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Biomedical subjects

M Meade

Publications and source records attributed to M Meade.

At least 19 recordsLinked to original sources
PubMed2004

Neither baseline tests of molecular hypercoagulability nor D-dimer levels predict deep venous thrombosis in critically ill medical-surgical patients.

OBJECTIVE: Predicting patients who are harboring asymptomatic deep venous thrombosis (DVT), or who are at particular risk of developing DVT, is a desirable clinical goal since prevention or early treatment of DVT might reduce the risk of fatal pulmonary embolism. Thus validation of simple laboratory tests that reliably predict venous thromboembolism (VTE) would be clinically very important. Tests that might be useful for these applications include markers of hypercoagulability (predicting patients at risk of DVT) and D-dimer (predicting which patients may have acute DVT). METHODS: In a prospective cohort study we measured a panel of hypercoagulability markers at the time of ICU admission, and six commercial D-dimer assays were performed serially during the ICU stay in medical-surgical ICU patients who were screened for DVT with biweekly lower limb compression ultrasonography. Ultrasonography was also performed at the time of any clinically suspected DVT events. We matched cases with DVT with controls without DVT for length of stay in the ICU to generate receiver operating characteristics (ROC) curves. RESULTS: One hundred ninety-seven patients were enrolled. Blood was collected on a total of 763 occasions (median number of occasions per patient: 3, range 1-21). None of the assays predicted DVT, as indicated by the areas under the ROC curves, that did not differ significantly from 50%. CONCLUSION: In critically ill patients, neither tests of hypercoagulability nor D-dimer levels predict patients at risk of DVT and thus they should not be used to guide diagnostic testing for DVT.

Aged↗
PubMed2001

Physiological compensation in unilateral eyestalk ablated crayfish, Cherax quadricarinatus.

The eyestalks of crustaceans contain neurosecretory cells involved in the regulation of molting. In crayfish, bilateral ablation results in increased molting frequency and weight gain whereas unilateral ablation typically has no effect on molting frequency and weight gain. The effects of unilateral ablation were examined in juvenile Australian freshwater crayfish, Cherax quadricarinatus. As observed for other crayfish species, molting frequency and weight gain of unilateral ablated crayfish were not significantly different from control (intact) crayfish. Survival of unilateral ablated crayfish, however, was reduced compared to controls and was likely due to stress associated with the surgical procedure itself. Using radiolabeling techniques, protein synthesis was determined for neural tissues from the remaining eyestalk of ablated crayfish and compared to protein synthesis of neural tissues from eyestalks of control, non-ablated crayfish. Protein synthesis of ablated crayfish neural tissues was significantly higher (ca. 45%) than protein synthesis of control neural tissues. Electrophoretic analysis (SDS-PAGE and autoradiography) further demonstrated that protein synthesis increased linearly for all proteins in the remaining eyestalk of ablated crayfish. Together, these results suggest that a compensatory response occurred in unilateral ablated crayfish allowing normal physiological functions, particularly those involved in regulating growth cycles, to be maintained. J. Exp. Zool. 289:184-189, 2001.

Adaptation, Physiological↗
PubMed2001

System youth: a subgroup of substance-abusing homeless adolescents.

PURPOSE: While many youths residing at homeless shelters will return home, many are placed in group or foster homes. Few researchers have examined the experiences of adolescents with a history of these out-of-home placements. This study examined shelter residents and compared the experiences of system and non-system youth. METHODS: Information regarding youths' family functioning, substance use, depression and related problem behaviors was obtained from substance abusing system (n = 62) and non-system (n = 82) adolescents staying at local runaway shelters. RESULTS: System males engaged in significantly more delinquent behaviors than did non-system males and system females. Alcohol and drug problem consequences were positively associated with longevity in the system, while having ever attempted suicide was negatively associated with system longevity. System youth reported: 1) taking more prescribed psychotropic medications 2) experiencing more sexual abuse, and 3) less parental overprotection, as compared to non-system youth. Gender differences were found in which females reported more conflictual problem solving interactions with their parents than did males, as well as more comorbid diagnoses. IMPLICATIONS: Although longitudinal research is needed, findings argue that without intervention efforts targeted at identified problem behaviors, youth are at risk to continue their system involvement into adulthood.

