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1.
Wada, Kazuko, Alan H. Jobe, and Machiko Ikegami. Tidalvolume effects on surfactant treatment responses with the initiation ofventilation in preterm lambs. J. Appl.Physiol. 83(4): 1054-1061, 1997.We hypothesizedthat initiation of ventilation in preterm lambs with high volumes wouldcause lung injury and decrease the subsequent response to surfactanttreatment. Preterm lambs were randomized to ventilation for 30 minafter birth with 5 ml/kg (VT5),10 ml/kg (VT10), or 20 ml/kg(VT20) tidal volumes and then ventilated with ~10 ml/kg tidal volumes to achieve arterialPCO2 values of ~50 Torr to 6 h ofage. VT20 lambs had lowercompliances, lower ventilatory efficiencies, higher recoveries ofprotein, and lower recoveries of surfactant in alveolar lavages and in surfactant that had decreased compliances when tested in preterm rabbits than VT5 orVT10 lambs. Other lambsrandomized to treatment with surfactant at birth and ventilation with6, 12, or 20 ml/kg tidal volumes for 30 min had no indicators of lunginjury. An initial tidal volume of 20 ml/kg decreased the subsequentresponse to surfactant treatment, an effect that was prevented withsurfactant treatment at birth. 相似文献
2.
Kurth F Zinnow F Prakapenia A Dietl S Winkler S Ifflaender S Rüdiger M Burkhardt W 《PloS one》2011,6(6):e21003
Background
Electrical Impedance measurements can be used to estimate the content of intra-thoracic air and thereby give information on pulmonary ventilation. Conventional Impedance measurements mainly indicate relative changes, but no information concerning air-volume is given. The study was performed to test whether a 3-point-calibration with known tidal volumes (VT) during conventional mechanical ventilation (CMV) allows subsequent calculation of VT from total Tidal-Impedance (tTI) measurements using Quadrant Impedance Measurement (QIM). In addition the distribution of TI in different regions of the thorax was examined.Methodology and Principal Findings
QIM was performed in five neonatal piglets during volume-controlled CMV. tTI values at three different VT (4, 6, 8 ml/kg) were used to establish individual calibration curves. Subsequently, each animal was ventilated with different patterns of varying VT (2–10 ml/kg) at different PEEP levels (0, 3, 6, 9, 12 cmH2O). VT variation was repeated after surfactant depletion by bronchoalveolar lavage. VT was calculated from tTI values (VTcalc) and compared to the VT delivered by the ventilator (VTPNT). Bland-Altman analysis revealed good agreement between VTcalc and VTPNT before (bias −0.08 ml; limits of agreement −1.18 to 1.02 ml at PEEP = 3 cmH2O) and after surfactant depletion (bias −0.17 ml; limits of agreement −1.57 to 1.22 ml at PEEP = 3 cmH2O). At higher PEEP levels VTcalc was lower than VTPNT, when only one fixed calibration curve (at PEEP 3 cmH2O) was used. With a new calibration curve at each PEEP level the method showed similar accuracy at each PEEP level. TI showed a homogeneous distribution over the four assessed quadrants with a shift toward caudal regions of the thorax with increasing VT.Conclusion
Tidal Impedance values could be used for precise and accurate calculation of VT during CMV in this animal study, when calibrated at each PEEP level. 相似文献3.
Gadolinium prevents high airway pressure-induced permeability increases in isolated rat lungs 总被引:10,自引:0,他引:10
Parker James C.; Ivey Claire L.; Tucker J. Allan 《Journal of applied physiology》1998,84(4):1113-1118
To determine theinitial signaling event in the vascular permeability increase afterhigh airway pressure injury, we compared groups of lungs ventilated atdifferent peak inflation pressures (PIPs) with (gadolinium group) andwithout (control group) infusion of 20 µM gadolinium chloride, aninhibitor of endothelial stretch-activated cationchannels. Microvascular permeability was assessed by using the capillary filtration coefficient(Kfc), ameasure of capillary hydraulic conductivity.Kfc was measuredafter ventilation for 30-min periods with 7, 20, and 30 cmH2O PIP with 3 cmH2O positive end-expiratorypressure and with 35 cmH2O PIPwith 8 cmH2O positive end-expiratory pressure. In control lungs,Kfc increasedsignificantly to 1.8 and 3.7 times baseline after 30 and 35 cmH2O PIP, respectively. In thegadolinium group,Kfc was unchangedfrom baseline (0.060 ± 0.010 ml · min1 · cmH2O1 · 100 g1) after any PIPventilation period. Pulmonary vascular resistance increasedsignificantly from baseline in both groups before the lastKfc measurementbut was not different between groups. These results suggest thatmicrovascular permeability is actively modulated by a cellular responseto mechanical injury and that stretch-activated cation channels mayinitiate this response through increases in intracellular calciumconcentration. 相似文献
4.
