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R Rodríguez-Roisin

Publications and source records attributed to R Rodríguez-Roisin.

17 recordsLinked to original sources
PubMed1996

Effects of erythropoietin on muscle O2 transport during exercise in patients with chronic renal failure.

Erythropoietin (rHuEPO) has proven to be effective in the treatment of anemia of chronic renal failure (CRF). Despite improving the quality of life, peak oxygen uptake after rHuEPO therapy is not improved as much as the increase in hemoglobin concentration ([Hb)] would predict. We hypothesized that this discrepancy is due to failure of O2 transport rates to rise in a manner proportional to [Hb]. To test this, eight patients with CRF undergoing regular hemodialysis were studied pre- and post-rHuEPO ([Hb] = 7.5 +/- 1.0 vs. 12.5 +/- 1.0 g x dl-1) using a standard incremental cycle exercise protocol. A group of 12 healthy sedentary subjects of similar age and anthropometric characteristics served as controls. Arterial and femoral venous blood gas data were obtained and coupled with simultaneous measurements of femoral venous blood flow (Qleg) by thermodilution to obtain O2 delivery and oxygen uptake (VO2). Despite a 68% increase in [Hb], peak VO2 increased by only 33%. This could be explained largely by reduced peak leg blood flow, limiting the gain in O2 delivery to 37%. At peak VO2, after rHuEPO, O2 supply limitation of maximal VO2 was found to occur, permitting the calculation of a value for muscle O2 conductance from capillary to mitochondria (DO2). While DO2 was slightly improved after rHuEPO, it was only 67% of that of sedentary control subjects. This kept maximal oxygen extraction at only 70%. Two important conclusions can be reached from this study. First, the increase in [Hb] produced by rHuEPO is accompanied by a significant reduction in peak blood flow to exercising muscle, which limits the gain in oxygen transport. Second, even after restoration of [Hb], O2 conductance from the muscle capillary to the mitochondria remains considerably below normal.

Adult↗
PubMed1996

Cellular bioenergetics after erythropoietin therapy in chronic renal failure.

After erythropoietin (rHuEPO) therapy, patients with chronic renal failure (CRF) do not improve peak O2 uptake (VO2 peak) as much as expected from the rise in hemoglobin concentration ([Hb]). In a companion study, we explain this phenomenon by the concurrent effects of fall in muscle blood flow after rHuEPO and abnormal capillary O2 conductance observed in CRF patients. The latter is likely associated with a poor muscle microcirculatory network and capillary-myofiber dissociation due to uremic myopathy. Herein, cellular bioenergetics and its relationships with muscle O2 transport, before and after rHuEPO therapy, were examined in eight CRF patients (27 +/- 7.3 [SD] yr) studied pre- and post-rHuEPO ([Hb] = 7.8 +/- 0.7 vs. 11.7 +/- 0.7 g x dl-1) during an incremental cycling exercise protocol. Eight healthy sedentary subjects (26 +/- 3.1 yr) served as controls. We hypothesize that uremic myopathy provokes a cytosolic dysfunction but mitochondrial oxidative capacity is not abnormal. 31P-nuclear magnetic resonance spectra (31P-MRS) from the vastus medialis were obtained throughout the exercise protocol consisting of periods of 2 min exercise (at 1.67 Hz) at increasing work-loads interspersed by resting periods of 2.5 min. On a different day, after an identical exercise protocol, arterial and femoral venous blood gas data were obtained together with simultaneous measurements of femoral venous blood flow (Qleg) to calculate O2 delivery (QO2leg) and O2 uptake (VO2leg). Baseline resting [phosphocreatine] to [inorganic phosphate] ratio ([PCr]/[Pi]) did not change after rHuEPO (8.9 +/- 1.2 vs. 8.8 +/- 1.2, respectively), but it was significantly lower than in controls (10.9 +/- 1.5) (P = 0.01 each). At a given submaximal or peak VO2leg, no effects of rHuEPO were seen on cellular bioenergetics ([PCr]/[Pi] ratio, %[PCr] consumption halftime of [PCr] recovery after exercise), nor in intracellular pH (pHi). The post-rHuEPO bioenergetic status and pHi, at a given VO2leg, were below those observed in the control group. However, at a given pHi, no differences in 31P-MRS data were detected between post-rHuEPO and controls. After rHuEPO, at peak VO2, Qleg fell 20% (P < 0.04), limiting the change in QO2leg to 17%, a value that did not reach statistical significance. The corresponding O2 extraction ratio decreased from 73 +/- 4% to 68 +/- 8.2% (P < 0.03). These changes indicate that maximal O2 flow from microcirculation to mitochondria did not increase despite the 50% increase in [Hb] and explain how peak VO2leg and cellular bioenergetics (31P-MRS) did not change after rHuEPO. Differences in pHi, possibly due to lactate differences, between post-rHeEPO and controls appear to be a key factor in the abnormal muscle cell bioenergetics during exercise observed in CRF patients.

