High-intensity inspiratory muscle training in patients with chronic obstructive pulmonary disease and severely reduced function.

PURPOSE: This study examined the effects of inspiratory muscle training (IMT) with high-intensity inspiratory pressure loads on respiratory muscle performance and exertional dyspnea. METHODS: This was a randomized single-blind clinical trial. Twenty-seven patients with chronic obstructive pulmonary disease (18 men, 9 women) with severe to very severe airflow obstruction and severely limited functional performance were assigned randomly to an IMT group (n = 12) or an educational control group (n = 15). The IMT group trained with a threshold loaded device for 30 minutes a day for 16 weeks using interval training techniques. Training was initiated with inspiratory pressure loads equal to 30% of maximal inspiratory pressure (Plmax) and increased as tolerated to 60% of Plmax. Dependent variables were measured before and after 4 months of IMT: inspiratory muscle strength (Plmax), respiratory muscle endurance (discontinuous incremental threshold loading test [DC-ITL]), dyspnea (Chronic Respiratory Disease Questionnaire [CRQ]), and the Borg Category-Ratio Scale ratings of perceived breathing difficulty (RPBD) at equal loads during the DC-ITL. RESULTS: In the IMT group, Plmax increased from 64 +/- 15 to 75 +/- 17 cm H2O (P < .05), performance on the DC-ITL test increased from a maximal load of 37 +/- 12 to 53 +/- 13 cm H2O (P < .05), RPBD decreased from 5.5 +/- 2.5 to 3.8 +/- 2.6 for equal loads on the DC-ITL (P < .05) and the CRQ Dyspnea Scale improved from 18.1 +/- 5.1 to 22.4 +/- 5.2 (P < .05). CONCLUSIONS: Inspiratory muscle training at high-intensity loads significantly improved inspiratory muscle strength, respiratory muscle endurance, and respiratory symptoms during daily activities and respiratory exertion.

Malnutrition in chronic obstructive pulmonary disease: adding insult to injury.

Weight loss in patients with chronic obstructive pulmonary disease has a negative effect on the clinical course of the patient. Causes of weight loss in this population are known to include the effects of an energy imbalance, increased cytokines, hypoxia, and glucocorticoid use. This article delineates mechanisms included in these processes and highlights specific deleterious aspects of each. In addition, the effects of the following therapies are discussed in light of recent research findings: nutrition support, anabolic steroids, recombinant human growth hormone, and polyunsaturated fatty acids. This review summarizes the current state of knowledge in this area.

Cycle ergometer and inspiratory muscle training in chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD) the intensity of aerobic training is limited by dyspnea. Improving strength of the inspiratory muscles could enhance aerobic exercise training by reducing exercise-related dyspnea. We examined effects of home-based inspiratory muscle training (IMT) and cycle ergometry training (CET) in 53 patients with moderate to severe COPD (FEV(1)% pred, 50 +/- 17 [mean +/- SD]). Patients were randomly assigned to 4 mo of training in one of four groups: IMT, CET, CET + IMT, or health education (ED). Patients were encouraged to train to the limits of their dyspnea. Inspiratory muscle strength and endurance increased in IMT and CET + IMT groups compared with CET and ED groups (p < 0. 01). Peak oxygen uptake increased and heart rate, minute ventilation, dyspnea, and leg fatigue decreased at submaximal work rates in the CET and CET + IMT groups compared with the IMT and ED groups (p < 0. 01). There were no differences between the CET and CET + IMT groups. Home-based CET produced a physiological training effect and reduced exercise-related symptoms while IMT increased respiratory muscle strength and endurance. The combination of CET and IMT did not produce additional benefits in exercise performance and exercise-related symptoms. This is the first study to demonstrate a physiological training effect with home-based exercise training.

Nutritional assessment of the critically ill patient.

