Different Modes Of Ventilation Research Articles

Study of gas exchange under different modes of ventilation in yoga breathing exercises

Yoga breathing exercises that develop the ability to voluntarily regulate the minute volume of respiration (MV) and maintain the state of hypoventilation, hypoxia and hypercapnia, can be considered as a way of hypoxic-hypercapnic training, potentially capable of influencing cerebral circulation and neuroprotective factors. However, at the moment, individual anthropometric features that affect the ability to develop a hypoventilation mode of breathing have not been studied, and methodological criteria for training have not been developed.Methods: The study involved 44 people (32 men and 12 women) who regularly practice yoga breathing techniques with a voluntary decrease in respiratory rate using maximum tidal volume (TV). Free breathing was recorded for 2 minutes, then each subject performed the respiratory hypoventilation pattern available to him or her (minimum RR values with maximum TV, inhalation and exhalation were of equal duration). The following parameters of external respiration were determined: respiratory rate (RR), minute ventilation (MV), tidal volume (TV), partial pressure of CO2 in the exhaled air at the end of exhalation (PetCO2 ), percentage of O2 in the exhaled air (FeO2) and hemoglobin saturation (SpO2 ).Results: Compared to breathing at rest (MV = M±SD 8.51 ± 2.57 (95% CI 7.72–9.29) l/min; PetCO2 = M±SD 36.98 ± 3.71 (95% CI 35.85–38.11) mm Hg), the mode with RR = 3 times/min (inspiration and expiration for 10 s), n = 44, leads to an increase in MV up to M±SD 12.02 ± 3.42 (95% CI 10.98–13.06) l/min (p < 0.001) and a decrease of CO2 : PetCO2 = M±SD 33.99 ± 3.59 (95% CI 32.90–35.08) mm Hg (p < 0.001) — that is, to development of alveolar hypocapnia. The mode with RR = 1.5 times/min (inhalation and exhalation for 20 s), n = 44, demonstrates a decrease in MV to M±SD 5.95 ± 1.59 (95% CI 5.46–6.43) l/min (p < 0.001) and growth of PetCO2 up to M±SD 41.19 ± 3.71 (95% CI 40.06–42.32) mm Hg (p < 0.001). The mode with RR = 1 time/min (inspiration and exhalation for 30 s), n = 24: with a decrease in RR to 1 time/min, a decrease in MV was observed to M±SD 4.22 ± 0.92 (95% CI 3.83–4.61) l / min (p < 0.001) and an increase in PetCO2 up to M±SD 44.05 ± 3.05 (95% CI 42.76–45.33) mm Hg (p < 0.001). The breathing pattern with RR = 1 r/min is accompanied by a statistically significant decrease in MV compared to rest, as well as an increase in PetCO2 and a decrease in FeO2 , that is, it is hypoventilation. We have proposed a ventilation coefficient (Qvent), which is the ratio MV/VC, which allows us to judge at what values of MV an individual reaches a state of hypoventilation. It was previously shown in this sample that the breathing exercise becomes hypoventilation when Qvent values are equal to or less than 1. With Qvent in the range from 1 to 2, the ventilation mode is within normal values, and when Qvent is more than 2, hyperventilation occurs.Conclusion: when performing yoga breathing exercises, variations in MV are observed both in the direction of hyperventilation and in the direction of hypoventilation with corresponding shifts in gas exchange (hypocapnia with hyperventilation, hypercapnia with hypoventilation). The MV values at which an individual reaches hypoventilation vary from person to person and can be predicted using the ventilation coefficient (Qvent).

Effect of Ventilator Settings on Mechanical Power During Simulated Mechanical Ventilation of Patients With ARDS.

