Pressure Product Research Articles

Tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism.

Coordination among lip, cheek and tongue movements during swallowing in patients with mandibular prognathism remains unclear. This study aimed to identify the temporal sequences of tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism and compared characteristics with those of healthy volunteers. Seven patients with mandibular prognathism (mandibular prognathism group) and 25 healthy volunteers with individual normal occlusion (control group) were recruited. Tongue pressures and masseter, orbicularis oris, mentalis and supra- and infrahyoid muscle activities while swallowing gel were measured simultaneously using a sensor sheet system with five measurement points and surface electromyography, respectively. Onset time, offset time and durations of tongue pressure and muscle activities were analysed. In the mandibular prognathism group, tongue pressure was often produced first in more peripheral parts of the palate. Offset of tongue pressure in the posteromedian and peripheral parts of the palate and maxillofacial muscle activities except for orbicularis oris were delayed. Duration of tongue pressure in the anteromedian part of the palate was significantly shorter and durations of masseter, mentalis and suprahyoid muscle activities were significantly longer. Times to onset of orbicularis oris and suprahyoid muscle activities based on first onset of tongue pressure were significantly shorter. These results suggest that patients with mandibular prognathism may exhibit specific patterns of tongue pressure production and maxillofacial muscle activities during swallowing.

Role of catalyst topology in methanol synthesis

AbstractMethanol synthesis is carried out in a catalytic, packed bed reactor, where the shape and size of catalyst play a critical role in dictating overall reactor performance. In the current study, the effect of five different catalyst shapes including cylindrical, ring, trilobe, wagon wheel, and spherical on the reactor performance was investigated by conducting particle‐scale computational fluid dynamics (CFD) simulations. The predictions of pressure drop, velocity, temperature, reactant distribution and product yield were analyzed. When the performance of the simulated shapes was compared at the same tube Reynolds number of 50,000, internally contoured shapes (wagon wheel and ring) resulted in 40% higher pressure drops due to the tortuous flow path. However, the shape with internal void provided access for the reactant to reach the internal part of catalyst, resulting in higher yield produced per volume of catalyst. The wagon wheel shape produced 15% and 5% more yield per volume against the cylindrical shape and trilobe, respectively. The performance of the wagon wheel can be attributed to the lower diffusion limitation due to higher surface area available for reactant to penetrate the internal part of the catalyst.

Hemodynamic Reactivity to Mental Stress and Cognitive Function in Coronary Artery Disease.

People with coronary artery disease (CAD) are at higher risk of cognitive impairment than those without CAD. Psychological stress is a risk factor for both conditions, and assessing the hemodynamic reactivity to mental stress could explain the link between stress and cognitive function. A total of 779 individuals with stable CAD from two prospective cohort studies were included. All individuals underwent acute mental stress testing, as well as conventional stress testing. Cognitive function was assessed both at baseline and at a 2-year follow-up. The rate-pressure product (RPP) was calculated as the mean systolic blood pressure times the mean heart rate at rest. RPP reactivity was defined as the maximum RPP during standardized mental stress test minus the RPP at rest. After multivariable adjustment, every standard deviation decrease in RPP reactivity with mental stress was associated with slower completion of Trail-A and Trail-B in both cohorts (13% and 11% in cohort 1, and 15% and 16% in cohort 2, respectively; p for all <.01). After a 2-year follow-up period, every standard deviation decrease in RPP reactivity with mental stress was associated with a 8% and 9% slower completion of Trail-A and Trail-B, respectively ( p for all <.01). There was no significant association between RPP reactivity with conventional stress testing and any of the cognitive tests. In the CAD population, a blunted hemodynamic response to mental stress is associated with slower visuomotor processing and worse executive function at baseline and with greater decline in these abilities over time.

