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M Orozco-Levi

Publications and source records attributed to M Orozco-Levi.

35 records · Page 2Linked to original sources
PubMed2000

[Mechanical and metabolic reproducibility of resistance test of expiratory muscles with incremental threshold loading].

BACKGROUND: The study of respiratory muscle endurance has mainly focused on inspiratory muscles. A new method to measure expiratory muscle endurance, through incremental threshold loading using a weighted plunger valve, has recently been described. OBJECTIVES: To evaluate the mechanical features of the plunger valve and the reproducibility of the method from the standpoint of both mechanics and metabolism. METHODS: Four untrained healthy subjects performed an incremental test with expiratory threshold loading (50 g every 2 min) on each of three non-consecutive days; each test continued until the subject could no longer open the valve. Mouth pressure was recorded continuously during each test; on the first two test days, oxygen consumption (VO2) was also measured. RESULTS: Opening and closing pressures were the same and were independent of expiratory flow, with a linear load-pressure relationship (4 cmH2O) for every 10 g of weight). The maximal tolerated load (MTL) in the three tests was stable for two of the subjects, whereas the maximal load was reached by the other two subjects in the second and third tests, respectively. When MTL was reached in the third test, mean and peak mouth pressures (the latter expressed as percent of maximal expiratory pressure [MEP]) were 49 +/- 4% and 71 +/- 4%, respectively; the expiratory tension-time index measured at the mouth ([PMEANmouth/MEP] x [TE/Ttot]) was 0.25 +/- 0.02 (TE: expiratory time; Ttot: total time). In the first and second tests, we also measured oxygen consumption of the recruited muscles, which were mainly the expiratory muscles (VO2respmax); consumption in the last test was 213 +/- 65 ml O2/min (2.9 +/- 1.1 ml O2/kg/min). The intraindividual coefficient of variation ranged from 6.3% to 19.5% for the mechanical parameters and from 14% to 21% for the metabolic ones. CONCLUSIONS: The expiratory endurance test using a threshold valve allows quantification of muscle and metabolic reserve under incremental expiratory loads. The valve has appropriate mechanical characteristics for this purpose and reproducibility is acceptable, through the precise determination of the may require up to three tests.

Adult↗
PubMed2000

[The characteristics of the mechanical activity of the respiratory muscles during the diaphragmatic respiration technic].

UNLABELLED: Noteworthy among breathing training techniques is so-called diaphragmatic breathing. In spite of the technique's name, however, little is known of the functional characteristics of this ventilatory method. OBJECTIVE: To asses the mechanics of respiratory muscles, particularly diaphragm muscles, during diaphragmatic breathing in patients with severe chronic obstructive pulmonary disease (COPD). METHODS: Ventilatory pattern and respiratory pressures (abdominal [Pga], intrathoracic [Pes] and transdiaphragmatic [Pdi]) were studied in 10 patients with severe COPD in stable phase (age 69 +/- 6 years, FEV1 33 +/- 12% ref) at baseline and during deep breathing with spontaneous muscle recruitment (SMR) and during breathing training. Measurements were taken with the patient seated and in supine decubitus position. RESULTS: In seated position ventilatory pattern was similar with SMR and during breathing training. Mean Pdi during airflow, however, was greater during breathing training than with SMR (34.8 +/- 8.0 and 29.3 +/- 9.3 cmH2O, respectively, p < 0.05) for similar levels of Pes. Mechanical effectiveness of the diaphragm expressed as Vt/Pdi) was less during breathing training, however (36.1 +/- 10.4 and 49.5 +/- 15.8 cc/cmH2O, p < 0.05), with no changes in overall efficacy of respiratory muscles (Vt/Pes). In supine decubitus position, ventilatory patterns of SMR and breathing training were similar, although Vt and T1 were slightly higher in the latter (1,065 +/- 305 vs. 1,211 +/- 314 cc, p < 0.01; and 2.76 +/- 1.32 vs. 3.07 +/- 1.23 sec, p < 0.05). Pdi was also higher during breathing training (29.7 +/- 10.2 and 38.0 +/- 10.5 cmH2O, p < 0.05), although accompanied in this case by a higher Pes (21.2 +/- 7.5 to 26.4 +/- 8.4 cmH2O, p < 0.005). In supine decubitus position, the effectiveness of both diaphragm muscles and respiratory muscles overall was similar for both ventilatory modes. CONCLUSIONS: Breathing training truly involves greater use of the diaphragm, both in seated and supine decubitus positions. Breathing training does not provide greater ventilatory efficacy than SMR, however, in COPD patients.

