Fluid dynamic factors in tracheal pressure measurement

1981 ◽  
Vol 51 (1) ◽  
pp. 218-225 ◽  
Author(s):  
H. K. Chang ◽  
J. P. Mortola
Keyword(s):  
Endotracheal Tube ◽  
Pressure Measurement ◽  
Fluid Dynamic ◽  
Theoretical Explanation ◽  
Apparent Paradox ◽  
Cross Sectional ◽  
Tracheal Cannula ◽  
Dynamic Factors ◽  
Tracheal Pressure

Because tracheal pressure measurement generally involves the use of a cannula or an endotracheal tube, fluid dynamic factors may cause a considerable artifact. We present a theoretical explanation of the observed apparent paradox in which the resistance of a tracheal cannula or an endotracheal tube is isolation was found to exceed the resistance of the airways plus the cannula or the tube in situ. By estimating the viscous dissipation and the kinetic energy change in a conduit with sudden variation of cross-sectional area, a predictive model is derived. The predictions are verified by a series of in vitro experiments with both steady and oscillatory flows. The experiments showed that the pressure recorded from the sidearm of a tracheal cannula or endotracheal tube contains an error which, in general, increased with the mean Reynolds' number of the through flow and also depends on the diameter ratio between the trachea and the tube or cannula, the position of the pressure tap, and the frequency of ventilation. When feasible, direct measurement with a needle in the trachea is suggested as a way to avoid the possible artifacts arising from the use fo a side tap of the cannula. Theoretical considerations, as well as in vitro and animal experiments, indicate that adding a properly chosen expansion to the tracheal cannula makes it possible to alter inspiratory and expiratory pressures selectively. This device may prove useful in control of breathing studies.

Influence of site of tracheal pressure measurement on in situ estimation of endotracheal tube resistance

1994 ◽  
Vol 77 (6) ◽  
pp. 2899-2906 ◽  
Author(s):  
P. Navalesi ◽  
P. Hernandez ◽  
D. Laporta ◽  
J. S. Landry ◽  
F. Maltais ◽  
...  
Keyword(s):  
Endotracheal Tube ◽  
Fluid Dynamic ◽  
Reference Value ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tracheal Pressure

In situ measurement of distal tracheal pressure (Ptr) via an intraluminal side-hole catheter (IC) has been used to determine endotracheal tube (Rett) and intrinsic patient (Rpt) resistances in intubated subjects. Because of differences in cross-sectional area between the endotracheal tube (ETT) and trachea, fluid dynamic principles predict that IC position should critically influence these results. Accordingly, the aim of this study was to determine the effect of IC position on Rett. Ptr was recorded in vitro through an IC from 2 cm inside, at the tip of, or 2 cm outside an ETT (7, 8, and 9 mm ID) situated within an artificial trachea (13, 18, and 22 mm ID). A reference value of Rett was also obtained. Results were unaffected by IC position during inspiration, overestimating Rett by 7.9 +/- 0.7% (SE). In contrast, during expiration, Rett fell as IC position changed from outside to inside the ETT and was underestimated by 41.3 +/- 3.6% with Ptr recorded inside the ETT. Varying ETT or tracheal size had little effect on the relative error in Rett. The IC itself did increase Rett due to a reduction in effective cross-sectional area, the change varying directly with IC size and inversely with ETT caliber. In vivo values in 11 intubated patients were comparable to in vitro results. In summary, IC position and size can have important consequences on in situ measurements of Ptr and should be considered when clinically monitoring Rett or Rpt.

Experimental Investigation of the Effect of Heart Rate on Flow in the Left Ventricle in Health and Disease—Aortic Valve Regurgitation

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Giuseppe Di Labbio ◽  
Eyal Ben Assa ◽  
Lyes Kadem
Keyword(s):  
Heart Rate ◽  
Left Ventricle ◽  
Fluid Dynamic ◽  
Left Ventricular ◽  
Regurgitant Volume ◽  
Time Resolved ◽  
Dynamic Factors ◽  
Relative Residence Time ◽  
Double Activation