In recent years, mechanical power (MP) has emerged as an important concept that can significantly impact outcomes from mechanical ventilation. Several individual components of ventilatory support such as tidal volume (VT), breathing frequency, and PEEP have been shown to contribute to the extent of MP delivered from a mechanical ventilator to patients in respiratory distress/failure. The aim of this study was to identify which common individual setting of mechanical ventilation is more efficient in maintaining safe and protective levels of MP using different modes of ventilation in simulated subjects with ARDS. We used an interactive mathematical model of ventilator output during volume control ventilation (VCV) with either constant inspiratory flow (VCV-CF) or descending ramp inspiratory flow, as well as pressure control ventilation (PCV). MP values were determined for simulated subjects with mild, moderate, and severe ARDS; and whenever MP > 17 J/min, VT, breathing frequency, or PEEP was manipulated independently to bring back MP to ≤ 17 J/min. Finally, the optimum VT-breathing frequency combinations for MP = 17 J/min were determined with all 3 modes of ventilation. VCV-CF always resulted in the lowest MPs while PCV resulted in highest MPs. Reductions in VT were the most efficient for maintaining safer and protective MP. At targeted MPs of 17 J/min and maximized minute ventilation, the optimum VT-breathing frequency combinations were 250-350 mL for VT and 32-35 breaths/min for breathing frequency in mild ARDS, 200-350 mL for VT and 34-40 breaths/min for breathing frequency in moderate ARDS, and 200-300 mL for VT and 37-45 breaths/min for breathing frequency for severe ARDS. VCV-CF resulted in the lowest MP. VT was the most efficient for maintaining safe and protective MP in a mathematical simulation of subjects with ARDS. In the context of maintaining low and safe MPs, ventilatory strategies with lower-than-normal VT and higher-than-normal breathing frequency will need to be implemented in patients with ARDS.

Lung- and diaphragm-protective strategies in acute respiratory failure: an in silico trial

BackgroundLung- and diaphragm-protective (LDP) ventilation may prevent diaphragm atrophy and patient self-inflicted lung injury in acute respiratory failure, but feasibility is uncertain. The objectives of this study were to estimate the proportion of patients achieving LDP targets in different modes of ventilation, and to identify predictors of need for extracorporeal carbon dioxide removal (ECCO2R) to achieve LDP targets.MethodsAn in silico clinical trial was conducted using a previously published mathematical model of patient–ventilator interaction in a simulated patient population (n = 5000) with clinically relevant physiological characteristics. Ventilation and sedation were titrated according to a pre-defined algorithm in pressure support ventilation (PSV) and proportional assist ventilation (PAV+) modes, with or without adjunctive ECCO2R, and using ECCO2R alone (without ventilation or sedation). Random forest modelling was employed to identify patient-level factors associated with achieving targets.ResultsAfter titration, the proportion of patients achieving targets was lower in PAV+ vs. PSV (37% vs. 43%, odds ratio 0.78, 95% CI 0.73–0.85). Adjunctive ECCO2R substantially increased the probability of achieving targets in both PSV and PAV+ (85% vs. 84%). ECCO2R alone without ventilation or sedation achieved LDP targets in 9%. The main determinants of success without ECCO2R were lung compliance, ventilatory ratio, and strong ion difference. In silico trial results corresponded closely with the results obtained in a clinical trial of the LDP titration algorithm (n = 30).ConclusionsIn this in silico trial, many patients required ECCO2R in combination with mechanical ventilation and sedation to achieve LDP targets. ECCO2R increased the probability of achieving LDP targets in patients with intermediate degrees of derangement in elastance and ventilatory ratio.

Factors associated with decreased compliance after on-site extracorporeal membrane oxygenation cannulation for acute respiratory distress syndrome: A retrospective, observational cohort study

BackgroundExtracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) is systematically associated with decreased respiratory system compliance (CRS). It remains unclear whether transportation to the referral ECMO center, changes in ventilatory mode or settings to achieve ultra-protective ventilation, or the natural evolution of ARDS drives this change in respiratory mechanics. Herein, we assessed the precise moment when CRS decreases after ECMO cannulation and identified factors associated with decreased CRS. MethodsTo rule out the effect of transportation and the different modes of ventilation on CRS, we conducted a retrospective, single-center, observational cohort study from January 2013 to May 2020, on 22 patients with severe ARDS requiring on-site ECMO and ventilated in pressure-controlled mode to achieve ultra-protective ventilation. CRS was assessed at different time points ranging from 12 h before ECMO cannulation to 72 h after ECMO cannulation. The primary outcome was the relative change in CRS between 3 h before and 3 h after ECMO cannulation. The secondary outcomes included variables associated with the relative changes in CRS within the first 3 h after ECMO cannulation and the relative changes in CRS at each time point. ResultsCRS decreased within the first 3 h after ECMO cannulation (−28.3%, 95% confidence interval [CI]: −38.8 to −17.9, P<0.001), while the decrease was mild before and after these first 3 h after ECMO cannulation. To achieve ultra-protective ventilation, respiratory rate decreased in the mean by –13 breaths/min (95% CI: −15 to −11) and driving pressure by −8.3 cmH2O (95% CI: −11.2 to −5.3), resulting in decreased tidal volume by −3.3 mL/kg of predicted body weight (95% CI: −3.9 to −2.6) as compared to before ECMO cannulation (P <0.001 for all). Plateau pressure reduction, driving pressure reduction, and tidal volume reduction were significantly associated with decreased CRS after ECMO cannulation, whereas neither respiratory rate, positive end-expiratory pressure, inspired fraction of oxygen, fluid balance, nor mean airway pressure was associated with decreased CRS. ConclusionsDecreased driving pressure resulting in lower tidal volume to achieve ultra-protective ventilation after ECMO cannulation was associated with a marked decrease in CRS in ARDS patients with on-site ECMO cannulation.

