Zung Vu Tran

Postoperative Delirium in the Elderly : Risk Factors and Outcomes

Objective:The purpose of this study was to describe the natural history, identify risk factors, and determine outcomes for the development of postoperative delirium in the elderly. Background:Postoperative delirium is a common and deleterious complication in geriatric patients. Methods:Subjects older than 50 years scheduled for an operation requiring a postoperative intensive care unit admission were recruited. After preoperative informed written consent, enrolled subjects had baseline cognitive and functional assessments. Postoperatively, subjects were assessed daily for delirium using the confusion assessment method-intensive care unit. Patients were also followed for outcomes. Results:During the study period, 144 patients were enrolled before major abdominal (40%), thoracic (53%), or vascular (7%) operations. The overall incidence of delirium was 44% (64/144). The average time to onset of delirium was 2.1 ± 0.9 days and the mean duration of delirium was 4.0 ± 5.1 days. Several preoperative variables were associated with an increased risk of delirium including older age (P < 0.001), hypoalbuminemia (P < 0.001), impaired functional status (P < 0.001), pre-existing dementia (P < 0.001), and pre-existing comorbidities (P < 0.001). In a multivariable logistic regression model, pre-existing dementia remains the strongest risk factor for the development of postoperative delirium. Worse outcomes, including increased length of stay (P < 0.001), postdischarge institutionalization (P < 0.001), and 6 month mortality (P = 0.001), occurred in subjects who developed delirium. Conclusions:In the current study, delirium occurred in 44% of elderly patients after a major operation. Pre-existing cognitive dysfunction was the strongest predictor of the development of postoperative delirium. Outcomes, including an increased rate of 6 month mortality, were worse in patients who developed postoperative delirium.

The Reno-Vascular A2B Adenosine Receptor Protects the Kidney from Ischemia

Background Acute renal failure from ischemia significantly contributes to morbidity and mortality in clinical settings, and strategies to improve renal resistance to ischemia are urgently needed. Here, we identified a novel pathway of renal protection from ischemia using ischemic preconditioning (IP). Methods and Findings For this purpose, we utilized a recently developed model of renal ischemia and IP via a hanging weight system that allows repeated and atraumatic occlusion of the renal artery in mice, followed by measurements of specific parameters or renal functions. Studies in gene-targeted mice for each individual adenosine receptor (AR) confirmed renal protection by IP in A1−/−, A2A−/−, or A3AR−/− mice. In contrast, protection from ischemia was abolished in A2BAR−/− mice. This protection was associated with corresponding changes in tissue inflammation and nitric oxide production. In accordance, the A2BAR-antagonist PSB1115 blocked renal protection by IP, while treatment with the selective A2BAR-agonist BAY 60–6583 dramatically improved renal function and histology following ischemia alone. Using an A2BAR-reporter model, we found exclusive expression of A2BARs within the reno-vasculature. Studies using A2BAR bone-marrow chimera conferred kidney protection selectively to renal A2BARs. Conclusions These results identify the A2BAR as a novel therapeutic target for providing potent protection from renal ischemia.

Resistance training and bone mineral density in women: a meta-analysis of controlled trials.

Kelley GA, Kelley KS, Tran ZV: Resistance training and bone mineral density in women: a meta-analysis of controlled trials. Am J Phys Med Rehabil 2001;80:65–77. The purpose of this study was to use meta-analysis to examine the effects of resistance training on bone mineral density at the femur, lumbar spine, and radius in pre- and postmenopausal women. Resistance training had a positive effect on bone mineral density at the lumbar spine of all women and at the femur and radius sites for postmenopausal women. It was concluded that resistance training has a positive effect on bone mineral density in women.

Walking and resting blood pressure in adults: a meta-analysis.

