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Biomedical subjects

N González Mangado

Publications and source records attributed to N González Mangado.

18 recordsLinked to original sources
PubMed2003

[Reliability of Venturi oxygen therapy systems].

Venturi systems are among the most widely used devices for delivering oxygen therapy. Nevertheless, rigorous quality control of their reliability is lacking. In this study we used mass spectrometry to evaluate Venturi systems sold by various companies in Spain. We also studied tolerance under various conditions (changes in oxygen flow and with increased system resistance). Fixed systems were found to comply well with recommendations, whereas none of the variable systems complied. One system (Oxigem Variable) was unable to provide an oxygen concentration below 31% when set to deliver at 24% to 28%. We conclude that the variable masks available in Spain do not comply with European Union recommendations and the range of error of one of them (Oxigem Variable) means it is not clinically useful. Fixed systems were the most reliable ones in our market, and airlife and intersurgical devices were the variable systems that best approximated the reliability of fixed systems.

Equipment Safety↗
PubMed2002

Similar ventilation distribution in normal subjects prone and supine during tidal breathing.

Multiple-breath washout (MBW) tests, with end-expiratory lung volume at functional residual capacity (FRC) and 90% O(2), 5% He, and 5% SF(6) as an inspired gas mixture, were performed in healthy volunteers in supine and prone postures. The semilog plot of MBW N(2) concentrations was evaluated in terms of its curvilinearity. The MBW N(2) normalized slope analysis yielded indexes of acinar and conductive ventilation heterogeneity (Verbanck S, Schuermans D, Van Muylem A, Paiva M, Noppen M, and Vincken W. J App Physiol 83: 1907-1916, 1997). Also, the difference between SF(6) and He normalized phase III slopes was computed in the first MBW expiration. Only MBW tests with similar FRC in the prone and supine postures (P > 0.1; n = 8) were considered. Prone and supine postures did not reveal any significant differences in curvilinearity, N(2) normalized slope-derived indexes of conductive or acinar ventilation heterogeneity, nor SF(6)-He normalized phase III slope difference in the first MBW expiration (P > 0.1 for all). The absence of significant changes in any of the MBW indexes suggests that ventilation heterogeneity is similar in the supine and prone postures of normal subjects breathing near FRC.

Adult↗
PubMed2000

N-acetylcysteine prevents cigarette smoke induced small airways alterations in rats.

This study investigated the effect of cigarette smoke exposure and the potential protection N-acetylcysteine (NAC) in rat lungs. Forty-eight rats were exposed to cigarette smoke (CS) for 10 weeks, without (CS group) or with (CS+NAC group) oral intake of NAC 200 mg x rat(-1) x day(-1), or to fresh air (Control). All rat lungs were assessed in terms of lung function, ventilation distribution (nitrogen, helium and sulphur hexafluoride phase III slopes), and morphometry (airway wall thickening of small, medium and large bronchi). The small bronchi, defined as the airways with an internal perimeter <1,000 microm showed significantly thicker airway walls in the CS than in the Control group. By contrast, no airway wall thickening was observed in the CS+NAC group with respect to Control. Except for decreased lung volumes and compliance in CS and CS+NAC groups, which were entirely attributable to smaller body weight gain, lung function was indistinguishable from Control. Phase III slopes were significantly increased only in the CS group. In conclusion, smoke-induced alterations in the rat lungs were reflected in wall thickening of the small bronchi and increased ventilation maldistribution. These smoke-induced morphometric and ventilation distribution alterations were prevented by N-acetylcysteine.

Acetylcysteine↗
PubMed1998

Intrapulmonary gas mixing in panacinar- and centriacinar-induced emphysema in rats.