Aged↗
PubMed2000

[Obtaining samples of the human diaphragm during upper laparotomy. A structural analysis].

UNLABELLED: The diaphragm seems to undergo adaptive structural change in chronic obstructive pulmonary disease. The possibility of obtaining muscle specimens is limited, however, particularly when respiratory function is severely affected. OBJECTIVE: To assess the viability of a new technique for obtaining diaphragm muscle samples appropriate for structural assessment even from patients with severe functional change, and to study the size of fibers in relation to severity of disease. METHODS: Fifteen muscle specimens were obtained from patients (aged 57 +/- 15 years) by abdominal laparotomy. All had undergone full lung function testing. Muscle samples were taken during surgery using a new technique involving formation of a tobacco pouch with dome biopsy. The method had been previously validated in animal models. Later, the biopsies were processed to evaluate fiber proportions and sizes (ATPase dyes at different levels of pH). RESULTS: The 15 patients had a wide range of lung function results (FEV1 22-120% ref); 4 were severely affected (FEV1 < or = 50% ref). Nutritional status was normal in all cases; FEV1/FVC was 67 +/- 13%, RV was 134 +/- 55% ref, maximal mouth pressure (PImmax) was -75 +/- 27 cmH2O, transdiaphragmatic pressure (PIdimax) was 96 +/- 26 cmH2O, DLCO was 87 +/- 26% ref and PaO2 was 89 +/- 14 mmHg. We were able to obtain specimens valid for structural analysis from all patients with no complications. Light type I fibers predominated (54 +/- 9%) and size was normal overall (57 +/- 9 microns minimum diameter [Dm] atrophy index 195 +/- 243, and hypertrophy index 66 +/- 78), with no differences between the two fiber subtypes (Dm 58 +/- 8 microns for type I and 61 +/- 8 microns for type II). Overall size correlated inversely with static volumes (e.g. Dm with RV, r = -0.729, p < 0.01). CONCLUSIONS: The laparoscopic technique described is simple and safe for use in humans to obtain diaphragm muscle specimens that are valid for morphometric analysis, allowing us to enlarge the range of subjects that can be enrolled for this type of study. The fiber muscles studied are smaller when functional involvement is greater in chronic obstructive pulmonary disease.

Adult↗
PubMed1999

[Respiratory muscle force and resistance in patients with SAHS. The effect of using nighttime CPAP].

UNLABELLED: During nighttime episodes of obstructive apnea in patients with sleep apnea-hypopnea syndrome (SAHS), repeated and progressive inspiratory efforts are made. Such intense nighttime activity can have a deleterious effect on daytime function of respiratory muscles. OBJECTIVE: The objective of this study was to evaluate daytime respiratory muscle function in a group of SAHS patients before and after two months of treatment with nighttime continuous positive airway pressure (CPAP). METHODS: We enrolled 12 patients with SAHS and 10 normal subjects (control group). To evaluate respiratory muscle strength we measured maximum esophageal pressure (Pesmax), transdiaphragmatic pressure (Pdimax) and inspiratory pressure in the mouth (PM). Respiratory muscle resistance was assessed using peak pressure in the mouth (PMPeak), time of tolerance (Tlim) and maximum inspiratory pressure-time index (PTimax). We also analyzed the nighttime function of respiratory muscles during apneic episodes in 10 of the 12 SAHS patients. We propose and define an index of nighttime respiratory muscle activity (RMian) as the product of the tension-time index for the diaphragm observed at the end of nighttime apneic episodes (TTdiapnea) and the apnea-hypopnea index (AHI). RESULTS: Respiratory muscle strength was similar in the two groups and no changes were observed in SAHS patients after treatment with nighttime CPAP. However, tolerance was lower in SAHS patients (PMpeak--30%, Tlim--31% and PTimax--49%). Two months of nighttime CPAP normalized all three variables in these patients. MRian was related to percent improvement in PMpeak after treatment with nighttime CPAP in SAHS patients (r = 0.66, p < 0.04). CONCLUSION: SAHS has an adverse effect on the daytime endurance of respiratory muscles that is proportional to the increase of nighttime mechanical muscle activity. The application of nighttime CPAP is restorative, probably because it allows respiratory muscles to rest.

