Pressure-controlled Ventilation Research Articles

Ventilation Induces Changes in Pulse Wave Transit Time in the Pulmonary Artery.

Pulse wave transit time (PWTT) shortens as pulmonary artery pressure (PAP) increases and was therefore suggested as a surrogate parameter for PAP. The aim of this analysis was to reveal patterns and potential mechanisms of ventilation-induced periodic changes in PWTT under resting conditions. To measure both PWTT and PAP in five healthy pigs, two pulmonary artery Mikro-Tip™ catheters were inserted into the pulmonary vasculature: one with the tip placed in the pulmonary artery trunk, and a second one placed in a distal segment of the pulmonary artery. Animals received pressure-controlled mechanical ventilation. Ventilation-dependent changes were seen in both variables, PWTT and mean PAP; however, changes in PWTT were not synchronous with changes in PAP. Thus, plotting the value of PWTT for each heartbeat over the respective PAP revealed a characteristic hysteresis. At the beginning of inspiration, PAP rose while PWTT remained constant. During further inspiration, PWTT started to decrease rapidly as mPAP was about to reach its plateau. The same time course was observed during expiration: while mPAP approached its minimum, PWTT increased rapidly. During apnea this hysteresis disappeared. Thus, non-synchronous ventilation-induced changes in PWTT and PAP were found with inspiration causing a significant shortening of PWTT. Therefore, it is suggested that the respiratory cycle should be considered when using PWTT as a surrogate for PAP.

Volume-Controlled, Pressure-Controlled vs. Pressure-Controlled Volume-Guaranteed Ventilations in Improving Respiratory Dynamics During Laparoscopic Cholecystectomy

Introduction: Pressure-controlled volume-guaranteed (PCV-VG) mode has the advantage of both volume-controlled (VCV) and pressure-controlled ventilation (PCV). Our objective is to compare gaseous exchange and lung dynamic compliance (C dyn) after pneumoperitoneum and just before desufflation in VCV, PCV, and PCV-VG mode in laparoscopic cholecystectomy (LC). Materials and Methods: A total of 105 patients undergoing LC under general anesthesia were randomly distributed to group V (received VCV), group P (PCV), and group PV (PCV-VG) as mode of ventilation. Two arterial blood samples were taken for blood gas analysis: after the pneumoperitoneum (T1) and right before abdominal desufflation (T2). Arterial partial oxygen pressure (PaO2) and carbon dioxide (PaCO2) levels, oxygen saturation (SpO2) and end-tidal carbon dioxide were compared at these two points of time between the groups. Results: C dyn was higher in group P (43.21 ± 4.4 mL/cmH2O) compared with group V (39.18 ± 3.2 mL/cmH2O) and PV (40.37 ± 2.45 mL/cmH2O) at T2 (P < 0.001). PaO2 was significantly higher (P < 0.001) in group P (197.50 ± 17.29 mm Hg) at T2 compared with group V (178.90 ± 23.7 mm Hg) and PV (183.47 ± 22.99 mm Hg). Furthermore, PaCO2 was also significantly higher in Group P (40.19 ± 2.92 mm Hg) compared with group V (32.57 ± 2.09 mm Hg) and group PV (34.14 ± 3.27 mm Hg). Conclusion: PaO2 and dynamic compliance are higher in pressure-controlled mode but, high PaCO2 in pressure-controlled mode indicates inadequate ventilation. Therefore, pressure controlled volume guaranteed mode can be considered as a favorable ventilation strategy during LC because dynamic compliance and PaO2 are higher than volume controlled ventilation and PaCO2 is significantly less than pressure controlled mode.