Adolescent↗
PubMed2001

Evidence of diffusion from a targeted HIV/AIDS intervention in the Dominican Republic.

The diffusion potential of a targeted HIV/AIDS intervention that enlisted peer educators to disseminate 'safer sex' messages and condoms among female commercial sex workers and their clients was evaluated in the Dominican Republic. Levels of interurban interaction potential were ascertained that linked the targeted city of La Romana with the proximate cities of San Pedro de Macoris and Guaymate. Weekly service statistics generated over an 8-month period were analysed to establish activity areas for the peer educators. Data were entered and analysed using a geographic information system and interurban linkages were established. Project outcomes were examined via a series of three cross-sectional Knowledge, Attitudes and Practices (KAP) surveys conducted among convenience samples of commercial sex workers at the start of the intervention and at 4 and 8 months. The results attest to a high degree of interconnectivity between the targeted and proximate cities, and a pattern of interurban mobility that links commercial sex workers, clients and establishments in all three cities. The examination of project outcomes revealed statistically significant changes in condom use in the targeted city of La Romana among commercial sex workers, as well as among their counterparts interviewed in the proximate cities of San Pedro de Macoris and Guaymate. These data suggest a diffusion effect. It is concluded that a targeted intervention may influence proximate cities within a relatively compressed period of time. The findings suggest the importance of considering geographic diffusion principles, such as urban hierarchies, regional nodes and transportation linkages, when designing HIV/AIDS prevention efforts. It also has important implications in the selection of control sites when conducting experimental studies of HIV/AIDS interventions.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Predicting success in weaning from mechanical ventilation.

We identified 65 observational studies of weaning predictors that had been reported in 70 publications. After grouping predictors with similar names but different thresholds, the following predictors met our relevance criteria: heterogeneous populations, 51; COPD patients, 21; and cardiovascular ICU patients, 45. Many variables were of no use in predicting the results of weaning. Moreover, few variables had been studied in > 50 patients or had results presented to generate estimates of predictive power. For stepwise reductions in mechanical support, the most promising predictors were a rapid shallow breathing index (RSBI) < 65 breaths/min/L (measured using the ventilator settings that were in effect at the time that the prediction was made) and a pressure time product < 275 cm H2O/L/s. The pooled likelihood ratios (LRs) were 1.1 (95% confidence interval [CI], 0.95 to 1.28) for a respiratory rate [RR] of < 38 breaths/min and 0.32 (95% CI, 0.06 to 1.71) for an RR of > 38 breaths/min, which indicate that an RR of < 38 breaths/min leaves the probability of successful weaning virtually unchanged but that a value of > 38 breaths/min leads to a small reduction in the probability of success in weaning the level of mechanical support. For trials of unassisted breathing, the most promising weaning predictors include the following: RR; RSBI; a product of RSBI and occlusion pressure < 450 cm H2O breaths/min/L; maximal inspiratory pressure (PImax) < 20 cm H2O; and a knowledge-based system for adjusting pressure support. Pooled results for the power of a positive test result for both RR and RSBI were limited (highest LR, 2.23), while the power of a negative test result was substantial (ie, LR, 0.09 to 0.23). Summary data suggest a similar predictive power for RR and RSBI. In the prediction of successful extubation, an RR of < 38 breaths/min (sensitivity, 88%; specificity, 47%), an RSBI < 100 or 105 breaths/min/L (sensitivity, 65 to 96%; specificity, 0 to 73%), PImax, and APACHE (acute physiology and chronic health evaluation) II scores that are obtained at hospital admission appear to be the most promising. After pooling, two variables appeared to have some value. An RR of > 38 breaths/min and an RSBI of > 100 breaths/min/L appear to reduce the probability of successful extubation, and PImax < 0.3, for which the pooled LR is 2.23 (95% CI, 1.15 to 4.34), appears to marginally increase the likelihood of successful extubation. Judging by areas under the receiver operator curve for all variables, none of these variables demonstrate more than modest accuracy in predicting weaning outcome. Why do most of these tests perform so poorly? The likely explanation is that clinicians have already considered the results when they choose patients for trials of weaning.

APACHE↗
PubMed2001

Trials comparing alternative weaning modes and discontinuation assessments.

