5 and 8 mm. Five different outlets angles have been used (β): 7o, 10o, 15o, 21o, and 25o with inlet angle (α) stabilization at 7o. The inlet and the outlet diameter (D) and throat diameter (dt) in all the experiments were constants and equals to 25 and 10 mm, respectively. The results of the study demonstrated that the geometric characteristics of the venturi system affects the aeration efficiency. Additionally, empirical equations were gotten for venturi tubes linking air flow and water flow to throat lengths and diameters, venturi outlets angles, air inlets orifices diameters and Reynolds numbers. إن وجود أکسجين مذاب کاف هو مطلب أساسى للحصول على جودة مياه مقبولة. حيث تحتاج إجراءات تطهير التيار الطبيعي إلى مستويات أکسجين کافية لغرض الإمداد بأنظمة الحياة الهوائية. ويسمى حدوث اختلاط الأکسجين والماء معا بالتهوية. وهناک العديد من التقنيات لإضافة الهواء أو الأکسجين إلى الماء ، منها على سبيل المثال: خزانات الهواء المفتوح والمضخات الغاطسة وأنظمة التهوية الداخلية وأنظمة الضواغط وأنظمة ضخ الهواء. ومع ذلک ، فإن نظام الفنشوري ، الذي يعتمد على سهولة استخدام الحاقنات، حيث يوفر حل تهوية سهل وغير معقد. حيث يسمح نظام الفينشوري بحقن الهواء داخل المياه الجارية من فتحات دخول الهواء وبالتالي يرفع مستويات الأکسجين في الماء. والهدف الرئيسي من هذا البحث هو تقييم تأثير الخصائص الهندسية على کفاءة التهوية في نظام الفنشوري. ولتحقيق هذا الهدف ، تم تصميم الفنشوري وتنفيذه من البولي کربونات الشفاف. أجريت التجارب تحت ظروف مياه نقية عند تصريفات مختلفة (Qwater) هى: 44.16, 58.88, 73.59 و 88.31 لتر / دقيقة والتي تتوافق مع أربع سرعات مدخل (v) هى: 1.5, 2.0, 2.5 و 3.0 م / ث. اشتملت الدراسة على اختيار ثلاثة أطوال مختلفة للقطاع المختنق (Lt) هى: 12, 24 و 36 مم ، وثلاثة أقطار مختلفة لفتحات دخول الهواء (ds) هى: 3, 5 و 8 مم. وتم استخدام خمس زوايا مختلفة للمخارج (β) هى : 7، 10، 15، 21 و 25 درجة مع تثبيت زاوية المدخل (α) عند 7 درجة. وکان قطر المدخل والمخرج (D) وقطر القطاع المختنق (dt) في جميع التجارب ثوابت ويساوي 25 و 10 ملم على التوالي. وقد أظهرت نتائج الدراسة أن الخصائص الهندسية لنظام الفنشوري تؤثر على کفاءة التهوية. بالإضافة إلى ذلک ، تم الحصول على معادلات تجريبية لأنابيب الفنشوري التي تربط تدفق الهواء وتدفق المياه بأطوال وأقطار القطاع المختنق وزوايا مخارج الفنشورى وأقطار فتحات دخول الهواء وأرقام رينولدز.

