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Biomedical subjects

B Lachmann

Publications and source records attributed to B Lachmann.

At least 181 records · Page 10Linked to original sources
PubMed1982

Combined effects of surfactant substitution and prolongation of inspiration phase in artificially ventilated premature newborn rabbits.

Premature newborn rabbits, delivered by hysterotomy on day 27 of gestation, were tracheotomized at birth, kept in body plethysmographs, and subjected to pressure-generated ventilation at a working pressure of 25 cm H2O, 100% O2, and frequency 40/min. Thirty-seven animals received 50 microliters of heterologous surfactant (phospholipid content 40 mg/ml) via the tracheal cannula before onset of artificial ventilation, eight were ventilated with a positive end-expiratory pressure (PEEP) of 6 cm H2O, and 44 served as controls. All animals were ventilated in a randomized sequence of 2-min periods with 20, 40, 60, or 80% inspiration time. After the experiment the trachea was clamped at end-inspiration and the lungs fixed by immersion in formalin. Plethysmograph recordings of tidal volume revealed that lung-thorax compliance was low in control animals, even at inspiration time 80% (mean +/- S.E. = 0.17 +/- 0.03 ml/cm H2O X kg). In animals treated with surfactant or PEEP, compliance was significantly improved at all ventilator settings. The highest mean compliance values, obtained at 60% inspiration time were 0.91 +/- 0.07 and 0.73 +/- 0.14 ml/cm H2O X kg in surfactant- and PEEP-treated animals, respectively. Compliance of surfactant-treated animals was significantly higher than that of PEEP-treated animals at inspiration time 40% (0.85 +/- 0.07 versus 0.52 +/- 0.13 ml/cm H2O X kg; P less than 0.05). The relative volume of the alveolar compartment, determined morphometrically in histologic sections and expressed as the alveolar expansion index (Ia), was significantly higher in surfactant-treated animals than in controls (1.60 +/- 0.12 versus 0.74 +/- 0.06; P less than 0.005), but not improved in animals ventilated with PEEP. In animals receiving surfactant, Ia increased with the duration of the inspiration phase, from 0.99 +/- 0.10 at 20% to 1.95 +/- 0.22 at 80% inspiration time. There was also histologic evidence of enhanced recruitment of aerated alveoli in surfactant-treated animals ventilated with prolonged inspiration time.

Animals↗
PubMed1982

[The effect of intermittent hydrogen chloride exposure on the lung function of the guinea pig].

23 guinea pigs were exposed to 15 mg/m3 HCl gas 5 days/week, 2 hours daily, for 7 weeks. 15 animals served as controls. From the 5th day of exposure, the following lung function parameters were evaluated in anaesthetised animals: VT, fR, minute volume, TGV, Vmax, R1, Rw, Rrs, Cl, Cw, Crs, delta Poes/VT, hemoglobin, SaO2, PaO2, PaCO2, pH, SBC, BE. These measurements showed no differences between HCl-exposed animals and controls. Histological examination of the lungs revealed no changes which could be attributed to HCl-exposure. This study relates to the important question whether lung damage can be induced by industrially produced, intermittent high levels of HCl in the environment.

Animals↗
PubMed1982

The antenatal use of ambroxol (bromhexine metabolite VIII) to prevent hyaline membrane disease: a controlled double-blind study.

A prospective double-blind clinical trial was carried out to determine whether ambroxol (bromhexine metabolite VIII) treatment (1000 mg/day for a period of 5 days) reduces the risk of hyaline membrane disease (HMD) in potentially premature infants. Amniocentesis was performed before the first and 24 h after the last application of ambroxol or placebo to assess the development of the total phospholipid phosphorus content, the L/S ratio, the P/S ratio, and the properties of the surface tension of the amniotic fluid after ambroxol or placebo. There were 246 infants born to 224 mothers. Of the 116 infants with less than or equal to 36 completed weeks' gestation, 56 were in the ambroxol and 60 in the placebo group. No differences between groups occurred in risk factors for HMD (diabetes, asphyxia, male sex, cesarean section). Statistically significant differences in favor of the infants in the ambroxol group were found in the HMD incidence: 23.2% in the ambroxol group compared with 41.7% in the placebo group (p less than 0.05). There was no reduction of the HMD incidence in the less than or equal to 32-week gestational age category in the ambroxol group compared with the placebo group inspite of the fact that all the examined parameters for determining lung maturity reflected a stimulatory effect of ambroxol compared with the results of the placebo group, particularly before the 33rd week of gestation. Prolonged rupture of the membranes played no protective role against HMD.