Effects of a synthetic lung surfactant on pharyngeal patency in awake human subjects 总被引:3,自引:0,他引:3
Van der Touw, T., A. B. H. Crawford, and J. R. Wheatley.Effects of a synthetic lung surfactant on pharyngeal patency inawake human subjects. J. Appl.Physiol. 82(1): 78-85, 1997.We examined theeffects of separate applications of saline and a synthetic lungsurfactant preparation (Surf; Exosurf Neonatal) into the supraglotticairway (SA) on the anteroposterior pharyngeal diameter(Dap) and theairway pressures required to close (Pcl) and reopen (Pop) theSA in five awake normal supine subjects. Dap, Pcl, and Popwere determined during lateral X-ray fluoroscopy and voluntary glotticclosure when pressure applied to the SA lumen was decreasedfrom 0 to 20 cmH2O and thenincreased to +20 cmH2O. After Surfapplication and relative to control,Dap was largerfor most of the applied pressures, Pcl decreased (12.3 ± 1.9 to 18.7 ± 0.9 cmH2O;P < 0.01), Pop decreased (13.4 ± 1.9 to 6.0 ± 3.4 cmH2O;P < 0.01), and genioglossus electromyographic activity did not change (P > 0.05).Saline had no effect. These observations suggest that pharyngealintraluminal surface properties are important in maintaining pharyngealpatency. We propose that surfactants enhance pharyngeal patency byreducing surface tension and adhesive forces acting on intraluminal SAsurfaces. 相似文献
5.
Brown Robert H.; Mitzner Wayne; Wagner Elizabeth M. 《Journal of applied physiology》1997,83(2):366-370
Brown, Robert H., Wayne Mitzner, and Elizabeth M. Wagner.Interaction between airway edema and lung inflation onresponsiveness of individual airways in vivo. J. Appl.Physiol. 83(2): 366-370, 1997.Inflammatorychanges and airway wall thickening are suggested to cause increasedairway responsiveness in patients with asthma. In fivesheep, the dose-response relationships of individual airways weremeasured at different lung volumes to methacholine (MCh) before andafter wall thickening caused by the inflammatory mediator bradykininvia the bronchial artery. At 4 cmH2O transpulmonary pressure(Ptp), 5 µg/ml MCh constricted the airways to a maximum of 18 ± 3%. At 30 cmH2O Ptp, MCh resultedin less constriction (to 31 ± 5%). Bradykinin increased airwaywall area at 4 and 30 cmH2O Ptp(159 ± 6 and 152 ± 4%, respectively;P < 0.0001). At 4 cmH2O Ptp, bradykinin decreasedairway luminal area (13 ± 2%; P < 0.01), and the dose-response curve was significantly lower (P = 0.02). At 30 cmH2O, postbradykinin, the maximalairway narrowing was not significantly different (26 ± 5%;P = 0.76). Bradykinin produced substantial airway wall thickening and slight potentiation ofthe MCh-induced airway constriction at low lung volume. At high lung volume, bradykinin increased wall thickness but had no effecton the MCh-induced airway constriction. We conclude that inflammatoryfluid leakage in the airways cannot be a primary cause of airwayhyperresponsiveness. 相似文献
6.
Günther Zick Gunnar Elke Tobias Becher Dirk Sch?dler Sven Pulletz Sandra Freitag-Wolf Norbert Weiler Inéz Frerichs 《PloS one》2013,8(8)
Introduction
Lung-protective ventilation aims at using low tidal volumes (VT) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of VT and PEEP on ventilation distribution, regional respiratory system compliance (CRS), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation.Methods
EIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight VT and 5 cmH2O PEEP. After ALI induction, 10 ml/kg VT and 10 cmH2O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high VT ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional CRS and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high VT ventilation (6 and 10 (8) ml/kg) at three PEEP levels.Results
In healthy animals, high compared to low VT increased CRS and ventilation in dependent lung regions implying tidal recruitment. ALI reduced CRS and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH2O (mean±SD) resulted in comparable increase in CRS in dependent and decrease in non-dependent regions at both VT. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of VT. In patients, regional CRS differences between low and high VT revealed high degree of tidal recruitment and low overinflation at 3±1 cmH2O PEEP. Tidal recruitment decreased at 10±1 cmH2O and was further reduced at 15±2 cmH2O PEEP.Conclusions
Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional CRS. 相似文献7.