Adult↗
PubMed1995

Relationship between serum IgE and airway responsiveness in adults with asthma.

BACKGROUND: General population studies have shown a relationship between total serum IgE levels and airway responsiveness, but this association has not been documented in patients with asthma. OBJECTIVE: The study assesses the cross-sectional relationship between IgE levels and airway responsiveness in 208 subjects who had had emergency department treatment for asthma at least 2 years earlier. METHODS: All participants completed a standardized respiratory questionnaire and underwent spirometry, allergy skin testing, and a dose-response methacholine challenge test. RESULTS: After adjusting for age and gender, the percentage of patients with asthma and airway responsiveness (provocative concentration causing a 20% fall in forced expiratory volume in 1 second [PC20] < or = 8 mg/ml) increased from 52% in the lower quintile of IgE to 72% in the upper quintile (p < 0.01). After adjusting for age, gender, baseline percent predicted forced expiratory volume in 1 second, and smoking, the association between IgE (both in quintiles and continuous) and PC20 appeared consistent and statistically significant (p < 0.01). This association was stronger in patients who were not given inhaled steroid (odds ratio for twice the concentration of IgE, 1.42; 95% confidence interval, 1.09 and 1.84), than in patients treated with inhaled steroid (odds ratio, 1.10; 95% confidence interval, 0.82 and 1.50). Eosinophilia and skin reactivity were associated with PC20 although to a lesser extent. CONCLUSION: These findings strengthen the role played by IgE in facilitating the development of bronchial responsiveness in patients with asthma.

Administration, Inhalation↗
PubMed1995

[Compliance with nasal continuous positive airway pressure (CPAP) treatment in sleep apnea-hypopnea syndrome].

Ever since Sullivan introduced nighttime nasal continuous pressure on the upper airway (CPAP) in 1981 it has been the standard treatment for sleep-hypopnea syndrome (SAHS). However, CPAP is carried out at great expense and is not tolerated by all patients. Moreover, its efficacy is dependent on the degree of compliance. In this study we set out to analyze the degree of compliance with CPAP over the first 3 months of treatment in a group of 142 consecutive patients with moderate to severe SAHS (apnea-hypopnea index: 48.9 +/- 20). Diagnosis and measurement of the level of CPAP needed (9.6 +/- 2.5 cm H2O) were based on polysomnography. Eighteen (13%) patients did not return for follow-up evaluation. In the remaining 124 patients (age 54 +/- 11 years) compliance with treatment was evaluated by way of a sleep diary in which the patient recorded the hours CPAP was used at night; this record was compared with readings from the CPAP generator's counter. All subjects were asked about their degree of sleepiness before treatment by way of a standard questionnaire. Although most patients reported regular use of CPAP in diaries, only about 60% actually used it for longer than a mean 4.5 hours daily. The most compliant patients could not be differentiated from the least compliant with respect to degree of initial sleepiness, apnea-hypopnea-per-hour index or level of CPAP required.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Prognostic factors influencing the outcome in pneumocystis carinii pneumonia in patients with AIDS.

