R. Rodriguez-roisin - Academia.edu (original) (raw)
Papers by R. Rodriguez-roisin
Archivos de Bronconeumología, 1985
Update in Intensive Care and Emergency Medicine, 1995
Monaldi archives for chest disease = Archivio Monaldi per le malattie del torace / Fondazione clinica del lavoro, IRCCS [and] Istituto di clinica tisiologica e malattie apparato respiratorio, Università di Napoli, Secondo ateneo, 1997
Chronic Obstructive Pulmonary Disease, 2007
Page 1. CHAPTER 9 The physiology of gas exchange Robert Rodriguez-Roisin, Andrés Echazarreta, Fed... more Page 1. CHAPTER 9 The physiology of gas exchange Robert Rodriguez-Roisin, Andrés Echazarreta, Federico P. Gómez and Joan Albert Barberà The major goal of the respiratory system is to exchange physiological (respiratory ...
… in Chronic Obstructive …, 2003
... 28. Marvin PM, Baker BJ, Dutt AK, Murphy ML, Bone RC. Physiologic effects of oral bronchodila... more ... 28. Marvin PM, Baker BJ, Dutt AK, Murphy ML, Bone RC. Physiologic effects of oral bronchodilators during rest and exercise in chronic obstructive pulmonary disease. ... Am Rev Respir Dis 1975; 112: 371376. 49. Leitch AG, Hopkin JM, Ellis DA, Merchant S, McHardy GJ. ...
Neutrophil airway influx by platelet-activating factor in asthma: role of adhesion molecules and ... more Neutrophil airway influx by platelet-activating factor in asthma: role of adhesion molecules and LTB 4 expression. ABSTRACT: Platelet-activating factor (PAF)-induced neutrophil lung sequestration may require cell surface adhesion molecules (macrophage-1 antigen (MAC-1) and lymphocyte function-associated antigen-1 (LFA-1)). In this randomised, double-blinded, crossover study, the neutrophil kinetics after PAF and Lyso-PAF (L-PAF) airway challenge were investigated in nine mild-intermittent asthmatics. Neutrophils were measured in peripheral blood (PB) before and at 5, 15, 45 and 240 min after bronchoprovocation, and in induced sputum before and at 240 min after challenge. MAC-1 and LFA-1 expression were assessed by immunocytochemistry, and leukotriene B 4 (LTB 4) was measured by enzyme-immunoassay in induced-sputum supernatants. Compared with baseline, neutrophils in PB decreased 5 min after PAF, while at 240 min neutrophils in induced sputum increased. Compared with baseline and L-PAF, PAF decreased the percentages of MAC-1-and LFA-1-positive neutrophils in PB at 5 min, but increased the percentages of MAC-1 and LFA-1 in neutrophil-induced sputum. Moreover, compared with baseline and L-PAF, PAF-induced sputum revealed higher LTB 4 levels, a finding that correlated with the elevated number of neutrophils in induced sputum. These findings suggest that macrophage-1 antigen and lymphocyte function-associated antigen-1 are involved in platelet-activating factor-induced neutrophil lung traffic, and that this process is modulated by enhanced leukotriene B 4 release within the airways.
Journal of Clinical Gastroenterology, 1987
The association of pulmonary fibrosis and primary biliary cirrhosis (PBC) remains controversial. ... more The association of pulmonary fibrosis and primary biliary cirrhosis (PBC) remains controversial. To determine the frequency of pulmonary fibrosis in PBC, a carefully selected series of 14 PBC patients, seven patients with Sicca complex, and 14 control subjects have been studied. Seven of the 14 patients with PBC had Sjogren's syndrome, four of whom had some clinical evidence of pulmonary disease. Evaluation of ventilatory capacity, gas transfer factor, arterial blood gases, and lung mechanics were performed. Gas transfer was reduced in patients with PBC associated with Sj6gren's syndrome and in patients with the Sicca complex. These results suggest that the respiratory, clinical, and functional abnormalities found in PBC are related to the presence of an associated Sjogren's syndrome.
