Biomedical subjects

R Rodriguez-Roisin

Publications and source records attributed to R Rodriguez-Roisin.

At least 145 records · Page 8Linked to original sources

PubMed1990

Bronchial reactivity in patients with chronic renal failure undergoing haemodialysis.

We hypothesized that patients with chronic renal failure may present nonspecific bronchial hyperreactivity due to subclinical interstitial lung oedema. To assess lung function disturbances and methacholine (MTH) bronchial responsiveness in this condition, we studied 12 patients (9 men and 3 women; 41.8 +/- 13.3 yrs (SD] with chronic renal failure undergoing regular haemodialysis (HD). Before HD, mean results of conventional lung function tests were within the normal range: forced expiratory volume in one second (FEV1), 89 +/- 12.9% predicted; forced mid-expiratory flow (FEF25-75), 81 +/- 36.7% predicted; total lung capacity (TLC), 94 +/- 14.6% predicted, but 3 subjects presented mild reduction in lung volumes and 5 individuals showed mild obstructive ventilatory impairment. After HD, maximal expiratory flow rates increased significantly (FEV1, + 8.2 +/- 5.1% (p less than 0.005); FEF25-75, +26.2 +/- 25.9% (p less than 0.005]. Interestingly, these increases in FEV1 after HD correlated with body weight loss during HD (r = 0.74, p less than 0.01). In contrast, pre-HD bronchial reactivity was within the normal range (mean % change in FEV1 after MTH, -3.7 +/- 4.5%; range, +1- -14%) without significant changes in methacholine bronchial responsiveness after HD. We speculate that interstitial lung oedema may play a significant role in lung function impairment observed in patients with chronic renal failure. This study shows that nonspecific bronchial hyperreactivity is not present in clinically stable patients with this disorder.

Adult↗

PubMed1990

Characteristics of patients with soybean dust-induced acute severe asthma requiring mechanical ventilation.

Patients presenting with acute severe asthma during the Barcelona's outbreaks caused by soybean dust inhalation from August, 1981, through September, 1987, characteristically showed an abrupt severe onset of each attack followed by a rapid relief of symptoms after treatment. To throw further light on clinical findings, pathophysiology and outcome in the most life-threatening episodes, we reviewed records of acute severe asthma patients treated by mechanical ventilation in one of the four main hospitals of the city. Twelve such patients (15 episodes) were compared to 24 non-epidemic asthmatic patients (25 episodes) also treated by mechanical ventilation in the same institution during the same period of time. There was a male predominance during outbreaks (p less than 0.03) and epidemic patients were ventilated fewer hours (12 +/- 8 h) (mean +/- SD), admitted fewer days to intensive care (1.6 +/- 0.7 days), and hospitalized fewer days (7.1 +/- 4.4 days) than non-epidemic patients (65 +/- 84 h, 4.6 +/- 3.8 days (p less than 0.001, each), and 16.0 +/- 13.2 days (p less than 0.004), respectively). These differences together with both the fulminant presentation of the episodes of epidemic asthma and the point-source origin of the asthma outbreaks previously shown are consistent with the unusual nature of the aetiologic agent, soybean dust.

Acute Disease↗

PubMed1989

Community outbreaks of asthma associated with inhalation of soybean dust. Toxicoepidemiological Committee.

Since 1981, 26 outbreaks of asthma have been detected in the city of Barcelona. The geographic clustering of cases close to the harbor led us to consider the harbor as the probable source of the outbreaks. We therefore studied the association between the unloading of 26 products from ships in the harbor and outbreaks of asthma in 1985 and 1986. All 13 asthma-epidemic days in these two years coincided with the unloading of soybeans (lower 95 percent confidence limit of the risk ratio, 7.2). Of the remaining 25 products, only the unloading of wheat was related to the epidemics of asthma, although when adjusted for the unloading of soybeans the relation was not statistically significant. High-pressure areas and mild southeasterly to southwesterly winds, which favored the movement of air from the harbor to the city, were registered on all epidemic days. Particles of starch and episperm cells that were recovered from air samplers placed in the city had morphologic characteristics identical to those of soybean particles. Furthermore, the lack of bag filters at the top of one of the harbor silos into which soybeans were unloaded allowed the release of soybean dust into the air. We conclude that these outbreaks of asthma in Barcelona were caused by the inhalation of soybean dust released during the unloading of soybeans at the city harbor.