Design of Intelligent Control Systems for Layered Water Injections in Oilfields

With rapid socio-economic growth and increased energy demand, exploration and exploitation of oil and gas resources have become crucial. Long-term exploitation leads to problems such as pressure drop and production reduction in oil fields, and water injection technology has become a common method to improve these problems. The traditional direct water injection for oil extraction has problems such as high injection cost and low oil recovery efficiency. Therefore, an intelligent control system for different oilfield reservoirs is needed. This study focuses on the layered water injection intelligent system based on advanced sensor technology, digital signal processing and intelligent algorithms. The article reviews the advantages of layered water injection system and the current research status, designs an intelligent control structure including hardware circuits and modular software processes, and adopts adaptive particle swarm optimization algorithm as the core of intelligent control.

Absolute density measurement of hydrogen radicals in XUV induced plasma for tin contamination cleaning via laser-induced fluorescence

Effective cleaning of tin contamination on the collecting mirrors in extreme ultraviolet source is one of the key techniques to improve throughput and cost performance of extreme ultraviolet lithography. Hydrogen radicals produced in hydrogen plasma that is induced by wideband extreme ultraviolet radiation are expected to be utilized for in situ tin contamination cleaning in extreme ultraviolet sources. In this Letter, we clarified absolute density and cleaning ability of the hydrogen radicals produced by intense extreme ultraviolet pulse through ground state population density measurement by laser-induced fluorescence technique. The experimentally obtained radical parameters coincided well with simulation results and collisional radiative model. It was found that the extreme ultraviolet induced plasma was in quasi-steady state with abundant amount of hydrogen radicals in ground state. Further, it was found that the in situ tin contamination cleaning in extreme ultraviolet lithography source would become more practical with increase in operational parameters, such as extreme ultraviolet emission intensity, gas pressure, and radical production cross section.

Prognostic value of myocardial flow reserve vs corrected myocardial flow reserve in patients without obstructive coronary artery disease

BackgroundMyocardial flow reserve (MFR) by positron emission tomography (PET) is a validated measure of cardiovascular risk. Elevated resting rate pressure product (RPP = heart rate x systolic blood pressure) can cause high resting myocardial blood flow (MBF), resulting in reduced MFR despite normal/near-normal peak stress MBF. When resting MBF is high, it is not known if RPP-corrected MFR (MFRcorrected) helps reclassify CV risk. We aimed to study this question in patients without obstructive coronary artery disease (CAD). MethodsWe retrospectively studied patients referred for rest/stress cardiac PET at our center from 2006 to 2020. Patients with abnormal perfusion (summed stress score >3) or prior coronary artery bypass grafting (CABG) were excluded. MFRcorrected was defined as stress MBF/corrected rest MBF where corrected rest MBF = rest MBF x 10,000/RPP. The primary outcome was major cardiovascular events (MACE): cardiovascular death or myocardial infarction. Associations of MFR and MFRcorrected with MACE were assessed using unadjusted and adjusted Cox regression. Results3276 patients were followed for a median of 7 (IQR 3–12) years. 1685 patients (51%) had MFR <2.0, and of those 366 (22%) had an MFR ≥2.0 after RPP correction. MFR <2.0 was associated with an increased absolute risk of MACE (HR 2.24 [1.79–2.81], P < 0.0001). Among patients with MFR <2.0, the risk of MACE was not statistically different between patients with an MFRcorrected ≥2.0 compared with those with MFRcorrected <2.0 (1.9% vs 2.3% MACE/year, HR 0.84 [0.63–1.13], P = 0.26) even after adjustment for confounders (P = 0.66). ConclusionsIn patients without overt obstructive CAD and MFR< 2.0, there was no significant difference in cardiovascular risk between patients with discordant (≥2.0) and concordant (<2) MFR following RPP correction. This suggests that RPP-corrected MFR may not consistently provide accurate risk stratification in patients with normal perfusion and MFR <2.0. Stress MBF and uncorrected MFR should be reported to more reliably convey cardiovascular risk beyond perfusion results.