Hills; Brian A.; Piantadosi Claude A.; Huang Yuh-Chin Tony; Young Stephen L. 《Journal of applied physiology》1998,85(2):770-772
The following are the abstracts of the articles discussed inthe subsequent letter: Huang, Yuh-Chin T., Aneysa C. Sane, Steven G. Simonson, Thomas A. Fawcett, Richard E. Moon,Philip J. Fracica, Margaret G. Menache, Claude A. Piantadosi, andStephen L. Young. Artificial surfactant attenuates hyperoxic lunginjury in primates. I. Physiology and biochemistry. J. Appl.Physiol. 78(5): 1816-1822, 1995.Prolonged exposure toO2 causes diffuse alveolar damage and surfactantdysfunction that contribute to the pathophysiology of hyperoxic lunginjury. We hypothesized that exogenous surfactant would improve lungfunction during O2 exposure in primates. Sixteen healthymale baboons (10-15 kg) were anesthetized and mechanically ventilated for 96 h. The animals received either 100% O2(n = 6) or 100% O2 plus aerosolized artificialsurfactant (Exosurf; n = 5). A third group of animals(n = 5) was ventilated with an inspired fraction ofO2 of 0.21 to control for the effects of sedation andmechanical ventilation. Hemodynamic parameters were obtained every 12 h, and ventilation-perfusion distribution(A/) was measureddaily using a multiple inert-gas elimination technique. Positive end-expiratory pressure was kept at 2.5 cmH2O andwas intermittently raised to 10 cmH2O for 30 minto obtain additional measurements ofA/. After theexperiments, lungs were obtained for biochemical and histologicalassessment of injury. O2 exposures altered hemodynamics,progressively worsenedA/, altered lung phospholipid composition, and produced severe lung edema. Artificial surfactant therapy significantly increased disaturatedphosphatidylcholine in lavage fluid and improved intrapulmonary shunt,arterial PO2, and lung edema. Surfactant alsoenhanced the shunt-reducing effect of positive end-expiratory pressure.We conclude that an aerosolized protein-free surfactant decreased theprogression of pulmonary O2 toxicity in baboons. 相似文献
8.
Isoproterenol attenuates high vascular pressure-induced permeability increases in isolated rat lungs 总被引:6,自引:0,他引:6
Parker, James C., and Claire L. Ivey.Isoproterenol attenuates high vascular pressure-inducedpermeability increases in isolated rat lungs. J. Appl.Physiol. 83(6): 1962-1967, 1997.To separate thecontributions of cellular and basement membrane components of thealveolar capillary barrier to the increased microvascular permeabilityinduced by high pulmonary venous pressures (Ppv), we subjected isolatedrat lungs to increases in Ppv, which increased capillary filtrationcoefficient(Kfc) withoutsignificant hemorrhage (31 cmH2O)and with obvious extravasation of red blood cells (43 cmH2O). Isoproterenol (20 µM)was infused in one group (Iso) to identify a reversible cellularcomponent of injury, and residual blood volumes were measured to assessextravasation of red blood cells through ruptured basement membranes.In untreated lungs (High Ppv group),Kfc increased 6.2 ± 1.3 and 38.3 ± 15.2 times baseline during the 31 and 43 cmH2O Ppv states. In Iso lungs, Kfc was 36.2%(P < 0.05) and 64.3% of that in theHigh Ppv group at these Ppv states. Residual blood volumes calculatedfrom tissue hemoglobin contents were significantly increased by53-66% in the high Ppv groups, compared with low vascularpressure controls, but there was no significant difference between HighPpv and Iso groups. Thus isoproterenol significantly attenuatedvascular pressure-induced Kfc increases atmoderate Ppv, possibly because of an endothelial effect, but it did notaffect red cell extravasation at higher vascular pressures. 相似文献
9.