Perioperative lung function following flow controlled ventilation for robot-assisted prostatectomies in steep trendelenburg position: an observational study

BackgroundSteep Trendelenburg position combined with capnoperitoneum can lead to pulmonary complications and prolonged affection of postoperative lung function. Changes in pulmonary function occur independent of different modes of ventilation and levels of positive end-expiratory pressure (PEEP). The effect of flow-controlled ventilation (FCV) has not been evaluated yet. We perioperatively measured spirometric lung function parameters in patients undergoing robot-assisted prostatectomy under FCV. Our primary hypothesis was that there is no significant difference in the ratio of the maximal mid expiratory and inspiratory flow (MEF50/MIF50) after surgery.MethodsIn 20 patients, spirometric measurements were obtained preoperatively, 40, 120, and 240 min and 1 and 5 days postoperatively. We measured MEF50/MIF50, vital capacity (VC), forced expiratory volume in 1 s (FEV1), and intraoperative ventilation parameters.ResultsMEF50/MIF50 ratio increased from 0.92 (CI 0.73–1.11) to 1.38 (CI 1.01–1.75, p < 0.0001) and returned to baseline within 24 h, while VC and FEV1 decreased postoperatively with a second nadir at 24 h and only normalized by the fifth day (p < 0.0001). Compared to patients with PCV, postoperative lung function changes similarly.ConclusionFlow-controlled ventilation led to changes in lung function similar to those observed with pressure-controlled ventilation. While the ratio of MEF50/MIF50 normalized within 24 h, VC and FEV1 recovered within 5 days after surgery.

Mechanical ventilator flow and pressure sensors: Does location matter?

Introduction Accurate measurements of ventilatory outputs are crucial during mechanical ventilation support. These measurements are achieved through sensors that monitor parameters such as flow/volumes and pressures. External and internal flow sensors are both commonly used in mechanical ventilation systems to measure the flow of air entering and leaving the patient’s lungs. The sensors could be located outside the ventilator (external or proximal) or inside the ventilator (internal or distal), each of which have their own respective advantages and disadvantages. There are differences in the way they function and the information they provide, which can affect their accuracy and usefulness in different clinical situations. A few clinical studies have compared the use of external to internal sensors in mechanical ventilation, showing mixed results. The intent of this study is to reexamine the differences between two critical care ventilators utilizing external sensors to two other ventilators utilizing internal sensors. Methods A bench study using a lung simulator was conducted. We constructed three passive, single compartment models: 1) compliance of 40 ml/cmH2O, resistance of 10 cmH2O, 2) compliance of 40 ml/cmH2O, resistance of 20 cmH2O, 3) compliance of 20 ml/cmH2O, resistance of 10 cmH2O. In each experiment we used two different modes of ventilation, volume controlled (tidal volume 400 ml, respiratory rate 20, PEEP 5 cmH2O, inspiratory time 0.7 seconds) and pressure controlled (inspiratory pressure 15 cmH2O, respiratory rate 20, PEEP 5cmH2O, inspiratory time 0.7 seconds). We compared the inspiratory flow, inspiratory tidal volume, peak inspiratory pressures and PEEP in four commercially available critical care ventilators. Two use external flow sensors: G5 (Hamilton Medical), Bellavista 1000e (Vyaire Medical), and two use internal flow sensors: Evita Infinity 500 (Drager), and PB 980 (Medtronic). We also compared these parameters to a mathematical model. Statistics to compare the parameters in all four ventilators were done with Kruskal Wallis test followed by post-hoc Dunn’s test. A t-test was used to compare the parameters between the ventilator-measured and simulator-measured parameters in each ventilator. A P value of &lt; 0.05 was considered significant. Results There were statistically significant differences (P &lt; 0.001) in all four measured parameters: inspiratory flow, tidal volume, PIP and PEEP between all four ventilators, and between the mathematical model and all four ventilators in both modes, in all three clinical scenarios. The post-hoc Dunn test showed significant differences between each ventilator, except for a few parameters in PIP and PEEP. but not in flow or volume. There were variable but significant differences between some of the four parameters measured from the ventilator compared to those measured from the simulator of all four ventilators in both modes. The two ventilators using external sensors had more accurate differences between the delivered and measured tidal volumes (P &lt; 0.001) and inspiratory flow (P &lt; 0.001), however, the other two ventilators with internal sensors had more accurate differences between the delivered and measured PIP (P &lt; 0.001) and PEEP (P &lt; 0.001) levels. Conclusions All four ventilators performed differently from each other and from the mathematical model. The two ventilators using external sensors had more accurate differences between the delivered and measured tidal volumes and inspiratory flow, the two ventilators with internal sensors had more accurate differences between the delivered and measured PIP and PEEP levels. Differences between the ventilators depends on multiple factors including location, type of sensor, and respiratory mechanics. Keywords Flow sensor, Pressure sensor, PIP, PEEP, Tidal volume, Flow