Well Shut-In Pressure Determination Method for Deepwater Drilling Considering Fluid-Solid-Heat Coupling

Blowout is one of the most serious safety threats in deepwater drilling. Considering the characteristics of gas invasion in complex formations, gas migration and distribution, and dynamic changes in temperature inside a wellbore, a deepwater well-closing pressure determination method considering thermal-fluid-solid coupling was proposed. The model was verified using actual data, and the average error in the increase in casing pressure during the closing process was found to be 5.42%. The shut-in pressure of oil and gas wells under a transient shut-in process was analyzed. The results showed that the fluid thermal expansion caused by temperature recovery had a significant impact on the change in wellhead backpressure after well closure. Furthermore, the time required for the wellbore pressure to recover to the formation pressure varies nonlinearly with factors such as geothermal gradients, pit gains, bottom-hole pressure, and gas production indices. A pressure calculation chart was developed for deepwater drilling. The shut-in time for deepwater drilling should not be less than 15 min, and in cases where the gas production index is small and the bottomhole pressure difference is large, the shut-in time should exceed 90 min. The results can provide theoretical guidance and technical support for well shut-in processes during deepwater drilling.

Ground effect of an inverted double element wing diffuser on a sedan car

The diffuser is a critical component in sports cars, enhancing aerodynamics by increasing downforce and reducing drag. Previous studies have focused on its dependence on diffuser incidence, height, and base pressure. The design of the car, particularly the rear end shape and the rear wing's presence, affect base pressure and the diffuser's performance. Previous studies have investigated the effects of diffuser geometry on aerodynamic performance, but the current study is the first to examine the relationship between the diffuser and the rear tires. It also provides specific and quantitative results on the impact of different diffuser design parameters on drag and downforce. The relationship between the rear tires and the double-element inverted wing diffuser using computational fluid dynamics (CFD) was investigated. This is an essential problem because the diffuser is a critical component of sports cars, and its design can significantly impact aerodynamic performance. CFD was used to simulate the flow of air around the car model. The CFD model was based on the Nissan Sunny (Versa) type Almera design, and the diffuser main element and flap wing angles were set at 4 and 15.5°, respectively. The flap gap, overlap distance, and wing ride height above the ground were varied to achieve an optimal aerodynamic design. The study found that the wing's ride height significantly influences the flow through the diffuser. The diffuser significantly impacts base pressure and downforce production. Increasing the ride height decreases base pressure, leading to an increase in downforce until a specific point near the car body, where downforce further increases. The study concluded that the best double-element diffuser design was selected based on lift-to-drag results and the allowable dimensions of the car, wing ride height, element gap, and overlap distances. Ultimately, the best diffuser wing design features a ride height of 154 mm, a gap distance of 10 mm, and an overlap of 5 mm. This design reduces drag by approximately 2.7 % and remarkably increases downforce ten times compared to the baseline car model.

Tongue pressure production and orofacial muscle activities during swallowing are related to palatal morphology in individuals with normal occlusion

ABSTRACT Purpose The relationships between motor function, including the orofacial muscles coordinated with the tongue during swallowing, and palatal morphology are still unclear. This study aimed to identify the relationships between tongue pressure production and orofacial muscle activities during swallowing and palatal morphology. Materials and methods The participants were 20 healthy volunteers with individual normal occlusion (8 men, 12 women; mean age: 25.0 ± 2.9 years). Tongue pressure and masseter, orbicularis oris, mentalis and supra-infrahyoid muscle activities during 4 ml gel swallowing were recorded simultaneously by a sensor sheet system, with five measuring points and surface electromyography, respectively. Onset, offset and duration of each parameter and the maximum magnitude of tongue pressure were analysed. Palatal width and depth were measured using three-dimensional digital images of maxillary dental models and examined for correlations with tongue pressure and orofacial muscle activities. Results The temporal coordination between tongue pressure production and orofacial muscle activities during swallowing was observed. The maximum magnitude of tongue pressure was significantly positively correlated with the palatal width. Palatal depth showed significant correlations with the time sequences of tongue pressure and orbicularis oris and mentalis muscle activities. Conclusion These results suggest that tongue pressure production and orofacial muscle activities during swallowing are related to palatal width and depth.

