Effects of resistive loading on breathing variability non linear analysis and modelling approaches.
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Humans↗
Biomedical subjects
G Benchetrit
Publications and source records attributed to G Benchetrit.
Anti-HPA-1a-mediated platelet phagocytosis by monocytes in vitro and its inhibition by Fc gamma receptor (FcgammaR) reactive reagents.
The study was undertaken to delineate mechanisms of platelet destruction by phagocytosis during fetal/neonatal alloimmune thrombocytopenia (FAIT/NAIT) because of maternal antibodies against human platelet antigen 1a (HPA-1a). By employing a platelet phagocytosis assay based on the ORPEGEN flow cytometric bacterial phagocytosis test, we measured monocyte ingestion of platelets mediated by anti-HPA-1a antibodies. Moreover, we tested, as potential therapeutic agents, FcgammaR reactive reagents, for their inhibition of this process. Four of six anti-HPA-1a sera tested mediated phagocytosis of HPA-1a-positive platelets in a concentration-dependent manner. Monocyte ingestion of platelets was almost completely inhibited by cytochalasin D. No anti-HPA-1a-mediated phagocytosis was observed with anti-HPA-1a-negative platelets. The humanised anti-FcgammaRI monoclonal antibody H22 at concentrations 1-100 microg/ml, completely inhibited anti-HPA-1a-mediated phagocytosis as did similar concentrations of ivIg. By contrast, a mouse monoclonal anti-FcgammaRII (IV.3, Fab) at 10 microg/ml caused little or no suppression of platelet phagocytosis mediated by two anti-HPA-1 sera. Furthermore, the addition of anti-FcgammaRII (10 microg/ml) to sub-optimal concentrations of H22 did not significantly increase the inhibitory effect of the latter compound. Monomeric IgG (0.1-10 microg/ml) failed to suppress anti-HPA-1 mediated platelet ingestion by the phagocytes, as did anti-FcgammaRIII. To our knowledge this is a rare example of an assay that measures platelet phagocytosis in vitro. The results suggest that FcgammaRI plays a major role in anti-HPA-1a-mediated platelet phagocytosis by monocytes while FcgammaRIIa, is of little or minor importance only. Moreover, the findings indicate the use of H22 as an alternative to interavenous Ig (ivIg) in the management of FAIT/NAIT.
Adult↗
[Respiratory sinus arrhythmia and voluntary control of breathing].
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Arrhythmia, Sinus↗
Comparison between the respiratory inductance plethysmography signal derivative and the airflow signal.
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Adult↗
Methods for averaging respiratory flow profiles in humans.
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Humans↗
[Ovarian abscess due to Actinomyces sp. in absence of an intrauterine contraceptive device].
The disease caused by Actinomyces spp. is often of difficult diagnosis. Actinomyces spp. are anaerobic or microaerophilic non-spore-forming gram-positive rods that may reach, occasionally, the normal female genital tract. IUD and pessaries facilitate the access of the microorganisms to the pelvis. We report an unusual case of ovarian infection by Actinomyces sp. in a 41 year-old female without IUD, admitted at the Institute in November 1998, with persistent fever. She had had an early menopause 3 years before, and had received hormonal replacement therapy. Usual and unusual infections were discarded by microbiological and serologic studies. Abdominal ultrasonography showed a slight left pyelocalycial dilatation and a simple cyst in the left ovary; heart ultrasonography was normal. Gynecological examination showed an enlarged uterus, similar to an 8 week pregnancy, painless, and fixed anexial masses. The transvaginal ultrasonography showed uterine myomas, one of them of 42 mm in the isthmus region, large ovaries, cystic, with acoustic shadows, and the left one with a septum. The preoperative diagnosis was infected bilateral cystic teratoma. The procedure was an exploratory laparotomy, followed by a bilateral salpingo-oophorectomy. The specimen studies showed an endometrioma with calcium deposits in the wall of the right ovary, and an abscess in the left ovary, also with calcification of the wall. The sample from the left abscess developed Actinomyces sp. After surgery, and treatment with penicillin, the fever disappeared. It is important to remark that the ovarian infection by Actinomyces sp. can also occur in patients without an IUD or a pessary; it might cause anexial images that can be interpreted as a tumour, inducing to erroneous diagnosis and treatment.
Abscess↗
Postural breathing pattern changes in patients with myotonic dystrophy.