We identified 16 randomized controlled trials (RCTs) of methods for weaning patients from mechanical ventilation, 8 of which were trials of discontinuation assessment strategies, 5 of which were trials of stepwise reduction in mechanical ventilatory support, and 3 of which were trials comparing alternative ventilation modes for weaning periods lasting < 48 h. We found that different thresholds for deciding when a patient is ready for a trial of spontaneous breathing, different criteria for a successful trial, and different thresholds for extubation may overwhelm the impact of alternative ventilation strategies. Nevertheless, the results of these studies suggest the possibility that multiple daily T-piece weaning or pressure support may be superior to synchronized intermittent mandatory ventilation. Other RCTs suggest that early extubation with the back-up institution of noninvasive positive-pressure ventilation as needed may be a useful strategy in selected patients.

Evidence-Based Medicine↗
PubMed2001

Trials of miscellaneous interventions to wean from mechanical ventilation.

We found eight randomized controlled trials (RCTs) of miscellaneous interventions that were designed to facilitate the process of weaning from mechanical ventilation. The two RCTs of high-fat/low-carbohydrate enteral nutrition found favorable physiologic effects on CO2 production and respiratory quotient, rendering this type of nutrition potentially useful in patients with impaired ventilatory reserve; however, no conclusions can be made about the outcomes of the duration of ventilation and weaning success. The two RCTs of postextubation use of noninvasive ventilation are conflicting, showing potential short-term physiologic benefit in one study, but no benefit in terms of reintubation rates or other morbidity. These RCTs are less promising than other applications of noninvasive ventilation such as those in patients with COPD exacerbations. One RCT showed no improvement in success of weaning with exogenous growth hormone administration. In the setting of very frequent baseline blood gas analyses, one RCT of oximetry and capnography was associated with significantly fewer blood gas analyses. Biofeedback to enhance safe and rapid weaning showed a dramatically lower duration of ventilation in one RCT that did not report the weaning methods used. One RCT of preextubation acupuncture showed lower rates of laryngospasm in the acupuncture group. Overall, these studies were underpowered for clinically important outcomes. Multidisciplinary, patient-centered, holistic, and non-pulmonary approaches to weaning may provide additional safe, effective adjunctive methods of hastening liberation from mechanical ventilation.

Acupuncture↗
PubMed2000

Using and understanding sedation scoring systems: a systematic review.

OBJECTIVE: To systematically review instruments for measuring the level and effectiveness of sedation in adult and pediatric ICU patients. STUDY IDENTIFICATION: We searched MEDLINE, EMBASE, the Cochrane Library and reference lists of the relevant articles. We selected studies if the sedation instrument reported items related to consciousness and one or more additional items related to the effectiveness or side effects of sedation. DATA ABSTRACTION: We extracted data on the description of the instrument and on their measurement properties (internal consistency, reliability, validity and responsiveness). RESULTS: We identified 25 studies describing relevant sedation instruments. In addition to the level of consciousness, agitation and synchrony with the ventilator were the most frequently assessed aspects of sedation. Among the 25 instruments, one developed in pediatric ICU patients (the Comfort Scale), and 3 developed in adult ICU patients (the Ramsay scale, the Sedation-Agitation-Scale and the Motor Activity Assessment Scale), were tested for both reliability and validity. None of these instruments were tested for their ability to detect change in sedation status over time (responsiveness). CONCLUSION: Many instruments have been used to measure sedation effectiveness in ICU patients. However, few of them exhibit satisfactory clinimetric properties. To help clinicians assess sedation at the bedside, to aid readers critically appraise the growing number of sedation studies in the ICU literature, and to inform the design of future investigations, additional information about the measurement properties of sedation effectiveness instruments is needed.

Adult↗
PubMed2000

Bleak and hopeless no more. Engagement Of reluctant substance-abusing runaway youth and their families.