Asthma↗

PubMed1989

New design for fixation of surgically obtained lung specimens.

A new design for lung fixation at a constant transpulmonary pressure is described. The head pressure of the apparatus can easily be set in a range from 15 to 95 cm H2O and maintained at a constant level through the recirculation of the fixative fluid. Moreover, the dimensions of the device are smaller than those previously reported. To analyze the efficiency of the equipment the estimated total post-fixing lung volume (TLV) in 12 surgically obtained lung specimens was calculated and compared with helium single-breath total lung capacity measurements (TLCsb). The TLV/TLCsb ratio was 102 +/- 5%. In addition, TLV was related to predicted TLC values (TLCpred) from different reference equations. The TLV/TLCpred ratios ranged from 89 to 99%. Estimated volumes of formalin fixed lungs did not show significant differences to those obtained by TLCsb measurements (p = 0.49). Consequently, it can be concluded that the fixation procedure performed with this device does not produce changes in air space dimensions of surgically obtained lung specimens. Moreover, the variability in TLV/TLC ratios depends upon either the technique of TLC measurement or the set of predicted values used.

Adult↗

PubMed1989

Ventilation-perfusion mismatching in acute severe asthma: effects of salbutamol and 100% oxygen.

Ventilation-perfusion (VA/Q) relationships and gas exchange were studied by the multiple inert gas technique in 19 patients admitted to hospital with acute severe asthma (FEV1 41% predicted) before and during the administration of intravenous salbutamol, inhaled salbutamol, or 100% oxygen. Eight patients received a continuous intravenous infusion of salbutamol (4 micrograms/min, total dose 360 micrograms) and were studied before treatment, after 60 and 90 minutes of treatment, and one hour after treatment had been discontinued. Six patients had measurements before and 15 minutes after inhaling 300 micrograms salbutamol from a metered dose inhaler on two occasions (total dose 600 micrograms) and one hour after the last dose. Measurements were also made in five patients before and while they breathed 100% oxygen for 20 minutes. At baseline (fractional inspired oxygen (FiO2) 21%) all patients showed a broad unimodal (n = 10) or bimodal (n = 9) distribution of blood flow with respect to VA/Q. A mean of 10.5% of the blood flow was associated with low VA/Q units without any appreciable shunt. One of the best descriptors of VA/Q inequality, the second moment of the perfusion distribution on a log scale (log SD Q), was moderately high with a mean of 1.18 (SEM 0.08) (normal less than 0.6). Measures of VA/Q inequality correlated poorly with spirometric findings. After salbutamol the increase in airflow rates was similar regardless of the route of administration. Intravenous salbutamol, however, caused a significant increase in heart rate, cardiac output, and oxygen consumption (VO2); in addition, both perfusion to low VA/Q areas and log SD Q increased significantly. Inhaled salbutamol caused only minor changes in heart rate, cardiac output, VO2, and VA/Q inequality. Arterial oxygen tension (PaO2) remained unchanged during salbutamol administration, irrespective of the route of administration. During 100% oxygen breathing there was a significant increase in log SD Q (from 1.11 to 1.44). It is concluded that patients with acute severe asthma show considerable VA/Q inequality with a high level of pulmonary vascular reactivity. Despite similar bronchodilator effects from inhaled and intravenous salbutamol, VA/Q relationships worsened only during intravenous infusion. PaO2 remained unchanged, however, because the change in VA/Q relationships was associated with an increase in metabolic rate and cardiac output.

Acute Disease↗

PubMed1989

Therapeutic efficacy of the combination of aztreonam with cefotaxime in the treatment of severe nosocomial pneumonia. Comparative study against amikacin combined with cefotaxime.

