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Biomedical subjects

R Rodriguez-Roisin

Publications and source records attributed to R Rodriguez-Roisin.

At least 73 records · Page 4Linked to original sources
PubMed1996

Bacterial colonization as a potential source of nosocomial respiratory infections in two types of spirometer.

The potential risk of spirometers in the transmission of respiratory infections has not been yet established. We performed a prospective cross-sectional study to determine the rate of colonization of a water-sealed spirometer and a pneumotachograph, and the potential risk of cross-transmission of microorganisms to patients using each of these devices. Fifty four patients (aged 51 +/- 18 (mean +/- SD) yrs) were included in the study. All of them had undergone forced spirometry with bronchodilator response by means of the water-sealed spirometer (n = 36) or the pneumotachograph (n = 18). None had a clinically apparent respiratory infection at the time of the study. Routine hygiene measures for respiratory equipment were performed before the study protocol. Samples for microbiological cultures of different parts both of the water-sealed spirometer (proximal and distal tubing, bell and water-bell) and pneumotachograph (proximal and distal tubing) were taken daily before and after the usual series of lung function tests during a 5 day period. Pharyngeal swab cultures were obtained before spirometry and 7 days later in each subject. Thirty six out of a total of 40 (90%) culture samples from the water-sealed spirometer showed microbial growth compared to 4 out of 30 (13%) samples obtained from the pneumotachograph (p < 0.0001). Significant colonization of the water-sealed spirometer was apparent after the third day of the study. The microorganisms most frequently isolated were penicillium sp. (62%), Pseudomonas fluorescens (32%), and Burkholderia cepacea (48%). Distal tubing, water and water-bell were the parts of the water-sealed spirometer that showed higher colonization counts (> or = 10(4) colony-forming units (cfu).mL-1). No transmission sequence of potentially pathogenic microorganisms from equipment to patients or vice versa could be demonstrated. In summary, the water-sealed spirometer frequently became colonized by microorganisms. The potential hazard of such equipment as reservoirs of microorganisms suggests a need for the implementation of new hygiene measures for their maintenance.

Bacterial Infections↗
PubMed1996

Ventilation-perfusion response after fenoterol in hypoxemic patients with stable COPD.

BACKGROUND: The effects of vasoactive drugs, including bronchodilators, on vascular and pulmonary dynamics are interrelated, complex and difficult to measure, but important because of potential deleterious effects on gas exchange. METHODS: To assess the effects of fenoterol at both high and low dose on pulmonary gas exchange in 24 hypoxemic patients with stable COPD: fenoterol, 5 mg; fenoterol, 1 mg and ipratropium bromide, 0.5 mg; ipratropium bromide, 0.5 mg; or matched placebo were nebulized in a double-blind, placebo-controlled fashion. Spirometry, ventilation, systemic hemodynamics, and respiratory and inert gases were measured before and 15, 60, and 120 min after each treatment. RESULTS: Compared with placebo, heart rate (p < 0.002) and cardiac output (p = 0.05) increased after high-dose fenoterol therapy to return to baseline values by 120 min. Following fenoterol at high dose, mean maximum PaO2 change from baseline decreased by 6.3 +/- 1.1 mm Hg (SD) and both alveolararterial oxygen pressure difference (P[A-a]O2), by 8.3 +/- 4.0 mm Hg, and ventilation-perfusion (VA/Q) mismatching increased, as evidenced by increments of the dispersion of pulmonary blood flow, without reaching significance; likewise, low-dose fenoterol therapy increased VA/Q inequalities while both PaO2 and P(A-a)O2 remained unchanged. CONCLUSIONS: In this population of COPD patients, high-dose fenoterol therapy [corrected] significantly increased heart rate and cardiac output resulting in minor adverse consequences on arterial oxygenation and VA/Q relationships.

Adrenergic beta-Agonists↗
PubMed1996

Update '96 on pulmonary gas exchange pathophysiology in pneumonia.

