Faculty Bibliography

INTRODUCTION: We examined pulmonary diffusing capacity (D(LCO)) and its partition in pulmonary vascular diseases without evident parenchymal disease to assess the pattern and proportionality of change in membrane diffusion (D(m)) and capillary blood volume (V(c)). Disproportionate reduction in D(m) relative to V(c) (low D(m)/V(c)) in these diseases has been attributed to associated alveolar membrane/parenchymal disease, thus providing a potentially important diagnostic tool. METHODS: Diseases included: idiopathic pulmonary arterial hypertension (n=6), chronic thromboembolic disease (n=5), and intravenous drug use (n=14), providing a spectrum of pulmonary vascular diseases. V(c) and D(m) were determined as described by Roughton and Forster. RESULTS: All diseases showed a reduced V(c) (59+/-10, 69+/-14, 71+/-21 % predicted, respectively) and D(m) (76+/-22, 53+/-19, 63+/-16 % predicted, respectively) with no differences between groups (p>0.05). Disproportionate reduction of D(m) (D(m)/V(c) % predicted <1) was seen in all diseases (range 0.36-1.89). A mathematical analysis is presented to illustrate that changes in vascular geometry may additionally influence the proportionality of changes in D(m) and V(c). The mathematical analysis suggests that when reduction in patency of some vessels co-exits with compensatory dilatation of the remaining vasculature, a disproportionate reduction in D(m) relative to V(c) may result. CONCLUSIONS: The balance between vascular curtailment and compensatory dilatation may contribute to the variability of the D(m)/V(c) relationship seen in pulmonary vascular disease. Disproportionate reduction in D(m) relative to V(c) may result from this imbalance and need not imply subclinical alveolar membrane and/or parenchymal disease.

OBJECTIVE: Obese patients without clinically apparent heart disease may have a high output state and elevated total and central blood volumes. Central circulatory congestion should result in elevated pulmonary diffusing capacity (DLCO) and capillary blood volume (Vc) reflecting pulmonary capillary recruitment; however, the effect on membrane diffusion (Dm) is uncertain. We examined DLCO and its partition into Vc and Dm in 13 severely obese subjects (BMI = 51 +/- 14 kg/m2) without manifest cardiopulmonary disease before and after surgically induced weight loss. RESEARCH METHODS AND PROCEDURES: DLCO and its partition into Vc and Dm [referenced to alveolar volume (VA)] as described by Roughton and Forster, total body water by tritiated water, and fat distribution by waist-to-hip ratio were performed. RESULTS: Despite normal DLCO (mean 98 +/- 16% predicted), Vc/VA was increased (mean 118 +/- 30% predicted), and Dm/VA was reduced (mean 77 +/- 34% predicted). Nine of 13 subjects were restudied after weight loss (mean 52 +/- 43 kg); Vc/VA decreased to 89 +/- 18% predicted (p = 0.01), and Dm/VA increased to 139 +/- 30% predicted (p < 0.01). Increasing total body water was associated with both increasing Vc (r = 0.74, p = 0.01) and increasing waist-to-hip ratio (r = 0.65, p = 0.02), indicating that circulatory congestion increases with increasing central obesity. DISCUSSION: Severely obese subjects without manifest cardiopulmonary disease may have increased Vc indicating central circulatory congestion and reduced Dm suggesting associated alveolar capillary leak, despite normal DLCO. Reversibility with weight loss is in accord with reversibility of the hemodynamic abnormalities of obesity.

Acute hypercapnia may develop during periodic breathing from an imbalance between abnormal ventilatory patterns during apnea and/or hypopnea and compensatory ventilatory response in the interevent periods. However, transition of this acute hypercapnia into chronic sustained hypercapnia during wakefulness remains unexplained. We hypothesized that respiratory-renal interactions would play a critical role in this transition. Because this transition cannot be readily addressed clinically, we modified a previously published model of whole-body CO2 kinetics by adding respiratory control and renal bicarbonate kinetics. We enforced a pattern of 8 h of periodic breathing (sleep) and 16 h of regular ventilation (wakefulness) repeated for 20 days. Interventions included varying the initial awake respiratory CO2 response and varying the rate of renal bicarbonate excretion within the physiological range. The results showed that acute hypercapnia during periodic breathing could transition into chronic sustained hypercapnia during wakefulness. Although acute hypercapnia could be attributed to periodic breathing alone, transition from acute to chronic hypercapnia required either slowing of renal bicarbonate kinetics, reduction of ventilatory CO2 responsiveness, or both. Thus the model showed that the interaction between the time constant for bicarbonate excretion and respiratory control results in both failure of bicarbonate concentration to fully normalize before the next period of sleep and persistence of hypercapnia through blunting of ventilatory drive. These respiratory-renal interactions create a cumulative effect over subsequent periods of sleep that eventually results in a self-perpetuating state of chronic hypercapnia.

BACKGROUND: Elder neglect accounts for over 70% of all adult protective services reports in the nation annually, and it has been estimated that there are over 70,000 new cases each year. The purpose of this study was to conduct elder neglect research in the emergency department (ED), using a dyadic vulnerability/risk-profiling framework for elder neglect. METHODS: Patients were recruited through four EDs in New York and Tampa from the beginning of February 2001 through the end of September 2003. Demographics, a Mini-Mental Status Examination score, and an initial elder assessment screen were collected. The diagnosis of neglect was then made by a Neglect Assessment Team (NAT) comprising a nurse, physician, and social worker, with extensive clinical experience in elder neglect. RESULTS: Of the 3664 ED screens of adults 70 years and older, 405 (11%) met the inclusion criteria and agreed to participate. Neglect was diagnosed by the NAT in 86 of the 405 cases reviewed. Demographic differences between neglect versus no neglect cases were examined using Fisher's exact test, and differences emerged between the 2 groups. CONCLUSION: This study documents the underreporting of cases of neglect as evidenced by differences in diagnoses by screeners versus experts. The research assistants screened positive for neglect in 5% (N=22) of the 405 cases. The NAT made the diagnosis of neglect in 22% (86/389) of the cases. This markedly different rate of neglect may mean that ED screens are important but may underestimate the true number of cases. Conversely, an NAT may make the diagnosis of neglect in an older adult more often given a higher sensitivity and a more robust knowledge base of the problem.

PURPOSE: Neglect of older adults accounts for 60% to 70% of all elder-mistreatment reports made to adult protective services. The purpose of this article is to report data from research, using a risk-and-vulnerability model, that captures the independent contributions of both the elder and the caregiver as they relate to the outcome of neglect. METHODS: Between February 2001 and September 2003, older adults were screened and recruited through four emergency departments in New York and Tampa. The diagnosis of neglect was made by an expert neglect-assessment team. Elders and their caregivers were then scheduled for separate face-to-face interviews after discharge. RESULTS: Constructs within the risk-and-vulnerability model were examined for scale-score significance based on the outcome diagnosis of neglect. In the risk domain, caregivers' functional status, childhood trauma, and personality were statistically significant. In the vulnerability domain, the elders' cognitive status, functional status, depression, social support, childhood trauma, and personality were significant. IMPLICATIONS: Findings from this study underscore the value of interdisciplinary assessment teams in emergency departments for screening elder neglect, with attention given to risk factors related to the caregiver and elder vulnerability factors, including reports of childhood trauma. The risk-and-vulnerability model may provide a link between the caregiving and neglect research. Data should be collected independently from both members of the elder-caregiver dyad in order for clinicians to understand factors related to elders who receive the diagnosis of neglect from interdisciplinary teams.