Upper limit estimate to wellhead flowing pressure and applicable gas production for a downhole throttling technique in high-pressure–high-temperature gas wells

In recent years, China has explored and exploited several high-pressure deep gas fields. Normally, high-pressure gas wells are gathered and processed through multichoke manifolds on well sites, creating hazards such as high wellhead flowing pressure (Pt) and high risk for on-site operation personnel. Moreover, downhole chokes have been used in place of surface chokes. In doing this, the Joule–Thomson (JT) effect is geothermally regulated, alleviating the formation of hydrates in surface facilities. However, its applicability to high-pressure gas wells is less explored. In an effort to guide its use, the objective of this study is to set selection criteria in terms of the allowable wellhead Pt and gas flow rate. First, isenthalpic lines are separately estimated for dry gas and high liquid hydrocarbon (LHC) content gas condensate at various inlet temperatures with the use of commercial software. Next, by analysis of the resulting isenthalpic curves, several results are obtained on the JT inversion curves and throttling process through a choke. Third, building on these insights, a method for projecting the maximum Pt is presented, leading to a value of 52.5 MPa. Finally, multiparameter models are separately run for two deep gas wells (8100 m and 5000 m), reinforcing the result of the pressure upper limit while maintaining a maximum daily gas production of 14 E4 m3. Both upper limits with a maximum Pt of 52.5 MPa and daily gas production of 14 E4 m3 are corroborated with field data records. These findings are vital to the selection of a viable high-pressure gas well for applying the downhole throttling technique.

Abstract MP64: Cardiovascular Responses to Occupational Physical Activity Are Exaggerated by Work-Related Stress and Low Fitness

Introduction: Proposed mechanisms explaining the link between high occupational physical activity (OPA) and cardiovascular disease hypothesize that high work-related stress and low worker fitness may exacerbate cardiovascular responses to OPA. Hypothesis: Direct associations between OPA and acute cardiovascular responses will be stronger under high work-related stress and in workers with lower fitness. Methods: 19 male workers (age=46.6±7.9, 68.4% White) with high OPA jobs were observed for seven days. Steps, light (LPA), and moderate-to-vigorous physical activity (MVPA) during work were measured using a thigh-worn activPAL3 micro, hip-worn Actigraph GT3X-BT, and time-use diary. Heart rate (HR) was measured continuously with a Polar chest strap. 24-hour blood pressure (BP) was measured using an ambulatory BP monitor on one workday. Rate-pressure product (RPP), an indirect measure of cardiac workload, was calculated as systolic BP x HR. Daily work-related stress was measured with the Stress in General Scale (scores=-3-21 where higher scores indicate more stress). Worker fitness was estimated as VO 2 max (ml·kg -1 ·min -1 ) using a submaximal treadmill test. Effect modification by stress and fitness on the associations between OPA and RPP was examined using mixed effects models with interaction terms. Results: Work-related stress was directly associated with 24-hour RPP (β=94.10 mmHg*bpm/stress point, p=0.024) while worker fitness was not (β=-33.0 mmHg*bpm/VO 2 max, p=0.561). Direct association between RPP and occupational MVPA were stronger with higher work-related stress and lower fitness (Table 1, p-for-interaction&lt;0.05 for all). Lower intensity OPA (steps and LPA) were also associated with exacerbated RPP responses outside of work with higher work-related stress (Table 1, p-for-interaction&lt;0.001 for all). Conclusions: OPA performed under high stress or by workers with low fitness may exaggerate cardiovascular responses and contribute to OPA's paradoxical cardiovascular health associations.