Ambroxol↗
PubMed1982

[Complex airway resistance as a means of characterizing the strength of asthmatic reaction in the guinea pig].

45 guinea pigs sensitized to ovalbumin and 9 controls were challenged with antigenic aerosol. Before and during the challenge oesophageal pressure (Poes), airflow (V) and tidal volume (VT) were measured in anaesthetized (urethane) spontaneously breathing animals. Inspiratory and expiratory lung resistance (RI, RE) and dynamic lung compliance (Cdyn) were obtained according to the method of Neergard and Wirz. Total pulmonary resistance was calculated by different methods. 18 animals responded with a significant asthmatic reaction with an increase of expiratory resistance and a decrease of dynamic compliance. There exists a close hyperbolic relation between RE and Cdyn before and during the asthmatic reaction. The best parameter to characterize the strength of asthmatic response in the anaesthetized guinea pig is delta Poes/VT.

Airway Resistance↗
PubMed1981

Effect of supplementary surfactant on in vivo lung mechanics in the premature rabbit neonate.

Premature newborn rabbits, delivered on day 27 of gestation, were subjected to positive-pressure ventilation, with or without treatment with natural surfactant. The surfactant, obtained by centrifugation of lung wash from adult rabbits, was deposited in the tracheal cannula before the onset of ventilation. Parameters of lung mechanisms, recorded during spontaneous ventilation after 1 h, were significantly improved in animals receiving surfactant. In comparison with littermate controls, surfactant-treated animals also had less prominent bronchiolar epithelial lesions. We conclude that treatment with supplementary surfactant facilitates functional adaptation of the premature lung and prevents the development of epithelial lung lesions during artificial ventilation.

Animals↗
PubMed1981

Lung compliance and alveolar expansion in the artificially ventilated premature newborn rabbit after maternal treatment with ambroxol.

Premature newborn rabbits were delivered on day 27 of gestation, with or without antenatal treatment with ambroxol (50 mg/kg/day in maternal injections, on days 24-26). The animals were tracheostomized, kept in body plethysmographs at 35 degrees C, and ventilated artificially for 10 min with 100% oxygen, insufflation pressure 30 cm H2O, frequency 40/min, and varying inspiration time (20, 40, 60, or 80%). Lung-thorax compliance increased with inspiration time in both ambroxol-treated animals and controls, but there was no difference in compliance between treated and non-treated litters. Alveolar expansion, evaluated morphometrically in histological sections, was enhanced in ambroxol-treated animals ventilated with prolonged inspiration phase (60 or 80%); such a difference was not found in the on-treated group. This suggests that antenatal treatment with ambroxol might have a stimulating effect on the synthesis and/or release of factors improving alveolar stability in the premature lung.

Ambroxol↗
PubMed1981

Lung-thorax compliance in the artificially ventilated premature rabbit neonate in relation to variations in inspiration:expiration ratio.

Surfactant-deficient premature newborn rabbits obtained by hysterotomy on day 27 of gestation were tracheostomized at birth, kept in a multichambered pressure-constant body plethysmograph, and subjected to intermittent positive pressure ventilation using a standardized insufflation pressure (30 cm H2O). A sequence of various frequencies (20, 40, and 60/min) and inspiration:expiration (I:E) ratios (1:4, 1:2, 1:1, 2:1, and 4:1) were applied, and the effect of these various respirator settings on tidal volume (VT) and flow was evaluated by means of a Fleisch tube connected to the body plethysmograph. Irrespective of respirator frequency, increasing I:E ratio from the basic setting of 1:1 resulted in increased VT; decreasing I:E ratio had the opposite effect. There was a nearly linear relation between variations in I:E ratio and VT, but the slope of the regression line was steeper at frequencies 40 and 60/min than at 20/min. At a frequency of 20/min, values (X +/- S.D.) for lung-thorax compliance at I:E ratios of 1:4 and 4:1 were 0.50 +/- 0.26 and 0.99 +/- 0.42 ml/cm H2O.kg, respectively. Corresponding figures for frequency of 60/min were 0.21 +/- 0.10 and 0.73 +/- 0.36 ml/cm H2O.kg. At the two higher frequencies and low I:E ratios (less than or equal to 1:1), the duration of the inspiration phase was not sufficient to provide the maximal degree of lung expansion attainable with this insufflation pressure under static conditions. At frequency of 60/min and I:E ratio of 4:1, the expiration was short enough to prevent zero flow before onset of inspiration.