We studied ventilation distribution using the single-breath washout technique in rats with two types of induced emphysema: panacinar-like (by instilled elastase) and centriacinar-like (by inhaled CdCl2 combined with oral intake of beta-aminopropionitrile). Morphologically, panacinar and centriacinar groups presented a similar degree of airspace enlargement, which was irregularly distributed and also accompanied by fibrosis only in the centriacinar group. In terms of mechanical properties, the centriacinar group presented lower end-expiratory flows and lower compliance than the panacinar group. The ventilation distribution patterns were also different between both groups. Single-breath washout phase III slopes, reflecting mainly diffusion-convection-dependent inhomogeneities in rat lungs, were largest in the centriacinar group. The SF6-He slope difference, which was reversed in both emphysema groups with respect to the control group, could be attributed mainly to He slope changes in the panacinar group and to SF6 slope changes in the centriacinar group. In addition, the respective He and SF6 slope decrease as a function of end-inspiratory breath-hold time, was only different from the control group in the centriacinar group. The observed ventilation distribution patterns can be explained by interacinar elastic changes in the panacinar group and severe interacinar structural alterations in the centriacinar group.

Administration, Inhalation↗
PubMed1991

Multiple-breath washout experiments in rat lungs.

Multiple-breath washouts were performed on 30 Wistar rats postmortem in a study in which breaths of 90% O2-5% He-5% SF6 were given. Preliminary comparison of alveolar plateau slopes obtained from anesthetized rats in vivo and postmortem showed that ventilation distribution remains the same within 1 h after the animals were killed. For maneuvers with different preinspiratory lung volumes and end-inspiratory breathholding, we computed the normalized N2 slope (Sn) and Fowler and Bohr dead spaces [VDF(n) and VDB(n), respectively] as a function of breath number (n). For all maneuvers analyzed, Sn of all gases increased in the first two or three breaths and reached a horizontal asymptote thereafter. The value of Sn decreased, both with increasing preinspiratory lung volume and breath hold of 4 s. The fact that the horizontal Sn asymptote is reached after only two or three breaths suggests the absence of convection-dependent inhomogeneities (CDI) in rat lungs. This contrasts with multiple-breath washout experiments in humans, where interregional (gravity-dependent CDI) and intraregional CDI generate a marked increase in Sn throughout the entire washout. Also, in contrast with results in humans, VDF and VDB were independent of n. The present work suggests that rats may be used to study diffusion- and convection-dependent inhomogeneities without the influence of CDI or gas exchange.

Animals↗
PubMed1991

Single-breath washout experiments in rat lungs.

Single-breath washouts were performed on 30 Wistar rats postmortem in studies in which breaths of 90% O2-5% He-5% SF6 were given. We investigated the effects of variations in preinspiratory lung volume, inspired volume, end-inspiratory breath-hold time, and inspiratory and expiratory flows on the alveolar plateau slopes for N2, He, and SF6. The main result is that the slope for He was always larger than the slope for SF6, except for large breath-hold times (approximately 15 s), contrary to previous findings in other species. Slopes for the three gases decreased with increasing inspiratory and expiratory flows when flows were greater than 1 ml/s. There was a strong correlation between the magnitude of a slope and its curvilinearity, suggesting that the concentration heterogeneity in the lung that causes the slope is due to interaction between diffusion and convection. The results seem incompatible with heterogeneities of parenchymal elasticity, which have been said to contribute to alveolar slopes in dog lungs but appear to be completely explainable as the result of diffusion-convection interaction in an asymmetric lung structure that has acini widely spread along the tracheobronchial tree.

Animals↗
PubMed1990

Effects of inspiratory and expiratory time and high mouth pressures on calculated DLCO by the single-breath procedure. Results with different methods to measure the effective breath-holding time.

