AimsBone status has not been comprehensively studied in chronic heart failure (CHF). In CHF men, we evaluated bone status, bone loss over time, and their clinical and hormonal determinants. Methods and resultsBone mineral content (BMC) and bone mineral density (BMD) of arms, legs, trunk, and total body were examined using dual-energy X-ray absorptiometry in 187 men with CHF [age: 60+11 years, left ventricular ejection fraction (LVEF): 32+7%, New York Heart Association (NYHA) class (I/II/III/IV): 20/76/76/15] and in 21 age-matched male controls without CHF. Men with CHF had reduced BMD and BMC compared with controls (P , 0.05). Reduced BMD and BMC were independently determined by CHF severity (high NYHA class and impaired LVEF), reduced lean tissue mass, low serum dehydroepiandrosterone sulphate, total testosterone (TT), and estimated free testosterone (eFT) (all P , 0.05). Bone status was reassessed in 60 patients who survived .2 years from the initial evaluation. Significant bone loss over time (a reduction in BMC total 1%/year) occurred in 35% of CHF men. Advanced NYHA class (P , 0.05) and reduced serum TT and eFT (P , 0.0001) at baseline predicted augmented bone loss. ConclusionIn CHF men, reduced BMD and BMC constitute an element of generalized body wasting, determined mainly by advanced heart failure and androgen deficiencies. Significant bone loss over time frequently occurs in CHF men and is related to testosterone depletion and disease severity.--

The simple T-piece is frequently used as a weaning system during respirator treatment. It is modified with an expiratory non-compliant reservoir (EnCR), an inspiratory compliant reservoir (ICR) and/or an expiratory one-way valve. The distribution of expiratory gases and rebreathing were studied in a model set-up in the corresponding systems at different fresh gas flows (FGF) and tidal volumes (VT). An EnCR produces no change, whereas an ICR causes the expiratory gas to flow into the inspiratory limb, an effect which is intensified by the presence of an expiratory valve. With a falling FGF and a rising VT, increasing amounts of expiratory gas are found in the inspiratory limb in the modifications with an ICR. However, this gives rise to rebreathing in the valve modification with a low FGF and high VT. The modification of the T-piece with an ICR but without a one-way valve is advantageous, as this system combines only slight dilution via the expiratory limb and a minimal risk of rebreathing.

Including a venturi injector in a Magill breathing attachment reduces the requirement of compressed gases to 40% of that normally used: 100-120 ml x kg-1 x min-1. The entrainment of ambient air through the venturi injector enables the supply of an adequate flow of gas mixture to the patient. In 10 awake volunteers and 12 patients under N2O/halothane anaesthesia, it was demonstrated that a fresh gas flow from the anesthetic machine of 40 ml x kg-1 x min-1 is sufficient to prevent rebreathing during spontaneous respiration, when the venturi injector is included in the Magill attachment.

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