Effect of volume-controlled and pressure-controlled ventilation modes on cerebral oximetry in laparoscopic cholecystectomy: a randomized controlled trial

This study aimed to compare the effect of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) modes on cerebral oximetry during laparoscopic cholecystectomy using near-infrared spectroscopy (NIRS). Seventy patients who underwent elective laparoscopic cholecystectomy were randomized to receive either VCV (group V) or PCV (group P). Demographic and operative data (anesthesia, surgery and insufflation durations) were recorded. The primary outcome was the NIRS value, while the secondary outcomes were peripheral oxygen saturation (SpO2), blood gas parameters and peak and plateau pressures in mechanical ventilation. Measurements were conducted at the start of anesthesia (T0), end of intubation (T1), 5 min after insufflation (T2), just before desufflation (T3), and 5 min after desufflation (T4). Both groups were comparable in terms of age, sex, body mass index, intraoperative time, anesthesia and insufflation durations. The average NIRS right T1–T2–T3 and left T2–T3 values were significantly higher in group P than in group V (p = 0.030, p = 0.001, p = 0.001, p = 0.006 and p = 0.002 respectively). In contrast, the mean peak and mean plateau pressures in group P at T1, T2 and T4 were significantly lower than those in group V (p = 0.003, p = 0.001, p < 0.001, p = 0.011, p = 0.001 and p < 0.001 respectively).The PCV mode allows better cerebral oxygenation than VCV while maintaining lower peak pressure and plateau pressures.

Comparison Between Volume Controlled Ventilation and Pressure Controlled Ventilation in Laparoscopic Cholecystectomy and their Effects on Hemodynamic and Respiratory Parameters

Background: Laparoscopic cholecystectomy is a minimally invasive surgical technique for amputation of anunhealthy gallbladder. This procedure has several advantages including shorter stay in hospital, minimal postoperativepain and fast recovery after procedure. The disadvantages of this procedure due to increase intraabdominalpressure, patient position and general anesthesia. Many of anesthetist apply VCV in this procedure.VCV can deliver adequate minute volume but this is corresponded by an increase in airway pressure, so otheralternative mode can be used to solve this problem like PCV.Aim of the Study: To compare effect of volume controlled ventilation versus pressure controlled ventilation onrespiratory and haemodynamic parameters during laproscopic cholycystectomy.Patients and method: A prospective comparative observational study, conducted at the Department of generalsurgery in Baghdad Teaching Hospital/Medical city complex, from October 2019 - October 2020. Fifty participantsunderwent laparoscopic cholecystectomy within the inclusion criteria were included in the present study. Eachgroup consist of 25 patients .one group received VCV and others receive PCV. peak airway pressure, mean airwaypressure, MAP, and heart rate was recorded intraoperatively at 5,10 and 30 minute intervals. The collected datawere analyzed by SSPS version 22 program.Results: In pressure control group of patients, the peak airway pressure was significantly deceased after 10 and30minutes after start of laparoscopy (20.2and 20.8) versus (24.3 and 24.1) respectively and mean airway pressurewas significantly increased after same time (10.6 and10.6) versus (9.7 and 9.7) respectively relative to volumecontrol group. No significant change in hemodynamic parameters. Conclusion: PCV mode is a safe alternative &offers protection to the lungs but there was no beneficial effect of PCV regarding mean airway pressures whichreflect oxygenation, minute ventilation &ETCO2.

Evaluation of time constant, dead space and compliance to determine PEEP in COVID-19 ARDS: a prospective observational study

