Skeletal muscle oxidative capacity, fiber type, and metabolites after lung transplantation.

Lung transplant (LTx) recipients have a low peak work rate, peak oxygen consumption (V O2peak), and early lactate threshold on incremental exercise. We hypothesized that LTx recipients have reduced oxidative function and altered fiber type proportion in peripheral skeletal muscle. Seven stable LTx recipients and seven age- and sex-matched control subjects were studied. Incremental exercise testing with arterialized venous sampling and a resting quadriceps femoris punch muscle biopsy were performed. Muscle specimens were analyzed for fiber type proportion, metabolites, oxidative and glycolytic enzyme activities, and mitochondrial ATP production rate (MAPR) using standard techniques. The results showed that mean V O2peak in LTx recipients was 52% of control subjects. Compared with the control subjects, LTx skeletal muscle exhibited: (1) a lower MAPR; (2) lower activity of the mitochondrial enzymes glutamate dehydrogenase (GDH), citrate synthase (CS), 2-oxogluterate dehydrogenase (OGDH), and 3-hydroxyacyl-CoA-dehydrogenase (HAD). There was no difference in the activities of anaerobic enzymes, except for higher phosphofructokinase activity; (3) a lower proportion of type I fibers; (4) a higher lactate and inosine monophosphate (IMP) content and a lower ATP content at rest indicating a high reliance on anaerobic metabolism. The reduced type I fiber proportion and severely reduced mitochondrial oxidative capacity may play an important role in exercise limitation after LTx.

A cost-analysis of two approaches to infection control in a lung function laboratory.

BACKGROUND: The Thoracic Society of Australia and New Zealand (TSANZ) guidelines for infection control in respiratory laboratories are based on a 'Universal Precautions' approach to patient care. This requires that one-way breathing valves, flow sensors, and other items, be cleaned and disinfected between patient use. However, this is impractical in a busy laboratory. The recent introduction of disposable barrier filters may provide a practical solution to this problem, although most consider this approach to be an expensive option. AIM: To compare the cost of implementing the TSANZ infection control guidelines with the cost of using disposable barrier filters. METHODS: Costs were based on the standard tests and equipment currently used in the lung function laboratory at The Alfred Hospital. We have assumed that a barrier filter offers the same degree of protection against cross-infection between patients as the TSANZ infection control guidelines. Time and motion studies were performed on the dismantling, cleaning, disinfecting, reassembling and re-calibrating of equipment. Conservative estimates were made as to the frequency of replacing pneumotachographs and rubber mouthpieces based on previous equipment turnover. Labour costs for a scientist to reprocess the equipment was based on $20.86/hour. The cost of employing a casual cleaner at an hourly rate of $14.07 to assist in reprocessing equipment was also investigated. The new high efficiency HyperFilter disposable barrier filter, costing $2.95 was used in this cost-analysis. RESULTS: The cost of reprocessing equipment required for spirometry alone was $17.58 per test if a scientist reprocesses the equipment, and $15.56 per test if a casual cleaner is employed to assist the scientist in performing these duties. In contrast, using a disposable filter would cost only $2.95 per test. Using a filter was considerably less expensive than following the TSANZ guidelines for all tests and equipment used in this cost-analysis. CONCLUSIONS: The TSANZ infection control guidelines are expensive and impractical to implement. However, disposable barrier filters provide a practical and inexpensive method of infection control.

Exercise, potassium, and muscle deconditioning post-thoracic organ transplantation.

Although muscle deconditioning appears to significantly limit peak exercise performance post-thoracic organ transplantation, few confirmatory data exist. Potassium (K+) regulation during exercise may reflect muscle deconditioning, since both peak plasma K+ concentration ([K+]) and the increase in plasma [K+] relative to energy expenditure (delta [K+]/W) are reduced in healthy individuals after training. This study compares delta [K+]/W during graded exercise and the change in [K+] (delta [K+]) during both exercise and recovery in 12 heart transplant (HT) recipients, 14 lung transplant (LT) recipients, and 7 healthy subjects. Plasma [K+] was determined from arterial blood sampled at rest; during the final 15 s of each power output; and at 1, 2, and 5 min postexercise. Peak oxygen consumption was significantly lower (P < 0.0001), whereas delta [K+]/W was significantly higher (P < 0.002) among the HT and LT groups. When delta [K+] during recovery was expressed relative to delta [K+] detected during activity, no difference at 1, 2, or 5 min postexercise was detected, although the absolute fall in plasma [K+] was greater among the healthy subjects in the 1st min (P < 0.0001). The rate of delta [K+] during recovery appears to reflect the rise seen during activity in all groups. These results suggest that [K+] regulation is altered during exercise in both HT and LT recipients and may reflect muscle deconditioning.