Nutritional assessment can be incorporated into the assessments performed daily by the critical care nurse for every patient. Identification of nutritional deficits will lead to timely interventions and will facilitate recovery and early discharge. The metabolic responses to starvation and stress are reviewed, and bedside techniques for nutritional assessment are outlined. General guidelines for nutritional support and parameters for monitoring the effectiveness of nutritional therapies are defined.

Respiratory muscle strength in older adults.

Gender-related effects and two measures of muscularity, handgrip strength and fat-free mass (FFM), were examined to determine their relationship to respiratory muscle strength. Subjects were 101 healthy older adults. In 75 subjects, the magnitude of learning effect was examined over four weekly sessions. Maximal inspiratory pressure (PImax) was lower with increasing age in women, and maximal expiratory pressure (PEmax) was lower with increasing age in both genders. The PEmax correlated with handgrip strength and FFM in men only. Performance of PImax plateaued by the third visit in both men and women. Performance of PEmax plateaued by the third measure in women and was unchanged across four measurements for men.

Surveillance around hazardous waste sites: geographic information systems and reproductive outcomes.

The purpose of this paper is to discuss the potential for integrating surveillance techniques in reproductive epidemiology with geographic information system technology in order to identify populations at risk around hazardous waste sites. Environmental epidemiologic studies have had problems with estimating or measuring exposures to individuals, and of detecting effects when the exposure is low, but continuous. In addition, exposures around hazardous waste sites are complex and frequently involve chemical mixtures. The birth weight of human babies has been reported to be sensitive to many environmental influences. Birth weight can be analyzed as a continuous variable or as a dichotomous one using the standard cutpoint of 2500 g or less to indicate low birth weight. It has the potential to be a powerful surveillance tool since exposures to the fetus reflect maternal and paternal exposures. The advent of recent environmental regulations pertaining to hazardous waste sites has greatly increased the availability of environmental data for many sites. The major problem with incorporating these data into epidemiologic studies has been with the logistics of data management and analysis. Computer-assisted geographic information systems hold promise in providing capabilities needed to address the data management and analysis requirements for effective epidemiologic studies around to hazardous waste sites.

Switch region content of hybridomas: the two spleen cell Igh loci tend to rearrange to the same isotype.

We have examined the switch region content of 25 hybridomas that secret antibodies of various isotypes with specificity for phosphocholine or glycoproteins of herpes simplex virus. These Southern hybridization experiments included probes for the murine JH region as well as probes for the mu, gamma 3, gamma 1, gamma 2b, gamma 2a, and alpha switch regions. For 22 of the hybridomas, the deletion model of the heavy chain switch fits the data well--all switch regions upstream of the rearranged (and expressed) switch regions are deleted and all switch regions downstream remain in the germline configuration. As exceptions to a simple deletion model of the switch recombination, we have observed two, and perhaps three, examples of switch region rearrangements downstream of an expressed heavy chain gene. The 25 hybridoma DNA samples include 28 rearranged gamma switch regions; the sizes of at least 25 of these rearranged fragments are consistent with recombination in the tandemly repeated sequences associated with gamma genes. For those hybridomas with two spleen cell-derived Igh loci, including three mu-expressers, three gamma 3-expressers, four gamma 1-expressers, and one gamma 2b-expresser, the two loci tend to be rearranged to the same switch region, suggesting that the heavy chain switch rearrangement is an isotype-specific event. The exceptions within this group include three hybridomas in which the switch seems to be incomplete--on one chromosome the JH complex is rearranged to the S gamma 3 region, while on the other it remains associated with the S mu region. A second group of hybridomas, which includes four gamma 3-expressers, have both gamma 3 and gamma 1 switch rearrangements. Each of these four hybridomas includes three rearranged JH segments, suggesting that they may be the result of an unusual differentiative pathway or a technical artifact. These experiments suggest that the heavy chain switch rearrangement in normal spleen cells is a deletion event that occurs within tandemly repeated elements. The rearrangement is mediated by factors with partial, or perhaps complete, isotype specificity.