Multiple variables exist to identify optimal positive end-expiratory pressure (PEEP) to keep alveolar recruitment in acute respiratory distress syndrome (ARDS). These include increased respiratory system compliance (CRS ) and decreased dead space to tidal volume fraction (Vd/Vt). Increasing CRS reflects improved lung volume, whereas decreasing Vd/Vt reflects improved ventilation/perfusion matching. An increasing expiratory time constant (RCEXP ) reflects both, changes in CRS and alterations in tissue resistance. Whether RCEXP might reflect corresponding changes in Vd/Vt better than CRS during alveolar recruitment is unknown. This prospective observational study examined the correlation between these variables during ascending PEEP titration in patients with novel Coronavirus disease (COVID-19) related ARDS. PEEP titrations were performed in ten patients with COVID-19 ARDS under passive, pressure-controlled ventilation with a fixed driving pressure of 14 cmH2O. PEEP was increased stepwise between 5 and 20 cmH2O with 2 minutes allowed for Vd/Vt equilibration. RCEXP , Vd/Vt and CRS were recorded at each PEEP level and statistically assessed.The overall correlation between Vd/Vt and RCEXP was −0.72 (95% CI: −0.57 to −0.82); p < 0.0001. CRS had a weaker correlation with Vd/Vt (−0.47 (95% CI: −0.25 to −0.64); p < 0.0001). RCEXP was the highest at 12 cmH2O of PEEP whereas Vd/Vt was the lowest at 10 cmH2O of PEEP and CRS was the highest at PEEP of 15 cmH2O.Both parameters of exhalation, Vd/Vt and RCEXP, are strongly correlated which likely reflects corresponding mechanical and global ventilation/perfusion responses during ascending PEEP titration.

Haptic Assistive Control With Learning-Based Driver Intent Recognition for Semi-Autonomous Vehicles

Semi-autonomous vehicles equipped with assistive control systems may experience degraded lateral behaviors when aggressive driver steering commands compete with high levels of autonomy. This challenge can be mitigated with effective operator intent recognition, which can configure automated systems in context-specific situations where the driver intends to perform a steering maneuver. In this article, an ensemble learning-based driver intent recognition strategy has been developed. A nonlinear model predictive control algorithm has been designed and implemented to generate haptic feedback for lateral vehicle guidance, assisting the drivers in accomplishing their intended action. To validate the framework, operator-in-the-loop testing with 30 human subjects was conducted on a steer-by-wire platform with a virtual reality driving environment. The roadway scenarios included lane change, obstacle avoidance, intersection turns, and highway exit. The automated system with learning-based driver intent recognition was compared to both the automated system with a finite state machine-based driver intent estimator and the automated system without any driver intent prediction for all driving events. Test results demonstrate that semi-autonomous vehicle performance can be enhanced by up to 74.1% with a learning-based intent predictor. Further, the learning-based model has a 30.9% higher driver intent recognition accuracy than the finite state machine-based method. The holistic framework that integrates human intelligence, machine learning algorithms, and vehicle control can help solve the driver-system conflict problem leading to safer operation.

Safety Assist Control for Nonautonomous Control-affine Systems via Time-varying Control Barrier Function

The recent research on nonlinear control systems tends to prioritize safety beyond stability, and control barrier functions (CBFs) have been gaining popularity as a CBF-based controller can theoretically ensure safety of control systems with the notion of set invariance. In this paper, we define a time-varying CBF (Tv-CBF) for a nonautonomous control-affine system with a human operator input to address a time-dependent safety constraint problem. Then, we propose a human assist control law using a Tv-CBF that satisfies time-dependent safety constraints. We also prove that solutions to an ordinary differential equation denoting control systems are forward complete by employing the proposed human assist controller. Lastly, the effectiveness of the proposed method is confirmed through computer simulation.

Aortic valve replacement, coronary artery bypass grafting and carotid endarterectomy under continuous coronary perfusion, cardiopulmonary bypass and mechanical ventilation in a patient with heart failure and reduced left ventricular ejection fraction

Aortic valve replacement, coronary artery bypass grafting and carotid endarterectomy under continuous coronary perfusion, cardiopulmonary bypass and mechanical ventilation in a patient with heart failure and reduced left ventricular ejection fraction

NONINVASIVE MECHANICAL VENTILATION IN COVID-19 RELATED ACUTE RESPIRATORY FAILURE.

