Iron lung versus mask ventilation in acute exacerbation of COPD: a randomised crossover study.

OBJECTIVE: To compare iron lung (ILV) versus mask ventilation (NPPV) in the treatment of COPD patients with acute on chronic respiratory failure (ACRF). DESIGN: Randomised multicentre study. SETTING: Respiratory intermediate intensive care units very skilled in ILV. PATIENTS AND METHODS: A total of 141 patients met the inclusion criteria and were assigned: 70 to ILV and 71 to NPPV. To establish the failure of the technique employed as first line major and minor criteria for endotracheal intubation (EI) were used. With major criteria EI was promptly established. With at least two minor criteria patients were shifted from one technique to the other. RESULTS: On admission, PaO(2)/FiO(2), 198 (70) and 187 (64), PaCO(2), 90.5 (14.1) and 88.7 (13.5) mmHg, and pH 7.25 (0.04) and 7.25 (0.05), were similar for ILV and NPPV groups. When used as first line, the success of ILV (87%) was significantly greater (P = 0.01) than NPPV (68%), due to the number of patients that met minor criteria for EI; after the shift of the techniques; however, the need of EI and hospital mortality was similar in both groups. The total rate of success using both techniques increased from 77.3 to 87.9% (P = 0.028). CONCLUSIONS: The sequential use of NPPV and ILV avoided EI in a large percentage of COPD patients with ACRF; ILV was more effective than NPPV on the basis of minor criteria for EI but after the crossover the need of EI on the basis of major criteria and mortality was similar in both groups of patients.

Specific immunotherapy downregulates peripheral blood CD4 and CD8 T-lymphocyte activation in grass pollen-sensitive asthma.

Several lines of evidence indicate that specific immunotherapy may act by modifying the immune responses of T-lymphocytes to the antigen. To evaluate the effect of specific immunotherapy on the activation of T-lymphocytes by cluster of differentiation cells (CD4+ and CD8+) in peripheral blood, the expression of two surface activation markers, the p55 interleukin-2 receptor (CD25) and human leucocyte antigen (HLA)-DR, was studied prospectively on circulating CD4+ and CD8+ T-cell subsets in subjects with grass-pollen sensitive asthma before and after 1 yr of treatment with specific immunotherapy. Twenty five asthmatic patients with pollen sensitivity other than grass, studied out of their pollen season, served as the control group. Specific immunotherapy improved clinical indices of disease activity including symptom scores and medication use during the pollen season of the treatment year. It had a marked effect in reducing the expression of the two activation markers, CD25 and HLA-DR, in both CD4+ (p=0.002 and p=0.005, respectively) and CD8+ (p=0.01 and p=0.01, respectively) T-cell subsets, in parallel with a significant decrease in CD23 expression on B-cells (p=0.008) and in grass-specific immunoglobulin E levels (p=0.01) in the peripheral blood of subjects with grass pollen-sensitive asthma. The decreased T-lymphocyte activation observed in immunotherapy-treated subjects after the treatment year was significant (p=0.05) in comparison with the control group. These data add to the view that the efficacy of specific immunotherapy may be attributed to the downregulation of T-cell responses.

Lymphocyte activation markers in peripheral blood before and after natural exposure to allergen in asthmatic patients.

Activated T cells and their cytokine products are involved in the pathogenesis of asthma. However, little is known about changes in circulating T cell subsets in allergic asthma during natural exposure to allergens. We examined whether natural allergen exposure of patients with atopic asthma is associated, in vivo, with changes of lymphocyte subtypes and activation markers in peripheral blood. Ten patients with atopic mild asthma sensitized only to grass pollen had peripheral venous blood lymphocyte analyses before and during the pollen season. No significant changes were observed. There was an inversion in the CD4/CD8 ratio in the peripheral blood both before (p < 0.05) and during (p < 0.01) seasonal exposure when compared to a group of healthy, age-matched control subjects. Evaluation of T cells expressing CD25 activation marker also demonstrated a significant reduction of CD4+25+ cells and a significant increase of CD+25+ cells compared to the controls. CD23+ cells (B lymphocytes with low affinity Fc IgE receptor) in the asthmatic group out of the pollen season correlated negatively with hyperreactivity to methacholine (p < 0.05). We conclude that in mild allergic asthmatic patients sensitized to grass pollen, blood lymphocyte subsets and their activation markers do not reflect seasonal exposure. Moreover, our findings show that these patients have higher proportions of CD8+ cells expressing higher levels of CD25 in their blood compared to normal subjects both before and during the pollen season.

Muscle and serum magnesium in pulmonary intensive care unit patients.

Muscle specimens by means of quadriceps femoris needle biopsy and blood samples were obtained in 32 patients consecutively admitted to a pulmonary ICU for chronic obstructive pulmonary disease and acute respiratory failure, and in 30 age and sex-matched healthy control subjects. Muscle magnesium (Mg) and potassium (K) content was assessed by atomic absorption spectrophotometry; serum electrolytes were also measured. The presence of clinical and biochemical correlates of low serum and muscle Mg was investigated. Three (9.4%) out of 32 patients had hypomagnesemia (Mgs less than or equal to 0.7 mmol/L) with normal muscle Mg values, whereas low muscle Mg values were found in 15 (47%) of 32 patients, with no alterations of serum Mg levels. Muscle Mg was decreased significantly in pulmonary ICU patients as compared to control subjects. No significant correlation was present between serum and muscle Mg, or between serum and muscle K. Significant relationships between muscle Mg and both muscle and intracellular K concentrations were also found. Lower values for muscle and intracellular K and a higher incidence of both more prolonged ICU stays and ventricular extrasystolic beats characterized the ICU patients with altered muscle Mg levels. We conclude that, given the serious complications of Mg metabolism derangements, the presence of altered cell Mg content should be taken into account in pulmonary ICU patients. Moreover, in these patients, serum Mg levels are of little value in the diagnosis of intracellular Mg deficits.