Effect of different modes of ventilation on diaphragmatic excursion in mechanically ventilated patients: ultrasonographic assessment

Effect of different modes of ventilation on diaphragmatic excursion in mechanically ventilated patients: ultrasonographic assessment

The Evolution of Intermittent Mandatory Ventilation.

Intermittent mandatory ventilation (IMV) is one kind of breath sequence used to classify a mode of ventilation. IMV is defined as the ability for spontaneous breaths (patient triggered and patient cycled) to exist between mandatory breaths (machine triggered or machine cycled). Over the course of more than a century, IMV has evolved into 4 distinct varieties, each with its own advantages and disadvantages in serving the goals of mechanical ventilation (ie, safety, comfort, and liberation). The purpose of this paper is to describe the evolution of IMV, review relevant supporting evidence, and discuss the rationales for each of the 4 varieties. Also included is a brief overview of the background information required for a proper perspective of the purpose and design of the innovations. Understanding these different forms of IMV is essential to recognizing the similarities and differences among many dozens of different modes of ventilation. This recognition is important for clinical application, education of caregivers, and research in mechanical ventilation.

Lung resistance and elastance are different in ex vivo sheep lungs ventilated by positive and negative pressures.

Lung resistance (RL) and elastance (EL) can be measured during positive or negative pressure ventilation. Whether the different modes of ventilation produce different RL and EL is still being debated. Although negative pressure ventilation (NPV) is more physiological, positive pressure ventilation (PPV) is more commonly used for treating respiratory failure. In the present study, we measured lung volume, airway diameter, and airway volume, as well as RL and EL with PPV and NPV in explanted sheep lungs. We found that lung volume under a static pressure, either positive or negative, was not different. However, RL and EL were significantly higher in NPV at high inflation pressures. Interestingly, diameters of smaller airways (diameters <3.5 mm) and total airway volume were significantly greater at high negative inflation pressures compared with those at high positive inflation pressures. This suggests that NPV is more effective in distending the peripheral airways, likely due to the fact that negative pressure is applied through the pleural membrane and reaches the central airways via the peripheral airways, whereas positive pressure is applied in the opposite direction. More distension of lung periphery could explain why RL is higher in NPV (vs. PPV), because the peripheral parenchyma is a major source of tissue resistance, which is a part of the RL that increases with pressure. This explanation is consistent with the finding that during high frequency ventilation (>1 Hz, where RL reflects airway resistance more than tissue resistance), the difference in RL between NPV and PPV disappeared.

Modes of ventilation for pediatric patients under anesthesia: APro/Con conversation.

