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Biomedical subjects

D B Nelson

Publications and source records attributed to D B Nelson.

At least 19 recordsLinked to original sources
PubMed2003

Disability after clinical fracture in postmenopausal women with low bone density: the fracture intervention trial (FIT).

Relatively little is known about outcomes following clinical osteoporotic fractures at nonhip, nonvertebral skeletal sites. To address this issue, we prospectively assessed post-fracture disability at multiple skeletal sites in a population of 909 older (aged 55-81 years), community-dwelling women with low femoral neck bone mineral density who had experienced a fracture while enrolled in the Fracture Intervention Trial (FIT). FIT is a randomized, double-masked, placebo-controlled trial that was designed to determine the effect of alendronate on fracture incidence, and the current study was conducted as a secondary analysis of FIT data. Following incident clinical fractures, FIT participants were followed prospectively for assessment of site-specific, fracture-related disability. Measures of disability were self-reported days hospitalized or confined to bed because of the fracture ('bed days') and days of reduced usual activities because of the fracture ('limited activity days'). Of fracture types evaluated, those of the hip resulted in the highest percentage of subjects with any bed days or limited activity days after fracture (94% with any bed days and 100% with any limited activity days), though the mean number of bed days and limited activity days appeared highest after lumbar vertebral fractures (25.8 mean bed days and 158.5 mean limited activity days). Substantial disability also was reported after fractures of thoracic vertebrae, humerus, distal forearm, ankle and foot. Within fracture types, post-fracture disability was highly variable, ranging from none to more than 6 months.

Activities of Daily Living↗
PubMed2002

Sex hormones, hemostasis and early pregnancy loss.

AIMS: This study was designed to determine the association between coagulation factors and spontaneous abortion adjusting for sex steroids and to examine the influence of sex hormones on coagulation factors early in pregnancy. METHODS: Pregnant women presenting to the emergency department at the Hospital of the University of Pennsylvania were recruited and followed through 22 weeks gestation. Cases were women who experienced a spontaneous abortion (n=29) and controls were women who maintained their pregnancy to 22 weeks gestation (n=89). Participants completed a baseline questionnaire to assess demographic, reproductive, and drug use information. Blood samples measured estradiol, progesterone, fibrinogen, and factor VII antigen. RESULTS: Cases of spontaneous abortion had significantly lower levels of estradiol, progesterone, fibrinogen and factor VII antigen compared to controls. The relationship between low levels of fibrinogen and factor VII antigen was diminished adjusting for the sex steroids. Regression analyses found low progesterone was the primary prospective marker for early pregnancy loss among our study population. CONCLUSIONS: The relationship between coagulation factors and spontaneous abortion was reduced after adjustment for progesterone suggesting that progesterone mediates the relationship between low levels of coagulation factors and spontaneous abortion. Progesterone seems to be the primary marker for a spontaneous abortion among women seeking emergent care.

Abortion, Spontaneous↗
PubMed2001

Intussusception among infants given an oral rotavirus vaccine.

BACKGROUND: Intussusception is a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment. Our investigation began on May 27, 1999, after nine cases of infants who had intussusception after receiving the tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV) were reported to the Vaccine Adverse Event Reporting System. METHODS: In 19 states, we assessed the potential association between RRV-TV and intussusception among infants at least 1 but less than 12 months old. Infants hospitalized between November 1, 1998, and June 30, 1999, were identified by systematic reviews of medical and radiologic records. Each infant with intussusception was matched according to age with four healthy control infants who had been born at the same hospital as the infant with intussusception. Information on vaccinations was verified by the provider. RESULTS: Data were analyzed for 429 infants with intussusception and 1763 matched controls in a case-control analysis as well as for 432 infants with intussusception in a case-series analysis. Seventy-four of the 429 infants with intussusception (17.2 percent) and 226 of the 1763 controls (12.8 percent) had received RRV-TV (P=0.02). An increased risk of intussusception 3 to 14 days after the first dose of RRV-TV was found in the case-control analysis (adjusted odds ratio, 21.7; 95 percent confidence interval, 9.6 to 48.9). In the case-series analysis, the incidence-rate ratio was 29.4 (95 percent confidence interval, 16.1 to 53.6) for days 3 through 14 after a first dose. There was also an increase in the risk of intussusception after the second dose of the vaccine, but it was smaller than the increase in risk after the first dose. Assuming full implementation of a national program of vaccination with RRV-TV, we estimated that 1 case of intussusception attributable to the vaccine would occur for every 4670 to 9474 infants vaccinated. CONCLUSIONS: The strong association between vaccination with RRV-TV and intussusception among otherwise healthy infants supports the existence of a causal relation. Rotavirus vaccines with an improved safety profile are urgently needed.

