Extra-alveolar vessel fluid filtration coefficients in excised and in situ canine lobes

1985 ◽  
Vol 59 (5) ◽  
pp. 1555-1559 ◽  
Author(s):  
R. K. Albert ◽  
W. Kirk ◽  
C. Pitts ◽  
J. Butler
Keyword(s):  
Lung Volume ◽  
Pulmonary Circulation ◽  
Alveolar Pressure ◽  
Fluid Filtration ◽  
Significant Difference ◽  
The Mean ◽  
Stop Flow ◽  
Total Circulation ◽  
Total Fluid

We continuously weighed fully distended excised or in situ canine lobes to estimate the fluid filtration coefficient (Kf) of the arterial and venous extra-alveolar vessels compared with that of the entire pulmonary circulation. Alveolar pressure was held constant at 25 cmH2O after full inflation. In the in situ lobes, the bronchial circulation was interrupted by embolization. Kf was estimated by two methods (Drake and Goldberg). Extra-alveolar vessels were isolated from alveolar vessels by embolizing enough 37- to 74-micron polystyrene beads into the lobar artery or vein to completely stop flow. In excised lobes, Kf's of the entire pulmonary circulation by the Drake and Goldberg methods were 0.122 +/- 0.041 (mean +/- SD) and 0.210 +/- 0.080 ml X min-1 X mmHg-1 X 100 g lung-1, respectively. Embolization was not found to increase the Kf's. The mean Kf's of the arterial extra-alveolar vessels were 0.068 +/- 0.014 (Drake) and 0.069 +/- 0.014 (Goldberg) (24 and 33% of the Kf's for the total pulmonary circulation). The mean Kf's of the venous extra-alveolar vessels were similar [0.046 +/- 0.020 (Drake) and 0.065 +/- 0.036 (Goldberg) or 33 and 35% of the Kf's for the total circulation]. No significant difference was found between the extra-alveolar vessel Kf's of in situ vs. excised lobes. These results suggest that when alveolar pressure, lung volume, and pulmonary vascular pressures are high, approximately one-third of the total fluid filtration comes from each of the three compartments.

Alveolar pressure and lung volume as determinants of net transvascular fluid filtration

1977 ◽  
Vol 42 (4) ◽  
pp. 476-482 ◽  
Author(s):  
G. Bo ◽  
A. Hauge ◽  
G. Nicolaysen
Keyword(s):  
Lung Volume ◽  
Continuous Monitoring ◽  
Interstitial Fluid ◽  
Positive Airway Pressure ◽  
Fluid Pressure ◽  
Alveolar Pressure ◽  
Experimental Conditions ◽  
Fluid Filtration ◽  
Pulmonary Arterial ◽  
Relative Change

We have investigated the influence of changes in alveolar pressure (PAlv) and in lung volume on the net transvascular fluid filtration rate (FFR). The preparation was isolated, perfused zone III rabbit lungs. In observation periods the outflow pressure was kept constant at a level generally causing net filtration. All pressures were measured relative to atmospheric. FFR was measured by continuous monitoring of preparation weight. Elevation of Palv at constant lung volume caused reversible reductions in FFR, also at constant capillary hydrostatic pressure (Pa-V less than 2 Torr). Increases in lung volume at constant PAlv caused reversible increases in FFR. When both PAlv and Ptp were increased a reduction in FFR was seen in the majority of cases. We conclude that at constant pulmonary arterial pressure, the size and the direction of the influence of positive airway pressure on FFR depend on the relative change in lung volume and in alveolar pressure per se. Under the present experimental conditions a rise in PAlv will be transmitted to interstitial fluid pressure and affect the transvascular fluid balance.

Peribronchial pressure in excised dog lungs

1978 ◽  
Vol 45 (6) ◽  
pp. 858-869 ◽  
Author(s):  
H. Sasaki ◽  
F. G. Hoppin ◽  
T. Takishima
Keyword(s):  
Smooth Muscle ◽  
Lung Volume ◽  
Radial Stress ◽  
Similar Magnitude ◽  
Alveolar Pressure ◽  
Lung Inflation ◽  
Bronchial Wall ◽  
Lobar Bronchus ◽  
Intrabronchial Pressure