Coronavirus disease 2019 (COVID-19) is presented with a wide range of symptoms, from asymptomatic disease to severe and progressive interstitial pneumonia. As part of interstitial pneumonia, respiratory failure is typically presented as hypoxia and is the most common cause of hospitalization. When oxygen therapy fails, continuous positive airway pressure (CPAP) or noninvasive mechanical ventilation (NIV) are used as respiratory support measures of first choice. Noninvasive respiratory support (NIRS) is applied in order to save intensive care unit resources and to avoid complications related to invasive mechanical ventilation. Emerging evidence has shown that the use of CPAP or NIV in the management of acute hypoxemic respiratory failure in COVID-19 reduces the need for intubation and mortality. The advantage of NIRS is the feasibility of its application on wards. NIV could be administered via a face mask or helmet interface. Helmet adheres better than mask and therefore leakage is reduced, a delivery of positive end-expiratory pressure is more accurate, and the risk of nosocomial transmission of infections is lowered. Patients on NIRS must be carefully monitored so that further respiratory deterioration is not overlooked and additional measures of care including timely intubation and invasive mechanical ventilation could be performed if needed.

Severe lactic acidosis after re-exposure to linezolid in a person living with HIV and multidrug resistant tuberculosis: a case report

Abstract Linezolid-induced lactic acidosis is rare and portends a poor prognosis. The mechanism of toxicity may be related to inhibition of mitochondrial ribosomes. We present the first case in the literature of a patient with HIV and multidrug resistant tuberculosis with fatal lactic acidosis secondary to linezolid re-exposure. The index case relates to a 37-year-old lady with a background medical history of HIV, on fixed combination antiretroviral therapy. In addition, she had multidrug resistant pulmonary tuberculosis and was being treated on a salvage antituberculosis regimen containing linezolid. She presented with a 1-day history of backpain, nausea and vomiting. Clinically she was severely acidotic with a lactate of 12 mmol/L, which peaked at 19 mmol/L. A presumptive diagnosis of lactic acidosis was made based on the history and exclusion of other causes. The patient demised despite management in the intensive care unit with continuous veno-venous haemodialysis (CVVH) and mechanical ventilation. The diagnosis of linezolid-induced lactic acidosis requires a high index of suspicion and exclusion of other causes. In the absence of definitive treatment, early diagnosis, drug discontinuation and prompt supportive management including continuous veno-venous haemodiafiltration are key in helping to reduce the high mortality associated with this toxicity.

Clinico-epidemiological Characteristics and Short-term Outcomes of Neonates Born to COVID-19 Positive Mothers at a Tertiary Care Hospital in North Karnataka- A Retrospective Study

Introduction: Coronavirus Disease-2019 (COVID-19) infection in pregnant women can have important effects on the perinatal and neonatal outcomes. Multiple modes of transmission of infection from mother to the newborn have been suggested as also the increased risk of complications in COVID-19 infected neonates. Aim: To study the clinico-epidemiological characteristics and short-term outcomes of neonates born to mothers infected with COVID-19 in relation to maternal COVID-19 severity and co-morbidities and to compare the same between COVID-19 infected and non infected neonates. Materials and Methods: This was a retrospective study of 174 neonates born to COVID-19 positive mothers admitted and delivered from 1st August 2020 to 31st October 2020, at Belagavi Institute of Medical Sciences (BIMS), North Karnataka, India. Data was collected from medical records about the clinical and epidemiological characteristics of the mothers and their neonates, symptoms and severity of COVID-19 and their management and short-term outcomes. Pearson’s Chi-square or Fisher’s-exact test was used for statistical analysis. The p-value of less than 0.05 was considered statistically significant. Results: Out of 174, 18 (10.35%) neonates tested positive for COVID-19 by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). The rates of pre-maturity and low birth weight amongst all 174 neonates were 17.24% and 24.14%, respectively. There were no significant differences in demographic features, in the need for resuscitation and incidence of complications like prematurity, low birth weight, birth asphyxia, meconium aspiration syndrome, sepsis between COVID-19 infected and non infected neonates. However, an increased risk of Early Onset Sepsis (EOS) (OR– 2.21) in COVID-19 infected neonates. None of the COVID- 19 infected neonates required Continuous Positive Airway Pressure (CPAP) or mechanical ventilation and all were discharged subsequently. In this study there were 3(1.72%) deaths, all among COVID-19 non infected, neonates. Conclusion: The incidence of COVID-19 infection in neonates born to COVID-19 infected mothers in this study was 10.35%. Most of the infections in neonates were of less severity without a significantly increased need for respiratory support and without significant mortality.