BACKGROUND: Studies attempting to identify the prognostic factors that influence the outcome of Pneumocystis carinii pneumonia (PCP) in patients with AIDS using a multivariate analysis are few. In order to identify those prognostic factors amenable to medical intervention, univariate and multivariate analyses were performed on 102 patients with AIDS suffering a first episode of PCP. METHODS: One hundred and two consecutive patients with AIDS (51% drug abusers, 45% homosexuals, and 4% with other HIV risk factors) admitted to our institution between 1986 and 1989 whose respiratory infection was diagnosed by bronchoalveolar lavage were studied prospectively. RESULTS: The overall mortality was 28%, rising to 79% in those patients who required mechanical ventilation. According to univariate analysis the following variables were related to a poor prognosis: age > 35 years; risk factor for HIV infection other than drug abuse; and AIDS diagnosis confirmed before 1988; PaO2 < 8 kPa at admission; severe acute respiratory failure on admission (PaO2/FIO2 < 20 kPa); mechanical ventilation; antibiotic therapy for PCP other than trimethoprim-sulphamethoxazole; multiple microbial pulmonary infection; serum lactate dehydrogenase (LDH) > 22.5 mukat/l on admission; serum albumin level < 30 g/l. Multivariate analysis showed that only mechanical ventilation was independently associated with a poor outcome. CONCLUSIONS: The mortality of AIDS patients presenting with a first episode of PCP before 1990 was high (28%). The main prognostic factor associated with poor outcome was the requirement for mechanical ventilation due to severe acute respiratory failure.

AIDS-Related Opportunistic Infections↗
PubMed1993

Specificity of endotracheal aspiration, protected specimen brush, and bronchoalveolar lavage in mechanically ventilated patients.

The specificity of the different techniques used to diagnose ventilator-associated pneumonia is still a matter of controversy. To investigate the specificity of endotracheal aspiration (EA), protected specimen brush (PSB), and bronchoalveolar lavage (BAL) quantitative cultures, we studied 27 consecutive mechanically ventilated (MV) patients (> 72 h) without clinical or radiographic evidence of pulmonary infection. Comparing different thresholds for quantitative cultures (from 10(3) through 10(6) CFU/ml), the lowest rate of false positive results was obtained using 10(6) for EA, 10(5) for PSB, and 10(6) for BAL. Using 10(6) CFU/ml for EA, 10(4) CFU/ml for PSB, and 10(5) CFU/ml for BAL as cutoff points, we obtained the following specificities: 85, 85, and 78% for the three techniques, respectively. A bacterial index of 8 was the best threshold to get a low percentage of false positive results for all techniques except for EA (0% for PSB and 12% for BAL). There were reasonable qualitative agreements (PSB versus EA = 58%; BAL versus EA = 69%; and PSB versus BAL = 62%) and poor quantitative correlations between concomitantly isolated microorganisms from the three types of samples. Quantitative cultures of EA, PSB, and BAL may show a considerable percentage of false positive results at the respective cutoff points usually accepted. Increasing the thresholds for quantitative cultures, albeit loosing sensitivity, may rule out better the absence of pulmonary infection in MV patients.

Bacteria↗
PubMed1992

Pulmonary aspiration of gastric contents in patients receiving mechanical ventilation: the effect of body position.

OBJECTIVE: To determine if the semirecumbent position (45-degree angle) decreases aspiration of gastric contents to the airways in intubated and mechanically ventilated patients. DESIGN: A randomized, two-period crossover trial. SETTING: Respiratory intensive care unit. PATIENTS: Nineteen patients requiring intubation and mechanical ventilation. INTERVENTIONS: Patients were studied in the supine and semirecumbent positions on two separate days. MEASUREMENTS: After technetium (Tc)-99m sulphur colloid labeling of gastric contents, sequential radioactive counts in endobronchial secretions were measured at 30-minute intervals over a 5-hour period. Samples of endobronchial secretions, gastric juice, and pharyngeal contents were obtained for qualitative bacterial cultures. RESULTS: Mean radioactive counts in endobronchial secretions were higher in samples obtained while patients were in the supine position than in those obtained while patients were in the semirecumbent position (4154 cpm compared with 954 cpm; P = 0.036). Moreover, the aspiration pattern was time-dependent for each position: For the supine position, radioactivity was 298 cpm at 30 min and 2592 cpm at 300 min (P = 0.013); for the semirecumbent position, radioactivity was 103 cpm at 30 min and 216 cpm at 300 min (P = 0.04). The same microorganisms were isolated from stomach, pharynx, and endobronchial samples in 32% of studies done while patients were semirecumbent and in 68% of studies done while patients were in the supine position. CONCLUSIONS: We conclude that the supine position and length of time the patient is kept in this position are potential risk factors for aspiration of gastric contents. Elevating the head of the bed for patients who can tolerate the semirecumbent position may be a simple, no-cost prophylactic measure.

