An anecdote is an anecdote is an anecdote ... but a clinical trial is data

Should androgenic anabolic steroids be considered in the treatment regime of selected chronic obstructive pulmonary disease patients?

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) is a widespread disease with high morbidity rates. Advanced stages can be complicated by unintentional weight loss and muscle wasting, which may contribute to increased morbidity and mortality. Reversal of weight loss increases muscle strength and exercise capacity and improves survival. This can partly be achieved by nutritional support, preferably combined with increase in exercise. Androgenic anabolic steroids (AASs), of which testosterone is the parent hormone, increase muscle size and strength. Due to these anabolic effects, AASs may emerge as a treatment option in COPD patients suffering from muscle wasting.

RECENT FINDINGS

Seven trials investigated the effects of AAS in patients with COPD. Some studies also included nutritional therapy and/or a pulmonary rehabilitation program. Compared with placebo, AASs increase lean body mass (LBM) and muscle size. However, no consistent effects on muscle strength, exercise capacity, or pulmonary function are seen.

SUMMARY

AASs increase LBM in patients with advanced stages of COPD. No consistent beneficial effect on other endpoints was demonstrated in the reviewed trials. However, probably higher doses of AASs are needed to exert a clinically meaningful effect on muscle strength or exercise capacity. Currently, no evidence is available to recommend AASs to all patients with COPD. In individual cases, treatment with AASs can be considered, particularly in men with advanced COPD, moderate-to-severe functional impairment, muscle wasting and on chronic corticosteroid therapy. Treatment with AASs should preferably be combined with a rehabilitation program and nutritional support. AASs should not be used in women or in men with symptomatic heart disease. When treatment with AASs is considered, intramuscular nandrolone-decanoate is preferred in a dose of 50-200 mg per week for a period of 12 weeks. However, the efficacy of AAS treatment in COPD patients needs further clarification in well designed, adequately powered clinical studies.

Extracorporeal membrane oxygenation: a ten-year experience

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a supportive therapy used for severe acute respiratory distress syndrome (ARDS). We present outcome, clinical parameters, and complications in a cohort of 245 ARDS patients of whom 62 were treated with ECMO.

METHODS

Data of all ARDS patients were prospectively collected between 1991 and 1999. Outcome and clinical parameters of patients treated with and without ECMO were evaluated.

RESULTS

One hundred thirty-eight patients were referred from other hospitals, 107 were primarily located in our hospital. About one fourth of these patients were treated with ECMO. The survival rate was 55% in ECMO patients and 61% in non-ECMO patients.

CONCLUSIONS

ECMO is a therapeutic option for patients with severe ARDS, likely to increase survival. However, a randomized controlled study proving its benefit is still awaited. Until the development of a causal or otherwise superior therapy ECMO should be used in selected patients.

Nutrition in chronic obstructive pulmonary disease

Weight loss is a frequently occurring complication in patients with chronic obstructive pulmonary disease (COPD) and is a determining factor of functional capacity, health status, and mortality. Weight loss in COPD is a consequence of increased energy requirements unbalanced by dietary intake. Both metabolic and mechanical inefficiency contribute to the elevated energy expenditure. A disbalance between protein synthesis and protein breakdown may cause a disproportionate depletion of fat-free mass in some patients. Nutritional support is indicated for depleted patients with COPD because it provides not only supportive care, but direct intervention through improvement in respiratory and peripheral skeletal muscle function and in exercise performance. A combination of oral nutritional supplements and exercise or anabolic stimulus appears to be the best treatment approach to obtaining significant functional improvement. Patients responding to this treatment even demonstrated a decreased mortality. Poor response was related to the effects of systemic inflammation on dietary intake and catabolism. The effectiveness of anticatabolic modulation requires further investigation.

Elastin fibers and the diagnosis of bacterial pneumonia in the adult respiratory distress syndrome

OBJECTIVE

It has been inferred from previous work that 40% potassium hydroxide preparations of lower respiratory tract secretions that demonstrate elastin fibers have a 100% specificity and positive predictive value in diagnosing bacterial pneumonia in intubated, mechanically ventilated patients without the adult respiratory distress syndrome (ARDS). Our aim was to assess the specificity of 40% potassium hydroxide preparations in diagnosing bacterial pneumonia in patients with ARDS and suspected pneumonia.

DESIGN

Prospective, case-referral clinical study.

SETTING

Referral hospital.

PATIENTS

Of 24 patients with ARDS who were intubated and mechanically ventilated with suspected bacterial pneumonia, 22 were assessable and evaluated for this report.