Abstract There is much debate in the literature surrounding the effects of heart rate on aortic regurgitation (AR). Despite the contradictory information, it is still widely believed that an increase in heart rate is beneficial due to the disproportionate shortening of the duration of diastole relative to systole, permitting less time for the left ventricle to fill from regurgitation. This in vitro work investigates how a change in heart rate affects the left ventricular fluid dynamics in the absence and presence of acute AR. The experiments are performed on a novel double-activation left heart simulator previously used for the study of chronic AR. The intraventricular velocity fields are acquired via time-resolved planar particle image velocimetry (PIV) in a clinically relevant plane. Considering fluid dynamic factors, an increase in heart rate was observed to have a limited benefit in the case of mild AR and a detrimental effect for more severe AR. With increasing heart rate, mild AR was associated with a decrease in regurgitant volume, a negligible change in regurgitant volume per diastolic second, and a limited reduction in the fraction of retained regurgitant inflow. More severe AR was accompanied by an increase in both regurgitant volume and the fraction of retained regurgitant inflow, implying a less effective pumping efficiency and a longer relative residence time of blood in the ventricle. Globally, the left ventricle's capacity to compensate for the increase in energy dissipation associated with an increase in heart rate diminishes considerably with severity, a phenomenon which may be exploited further as a method of noninvasive assessment of the severity of AR. These findings may affect the clinical belief that tachycardia is preferred in acute AR and should be investigated further in the clinical setting.

Tracheal pressure and endotracheal tube obstruction can be detected by continuous cuff pressure monitoring: in vitro pilot study

2010 ◽  
Vol 36 (6) ◽  
pp. 984-990 ◽  
Author(s):  
Shai Efrati ◽  
Israel Deutsch ◽  
Gabriel M. Gurman ◽  
Matitiau Noff ◽  
Giorgio Conti
Keyword(s):  
Pilot Study ◽  
Endotracheal Tube ◽  
Cuff Pressure ◽  
Pressure Monitoring ◽  
Tube Obstruction ◽  
Tracheal Pressure

An in vitro Comparison of Two Replacement Techniques Utilizing Fascia Lata after Cranial Cruciate Ligament Transection in the Dog

1993 ◽  
Vol 06 (02) ◽  
pp. 85-92 ◽  
Author(s):  
G. L. Coetzee
Keyword(s):  
Femoral Condyle ◽  
Cruciate Ligament ◽  
Maximum Load ◽  
Fascia Lata ◽  
Patellar Ligament ◽  
Cross Sectional ◽  
Cranial Cruciate Ligament ◽  
Replacement Technique ◽  
Over The Top

SummaryThe immediate postoperative biomechanical properties of an “underand-over” cranial cruciate ligament (CCL) replacement technique consisting of fascia lata and the lateral onethird of the patellar ligament, were compared with that of a modified intra- and extracapsular “under-and-over-the-top” (UOTT) method. The right CCL in twelve adult dogs was dissected out and replaced with an autograft. The contralateral, intact CCL served as the control. In group A, the graft was secured to the lateral femoral condyle with a spiked washer and screw. In group B the intracapsular graft was secured to the lateral femoro-fabellar ligament, and the remainder to the patellar tendon. Both CCL replacement techniques exhibited a 2.0 ± 0.5 mm anterior drawer immediately after the operation. After skeletonization of the stifles, the length and cross-sectional area of the intact CCL and CCL substitutes were determined. Each bone-ligament unit was tested in linear tension to failure at a fixed distraction rate of 15 mm/s with the stifle in 120° flexion. Data was processed to obtain the corresponding material parameters (modulus, stress and strain in the linear loading region, and energy absorption to maximum load).The immediate postoperative structural and material properties of the “under-and-over” cranial cruciate ligament replacement technique with autogenous fascia lata, were compared to that of a modified intra- and extracapsular “under-and-over-the-top” (UOTT) method. The combined UOT T technique was slightly stronger (6%), but allowed 2.8 ± 0.9 mm more cranial tibial displacement at maximum linear force.

scholarly journals Occupational Exposure to Carbon Nanotubes and Carbon Nanofibres: More Than a Cobweb

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 745
Author(s):  
Enrico Bergamaschi ◽  
Giacomo Garzaro ◽  
Georgia Wilson Jones ◽  
Martina Buglisi ◽  
Michele Caniglia ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Animal Studies ◽  
Chemical Properties ◽  
Biological Behavior ◽  
Cross Sectional ◽  
Carbon Nanofibres ◽  
Material Entity ◽  
Cross Sectional Design