To characterize the stresses which determine bronchial diameter in the lung, we estimated peribronchial pressure (Px) relative to intrabronchial pressure (Pbr) and to alveolar pressure (PA) for the main lobar bronchus of excised dog lobes using the technique of Takishima et al. (J. Appl. Physiol. 38: 875--881, 1975). The recoil of the bronchial wall, Pbr---Px, when smooth muscle was relaxed varied primarily with bronchial diameter. The recoil of the parenchyma around the bronchus, Px---Pa, varied with lung volume but was also diameter-dependent and served to double approximately the effective elastance of the bronchus in situ. We estimated recoils during slow deflations from TLC with the bronchus untreated, or pharmacologically contracted or relaxed. In untreated and relaxed states, local parenchymal and bronchial recoils were of similar magnitude to overall lung recoil (i.e., Px congruent to Ppl) except at high inflating pressure (PA -- Ppl = 30 cmH2O) where they were about half as great. With contraction, bronchial and local parenchymal recoils increased to as much as twice overall lung recoil. Contracted smooth muscle exerted a radial stress of 36+/-14 cmH2O at full lung inflation but much less during stepwise deflation.

Effect of surface tension on circulation in the excised lungs of dogs

1964 ◽  
Vol 19 (4) ◽  
pp. 707-712 ◽  
Author(s):  
I. Bruderman ◽  
K. Somers ◽  
W. K. Hamilton ◽  
W. H. Tooley ◽  
J. Butler
Keyword(s):  
Surface Tension ◽  
Arterial Pressure ◽  
Pulmonary Vascular Resistance ◽  
Lung Volume ◽  
Pulmonary Circulation ◽  
Pulmonary Arterial Pressure ◽  
Alveolar Pressure ◽  
Pulmonary Arterial ◽  
Air Liquid Interface ◽  
Effect Of Surface

The hypothesis that the surface tension of the fluid film which lines the lung alveoli reduces the pericapillary pressure in air-filled lungs was tested by perfusing the excised lungs of dogs with saline, 6% dextran in saline, and blood. After almost maximal inflation with air from low volumes or the degassed state (inflation state) the pulmonary arterial pressure, relative to the base of the lungs, was lower than the alveolar pressure with flows up to 50 ml/min. It was higher than the alveolar pressure at any flow when the air-liquid interface had been abolished by filling the lungs to the same volume with fluid. The pulmonary arterial pressure at the same flow and alveolar pressure was lower in the inflation state than after deflation from higher volumes (the deflation state). However, lung volume was larger in the deflation state. The possibility of some low resistance channels in the inflation state could not be excluded. However, histological examinations showed that the alveolar capillaries were patent and failed to show any airless lung. pulmonary circulation; pericapillary pressure in lungs; surface tension and pulmonary vascular resistance Submitted on July 29, 1963

Determinants of transvascular fluid shifts in zone I lungs

1980 ◽  
Vol 48 (2) ◽  
pp. 256-264 ◽  
Author(s):  
G. Nicolaysen ◽  
A. Hauge
Keyword(s):  
Lung Volume ◽  
Transmural Pressure ◽  
Pleural Pressure ◽  
Alveolar Pressure ◽  
Fluid Filtration ◽  
Fluid Shifts ◽  
Transvascular Fluid Shifts

We studied the fluid shifts in isolated, plasma-perfused rabbit lungs kept completely within zone I. The rate of fluid filtration or reabsorption was determined gravimetrically. A rise in alveolar pressure at constant pleural and vascular pressures reduced th rate of filtration or increased the rate of reabsorption in seven of eight lungs. In seven of seven lungs a reduction in pleural pressure at constant alveolar and vascular pressures increased the rate of filtration or decreased the rate of reabsorption. Thus, a given rise in lung volume had opposite effects depending on whether this rise was caused by an increased alveolar or reduced pleural pressure. Therefore, the exchange vessels studied cannot be true extra-alveolar vessels, which always expand (reflecting a rise in transmural pressure) with a rise in lung volume. When alveolar and pleural pressures were equally increased at constant vascular pressure, the rate of filtration was reduced in four of four lungs. The results can be explained through the existence of exchange vessels situated neither in the alveolar septae proper nor among the true extra-alveolar vessels. The vessels in the alveolar junctions are the most likely candidates.

scholarly journals Influence of toothbrushing on enamel softening and abrasive wear of eroded bovine enamel: an in situ study