Runaway/homeless shelters document high levels of substance abuse among runaway youth, at least double that of school youth. These youth present a constellation of problems and research suggests that this population may be unique in the range and intensity of associated problems. Most studies to date have collected self-report data on these youth; virtually no research has examined treatment effectiveness with the population. Given the void of treatment outcome research with these youths, there is need for identifying potent interventions. Given that issues of engagement and retention must assume prominence in the development of new treatments, this article presents a family-based treatment engagement strategy successfully employed with a sample of substance-abusing youth staying in a southwestern shelter. Youth and primary caretakers are engaged separately by the therapist utilizing motivating factors appropriate to context of the families' lives and to the developmental position of the client.

Adolescent↗
PubMed2000

Venous thromboembolic disease: an observational study in medical-surgical intensive care unit patients.

PURPOSE: Acute and chronic illness, immobility, and procedural and pharmacologic interventions may predispose patients in the intensive care unit (ICU) to venous thromboembolic (VTE) disease. The purpose of this study was to observe potential risk factors and diagnostic tests for VTE, and prophylaxis against VTE in medical-surgical ICU patients. MATERIALS AND METHODS: In a prospective observational study, 93 consecutive patients admitted to a mixed medical-surgical ICU were followed. We recorded demographics, admitting diagnoses, APACHE II score, VTE risk factors, antithrombotic, anticoagulant and thrombolytic agents, diagnostic tests for deep venous thrombosis (DVT) and pulmonary embolus (PE), and clinical outcomes. RESULTS: Patients were 65.5 (15.5) years old with an APACHE II score of 21.1 (9.0); 44 (47.3%) were female. Admission diagnoses were medical (58, 67.4%) and surgical (35, 37.6%). The duration of ICU stay was 3 days (interquartile range: 1, 8.5 days) and the ICU mortality rate was 20.4% (19 of 93). We observed 8 VTE events among 5 of 93 patients (incidence 5.4% [0.8 to 10.0]); 2 patients had DVT and PE before admission, 1 had DVT as an admitting diagnosis, 1 had DVT on day 2 and PE on day 3, and 1 had PE on day 2. Over 804 ICU patient-days, 2 of 5 ultrasound examinations diagnosed DVT and 2 of 3 ventilation-perfusion lung scans diagnosed PE. Of 64 patients in whom heparin was not contraindicated and who were not anticoagulated, subcutaneous heparin prophylaxis was prescribed for 40 (62.5%) patients. ICU-acquired VTE risk factors were mechanical ventilation (odds ratio [OR] 1.56), immobility (OR 2.14), femoral venous catheter (OR 2.24), sedatives (OR 1.52), and paralytic drugs (OR 4.81), whereas VTE heparin prophylaxis (OR 0.08), aspirin (OR 0.42), and thromboembolic disease stockings (OR 0.63) were associated with a lower risk. Only warfarin (OR 0.07, P =.01) and intravenous heparin (OR 0.04, P<.01) were associated with a significantly decreased risk of VTE. CONCLUSIONS: Several ICU-acquired risk factors for VTE were documented in this medical-surgical ICU. VTE prophylaxis was underprescribed, and VTE diagnostic tests were infrequent. Further research is required to determine the incidence, predisposing factors, attributable morbidity, mortality, and costs of VTE in medical-surgical ICU patients, the optimal diagnostic test strategies, and the most cost-effective approaches of prophylaxis.

APACHE↗
PubMed1998

Adjudicating ventilator-associated pneumonia in a randomized trial of critically ill patients.

PURPOSE: The purpose of this study was to evaluate an adjudication strategy for diagnosing ventilator-associated pneumonia (VAP) in a randomized trial. MATERIALS AND METHODS: In a double-blind trial of sucralfate versus ranitidine, one of four pairs of adjudicators examined each case of clinically suspected VAP. Nurse and physician notes and all relevant laboratory data were allocated to each adjudication pair in groups of five patients. Each reader in the pair decided whether the patient had VAP; differences were resolved by consensus discussion. RESULTS: The overall unadjusted study odds ratio for VAP was 0.82 (P = .21) representing a trend toward less pneumonia with sucralfate compared with ranitidine. The odds ratio adjusted for adjudication pair was 0.85 (P = .27). The proportion of charts adjudicated as VAP positive among pairs ranged from 50% to 92%; crude agreement between readers in each pair varied from 50% to 82%. When adjudicators disagreed, the final consensus was split evenly between the two adjudicators' initial opinions in two pairs; in the other two pairs, the final decision reflected one dominant initial opinion. Personnel time to adjudicate all patients with a suspicion of VAP was 74 days. CONCLUSIONS: Though adjudication of outcomes such as VAP is time-consuming, consistent decision-making requires strict criteria, training, and calibration. Patients should be assigned to adjudication teams through random allocation.