Reviews, 1996
Many patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated wi... more Many patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated with antibiotics. However, the value of antibiotics remains uncertain as systematic reviews and clinical trials have shown conflicting results. To assess the effects of antibiotics in the management of acute COPD exacerbations on treatment failure as observed between seven days and one month after treatment initiation (primary outcome) and on other patient-important outcomes (mortality, adverse events, length of hospital stay). We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and other electronically available databases up to September 2012. Randomised controlled trials (RCTs) in people with acute COPD exacerbations comparing antibiotic therapy and placebo with a follow-up of at least seven days. Two review authors independently screened references and extracted data from trial reports. We kept the three groups of outpatients, inpatients and patients admitted to the intensive care unit (ICU) separate for benefit outcomes and mortality because we considered them to be clinically too different to be summarised in one group. We considered outpatients to have a mild to moderate exacerbation, inpatients to have a severe exacerbation and ICU patients to have a very severe exacerbation. Where outcomes or study details were not reported we requested missing data from the authors of the primary studies. We calculated pooled risk ratios (RR) for treatment failure, Peto odds ratios (OR) for rare events (mortality and adverse events) and weighted mean differences (MD) for continuous outcomes using fixed-effect models. We used GRADE to assess the quality of the evidence. Sixteen trials with 2068 participants were included. In outpatients (mild to moderate exacerbations), there was evidence of low quality that antibiotics did statistically significantly reduce the risk for treatment failure between seven days and one month after treatment initiation (RR 0.75; 95% CI 0.60 to 0.94; I(2) = 35%) but they did not significantly reduce the risk when the meta-analysis was restricted to currently available drugs (RR 0.80; 95% CI 0.63 to 1.01; I(2) = 33%). Evidence of high quality showed that antibiotics statistically significantly reduced the risk of treatment failure in inpatients with severe exacerbations (ICU not included) (RR 0.77; 95% CI 0.65 to 0.91; I(2) = 47%) regardless of whether restricted to current drugs. The only trial with 93 patients admitted to the ICU showed a large and statistically significant effect on treatment failure (RR 0.19; 95% CI 0.08 to 0.45; high-quality evidence).Evidence of low-quality from four trials in inpatients showed no effect of antibiotics on mortality (Peto OR 1.02; 95% CI 0.37 to 2.79). High-quality evidence from one trial showed a statistically significant effect on mortality in ICU patients (Peto OR 0.21; 95% CI 0.06 to 0.72). Length of hospital stay (in days) was similar in the antibiotics and placebo groups except for the ICU study where antibiotics statistically significantly reduced length of hospital stay (mean difference -9.60 days; 95% CI -12.84 to -6.36 days). One trial showed no effect of antibiotics on re-exacerbations between two and six weeks after treatment initiation. Only one trial (N = 35) reported health-related quality of life but did not show a statistically significant difference between the treatment and control group.Evidence of moderate quality showed that the overall incidence of adverse events was higher in the antibiotics groups (Peto OR 1.53; 95% CI 1.03 to 2.27). Patients treated with antibiotics experienced statistically significantly more diarrhoea based on three trials (Peto OR 2.62; 95% CI 1.11 to 6.17; high-quality evidence). Antibiotics for COPD exacerbations showed large and consistent beneficial effects across outcomes of patients admitted to an ICU. However, for outpatients and inpatients the results were inconsistent. The risk for treatment failure was significantly reduced in both inpatients and outpatients when all trials (1957 to 2012) were included but not when the analysis for outpatients was restricted to currently used antibiotics. Also, antibiotics had no statistically significant effect on mortality and length of hospital stay in inpatients and almost no data on patient-reported outcomes exist. These inconsistent effects call for research into clinical signs and biomarkers that help identify patients who benefit from antibiotics and patients who experience no effect, and in whom downsides of antibiotics (side effects, costs and multi-resistance) could be avoided.