INTERVENTIONS

Tracheo-bronchial aspirates were obtained from all patients and analyzed for elastin fibers using 40% potassium hydroxide.

MEASUREMENTS AND MAIN RESULTS

Of the 22 assessable patients, ten patients did not have a complicating bacterial pneumonia. Six of these ten patients had potassium hydroxide preparations that demonstrated elastin fibers (false positives). The other four patients had preparations that did not demonstrate elastin fibers (true negatives). Specificity was 40%.

CONCLUSION

Elastin fiber preparations are not specific for diagnosing bacterial pneumonia in patients with ARDS.

Voltage-gated K+ currents regulate resting membrane potential and [Ca2+]i in pulmonary arterial myocytes

The membrane potential (Em) of pulmonary arterial smooth muscle cells (PASMCs) regulates pulmonary arterial tone by controlling voltage-gated Ca2+ channel activity, which is a major contributor to [Ca2+]i. The resting membrane is mainly permeable to K+; thus, the resting Em is controlled by K+ permeability through sarcolemmal K+ channels. At least three K+ currents, voltage-gated K+ (KV) currents, Ca(2+)-activated K+ (KCa) currents, and ATP-sensitive (KATP) currents, have been identified in PASMCs. In this study, both patch-clamp and quantitative fluorescent microscopy techniques were used to determine which kind(s) of K+ channels (KV, KCa, and/or KATP) is responsible for controlling Em and [Ca2+]i under resting conditions in rat PASMCs. When the bath solution contained 1.8 mmol/L Ca2+ and the pipette solution included 0.1 mmol/L EGTA, depolarizations (-40 to +80 mV) elicited both KCa and KV currents. Removal of extracellular Ca2+ and increase of intracellular EGTA concentration (to 10 mmol/L) eliminated the Ca2+ influx-dependent KCa current. 4-Aminopyridine (4-AP, 5 to 10 mmol/L) but not charybdotoxin (ChTX, 10 to 20 nmol/L) significantly reduced KV current under these conditions. In current-clamp experiments, 4-AP decreased Em (depolarization) and induced Ca(2+)-dependent action potentials; this depolarization increased [Ca2+]i in intact PASMCs. Neither ChTX nor the specific blocker of KATP channels, glibenclamide (2 to 10 mumol/L), caused membrane depolarization and the increase in [Ca2+]i. However, pretreatment of PASMCs with ChTX enhanced the 4-AP-induced increase in [Ca2+]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of cytochrome P-450 reduces voltage-gated K+ currents in pulmonary arterial myocytes

Cytochrome P-450 (P-450) is a NADPH-requiring and O2-dependent monooxygenase system. It is present in lung and has been postulated to act as an O2 sensor in hypoxic pulmonary vasoconstriction. To determine whether P-450 is involved in the regulation of voltage-gated K+ (KV) channel activity in pulmonary artery (PA) myocytes, we used the whole cell patch-clamp technique to evaluate the effects of P-450 inhibitors on KV channel currents (IKV) and membrane potential (Em). Bath application of the P-450 inhibitors clotrimazole, miconazole, and 1-aminobenzotriazole (1-ABT) significantly and reversibly inhibited steady-state IKV (IKss) and depolarized PA cells bathed in either Ca(2+)-containing (1.8 mM) or Ca(2+)-free [0.5-1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N'N'-tetraacetic acid present] bath solution. Clotrimazole (1 microM), miconazole (10 microM), and 1-ABT (1 mM) reversibly reduced IKss, elicited by a test potential of +80 mV, by 40, 70, and 31%, respectively. Pretreatment of PA smooth muscle cells with 10 mM 4-aminopyridine (4-AP) prevented the subsequent inhibitory effect of clotrimazole on IKV. However, pretreatment of the cells with 1 mM tetraethylammonium negligibly altered the effects of miconazole on IKV and Em. In current-clamp (I = 0) measurements, clotrimazole depolarized PA myocytes by 9 and 11 mV during perfusion with Ca(2+)-containing and Ca(2+)-free bath solution, respectively. 1-ABT also caused a 9-mV depolarization in PA myocytes bathed in Ca(2+)-free solution. These effects are similar to those induced by hypoxia, reduced glutathione, and 4-AP. Clotrimazole also decreased IKV and depolarized mesenteric arterial myocytes. These data raise the possibility that the P-450 system, due to its influence on IKV and sensitivity to O2 tension and NADPH, may play a role in linking the regulation of pulmonary vascular tone to the alteration of cellular redox status through a common pathway of KV channel activity.