Adult↗
PubMed1999

[Diaphragmatic function during exercise in patients with severe COPD].

UNLABELLED: Ventilatory requirements increase during exercise. The respiratory muscles of patients with chronic obstructive pulmonary disease (COPD) are at a particular disadvantage when dealing with such increased demand. The objective of this study was to evaluate the changes in respiratory muscles brought on by exercise in such patients. METHODS: Twelve patients with severe CFOPD (FEV1 < 50% ref., 63 +/- 7 years) were enrolled. Breathing patterns and esophageal (Pes and transdiaphragmatic (Pdi) pressures and SaO2 were measured during submaximal exercise/Ecsbmax, 60% of the maximum tolerated load). A sniff maneuver was performed with the patients breathing ambient air with added oxygen to achieve 99% SaO2. We also measured level of FRC by inductive plethysmograph in a subgroup of five patients. RESULTS: During EXsbmáx, SaO2 decreased (from 95.0 +/- 2.1 to 92.3 +/- 4.0%; p < 0.01); Vt increased (717 +/- 199 to 990 +/- 297 cc, p < 0.01), as did respiratory rate (RR, 17 +/- 6 a 28 +/- 9; p < 0.01). Pes and Pdi were greater at Vt, changing from -12.4 +/- 4.8 to -27.0 +/- 10.1 and 16.6 +/- 6.1 to 30.4 +/- 12.4 cmH2O, respectively (p < 0.01 in both cases), whereas no significant changes were observed for maximal effort (Pesmax, -61.4 +/- 16.5 cersus -65.9 +/- 15.2 cmH2O; Pdimac 89.7 +/- 26.1 versus 81.7 +/- 35.7 cmH2O). Used as a global measure, Pdi/Pdimáx worsened (0.21 +/- 0.12 a 0.42 +/- 0.20; p < 0.01), as dud the diaphragm tension-time (TTdi; 0.07 +/- 0.04 to 0.15 +/- 0.06, p < 0.01). Intrinsic positive end-expiratory pressure (PEEPi) increased an estimated 2.7 +/- 2.1 to 9.4 +/- 5.8 cmH2O (p < 0.001), while FRC (delta 357 +/- 274 ml). Durante el EXsbmáx with oxygen supplementation, SaO2 did not decrease. However supplementation, though Ti/TTOT and maximal pressures remained unchanged. CONCLUSIONS: Respiratory muscle function changes induced by Exsbmáx seem to relate mainly to a worsening of system mechanics.

Data Interpretation, Statistical↗
PubMed1999

Subcellular adaptation of the human diaphragm in chronic obstructive pulmonary disease.