European Respiratory Review, 2006
ABSTRACT
11th Annual meeting of the EBMT, 1985
Respiratory medicine, 2000
Several studies have been carried out to clarify the relationship between CD30 expression and Th2... more Several studies have been carried out to clarify the relationship between CD30 expression and Th2 lymphocytes, although the results have been controversial. To investigate whether CD30 is a useful marker for Th2 lymphocytes in bronchoalveolar lavage (BAL) in interstitial lung diseases (ILD), we studied six control subjects and 31 patients with ILD (12 with idiopathic pulmonary fibrosis, seven with hypersensitivity pneumonitis, three with chronic eosinophilic pneumonia and nine with sarcoidosis). The levels of interleukin-5 (IL-5) (secreted by Th2 cells), interferon-gamma (IFNgamma) (secreted by Th1 cells) and the expression of CD30 on lymphocytes were determined in BAL fluid. There were no differences in the percentage of CD30+ lymphocytes between controls and patients with ILD (0.8+0.4% vs. 2+/-0.4%). In order to determine the relationship between Th2 cells and CD30 expression, we divided the patients into two groups according to BAL IL-5 levels. Group I consisted of eight patients...
Zhonghua yi xue za zhi, Jan 10, 2012
Journal of applied physiology (Bethesda, Md. : 1985), 1994
To examine whether the tip of the femoral vein catheter used for sampling femoral venous PO2 duri... more To examine whether the tip of the femoral vein catheter used for sampling femoral venous PO2 during cycling exercise is contaminated by skin or saphenous vein blood, we studied 6 healthy volunteers [21.7 +/- 0.7 (SD) yr] during three identical incremental exercise tests while breathing room air on the same day. Femoral venous blood was sampled simultaneously from two catheters inserted into the femoral vein but advanced in opposite directions (7 cm distally and 5 cm proximally). Blood sampling for measurements of PO2, PCO2, pH, hemoglobin concentration, and oxyhemoglobin saturation was done simultaneously from both catheters in duplicate at rest, at 60% of maximum workload (60% W), and at maximum symptom-limited exercise (100% W). Temperature was measured with a thermistor probe placed in the proximal catheter. At rest, distal PO2 was significantly lower than that measured proximally (24.9 +/- 4.3 vs 30.8 +/- 6.1 mmHg, respectively; P < 0.004), but no differences were found durin...
European journal of respiratory diseases, 1983
A prospective study was carried out in 26 patients intubated and mechanically ventilated for seve... more A prospective study was carried out in 26 patients intubated and mechanically ventilated for severe exacerbation of asthma. The age of onset of asthma and the duration of disease showed wide variations, but most of the patients were women in their fifties with chronic asthma. However, 23% had the more benign intermittent course. Most patients had a prodromal period of several days with progressive deterioration. Eight patients developed sudden attacks, in three of them aspirin-intolerance was responsible, in two patients emotional disturbances could play some role as triggering factors, and in three other patients no obvious reason was found. Identification of factors responsible for the sudden attacks may be relevant to the management of these severe cases. The majority of patients were intubated immediately on arrival or during the first hours after admission. Deaths were related to complications produced by hypoxia, or hospitalization in an intensive care unit. Probably many of t...
The American review of respiratory disease, 1984
Hypoxemia during hemodialysis has variously been attributed to worsening ventilation-perfusion (V... more Hypoxemia during hemodialysis has variously been attributed to worsening ventilation-perfusion (VA/Q) relationships, alveolar hypoventilation combined with a reduced respiratory quotient, increased right-to-left shunting, and diffusion impairment. It is difficult to separate out these various effects, which explains lack of agreement in the literature. To more critically evaluate the causes of hypoxemia during hemodialysis, we used a multiple inert gas elimination technique to determine the distribution of ventilation-perfusion ratios during hemodialysis in 8 patients with chronic renal failure. Measurements were made before, during (at 60, 120, and 210 min), and after hemodialysis. Whereas arterial PO2 fell from 87 to 74 mmHg by 120 min, ventilation-perfusion relationships actually improved. Cardiac output fell from 5.3 to 4.0 L/min over the same time. Alveolar ventilation, respiratory quotient, and alveolar PO2 all fell, and the alveolar arterial PO2 difference remained essentiall...