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are erroneously considered as singular material entities. Instead, they should be regarded as a heterogeneous class of materials bearing different properties eliciting peculiar biological outcomes both in vitro and in vivo. Given the pace at which the industrial production of CNTs/CNFs is increasing, it is becoming of utmost importance to acquire comprehensive knowledge regarding their biological activity and their hazardous effects in humans. Animal studies carried out by inhalation showed that some CNTs/CNFs species can cause deleterious effects such as inflammation and lung tissue remodeling. Their physico-chemical properties, biological behavior and biopersistence make them similar to asbestos fibers. Human studies suggest some mild effects in workers handling CNT/CNF. However, owing to their cross-sectional design, researchers have been as yet unable to firmly demonstrate a causal relationship between such an exposure and the observed effects. Estimation of acceptable exposure levels should warrant a proper risk management. The aim of this review is to challenge the conception of CNTs/CNFs as a single, unified material entity and prompt the establishment of standardized hazard and exposure assessment methodologies able to properly feeding risk assessment and management frameworks.

scholarly journals Large intraperitoneal lipoleiomyoma in a pre-menopausal woman: a case report

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Sara L. Schaefer ◽  
Amy L. Strong ◽  
Sheena Bahroloomi ◽  
Jichang Han ◽  
Michella K. Whisman ◽  
...  
Keyword(s):  
Differential Diagnosis ◽  
Smooth Muscle ◽  
Case Report ◽  
Smooth Muscle Actin ◽  
Abdominal Mass ◽  
Histopathological Analysis ◽  
Menopausal Woman ◽  
En Bloc ◽  
Cross Sectional

Abstract Background Lipoleiomyoma is a rare, benign variant of the commonplace uterine leiomyoma. Unlike leiomyoma, these tumors are composed of smooth muscle cells admixed with mature adipose tissue. While rare, they are most frequently identified in the uterus, but even more infrequently have been described in extrauterine locations. Case presentation We describe a case report of a 45-year-old woman with a history of in vitro fertilization pregnancy presenting 6 years later with abdominal distention and weight loss found to have a 30-cm intra-abdominal lipoleiomyoma. While cross-sectional imaging can narrow the differential diagnosis, histopathological analysis with stains positive for smooth muscle actin, desmin, and estrogen receptor, but negative for HMB-45 confirms the diagnosis of lipoleiomyoma. The large encapsulated tumor was resected en bloc. The patients post-operative course was uneventful and her symptoms resolved. Conclusions Lipoleiomyoma should be considered on the differential diagnosis in a woman with a large intra-abdominal mass. While considered benign, resection should be considered if the mass is symptomatic, and the diagnosis is unclear or there is a concern for malignancy.

Determinants of serum adiponectin levels: a cross-sectional study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Azar Sattarinezhad ◽  
Akbar Rasekhi Kazerouni ◽  
Gholamhossein Ranjbar Omrani ◽  
Mesbah Shams
Keyword(s):  
Ovarian Cancer ◽  
Germ Line ◽  
Brca Mutation ◽  
Bilateral Mastectomy ◽  
Ovarian Cancer Risk ◽  
Breast And Ovarian Cancer ◽  
Double Blind ◽  
Cross Sectional ◽  
Mutation Carriers

Abstract Objectives To review non-surgical prevention strategies in women with hereditary breast and ovarian cancer syndromes. Content Women with a gBRCA1 or 2 mutations face a high cumulative breast and ovarian cancer risk. While bilateral mastectomy (PBM) and bilateral salpingo-oophrectomy (PBSO) profoundly reduce the respective cancer risks, they are also associated with considerable side effects. There is therefore an urgent need for alternative and non-surgical risk reduction options. Tamoxifen and aromatase inhibitors have both been evaluated in secondary prevention, but their benefit in primary prevention is currently unknown in BRCA mutation carriers. In addition, their use is compromised by their side effect profile which makes them less appealing for a use in chemoprevention. Summary and outlook Denosumab is a well-tolerated osteoprotective drug, which has been demonstrated to have a potential preventive effect particularly in BRCA1-deficient models in vitro. The prospectively randomized double-blind BRCA-P trial is currently investigating the preventative effect of denosumab in healthy BRCA1 germ line mutation carriers.