The development of sophisticated modes of ventilation for pediatric patients undergoing anesthesia is ongoing; what remains a challenge for the pediatric anesthesiologist is thoughtful selection of the mode(s) of ventilation for a particular patient in the context of the surgical procedure and the goals of the anesthetic. This article provides some historical accounting of a variety of modes of ventilation, defines the terminology of modern ventilatory modes, and reviews in detail the benefits and pitfalls of the specific modes of ventilation and their applicability to the practice of pediatric anesthesiology. In an attempt to debate the Pros and Cons of different modes of ventilation, and to finally resolve the debate "spontaneous vs. controlled ventilation," we share with you a thoughtful conversation of the continuum of modes of ventilation and their applicability to our pediatric anesthesia population.

Сравнение влияния разных режимов искусственной вентиляции легких на церебральную перфузию у новорожденных с гипоксически-ишемической энцефалопатией

Актуальность. На сегодняшний день нет опубликованных результатов крупных рандомизированных контролируемых исследований, которые сравнивали бы дифференцированное влияние различных режимов искусственной вентиляции легких на состояние церебральной перфузии у новорожденных с гипоксически-ишемической энцефалопатией (ГИЭ). Перспективным является применение нового режима вентиляции Neurally Adjusted Ventilatory Assist (NAVA), который уже доказал свои преимущества у недоношенных младенцев. Цель исследования: сравнить влияние Neurally Adjusted Ventilatory Assist и других режимов искусственной вентиляции легких на состояние мозгового кровотока в остром периоде ГИЭ у доношенных новорожденных. Материалы и методы. В исследование включено 205 доношенных новорожденных с гипоксически-ишемической энцефалопатией по Sarnat II–III ст. в сроке ≤ 72 часов после родов. Младенцы были рандомизированы на исследуемую группу с применением NAVA (n = 16) и группу контроля (n = 189), в которую вошли такие режимы вентиляции, как PC, SIMV/PSV и PRVC. Проведен мультивариантный дисперсионный анализ влияния NAVA и других режимов вентиляции на состояние церебральной перфузии в остром периоде неонатальной гипоксически-ишемической энцефалопатии. Результаты. На третий день лечения в конце периода терапевтической гипотермии и начала согревания получено достоверное различие между группами в отношении допплеровского индекса мозгового кровотока RI (0,70 [0,67–0,74] в группе NAVA и 0,66 [0,58–0,72] в группе контроля, р = 0,021) и пульсационного индекса РІ (1,3 [1,2–1,5] в группе NAVA и 1,2 [1,0–1,40] в группе контроля, р = 0,032). Также результаты теста ANOVA подтвердили, что по сравнению с другими режимами вентиляции NAVA имел статистически достоверное положительное влияние на 2-й и 3-й день наблюдения как на величину RI (р = 0,009), так и на РІ (р = 0,012). Выводы. Режим вентиляции Neurally Adjusted Ventilatory Assist продемонстрировал положительное влияние на индексы церебральной перфузии у доношенных новорожденных в остром периоде ГИЭ по сравнению с традиционными режимами PC, SIMV/PSV и PRVC.

Quantifying Delivered Dose with Jet and Mesh Nebulizers during Spontaneous Breathing, Noninvasive Ventilation, and Mechanical Ventilation in a Simulated Pediatric Lung Model with Exhaled Humidity.

Acutely ill children may transition between spontaneous breathing (SB), noninvasive ventilation (NIV), and mechanical ventilation (MV), and commonly receive the same drug dosage with each type of ventilatory support and interface. This study aims to determine the aerosol deposition with jet (JN) and mesh nebulizers (MN) during SB, NIV, and MV using a pediatric lung model. Drug delivery with JN (Mistymax10) and MN (Aerogen Solo) was compared during SB, NIV, and MV using three different lung models set to simulate the same breathing parameters (Vt 250 mL, RR 20 bpm, I:E ratio 1:3). A heated humidifier was placed between the filter and test lung to simulate exhaled humidity (35 ± 2 °C, 100% RH) with all lung models. Albuterol sulfate (2.5 mg/3 mL) was delivered, and the drug deposited on an absolute filter was eluted and analyzed with spectrophotometry. Aerosol delivery with JN was not significantly different during MV, NIV, and SB (p = 0.075), while inhaled dose obtained with MN during MV was greater than NIV and SB (p = 0.001). The delivery efficiency of MN was up to 3-fold more than JN during MV (p = 0.008), NIV (p = 0.005), and SB (p = 0.009). Delivered dose with JN was similar during MV, NIV, and SB, although the delivery efficiency of MN differs with different modes of ventilation.