2006 ◽  
Vol 20 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Daniela Rios ◽  
Heitor Marques Honório ◽  
Ana Carolina Magalhães ◽  
Marília Afonso Rabelo Buzalaf ◽  
Regina Guenka Palma-Dibb ◽  
...  
Keyword(s):  
Abrasive Wear ◽  
The Other ◽  
In Situ Study ◽  
Significant Difference ◽  
The Mean ◽  
Student’S T ◽  
Bovine Enamel ◽  
Enamel Layer ◽  
Student’S T Test

This study assessed the surface softening and abrasive wear of eroded bovine enamel with or without the influence of toothbrushing. Five volunteers took part in this in situ study of 5 days. They wore acrylic palatal appliances containing 6 bovine enamel blocks divided in two rows with 3 blocks, which corresponded to the studied groups: erosion without toothbrushing (GI) and erosion with toothbrushing (GII). The blocks were subjected to erosion by immersion of the appliances in a cola drink for 10 minutes, 4 times a day. After that, no treatment was performed in one row (GI), whereas the other row was brushed (GII). The appliance was then replaced into the mouth. Enamel alterations were determined using profilometry and microhardness tests. Data were tested using paired Student’s t test (p < 0.05). The mean wear values (µm) and percentage of superficial microhardness change (%SMHC) were respectively: GI - 2.77 ± 1.21/91.61 ± 3.68 and GII - 3.80 ± 0.91/58.77 ± 11.47. There was a significant difference in wear (p = 0.001) and %SMHC (p = 0.001) between the groups. It was concluded that the wear was more pronounced when associated to toothbrushing abrasion. However, toothbrushing promoted less %SMHC due to the removal of the altered superficial enamel layer.

scholarly journals Melanomas and Dysplastic Nevi Differ in Epidermal CD1c+ Dendritic Cell Count

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Grzegorz Dyduch ◽  
Katarzyna Ewa Tyrak ◽  
Anna Glajcar ◽  
Joanna Szpor ◽  
Magdalena Ulatowska-Białas ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Dendritic Cell ◽  
Cell Count ◽  
Immune Surveillance ◽  
Melanocytic Nevi ◽  
Dysplastic Nevi ◽  
Melanoma In Situ ◽  
Significant Difference ◽  
The Mean

Background. Dendritic cells could be involved in immune surveillance of highly immunogenic tumors such as melanoma. Their role in the progression melanocytic nevi to melanoma is however a matter of controversy. Methods. The number of dendritic cells within epidermis, in peritumoral zone, and within the lesion was counted on slides immunohistochemically stained for CD1a, CD1c, DC-LAMP, and DC-SIGN in 21 of dysplastic nevi, 27 in situ melanomas, and 21 invasive melanomas. Results. We found a significant difference in the density of intraepidermal CD1c+ cells between the examined lesions; the mean CD1c cell count was 7.00/mm2 for invasive melanomas, 2.94 for in situ melanomas, and 13.35 for dysplastic nevi. The differences between dysplastic nevi and melanoma in situ as well as between dysplastic nevi and invasive melanoma were significant. There was no correlation in number of positively stained cells between epidermis and dermis. We did not observe any intraepidermal DC-LAMP+ cells neither in melanoma in situ nor in invasive melanoma as well as any intraepidermal DC-SIGN+ cells in dysplastic nevi. Conclusion. It was shown that the number of dendritic cells differs between dysplastic nevi, in situ melanomas, and invasive melanomas. This could eventually suggest their participation in the development of melanoma.

scholarly journals Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

2021 ◽  
Vol 10 (3) ◽  
pp. 129-137
Author(s):  
Mariam A Elshawarby ◽  
Ali Saad ◽  
Thanaa Helmy ◽  
Mouamen M. Seleet ◽  
Tamer Elraggal
Keyword(s):  
Visual Acuity ◽  
Refractive Error ◽  
Ablation Depth ◽  
Laser In Situ Keratomileusis ◽  
Treatment Modalities ◽  
Significant Difference ◽  
Corneal Asphericity ◽  
Optical Zone ◽  
The Mean