Female↗
PubMed1992

The hepatopulmonary syndrome: new name, old complexities.

On the basis of previous work, our own experience and findings, and the considerations discussed above, we propose a set of four diagnostic criteria for the hepatopulmonary syndrome: 1. presence of chronic hepatic disease (alcoholic, postnecrotic, or primary biliary cirrhosis or active chronic hepatitis)--severe liver dysfunction may not be mandatory; 2. absence of intrinsic cardiopulmonary disease, with normal chest radiograph or with nodular basal shadowing; 3. pulmonary gas exchange abnormalities--an increased alveolar-arterial oxygen gradient (> or = 2.0 kPa) with or without hypoxaemia; 4. the extrapulmonary appearance of intravenous radiolabelled microspheres or a positive contrast enhanced echocardiogram, suggesting intrapulmonary vascular abnormalities. Although these four criteria appear straightforward, there may be other features that are not always present--namely: 1. low transfer factor (diffusing capacity); 2. shortness of breath, with or without platypnoea and orthodeoxia; 3. increased cardiac output and reduced pulmonary vascular pressures; 4. small (or no) increase in pulmonary vascular resistance when the patient is breathing low oxygen mixtures. From the physiological viewpoint, the hepatopulmonary syndrome provides an excellent model for clinical research in the pathophysiology of pulmonary gas exchange. So far it has been possible to show that arterial hypoxaemia in this condition is (1) partitioned into components resulting from VA/Q mismatching, intrapulmonary shunt, and limitations of oxygen diffusion; (2) modulated by the interplay between the intrapulmonary and the extrapulmonary determinants of PaO2, such as cardiac output and minute ventilation; (3) vulnerable to the influence of inadequate pulmonary vascular tone; and (4) resolved when the injured liver is replaced and hepatic function is restored to within normal limits.

Arteriovenous Anastomosis↗
PubMed1992

Risk factors of soybean epidemic asthma. The role of smoking and atopy.

Epidemics of emergency room admissions for asthma occurring in Barcelona during the period 1981 to 1987 were caused by inhalation of soybean dust. To investigate the risk factors that determined why some asthma patients became reactive to soybean and were consequently affected by the asthma epidemics of Barcelona but others did not do so, a case-control study was conducted during 1989, 2 yr after the cessation of asthma epidemics. Patients with asthma admitted in emergency room services during epidemic asthma days (n = 169) were compared with asthma patients admitted in the same services during nonepidemic days and who were never admitted during the epidemics (n = 147). Risk factors other than soybean exposure, namely skin reactivity against at least one common allergen (odds ratio [OR] 3.0, 1.7 to 5.3), age over 64 yr (OR 2.8, 1.4 to 6.0), cigarette smoking at the time of the epidemics (OR 2.3, 1.2 to 2.4), past smoking (OR 1.8, 0.9 to 3.7), and total immunoglobulin E (IgE) higher than 100 IU/ml (OR 1.7, 1.0 to 3.0), were found independently related to epidemic asthma. The role of smoking was especially important for those who had a positive skin reaction and were exposed to soybean dust (OR 7.9, 1.8 to 36.0). In this group, a dose-response pattern with pack-years was observed (p less than 0.01). The present findings suggest a multifactorial process for epidemic asthma, in which atopy and cigarette smoking played an important synergistic role. This has a preventive potential for IgE-related asthma.

Asthma↗
PubMed1992

Effect of intravenously administered aminophylline on ventilation/perfusion inequality during recovery from exacerbations of chronic obstructive pulmonary disease.

