Mars 2020 Perseverance Rover Studies of the Martian Atmosphere Over Jezero From Pressure Measurements

The pressure sensors on Mars rover Perseverance measure the pressure field in the Jezero crater on regular hourly basis starting in sol 15 after landing. The present study extends up to sol 460 encompassing the range of solar longitudes from L _s  ∼ 13°-241° (Martian Year (MY) 36). The data show the changing daily pressure cycle, the sol-to-sol seasonal evolution of the mean pressure field driven by the CO₂ sublimation and deposition cycle at the poles, the characterization of up to six components of the atmospheric tides and their relationship to dust content in the atmosphere. They also show the presence of wave disturbances with periods 2-5 sols, exploring their baroclinic nature, short period oscillations (mainly at night-time) in the range 8-24 min that we interpret as internal gravity waves, transient pressure drops with duration ∼1-150 s produced by vortices, and rapid turbulent fluctuations. We also analyze the effects on pressure measurements produced by a regional dust storm over Jezero at L _s  ∼ 155°.

Effect of the design of safety harness on the pressures exerted on the user's body in the state of its suspension

AbstractThe presented studies concern the pressure of safety harnesses on the user's body in a state of its suspension. An anthropomorphic dummy was used for simulation of human behaviour in suspension. The test objects included four models of the harnesses of different designs, equipped with attachment elements placed at the back and front of the human body. Pressure mapping sensors of 56 × 56 mm2 surface area and a 2D pressure mapping apparatus were used for the measurements. The parameters characterizing the pressures of the harness belts on the dummy surface were defined. The obtained results demonstrated in which position the pressures exerted on the dummy are the greatest and that they depend mainly on the design of the safety harnesses and their attachment point. The most sensitive points of action of the harness on the user's body have been identified. Guidelines for the construction of the safety harnesses have been formulated.

Are there sex-related differences in therapeutic CPAP levels in adults undergoing in-lab titration?

STUDY OBJECTIVES

The first-choice therapy for adults with moderate/severe obstructive sleep apnea (OSA) is continuous positive airway pressure (CPAP). However, studies evaluating whether the therapeutic CPAP level obtained from a titration is affected by sex are surprisingly scarce. Our main objective was to verify if sex influenced the optimal CPAP measurement obtained during a titration.

METHODS

This cross-sectional study was conducted in adults diagnosed with moderate/severe OSA (baseline apnea-hypopnea index [AHI] ≥ 15.0/h), who underwent auto-adjusting CPAP titration (S9 or S10 AutoSet ResMed) in a sleep-lab setting. All participants used a nasal mask during the titration. The optimal pressure, leak, and residual AHI values were registered. Multiple linear regression was used to evaluate if clinical and polysomnographic data influenced the therapeutic CPAP level setting (95^th percentile pressure).

RESULTS

A total of 1,006 adults were enrolled: 354 women and 652 men. There were no statistically significant sex-related differences in the CPAP requirements and leak values as delineated during the titration; all p-values > 0.005. However, the median residual AHI was significantly higher in males versus females: 2.7/h versus 2.2/h (p = 0.008). Body mass index [BMI] (β: 0.292, p < 0.001), baseline AHI (β: 0.167, p < 0.001), and age (β: 0.065, p = 0.035) were independent predictors of the therapeutic CPAP level settings.

CONCLUSIONS

Sex does not significantly influence the therapeutic CPAP settings. However, age, BMI, and baseline AHI emerge as independent predictors of the 95^th percentile CPAP requirement during an auto-adjusting CPAP titration.

Assessing the Haemodynamic Impact of Coronary Artery Stenoses: Intracoronary Flow Versus Pressure Measurements

Fractional flow reserve (FFR)-guided percutaneous coronary intervention results in better long-term clinical outcomes compared with coronary angiography alone in intermediate stenoses in stable coronary artery disease (CAD). Coronary physiology measurements have emerged for clinical decision making in interventional cardiology, but the focus lies mainly on epicardial vessels rather than the impact of these stenoses on the myocardial microcirculation. The latter can be quantified by measuring the coronary flow reserve (CFR), a combined pressure and flow index with a strong ability to predict clinical outcomes in CAD. However, combined pressure-flow measurements show 30-40 % discordance despite similar diagnostic accuracy between FFR and CFR, which is explained by the effect of microvascular resistance on both indices. Both epicardial and microcirculatory involvement has been acknowledged in ischaemic heart disease, but clinical implementation remains difficult as it requires individual proficiency. The recent introduced pressure-only index instantaneous wave-free ratio, a resting adenosine-free stenosis assessment, led to a revival of interest in coronary physiology measurements. This review focuses on elaborating the coronary physiological parameters and potential of combined pressure-flow measurements in daily clinical practice.

Comparison of water and air charged transducer catheter pressures in the evaluation of cystometrogram and voiding pressure studies

AIMS

Air-charged (AC) and water-perfused (WP) catheters have been evaluated for differences in measuring pressures for voiding dysfunction. Typically, a two-catheter system was used. We believe that simultaneous pressure measurements with AC and WP in a single catheter will provide analogous pressures for coughs, Valsalvas, and maximum pressures in voiding pressure studies (VPS).

METHODS

This IRB approved prospective study included 50 women over age 21. AC dual TDOC catheters were utilized. The water-filling channel served as the bladder filler and the water pressure readings. Patients were evaluated with empty bladders and at volumes of 50-100 mL, 200 mL, and maximum capacity with cough and Valsalva maneuvers. Comparative analysis was performed on maximum stress peak pressures. At maximum bladder capacity, VPS was done and maximum voiding pressure was recorded.