Iterative Range and Road Parameters Estimation Using Monocular Camera on Highways

Lane Keeping Assistance and Adaptive Cruise Control in Advanced Driving Assistance Systems (ADAS) requires road parameters for better control of the vehicle. Therefore, in this paper we present the Iterative Least Squares with Optimization (ILSO) method based on a monocular front camera which estimates the horizontal, vertical parameters, lateral slope and the camera’s distances to the left/right line as road parameters and longitudinal range. The ILSO algorithm is smartly divided into two steps LS and optimization depending on their estimation capabilities. First of all, the horizontal and vertical parameters, lateral slope, and distances to the left and right lines are estimated by Least Squares (LS). Then, the longitudinal range is estimated by convex optimization. LS and convex optimization are executed in an alternating manner. ILSO is in advance prior to changes on roads and a simple technique due to its analytical solution which does not require complex geometric calculations and does not need a match between left and right lines. In a simulation environment, given the noisy road lines, ILSO outperforms covariance based and multilayer perceptron (MLP) based methods under different noise variances. In addition, ILSO provides plausible numerical results in both virtual and real road images.

Assistive Path Control System for Blind and Deaf people with Visual and Depth perception Challenge

Assistive Path Control System for Blind and Deaf people with Visual and Depth perception Challenge

The Effect of Switching from Volume-Controlled to Pressure-Controlled Ventilation on Respiratory Distress and Asynchrony Index Improvement among Mechanically Ventilated Adults.

It is important to synchrony the time, intensity, and respiratory signal of the phrenic nerve between the patient and the ventilator. This study aimed to evaluate the effect of switching from volume-controlled to pressure-controlled ventilation on respiratory distress and asynchrony index improvement. In this randomized controlled clinical trial, 70 patients admitted to the intensive care unit under mechanical ventilation were included. Asynchronous evaluation was performed by examining the patient and evaluating and analyzing the graphic flow curve and ventilator pressure, which included trigger and flow asynchronous and asynchronous cycling. In the intervention group, the mode of ventilation was switched to PSIMV such that peak inspiratory pressures would be equivalent to positive end-expiratory pressure (PEEP) in the volume-controlled mode. Finally, again at 60, 75, and 90 min, information about the ventilator and the patient's symptoms, and arterial carbon dioxide levels were sent by arterial gas sample. The asynchronous index was also recorded in both groups. This study showed that the mean of variables such as height, ideal body weight, tidal volume, set rate; Sense, FiO2, PEEP did not differ significantly between the two groups. The mean of asynchrony was significantly reduced in both control group (16.51 ± 3.35-14.51 ± 2.90; P < 0.001) and intervention group (18.26 ± 6.13-13.32 ± 5.53; P < 0.001). Regardless of the type and severity of the disease, switching the ventilation mode from volume-controlled to pressure-controlled can improve patient adaptation to the ventilator, especially in cases with frequent asynchrony.

A Versatile Embedded Platform for Implementation of Biocooperative Control in Upper-Limb Neuromotor Rehabilitation Scenarios