The combination aztreonam + cefotaxime (AZ + CE) was compared to amikacin + cefotaxime (AM + CE) in the treatment of nosocomial pneumonia acquired at the intensive-care unit. This study included a total of 33 patients fulfilling criteria for nosocomial pneumonia. 16 of them were randomly allocated to the AZ + CE group and 17 to the AM + CE group. The empirical treatment was effective for 78% of AZ + CE cases and 92% of AM + CE cases (p = NS). Clinical care was observed in 77% of cases (10 out of 13 evaluable) in the AZ group and in 75% of the group treated with AM (12 cases out of 16 evaluable; p = NS). In the evaluable cases, treatment failure was associated with injections due to the following organisms: Acinetobacter calcoaceticus (1) and Pseudomonas aeruginosa (1) in the AZ group and A. calcoaceticus (1) in the AM group. Superinfections were observed only in the AM group P. aeruginosa. A. calcoaceticus, Streptococcus viridans, Candida albicans, Aspergillus fumigatus and Serratia marcescens. Both the peak and through serum concentrations of AZ and AM were maintained within normal ranges. Finally, an impairment of renal tubular function was observed in the group of patients treated with AM, as measured by urinary levels of N-acetyl-beta-D-glucosaminidase and leucine aminopeptidase sequentially during the treatment. These changes in renal functions alterations mentioned were not observed in the AZ group. It is concluded that the AZ + CE combination is an effective empirical and active antibiotic treatment against severe nosocomial pneumonia. Aztreonam has no renal toxicity, which is an advantage to take into account in patients with altered renal function.

Adult↗

PubMed1989

Pulmonary hemodynamics and gas exchange during exercise in liver cirrhosis.

We have recently shown that ventilation-perfusion (VA/Q) mismatching at rest in cirrhosis is due to an abnormal pulmonary vascular tone. It has been suggested that in patients with cirrhosis, O2 transfer might become diffusion-limited during exercise. This study examined pulmonary hemodynamics and mechanisms modulating gas exchange during exercise (60 to 70% VO2max) in six patients (41 +/- 5 yr, mean +/- SEM) with cirrhosis but with normal lung function tests. At rest, QT was high (8.4 +/- 0.5 L/min), pulmonary vascular resistance (PVR) was low (0.61 +/- 0.17 mm Hg/L/min), and there was mild to moderate VA/Q mismatching (LogSD Q, 0.79 +/- 0.09; normal range, 0.3 to 0.6). However, hyperventilation (PaCO2, 29 +/- 2 mm Hg) and high QT (thus, high PVO2, 41 +/- 2 mm Hg) contributed to the maintenance of PaO2 within normal values (99 +/- 7 mm Hg). Exercise VO2 (1,278 +/- 122 ml/min) was normal relative to work load, but, contrary to that in normal subjects, QT was higher and PVR did not fall. During exercise, PaO2 showed a trend to decrease (to 90 +/- 5 mm Hg) and PaCO2 to rise (to 35 +/- 2 mm Hg), but the differences failed to reach statistical significance (p = 0.07 each). PVO2 fell significantly with exercise (41 +/- 2 to 33 +/- 0.3 mm Hg, p less than 0.05), but neither AaPO2 (15 +/- 7 to 21 +/- 6 mm Hg) nor VA/Q inequality (LogSD Q, 0.82 +/- 0.11) changed. No systemic difference was noticed between predicted and measured PaO2 values, suggesting no O2 diffusion impairment during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Mechanisms of hypoxemia in patients with status asthmaticus requiring mechanical ventilation.

