Health and function in the old and very old.

This report advocates conceptual separation and parallel assessment of medically diagnosed health conditions and functional disability in clinical and epidemiological studies of the aged. Data from a study of urban elderly are presented to demonstrate how this can be done and to reexamine the meaning of self-reported illness and disability. One hundred thirteen subjects 74 to 95 years old, recruited from a longitudinal study of a representative sample of the elderly population of Cleveland, Ohio, participated in structured interviews and epidemiologically based medical examinations, conducted by a physician-nurse team at the place of residence. The presence or absence of 11 common chronic conditions was determined according to preestablished criteria, by self-report and, separately, by medical diagnostic evaluation. Functional disability was estimated by self-report and by physician-nurse assessment, using established measures of mobility and activities of daily living. Results indicate that interview self-report can provide useful estimates of the prevalence of medical conditions and functional disabilities in elderly populations, although self-report alone is not a sufficiently sensitive measure to be used for case-finding or diagnosis. When functional disabilities are matched against the specific medical conditions that cause them and disease-specific mortality is also taken into account, a three-dimensional classification results that has implications for future clinical and survey work with the elderly.

Percutaneous dilation of benign biliary strictures.

Percutaneous balloon dilation of benign biliary strictures was successful in 15 of 18 patients in whom the procedure was attempted. Successful dilation was achieved in nine of 11 patients who had biliary enteric strictures, with follow-up of 22-55 months (mean, 35.4 months) after catheter removal in seven patients. Five of six strictures in the biliary tree that developed after surgery were successfully dilated, with long-term follow-up available in two patients (58 and 42 months). A patient with an inflammatory common bile duct stricture that was successfully dilated was followed up for 18 months. Percutaneous dilation of biliary tract strictures is a promising technique with good long-term results and may be the initial treatment of choice in biliary stricture management.

Ventilation inhomogeneity: alveolar mechanics and gas distribution.

The effects of regional lung differences in alveolar mechanics on the transpulmonary pressure-volume (Ptp-V) relationship and the single-breath washout (SBW) of nitrogen were investigated by mathematical modeling and postmorten human lung experiments. Regional nonuniformity in alveolar collapse and re-opening were associated with differences in gravitational stress or elasticity. Model simulations predict that neither type of regional nonuniformity qualitatively affects the shape of the Ptp-V curve, but does affect the terminal (or small-volume) portion of the SBW. Comparisons of characteristics of the Ptp-V and SBW curves indicate that regional nonuniformity in alveolar collapse is an important mechanism associated with ventilation inhomogeneity.

Relationship of ventilation inhomogeneity to morphologic variables in excised human lungs.

Ventilation inhomogeneity, as assessed by the regional distribution of 133Xe and the single breath washout (SBW) curve, is compared with the morphologic aspects in excised human lungs. Morphologic measurements include central airway diameter, bronchial gland area, peripheral airway diameter, and the alveolar surface-to-volume ratio. Lung inflation with a constant concentration of 133Xe results in relatively more 133Xe distributed to the lung base than to the apex. Neither the vertical gradient in ventilation nor other interregional inhomogeneities in 133Xe distribution are correlated with morphologic variations in the lung. Also, interregional inhomogeneities of 133Xe distribution do not correlate with phase III slope of the SBW curve. This suggests that the phase III slope is determined primarily by intraregional ventilation inhomogeneities. Within the phase IV region of the SBW curve two distinct inflections are identified: an inflection at volume V1 and another sharper inflection at volume V2. Both the phase III slope and V2 correlate significantly (p less than 0.05) with peripheral airway diameter, indicating that parameters of the SBW curve do assess peripheral airway properties.

Human lung pressure-volume relationships: alveolar collapse and airway closure.

We investigated the effect of airway closure and alveolar collapse on the large-volume deflation and inflation transpulmonary pressure-volume (Ptp-V) curves of five postmortem excised human lungs. For stepwise static cycles, no inflection occurred on the deflation curve, while either one or two inflections occurred on the inflation curve. These relations were stimulated by a multicompartment model, which assumed a bimodal distribution of compartmental collapse-pressure differences. The simulations indicate that alveolar collapse can occur without causing an inflection on the deflation curve and that hysteresis in reopening of collapsed alveoli on inflation can account for a major portion of Ptp-V hysteresis. In contrast, for slow dynamic cycles, an inflection occurred on the experimental deflation Ptp-V curve, and when inflations were begun at sufficiently low volumes, volume did not change until a threshold pressure difference was reached about which PtP began to oscillate as lung volume increased. These differences in the stepwise static and dynamic Ptp-V curves can result from sustained airway closure on deflation and popping-opening on inflation.

Moment analysis of multibreath lung washout.

A moment analysis of multibreath nitrogen washout has been developed to provide a sensitive, quantitative measure that characterizes the inhomogeneity of pulmonary ventilation. To test the analysis scheme, we studied 5 normal subjects and 16 subjects with obstructive lung disease who performed each washout test at constant tidal volume and frequency. Subjects executed the wahout test 3-4 times at different tidal volumes (0.5-1.5 liters) and frequencies (10-30/min). Plotting washout data as dimensionless end-tidal nitrogen concentration versus the cumulative expired volume normalized by the functional residual capacity (CEV/FRC) renders the washout curves of each individual almost superposab le despite changes in breathing frequency and tidal volume from test to test. The dimensionless washout curve is treated as a distribution from which the normalized first (M1/Mo) and second (M2/Mo) moments are obtained. These parameters clearly display diagnostic clustering for various disease states. With respect to the normal subjects, the magnitude of M1/Mo was 26% greater for asthmatics, 38% greater for bronchitics, and 52% greater for emphysematics. This moment analysis provides an objective, quantitative assessment of the extent of ventilation inhomogeneities without specification of a lung model.