Biocooperative control uses both biomechanical and physiological information of the user to achieve a reliable human-robot interaction. In the context of neuromotor rehabilitation, such control can enhance rehabilitation experience and outcomes. However, the high cost and large volume of the commercial systems for physiological signal acquisition are major limitations for the development of such control. We present a highly versatile, low-cost and wearable embedded system that integrates the most commonly used sensors in this field: inertial measurement unit (IMU), electrocardiography (ECG), electromyography (EMG), galvanic skin response (GSR) and skin temperature (SKT) sensors. Additionally, the compact system combines wireless communication for data transmission and a high-efficiency microcontroller for real-time signal processing and control. We tested the system in two common neuromotor rehabilitation scenarios. The first is an upper-limb rehabilitation VR-based exergame, in which the patient must collect as many coins as possible. Movement recognition of the hand and arm is performed based on EMG and IMU information, respectively. The second is adaptive assistive control that adjusts the level of assistance of a wrist rehabilitation robot according to the physiological state and motor performance of the patient using GSR, ECG and SKT data. The quality of the recorded signals and the processing capacity of the system meet the needs of the two upper-limb rehabilitation applications. The wearable system is highly versatile, open, configurable and low cost, and it could promote the development of real-time biocooperative control for a wide range of neuromotor rehabilitation applications.

Biochemical Substances and the Realm of S. 3(d) (Novozymes vs The Assistant Controller of Patents and Designs): Scope of Applicability of Section 3(d) Redefined by Madras High Court?

Biochemical Substances and the Realm of S. 3(d) (Novozymes vs The Assistant Controller of Patents and Designs): Scope of Applicability of Section 3(d) Redefined by Madras High Court?

Trajectory Tracking Strategy for Sliding Mode Control With Double Closed-Loop for Lawn Mowing Robot Based on ESO

The mowing robots work with a multivariable strong coupling underactuated system that is mostly troubled by difficulty controlling and unsatisfactory accuracy. Especially, the frequent external disturbances and parameter changes are likely to get missed and heavy cutting. In this paper, a new trajectory tracking control method based on extended state observer (ESO) is introduced with a particular focus on dual closed-loop sliding mode. Firstly, from the perspective of kinematics, a speed assistant controller was designed to generate the speed control quantity, and secondly, a sliding mode control algorithm based on the improved Fractional Power Rate Reaching Law (IFPRRL) was programmed to control the drive motor that tracked the speed control quantity. By means of comparison, our improved algorithm presented faster arrival time and better robustness along with similar jittering. At the same time, the robustness of the system was further enhanced with the help of an optimized ESO to tackle unmodeled disturbances and uncertain disturbances during the operation. Finally, the experimental analysis of the motor drive circuit and the trajectory tracking control system of the lawn mowing robot were both carried out respectively. The analysis shows that the performance of the proposed reaching law sliding mode control algorithm had some new pleasing changes, such as adjustment time and robustness. The circular trajectory and the detour mowing trajectory were respectively tracked in the double closed-loop sliding mode designed in this paper. The experimental goal was to ensure that the error vector <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{e} =$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> Axis position error <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x_{e}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> Axis position error <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y_{e}$ </tex-math></inline-formula> , Angle error <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta _{e}$ </tex-math></inline-formula> ) all remaining at (0.01m, 0.01m, 0.01rad) were 5.34s and 5.36s, respectively, and both could be finally converged to 0. The results show that the newly developed controller based on ESO presented smaller arrival time and stronger robustness. The dual-closed-loop control of sliding-mode trajectory tracking method was capable to meet the real-time and precision requirements of the lawnmower robot for quick trajectory tracking.

The ultrasound estimation of extravascular lung water in volume controlled versus pressure controlled ventilation after one lung ventilation in Thoracoscopic surgery. A-comparative study