BACKGROUND The purpose of this study was to examine the effects of walking on resting systolic and diastolic blood pressure in adults. METHODS A total of 24 primary outcomes from 16 studies and 650 subjects (410 exercise, 240 control) met the criteria for inclusion: (1) randomized and nonrandomized controlled trials, (2) walking as the only intervention, (3) subjects apparently sedentary, (4) adult humans > or =18 years of age, (5) English-language studies published between January 1966 and December 1998, (6) resting blood pressure assessed, (7) training studies > or =4 weeks. RESULTS Using a random effects model, statistically significant decreases of approximately 2% were found for both resting systolic and diastolic blood pressure (systolic, mean +/- SEM = -3 +/- 1 mm Hg, 95% confidence interval: -5 to -2 mm Hg; diastolic, mean +/- SEM = -2 +/- 1 mm Hg, 95% confidence interval: -3 to -1 mm Hg). CONCLUSION Walking exercise programs reduce resting blood pressure in adults.

A survey of propofol abuse in academic anesthesia programs.

BACKGROUND:Although propofol has not traditionally been considered a drug of abuse, subanesthetic doses may have an abuse potential. We used this survey to assess prevalence and outcome of propofol abuse in academic anesthesiology programs. METHODS:E-mail surveys were sent to the 126 academic anesthesiology training programs in the United States. RESULTS:The survey response rate was 100%. One or more incidents of propofol abuse or diversion in the past 10 yr were reported by 18% of departments. The observed incidence of propofol abuse was 10 per 10,000 anesthesia providers per decade, a fivefold increase from previous surveys of propofol abuse (P = 0.005). Of the 25 reported individuals abusing propofol, 7 died as a result of the propofol abuse (28%), 6 of whom were residents. There was no established system to control or monitor propofol as is done with opioids at 71% of programs. There was an association between lack of control of propofol (e.g., pharmacy accounting) at the time of abuse and incidence of abuse at the program (P = 0.048). CONCLUSIONS:Propofol abuse in academic anesthesiology likely has increased over the last 10 yr. Much of the mortality is in residents. Most programs have no pharmacy accounting or control of propofol stocks. This may be of concern, given that all programs reporting deaths from propofol abuse were centers in which there was no pharmacy accounting for the drug.

Factors influencing patient decisions about the use of asthma controller medication.

BACKGROUND Patient nonadherence with asthma controller medication is pervasive and impedes successful adoption of national treatment guidelines. OBJECTIVE To survey adult patients with asthma about the factors influencing their decisions about when to use their asthma controller medications. METHODS Two hundred adults with asthma were randomly selected from a national database and were surveyed by telephone about medication use, barriers to adherence, and treatment preferences. RESULTS Adherence to daily controller medication in the group was generally well below the prescribed level despite the fact that many had relatively severe asthma and inadequately controlled symptoms. Thirty percent of the respondents indicated that they had been instructed by their physician to use their controller medication intermittently as guided by their symptoms. Most respondents expressed a desire to be more in control of their treatment and for that treatment to be more immediately effective and long-lasting but did not perceive inadequate information to be a barrier to adherence. CONCLUSION These insights into patient perception and motivation suggest the importance of developing treatment plans that allow patients some degree of control over medication use.

Aerobic exercise and normotensive adults : a meta-analysis

Using the meta-analytic approach, the purpose of this study was to examine the effects of aerobic exercise on resting systolic (SYS) and diastolic (DIA) blood pressure in normotensive adults: The results of 35 human clinical training studies published in English-language journals between 1963 and 1992 and representing 1,076 subjects (800 exercise, 276 control) met criteria for inclusion. Across all categories and designs, statistically significant post-exercise reductions were found for both SYS and DIA blood pressure (mean +/- SD, SYS: -4.4 +/- 6.6 mm Hg, 95% CI, -6.2 to -2.6 mm Hg; DIA: -3.2 +/- 3.2 mm Hg, 95% CI, -4.0 to -2.2 mm Hg). When partitioned according to type of study: 1) (randomized controlled trials (RCT), 2) controlled trials (CT), and 3) no controls (NC), the following changes were noted: RCT, SYS: -4.5 +/- 7.2 mm Hg, 95% CI, -7.1 to -1.2 mm Hg; DIA: -3.8 +/- 2.9 mm Hg, 95% CI, -5.0 to -2.6 mm Hg; CT, SYS: -2.8 +/- 6.9 mm Hg, 95% CI, -10.0 to 4.4 mm Hg; DIA: -5.0 +/- 3.7 mm Hg, 95% CI, -8.9 to -1.1 mm Hg; NC, SYS: -4.7 +/- 6.1 mm Hg, 95% CI, -7.5 to 1.9 mm Hg; DIA: -1.7 +/- 3.0 mm Hg, 95% CI, -3.2 to -0.36 mm Hg. We concluded that aerobic exercise results in small reductions in resting SYS and DIA blood pressure among normotensive adults.