The major determinant of abnormal pulmonary gas exchange in patients with pneumonia is characterized by marked increases in intrapulmonary shunt combined with mild to moderate ventilation-perfusion (VA/Q) inequalities. Other mechanisms influencing the levels of arterial hypoxemia, such as disequilibrium of alveolar to endcapillary oxygen diffusion or increased intrapulmonary parenchymal oxygen uptake, are trivial in the clinical arena. These pathophysiological findings mostly concur with the structural derangement of pneumonic areas. On breathing oxygen, the dispersion of pulmonary blood flow, an index sensitive to both normal and low VA/Q ratios, increases (worsens), suggesting that hypoxic pulmonary vasoconstriction is abolished, whereas intrapulmonary shunt remains unchanged. This response differs from that developed by patients with acute respiratory distress syndrome (ARDS) in whom shunt increases moderately, thereby suggesting the development of reabsorption atelectasis, but VA/Q abnormalities remain unaltered. The effects of different drugs aimed at blocking the cyclooxygenase pathway to potentially enhance the mitigated hypoxic pulmonary vasoconstriction in the consolidated lung regions have shown to be individually variable and, in general, minimally beneficial; in contrast, the recent introduction of aerosolized vasodilators may benefit patients.

Humans↗
PubMed1995

[Anatomo-pathologic lesions and gas exchange abnormalities in COPD].

Pulmonary emphysema and bronchiolar abnormalities are the most characteristic histological lesions in chronic obstructive pulmonary disease (COPD). Hypoxemia and hypercapnia are mainly due to ventilation-perfusion mismatching. Under stable clinical conditions, both intrapulmonary shunt and limitation of oxygen transport from the alveoli to the capillary do not play a critical role in the observed arterial oxygen pressure. During acute exacerbations, ventilation-perfusion inequality worsens, and some cases show mild to moderate shunting. Under these conditions extrapulmonary factors such as breathing pattern, cardiac output, and oxygen uptake have a crucial role in influencing the arterial oxygen pressure.

Humans↗
PubMed1995

Use of elastin fibre detection in the diagnosis of ventilator associated pneumonia.

BACKGROUND: Elastin fibre detection could be a simple and reliable marker of ventilator associated pneumonia. To confirm this, a prospective study was undertaken to evaluate the diagnostic yield of elastin fibre detection in the diagnosis of ventilator associated pneumonia. METHODS: Seventy eight mechanically ventilated patients were evaluated by examining endotracheal aspirates for the presence of elastin fibres. All patients were previously treated with antibiotics. Quantitative bacterial cultures of endotracheal aspirates and protected specimen brush samples were also performed. Patients were classified into three diagnostic categories: group 1, definite pneumonia (n = 25); group 2, probable pneumonia (n = 35); and group 3, controls (n = 18). RESULTS: Patients with definite and probable pneumonia were grouped together. The presence of elastin fibres in endotracheal aspirate samples was more frequent in groups 1 and 2, being found in 19 of the 60 patients compared with five of the control group. Although the presence of elastin fibres had a low sensitivity (32%), it was a reasonably specific marker (72%) of pneumonia. This specificity increased to 86% and 81% respectively when only Gram negative bacilli and Pseudomonas aeruginosa pneumonia were considered. Again, calculated sensitivity was 43% and 44% when analysing cases infected by Gram negative bacilli and Ps aeruginosa, respectively. The negative predictive value of the detection of elastin fibres in pneumonia caused by Ps aeruginosa was 81%. Detection was more frequent with infection by Gram negative bacilli (14/19), particularly with Ps aeruginosa (8/14). By contrast, pneumonia due to Gram positive cocci or non-bacterial agents uncommonly resulted in positive elastin fibre preparations (4/19, 21%). When analysing patients with and without chronic obstructive pulmonary disease, the diagnostic value of elastin fibre detection did not change. CONCLUSIONS: Potassium hydroxide preparation of elastin fibres is a rapid and simple specific marker of ventilator associated pneumonia and may be a useful technique to help diagnose pulmonary infections in mechanically ventilated patients, although this assessment is at present limited to patients without adult respiratory distress syndrome.