Eight consecutive patients (mean +/- SD age, 43 +/- 11 yr) with acute severe asthma (status asthmaticus) requiring assisted ventilation were studied within the first 24 to 48 h of admission, at maintenance FIO2 and while breathing 100% O2, using the multiple inert gas elimination technique. Ventilation-perfusion (VA/Q) inequality was characterized by a marked bimodal blood flow distribution (perfusion to normal and low VA/Q populations) in all but two patients, with a mean of 27.6 +/- 12.3% of the total perfusion present in the low VA/Q ratio units (between 0.1 and 0.005). As a result, the dispersion of pulmonary blood flow distribution (log SDQ) was severely abnormal (mean, 1.65 +/- 0.28; normal range, 0.3 to 0.6). No patient had a substantial shunt (VA/Q = 0) (mean value, 1.5 +/- 2.3%). The ventilation distribution was never bimodal, but the dispersion of the ventilation distribution (log SDV) was moderately elevated (1.01 +/- 0.24). High VA/Q areas (ventilation to VA/Q units between 10 and 100) were generally absent. While breathing 100% O2, PaO2, PvO2, and PaCO2 significantly rose, as did shunt and blood flow dispersion. Patients with life-threatening acute severe asthma treated by mechanical ventilation show: (1) the most abnormal gas exchange characteristics of the VA/Q spectrum observed to date in human asthma but essentially the same pattern as in patients with less severe disease; (2) a high level of hypoxic pulmonary vascular response; (3) a significant amount of shunt while breathing 100% O2, suggesting the presence of absorption atelectasis or redistribution of blood flow.

Adult↗

PubMed1989

Ventilation-perfusion mismatching in chronic obstructive pulmonary disease during ventilator weaning.

Using the multiple inert gas elimination technique, we studied ventilation-perfusion (VA/Q) relationships in eight patients with chronic obstructive pulmonary disease (COPD) during mechanical ventilation (MV) and again during weaning (spontaneous ventilation [SV] through an endotracheal tube) from MV needed for acute respiratory failure. The patients, seven men and one woman with a mean age of 63 +/- 2.8 (SEM) yr (FEV1 33 +/- 5.2% of predicted), required MV for 9.0 +/- 2.4 days prior to the study. The patients were studied at maintenance FIO2 (0.28 to 0.40) while breathing 100% O2, both during MV and SV. After 30 min of SV, PaCO2 increased from 48.9 +/- 3.4 to 58.3 +/- 3.1 mm Hg (p = 0.003) and pH decreased from 7.42 +/- 0.01 to 7.36 +/- 0.01 (p = 0.001) without significant changes in PaO2. Despite a decrease in tidal volume (VT) from 700.0 +/- 41.1 during MV to 313.0 +/- 39.6 ml during SV (p = 0.001), minute ventilation remained unchanged (from 8.2 +/- 0.7 during MV to 7.4 +/- 0.6 L/min during SV). Furthermore, cardiac output (QT), oxygen delivery (QO2), and mixed venous PO2 (PVO2) significantly rose during SV when compared with the MV (QT: from 4.7 +/- 0.4 to 6.7 +/- 0.7 L/min, p = 0.011; QO2: from 857.3 +/- 113.0 to 1078.5 +/- 158.9 ml/min, p = 0.0074; PVO2: from 36.7 +/- 1.1 to 42.3 +/- 2.2 mm Hg, p = 0.041). Overall VA/Q inequality worsened as blood flow was redistributed to low VA/Q areas (from 9.4 +/- 4.4 to 19.6 +/- 5.3% of QT, p = 0.05). The dispersion of the ventilation distribution (log SDV) significantly worsened during SV (from 1.0 +/- 0.08 during MV to 1.2 +/- 0.08 during SV, p = 0.044). No changes were observed in either series dead space or ventilation of high VA/Q ratio units.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1988

Serial relationships between ventilation-perfusion inequality and spirometry in acute severe asthma requiring hospitalization.