Background: Many studies have used functional optical zone (FOZ) as a measure to compare different refractive laser treatment modalities. However, to our knowledge, no study has compared wavefrontoptimized (WFO) and wavefront-guided (WFG) laser in situ keratomileusis (LASIK) using FOZ. We compared the FOZ after WFO versus WFG LASIK in patients with myopia and myopic astigmatism.Methods: In this prospective comparative study, we included 100 myopic eyes of 50 patients with or without astigmatism. They were divided into two groups according to the platform used: WFO or WFG femtosecond LASIK. Using Holladay’s equivalent keratometry reading (EKR) report of Pentacam HR, FOZ was defined as a zone centered on the pupil center with a standard deviation (SD) of 0.5 D, around the mean EKR. The differences in FOZ between the two platforms were analyzed at 3 months postoperatively. Visual acuity, refractive error, corneal asphericity (Q-value), and root mean square of higher-order aberrations (RMS for HOAs) were evaluated and compared.Results: The mean ± SD of patient age was 26.64 ± 5.67 years. The preoperative characteristics of the two groups were comparable (all P > 0.05). The intended optical zone (IOZ) was 6 mm in both groups. The mean laser ablation depth was significantly greater in the WFG group (18 ?m per D) than in the WFO group (16 ?m per D) (P = 0.035). At 3 months postoperatively, the mean ± SD of FOZ diameter was 4.32 ± 0.94 mm (71.99 ± 15.68% of intended optical zone) in the WFO group and 4.16 ± 1.13 mm (69.33 ± 18.78% of intended optical zone) in the WFG group, with no significant difference between the two groups (P = 0.622). The change in corneal asphericity was greater in the WFG group than in the WFO group (P = 0.034). Postoperative mean corrected and uncorrected distance visual acuity, manifest refraction, and RMS for HOAs showed no significant difference between the two groups (all P > 0.05).Conclusions: We found that WFG LASIK resulted in greater ablation depth and change in corneal asphericity than WFO LASIK at 3 months postoperatively. However, there was no significant difference in FOZ diameter, refractive error, and RMS for HOAs between the two groups. Further research is needed to confirm these findings.

Effect of alveolar hypoxia on pulmonary fluid filtration in in situ dog lungs

1988 ◽  
Vol 65 (1) ◽  
pp. 46-52 ◽  
Author(s):  
L. A. Homik ◽  
Z. Bshouty ◽  
R. B. Light ◽  
M. Younes
Keyword(s):  
Repeated Measures ◽  
Edema Formation ◽  
Fluid Filtration ◽  
Wide Range ◽  
Significant Difference ◽  
Co2 Balance ◽  
Alveolar Hypoxia ◽  
Group 2 ◽  
Pulmonary Microcirculation

We have studied the effect of alveolar hypoxia on fluid filtration characteristics of the pulmonary microcirculation in an in situ left upper lobe preparation with near static flow conditions (20 ml/min). In six dogs (group 1), rate of edema formation (delta W/delta t, where W is weight and t is time) was assessed over a wide range of vascular pressures under two inspired O2 fraction (FIO2) conditions (0.95 and 0.0 with 5% CO2-balance N2 in both cases). delta W/delta t was plotted against vascular pressure, and the best-fit linear regression was obtained. There was no significant difference (paired t test) in either threshold pressure for edema formation [18.3 +/- 1.8 and 17.1 +/- 1.2 (SE) mmHg, respectively] or the slopes (0.067 +/- 0.008 and 0.073 +/- 0.017 g.min-1. mmHg-1.100g-1, respectively). In another seven dogs (group 2), delta W/delta t was obtained at a constant vascular pressure of 40 mmHg under four FIO2 conditions (0.95, 0.21, 0.05, and 0.0, with 5% CO2-balance N2). Delta W/delta t for the four conditions averaged 0.60 +/- 0.11, 0.61 +/- 0.11, 0.61 +/- 0.10, and 0.61 +/- 0.10 (SE) g.min-1.mmHg-1.100g-1, respectively. No significant differences (ANOVA for repeated measures) were noted. We conclude that alveolar hypoxia does not alter the threshold for edema formation or delta W/delta t at a given microvascular pressure.