Adult↗
PubMed1995

Adequacy of prescribing nasal continuous positive airway pressure therapy for the sleep apnoea/hypopnoea syndrome on the basis of night time respiratory recording variables.

BACKGROUND: The increased demand of full polysomnographic studies, not only for diagnostic purposes but also for continuous positive airway pressure (CPAP) titration, has produced long waiting lists. Simpler methods are therefore needed to avoid having to refer all patients for full polysomnography. The hypothesis that CPAP therapy for the sleep apnoea/hypopnoea syndrome (SAHS) can be performed exclusively on the basis of recording night time respiratory variables was tested. METHODS: The level of CPAP in a group of 41 patients (three women) of mean (SD) age 52 (10) years, body mass index 31.5 (4.4) kg/m2, and apnoea/hypopnoea index (AHI) 53(16) events/hour was measured. During a two week period CPAP titration was performed in a random order in two settings: (1) in the sleep laboratory using full polysomnography; and (2) in the respiratory ward using equipment which continuously recorded and displayed pulse oximetry, airflow, chest and abdominal motion, and body position. The level of CPAP was increased progressively until apnoea, hypopnoea, snoring, and thoraco-abdominal paradox disappeared. RESULTS: No differences in CPAP levels (9.34(2.2) versus 9.68 (2.1) cm H2O) were found between full polysomnography and night time respiratory recordings. The accuracy of the measurement of both procedures showed good agreement. Only one patient showed a significant difference in CPAP level requirements between the two methods. CONCLUSIONS: Night time respiratory recording is sufficient to permit a reasonable choice of CPAP levels to abolish all the respiratory disturbances in most of the patients studied.

Female↗
PubMed1995

Salbutamol inhibits pulmonary effects of platelet activating factor in man.

Inhaled platelet-activating factor (PAF) provokes considerable pulmonary gas exchange disturbances in normal man and in patients with mild asthma, similar to those observed in acute severe asthma. To further examine the mechanisms involved in PAF-induced ventilation-perfusion (VA/Q) mismatch, eight healthy, non-atopic, nonsmoking subjects were studied after administration of PAF aerosol (24 micrograms). They had been previously treated with inhaled salbutamol (300 micrograms) in a randomized, double-blind, cross-over, placebo-controlled design. After placebo, PAF provoked a fall in total arterial white cell count with a rebound leukocytosis. As shown in a previous study, an overall index of VA/Q inequality (DISP R-E*, 1.64 +/- 0.10) showed a threefold increase (P < 0.006) that accounted for the increase (79%) in AaPO2 (p < 0.04) after PAF, while the respiratory system resistance (Rrs) rose by 16% (p < 0.02). In contrast, after pretreatment with salbutamol inhaled PAF had no effects on pulmonary gas exchange, Rrs, or white cell count; facial flushing and cough were also hindered. The results are consistent with the hypothesis that salbutamol inhibits PAF-induced venoconstriction in both the airway and pulmonary microcirculation.

Administration, Inhalation↗
PubMed1995

Re-intubation increases the risk of nosocomial pneumonia in patients needing mechanical ventilation.