ABSTRACT Background Thoracoscopic surgeries are an absolute indication of one lung ventilation OLV, the choice of using volume-controlled ventilation (VCV) or pressure controlled ventilation (PCV) remains controversial. Respiratory complications are major cause of postoperative morbidity which is associated with increased extravascular lung water (EVLW). Assessment of (EVLW) helps in early detection and treatment of respiratory complications. Lung ultrasound (LUS) has been suggested as reliable method of assessment of EVLW. This study was designed to figure out whether there was any difference in OLV by either PCV or VCV on EVLW water in the ventilated lung using LUS score and arterial oxygenation. Methodology 50 patients were randomly assigned into two groups; Group V: received VCV (Vt 7 ml/kg ideal body weight) Group P: received PCV (To achieve Vt 7 ml/kg ideal body weight, Pmax 30 cmh2o) Results We found that both techniques PCV and VCV showed no statistically significant differences as regards the ultrasound score at different timings of measurement; (T0) before induction of anesthesia, (T5) immediately at the end of operation after extubation, and (T6) 2 hours after ICU admission. Where P values were 0.525, 0.309, and 0.597 consecutively, we also found there were no statistically significant differences between the two groups regarding hemodynamics, arterial blood gases, ventilatory parameters. Conclusion We concluded that when utilizing VCV & PCV in OLV in thoracospic surgeries there was no statistically significant difference regarding EVLW score measured by LUS in the ventilated lung.

Comparison of Effects of Volume-Controlled and Pressure-Controlled Ventilation during Laparoscopic Surgeries in Birat Medical College Teaching Hospital

Introduction: The pneumoperitoneum created during laparoscopic surgery has numerous effects on the patient ranging from respiratory to hemodynamics. The two common methods of ventilator are volume control and pressure control. The volume control method has been commonly used during general anesthesia. Pressure control method has been used in intensive care unit for improving the respiratory mechanics.&#x0D; Objective: The study aims to compare the effects of pressure control to volume control ventilation in patients undergoing laparoscopic surgery. The hypothesis of the study is that pressure control method improves the respiratory mechanics by decreasing the peak airway pressure and increasing the lung compliance.&#x0D; Methodology: The total of 100 patients who underwent laparoscopic surgery were undertaken for this study. The 50 in each group (PCV and VCV) were allotted randomly. As per predicted body weight, the tidal volume was adjusted to 8 ml/kg, for both the modes of ventilation, peep 5 mm of Hg with fio2 of 100% and I:E-1:2,. The variations in peak airway pressure, mean airway pressure, lung compliance, SPO2 and hemodynamic parameters were observed at baseline (T1), at pneumoperitoneum (T2), after 10 minutes of pneumoperitonium (T3) and at 20 minutes after pneumoperitonium (T4).&#x0D; Results: The pressure control group on comparison to volume control mode group showed significant decrease in peak airway pressure while increase in mean airway pressure and increase in lung compliance at different points of pneumoperitoneum. However there was no significant change in hemodynamics between the two groups in patient undergoing laparoscopic surgery.&#x0D; Conclusion: We conclude that respiratory mechanics improve when the patient is on pressure control ventilation in compared to volume control method of ventilation. Whereas there is no difference in hemodynamic parameters between the two methods.&#x0D;

A new method of ventilation inhomogeneity assessment based on a simulation study using clinical data on congenital diaphragmatic hernia cases

Congenital Diaphragmatic Hernia (CDH) is a diaphragm defect associated with lung hypoplasia and ventilation inhomogeneity (VI). The affected neonates are usually born with respiratory failure and require mechanical ventilation after birth. However, significant interindividual VI differences make ventilation difficult. So far, there are no clinical methods of VI assessment that could be applied to optimize ventilation at the bedside. A new VI index is a ratio of time constants T1/T2 of gas flows in both lungs. Pressure-controlled ventilation simulations were conducted using an infant hybrid (numerical-physical) respiratory simulator connected to a ventilator. The parameters of the respiratory system model and ventilator settings were based on retrospective clinical data taken from three neonates (2, 2.6, 3.6 kg) treated in the Paediatric Teaching Clinical Hospital of the Medical University of Warsaw. We searched for relationships between respiratory system impedance (Z) and ventilation parameters: work of breathing (WOB), peak inspiratory pressure (PIP), and mean airway pressure (MAP). The study showed the increased VI described by the T1/T2 index value highly correlated with elevated Z, WOB, PIP and MAP (0.8–0.9, the Spearman correlation coefficients were significant at P < 0.001). It indicates that the T1/T2 index may help to improve the ventilation therapy of CDH neonates.