Animals↗
PubMed1981

[Results of studies on dogs after unilateral allogeneic lung transplantation without immunosuppression].

The observations and the results after allogenic lung transplantation in 24 receivers were reported. The animals were not treated immuno-suppressively. They survived 6.2 days on an average and died in consequence of the rejection. The transplant is progressively threatened of bacterial infections after the beginning of the rejection even in case of an operation under sterile conditions. The investigations confirmed a narrow correlation between the leucocyte count and the course of the rejection. However, the condition of the transplant can be estimated approximately certainly by means of complex clinical methods of examination.

Animals↗
PubMed1980

The effect of cytidine diphosphate choline on in vivo lung mechanics in premature newborn rabbits.

The influence of CDP-choline on neonatal lung adaptation was studied in premature rabbit neonates, delivered on day 28 of gestation. We found that the administration of CDP-choline (200 mg/kg body wt) at birth has a moderately beneficial effect on the respiratory frequency, dynamic lung compliance, and expiratory lung resistance. Since this effect was obtained within 60 min, and since the phospholipid content of the alveolar wash was similar on experimental and control animals, we concluded that the observed improvement in lung mechanics was probably not mediated by increased synthesis or release of surfactant phospholipids.

Animals↗
PubMed1980

In vivo lung lavage as an experimental model of the respiratory distress syndrome.

Using adult guinea-pigs, we have developed an experimental model in which alveolar surfactant phospholipids are removed by repeated lung lavage in vivo, and in which the short-term survival of the animals is ensured by artificial ventilation. Blood gases, parameters of lung mechanics, and histologic and electron microscopic findings indicate that the lavage procedure induces a condition similar to the adult respiratory distress syndrome. We propose that our technique might be used for evaluation of pharmacological agents and various forms of artificial ventilation which have been suggested for treatment of this disease.

Animals↗
PubMed1980

Artificial surfactant and natural surfactant. Comparative study of the effects on premature rabbit lungs.

Premature newborn rabbits, delivered on day 27 of gestation, were treated with tracheal deposition of dry artificial surfactant containing dipalmitoyl phosphatidylcholine and unsaturated phosphatidylglycerol (7:3), or crude natural surfactant prepared by centrifugation of lung wash from adult rabbits. Before receiving surfactant, the animals were allowed to breathe for 7--27 min; they were then subjected to artificial ventilation under standardised conditions. In comparison with littermate controls, both groups of surfactant-treated animals showed statistically significant improvement in lung-compliance 30 and 60 min after onset of ventilation. However, necrosis of bronchiolar epithelium and hyaline membranes was present in nearly all animals, even in those treated with natural surfactant; this suggests that in order to prevent epithelial lesions, surfactant should be given as soon as possible and preferably at birth. Our findings confirm earlier observations that treatment with supplementary surfactant has a beneficial effect on lung mechanics in the premature neonate. The fact that this effect can be obtained not only with natural surfactant but also with dry artificial surfactant should increase the possibility of clinical application.

Animals↗
PubMed1980

Application of bromhexine metabolite VIII (NA 872) and bromhexine-glucose in treatment of adult respiratory distress syndrome; experimental and clinical results .

The authors study the changes in cardiopulmonary function after application of bromhexine metabolite VIII (NA 872) in an animal model of adult respiratory distress syndrome (ARDS) and bromhexine glucose solution (BGS) in ARDS patients. After damage of the lung alveolar surfactant by intratracheal atomization of 0.2 M HCl in LEWE Minipigs significant changes in lung compliance, dead space ventilation, venous admixture, alveolo-arterial oxygen tension difference, pulmonary vascular resistance, and oxygen uptake are present under application of NA 872 in comparison to untreated animals. In ARDS patients treated with BGS, pulmonary function is significantly ameliorated indicated by changes in static effective compliance, oxygen exchange ratio, and alveolo-arterial oxygen tension difference.