In order to confirm that re-intubation can be a risk factor of nosocomial pneumonia in mechanically ventilated patients, a case-control study was performed. Forty consecutive patients needing re-intubation were selected as cases. Each case was paired with a matched control for the previous duration of mechanical ventilation (+/- 2 d). Nineteen (47%) of the cases developed pneumonia after re-intubation compared with 4 (10%) of the controls (odds ratio [OR] = 8.5; 95% confidence interval [CI] 1.7 to 105.9; p = 0.0007). After adjusting for age, sex, and presence of prior bronchoscopy, the conditional logistic regression analysis demonstrated that re-intubation was the only significant factor related to the development of pneumonia (OR: 5.94; 95% CI 1.27 to 22.71; p = 0.023). Sixteen (73%) of the 22 patients lying semirecumbent during the interval between extubation and re-intubation developed nosocomial pneumonia versus three (16%) of the 18 in supine position (p = 0.001). These results indicate that semirecumbency during the period between extubation and re-intubation may play a role in nosocomial pneumonia development in patients who need re-intubation. Total intensive care unit stay (19.4 +/- 10 versus 13.9 +/- 11.9 days, p = 0.0008) and crude mortality (35 versus 20%, p = 0.14) were also higher in re-intubated patients when compared with controls. We conclude that re-intubation is a risk factor for ventilator-associated pneumonia and might be avoided in a substantial number of cases.

Case-Control Studies↗
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

Time-course of stepwise CPAP titration. Behavior of respiratory and neurological variables.

Because successful medical treatment of obstructive sleep apnea/hypopnea syndrome (SAHS) depends on adequate CPAP treatment, we have analyzed in nine SAHS patients the behavior of respiratory and neurological parameters during a stepwise, polysomnography-controlled CPAP titration to achieve an optimal CPAP. Particularly, we have focused on which simple variable could predict the optimal CPAP pressure and could better define a distinctive optimal-suboptimal pattern. Main parameters analyzed through the CPAP titration procedure were respiratory events (apnea, hypopnea), the contour of inspiratory flow, the pleural pressure behavior, the thoraco-abdominal motion, oximetry, arousals, and sleep stage. During the CPAP titration we observed: (1) a rounded shape in the inspiratory flow contour was associated with the lowest esophageal pressure; (2) during stepwise increases in CPAP, almost all apnea events changed to hypopnea periods, followed by prolonged periods of limited inspiratory flow with still high esophageal pressure but without arousals (probably suboptimal CPAP); and (3) as CPAP reached suboptimal levels, sleep stage moved to deeper stages without arousals. We conclude that if during CPAP titration the end point is the disappearance of arousals, most patients with SAHS will still exhibit periods of high intrathoracic pressures with limited inspiratory flow. Alternatively, if the end point to be reached is the lowest esophageal pressure, higher CPAP levels will be needed. The contour of inspiratory flow appears as the simplest variable that best correlates with lowest esophageal pressure during CPAP titration.

Adult↗
PubMed1995

Diffuse alveolar hemorrhage in allogeneic bone marrow transplantation. A postmortem study.

To define better the syndrome of diffuse alveolar hemorrhage (DAH), we conducted a postmortem study in 77 patients who died of pulmonary complications, distributed into three groups. Group A included 47 patients with hematologic diseases treated with allogeneic bone marrow transplant (BMT); Group B, 20 patients with hematologic diseases treated with conventional chemotherapy; and Group C, 10 patients without hematologic diseases. The diagnosis of DAH was established when there was blood in at least 30% of the lung tissue evaluated without evidence of infection or any other pathologic change that could account for its presence. The presence of an associated pulmonary complication was considered only when there was normal lung parenchyma between both blood and the specific lesions. Diffuse alveolar hemorrhage was shown in 11 patients in Group A (23%) compared with 1 patient in Group B (5%) (p < 0.05). Of the 11 patients with DAH in Group A, 10 had some associated pulmonary complication: 7 presented with diffuse alveolar damage (DAD), 2 with associated bacterial pneumonia and 1 with invasive aspergillosis, 2 others had an associated cytomegalovirus (CMV) pneumonitis, and the remaining patients had an associated herpes pneumonia. There were no clinical differences between patients with and without DAH. Of 8 patients with confirmed DAH in Group A, who had been submitted to a bronchoscopic examination within 1 wk of death, 4 had normal BAL fluid; by contrast, 7 of 13 patients without DAH had hemorrhagic BAL fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Gas exchange response to intravenous aminophylline in patients with a severe exacerbation of asthma.