Efficacy and safety of an open lung ventilation strategy with staircase recruitment followed by comparison on two different modes of ventilation, in moderate ARDS in cirrhosis: A pilot randomized trial.

BackgroundMechanical ventilation in cirrhosis with acute respiratory distress syndrome (ARDS) is not widely studied. We aimed to study the effect of the staircase recruitment manoeuvre followed by two different modes of ventilation.MethodsThirty patients with cirrhosis with moderate ARDS underwent the staircase recruitment manoeuvre followed by randomisation to volume control or pressure control group.ResultsThe PaO2/FiO2 ratio showed a significant improvement in both the groups after recruitment. The improvement was significantly higher in the pressure control ventilation (PCV) group at the end of the first hour as compared to the volume control ventilation (VCV) group. However, this difference was not significant at the end of 6 and 12 h. In the PCV group it improved from 118.47 ± 10.21 at baseline to 189.87 ± 55.18 12 h post-recruitment. In the VCV group it improved from 113.79 ± 13.22 at baseline to 180.93 ± 81.971. Static lung compliance also improved in both the groups significantly (P < 0.001). The PCV group showed an improvement from 25.42 ± 11.94 mL/cm H2O at baseline to 29.51 ± 14.58 mL/cm H2O. In the VCV group the lung compliance improved from 24.78 ± 4.87 mL/cm H2O to 31.31 ± 10.88 mL/cm H2O.ConclusionThis study shows that stepwise recruitment manoeuvre is an effective rescue therapy to improve oxygenation in cirrhosis with moderate ARDS. PCV may have an advantage over VCV in terms of better oxygenation.

Development of a tool to predict the socio-economic consequences of better air quality and temperature control in classrooms

A simplified modelling framework for the prediction of the indoor environment, energy use and socio-economic consequences of improving air quality and temperature in school buildings is suggested. The framework combines established models for infiltration and different modes of ventilation to estimate yearly distributions of the classroom temperature and CO2 concentration. These distributions are used as input to a prediction of pupil performance of schoolwork, their attendance at school, and teacher absence before and after refurbishment of their school building. Eventually, the framework estimates the socio-economic consequences of an improved classroom environment for a school and may be used to evaluate the feasibility of a range of different refurbishment scenarios and support decisions on building upgrades.

Comparison of volume guarantee and volume-controlled ventilation both using closed loop inspired oxygen in preterm infants: a randomised crossover study (CLIO-VG study)

ObjectiveThe objective of this study was to compare two different modes of ventilation in maintaining oxygen saturation (SpO2) in target range (90%–95%) in ventilated preterm infants cared for with automatic...

Hemodynamic outcome of different ventilation modes in laparoscopic surgery with exaggerated trendelenburg: a randomised controlled trial

PurposeTo compare hemodynamic effects of two different modes of ventilation (volume-controlled and pressure-controlled volume guaranteed) in patients undergoing laparoscopic gynecology surgeries with exaggerated Trendelenburg position. MethodsThirty patients undergoing laparoscopic gynecology operations were ventilated using either volume-controlled (Group VC) or pressure-controlled volume guaranteed mode (Group PCVG) (n = 15 for both groups). Hemodynamic variables were measured using Pressure Recording Analytical Method by radial artery cannulation in addition to peak and mean airway pressures and expired tidal volume. ResultsThe only remarkable finding was a more stable cardiac index in Group PCVG, where other hemodynamic parameters were similar. Expired tidal volume increased in Group VC while peak airway pressure was lower in Group PCVG. ConclusionPCV-VG causes less hemodynamic perturbations as measured by Pressure Recording Analytical Method (PRAM) and allows better intraoperative hemodynamic control in exaggerated Trendelenburg position in laparoscopic surgery.

Mechanical Ventilator for Respiratory Impaired Persons: A Review

Mechanical ventilator is one of the most important devices used in anesthesia and intensive care units for generating a regulated flow of gas into a patient’s lungs. Oxygen is required by every human to stay alive and in cases where a patient is undergoing an acute respiratory distress, a mechanical ventilator is used to deliver external ventilation which could be generated from a hospital’s built in supply system or from a portable oxygen generator. The ventilator is connected to the patient’s lungs through an endotracheal tube (ETT) to deliver air by compressing a conventional bag-valve mask (BVM) with a pivoting cam arm, thereby eliminating the need for a human operator. The device also operates by setting some parameters which can be predetermined by clinicians as well as an assist control mode and an alarm to determine when the system is over pressured. The paper focuses on review of Mechanical ventilators, the different modes of ventilation, anatomy tract of the respiratory system, respiratory mechanics, and approaches of ventilation.