Animals↗
PubMed1979

Lung mechanics during spontaneous ventilation in premature and fullterm rabbit neonates.

Rabbit neonates were tracheotomized on day 27--30 of gestation, and lung mechanics during spontaneous ventilation was registered with a fluid-filled esophagus catheter for pressure recording and a pneumotachograph connected to the tracheal cannula via a Fleisch tube. The first breath of all neonates had a very long inspiratory phase (less than or equal to 1.12 sec), with insufflation pressures amounting to 42 cm H2O in the mature animals. The expiration phase of the first breath was usually 'passive', i.e. there was no positive expiratory esophagus pressure. In animals delivered on day 27--28 there was, as a rule, no difference between inspiratory and expiratory tidal volume during the first few breaths, whereas such difference was regularly registered in mature animals; this phenomenon probably corresponds to the establishment of FRC. Dynamic lung compliance increased with both gestational and postnatal age, up to 60 min after delivery. Shortly after birth, pulmonary resistance was higher in immature animals than in fullterm ones, but at later intervals, there was no difference between survivors of various gestational age.

Animals↗
PubMed1977

[Morphological studies of experimental lung transplantation. I. Light microscopic and histochemical findings in autotransplants of dog lungs].

Morphological investigations (light microscopy, semithin sections, histochemistry) on autografted lungs showed two changes with mifferent regional distributions. In the upper lobes were found focal areas of slight fibrosis, in the upper and lower lobes degenerative changes especially of the small bronchi and bronchioles with a focal loss of activity of alkaline phosphatase, nonspecific esterase and some dehydrogenase. Possible reasons for these morphological changes are discussed in connection with functional and biochemical results.

Acid Phosphatase↗
PubMed1976

[Comparison of lung-mechanical and physico-chemical Parameters in view of the pulmonary surfactant system (author's transl)].

Evaluation of static pressure-volume-diagram of lungs and of surface-tension-area-diagram of lung-elutions measured on the Lamgmuir-balance is tested. Well known parameters are used to characterize alveolar surfactant activity in guinea pigs after perbronchial application of extracorporal surfactant Tacholiquin and detergent "Fit" 1% and after application of vagomimetics Acetylcholine 1% and Histamine 0.1%. Mean values of physico-chemical parameters show the most significant increase of the area of hysteresis (Benzer) during Tacholiquin and Acetylcholin application; the minimal surface-tension: gamma min, and the compressibility-index: gamma min/delta gamma (Kötter, Rüffer) decreased, the difference between maximal and minimal surface-tension: delta gamma and the stability-index: 2 delta gamma/(gamma max + gamma min) (Clements) increased. Tacholiquin and Acetylcholin both improve pulmonary surface-activity. The Tacholiquin-effect is documented in lung mechanics only by elevation of the inspiratory volume-rations: V10I/V20I (Clements) and V10I/Vmax (Kittelmann) referred to static pressure 10, 20 cm H2O and maximal pressure but not by elevation of the expiratory stability index V10E/Vmax (Gruenwald). The area of hysteresis is decreased indicating a preponderant inspiratory effect. The Acteylcholin-effect is covered by the well-known bronchial obstructive effect. Both inspiratory constants are decreased, and the area of hysteresis is increased. We did not find any significance of the expiratory stability index. Both inspiratory constants and the area of hysteresis are conditional surfactant parameters in view of bronchial obstruction.

Acetylcholine↗
PubMed1976

[Functional analysis in experimental respiratory distress syndrome (author's transl)].

After injection of an anti-lung -serum a respiratory distress syndrome could be produced in spontaneously-breathing guinea pigs. Reduced compliance, increased resistance and work of breathing was found. Morphological investigations showed intraalveolar and interstitial bleedings and a lung edema. Biochemically a decreased total phospholipid content could be found. Surface tension characteristics, examined with the Langmuir balance, were deteriorated. A complete restitution of surface tension parameters and total phospholipid content was obtained by administration of bromhexin metabolit Na 872.

Animals↗