We recorded by pneumotachography the breathing in nine patients with myotonic dystrophy (MD), both seated and supine and with eyes open in both positions. Irregular breathing (coefficient of variation >20% for VT and TTOT) was observed in six of the patients, two of whom showed irregularity in both positions whilst the remaining four had irregular breathing only when supine. In addition, in this latter group, irregularities first appeared in VT and only after a few minutes in TTOT. Whereas in the group exhibiting irregular breathing in both seated and supine positions, irregularities were observed throughout the recording. However, no significant difference in any ventilatory variable was observed as between the two postures. Rib cage (RC) and abdomen (AB) motions were recorded by uncalibrated respiratory inductance plethysmography. Although for MD patients the mean values of the RC/AB ratio lay within the normal range the relative decrease in value as between seated (0.78+/-0.52) and supine (0.31+/-0.13) position was less than in healthy subjects. These observations suggest that MD may cause deficiencies in several mechanisms. Analyses of the respiratory pattern in each patient may provide information leading to the identification of the impaired respiratory mechanisms.
Adult↗
Breathing pattern in humans: diversity and individuality.
In adult awake human subjects at rest, there exists a diversity in the breathing pattern not only in terms of tidal volume and inspiratory and expiratory duration and derived variables (TTOT, VT/TI and TI/TTOT) but also in the airflow profile. Besides this diversity, in every recording of ventilation at rest in steady-state condition breath-to-breath fluctuations are observed in ventilatory variables. This variability is non random and may be explained either by a central neural mechanism or by instability in the chemical feedback loops. Beyond this variability, each individual appears to select one particular pattern among the infinite number of possible combination of ventilatory variables and airflow profile. This one particular pattern appears to be a relatively stable characteristic of an adult individual being reproducible in several conditions and above all, after a long period of time. Consequences of this individuality of breathing pattern are discussed with regard to the selection of control subjects for a study and also per se: are there physiological situations where differences may be observed solely because of the differences in the pattern of breathing?
Humans↗
In vivo measurement of lung capillary-alveolar macromolecule permeability by saturation bronchoalveolar lavage.
OBJECTIVE: Measurement of capillary-alveolar permeability to fluorescein isothiocyanate-dextran (FITC-D) (molecular mass, 71,300 daltons) by a sequential bronchoalveolar lavage (BAL) technique. DESIGN: Animal research. SETTING: The Department of Physiology at a scientific and medical university. SUBJECTS: Nine anesthetized and mechanically ventilated dogs. INTERVENTIONS: Two separate experiments were performed in each subject-an initial control experiment followed by an oleic acid-induced lung injury. The indicator was administered at constant blood concentration before serial BAL including eight fluid instillation-recovery cycles. MEASUREMENTS: Plasma to BAL solute clearance at saturation (capillary-alveolar clearance at saturation, mL/min) was calculated and normalized to lavage fluid volume (measured by 1251 serum albumin dilution) to obtain a transport rate (TR) constant. MAIN RESULTS: TR for FITC-D70 was 4.0+/-0.8 and 46.1+/-18.1 x 10(-5) x min(-1) in control and injured lung, respectively (p < .02). Capillary-alveolar clearance of FITC-D70 was not affected by the lavage procedure itself. TR reflected essentially epithelial permeability in normal lung and combined epithelial and endothelial permeability in injured lung. A significant correlation was found between cardiac output and TR in injured lung. CONCLUSIONS: Saturation BAL allowed us to estimate capillary-alveolar macromolecule permeability in vivo in dogs. Further study may allow bedside evaluation of lung injury by BAL in patients.
Animals↗
Cardiorespiratory interactions during resistive load breathing.
The addition to the respiratory system of a resistive load results in breathing pattern changes and in negative intrathoracic pressure increases. The aim of this study was to use resistive load breathing as a stimulus to the cardiorespiratory interaction and to examine the extent of the changes in heart rate variability (HRV) and respiratory sinus arrhythmia (RSA) in relation to the breathing pattern changes. HRV and RSA were studied in seven healthy subjects where four resistive loads were applied in a random order during the breath and 8-min recording made in each condition. The HRV spectral power components were computed from the R-R interval sequences, and the RSA amplitude and phase were computed from the sinusoid fitting the instantaneous heart rate within each breath. Adding resistive loads resulted in 1) increasing respiratory period, 2) unchanging heart rate, and 3) increasing HRV and changing RSA characteristics. HRV and RSA characteristics are linearly correlated to the respiratory period. These modifications appear to be linked to load-induced changes in the respiratory period in each individual, because HRV and RSA characteristics are similar at a respiratory period obtained either by loading or by imposed frequency breathing. The present results are discussed with regard to the importance of the breathing cycle duration in these cardiorespiratory interactions, suggesting that these interactions may depend on the time necessary for activation and dissipation of neurotransmitters involved in RSA.
Adult↗
Breathing pattern in patients with Parkinson's disease.
