American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Mar 1997
Tris-hydroxymethyl aminomethane and sodium bicarbonate to buffer metabolic acidosis in an isolated heart model.
Metabolic acidosis induces a decrease in the developed force of cardiac muscle by affecting every step of the excitation--contraction coupling pathway. Due to transient worsening in intracellular acidosis, the value of administering sodium bicarbonate therapeutically during acute acidosis has been questioned. An alternative therapeutic drug, Tris-hydroxymethyl aminomethane (THAM) has the advantage of diffusing into the intracellular space. ⋯ The combination of THAM with sodium bicarbonate perfectly buffered acidosis without modifying PaCO2 and significantly improved contractility. The combination of THAM with sodium bicarbonate is based on the ability of THAM to capture the CO2 produced by the sodium bicarbonate buffer. This combination achieves a perfect correction of metabolic acidosis and improves myocardial performance.
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Am. J. Respir. Crit. Care Med. · Feb 1997
Intensity of training and physiologic adaptation in patients with chronic obstructive pulmonary disease.
The applicability of high-intensity training and the possibility of inducing physiologic adaptation to training are still uncertain in patients with severe chronic obstructive pulmonary disease (COPD). The purposes of this study were to evaluate the proportion of patients with moderate to severe COPD in whom high-intensity exercise training (30-min exercise session at 80% of baseline maximal power output [Wmax]) is feasible, and the response to training in these patients. We also sought to evaluate the possible influence of disease severity on the training intensity achieved and on the development of physiologic adaptation following endurance training. ⋯ Percent changes in VO2max, Wmax, and VE, were significant and of similar magnitude for both groups, whereas the decrease in arterial lactic acid for a given work rate reached statistical significance only in those patients with an FEV1 > or = 40% predicted. We conclude that although most patients were unable to achieve high-intensity training as defined in this study, significant improvement in their exercise capacity was obtained and physiologic adaptation to endurance training occurred. The training intensity expressed as a percent of the individual maximum exercise capacity, and the relative effectiveness of training, were not influenced by the severity of airflow obstruction.
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Am. J. Respir. Crit. Care Med. · Feb 1997
Comparative Study Clinical Trial Controlled Clinical TrialEffects of inhaled and oral glucocorticoids on inflammatory indices in asthma and COPD.
The role of glucocorticoids in the treatment of chronic obstructive pulmonary disease (COPD) is controversial. We have previously described high numbers of neutrophils and high concentrations of the inflammatory cytokines interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha), and of the cell activation markers eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), myeloperoxidase (MPO), and human neutrophil lipocalin (HNL) in COPD patients as compared with controls, and have postulated that the cytokines TNF-alpha and IL-8 play a role in propagating the inflammatory response in COPD. We have now studied the effects of inhaled and oral glucocorticoids on these inflammatory indices in induced sputum. ⋯ Because the lack of anti-inflammatory effect might have been due to poor drug delivery as a result of severe airflow limitation, we undertook a study examining the antiinflammatory effect of oral prednisolone (30 mg daily for 2 wk) in patients with COPD and undertook the same measurements in 10 patients with atopic asthma. Sputum eosinophil numbers, ECP, and EPO were significantly reduced in the asthmatic patients but were not modified in COPD. This confirms the clinical impression that inhaled steroids have little antiinflammatory effect, at least in the short term in this group of patients, and suggests that the inflammatory process in COPD is resistant to the antiinflammatory effect of glucocorticoids.
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Am. J. Respir. Crit. Care Med. · Feb 1997
Prone position in mechanically ventilated patients with severe acute respiratory failure.
The purpose of this study was to characterize changes in oxygenation, expressed as PaO2/F(I)O2, when patients with severe acute respiratory failure (PaO2/F(I)O2 < 150), unrelated to left ventricular failure to atelectasis, were turned to and from a supine to prone position at 1- and 4-h intervals. Ventilator settings were unchanged. Thirty-two consecutive patients were studied 1 h before, 1 and 4 h during and 1 h after placing in a prone position with PaO2/F(I)O2 of 103 +/- 28, 158 +/- 62, 159 +/- 59, and 128 +/- 52, respectively (ANOVA, p < 0.001). ⋯ In 13 of the 23 (57%) improvement persisted: 105 +/- 27, 187 +/- 58, 189 +/- 49, and 157 +/- 49, respectively (ANOVA, p < 0.001). Repeated improvements after turning to a prone position were frequently observed. Side effects in the 32 patients after a total of 294 periods in a prone position included minor skin injury and edema, two instances of apical atelectasis, one catheter removal, one catheter compression, one extubation, and one transient supraventricular tachycardia.