Thorax, 1986
To investigate whether the effects of nifedipine on methacholine induced broncho-constriction cou... more To investigate whether the effects of nifedipine on methacholine induced broncho-constriction could impair pulmonary gas exchange in bronchial asthma a randomised, double blind, crossover study in 13 symptom free asthmatic subjects was designed. Each patient underwent a methacholine bronchial challenge test on two separate days one week apart, after having either oral nifedipine (20 mg thrice daily) or placebo for three days. Arterial blood gases were measured before and after methacholine challenge in nine subjects. Prechallenge values of forced expiratory volume in one second (FEV1) and arterial oxygen tension (Pao2) were similar after nifedipine and after placebo. After challenge, the cumulative doses of methacholine required to produce a 20% fall in FEV1 (PD20 FEV1) were significantly larger after nifedipine (280 (SD 347)) cumulative breath units (CBU) than after placebo (120 (183) CBU; p less than 0.01). After challenge the fall in Pao2 values (17.1 (1.6) mm Hg; (2.28 (0.21) kP...
Bulletin européen de physiopathologie respiratoire
It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patien... more It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patients with chronic obstructive pulmonary disease (COPD) with associated respiratory failure, through the release of hypoxic pulmonary vasoconstriction. To investigate the effects of naloxone on gas exchange, seven clinically stable patients with severe COPD (type B) (forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 38.3 +/- 4.0%) with hypoxaemia and hypercapnia (PaO2 7.6 +/- 0.4 kPa; PaCO2 6.4 +/- 0.3; pH 7.37 +/- 0.02), aged 59.0 +/- 4.6 yr, were studied. Breathing patterns, haemodynamic and conventional and inert gas exchange measurements were made while breathing room air before, during and 60 min after i.v. naloxone infusion. Naloxone and catecholamine plasma levels were also determined. In three subjects (protocol A), measurements were made using increasing concentrations of naloxone (cumulative dose: 54 mg), while the remaining four patients were studied (protoc...
Archivos de Bronconeumología, 1985
Update in Intensive Care and Emergency Medicine, 1995
Monaldi archives for chest disease = Archivio Monaldi per le malattie del torace / Fondazione clinica del lavoro, IRCCS [and] Istituto di clinica tisiologica e malattie apparato respiratorio, Università di Napoli, Secondo ateneo, 1997
Chronic Obstructive Pulmonary Disease, 2007
Page 1. CHAPTER 9 The physiology of gas exchange Robert Rodriguez-Roisin, Andrés Echazarreta, Fed... more Page 1. CHAPTER 9 The physiology of gas exchange Robert Rodriguez-Roisin, Andrés Echazarreta, Federico P. Gómez and Joan Albert Barberà The major goal of the respiratory system is to exchange physiological (respiratory ...
… in Chronic Obstructive …, 2003
... 28. Marvin PM, Baker BJ, Dutt AK, Murphy ML, Bone RC. Physiologic effects of oral bronchodila... more ... 28. Marvin PM, Baker BJ, Dutt AK, Murphy ML, Bone RC. Physiologic effects of oral bronchodilators during rest and exercise in chronic obstructive pulmonary disease. ... Am Rev Respir Dis 1975; 112: 371376. 49. Leitch AG, Hopkin JM, Ellis DA, Merchant S, McHardy GJ. ...