Pulmonary hyperinflation impairs the function of the diaphragm in patients with chronic obstructive pulmonary disease (COPD). However, it has been recently demonstrated that the muscle can counterbalance this deleterious effect, remodelling its structure (i.e. changing the proportion of different types of fibres). The aim of this study was to investigate whether the functional impairment present in COPD patients can be associated with structural subcellular changes of the diaphragm. Twenty individuals (60+/-9 yrs, 11 COPD patients and 9 subjects with normal spirometry) undergoing thoracotomy were included. Nutritional status and respiratory function were evaluated prior to surgery. Then, small samples of the costal diaphragm were obtained and processed for electron microscopy analysis. COPD patients showed a mean forced expiratory volume in one second (FEV1) of 60+/-9% predicted, a higher concentration of mitochondria (n(mit)) in their diaphragm than controls (0.62+/-0.16 versus 0.46+/-0.16 mitochondrial transections (mt) x microm(-2), p<0.05). On the other hand, subjects with air trapping (residual volume (RV)/total lung capacity (TLC) >37%) disclosed not only a higher n(mit) (0.63+/-0.17 versus 0.43+/-0.07 mt x microm(-2), p<0.05) but shorter sarcomeres (L(sar)) than subjects without this functional abnormality (2.08+/-0.16 to 2.27+/-0.15 microm, p<0.05). Glycogen stores were similar in COPD and controls. The severity of airways obstruction (i.e. FEV1) was associated with n(mit) (r=-0.555, p=0.01), while the amount of air trapping (i.e. RV/TLC) was found to correlate with both n(mit) (r=0.631, p=0.005) and L(sar) (r=-0.526, p<0.05). Finally, maximal inspiratory pressure (PI,max) inversely correlated with n(mit) (r=-0.547, p=0.01). In conclusion, impairment in lung function occurring in patients with chronic obstructive pulmonary disease is associated with subcellular changes in their diaphragm, namely a shortening in the length of sarcomeres and an increase in the concentration of mitochondria. These changes form a part of muscle remodelling, probably contributing to a better functional muscle behaviour.

Adaptation, Physiological↗
PubMed1998

Structure and function relationships of the respiratory muscles.

Potential relationships between the structure of the diaphragm and external intercostals and several indices of respiratory muscle function, lung function and nutrition in 27 patients (61+/-10 yrs of age) subjected to thoracotomy as a result of a lung neoplasm have been investigated. Prior to surgery the nutritional status of the patients was assessed and lung function (spirometry, lung volumes, transfer factor of the lungs for carbon monoxide, arterial blood gases) and respiratory muscle function (maximal inspiratory pressure (MIP) and diaphragmatic function were measured). Biopsies of the diaphragm (and external intercostals) were obtained during surgery. On average, patients showed mild airflow limitation (forced expiratory volume in one second (FEV1), 70+/-14% of predicted value, FEV1/forced vital capacity (FVC), 70+/-9%) with some air trapping (residual volume (RV), 139+/-50% pred) and normal gas exchange (arterial oxygen tension (Pa,O2), 11.3+/-1.33 kPa (85+/-10 mmHg)) and arterial carbon dioxide tension (Pa,CO2) 5.4+/-0.5 kPa (40.6+/-4 mmHg). MIP was 77+/-25% pred; maximal transdiaphragmatic pressure was 90+/-27 cmH2O. Most morphometric measurements of the diaphragm and external intercostals were within the range of values reported previously in other skeletal muscles. The size of the fibres of these two respiratory muscles was positively related (p<0.05) to MIP (% pred). There were no significant relationships between the structure of both muscles and nutritional status or any index of lung function. In conclusion, in the population studied, the fibre size of the diaphragm and external intercostals appears to relate to their ability to generate force.

Diaphragm↗
PubMed1997

[The diaphragm].

Explore the source record for details and available documents.

Diaphragm↗
PubMed1995

[Muscle relaxants in the morphometric study of the respiratory muscles in human beings].