Case-Control Studies↗
PubMed2001

Influence of hemostatic factors on spontaneous abortion.

To assess the relationship between hemostatic factors and spontaneous abortion, 134 pregnant women presenting to the emergency department were recruited and followed through 22 weeks' gestation. Cases were women experiencing a spontaneous abortion and controls were women who maintained their pregnancy. Fibrinogen, factor VII antigen, activated protein C-sensitivity ratio (APC-SR), protein S, and plasmin-antiplasmin (PAP) were measured. Cases had lower mean levels of fibrinogen and factor VII antigen compared with controls (3.1 g/L vs. 3.7 g/L and 89% of normal vs. 109% of normal, respectively). Regression analyses found that women with fibrinogen levels below 3.0 g/L had a five-fold increased risk of spontaneous abortion (OR = 5.1, 95% CI: 1.8-14.4) and women with factor VII antigen levels below 94% of normal had a threefold increased risk of spontaneous abortion normal (OR = 3.3, 95% CI: 1.2-8.5). Similar mean levels of APC-SR, protein S, and PAP were found in the two groups.

Abortion, Spontaneous↗
PubMed2001

Risk factors for post-ERCP pancreatitis: a prospective, multicenter study.

BACKGROUND: Post-ERCP pancreatitis is poorly understood. The goal of this study was to comprehensively evaluate potential procedure- and patient-related risk factors for post-ERCP pancreatitis over a wide spectrum of centers. METHODS: Consecutive ERCP procedures were prospectively studied at 11 centers (6 private, 5 university). Complications were assessed at 30 days by using established consensus criteria. RESULTS: Pancreatitis occurred after 131 (6.7%) of 1963 consecutive ERCP procedures (mild 70, moderate 55, severe 6). By univariate analysis, 23 of 32 investigated variables were significant. Multivariate risk factors with adjusted odds ratios (OR) were prior ERCP-induced pancreatitis (OR 5.4), suspected sphincter of Oddi dysfunction (OR 2.6), female gender (OR 2.5), normal serum bilirubin (OR 1.9), absence of chronic pancreatitis (OR 1.9), biliary sphincter balloon dilation (OR 4.5), difficult cannulation (OR 3.4), pancreatic sphincterotomy (OR 3.1), and 1 or more injections of contrast into the pancreatic duct (OR 2.7). Small bile duct diameter, sphincter of Oddi manometry, biliary sphincterotomy, and lower ERCP case volume were not multivariate risk factors for pancreatitis, although endoscopists performing on average more than 2 ERCPs per week had significantly greater success at bile duct cannulation (96.5% versus 91.5%, p = 0.0001). Combinations of patient characteristics including female gender, normal serum bilirubin, recurrent abdominal pain, and previous post-ERCP pancreatitis placed patients at increasingly higher risk of pancreatitis, regardless of whether ERCP was diagnostic, manometric, or therapeutic. CONCLUSIONS: Patient-related factors are as important as procedure-related factors in determining risk for post-ERCP pancreatitis. These data emphasize the importance of careful patient selection as well as choice of technique in the avoidance of post-ERCP pancreatitis.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed2001

Do clerkship experiences affect medical students' attitudes toward chronically ill patients?

PURPOSE: To measure changes in medical students' attitudes toward chronically ill patients, and to identify experiences, specifically during clerkships, that contributed to students' attitudes. METHOD: A cohort of students from five U.S. medical schools voluntarily participated in three surveys longitudinally administered before and after required clinical rotations. The first two questionnaires were identical and asked for demographic information and pre-matriculation experiences with chronically ill patients. The third was modified to include questions about clinical experiences with chronically ill patients. Responses from the first and third questionnaires were linked for analysis. RESULTS: A total of 502 of 695 students (69%) completed both the first and the third questionnaires. Many students (36%) had had pre-matriculation experiences with chronic illness. After clinical training, 25% of the respondents stated that they would seek another career specialty if the incidence of chronically ill patients increased in their chosen field, compared with the 9% who responded so before clinical training (p <.001). While 73% of the students had favorable perceptions toward chronically ill patients, and 91% felt involved in care, significantly fewer students (p <.01) had had positive patient care experiences when working with residents (57%) and attendings (59%). Gender, age, prior experiences, and school site were not associated with attitudinal changes. CONCLUSION: Students begin medical school with positive attitudes toward caring for chronically ill patients, but this perception depreciates with clinical experience, which may affect specialty decisions. Contributing factors may include adequate role modeling by residents and attendings and a perceived discrepancy in the quality of care patients receive.