Phosphotyrosine phosphatase and tyrosine kinase inhibition modulate airway pressure-induced lung injury 总被引:3,自引:0,他引:3
We determinedwhether drugs which modulate the state of protein tyrosinephosphorylation could alter the threshold for high airwaypressure-induced microvascular injury in isolated perfused rat lungs.Lungs were ventilated for successive 30-min periods with peak inflationpressures (PIP) of 7, 20, 30, and 35 cmH2O followed by measurement ofthe capillary filtration coefficient (Kfc), asensitive index of hydraulic conductance. In untreated control lungs,Kfc increased by1.3- and 3.3-fold relative to baseline (7 cmH2O PIP) after ventilation with30 and 35 cmH2O PIP. However, inlungs treated with 100 µM phenylarsine oxide (a phosphotyrosinephosphatase inhibitor),Kfc increased by4.7- and 16.4-fold relative to baseline at these PIP values. In lungs treated with 50 µM genistein (a tyrosine kinase inhibitor),Kfc increasedsignificantly only at 35 cmH2OPIP, and the three groups were significantly different from each other.Thus phosphotyrosine phosphatase inhibition increased thesusceptibility of rat lungs to high-PIP injury, and tyrosine kinaseinhibition attenuated the injury relative to the high-PIP control lungs. 相似文献
10.
Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs 总被引:2,自引:0,他引:2
Kobayashi Tsutomu; Tashiro Katsumi; Yamamoto Ken; Nitta Shunichi; Ohmura Shigeo; Suzuki Yasuhiro 《Journal of applied physiology》1997,83(6):1849-1856
Kobayashi, Tsutomu, Katsumi Tashiro, Ken Yamamoto, ShunichiNitta, Shigeo Ohmura, and Yasuhiro Suzuki. Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs. J. Appl. Physiol. 83(6):1849-1856, 1997.To investigate the effects of surfactantproteins B (SP-B) and C (SP-C) on lung mechanics, we compared tidal andstatic lung volumes of immature rabbits anesthetized with pentobarbitalsodium and given reconstituted test surfactants (RTS).With a series of RTS having various SP-B concentrations (0-0.7%)but a fixed SP-C concentration (1.4%), both the tidal volume with25-cmH2O insufflation pressure and the static volume deflated to5-cmH2O airway pressure increased, significantly correlating with the SP-B concentration: the former increased from 6.5 to 26.0 ml/kg (mean), and the latter increased from6.4 to 31.8 ml/kg. With another series of RTS having afixed SP-B concentration (0.7%) but various SP-C concentrations(0-1.4%), the tidal volume increased from 5.1 to 24.8 ml/kg,significantly correlating with the SP-C concentration, whereas thestatic volume increased from 3.4 to 32.0 ml/kg, the ceiling value, inthe presence of a minimal concentration of SP-C (0.18%). Inconclusion, certain doses of SP-B and SP-C were indispensable foroptimizing dynamic lung mechanics; the static mechanics, however,required significantly less SP-C. 相似文献
11.
Wolfson Marla R.; Kechner Nancy E.; Roache Robert F.; Dechadarevian Jean-Pierre; Friss Helena E.; Rubenstein S. David; Shaffer Thomas H. 《Journal of applied physiology》1998,84(2):624-640
Wolfson, Marla R., Nancy E. Kechner, Robert F. Roache,Jean-Pierre DeChadarevian, Helena E. Friss, S. David Rubenstein, andThomas H. Shaffer. Perfluorochemical rescue after surfactant treatment: effect of perflubron dose and ventilatory frequency. J. Appl. Physiol. 84(2): 624-640, 1998.To test the hypotheses that perfluorochemical (PFC) liquidrescue after natural surfactant (SF) treatment would improve pulmonaryfunction and histology and that this profile would be influenced by PFCdose or ventilator strategy, anesthetized preterm lambs(n = 31) with respiratory distresswere studied using nonpreoxygenated perflubron. All animals received SFat 1 h and were randomized at 2 h as follows and studied to 4 h postnatal age: 1) conventionalmechanical gas ventilation (n = 8),2) 30 ml/kg perflubron with gasventilation [partial liquid ventilation (PLV)] at 60 breaths/min (n = 8),3) 10 ml/kg perflubron with PLV at60 breaths/min (n = 7), and4) 10 ml/kg perflubron with PLV at30 breaths/min (n = 8). All animalstolerated instillation without additional cardiopulmonary instability.All perflubron-rescued groups demonstrated sustained improvement in gasexchange, respiratory compliance, and reduction in pressure requirements relative to animals receiving SF alone. Improvement wasdirectly related to perflubron dose and breathing frequency; peakinspiratory pressure required to achieve physiological gas exchange waslower in the higher-dose and -frequency groups, and mean airwaypressure was lower in the lower-frequency group. Lung expansion wasgreater and evidence of barotrauma was less in the higher-dose and-frequency group; regional differences in expansion were not differentas a function of dose but were greater in the lower-frequency group.Regional differences in lung perflubron content were reduced in thehigher-dose and -frequency groups and greatest in the lower-dose and-frequency group. The results suggest that, whereas PLV of theSF-treated lung improves gas exchange and lung mechanics, theprotective benefits of perflubron in the lung may depend on dose andventilator strategy to optimize PFC distribution and minimize exposureof the alveolar-capillary membrane to a gas-liquid interface. 相似文献
12.