Comparison of Spontaneous Ventilation, Pressure Control Ventilation and Pressure Support Ventilation in Pediatric Patients Undergoing Infraumbilical Surgery Using ProSeal Laryngeal Mask Airway.

Background:Pediatric infraumbilical surgeries are often performed under general anaesthesia using different modes of ventilation through Laryngeal Mask Airway .Although controlled ventilation has been successfully used, very less studies have been done to compare them with spontaneous ventilation for short duration surgeries.Aims:We tried to measure quantitave differences in haemodynamic and respiratory parameters and assess the recovery profile between controlled and spontaneous ventilation using Proseal LMA.Settings and Design:This was a prospective, randomized, double-blind study that comprised 90 American Society of Anaesthesiologist (ASA) classes I and II pediatric patients posted for infra umbilical surgery.Materials and Methods:90 paediatric patients undergoing infraumbilical surgeries were included. Three different ventilation strategies: spontaneous , pressure support and pressure-controlled ventilation were applied depending on attending anaesthesiologist's preference. Haemodynamic and respiratory parameters were recorded during the procedure. Post procedure parameters including need for supplementary oxygen, recovery time, complications were recorded.Statistical Methods:Analysis of variance (ANOVA) was employed for inter group analysis and for multiple comparisons, least significant difference (LSD) test was applied. Chi-square test or Fisher's exact test, whichever appropriate, was used for comparison of categorical variables.Results:The mean time interval between end of surgery and removal of LMA was significantly higher in PCV group in comparison to SV and PSV groups. In SV group lesser number of patients required oxygen supplementation and had shorter stay in recovery than PCV group.Conclusion:We conclude that spontaneous mode of ventilation can be used as safely as controlled /assist ventilation mode in short duration surgeries in high turn over settings.

Developing Algorithms and Programs for an Artificial Lung Ventilator

Описаны алгоритмы и программы для аппарата искусственной вентиляции легких, которые обеспечивают различные режимы работы аппарата. Работа является актуальной в условиях пандемии COVID-19 в связи с возросшим спросом на данные устройства.Цель исследования – разработка программного комплекса для микроконтроллера STM32L151ZDTx-LQFP144, используемого на переносном аппарате ИВЛ Axion A-IVL-E-03 и обеспечивающего работу в различных режимах вентиляции, графическое отображение динамики дыхания на дисплее и подачу оператору голосовых подсказок и световых сигналов во время работы. Разработанные алгоритмы также предназначены для управления периферийными устройствами и контроля правильности их работы, разрешения аварийных ситуаций с помощью дисплея, голосовых подсказок и световой индикации. Кроме того, в качестве инструмента, который позволяет врачу понять важное взаимодействие между входными параметрами пациента (частота, давление в дыхательных путях и степень вдоха) и клинически важными параметрами (дыхательный объем, средний объем минутной вентиляции), предложены математические модели вентиляции легких с контролируемым давлением. Реализация данных математических моделей показала их применимость для симуляции данных сложных процессов. Разработан удобный и интуитивно понятный графический пользовательский интерфейс.В статье также приводится сравнение существующих аналогов с предложенными разработками.

Numerical study on heat transfer between airflow and surrounding rock with two major ventilation models in deep coal mine

Not only is the thermal environment of the coal mining face related to the temperature of the surrounding rock, it is also closely associated with the ventilation model of the working face. In this study, the numerical methods were applied to study the impact of two major ventilation systems on the airflow temperature of working face in coalmine. Firstly, a heat transfer model of the surrounding rock and airflow was established to reveal that the wall roughness of the surrounding rock could enhance heat transfer between the surrounding rock and the airflow. Moreover, an analysis was conducted of the heat transfer between the airflow and the surrounding rock under different modes of ventilation in the first mining face. According to the analytical results, the temperature of airflow in the U-type ventilation system is lower than in the Y-type ventilation system. For the next adjacent coal mining face, however, the Y-type ventilation system is more conducive in reducing the temperature of the airflow. Therefore, with regard to the mine as a whole, the Y-type ventilation system is more effective than a U-type system in reducing heat and humidity in the ambient environment.