Patterns of VA/Q distribution and their relationship to spirometric indices were studied in 10 patients with acute severe asthma requiring hospitalization (7 women and 3 men 41.0 +/- 5.6 yr of age, mean +/- SEM) on admission and during subsequent recovery. On admission, all patients received the standard therapeutic regimen for our hospital. Spirometry and essentially noninvasive multiple inert gas elimination measurements were obtained serially, approximately once every day, whereas conventional arterial blood gases were determined every 3 days. On admission, all patients showed severe air-flow obstruction (FEV1/FVC% = 34.1 +/- 4.3%) and moderate to severe hypoxemia without CO2 retention (PaO2 = 50.5 +/- 2.6 mm Hg; PaCO2 = 37.1 +/- 2.4 mm Hg; AaPO2 = 53.7 +/- 3.0 mm Hg). Nine of the 10 patients showed bimodal blood flow distributions (dispersion of blood flow distribution, log SD Q = 1.34 +/- 0.11; normal range, 0.3 to 0.6) with only small amounts of shunt (1.09 +/- 0.8%). However, no significant interindividual correlations were observed between maximal expiratory flow rates (FEV1 and FEF25(-75) and log SD Q (r2 = 0.14 and 0.006, respectively). This lack of correlation persisted throughout hospitalization. Despite both clinical and spirometric improvement in all patients, there was simultaneous improvement in VA/Q matching in only one patient. Statistically significant negative correlations between maximal expiratory flow rates and gas exchange did develop toward the end of the study (Weeks 3 and 4 after discharge) when maximal recovery of physiologic changes associated with the acute asthma attack was achieved.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1988

Effect of almitrine on ventilation-perfusion distribution in adult respiratory distress syndrome.

Almitrine improves ventilation/perfusion relationships (VA/Q) in COPD, but its effects in ARDS, in which VA/Q mismatching is the cause of severe hypoxemia, are not known. The effects of almitrine on pulmonary gas exchange and circulation were assessed in 9 patients with ARDS who were sedated, paralyzed, and mechanically ventilated at constant FlO2 (range, 0.48 to 0.74). Systemic and pulmonary hemodynamics, conventional gas exchange, and the VA/Q distribution by the multiple inert gas elimination technique (MIGT) were measured before (baseline), during (ALM 15), at the end of (ALM 30), and at 30-min intervals after (POSTALM 30, 60, and 90) the intravenous infusion of 0.5 mg/kg body weight of almitrine over 30 min. Almitrine significantly increased PaO2 from 78 +/- 15 mm Hg to 140 +/- 49 at ALM 15 and 138 +/- 52 at ALM 30. AaPO2 and QS/QT decreased during the administration of the drug. The MIGT showed that almitrine redistributed pulmonary blood flow from shunt areas (reduction from 29 +/- 11 to 17 +/- 11% of QT) to lung units with normal VA/Q ratios (increase from 63 +/- 9 to 73 +/- 6% of QT). The Ppa increased from 26 +/- 5 to 30 +/- 5 mm Hg without changes in QT. Changes were transient, returning toward baseline 30 min after stopping the infusion of the drug. Almitrine significantly reduced the VA/Q inequalities present in ARDS and may be useful in the management of those patients.

Adult↗

PubMed1988

Diagnostic value of telescoping plugged catheters in mechanically ventilated patients with bacterial pneumonia using the Metras catheter.

A new guiding technique, Metras catheter (MC), for blindly introducing a telescoping plugged catheter (TPC) was applied to 25 mechanically ventilated patients with suspected bacterial pneumonia (BPN). Results obtained with TPC-MC were compared with those obtained with TPC using a conventional fiberoptic bronchoscope (FB) in random order. The diagnosis of BPN was definitely confirmed in 18 patients. In 7 patients, all TPC samples (MC and FB) were sterile, and a diagnosis other than BPN was proved. In the former group, colony-forming units equal to or greater than 10(3)/ml of one or more microorganisms were obtained in 61% of TPC-MC and in 66% of TPC-FB samples. These percentages increased to 64 and 71%, respectively, when 4 patients with previous antibiotic treatment were excluded from the study group. Agreement was observed between microorganisms cultured from both TPC samples in 11 of 18 patients with proved BPN (61%). Complete disparity was seen only in 2 patients (11%). Two patients developed a self-limiting hemoptysis after the TPC procedure (MC and FB, respectively). We conclude that TPC-MC is both a sensitive and specific technique for the diagnosis of BPN in mechanically ventilated patients. Because the diagnostic value of TPC-MC is similar to that of TPC-FB, we propose that the MC be used in patients receiving mechanical ventilation when the FB is not available. The simplicity and lower cost of this new system are important advantages to be considered over the fiberoptic bronchoscope.