A multicenter evaluation of safety of early extubation in liver transplant recipients

Small single‐institutional studies performed prior to the introduction of organ allocation using the Model for End‐Stage Liver Disease (MELD) suggest that early airway extubation of liver transplant recipients is a safe practice. We designed a multicenter study to examine adverse events associated with early extubation in patients selected for liver transplantation using MELD score. A total of 7 institutions extubated all patients meeting study criteria and reported adverse events that occurred within 72 hours following surgery. Adverse events were uncommon: occurring in only 7.7% of 391 patients studied. Most adverse events were pulmonary or surgically related. Pulmonary complications were usually minor, requiring only an increase in ambient oxygen concentration. The majority of surgical adverse events required additional surgery. Analysis of a limited set of perioperative variables suggest that blood transfusions and technical factors were associated with an increased risk of adverse events. In conclusion, while early extubation appears to be safe under specified circumstances, there are performance differences between institutions that remain to be explained. Liver Transpl 13:1557–1563, 2007.

Chronic renal dysfunction following liver transplantation

Abstract:  With most of the immunosuppressive protocols consisting of calcineurin inhibitors (CI), nephrotoxicity has become a major long‐term complication often compromising outcome. In a single‐center retrospective study, we reviewed 1173 liver transplantations to identify variables indicative for the occurrence of chronic renal dysfunction (CRD) (defined as ≥1 episode of serum creatinine increase ≥1.8 mg/dL ≥2 wk). Chronic renal dysfunction was found in 137 (11.7%) of all transplants [82 (7%) early (after 3–12 months), 55 (4.7%) late‐onset (>12 months)]. Compared to 5‐/10‐yr survival rates in non‐CRD transplants (84/74%) survival was significantly decreased in early (66/46%), but unchanged in late‐onset CRD (98/86%). Rates of alcoholic cirrhosis and prior renal dysfunction were significantly increased in patients with CRD. In a multivariate logistic regression analysis, only cyclosporine A (CyA) as immunosuppression remained an independent risk factor. No correlations to age, gender, rejection/retransplantation or diabetes were found. Surprisingly, renal function (creatinine) showed no difference between patients on CI monotherapy (FK/CyA) compared to those who had mycophenolate mofetil (MMF) added. In liver transplantation, early onset CRD significantly compromises survival. CyA‐based immunosuppression appears to have a stronger impact than FK. The fact that patients with long‐term severe chronic renal dysfunction failed to improve under MMF rescue therapy emphasizes the importance of new diagnostic strategies to earlier identify at‐risk patients.

Pressor response to isometric exercise in patients with multiple sclerosis.

The purpose of this study was to determine whether patients with multiple sclerosis (MS) would show attenuated heart rate and/or pressor responses to isometric handgrip exercise. Patients with MS (30 males, 74 females, aged 23-61 yr) and control subjects (9 males, 16 females, aged 25-47 yr) performed isometric handgrip exercise at 30% of maximal voluntary contraction (MVC) to fatigue. Systolic, diastolic, and mean arterial pressure (MAP) increased linearly in both groups, but were significantly lower (P < 0.05) in patients with MS at 20%, 40%, 60%, 80%, and 100% of exercise duration. Mean change in MAP at fatigue was +47.9 mm Hg for controls and +28.2 mm Hg for patients with MS, with 18 patients with MS between -6 mm Hg and +15 mm Hg. Heart rate increased normally in patients with MS. To predict change in MAP at fatigue in patients with MS, stepwise regression analysis using six variables yielded an R2 of 0.26. These data suggest that in some patients MS lesions exist in areas of autonomic cardiovascular control that result in attenuated pressor responses to exercise. In 17% of patients tested, attenuation was profound. Data also suggest an abnormal dissociation between the heart rate and pressor response to static work in patients with MS.