Evaluation of Recovery of Tight Sandstone Gas Reservoirs Based on a Seepage Steady-State Model

As an important indicator for measuring the effectiveness and level of oil and gas field development, recovery rate has always been a focus in the research of oil and gas fields. Reservoirs of tight sandstone gas formations have significant characteristics of low porosity, high permeability, and high water content, which leads to greater difficulty in their development and makes it challenging to evaluate the recovery rate. Newtonian mechanics, as an important component of the mechanical system, is an innovative application of classical mechanics in the field of seepage mechanics when applied to the two-phase flow of gas and water. Firstly, starting from the perspective of mechanics analysis, we derive a steady-state model for gas–water two-phase infiltration and obtain the productivity equation based on this model. Then, according to the steady-state model, we establish a method to calculate the effective control radius of gas reservoirs under different production conditions and reservoir physical properties. Finally, using Matlab 2018a programming based on the productivity equation, we calculate the gas recovery under different conditions during constant pressure drop production and constant production rate production. The results indicate that the effective control radius of the reservoir decreases with an increase in the economic ultimate daily gas production, increases with an increase in production pressure difference, slightly decreases with an increase in startup pressure gradient, and correspondingly increases with an increase in microtube radius and quantity. Regardless of whether it is production with a fixed pressure drop or production with a fixed production rate, the gas recovery decreases as the production pressure drop and bottomhole abandonment pressure increase, but it increases as the proportion of the single-well control radius increases. In production with a fixed pressure drop, the gas recovery remains consistent across different reservoir quality indices. However, in production with a fixed production rate, the gas recovery initially increases rapidly and then gradually slows down as the reservoir quality index increases, and there is an obvious critical permeability (0.1 mD). The research findings are based on the mechanical analysis of porous media, delving into the laws governing fluid flow during infiltration. The derived infiltration model can be used to calculate the effective control radius and evaluate recovery rates, providing practical guidance for reservoir development.

Experimental and numerical study on the high-speed gas-solid nozzle erosion of choke manifold material in high pressure and high production gas well

High pressure difference, high flow rate, and high sand content in throttling manifolds of high-pressure and high-production gas wells make the problems of high-speed gas-solid erosion wear especially prominent. The failure of the throttling manifold is frequent, which is easy to induce overflow, kick, and blowout accidents, aggravates well-controlled risks, and brings safety risks. Therefore, according to ASTM G76–2013, this paper adopts the gas-solid nozzle erosion test method and air jet erosion test rig. The high speed (107 m/s-49 m/s) gas-solid nozzle erosion test of 30CrMo alloy steel was carried out under different inlet pressures (0.06 MPa–0.15 MPa) and impact Angle (15°-90°), and the erosion rate of 30CrMo alloy steel under different experimental conditions was obtained. The erosion rate equation of 30CrMo alloy steel suitable for high-speed solid particle impact is established. Based on the results of erosion experiments, the optimal particle motion model for high-speed compressible flow is constructed. Combined with the discrete phase model (DPM) and gas-solid two-phase coupling calculation method, a three-dimensional CFD erosion model of the “reduced-tuber-nozzle-erosion cavity” was established. The erosion simulation of the gas-solid nozzle of 30CrMo alloy steel, a throttling manifold material, was carried out at different impact angles (15°-90°) and inlet pressure (0.06 MPa–0.15 MPa), and the distribution characteristics of the flow field, particle movement trajectory, impact velocity distribution, and slip characteristics were revealed. The accuracy and reliability of the CFD erosion model and simulation results have been validated by test data.

Effect of supervised exercise training on cardiovascular function in patients with intermittent claudication: a systematic review and meta-analysis of randomized controlled trials.