The evolution of breast cancer screening in the Medicare population: Clinical and economic implications.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 1595-1595
Author(s):  
Brigid K. Killelea ◽  
Jessica B. Long ◽  
Xiaomei Ma ◽  
Rong Wang ◽  
Anees B. Chagpar ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Digital Mammography ◽  
Early Stage ◽  
Early Period ◽  
Stage At Diagnosis ◽  
Economic Implications ◽  
Medicare Program ◽  
Significant Difference ◽  
The Mean

1595 Background: Breast screening has evolved as newer approaches to mammography, ultrasound, and MRI have diffused into clinical practice. The use of these technologies and their impact on screening-related costs and outcomes remain undefined, particularly among older women. Methods: Using the Surveillance Epidemiology and End Results – Medicare linked database, we identified women aged 66 and older without a diagnosis of breast cancer. We constructed two cohorts (2001 vs. 2006) and followed each for two years. We assessed changes in imaging technology, screening-related costs (defined as costs for screening and subsequent imaging and testing, adjusted to 2009 USD), and stage at diagnosis between the two cohorts. Results: There were 136,845 women in the 2001-2002 (earlier) cohort and 137,733 in the 2006-2007 (later) cohort. The mean age was 76.9 and 77.2 respectively, (p<.001). The proportion of women receiving any screening mammogram was 42.5% in the earlier cohort and 43.4% in the later cohort, (p<.001). The use of digital mammography for screening increased from 2.2% to 15.0%, (p<.001). The use of any computer aided detection (CAD) increased from 3.2% to 29.3% (p<.001). MRI use increased from 0.03% to 0.2%, and ultrasound use from 4.0% to 4.5% (p <.001 for both). Average screening-related cost increased 31%, from $101 to $132 (p<.001). There was no significant difference in early stage at diagnosis over time (58.1% of women were in situ/stage I in early period vs. 57.2% in later period, p=.65). Conclusions: The use of digital mammography and CAD increased substantially between 2001 and 2007, contributing to a 31% increase in screening-related costs for women in the Medicare program. The increased cost of screening and downstream testing must be evaluated in context of an absence of benefit in terms of stage at diagnosis.

scholarly journals Healing Status of Meniscal Ramp Lesion Affects Anterior Knee Stability After ACL Reconstruction

2020 ◽  
Vol 8 (5) ◽  
pp. 232596712091767 ◽  
Author(s):  
Kazuhisa Hatayama ◽  
Masanori Terauchi ◽  
Kenichi Saito ◽  
Ryota Takase ◽  
Hiroshi Higuchi
Keyword(s):  
Acl Reconstruction ◽  
Pivot Shift ◽  
Pivot Shift Test ◽  
Knee Stability ◽  
Ramp Lesion ◽  
Significant Difference ◽  
Mri Scans ◽  
The Mean ◽  
Postoperative Knee

Background: Although the biomechanical importance of the ramp lesion in the anterior cruciate ligament (ACL)–deficient knee has been demonstrated, there is no clear consensus on the appropriate treatment for ramp lesions during ACL reconstruction. Purpose: To compare the postoperative outcomes for ramp lesions between patients treated with all-inside repair through the posteromedial portal and those whose ramp lesions were left in situ without repair during ACL reconstruction. We also determined whether ramp lesion healing status affected postoperative knee stability. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 57 patients who underwent anatomic double-bundle ACL reconstruction between August 2011 and December 2017 had attendant ramp lesions. Of these, 25 ramp lesions that were considered stable were left in situ without repair (Nonrepaired group), and 25 ramp lesions, including 21 stable and 4 unstable lesions, were treated using all-inside repair through the posteromedial portal (Repaired group). We evaluated the side-to-side difference (SSD) in anterior tibial translation on stress radiographs and rotational stability by using the pivot-shift test 2 years after surgery, and healing status of the ramp lesions was evaluated on 3.0-T magnetic resonance imaging (MRI) scans 1 year after surgery. Results: The mean SSDs in anterior translation were 2.4 ± 1.6 mm for the Nonrepaired group and 1.9 ± 1.6 mm for the Repaired group, with no significant differences. The positive ratios on the pivot-shift test were not significantly different between groups. Healing rates of ramp lesions on MRI scans showed a significant difference between the Nonrepaired group (60%) and the Repaired group (100%) ( P = .001). The mean SSDs for knees in which the ramp lesion had healed as shown on MRI scans and those in which it had not healed were 1.9 ± 1.6 mm and 3.2 ± 1.1 mm, respectively, which was a significant difference ( P = .02). Conclusion: Healing rates of ramp lesions were significantly better in the Repaired group than in the Nonrepaired group, although postoperative knee stability was not significantly different between groups. Anterior laxity in the knees in which the ramp lesion was unhealed was significantly greater compared with the knees in which the ramp lesion healed. All-inside repair through the posteromedial portal was a reliable surgical procedure to heal ramp lesions.

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