The effect of ventilation strategy on in vivo function of different surfactants was evaluated in preterm rabbits delivered at 27 days gestational age and ventilated with either 0 cmH2O positive end-expiratory pressure (PEEP) at tidal volumes of 10-11 ml/kg or 3 cmH2O PEEP at tidal volumes of 7-8 ml/kg after treatment with one of four different surfactants: sheep surfactant, the lipids of sheep surfactant stripped of protein (LH-20 lipid), Exosurf, and Survanta. The use of 3 cmH2O PEEP decreased pneumothoraces in all groups except for the sheep surfactant group where pneumothoraces increased (P < 0.01). Ventilatory pressures (peak pressures - PEEP) decreased more with the 3 cmH2O PEEP, low-tidal-volume ventilation strategy for Exosurf-, Survanta-, and sheep surfactant-treated rabbits (P < 0.05), whereas ventilation efficiency indexes (VEI) improved only for Survanta- and sheep surfactant-treated rabbits with 3 cmH2O PEEP (P < 0.01). Pressure-volume curves for sheep surfactant-treated rabbits were better than for all other treated groups (P < 0.01), although Exosurf and Survanta increased lung volumes above those in control rabbits (P < 0.05). The recovery of intravascular radiolabeled albumin in the lungs and alveolar washes was used as an indicator of pulmonary edema. Only Survanta and sheep surfactant decreased protein leaks in the absence of PEEP, whereas all treatments decreased labeled albumin recoveries when 3 cmH2O PEEP was used (P < 0.05). These experiments demonstrate that ventilation style will alter a number of measurements of surfactant function, and the effects differ for different surfactants. 相似文献
13.
Barnas George M.; Delaney Paul A.; Gheorghiu Ileana; Mandava Srinivas; Russell Robert G.; Kahn Renee; Mackenzie Colin F. 《Journal of applied physiology》1997,83(1):179-188
Barnas, George M., Paul A. Delaney, Ileana Gheorghiu,Srinivas Mandava, Robert G. Russell, Renée Kahn, and Colin F. Mackenzie. Respiratory impedances and acinar gas transfer in acanine model for emphysema. J. Appl.Physiol. 83(1): 179-188, 1997.We examined howthe changes in the acini caused by emphysema affected gas transfer outof the acinus (Taci) and lungand chest wall mechanical properties. Measurements were taken from fivedogs before and 3 mo after induction of severe bilateral emphysema byexposure to papain aerosol (170-350 mg/dose) for 4 consecutive wk.With the dogs anesthetized, paralyzed, and mechanically ventilated at0.2 Hz and 20 ml/kg, we measuredTaci by the rate of washout of133Xe from an area of the lungwith occluded blood flow. Measurements were repeated at positiveend-expiratory pressures (PEEP) of 10, 5, 15, 0, and 20 cmH2O. We also measured dynamicelastances and resistances of the lungs(EL andRL, respectively) and chest wall at the different PEEP and during sinusoidal forcing in the normal rangeof breathing frequency and tidal volume. After final measurements, tissue sections from five randomly selected areas of the lung eachshowed indications of emphysema.Taci during emphysema was similarto that in control dogs. ELdecreased by ~50% during emphysema (P < 0.05) but did not change itsdependence on frequency or tidal volume.RL did not change(P > 0.05) at the lowest frequencystudied (0.2 Hz), but in some dogs it increased compared with control at the higher frequencies. Chest wall properties were not changed byemphysema (P > 0.05). We suggestthat although large changes in acinar structure andEL occur during uncomplicatedbilateral emphysema, secondary complications must be present to causeseveral of the characteristic dysfunctions seen in patients withemphysema. 相似文献
14.