The improvement in motor performance resulting from levodopa administration in patients with Parkinson's disease (PD) provides the opportunity to investigate ventilatory changes brought about by the disease. The aim of this study has been to investigate these changes in order to specify the mechanisms of the impairment in breathing in PD. Breathing patterns at rest were investigated in 11 patients with idiopathic PD both before (OFF) and after (ON) administration of levodopa at a dose improving their motor performance by at least 30%. Airflow (Fleisch head mounted on a mask), rib cage and abdomen movements (inductance plethysmography) were recorded in the OFF condition 1 h after subjects woke up. Subjects then received levodopa and a new set of recordings was obtained 1 h later, in the ON condition. Breath-by-breath processing of recordings was carried out, and tidal volume (VT), inspiratory (TI) and expiratory (TE) durations were measured. The main finding was a lengthening of TI resulting in a decrease in ventilation and in VT/TI, and an increase in TI/TTOT in the ON compared to the OFF condition. In the ON condition abnormal rib cage-abdomen plots patterns were found in four out of six subjects. A hypothesis on the effect of PD on breathing is proposed on grounds of normal diaphragmatic activity but impaired activity of the other respiratory muscles and more specifically the intercostal muscles.
Aged↗
New statistical method for detection and quantification of respiratory sinus arrhythmia.
A statistical method with the advantages of 1) enabling graphical representation of within-respiratory cycle heart rate variations, 2) detecting the presence of respiratory sinus arrhythmia (RSA) in a moving window, and 3) providing breath-by-breath RSA amplitude and phase obtained from the fitting of a sinusoid to the instantaneous relative heart rate is presented.
Adolescent↗
Effects of resistive loading on the pattern of breathing.
In order to determine changes in breathing patterns brought about by resistive loading, ventilation was recorded in 11 healthy subjects with four linear resistances (3.57, 5.75, 8.76 and 13.13 cmH2O L(-1) sec) added in a random order throughout the entire breath. At steady state, a breath-by-breath analysis of airflow was used to quantify the pattern of breathing in terms of respiratory variables: TI, TE, Tt, VT, VT/TI, TI/Tt, and by taking TI, TE, VT all together (TRIAD) and also the shape of the entire airflow profile quantified by harmonic analysis (ASTER). Group analysis using ANOVA showed significant changes in all variables. There were increasing changes with increasing loads in all variables, the smallest changes being in TI/Tt. Within to between-individual comparisons between two loads showed that only TI/Tt and the ASTER were more similar within than between-individuals for all comparisons. It was concluded that at steady state mechanisms of load compensation come into play inducing changes in the pattern of breathing proportional to the loads while maintaining some of the individual characteristics.
Adaptation, Physiological↗
Blood flow vs. venous pressure effects on filtration coefficient in oleic acid-injured lung.
On the basis of changes in capillary filtration coefficient (Kfc) in 24 rabbit lungs, we determined whether elevations in pulmonary venous pressure (Ppv) or blood flow (BF) produced differences in filtration surface area in oleic acid-injured (OA) or control (Con) lungs. Lungs were cyclically ventilated and perfused under zone 3 conditions by using blood and 5% albumin with no pharmacological modulation of vascular tone. Pulmonary arterial, venous, and capillary pressures were measured by using arterial, venous, and double occlusion. Before and during each Kfc-measurement maneuver, microvascular/total vascular compliance was measured by using venous occlusion. Kfc was measured before and 30 min after injury, by using a Ppv elevation of 7 cmH2O or a BF elevation from 1 to 2 l . min-1 . 100 g-1 to obtain a similar double occlusion pressure. Pulmonary arterial pressure increased more with BF than with Ppv in both Con and OA lungs [29 +/- 2 vs. 19 +/- 0.7 (means +/- SE) cmH2O; P < 0. 001]. In OA lungs compared with Con lungs, values of Kfc (200 +/- 40 vs. 83 +/- 14%, respectively; P < 0.01) and microvascular/total vascular compliance ratio (86 +/- 4 vs. 68 +/- 5%, respectively; P < 0.01) increased more with BF than with Ppv. In conclusion, for a given OA-induced increase in hydraulic conductivity, BF elevation increased filtration surface area more than did Ppv elevation. The steep pulmonary pressure profile induced by increased BF could result in the recruitment of injured capillaries and could also shift downstream the compression point of blind (zone 1) and open injured vessels (zone 2).
Animals↗
In vivo quantitation of epithelial lining fluid in dog lung.
We used an original saturation bronchoalveolar lavage (SBAL) technique (Eur. Respir. J. 1995;8[Suppl. 19]398S) to quantitate lung epithelial lining fluid volume (VELF) in dogs in two separate experiments: control and after oleic-acid-induced injury. We confirmed the hypothesis that 99mTc-DTPA, infused at constant plasma activity, reaches equilibrium with epithelial lining fluid after 90 min. We performed eight sequential lavages 215 min after beginning the infusion of 99mTc-DTPA. 99mTc-DTPA activity (Qn) in the lavage fluid increased linearly with time, suggesting transport from the plasma into the alveoli during lavage. We extrapolated Qn to time zero (Q0), when 99mTc-DTPA was not affected by lavage. VELF was calculated from: VELF = Q0/Cp, (Cp: 99mTc-DTPA mean plasma activity). 125I-albumin was used as a nondiffusible alveolar indicator to measure the fluid volume present in the lavaged segment (Vt,n). Vt,n plateaud for n >= 4. VELF/Vt,n(n = 5,8) was 1.7 +/- 0.4 and 25.0 +/- 4.4% (p < 0.05) in control and injury experiments, respectively. SBAL allowed reliable measurements of VELF and detection of alveolar edema fluid in the injured lung.