In patients with acute exacerbations of asthma, the intravenous administration of bronchodilators, such as salbutamol, entails the potential risk of worsening pulmonary gas exchange, despite an amelioration of airflow obstruction. The present study was designed to investigate the effect of intravenous aminophylline on pulmonary gas exchange in patients hospitalized with a severe exacerbation of asthma. We studied 12 patients (aged 41 +/- 13 yrs) admitted to the hospital because of an exacerbation of asthma. The study was of a randomized, double-blind, placebo-controlled design. Six patients were treated with intravenous aminophylline and six received placebo, in addition to standard treatment with inhaled salbutamol and intravenous corticosteroids. Forced spirometry, respiratory gas exchange, ventilation-perfusion relationships assessed with the multiple inert gas elimination technique, and systemic haemodynamics were measured at baseline and 60 min after treatment started. In the aminophylline-treated group, mean theophylline plasma levels increased to 15.2 +/- 3.6 micrograms.ml-1, forced expiratory volume (FEV1) increased by 17 +/- 12%, and forced vital capacity (FVC) by 16 +/- 10%. The mean changes in FEV1 and FVC in the aminophylline-treated group were significantly higher than in the placebo-treated group. Likewise, minute ventilation increased by 23 +/- 14% and arterial carbon dioxide tension (PaCO2) decreased by 0.4 +/- 0.3 kPa (3 +/- 2 mmHg) during aminophylline infusion. No significant changes in arterial oxygen tension (PaO2) or in ventilation-perfusion distributions were shown in aminophylline-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

Role of bronchoalveolar lavage in the diagnosis of fat embolism syndrome.

Fat embolism syndrome (FES) is a serious clinical disorder occurring in trauma patients. The diagnosis of fat embolism syndrome may be difficult to establish clinically. We therefore wanted to investigate the usefulness of bronchoalveolar lavage (BAL) in the diagnostic evaluation of fat embolism syndrome. We analysed the presence of fat droplets in BAL cells in 32 trauma patients (7 with full diagnostic criteria of fat embolism syndrome, 17 with incomplete diagnostic criteria, and 8 with no diagnostic criteria at the time of bronchoscopy), 9 nontrauma patients with acute respiratory failure and radiographic pulmonary infiltrates, and a control group composed of 10 individuals. An increased percentage of oil red O positive alveolar macrophages (cut-off point > 3%) in BAL was found in 6 out of 7 patients with definite clinical criteria of fat embolism syndrome, and in 6 out of 20 trauma patients without the clinical diagnosis of fat embolism syndrome. In two patients with fat embolism syndrome, sequential BAL showed that the percentage of positive macrophages decreased when the clinical manifestations disappeared. An increased number of BAL macrophages with fat droplets was also observed in two trauma patients without evidence of fat embolism syndrome after long-bone surgical intervention. By contrast, all non-trauma patients had a percentage of positive cells lower than 3%. Our findings suggest that BAL oil red O positive macrophages are frequently observed in trauma patients irrespective of the presence of fat embolism syndrome. Conceivably, a high number of oil red O positive macrophages could reflect clinically silent fat embolization.

Adult↗
PubMed1995

Aetiology and prognostic factors of patients with AIDS presenting life-threatening acute respiratory failure.