When airways constrict, the surrounding parenchyma undergoesstretch and distortion. Because of the mechanical interdependence between airways and parenchyma, the material properties of the parenchyma are important factors that modulate the degree ofbronchoconstriction. The purpose of this study was to investigate theeffect of changes in transpulmonary pressure (Ptp) and inducedconstriction on parenchymal bulk (k)and shear (µ) moduli. In excised rat lungs, pressure was measured atthe airway opening, and pressure-volume curves were obtained byimposing step decreases in volume with a calibrated syringe from totallung inflation. Calculation was made ofk during small-volume oscillations (1 Hz). Absolute lung volume at 0 cmH2O Ptp was obtained bysaline displacement. To calculate µ, a lung-indentation test wasperformed. The lung surface was deformed with a cylindrical punch(diameter = 0.45 cm) in 0.25-mm increments, and the force required toeffect this displacement was measured by a weight balance. Measurementsof k and µ were obtained at 4 and 10 cmH2O Ptp, and again at 4 cmH2O Ptp, after delivery ofmethacholine aerosol (100 mg/ml) into the trachea. Values ofk and µ in rat lungs were similar tothose reported in other species. In addition, k and µ were dependent on Ptp. Afterinduced constriction, k and µ increased significantly. That k and µ can increase after induced constriction has important implicationsvis a vis the factors modulating airway narrowing. 相似文献
15.
Hillman NH Nitsos I Berry C Pillow JJ Kallapur SG Jobe AH 《American journal of physiology. Lung cellular and molecular physiology》2011,301(5):L712-L720
The initiation of ventilation in preterm, surfactant-deficient sheep without positive end-expiratory pressure (PEEP) causes airway injury and lung inflammation. We hypothesized that PEEP and surfactant treatment would decrease the lung injury from initiation of ventilation with high tidal volumes. Fetal sheep at 128-day gestational age were randomized to ventilation with: 1) no PEEP, no surfactant; 2) 8-cmH(2)O PEEP, no surfactant; 3) no PEEP + surfactant; 4) 8-cmH(2)O PEEP + surfactant; or 5) control (2-cmH(2)O continuous positive airway pressure) (n = 6-7/group). After maternal anesthesia and hysterotomy, the head and chest were exteriorized, and the fetus was intubated. While maintaining placental circulation, the fetus was ventilated for 15 min with a tidal volume escalating to 15 ml/kg using heated, humidified, 100% nitrogen. The fetus then was returned to the uterus, and tissue was collected after 30 min for evaluation of early markers of lung injury. Lambs receiving both surfactant and PEEP had increased dynamic compliance, increased static lung volumes, and decreased total protein and heat shock proteins 70 and 60 in bronchoalveolar lavage fluid compared with other groups. Ventilation, independent of PEEP or surfactant, increased mRNA expression of acute phase response genes and proinflammatory cytokine mRNA in the lung tissue compared with controls. PEEP decreased mRNA for cytokines (2-fold) compared with groups receiving no PEEP. Surfactant administration further decreased some cytokine mRNAs and changed the distribution of early growth response protein-1 expression. The use of PEEP during initiation of ventilation at birth decreased early mediators of lung injury. Surfactant administration changed the distribution of injury and had a moderate additive protective effect. 相似文献
16.