RESULTS

Comparing coughs and Valsalva maneuvers pressures, there was significant increase in variability between AC and WP measurements with less than 50 mL volume (P < 0.001). Significant correlations were observed between AC and WP measurements for coughs and Valsalvas with bladder volume over 50 mL. Visual impression showed virtually identical tracings. Cough measurements had an average difference of 0.25 cmH₂ O (±8.81) and Valsalva measurements had an average difference of 3.15 cmH₂ O (±4.72). Thirty-eight women had usable maximum voiding pressure measurements and had a strong correlation.

CONCLUSIONS

Cystometrogram and maximum voiding pressure measurements done with either water or air charged catheters will yield similarly accurate results and are comparable. Results suggest more variability at low bladder volumes <50 mL.

Bronchial blockers under pressure: in vitro model and ex vivo model

BACKGROUND

Pressures (Pe) exerted by bronchial blockers on the inner wall of the bronchi may cause mucosal ischaemia. Our aims were as follows: (i) to compare the intracuff pressure (Pi) and Pe exerted by commercially available bronchial blockers in an in vitro and an ex vivo model; (ii) to investigate the influence of both the inflated intracuff volume and cuff diameter on Pe; and (iii) to estimate the minimal sealing volume (VSmin) and the corresponding Pe for each bronchial blocker studied.

METHODS

The Pe exerted by seven commercial bronchial blockers was measured at different inflation volumes using a custom-designed system using in vitro and ex vivo animal models with two internal diameters (12 and 15 mm).

RESULTS

In the same conditions, Pi was significantly lower than Pe (P<0.05), and Pe was higher in the in vitro model than in the ex vivo model. The Pe increased with the inflated volume, with use of the small-diameter model (P<0.05). Ex vivo models needed a higher minimal sealing volume than the in vitro models, and this volume increased with the diameter (e.g. the VSmin at a positive pressure of 25 cm H2O required a Pe ranging from 12 to 78 mm Hg on the 15 mm ex vivo model and from 66 to 110 mm Hg on the 12 mm ex vivo model).

CONCLUSIONS

The Pi cannot be used to approximate Pe. The diameter of the model, the inflated volume, and the bronchial blocker design all influence Pe. A pressure higher than the critical ischaemic threshold (i.e. 25 mm Hg) was needed to prevent air leak around the cuff in the in vitro and ex vivo models.

Validation of pressure gradient and peripheral fractional flow reserve measured by a pressure wire for diagnosis of iliofemoral artery disease with intermediate stenosis

Objective

To examine the pressure gradient and peripheral fractional flow reserve (pFFR) measured by a pressure wire as indicators of hemodynamic significance in iliofemoral angiographic intermediate stenosis.

Background

The utility of pressure measurements using a pressure wire with vasodilators is unclear in cases with intermediate iliofemoral stenosis.

Methods

The mean pressure gradient (MPG) and mean pressure ratio (MPR) were measured at baseline and after injection of isosorbide dinitrate in 23 lesions with angiographically intermediate iliofemoral stenosis. Patients with complex lesions, infrapopliteal artery lesions, chronic total occlusion, and surgical bypass grafts were excluded. Hyperemic MPR was considered equivalent to pFFR. Changes in parameters in response to vasodilators were assessed and correlations of peak systolic velocity ratio (PSVR) with hyperemic MPG and pFFR were examined using duplex ultrasound.

Results

After injection of isosorbide dinitrate, hyperemic MPG increased significantly (from 9.0±5.7 to 16.3±6.2 mmHg; P<0.05) and hyperemic MPR (pFFR) decreased significantly (from 0.92±0.06 to 0.81±0.07; P<0.05). PSVR was significantly correlated with hyperemic MPG (R=0.52; P<0.05) and pFFR (R=−0.50; P<0.05). The optimal cut-off value of pFFR as an indicator of significant hemodynamic stenosis (PSVR >2.5) was 0.85 (area under the curve 0.72; sensitivity 94%; specificity 50%, P<0.05).

Conclusion

pFFR measured using a pressure wire is reliable for prediction of hemodynamic significance in iliofemoral intermediate stenosis.

Correlation between intrasac pressure measurements of a pressure sensor and an angiographic catheter during endovascular repair of abdominal aortic aneurysm

PURPOSE

To establish a correlation between intrasac pressure measurements of a pressure sensor and an angiographic catheter placed in the same aneurysm sac before and after its exclusion by an endoprosthesis.

METHODS

Patients who underwent endovascular abdominal aortic aneurysm repair and received an EndoSure wireless pressure sensor implant between March 19 and December 11, 2004 were enrolled in the study. Simultaneous readings of systolic, diastolic, mean, and pulse pressure within the aneurysm sac were obtained from the catheter and the sensor, both before and after sac exclusion by the endoprosthesis (Readings 1 and 2, respectively). Intrasac pressure measurements were compared using Pearson's correlation and Student's t test. Statistical significance was set at p<0.05.

RESULTS

Twenty-five patients had the pressure sensor implanted, with simultaneous readings (i.e., recorded by both devices) obtained in 19 patients for Reading 1 and in 10 patients for Reading 2. There was a statistically significant correlation for all pressure variables during both readings, with p<0.01 for all except the pulse pressure in Reading 1 (p<0.05). Statistical significance of pressure variations before and after abdominal aortic aneurysm exclusion was coincident between the sensor and catheter for diastolic (p>0.05), mean (p>0.05), and pulse (p<0.01) pressures; the sole disagreement was observed for systolic pressure, which varied, on average, 31.23 mmHg by the catheter (p<0.05) and 22 mmHg (p>0.05) by the sensor.

CONCLUSION

The excellent agreement between intrasac pressure readings recorded by the catheter and the sensor justifies use of the latter for detection of post-exclusion abdominal aortic aneurysm pressurization.