Respiratory failure is a significant contributor to morbidity and mortality in patients with the acquired immune deficiency syndrome (AIDS). We performed a study to investigate the aetiology, prognostic factors, and short- and long-term outcome of AIDS patients with life-threatening respiratory failure and pulmonary infiltrates. Forty-two AIDS patients (29 of whom required mechanical ventilation), admitted to a Respiratory Intensive Care Unit (ICU) from 1985 to 1992 because of severe respiratory failure (arterial oxygen tension/fractional inspiratory oxygen (Pa,O2/FI,O2) ratio at hospital admission 19 +/- 14 kPa (mean +/- SD)) and diffuse pulmonary infiltrates, were studied for evaluation of the aetiology and outcome. Necropsy studies were performed in 14 out of 23 (61%) patients who died. Pneumocystis carinii was the most common aetiology of pulmonary infiltrates (28 patients (67%)). Overall, 19 patients survived (45%) and 23 (55%) died. A multivariate analysis of prognostic factors influencing the outcome of the whole population showed that the presence of P. carinii pneumonia and the requirement for mechanical ventilation (MV) were the major determinants of outcome for this type of patient. The median survival time after ICU discharge for P. carinii pneumonia patients was lower (49 days) when compared to that of the remaining patients (154 days). Median survival time after ICU discharge for patients needing MV (112 days) did not differ from that observed in patients not requiring artificial ventilatory support (154 days). Although the ICU survival rate in this study was reasonable, 55% for the whole population, and 36% for P. carinii pneumonia patients, the poor outcome after ICU discharge, in particular for P. carinii pneumonia patients, deserves the reassessment of ICU admission criteria for this type of AIDS population.

AIDS-Related Opportunistic Infections↗
PubMed1994

Utility of selective digestive decontamination in mechanically ventilated patients.

OBJECTIVE: To assess selective digestive decontamination for preventing nosocomial pneumonia and mortality in mechanically ventilated patients. DESIGN: Prospective, randomized, placebo-controlled, double-blind study. SETTING: Respiratory intensive care unit of a 1000-bed teaching hospital. PATIENTS: 80 patients receiving mechanical ventilation for more than 72 hours. INTERVENTIONS: Patients received selective digestive decontamination using polymyxin E, tobramycin, and amphotericin B through a nasogastric tube and also topically in the oropharynx; control patients received placebo. All patients received intravenous cefotaxime for 4 days or other systemic antibiotics if required. MEASUREMENTS: Bacteriologic surveillance (three times a week) was done by quantitatively culturing tracheal aspirates, pharyngeal swabs, and gastric juice. The diagnosis of pneumonia was based on quantitative cultures of protected specimen brush samples (> or = 10(3) CFU/mL [colony forming units/mL]) or bronchoalveolar lavage fluid (> or = 10(4) CFU/mL) and autopsy findings. RESULTS: Bronchial, oropharyngeal, and gastric colonization by gram-negative bacilli and Candida species was lower in the selective digestive decontamination group compared with the placebo group. Nonsignificant differences were found in the incidence of nosocomial infections (28% compared with 37%; odds ratio, 0.66; 95% CI, 0.35 to 1.25) and nosocomial pneumonia (18% compared with 24%; odds ratio, 0.7; CI, 0.33 to 1.46) and in the crude mortality rate (31% compared with 27%; odds ratio, 1.21; CI, 0.63 to 2.34) when comparing digestive decontamination with placebo, respectively. CONCLUSIONS: Selective digestive decontamination in our mechanically ventilated patients significantly decreased the colonization rate of gram-negative bacilli and of Candida species but not of Staphylococcus aureus. It did not decrease the incidence of nosocomial pneumonia, mortality, length of stay, or the duration of mechanical ventilation.

Adult↗
PubMed1994

Gas exchange during weaning in patients with chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD), weaning from mechanical ventilation further aggravates ventilation-perfusion (VA/Q) inequalities. This is related to the development of an abnormal ventilatory pattern, characterized by rapid and shallow breathing, but also to the increase of cardiac output secondary to an abrupt increase in venous return to the lungs. These changes are not associated with further hypoxemia because of the complex interplay between intrapulmonary (i.e., VA/Q mismatch) and extrapulmonary factors (overall ventilation and cardiac output). Cardiac dysfunction together with oxygen consumption can influence arterial PO2 and alter the balance between intrapulmonary and extrapulmonary determinants of arterial blood gases resulting in further hypoxemia and causing unsuccessful weaning.

Carbon Dioxide↗