Albumins↗
Chlorine gas induced acute lung injury in isolated rabbit lung.
This study was designed to investigate the pathogenesis of chlorine gas (Cl2) induced acute lung injury and oedema. Isolated blood-perfused rabbit lungs were ventilated either with air (n=7) or air plus 500 parts per million (ppm) of Cl2 (n=7) for 10 min. Capillary pressure, measured by analysing the pressure/time transients of pulmonary arterial, venous and double (both arterial and venous) occlusions, was unchanged in both groups. In Cl2-exposed lungs, the fluid filtration rate increased from -0.228+/-0.25 to 1.823+/-1.23 mL min(-1) x 100 g(-1) (p<0.001) and the filtration coefficient increased from 0.091+/-0.01 to 0.259+/-0.07 mL x min(-1) x cmH2O(-1) x 100 g(-1) (p<0.001). No changes were observed in the control lungs. The extravascular lung water/blood-free dry weight ratio was 8.6+/-1.6 in the Cl2 group and 4.0+/-0.5 in the control group (p<0.001), confirming that the increase in lung weight was related to accumulation of extravascular fluid. Although the alveolar flooding by oedema is explained, in part, by the Cl2-induced epithelial injury, our results suggest that Cl2 exposure induces acute lung injury and oedema due to an increased microvascular permeability.
Animals↗
Evaluation of respiratory inductive plethysmography: accuracy for analysis of respiratory waveforms.
OBJECTIVE: To assess the accuracy of respiratory inductive plethysmography (RIP) waveforms to those obtained with whole body plethysmograph (BP) as this device gives a plethysmographic signal and a pneumotachograph (PNT). DESIGN: Randomized controlled trial. SETTING: Physiologic laboratory in a university hospital. PARTICIPANTS: Eleven subjects from the laboratory staff. INTERVENTIONS: This study was achieved during four consecutive periods in subjects breathing spontaneously and through different added resistive loads. Using the least square method calibration, two RIP waveforms, VRIP.BP(t) and VRIP.PNT(t), were simultaneously calculated with coefficients obtained from BP and from PNT volume waveforms, respectively VBP(t) and VPNT(t). For each recording, to compare volume waveforms, we calculated their differences in term of distances, DRIP-BP and DRIP-PNT, between the normalized RIP volume signal (respectively, VRIP.BP[t] and VRIP.PNT[t]) and its normalized reference (respectively, VBP[t] and VPNT[t]). We also calculated the distance DPNT-BP between the two normalized references VBP(t) and VPNT(t). RESULTS: No significant effect of load or time on the distance occurred. Including all the recordings, the mean distance DRIP-BP (3.4+/-1.1%) appears significantly lower than both the mean distance DRIP-PNT (4.5+/-1.3%; p<0.04) and the mean distance DPNT-BP (4.6+/-0.9%; p<0.008). For each period or load level, DRIP-BP appears to be lower than DRIP-PNT and DPNT-BP. CONCLUSION: The RIP seems reasonably accurate for analysis of respiratory waveform while subjects subsequently breathe against resistive loads.
Adult↗
The effects of breathing pattern training on ventilatory function in patients with COPD.
The purpose of this study was to assess the effects of a particular breathing pattern training (BPT) on forced expiratory volume during the first second (FEV1) and forced vital capacity (FVC) in patients with chronic obstructive pulmonary disease (COPD). The subjects adjusted each breath to a target breath displayed on a video screen, by using visual feedback. This target was chosen in an individual sample recorded at rest. We used a randomized, controlled group design. Twenty patients with stable COPD, FEV1 less than 1.5 liters, undergoing a traditional rehabilitation program were randomly assigned to the BPT group or to the control group. Each BPT subject underwent 30-35 training sessions spread out over four weeks, in addition to the traditional program. FEV1 and FVC were performed before and after this program. ANOVAs showed that FEV1 and FVC significantly improved in BPT subjects, with a mean percent increase of 22% and 19%, respectively. Corresponding changes in controls were not significant. This study showed short-term increases in FEV1 and FVC in COPD patients practicing BPT in addition to respiratory rehabilitation, in comparison with controls. Further studies should incorporate outcome data to clarify the mechanisms and the duration of this effect.
Aged↗