Neutrophil airway influx by platelet-activating factor in asthma: role of adhesion molecules and ... more Neutrophil airway influx by platelet-activating factor in asthma: role of adhesion molecules and LTB 4 expression. ABSTRACT: Platelet-activating factor (PAF)-induced neutrophil lung sequestration may require cell surface adhesion molecules (macrophage-1 antigen (MAC-1) and lymphocyte function-associated antigen-1 (LFA-1)). In this randomised, double-blinded, crossover study, the neutrophil kinetics after PAF and Lyso-PAF (L-PAF) airway challenge were investigated in nine mild-intermittent asthmatics. Neutrophils were measured in peripheral blood (PB) before and at 5, 15, 45 and 240 min after bronchoprovocation, and in induced sputum before and at 240 min after challenge. MAC-1 and LFA-1 expression were assessed by immunocytochemistry, and leukotriene B 4 (LTB 4) was measured by enzyme-immunoassay in induced-sputum supernatants. Compared with baseline, neutrophils in PB decreased 5 min after PAF, while at 240 min neutrophils in induced sputum increased. Compared with baseline and L-PAF, PAF decreased the percentages of MAC-1-and LFA-1-positive neutrophils in PB at 5 min, but increased the percentages of MAC-1 and LFA-1 in neutrophil-induced sputum. Moreover, compared with baseline and L-PAF, PAF-induced sputum revealed higher LTB 4 levels, a finding that correlated with the elevated number of neutrophils in induced sputum. These findings suggest that macrophage-1 antigen and lymphocyte function-associated antigen-1 are involved in platelet-activating factor-induced neutrophil lung traffic, and that this process is modulated by enhanced leukotriene B 4 release within the airways.
Journal of Clinical Gastroenterology, 1987
The association of pulmonary fibrosis and primary biliary cirrhosis (PBC) remains controversial. ... more The association of pulmonary fibrosis and primary biliary cirrhosis (PBC) remains controversial. To determine the frequency of pulmonary fibrosis in PBC, a carefully selected series of 14 PBC patients, seven patients with Sicca complex, and 14 control subjects have been studied. Seven of the 14 patients with PBC had Sjogren's syndrome, four of whom had some clinical evidence of pulmonary disease. Evaluation of ventilatory capacity, gas transfer factor, arterial blood gases, and lung mechanics were performed. Gas transfer was reduced in patients with PBC associated with Sj6gren's syndrome and in patients with the Sicca complex. These results suggest that the respiratory, clinical, and functional abnormalities found in PBC are related to the presence of an associated Sjogren's syndrome.
Reviews, 1996
Many patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated wi... more Many patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated with antibiotics. However, the value of antibiotics remains uncertain as systematic reviews and clinical trials have shown conflicting results. To assess the effects of antibiotics in the management of acute COPD exacerbations on treatment failure as observed between seven days and one month after treatment initiation (primary outcome) and on other patient-important outcomes (mortality, adverse events, length of hospital stay). We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and other electronically available databases up to September 2012. Randomised controlled trials (RCTs) in people with acute COPD exacerbations comparing antibiotic therapy and placebo with a follow-up of at least seven days. Two review authors independently screened references and extracted data from trial reports. We kept the three groups of outpatients, inpatients and patients admitted to the intensive care unit (ICU) separate for benefit outcomes and mortality because we considered them to be clinically too different to be summarised in one group. We considered outpatients to have a mild to moderate exacerbation, inpatients to have a severe exacerbation and ICU patients to have a very severe exacerbation. Where outcomes or study details were not reported we requested missing data from the authors of the primary studies. We calculated pooled risk ratios (RR) for treatment failure, Peto odds ratios (OR) for rare events (mortality and adverse events) and weighted mean differences (MD) for continuous outcomes using fixed-effect models. We used GRADE to assess the quality of the evidence. Sixteen trials with 2068 participants were included. In outpatients (mild to moderate exacerbations), there was evidence of low quality that antibiotics did statistically significantly reduce the risk for treatment failure between seven days and one month after treatment initiation (RR 0.75; 95% CI 0.60 to 0.94; I(2) = 35%) but they did not significantly reduce the risk when the meta-analysis was restricted to currently available drugs (RR 0.80; 95% CI 0.63 to 