This study aimed to determine the effect of supervised exercise training (SET) on cardiovascular function in patients with intermittent claudication (IC). A systematic search in MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases was conducted. Primary outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), rate pressure product (RPP), cardiac output (CO), peak oxygen consumption (VO2peak), and heart rate variability (HRV). Secondary outcomes were maximum walking distance (MWD) and pain-free walking distance (PFWD). Outcomes were reported as weighted mean difference (WMD) between the SET group and the control group and synthesized by using the random-effects model. Seventeen RCTs with a total of 936 patients were included in this review. SET resulted in significant improvements of SBP (WMD = - 7.40, 95% CI - 10.69 ~ - 4.11, p < 0.001, I2 = 15.2%), DBP (WMD = - 1.92, 95% CI - 3.82 ~ - 0.02, p = 0.048, I2 = 0.0%), HR (WMD = - 3.38, 95% CI - 6.30 ~ - 0.46, p = 0.023, I2 = 0.0%), RPP (WMD = - 1072.82, 95% CI - 1977.05 ~ - 168.59, p = 0.020, I2 = 42.7%), and VO2peak with plantar flexion ergometer exercise (WMD = 5.57, 95% CI 1.66 ~ 9.49, p = 0.005, I2 = 62.4%), whereas CO and HRV remained statistically unaltered. SET also improved MWD (WMD = 139.04, 95% CI 48.64 ~ 229.44, p = 0.003, I2 = 79.3%) and PFWD (WMD = 40.02, 95% CI 23.85 ~ 56.18, p < 0.001, I2 = 0.0%). In conclusion, SET is effective in improving cardiovascular function in patients with IC, which was confirmed on outcomes of cardiovascular function associated with exercise ability. The findings hold out that the standard therapy of SET can improve not only walking distance but also cardiovascular function in patients with IC.

Changes in rate-pressure product associated with pregnancy

In nonpregnant individuals, the rate-pressure product, the product of heart rate and systolic blood pressure, is used as a noninvasive surrogate of myocardial O2 consumption during cardiac stress testing. Pregnancy is considered a physiological cardiovascular stress test. Evidence describing the impact of pregnancy on myocardial O2 demand, as assessed by the rate-pressure product, is limited. This study aimed to describe changes in the rate-pressure product for each pregnancy trimester, during labor and delivery, and the postpartum period among low-risk pregnancies. This was a retrospective cohort study that assessed uncomplicated pregnancies delivered vaginally at term. We collected rate-pressure product (heart rate × systolic blood pressure) values preconception, during pregnancy for each trimester (at ≤13 weeks + 6/7 days, at 14 weeks + 0/7 days through 27 weeks + 6/7 days, and at ≥28 weeks + 0/7 days), during the labor and delivery encounter (hospital admission until complete cervical dilation, complete cervical dilation until placental delivery, and after placental delivery until hospital discharge), and during the outpatient postpartum visit at 2 to 6 weeks after delivery. We calculated the percentage change at each time point from the preconception rate-pressure product (delta rate-pressure product). We used a mixed-linear model to analyze differences in the mean delta rate-pressure product over time and the influence of prepregnancy age, prepregnancy body mass index, and neuraxial anesthesia status during labor and delivery on these estimates. Our cohort comprised 316 patients. The mean rate-pressure product increased significantly from preconception starting at the third trimester of pregnancy and during labor and delivery (P≤.05). The mean delta rate-pressure product peaked at 12% and 38% in the third trimester and during labor and delivery, respectively. Prepregnancy body mass index was inversely correlated with the mean delta rate-pressure product changes (estimate, -0.308; 95% confidence interval, -0.536 to -0.80; P=.008). In contrast, neither the prepregnancy age, nor neuraxial anesthesia status during labor had a significant influence on this parameter. This study validates the transient but significant increase in the rate-pressure product, a clinical estimate of myocardial O2 demand, during uncomplicated pregnancies delivered vaginally at term. Pregnant individuals with lower prepregnancy body mass index experienced a sharper increase in this parameter. Patients who receive neuraxial anesthesia during labor and delivery experience similar changes in the rate-pressure product as those who did not.

Rate-Pressure Product is a Novel Predictor for Short- and Long-Term Mortality in Patients with Acute Coronary Syndrome Undergoing Primary PCI/Immediate Invasive Strategy.