Adult↗
PubMed2000

The accuracy of physical examination to detect abdominal aortic aneurysm.

BACKGROUND: Abdominal palpation during physical examination is an important means of detecting abdominal aortic aneurysm (AAA), but limited information is available on its accuracy. METHODS: Two hundred subjects (aged 51-88 years), 99 with and 101 without AAA as determined by previous ultrasound, each underwent physical examination of the abdomen by 2 internists who were blinded to each other's findings and to the ultrasound diagnosis. RESULTS: The overall accuracy of abdominal palpation for detecting AAA was as follows: sensitivity, 68% (95% confidence interval [CI], 60%-76%); specificity, 75% (95% CI, 68%-82%); positive likelihood ratio, 2.7 (95% CI, 2.0-3.6); negative likelihood ratio 0.43 (95% CI, 0.33-0.56). Interobserver pair agreement for AAA vs no AAA between the first and second examinations was 77% (kappa = 0.53). Sensitivity increased with AAA diameter, from 61% for AAAs of 3.0 to 3.9 cm, to 69% for AAAs of 4.0 to 4.9 cm, 72% for AAAs of 4.0 cm or larger, and 82% for AAAs of 5.0 cm or larger. Sensitivity in subjects with an abdominal girth less than 100 cm (40-in waistline) was 91% vs 53% for girth of 100 cm or greater (P<.001). When girth was 100 cm or greater and the aorta was palpable, sensitivity was 82%. When girth was less than 100 cm and the AAA was 5.0 cm or larger, sensitivity was 100% (12 examinations). Factors independently associated with correct examination findings included AAA diameter (odds ratio [OR], 1.95 per centimeter increase; 95% CI, 1.06-3.58); abdominal girth (OR, 0.90 per centimeter increase; 95% CI, 0.87-0.94); and the examiner's assessment that the abdomen was not tight (OR, 2.68; 95% CI, 1.17-6.13). CONCLUSIONS: Abdominal palpation has only moderate overall sensitivity for detecting AAA, but appears to be highly sensitive for diagnosis of AAAs large enough to warrant elective intervention in patients who do not have a large girth. Abdominal palpation has good sensitivity even in patients with a large girth if the aorta is palpable.

Abdomen↗
PubMed2000

A randomized, controlled trial of transcutaneous carbon dioxide monitoring during ERCP.

BACKGROUND: Pulse oximetry, used to monitor oxygen saturation during endoscopy, does not directly measure hypoventilation. Study goals were to determine whether transcutaneous carbon dioxide (PtcCO(2)) monitoring during endoscopic retrograde cholangiopancreatography (ERCP) prevents severe hypoventilation and to assess the accuracy of clinical observation and pulse oximetry in detecting hypoventilation. METHODS: All patients received intensive clinical and electronic monitoring including pulse oximetry. Supplemental oxygen was administered for pulse oximetry < 90%. Patients were randomized to a treatment arm (group 1) where PtcCO(2) monitoring guided sedation or a control arm (group 2) where PtcCO(2) was recorded but unavailable for guiding sedation. RESULTS: Group 1 had significantly fewer episodes of severe carbon dioxide retention (rise in PtcCO(2) >/=40 mm Hg above baseline) than group 2 (0 of 199 versus 5 of 196, respectively, p = 0.03), as well a shorter mean duration of procedure discomfort (8.3% of procedure duration rated as "uncomfortable" versus 11.5%, p = 0.04). Correlations between clinical observation and objective measures of ventilation were poor: level of sedation versus PtcCO(2) (R = 0.3) or pulse oximetry (R = 0.06); slowest respiratory rate versus PtcCO(2) (R = 0.4) or pulse oximetry (R = -0.4). PtcCO(2) rises of greater than 20 mm Hg occurred without oxygen desaturation in 10.7% of patients receiving supplemental oxygen. CONCLUSIONS: Carbon dioxide retention during ERCP is not reliably detected by clinical observation or by pulse oximetry in patients receiving supplemental oxygen. The addition of PtcCO(2) monitoring prevents severe carbon dioxide retention more effectively than intensive clinical monitoring and pulse oximetry alone. The clinical relevancy of this observation needs to be determined in an appropriately designed outcome study.

Blood Gas Monitoring, Transcutaneous↗