Anti-Ulcer Agents↗
PubMed1998

Frequency and methodologic rigor of quality-of-life assessments in the critical care literature.

OBJECTIVES: To present a framework for describing/measuring quality of life (QOL) and health-related quality of life (HRQL), and to assess the frequency and methodologic rigor of QOL studies in the adult critical care literature. DATA SOURCES: Computerized bibliographic search of published research, manual search of key intensive care unit (ICU) journals, and citation review of relevant articles. STUDY SELECTION: We manually searched Critical Care Medicine, American Journal of Respiratory and Critical Care Medicine, and Intensive Care Medicine for the period January 1992 to July 1995 to assess the frequency of published QOL studies. Combined with a computerized bibliographic search, we found 64 studies that met our criteria that reported on patient-related outcomes (other than mortality) after hospital discharge. DATA EXTRACTION: We abstracted data on the nature of each study, the instruments used to measure QOL, and the methodologic rigor of the QOL assessments. We evaluated each study using criteria we developed to assess the validity of HRQL measurements. MEASUREMENTS AND MAIN RESULTS: In our manual search, we found 1,073 articles relevant to the practice of adult critical care. Of these, 19 (1.7%)/1073 included QOL measurements. Combined with our comprehensive search strategy, we found 64 papers that evaluated QOL in ICU patients. These papers dealt primarily with issues of: prognosis (32 [50%]), resource allocation (23 [36%]), and clinical prediction (9 [14%]). We found no randomized trials that included post-ICU QOL as an outcome. With respect to the validity of the HRQL assessments, 63/64 (98%) studies evaluated aspects of patients' lives that we considered important. Thirty-three (52%) studies were limited in scope to specific aspects of HRQL, and 31 (48%) studies covered broad areas of HRQL. In these 64 studies, there were 108 different instruments used. The reliability and validity of the instruments used were reported in 7 (6%) and 15 (14%) cases, respectively. For 81 (75%) instruments, the investigators either explained the results or used informative, qualitative descriptors whose interpretation was self-evident. Overall, three (5%) of the included studies met all four methodologic criteria to assess the validity of HRQL assessments. CONCLUSIONS: QOL assessments occur infrequently in the ICU literature and are of limited methodologic quality. More studies using valid and reliable instruments are necessary to document the long-term QOL of critically ill patients, especially those at risk of a "poor" outcome.

Adult↗
PubMed1985

Carcinogenic responses to chemicals applied directly to rat mammary glands in situ.

In four experiments, concentrated glycerin suspensions of 7,12-dimethylbenz[a]anthracene (DMBA), or the water-soluble compounds, N-methyl-N-nitrosourea (MNU), N-ethyl-N-nitrosourea (ENU), and 4-nitroquinoline-N-oxide (4-NQO) were delivered into pockets in the mammary fat pads in female Sprague-Dawley rats. In a 90-day experiment, each of three groups of 20-22 rats were treated with either 25, 50 or 100 micrograms DMBA delivered to each of four sites in each rat per group. Dose-related responses were detected for incidence of rats with mammary adenocarcinoma (MAC), and for number of MAC per treated site. In a 120-day study, each of three groups of 20 animals were treated with either 250, 500 or 1000 micrograms MNU at each of 80 sites per group. Dose-related MAC responses were detected for incidence of rats with MAC, number of MAC per treated site, and time to detection of MAC. In two experiments of 90 days duration, groups of 20 females were treated with either 1000 micrograms ENU or 1000 micrograms 4-NQO at each of 80 sites per group. ENU produced a total of 27 MAC sites in 65% of the rats, and 4-NQO produced a total of 26 MAC in 60% of the rats. A comparison of the time to detection of all MAC data for the three water-soluble compounds at the 1000 micrograms treatment level, or on the basis of moles per treatment, yielded a carcinogenic potency relationship of 4-NQO greater than ENU greater than MNU.

4-Nitroquinoline-1-oxide↗