Driving pressure in mechanical ventilation:A review

Driving pressure(ΔP)is a core therapeutic component of mechanical ventilation(MV).Varying levels ofΔP have been employed during MV depending on the type of underlying pathology and severity of injury.However,ΔP levels have also been shown to closely impact hard endpoints such as mortality.Considering this,conducting an in-depth review ofΔP as a unique,outcome-impacting therapeutic modality is extremely important.There is a need to understand the subtleties involved in making sureΔP levels are optimized to enhance outcomes and minimize harm.We performed this narrative review to further explore the various uses ofΔP,the different parameters that can affect its use,and how outcomes vary in different patient populations at different pressure levels.To better utilizeΔP in MV-requiring patients,additional large-scale clinical studies are needed.

Driving pressure:A useful tool for reducing postoperative pulmonary complications

The operating room is a unique environment where surgery exposes patients to non-physiological changes that can compromise lung mechanics.Therefore,raising clinicians’awareness of the potential risk of ventilator-induced lung injury(VILI)is mandatory.Driving pressure is a useful tool for reducing lung complications in patients with acute respiratory distress syndrome and those undergoing elective surgery.Driving pressure has been most extensively studied in the context of single-lung ventilation during thoracic surgery.However,the awareness of association of VILI risk and patient positioning(prone,beach-chair,parkbench)and type of surgery must be raised.

Driving pressure decoded:Precision strategies in adult respiratory distress syndrome management

Mechanical ventilation(MV)is an important strategy for improving the survival of patients with respiratory failure.However,MV is associated with aggravation of lung injury,with ventilator-induced lung injury(VILI)becoming a major concern.Thus,ventilation protection strategies have been developed to minimize complications from MV,with the goal of relieving excessive breathing workload,improving gas exchange,and minimizing VILI.By opting for lower tidal volumes,clinicians seek to strike a balance between providing adequate ventilation to support gas exchange and preventing overdistension of the alveoli,which can contribute to lung injury.Additionally,other factors play a role in optimizing lung protection during MV,including adequate positive end-expiratory pressure levels,to maintain alveolar recruitment and prevent atelectasis as well as careful consideration of plateau pressures to avoid excessive stress on the lung parenchyma.

Spectral Analysis of Blood Pressure Variability as a Quantitative Indicator of Driving Fatigue

The quantitative detector of driver fatigue presents appropriate warnings and helps to prevent traffic accidents.The aim of this study was to quantifiably evaluate driver mental fatigue using the power spectral analysis of the blood pressure variability (BPV) and subjective evaluation. In this experiment twenty healthy male subjects were required to perform a driving simulator task for 3-hours. The physiological variables for evaluating driver mental fatigue were spectral values of blood pressure variability (BPV)including very low frequency (VLF), low frequency (LF),high frequency (HF). As a result, LF, HF and LF/HF showed high correlations with driver mental fatigue but not found in VLF. The findings represent a possible utility of BPV spectral analysis in quantitatively evaluating driver mental fatigue.

Predictive performance of the variation rate of the driving pressure on the outcome of invasive mechanical ventilation in patients with acute respiratory distress syndrome

Purpose:To assess the value of the driving pressure variation rate(ΔP%)in predicting the outcome of weaning from invasive mechanical ventilation in patients with acute respiratory distress syndrome.Methods:In this case-control study,a total of 35 patients with moderate-severe acute respiratory distress syndrome were admitted to the intensive care unit between January 2022 and December 2022 and received invasive mechanical ventilation for at least 48 h were enrolled.Patients were divided into successful weaning group and failed weaning group depending on whether they could be removed from ventilator support within 14 days.Outcome measures including driving pressure,PaO2:FiO2,and positive end-expiratory pressure,etc.were assessed every 24 h from day 0 to day 14 until successful weaning was achieved.The measurement data of non-normal distribution were presented as median(Q1,Q3),and the differences between groups were compared by Wilcoxon rank sum test.And categorical data use the Chi-square test or Fisher's exact test to compare.The predictive value ofΔP%in predicting the outcome of weaning from the ventilator was analyzed using receiver operating characteristic curves.Results:Of the total 35 patients included in the study,17 were successful vs.18 failed in weaning from a ventilator after 14 days of mechanical ventilation.The cut-off values of the medianΔP%measured by Operator 1 vs.Operator 2 in the first 4 days were≥4.17%and 4.55%,respectively(p<0.001),with the area under curve of 0.804(sensitivity of 88.2%,specificity of 64.7%)and 0.770(sensitivity of 88.2%,specificity of 64.7%),respectively.There was a significant difference in mechanical ventilation duration between the successful weaning group and the failure weaning group(8(6,13)vs.12(7.5,17.3),p=0.043).The incidence of ventilator-associated pneumonia in the successful weaning group was significantly lower than in the failed weaning group(0.2‰vs.2.3‰,p=0.001).There was a significant difference noted between these 2 groups in the 28-day mortality(11.8%vs.66.7%,p=0.003).Conclusion:The medianΔP%in the first 4 days of mechanical ventilation showed good predictive performance in predicting the outcome of weaning from mechanical ventilation within 14 days.Further study is needed to confirm this finding.

MATHEMATICAL MODEL OF ~4He QUANTUM INTERFEROMETER GYROSCOPE

The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- scope system. The driven equation shows the thermally driven gyroscope can work for a long time but the pres- sure driven one cannot. From the current equation, the superfluid currents passing through the weak link contain the AC currents which show the rotation flux, and other currents caused by drive. As shown in the position equa- tion, the displacement of diaphragm is the only detectable parameter in the gyroscope system. The model is tested by the simulations based on experimental parameters, and can be used to research performance of the gyroscope and analyse the gyroscope error.

Application of adaptive pressure-driven microfluidic chip in thyroid function measurement

The improvement in accuracy of in vitro diagnosis has always been the focus of early screening of thyroid dysfunction.We constructed a microfluidic chip based on a polystyrene polymer substrate.Total triiodothyronine(TT3),total thyroxine(TT4),free triiodothyronine(FT3),free thyroxine(FT4),and thyrotropin(TSH) in human whole blood samples were analysed by fluorescence immunoassay to evaluate thyroid function.The results indicate that the microfluidic chip shows a good linear relationship in the detection of TT3,TT4,FT3,FT4,and TS H standards,and the correlation coefficient(r) is not less than0.9900.In addition,the chip also has strong anti-interference(RSD%≤5%) and good repeatability(CV≤8%),and its inter-batch differences are small(CV ≤15%).The results of practical application in clinical thyroid function mea surement indicated its high accuracy(r≥0.9900).It provides a new method for the determination of thyroid function and lays a foundation for subsequent clinical application.

Difficulties and measures of driving super long piles in Bohai Gulf

Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element （FE） analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon.

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

Background Extracorporeal 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.Methods To 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.Results CRS 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.Conclusions Decreased 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.