Pandit Paresh B.; Pyon Kee H.; Courtney Sherry E.; England Sandra E.; Habib Robert H. 《Journal of applied physiology》2000,88(3):997-1005
Reported values of lung resistance(RL) and elastance (EL) in spontaneouslybreathing preterm neonates vary widely. We hypothesized that thisvariability in lung properties can be largely explained by both inter-and intrasubject variability in breathing pattern and demographics.Thirty-three neonates receiving nasal continuous positive airwaypressure [weight 606-1,792 g, gestational age (GA) of25-33 wk, 2-49 days old] were studied. Transpulmonary pressure was measured by esophageal manometry and airway flow by facemask pneumotachography. Breath-to-breath changes in RL andEL in each infant were estimated by Fourier analysis ofimpedance (Z) and by multiple linear regression (MLR).RLMLR (RLMLR = 0.85 × RLZ 0.43; r2 = 0.95) and ELMLR(ELMLR = 0.97 × ELZ + 8.4; r2 = 0.98) werehighly correlated to RLZ andELZ, respectively. Both RL(mean ± SD; RLZ = 70 ± 38, RLMLR = 59 ± 36 cmH2O · s · l1)and EL (ELZ = 434 ± 212, ELMLR = 436 ± 210 cmH2O/l)exhibited wide intra- and intersubject variability.Regardless of computation method, RL was found to decreaseas a function of weight, age, respiratory rate (RR), and tidal volume(VT) whereas it increased as a function ofRR · VT and inspiratory-to-expiratorytime ratio (TI/TE). EL decreasedwith increasing weight, age, VT and female gender andincreased as RR and TI/TE increased. Weconclude that accounting for the effects of breathing patternvariability and demographic parameters on estimates of RLand EL is essential if they are to be of clinical value.Multivariate statistical models of RL and ELmay facilitate the interpretation of lung mechanics measurements inspontaneously breathing infants. 相似文献
17.
In high-frequencyoscillatory ventilation (HFOV), an adequate mean airway pressure iscrucial for successful ventilation and optimal gas exchange, but airtrapping cannot be detected by the usual measurement at the y piece.Intratracheal pressures produced by the high-frequency oscillatorsHFV-Infantstar (IS), Babylog 8000 (BL), and the SensorMedics 3100A (SM)[the latter with either 30% (SM30) or 50%(SM50) inspiratory time] were investigated in fouranesthetized tracheotomized female piglets that were 1 day old andweighed 1.6-1.9 kg (mean 1.76 kg). The endotracheal tube wasrepeatedly clamped while the piglets were ventilated with anoscillation frequency of 10 Hz, and the airway pressure distal of theclamp was recorded as a measure of average intrapulmonary pressureduring oscillation. Clamping resulted in a significant decrease of meanairway pressure when the piglets were ventilated with SM30(0.86 cmH2O), BL (0.66 cmH2O), and IS(0.71 cmH2O), but airway pressure increased by a mean of0.76 cmH2O with SM50. Intratracheal pressure,when measured by a catheter pressure transducer at various oscillationfrequencies, was lower than at the y piece by 0.4-0.9cmH2O (SM30), 0.3-3 cmH2O(BL), and 1-4.7 cmH2O (IS) but was 0.4-0.7cmH2O higher with SM50. We conclude that theinspiratory-to-expiratory time(TI/TE) ratio influences theintratracheal and intrapulmonary pressures in HFOV and may sustain amean pressure gradient between the y piece and the trachea. ATI/TE ratio < 1:1 maybe useful to avoid air trapping when HFOV is used. 相似文献
18.
Julia C. Hartung Silke Wilitzki Marta Thio-Lluch Arjan B. te Pas Gerd Schmalisch Charles C. Roehr 《PloS one》2016,11(2)
Introduction
International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP.Methods
Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20cmH2O, VR 60/min, flow 8L/min. PEEP settings of 5 and 10cmH2O were studied. A second test was conducted with settings of PIP 40cmH2O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO2SMO+).Results
Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25th and 75th percentile) delivered PEEP with standard settings was 3.4(2.7–3.8)cmH2O when set to 5cmH2O and 6.1(4.9–7.1)cmH2O when set to 10cmH2O. Increasing the PIP from 20 to 40 cmH2O led to a median (25th and 75th percentile) decrease in PEEP to 2.3(1.8–2.7)cmH2O and 4.3(3.2–4.8)cmH2O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1–3.3)cmH2O and 5.0(3.5–6.2)cmH2O for both PEEP settings.Conclusion
Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates. 相似文献19.