The morphological examination of respiratory muscle can be affected by muscular contraction following biopsy. Most morphometric studies of respiratory muscles, however, have been carried out without taking into account this factor, the effect of which can be reduced by using relaxants when taking samples. Objective. To examine the effect of using a relaxant in the morphometric analysis of muscle fibers. We examined 31 muscle samples from 7 patients. Immediately after removal, each pipe was divided in half. One was placed in an isotonic physiological solution and the other in a solution of curare 0.02%. Later, both samples were processed for morphometric study with ATP-ase, NADTH and PAS tincture. Morphological data recorded for the different types of fibers included measurement of minimum diameter (Dmin), atrophy and hypertrophy indices (AI and HI) and heterogeneity of distribution (SDDmin). The Dmin was smaller in fibers transported in a curare solution than in those transported in physiological solution (67 +/- 2 microns vs. 71 +/- microns, p < 0.05). The same was true of SDDmin (13 +/- 3 vs. 12 +/- 3, p < 0.05), HI (300 +/- 88 vs. 457 +/- 107, p < 0.05). Likewise, we found a similar direct correlation between size of fibers processed with physiological solution and those processed in curare (Dmin, r = 0.731, p < 0.001; HI, r = 0.827, p < 0.001; SDDmin, r = 0.636, p < 0.0001). The use of relaxants in processing muscle samples prevents contraction and should be used systematically in the morphological analysis of muscle fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1995

Structure of the latissimus dorsi muscle and respiratory function.

The aim of this study was to evaluate whether respiratory function influences the structure of the latissimus dorsi muscle (LD). Twelve patients (58 +/- 10 yr) undergoing thoracotomy were studied. Lung and respiratory muscle function were evaluated before surgery. Patients showed a forced expired volume in 1 s (FEV1) of 67 +/- 16% of the reference value, an FEV1-forced vital capacity ratio of 69 +/- 9%, a maximal inspiratory pressure of 101 +/- 21% of the reference value, and a tension-time index of the diaphragm (TTdi) of 0.04 +/- 0.02. When patients were exposed to 8% CO2 breathing, TTdi increased to 0.06 +/- 0.03 (P < 0.05). The structural analysis of LD showed that 51 +/- 5% of the fibers were type I. The diameter was 56 +/- 9 microns for type I fibers and 61 +/- 9 microns for type II fibers, whereas the hypertrophy factor was 87 +/- 94 and 172 +/- 208 for type I and II fibers, respectively. Interestingly, the histogram distribution of the LD fibers was unimodal in two of the three individuals with normal lung function and bimodal (additional mode of hypertrophic fibers) in seven of the nine patients with chronic obstructive pulmonary disease. An inverse relationship was found between the %FEV1-forced vital capacity ratio and both the diameter of the fibers (type I: r = -0.773, P < 0.005; type II: r = -0.590, P < 0.05) and the hypertrophy factors (type I: r = -0.647, P < 0.05; type II: r = -0.575, P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Semirecumbent position protects from pulmonary aspiration but not completely from gastroesophageal reflux in mechanically ventilated patients.

The aim of this study was to evaluate the effect of two body positions (supine and semirecumbency) on the dynamics of gastroesophageal reflux (GER) in 15 patients requiring mechanical ventilation and having a nasogastric tube in place. Samples of gastric contents, pharyngeal and bronchial secretions, and blood were obtained at baseline and every hour during a period of 5 h after nasogastric tube isotopic instillation of 37 megabecquerels of Tc99m. Radioactivity counting (RAc) was performed using a gamma counter with correction for decay. Irrespective of the body position, all patients showed at 3, 4, and 5 h after the isotope instillation a significant increase in RAc of the oropharyngeal contents (p < 0.05, each), indicating GER. Although RAc values in the pharynx were higher in supine from 1 through 4 h (p < 0.05), at the end of the study (5 h) the values did not differ between each position. Likewise, the slopes of the regression lines of sequential oropharyngeal RAc values were not different between each position (0.39 +/- 0.09 versus 0.45 +/- 0.11, respectively). In contrast, RAc values in bronchial secretions were higher at 5 h in the supine position compared with baseline (p < 0.05) and to semirecumbency (p < 0.01). These results strongly support that GER in mechanically ventilated patients with a nasogastric tube is a feature occurring irrespective of body position. Semirecumbent position does not protect completely from GER and subsequently from oropharyngeal colonization from gastric origin.