Rate-pressure product (RPP) calculated by multiplying heart rate by systolic blood pressure, is a convenient indicator closely associated with cardiac work or myocardial oxygen consumption. It has been reported to relate strongly to important indices of cardiovascular risk in patients with myocardial ischemia. However, its relationship with short- and long-term mortality in patients with acute coronary syndrome (ACS) undergoing primary PCI/immediate invasive strategy has not been defined. This study analyzed 1301 consecutive ACS patients who had undergone primary PCI, between January 2018 and September 2021. Patients with systolic BP < 90 mmHg were excluded to avoid the confounding effect of cardiogenic shock. RPP values were collected on admission and were divided into four groups: RPP ≤ 7.4, 7.4 ≤ 8.8, 8.8 <8.8 < RPP8, and RPP > 10.8. Clinical endpoints were in-hospital cardiac and long-term all-cause mortality. The predictive performance was assessed by C-statistic, multivariate analysis and survival analysis. Multivariate analysis showed that these in the highest vs lowest category of RPP (>10.8 vs ≤7.4) had OR of 4.33 (95% CI=1.10 -17.01; P = 0.036) in in-hospital cardiac mortality and 3.15 (95% CI=1.24 -8.00; P = 0.016) in long-term all-cause mortality. In C-statistic analyses, RPP was a strong predictor in ACS, STEMI or UA/NSTEMI group for in-hospital cardiac mortality (AUC = 0.746, 95% CI = 0.722-0.770, p < 0.001) and long-term all-cause mortality (AUC = 0.701, 95% CI = 0.675-0.725, p < 0.001). The Kaplan-Meier event rate for long-term survival of RPP > 10.8 was significantly lower than that of RPP ≤ 10.8. RPP showed a positive association with in-hospital cardiac or long-term all-cause mortality in ACS patients undergoing primary PCI/immediate invasive strategy, and RPP > 10.8 can be as an independent predictor.

Comparative evaluation between oral gabapentin and oral pregabalin premedication for attenuation of hemodynamic surge to laryngoscopy and endotracheal intubation in elective procedures under general anesthesia

Background: Effective attenuation of the sympathetic surge due to laryngoscopy and endotracheal intubation is needed. We wanted to compare the role of oral gabapentin (600 mg) and oral pregabalin (150 mg) in controlling this sympathetic surge. Aims and Objectives: To compare the role of oral gabapentin (600 mg) and oral pregabalin (150 mg) as premedications for attenuating hemodynamic surge to laryngoscopy and endotracheal intubation. Materials and Methods: 90 patients aged 18–45 years with ASA grade I or II posted for elective surgical procedure under general anesthesia were randomly allocated to two equal groups (45 in each group) to receive either 600 mg oral gabapentin or 150 mg oral pregabalin 1 h prior to surgery. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and rate pressure product (RPP) were recorded after intubation at 1 (T1), 3 (T3), 5 (T5), and 10 (T10) min. Post-operative sedation and post-operative nausea and vomiting (PONV) were recorded and compared. Results: Gabapentin attenuates hemodynamic surge in terms of HR, SBP, DBP, MAP, and RPP better than pregabalin during laryngoscopy and endotracheal intubation at 3, 5, and 10 min after intubation, while there was no significant difference between the two groups at 1 min after intubation. Post-operative sedation score and adverse effects like PONV and SpO2 fluctuations at different points in time were comparable. Conclusion: Oral gabapentin (600 mg) was found to be more effective than oral pregabalin (150 mg) in attenuating the hemodynamic surge to laryngoscopy and intubation.

Temperature compensation for piezoresistive pressure sensor based on deep learning on graphs

With the escalating demand for precision in piezoresistive pressure sensors to cater to a wide spectrum of applications, a significant challenge emerges due to the material properties of these sensors, which induce a substantial temperature coefficient. This limitation restricts the operational temperature range and is further exacerbated by ambient temperature variations, resulting in pronounced nonlinearity in sensor responses. To address these challenges, A new method using Graph Neural Networks (GNNs) is introduced to address nonlinearity and temperature drift in piezoresistive pressure sensors. GNNs improve the sensors’ accuracy and reliability across different temperatures, expanding their applicability. Test results show a notable accuracy enhancement, with a maximum full-scale error below 0.05% and even lower in specific ranges (under 0.04%). This precision makes the method ideal for industrial pressure sensor applications and production, offering significant benefits.