IMPACT OF VARYING THROAT DIAMETER IN THE VENTURI SYSTEM ON THE AERATION EFFICIENCY

Venturi tube is an applicable and economic alternative device to transfer gas-liquid. It is simply designed easily manufactured and it does not need maintenance. The process of air vacuum through venturi tube has been used widely in many agricultural, industrial and the process of water purification (e.g. chlorine and ozone injecting for drinking water, injecting chemicals as liquid fertilizers in the system of sprinkler irrigation/ transferring dissolved oxygen in drinking water and waste water treatment). The main objective of this research is to evaluate effect of geometric characteristics on the aeration efficiency in the venturi system. To achieve this goal, the venturi is designed and carried out, from transparent polycarbonate. Experiments were conducted on clear-water conditions at different discharges (Qwater): 44.16, 58.88, 73.59 and 88.31 lit/min which correspond to four inlet velocities (v): 1.5, 2.0, 2.5 and 3.0 m/s. The study involved selecting three different throat diameters (dt): 10, 12.50 and 15 mm, and three different air inlets orifices diameters (ds): 3, 5 and 8 mm. Five different outlets angles have been used (β): 7o, 10o, 15o, 21o, and 25o with inlet angle (α) stabilization at 7o. The inlet and the outlet diameter (D) and throat length (Lt) in all the experiments were constants and equals to 25 and 8 mm, respectively. The results of the study demonstrated that the throat diameter of the venturi tube affects the aeration efficiency.The best results were given for the relationship between (Qair / Qwater) = 92% with outlet angle of 25o in the case of (dt D = 0.4 and ds D = 0.32 and Lt D = 0.32). Additionally, empirical equations were gotten for venturi tubes linking air flow and water flow to throat lengths and diameters, venturi outlets angles. air inlets orifices diameters and Reynolds numbers. الفينشوري هو جهاز بديل اقتصادي قابل للتطبيق لنقل الغاز السائل. إنه مصمم ببساطة وسهل التصنيع ولا يحتاج إلى صيانة. تم استخدام عملية تفريغ الهواء من خلال أنبوب الفينشوري على نطاق واسع في العديد من العمليات الزراعية والصناعية وتنقية المياه (مثل حقن الکلور والأوزون لمياه الشرب ، وحقن المواد الکيميائية السائلة في نظام الري بالرش / ذیاره الأکسجين المذاب في المیاه - معالجة المياه ومياه الصرف الصحي). الهدف الرئيسي من هذا البحث هو تقييم تأثير الخصائص الهندسية على کفاءة التهوية في نظام الفينشوري. لتحقيق هذا الهدف ، تم تصميم الفينشوري وتنفيذه ، من مادة البولي کربونات الشفافة. أجريت التجارب تحت ظروف مياه نقیه عند تصرفات مختلفة (Qwater) :- 44.16 و 58.88 و 73.59 و 88.31 لتر / دقيقة والتي تتوافق مع أربع سرعات مدخل (v) :- 1.5 و 2.0 و 2.5 و 3.0 م / ث علی التوالی. وقد اشتملت الدراسة على اختيار ثلاثة أقطار مختلفة للحلق (dt) :-10 و 12.50 و 15 مم ، وثلاثة فتحات مداخل هواء مختلفة بأقطار (ds) :- 3 و 5 و 8 مم. تم استخدام خمس زوايا مختلفة للمخرج (β) :- 7o ، 10o ، 15o ، 21o ، و 25o مع استقرار زاوية المدخل (α) عند 7o وکان قطر المدخل والمخرج (D) وطول الحلق (Lt) في جميع التجارب ثابت ويساوي 8 و 25 مم على التوالي. وقد أظهرت نتائج الدراسة أن قطر الحلق لأنبوب الفينشوري يؤثر على کفاءة التهوية وقد ٲعطیت افضل النتائج للعلاقة بین Qair/Qwater)) = 92٪ مع زاویة خروج o25 فی حالة dt D) = 0.4 و ds D = 0.32 و Lt D = .(0.32 بالإضافة إلى ذلک ، تم الحصول على معادلات تجريبية لأنابيب الفينشوري التي تربط تدفق الهواء وتدفق المياه بأطوال وأقطار الحلق وزوايا مخرج الفينشوري وأقطار فتحات الهواء وأرقام رينولدز.

Noise Level and Comfort in Healthy Subjects Undergoing High-Flow Helmet Continuous Positive Airway Pressure.

The aim of this study was to assess the noisiness levels produced by different gas source systems, breathing circuits setup, and gas flow rates during continuous positive airway pressure (CPAP) delivered through helmet. This was a crossover design study. Ten healthy subjects received helmet CPAP at 5 cm H2O in random order with different gas flow rates (60 and 80 L/min), 3 diverse gas source systems (A: Venturi system, B: oxygen and air flowmeters, C: electronic Venturi system), and 3 different breathing circuit configurations. During every step of this study, a heat and moisture exchanger (HME) was placed on the helmet inlet gas port to measure the effects on noise production. Noise intensity level was recorded through a sound-level meter. Participants scored their noisiness perception on a visual analog scale. The noise level inside the helmet ranged between 76 ± 4 and 117 ± 1 Decibel A. The gas source and the gas flow rate always affected the noise level inside and outside the helmet (P < .001). The different "breathing circuit setup" did not change the noise levels inside the helmet (P = .244), but affected the noise level outside, especially when a Venturi system was used (P < .001). An HME filter placed at the junction between the inspiratory limb of the breathing circuit and the helmet significantly decreased the noise intensity inside the helmet (mean dBA without HME, 99.56 ± 13.30 vs 92.26 ± 10.72 with HME; P < .001) and outside (mean dBA without HME, 68.16 ± 12.05 vs 64.97 ± 12.17 with HME; P < .001). The perception of noise inside the helmet was lower when an HME filter was placed on the inspiratory inlet gas port (median, 6 [interquartile range, 4-7] vs 7 [5-8]; P < .001). When helmet CPAP is delivered through gas flow rates up to 50 L/min, an HME placed on the helmet inlet gas port should be used to reduce noise inside the helmet and to improve patients' comfort.