1.01; I(2) = 33%). Evidence of high quality showed that antibiotics statistically significantly reduced the risk of treatment failure in inpatients with severe exacerbations (ICU not included) (RR 0.77; 95% CI 0.65 to 0.91; I(2) = 47%) regardless of whether restricted to current drugs. The only trial with 93 patients admitted to the ICU showed a large and statistically significant effect on treatment failure (RR 0.19; 95% CI 0.08 to 0.45; high-quality evidence).Evidence of low-quality from four trials in inpatients showed no effect of antibiotics on mortality (Peto OR 1.02; 95% CI 0.37 to 2.79). High-quality evidence from one trial showed a statistically significant effect on mortality in ICU patients (Peto OR 0.21; 95% CI 0.06 to 0.72). Length of hospital stay (in days) was similar in the antibiotics and placebo groups except for the ICU study where antibiotics statistically significantly reduced length of hospital stay (mean difference -9.60 days; 95% CI -12.84 to -6.36 days). One trial showed no effect of antibiotics on re-exacerbations between two and six weeks after treatment initiation. Only one trial (N = 35) reported health-related quality of life but did not show a statistically significant difference between the treatment and control group.Evidence of moderate quality showed that the overall incidence of adverse events was higher in the antibiotics groups (Peto OR 1.53; 95% CI 1.03 to 2.27). Patients treated with antibiotics experienced statistically significantly more diarrhoea based on three trials (Peto OR 2.62; 95% CI 1.11 to 6.17; high-quality evidence). Antibiotics for COPD exacerbations showed large and consistent beneficial effects across outcomes of patients admitted to an ICU. However, for outpatients and inpatients the results were inconsistent. The risk for treatment failure was significantly reduced in both inpatients and outpatients when all trials (1957 to 2012) were included but not when the analysis for outpatients was restricted to currently used antibiotics. Also, antibiotics had no statistically significant effect on mortality and length of hospital stay in inpatients and almost no data on patient-reported outcomes exist. These inconsistent effects call for research into clinical signs and biomarkers that help identify patients who benefit from antibiotics and patients who experience no effect, and in whom downsides of antibiotics (side effects, costs and multi-resistance) could be avoided.
European Respiratory Review, 2006
ABSTRACT
11th Annual meeting of the EBMT, 1985
Respiratory medicine, 2000
Several studies have been carried out to clarify the relationship between CD30 expression and Th2... more Several studies have been carried out to clarify the relationship between CD30 expression and Th2 lymphocytes, although the results have been controversial. To investigate whether CD30 is a useful marker for Th2 lymphocytes in bronchoalveolar lavage (BAL) in interstitial lung diseases (ILD), we studied six control subjects and 31 patients with ILD (12 with idiopathic pulmonary fibrosis, seven with hypersensitivity pneumonitis, three with chronic eosinophilic pneumonia and nine with sarcoidosis). The levels of interleukin-5 (IL-5) (secreted by Th2 cells), interferon-gamma (IFNgamma) (secreted by Th1 cells) and the expression of CD30 on lymphocytes were determined in BAL fluid. There were no differences in the percentage of CD30+ lymphocytes between controls and patients with ILD (0.8+0.4% vs. 2+/-0.4%). In order to determine the relationship between Th2 cells and CD30 expression, we divided the patients into two groups according to BAL IL-5 levels. Group I consisted of eight patients...
Zhonghua yi xue za zhi, Jan 10, 2012
Journal of applied physiology (Bethesda, Md. : 1985), 1994
To examine whether the tip of the femoral vein catheter used for sampling femoral venous PO2 duri... more To examine whether the tip of the femoral vein catheter used for sampling femoral venous PO2 during cycling exercise is contaminated by skin or saphenous vein blood, we studied 6 healthy volunteers [21.7 +/- 0.7 (SD) yr] during three identical incremental exercise tests while breathing room air on the same day. Femoral venous blood was sampled simultaneously from two catheters inserted into the femoral vein but advanced in opposite directions (7 cm distally and 5 cm proximally). Blood sampling for measurements of PO2, PCO2, pH, hemoglobin concentration, and oxyhemoglobin saturation was done simultaneously from both catheters in duplicate at rest, at 60% of maximum workload (60% W), and at maximum symptom-limited exercise (100% W). Temperature was measured with a thermistor probe placed in the proximal catheter. At rest, distal PO2 was significantly lower than that measured proximally (24.9 +/- 4.3 vs 30.8 +/- 6.1 mmHg, respectively; P < 0.004), but no differences were found durin...