We have studied the influence of several manoeuvres modifying inspiratory and expiratory flow, with and without an external obstruction, on measured single-breath diffusing capacity (DLCO). By this method, we could evaluate the effects of increased inspiration or expiration time, independently of the influence of high (negative or positive) mouth pressures. Ten tests were performed in each of 11 trained normal subjects. The sequence of repeated manoeuvres was as follows: (1) basal; (2) inspiratory obstruction (IO); (3) expiratory obstruction (EO); (4) slow inspiration without obstruction (SI), and (5), slow expiration without obstruction (SE). A second, inverted sequence was then performed. The obstructive manoeuvres were forced by a unidirectional valve with a circular hole of 5 mm in diameter. Mouth pressures were registered. The slow flows were voluntarily controlled to be similar to the corresponding flows during the obstructive manoeuvre (approximately 15% of each vital capacity/second). Determinations of breath-holding time (tBH) were calculated by the methods of Jones-Meade, Ogilvie and the American Epidemiology Standardization Project (ESP), but using the same expiratory sample. We found that (DLCO) obtained with the three methods were statistically different (p less than 0.0001) from each other for all manoeuvres. Regarding the basal manoeuvre, there were statistical differences (p less than 0.01) with SI on the Jones-Meade, with IO on the ESP and with SI and IO on the Ogilvie timing methods. Between IO and SI, statistical differences (p less than 0.01) were observed in the three methods, but there was no statistical difference between SE and EO by any method.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1987

A simple method of correcting diffusing capacity for alveolar volume reduction in restrictive lung diseases.

We studied the discriminative power of the transfer factor (TLCO), KCO (TLCO/Va) and ZCO (a corrected TLCO according to alveolar volume measured (Va), introduced by our group), in order to differentiate diffuse interstitial disease from other restrictive diseases. Measurements were taken in 46 subjects, divided into two groups: Pure restriction (group 1: normal subjects with voluntary restriction and diseased subjects) and (2) diffuse interstitial restriction (group 2). There were no statistical differences in Va between groups 1 and 2. TLCO was statistically lower in groups 1 and 2 in comparison with the control group (normal values of our laboratory in test with Va greater than 90% of predicted) and showed a significant difference when group 1 was compared with group 2. Similar results (but with higher values than those of the control group) were found for KCO. A similar difference exists in ZCO only when group 2 is compared with group 1, but not when group 1 is compared with the control group. The corrected diffusion capacity ZCO yields the highest discriminative power.

Humans↗
PubMed1987

Pulmonary ceroidosis.

We describe a patient with pulmonary ceroid histiocytosis. Skin pigmentation, chest x-ray film and laboratory findings were normal. Only pulmonary function tests were abnormal (TLC = 63 percent, DLco = 52 percent). Based on these functional data, the patient was submitted to a lung biopsy by thoracotomy. Brown pigmented histiocytes were shown occupying alveolar spaces. Similar brown pigmented hepatocytes were seen in the liver biopsy.

Adult↗
PubMed1986

Pulmonary parenchymal tissue volume and pulmonary capillary blood flow in normal subjects.

We measured pulmonary parenchymal tissue volume (Vt) and pulmonary capillary blood flow (Qc) in 11 normal subjects by a rebreathing technique and end-tidal, dead-space correction (ETDS) method, using two soluble gases, acetylene (C2H2) and dimethyl ether (DME). We assessed the results using different intervals of measurement, inspired volumes and rebreathing frequencies. The mean values +/- SD of Vt were 559 +/- 58 and 511 +/- 52 ml, with C2H2 and DME, and of Qc were 3.67 +/- 0.44 and 4.18 +/- 0.54 liter/min/m2, respectively. Measurements with the interval between the 1st and the 6th end-tidal points and within the first 15 s yielded the best reproducibility. Data obtained from two satisfactory recordings from the same subject are sufficient to calculate Vt and Qc. Inspired volume shows a significant correlation with Vt values measured with both tracer gases, especially with DME. Rebreathing frequency also affects this latter gas. Despite some problems which are not easily explainable (dependence upon the inspired volume, rebreathing frequency and test gas species), we conclude that the methods allow measurements of Vt and Qc with acceptable reproducibility but that different variables may affect the results.

Adult↗