Oxigenoterapia en COVID-19: herramientas de uso previo a la ventilación mecánica invasiva. Guía simple

Los pacientes con síndrome de dificultad respiratoria aguda secundario a COVID-19, tienen una forma de presentación atípica, con una discrepancia entre una mecánica pulmonar aceptable y una hipoxia marcada. Cada uno de los métodos de oxígeno suplementario usados en la práctica clínica en pacientes con COVID-19 tiene descritas sus indicaciones, ventajas y desventajas. La cánula nasal es el sistema más común y se recomienda en casos de hipoxia leve. El sistema Venturi, que utiliza fracción inspirada de oxígeno exacta con flujos más altos de oxígeno y, la máscara de no re-inhalación, que normalmente se usa ante la falta de respuesta con los dispositivos anteriores, tiene riesgo de producir aerosoles y transmitir la infección. Otra herramienta muy útil es la cánula de alto flujo, la cual es bien tolerada, reduce el trabajo respiratorio, ayuda a prevenir la intubación, es ideal en caso de no tener ventiladores disponibles y cuando los métodos de oxígeno suplementario sean insuficientes para lograr las metas de saturación de oxígeno. En cuanto a la ventilación mecánica no invasiva, existen reportes donde se usa; sin embargo, si el paciente no responde a los tratamientos mencionados, debe ser candidato a ventilación mecánica invasiva sin retraso. Los criterios de intubación orotraqueal son tanto clínicos como gasimétricos. Las metas de saturación de oxígeno son, en general 90-96 %, y no se debe retrasar la intubación y la ventilación mecánica en caso de tener la indicación. Son necesarios más estudios que evalúen la eficacia clínica de los distintos métodos de oxigenación y de soporte ventilatorio no invasivo en estos pacientes.

Water content of delivered gases during Helmet Continuous Positive Airway Pressure in healthy subjects.

Introduction: During Continuous Positive Pressure Ventilation delivered through helmet, the patient inhales high flows of gas without adequate conditioning. However, the need to humidify the inspired gas during Helmet-CPAP, has not been sufficiently explored. Methods: Experimental design study. Six healthy individuals underwent High Flow Helmet CPAP with different gas flows (60 and 80 L/min) and FiO2 (0.35, 0.5, 0.7 and 1) generated by a Venturi system, with and without active humidification. The active humidifier setting was 26 ° at the humidification chamber and 28 ° at the helmet gas inlet. At each setting, measurements about temperature and relative humidity inside helmet were taken. Comfort level at each setting was evaluated using a visual analog scale rated from 0 to 10. Results: Without heated humidification, the mean value of absolute humidity in the eight combinations investigated was 5.9±2.1 mg H2O/L, with a mean temperature of 25.8±0.9°. With heated humidification mean absolute humidity was 15.0±3.5 mg H2O/L with mean temperature of 29.0±0.1°. The median comfort scale value was 6 (IQR: 5.25-6.75) during the phase without humidification vs 8 (7.25-8.0 - P<0.01) when active humidification was applied. Conclusions: In healthy subjects undergoing High Flow Helmet CPAP, heated humidifiers with heated wires tubes are necessary to avoid the under-humidification inside the helmet. To obtain patient’s comfort and airways mucosal humidification during continuous Helmet CPAP, the most desirable conditions are reached by heated humidifiers with a humidifying chamber temperature settled between 26-28°C. (www.actabiomedica.it)

Study on the accuracy of oxygen concentration of modified oxygen treatment with Venturi and humidity system

To verify the accuracy of oxygen concentration (FiO2) of modified oxygen treatment with Venturi and humidity system. Patients just after ventilator weaning and before the removal of tracheal intubation/tracheotomy tube, who admitted to the intensive care unit (ICU) of Henan Provincial People's Hospital from May 1st to December 15th in 2017, were enrolled. All patients were given a modified oxygen treatment with Venturi and humidity system, and the oxygen flow rate (Flow) of the Venturi device and the oretical value of FiO2 were adjusted according to the patient's condition. Patients were divided into five groups based on doctor's orders: Flow 3 L/min FiO2 0.24, Flow 3 L/min FiO2 0.26, Flow 6 L/min FiO2 0.28, Flow 6 L/min FiO2 0.30, Flow 9 L/min FiO2 0.35. The value of FiO2 at the inhalation end of patients of each group was measured by TSI airflow analyzer, and the consistency between the measured value of FiO2 at the inhalation end and the FiO2 marked value of Venturi was compared and analyzed. When the FiO2 theoretical value of Venturi were adjusted to 0.24, 0.26, 0.28, 0.30, and 0.35, the measured values of FiO2 at the inhalation end of patients were 0.38±0.05, 0.38±0.05, 0.40±0.04, 0.41±0.04, and 0.77±0.11, respectively, which were all significantly higher than the theoretical value of FiO2 (all P < 0.01). The difference between the measured value of FiO2 at the inhalation side and the FiO2 value of the Venturi annotated and the difference rate were both "V"-shaped, both of which decreased with the increase in theoretical value of FiO2 to a Flow of 9 L/min and a theoretical value of FiO2 0.35, the accuracy was the worst, with the FiO2 difference of 0.42±0.11, and the FiO2 difference rate of (121.6±36.5)%. There is a difference between the measured value and the theoretical value of FiO2 at the inhalation end of the modified Venturi oxygen therapy humidification system, which needs to be paid attention to during clinical oxygen therapy.