Prehospital Intubations Are Associated with Elevated Endotracheal Tube Cuff Pressures: A Cross-Sectional Study Characterizing ETT Cuff Pressures at a Tertiary Care Emergency Department

2021 ◽  
pp. 1-4
Author(s):  
Ruo S. Chen ◽  
Laurel O’Connor ◽  
Matthew R. Rebesco ◽  
Kara L. LaBarge ◽  
Edgar J. Remotti ◽  
...  
Keyword(s):  
Endotracheal Tube ◽  
Cuff Pressure ◽  
Care Center ◽  
Tertiary Care ◽  
Cross Sectional Study ◽  
Endotracheal Tube Cuff ◽  
Cross Sectional ◽  
Tube Cuff ◽  
Respiratory Therapists ◽  
Significant Difference

Abstract Introduction: Emergency Medical Services (EMS) providers are trained to place endotracheal tubes (ETTs) in the prehospital setting when indicated. Endotracheal tube cuffs are traditionally inflated with 10cc of air to provide adequate seal against the tracheal lumen. There is literature suggesting that many ETTs are inflated well beyond the accepted safe pressures of 20-30cmH2O, leading to potential complications including ischemia, necrosis, scarring, and stenosis of the tracheal wall. Currently, EMS providers do not routinely check ETT cuff pressures. It was hypothesized that the average ETT cuff pressure of patients arriving at the study site who were intubated by EMS exceeds the safe pressure range of 20-30cmH2O. Objectives: While ETT cuff inflation is necessary to close the respiratory system, thus preventing air leaks and aspiration, there is evidence to suggest that over-inflated ETT cuffs can cause long-term complications. The purpose of this study is to characterize the cuff pressures of ETTs placed by EMS providers. Methods: This project was a single center, prospective observational study. Endotracheal tube cuff pressures were measured and recorded for adult patients intubated by EMS providers prior to arrival at a large, urban, tertiary care center over a nine-month period. All data were collected by respiratory therapists utilizing a cuff pressure measurement device which had a detectable range of 0-100cmH2O and was designed as a syringe. Results including basic patient demographics, cuff pressure, tube size, and EMS service were recorded. Results: In total, 45 measurements from six EMS services were included with ETT sizes ranging from 6.5-8.0mm. Mean patient age was 52.2 years (67.7% male). Mean cuff pressure was 81.8cmH2O with a range of 15 to 100 and a median of 100. The mode was 100cmH2O; 40 out of 45 (88.9%) cuff pressures were above 30cmH2O. Linear regression showed no correlation between age and ETT cuff pressure or between ETT size and cuff pressure. Two-tailed T tests did not show a significant difference in the mean cuff pressure between female versus male patients. Conclusion: An overwhelming majority of prehospital intubations are associated with elevated cuff pressures, and cuff pressure monitoring education is indicated to address this phenomenon.

scholarly journals The Effect of Stress, Anxiety and Depression on In Vitro Fertilization Outcome in Kazakhstani Public Clinical Setting: A Cross-Sectional Study

2021 ◽  
Vol 10 (5) ◽  
pp. 937
Author(s):  
Gauri Bapayeva ◽  
Gulzhanat Aimagambetova ◽  
Alpamys Issanov ◽  
Sanja Terzic ◽  
Talshyn Ukybassova ◽  
...  
Keyword(s):  
In Vitro Fertilization ◽  
Depressed Mood ◽  
Depression Scale ◽  
Anxiety Scale ◽  
Clinical Depression ◽  
Cross Sectional ◽  
Vitro Fertilization ◽  
Scale Scores ◽  
The Impact

Although it is clear that infertility leads to heightened stress for patients, the impact of depressed mood and anxiety on treatment outcome is inconsistently reported. The aim of this study was to evaluate the effect of stress, depression and anxiety on in vitro fertilization (IVF) outcomes in Kazakhstani public assisted reproductive technology (ART) clinics. The prospective cohort study was performed between June 2019 and September 2020 using questionnaires to assess psychological stress, depressed mood and anxiety in women referred to IVF clinics in two public clinical centers in Kazakhstan, Nur-Sultan and Aktobe. Our study sample comprised 142 women with the average age of 33.9 ± 4.9 years, and infertility duration 6.0 ± 3.5 years. More than half of respondents had Center for Epidemiological Studies Depression Scale (CES-D) scores higher than 16, indicating their risk of developing clinical depression. Ninety-one percent of women from Aktobe city were at risk for clinical depression (p < 0.001). Aktobe city respondents had higher stress subscale scores and anxiety scale scores (p < 0.001) than Nur-Sultan respondents. Statistical analysis showed that IVF outcome was not significantly associated with depression and stress, while the higher anxiety scale scores were negatively associated with clinical pregnancy after IVF.

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