To investigate the effect of intravenously administered aminophylline and 100% O2 breathing on ventilation-perfusion (VA/Q) inequality, nine patients recovering from an acute exacerbation of chronic obstructive pulmonary disease (COPD) were studied. The design was double-blind, crossover, placebo-controlled for aminophylline, and a single-blind, controlled protocol for O2, patients being studied on two successive days. Forced spirometry, systemic hemodynamics, arterial pH, and blood gases were measured together with the VA/Q distribution using the multiple inert gas elimination technique, and then a loading dose of aminophylline (6 mg/kg body weight) or placebo was given over 20 min followed by a maintenance infusion at 0.9 mg/kg/h that was kept constant for the rest of the study. After 20 min of infusion the patient breathed either air or 100% O2 for another 30 min, and the measurements were repeated. Thereafter the inspired gas was shifted to the other FlO2 for 30 min, and a final set of measurements was made. The following day the procedure was repeated using the alternate drug. Aminophylline alone increased FVC and FEV1, but it produced no change in the group in ventilation, hemodynamics, blood gases, or the VA/Q distribution, although individual patients who had low VA/Q areas at baseline showed increases in these areas and worsening of log SD Q. Oxygen alone reduced cardiac output (QT) and caused modest further dispersion of the VA/Q distribution when compared with air breathing during placebo infusion (log SD Q 1.03 +/- 0.27 increased to 1.26 +/- 0.35, p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Incidence and etiology of pneumonia acquired during mechanical ventilation.

A total of 77 consecutive patients submitted to mechanical ventilation (MV) for greater than 48 h in a respiratory ICU (RICU) were studied to investigate the incidence, etiology, and consequences of ventilator-associated pneumonia. Eighteen (23%) patients developed a bacterial pneumonia after 5.6 +/- 1.0 days (mean +/- SEM; range 2 to 17) of MV. Three additional cases were demonstrated at autopsy, raising the incidence to 27%. Overall, the mean duration of MV increased from 9.7 +/- 0.9 to 32.2 +/- 5.1 days (p less than .0001) when pneumonia developed. A longer period of hospital stay before RICU admission and the presence of chronic obstructive pulmonary disease were significant characteristics of patients with pneumonia when compared to patients without nosocomial pulmonary infection. One or more etiological agents were identified in 14 patients from the pneumonia group by means of a highly specific technique (protected brush catheter, transthoracic needle aspiration, pleural fluid, and/or blood cultures). The predominant pathogens isolated were Gram-negative bacilli (Acinetobacter sp. and Pseudomonas sp.). Half of the cases were polymicrobial. Compared to other series, our results may reflect with more accuracy the actual incidence of nosocomial pneumonia in mechanically ventilated patients, since we used highly accurate techniques along with autopsy findings which allowed us to confirm or discard the diagnosis of bacterial pneumonia.

Cross Infection↗
PubMed1989

Diagnostic value of quantitative cultures of bronchoalveolar lavage and telescoping plugged catheters in mechanically ventilated patients with bacterial pneumonia.

We compared the diagnostic value of quantitative cultures of bronchoalveolar lavage (BAL) and telescoping plugged catheter (TPC) samples in 34 nonimmunocompromised, mechanically ventilated (MV) patients with suspected bacterial pneumonia. A control group of seven "noninfected" MV patients was also studied. In 92% of patients with bacterial pneumonia (32 of 34), simple endotracheal aspiration samples recovered one or more microorganisms. Both BAL and TPC samples cultured colony-forming units (cfu) greater than or equal to 10(3)/ml of one or more microorganisms in 56% (19 of 34) of patients. TPC and BAL culture results agreed on 88.5% (54 of 61) of the recovered microorganisms. Sterile TPC and BAL cultures agreed on 80% (4 of 5) of the cases. Microorganisms cultured from blood samples were also cultured from BAL and TPC specimens. Culture results from the two techniques completely disagreed in only one case (3%). In the control group, one TPC and two BAL cultures yielded microorganisms in cfu greater than or equal to 10(3)/ml. Specificities of BAL and TPC were 71 and 86%, respectively, whereas specificity of endotracheal aspiration was only 14%. Both the bacterial index obtained by TPC and BAL, as well as the quantitative cultures, correlated moderately well (r = 0.78 and 0.72, respectively, p less than 0.001 for both correlations). BAL and TPC results caused changes of antibiotic treatment in 11 of 23 survivors. Neither BAL nor TPC caused complications. Our results demonstrate that BAL and TPC diagnose bacterial pneumonia in MV patients with similar accuracy. Culture results from both techniques showed excellent qualitative and reasonable quantitative agreement.