Cardioprotective effects of losartan and diminazene against the ischemia/reperfusion injury in hyperthyroidism rats.

Hyperthyroidism is a condition where the thyroid gland produces high levels of thyroid hormone. Heart diseases are one of the main complications of hyperthyroidism. Several studies have shown that losartan (LOS) and diminazene aceturate (DIZE) possess cardioprotection effects against cardiac hypertrophy, ischemic heart disease, and heart failure. The research aimed to investigate the cardioprotection of LOS, DIZE, and their combination in the case of levothyroxine (LT4)-induced cardiomyopathy in rats. Hyperthyroidism was induced by LT4 in drinking water (12mg/L) for 28 days. LOS (10mg/kg, orally) and/or DIZE (15mg/kg, subcutaneously) were administrated in rats with hyperthyroidism for 28 days. Decreased serum creatine kinase myoglobin and lactate dehydrogenase levels and cardiac hypertrophy by DIZE and combination therapy in hyperthyroidism rats have been reported. Cardiac hemodynamic findings showed that DIZE and its combination with LOS decreased the LT4-mediated left ventricular developed pressure (LVDP), rate pressure product (RPP), and RPP recovery percentage. Elevated cardiac oxidative stress and inflammation were confirmed by decreasing cardiac superoxide dismutase (SOD) activity and increasing the total oxidative stress and tumor necrosis factor-alpha (TNF-α) levels. SOD activity and TNF-α level were reversed by LOS and DIZE administration, respectively. Generally, DIZE and combination therapy with LOS improved cardiac dysfunction caused by hyperthyroidism in rats, whereas LOS alone has not been able to effectively respond to this dysfunction.

Comparison of the Effects of Nitroglycerin, Labetalol and Lidocaine in Hypertensive Patients in Attenuation of the Endotracheal Intubation Reflex

Background: Laryngoscopy and tracheal intubation integral parts of general anesthesia which may cause acute haemodynamic instability. Hypertensive patients are more prone of developing cardiovascular complications such as pulmonary oedema, cardiac failure and cerebrovascular haemorrhage. To attenuate such intubation reflex, some drugs are used, e.g., opioids. lidocaine sodium nitroprusside, nitroglycerin, beta blockers, calcium channel blockers etc. Objective: The purpose of the study is to see the effectiveness of nitroglycerin, labetalol and lidocaine in attenuation of intubation reflex and their anesthetic outcome in hypertensive patients. Methods: This randomized controlled study was carried out in the Department of Anesthesia, Pain, Palliative and Intensive care Medicine, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh, between March and September of 2021. A total of 90 patients were included: 30 in each group as per inclusion and exclusion criteria. Group A patients received inj. nitroglycerin 2 minutes before intubation, while group B patients received inj. labetalol 0.25mg/kg 5 minutes before intubation, and group C was given 2% lidocaine 1.5mg/kg 2 minutes before intubation. Haemodynamic status of all patients was checked before and after intubation. Results: Mean age of the patients was 44.4±10.9 years in group A, 47.6±9.4 years in group B and 46.4±10.6 years in group C. Heart rate after intubation was low and statistically significant in groups-B after 1.2 and 5 minutes. Regarding mean arterial pressure (MAP), group A patients had significantly low blood pressure. Rate pressure product (RRP) of the patients was significantly low in group B at 1 minute, 2 minutes and 5 minutes. Regarding ECG changes sinus tachycardia was observed in 26.6%, 86.6% and 20% in group A, group B and group C immediately after intubation. Groups B patients showed lower incidence of sinus tachycardia than that of two other groups and showed no premature ventricular contractions, whereas group A (6.7%) and group C (3.3%) showed premature ventricular contractions. Conclusion: Labetalol showed better rhythm control, mean arterial pressure and less incidence of tachycardia. To summarize, labetalol is safer and more effective than nitroglycerin and lidocaine to attenuate the endotracheal intubation reflex in hypertensive patients. Mugda Med Coll J. 2023; 6(2): 64-70