Adult↗

PubMed1988

Different patterns of gas exchange response to exercise in asbestosis and idiopathic pulmonary fibrosis.

To analyse the pattern of pulmonary gas exchange during maximal exercise (Emax) in asbestosis, we compared nine subjects with this disease (1 female/8 male), aged 54 +/- 11 yrs (mean +/- SD), to nine patients (1 female/8 male) with idiopathic pulmonary fibrosis (IPF) of a similar age, height, weight and smoking history, both at rest and during Emax. No differences were observed in dynamic and static lung volumes between the groups. However, patients with IPF had a lower DLCOsb and KCO (p less than 0.005 and 0.05, respectively). At rest, both groups showed mild arterial hypoxaemia (76 +/- 11, asbestosis, vs 77 +/- 11 mmHg, IPF), widened AaPO2 (32 +/- 14 vs 31 +/- 13 mmHg) and slight increases in VD/VT (47 +/- 12 vs 46 +/- 11%), respectively. During Emax, PaO2 fell to 51 +/- 7 mmHg in patients with IPF whereas those with asbestosis had PaO2 of 73 +/- 21 mmHg (p less than 0.05). Conversely, those with asbestosis were able to reduce VD/VT (from 47 +/- 12 to 39 +/- 10%, p = 0.01) as opposed to those with IPF (from 46 +/- 11 to 47 +/- 13%). Furthermore, DLCOsb and AaPO2 during Emax were highly correlated only in IPF (r: -0.84, p less than 0.01). Despite the finding that both diseases represent a diffuse pulmonary fibrosis with a similar degree of resting ventilatory impairment, the pattern of gas exchange during exercise is different in each. These differences may be related to the underlying morphology of each process, which probably includes more airway disease and less pulmonary vascular involvement and/or a different degree of interstitial fibrotic change in asbestosis.

Asbestosis↗

PubMed1988

Lung function changes following Legionnaires' disease.

Eleven out of thirteen patients hospitalized because of severe pneumonia caused by Legionella Pneumophila were evaluated over a period of 53 months. During the acute phase, all but one patient manifested severe hypoxaemia, needing either supplementary oxygen or, in the case of three, mechanical ventilation and one died. Following recovery, two patients complained of mild shortness of breath alone. However, most of the individuals showed subclinical mild to moderate ventilatory and/or gas exchange abnormalities a few months after discharge (less than 6 months). Despite the fact that some of these functional findings in part persisted at long-term (6-33 months), a significant overall improvement in lung function was noticed. The main pulmonary functional sequelae following Legionnaires' Disease might include a restrictive ventilatory defect, a low transfer factor and hypoxaemia.

Acute Disease↗

PubMed1987

Bronchoalveolar lavage cellular analysis and gallium lung scan in the assessment of patients with amiodarone-induced pneumonitis.

Seven patients suffering from amiodarone-induced pneumonitis were followed after diagnosis over a period of 16 +/- 6 months. All of them showed clinical, radiographic and functional manifestations of interstitial lung disease. Bronchoalveolar lavage was performed on 6 of them and disclosed lymphocytosis in 2 cases (associated to eosinophilia in 1 of them), neutrophilia in 1 and normal differential count in 2. In 1 case there were abundant hemosiderin-laden macrophages. In addition, all patients evidenced an increased 67Ga lung scan uptake. After discontinuation of amiodarone therapy (with or without corticosteroid therapy), 67Ga lung uptake normalized in 3 cases, but remained increased in 3. Bronchoalveolar lavage was repeated only in 2 cases, showing disappearance of lymphocytosis in one and abundant hemosiderin-laden macrophages in the other. Our results suggest that (1) hemosiderin-laden macrophages can be found in bronchoalveolar lavage in patients with amiodarone-induced pneumonitis, probably related to subclinical chronic left-sided heart failure; (2) 67Ga lung scan appears to be a sensitive marker of amiodarone pneumonitis, although it can remain abnormal after pulmonary clinical, radiographic and functional normalization.