Adult↗
PubMed1989

Lung function in allogeneic bone marrow transplantation recipients.

In order to investigate the incidence of pulmonary function complications following bone marrow transplantation (BMT), 17 patients with leukaemia and 8 with aplastic anaemia were sequentially assessed over a one year period. Before BMT, all the patients were free of respiratory symptoms and had both normal chest X-ray and routine lung function tests. However, 5 patients disclosed airway hyperreactivity. Aplastic anaemia patients had significantly lower haemoglobin-adjusted diffusing capacity for carbon monoxide (DLCO) than those with leukaemia, a finding significantly related to the lower haemoglobin values shown in the former individuals. Following BMT there were transient mild to moderate reductions in DLCO and static lung volumes; moreover, patients with leukaemia had lower DLCO than those with aplastic anaemia. Fourteen of the 25 patients had ventilatory defects, including 10 individuals with bronchial hyperresponsiveness. Post-BMT lung function changes were transiently accompanied by mild to moderate symptoms of respiratory disease in most of the patients.

Adult↗
PubMed1988

Nosocomial pneumonia. A multivariate analysis of risk and prognosis.

One hundred and twenty consecutive episodes of nosocomial pneumonia (NP) in 118 nonneutropenic adults admitted to a 1,000-bed teaching hospital were studied in order to investigate the prognosis and risk factors. The overall fatality rate was 36.6 percent. The identification of a "high-risk" microorganism (Pseudomonas aeruginosa, Enterobacteriaceae, and other Gram-negative bacilli, Streptococcus faecalis, Staphylococcus aureus, Candida sp, Aspergillus sp, and episodes of polymicrobial pneumonia), bilateral involvement on chest x-ray examination, the presence of respiratory failure, inappropriate antibiotic therapy, and age older than 60 years or an underlying condition ultimately or rapidly fatal were those factors selected by a stepforward logistic regression analysis as independently worsening the prognosis. A series of variables frequently quoted as predisposing to NP was determined to be either present or absent in the same 120 cases of NP and in an equal number of randomly selected control subjects. After adjusting for confounding, factors significantly predisposing to NP were tracheal intubation, depressed level of consciousness, underlying chronic lung disease, thoracic or upper abdominal surgery, prior episode of a large volume aspiration, and age older than 70 years. Since some of the factors influencing the risk or the prognosis of NP are amenable to medical intervention, a percentage of NP might be prevented and its prognosis can be improved.

Adult↗
PubMed1986

[Determination of the distribution of ventilation-perfusion ratios: technic of elimination of multiple inert gases].

The multiple inert gas elimination technique (MIGT) facilitates the estimation of the distributions of ventilation-perfusion (VA/Q) ratios in the experimental and clinical setting. The most relevant technical aspects and equipment and operational requirements needed to measure a mixture of inert gases in both the gas phase and the blood phase using gas chromatography are overviewed with detail. Results obtained in 3 dogs and 4 syringe-homogeneous lung models were entirely consistent with data formerly reported in the literature. Particular attention is paid to the linearity of the gas chromatograph detectors, reproducibility of inert gases sampling, and analysis of brands of heparin to detect acetone content. The errors of measurement (coefficients of variation) in blood were: 1.4 for sulfur hexafluoride; 1.8% for ethane; 2% for cyclopropane and halothane, each; 2.4% for diethyl ether; and, 3.6% for acetone. Important practical points are also emphasized in order to draw attention to potential problems and issues that should be concentrated upon to minimize the error in the measurements. It is concluded that the setting up of the MIGT is well established and validated.

Animals↗
PubMed1983

[Asbestos!].

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Asbestos↗