European journal of respiratory diseases, 1983
A prospective study was carried out in 26 patients intubated and mechanically ventilated for seve... more A prospective study was carried out in 26 patients intubated and mechanically ventilated for severe exacerbation of asthma. The age of onset of asthma and the duration of disease showed wide variations, but most of the patients were women in their fifties with chronic asthma. However, 23% had the more benign intermittent course. Most patients had a prodromal period of several days with progressive deterioration. Eight patients developed sudden attacks, in three of them aspirin-intolerance was responsible, in two patients emotional disturbances could play some role as triggering factors, and in three other patients no obvious reason was found. Identification of factors responsible for the sudden attacks may be relevant to the management of these severe cases. The majority of patients were intubated immediately on arrival or during the first hours after admission. Deaths were related to complications produced by hypoxia, or hospitalization in an intensive care unit. Probably many of t...
The American review of respiratory disease, 1984
Hypoxemia during hemodialysis has variously been attributed to worsening ventilation-perfusion (V... more Hypoxemia during hemodialysis has variously been attributed to worsening ventilation-perfusion (VA/Q) relationships, alveolar hypoventilation combined with a reduced respiratory quotient, increased right-to-left shunting, and diffusion impairment. It is difficult to separate out these various effects, which explains lack of agreement in the literature. To more critically evaluate the causes of hypoxemia during hemodialysis, we used a multiple inert gas elimination technique to determine the distribution of ventilation-perfusion ratios during hemodialysis in 8 patients with chronic renal failure. Measurements were made before, during (at 60, 120, and 210 min), and after hemodialysis. Whereas arterial PO2 fell from 87 to 74 mmHg by 120 min, ventilation-perfusion relationships actually improved. Cardiac output fell from 5.3 to 4.0 L/min over the same time. Alveolar ventilation, respiratory quotient, and alveolar PO2 all fell, and the alveolar arterial PO2 difference remained essentiall...
Thorax, 1986
To investigate whether the effects of nifedipine on methacholine induced broncho-constriction cou... more To investigate whether the effects of nifedipine on methacholine induced broncho-constriction could impair pulmonary gas exchange in bronchial asthma a randomised, double blind, crossover study in 13 symptom free asthmatic subjects was designed. Each patient underwent a methacholine bronchial challenge test on two separate days one week apart, after having either oral nifedipine (20 mg thrice daily) or placebo for three days. Arterial blood gases were measured before and after methacholine challenge in nine subjects. Prechallenge values of forced expiratory volume in one second (FEV1) and arterial oxygen tension (Pao2) were similar after nifedipine and after placebo. After challenge, the cumulative doses of methacholine required to produce a 20% fall in FEV1 (PD20 FEV1) were significantly larger after nifedipine (280 (SD 347)) cumulative breath units (CBU) than after placebo (120 (183) CBU; p less than 0.01). After challenge the fall in Pao2 values (17.1 (1.6) mm Hg; (2.28 (0.21) kP...
Bulletin européen de physiopathologie respiratoire
It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patien... more It has been hypothesized that naloxone may alter the ventilation-perfusion relationship in patients with chronic obstructive pulmonary disease (COPD) with associated respiratory failure, through the release of hypoxic pulmonary vasoconstriction. To investigate the effects of naloxone on gas exchange, seven clinically stable patients with severe COPD (type B) (forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 38.3 +/- 4.0%) with hypoxaemia and hypercapnia (PaO2 7.6 +/- 0.4 kPa; PaCO2 6.4 +/- 0.3; pH 7.37 +/- 0.02), aged 59.0 +/- 4.6 yr, were studied. Breathing patterns, haemodynamic and conventional and inert gas exchange measurements were made while breathing room air before, during and 60 min after i.v. naloxone infusion. Naloxone and catecholamine plasma levels were also determined. In three subjects (protocol A), measurements were made using increasing concentrations of naloxone (cumulative dose: 54 mg), while the remaining four patients were studied (protoc...