Adult↗

PubMed1987

Gas exchange and pulmonary vascular reactivity in patients with liver cirrhosis.

To investigate the mechanisms underlying abnormal gas exchange in liver cirrhosis, 15 patients were studied while breathing room air, 11% O2, and 100% O2 in random sequence. Under basal conditions, patients showed mild reductions from normal in systemic and pulmonary vascular resistance, normal PaO2 (mean, 92.5 +/- 2.5 mm Hg), mild hypocapnia (mean, 34 +/- 0.7 mm Hg), and a slightly right-shifted oxyhemoglobin dissociation curve (P50, 27.2 +/- 0.4 mm Hg; 2,3-DPG, 13.1 +/- 0.6 mumol/g). Using the multiple insert gas elimination technique, we found mild to moderate ventilation-perfusion (VA/Q) inequality with a mean of 5% (range, 0 to 20%) of cardiac output (QT) perfusing low VA/Q ratio (less than 0.1) areas but no shunt. Breathing 11% O2, there were significant increases in QT, pulmonary artery pressure, and vascular resistance, whereas no changes occurred in VA/Q distribution, and there was no evidence for alveolar-endcapillary diffusion limitation for O2. In contrast, after 100% O2 shunt developed and VA/Q relationships worsened without significant hemodynamic changes. Furthermore, patients with cutaneous spider nevi (n = 8) showed more hepatocellular dysfunction (lower prothrombin values), lower systemic and pulmonary vascular resistance, less hypoxic pulmonary vasoconstriction (HPV), lower PaO2, and more VA/Q mismatch than did those without spiders. Our results confirm, therefore, that HPV is not fully abolished, as previously described, in hepatic cirrhosis. However, those patients with more advanced hepatic disease exhibit inadequate pulmonary vascular tone, which increases VA/Q inequality and lowers PaO2.

Adult↗

PubMed1986

Oxyhemoglobin affinity in patients with chronic obstructive pulmonary disease and acute respiratory failure: role of mechanical ventilation.

Oxyhemoglobin affinity was assessed in 20 subjects with chronic obstructive pulmonary disease, all of whom experienced acute respiratory failure. PaCO2, pH, and 2,3-diphosphoglycerate (2,3-DPG) were measured 24 and 48 h after admission, and then during weaning (for the ten patients on mechanical ventilation) or on discharge (for the ten nonventilated patients). At 24 h, nonventilated patients had a lower pH (p less than .001) and 2,3-DPG concentration (p less than .05) and a higher PaCO2 (p less than .01) than ventilated patients; 48 h later only PaCO2 was higher (p less than .01) in the former, and there were no differences between the two groups in the final set of measurements. There was a persistent left shift in the oxyhemoglobin dissociation curve (P50 at pH 7.4) in both groups throughout the study period. In contrast, the in vivo P50 was significantly lower in ventilated patients only at 24 h (22.7 +/- 2.2 vs. 25.8 +/- 1.5 torr, respectively, p less than .005). Our results suggest that changes of in vivo P50 in ventilated patients are probably related to the Bohr effect induced by mechanical ventilation. The latter swiftly corrects severe respiratory acidosis, causing an intra-erythrocytic alkalotic pH and raising the levels of 2,3-DPG.

2,3-Diphosphoglycerate↗

PubMed1986

Effect of nifedipine on arterial hypoxaemia occurring after methacholine challenge in asthma.

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) kPa)) was significantly greater than after placebo (11.7 (2.4) mm Hg; (1.56 (0.32) kPa) p less than 0.03). Our data show that although oral nifedipine significantly reduces airway reactivity in patients with mild bronchial asthma, it also adversely affects pulmonary gas exchange, resulting in a lowered postchallenge Pao2, probably because of worsening ventilation-perfusion relationships.

Adult↗