Nagase Takahide; Aoki Tomoko; Oka Teruaki; Fukuchi Yoshinosuke; Ouchi Yasuyoshi 《Journal of applied physiology》1997,83(1):46-51
Nagase, Takahide, Tomoko Aoki, Teruaki Oka, YoshinosukeFukuchi, and Yasuyoshi Ouchi. ET-1-induced bronchoconstriction ismediated via ETB receptor in mice.J. Appl. Physiol. 83(1): 46-51, 1997.Endothelin (ET)-1 is one of the most potent agonists of airwaysmooth muscle and can act via two different ET receptor subtypes, i.e.,ETA andETB. To determine the effects ofET-1 on in vivo pulmonary function and which ET receptors are involved in murine lungs, we investigated 1)the effects of ET and sarafotoxin S6c (S6c), a selectiveETB agonist, on pulmonary functionand 2) the effects of BQ-123 andBQ-788, specific ETA- andETB-receptor antagonists, onET-1-induced bronchoconstriction. ICR mice were anesthetized and mechanically ventilated (frequency = 2.5 Hz, tidalvolume = 8 ml/kg, positive end-expiratory pressure = 3 cmH2O). Intravenous ET-1, ET-2,and ET-3 increased lung resistance similarly and equipotently, whereasS6c elicited a greater degree of bronchoconstriction. Mice were thenpretreated with saline (Sal), BQ-123 (0.2, 1, and 5 mg/kg), or BQ-788(0.2, 1, and 5 mg/kg) before administration of ET-1(107 mol/kg iv). No dose ofBQ-123 blocked ET-1-induced constriction, whereas pretreatment witheach dose of BQ-788 significantly inhibited ET-1-induced responses.There were significant differences in morphometrically assessed airwayconstriction between Sal and BQ-788 and between BQ-123 and BQ-788,whereas no significant difference was observed between Sal and BQ-123.There were no significant morphometric differences in the airway wallarea among the three groups. These observations suggest that theETB- but notETA-receptor subtype may mediatethe changes in murine pulmonary function in response to ET-1. Inaddition, the ETB-receptorantagonist reduces ET-1-induced airway narrowing by affecting airwaysmooth muscle contraction in mice. 相似文献
20.
Jerome E. Heidi; Enzan Keiji; Douguet Dominique; Lei Dachuan; Jesmok Gary; Johnson Carol W.; Neuburger Maritza; Staub Norman C. 《Journal of applied physiology》1996,81(4):1730-1738
Jerome, E. Heidi, Keiji Enzan, Dominique Douguet, DachuanLei, Gary Jesmok, Carol W. Johnson, Maritza Neuburger, and Norman C. Staub. Chronic interleukin-2 treatment in awake sheep causes minimal or no injury to the lung microvascular barrier.J. Appl. Physiol. 81(4):1730-1738, 1996.Interleukin-2 (IL-2) is reputed tocause a "vascular leak syndrome." We studied pulmonaryhemodynamics and lymph dynamics in six sheep treated for 7 days withIL-2 (1.8 million IU/kg twice daily or 1.8 million IU/kg each day as acontinuous infusion). Lung lymph flow increased from 4.8 ± 2 ml/15min pre-IL-2 to 14.4 ± 6.8 ml/15 min on the seventh day of IL-2.The lymph-to-plasma protein concentration ratio was unchanged (0.70 ± 0.06 vs. 0.63 ± 0.13). The plasma-to-lymph equilibrationhalf-time of radiolabeled albumin was 2.0 ± 0.6 h pre-IL-2 and 1.0 ± 0.7 h on day 7 of IL-2. Pulmonary arterial pressure was 24 ± 7 cmH2O pre-IL-2, increased to 32 ± 4 cmH2O on the fourth day ofIL-2, and returned to 29 ± 5 cmH2O on the seventh day of IL-2.Extravascular lung water was normal (4.07 ± 0.25 g/g dry lung). Toclearly determine whether the increase in lung lymph flow was due tohemodynamic changes or to increased leakiness of the microvascularbarrier, we volume loaded six sheep with lactated Ringer solutionbefore and after 3 days of IL-2 treatment (1.8 million IU/kg twicedaily). Lung lymph flows increased fivefold during 4 h of crystalloidinfusion compared with baseline and were higher after 3 days of IL-2.However, lymph-to-plasma protein concentration ratios decreased to the same low levels pre- and post-IL-2 (0.39 ± 0.06 vs. 0.41 ± 0.10), indicating an intact microvascular barrier. Extravascular lung water was elevated (5.56 ± 0.39 g/g dry lung) but was not different from lung water in three volume-loaded control sheep (4.87 ± 0.53 g/g dry lung). We conclude that IL-2 causes minimal or no injury to thepulmonary microvascular barrier and that volume expansion during IL-2treatment can cause hydrostatic pulmonary edema. 相似文献