Cross Infection↗
PubMed1995

Activity of latissimus dorsi muscle during inspiratory threshold loads.

The ability of the latissimus dorsi muscle (LD) to participate as an accessory inspiratory muscle has been the subject of controversy. Electromyographic (EGM) activity of LD was evaluated in 11 healthy subjects (aged 30 +/- 2 yrs; forced expiratory volume in one second (FEV1) 106 +/- 5% predicted; maximal inspiratory pressure (Pmax), 120 +/- 6 cmH2O) under different breathing conditions. The ipsilateral biceps brachii was chosen as the control muscle. The EMG was recorded from surface electrodes, but needle electrodes were also used for LD evaluation in a subset of three subjects. The EMG signal from both muscles was recorded simultaneously, rectified and integrated, with subtraction of the electrocardiographic signal. Situations evaluated were: 1) maximal voluntary contraction (MVC); 2) apnoea; and 3) breathing under progressive inspiratory threshold loads (20-100% Pmax, at 20% intervals). A close relationship was evident between LD recordings from surface and needle electrodes (r = 0.975). Activity of LD at baseline was 1.8 +/- 0.4% MVC, and showed a phasic increase during inspiration under loads. This change had a linear tendency and was significant for loads corresponding to 40, 60, 80 and 100% of Pmax when compared to the control muscle. At this latter level, LD activity was equivalent to 32 +/- 5% MVC (range 11-61%), whereas mean activity of the control muscle was less than 7.5% MVC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Usefulness of respiratory endoscopy in patients with severe rhonchi and/or sleep apnea syndrome].

BACKGROUND: Obstruction of the upper respiratory tract is the most common cause of the sleep apnea syndrome (SAS). Different methods have been used to localize this obstruction and give the appropriate treatment. The aim of this study was to evaluate the usefulness of respiratory endoscopy performed during arousal to identify the site and cause of the obstruction in patients with severe rhoncopathy and/or SAS. METHODS: Sixty-eight patients with acute rhoncopathy were included in the study with 36 also fulfilling polysomnographic criteria of SAS (36%). The endoscopy was performed via the upper respiratory tract with inspiratory collapse at each level being evaluated in both easy respiration and during the Müller manoeuver. RESULTS: The site and cause of the obstruction was identified in 61 patients (90%, CI 95%, 79.9 +/- 95.8). In most cases the Müller manoeuver best demonstrated the collapse. The predominant obstruction was in the nasopharyngeal region (72%, mainly associated to changes in soft palate), followed by obstruction in the oropharyngeal region at the base of the tongue (29%). Multiple localization of the obstruction was observed in 19 patients. CONCLUSIONS: Endoscopy performed during arousal may allow the identification of the site and cause of obstruction in most of the patients with rhoncopathy and sleep apnea syndrome, thus aiding in the selecting the most adequate treatment for the patient.

Endoscopy↗
PubMed1994

Simplified exercise test for the initial differential diagnosis of Pneumocystis carinii pneumonia in HIV antibody positive patients.

BACKGROUND: This study was designed to evaluate the usefulness of a simplified exercise test in the differential diagnosis of Pneumocystis carinii pneumonia (PCP). METHODS: Forty five subjects with antibodies against the human immunodeficiency virus (HIV) and pneumonia were included and divided into two groups: those with PCP and those with "other pneumonias" (non-PCP). The test involved pedalling for two minutes on a stretcher bed and was considered positive if SaO2 decreased by at least 3%. RESULTS: During the exercise the mean(SE) SaO2 fell in patients with PCP from 88(4)% to 84(3)%, p < 0.01, whilst it improved slightly in subjects with non-PCP from 91(1)% to 93(3)%, p < 0.05. Sensitivity was 77% and specificity 91%. CONCLUSIONS: This simple test seems potentially useful for the initial investigation of HIV antibody positive patients with pneumonia.

Adult↗