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Biomedical subjects

Matthew Thompson

Publications and source records attributed to Matthew Thompson.

7 recordsLinked to original sources
PubMed2006

Effects of cell saver autologous blood transfusion on blood loss and homologous blood transfusion requirements in patients undergoing cardiac surgery on- versus off-cardiopulmonary bypass: a randomised trial.

OBJECTIVE: Off-pump CABG is potentially associated with reduced intraoperative blood loss and homologous blood transfusion in comparison to on-pump CABG. In this randomised controlled study we investigated the effects of autologous cell saver blood transfusion on blood loss and homologous blood transfusion requirements in patients undergoing CABG on- versus off-CPB. METHODS: Eighty patients were randomised into one of four groups: (A) on-CPB with cell saver blood transfusion (CSBT), (B) on-CPB without CSBT, (C) off-pump with CSBT and (D) off-pump without CSBT. Volume of intraoperative autologous blood transfusion, postoperative mediastinal blood loss and homologous blood transfusion requirements were measured. Homologous blood was transfused when haemoglobin concentration fell below 8 g/dl postoperatively. Pre- and postoperatively prothrombin time and partial thromboplastin time were measured. RESULTS: Preoperative patient characteristics were well matched among the four groups. The amount of salvaged mediastinal blood available for autologous transfusion was significantly higher in the on-pump group (A) compared to the off-CPB group (C) (433+/-155 ml vs 271+/-144 ml, P=0.001). Volume of homologous blood transfusion was significantly higher in group B vs groups A, C and D (595+/-438 ml vs 179+/-214, 141+/-183 and 230+/-240 ml, respectively, P<0.005). The cell saver groups (A and C) received significantly less homologous blood than the groups without cell saver (160+/-197 ml vs 413+/-394 ml, respectively, P<0.005). Patients undergoing off-CPB surgery received significantly less homologous blood than those undergoing on-CPB CABG irrespective of cell saver blood transfusion (184+/-214 ml vs 382+/-397 ml, P<0.05). Postoperative blood loss was similar in the four groups (842+/-276, 1023+/-291, 869+/-286 and 903+/-315 ml in groups A to D, respectively, P>0.05). Clotting test results revealed no significant difference between the groups. There was no significant difference in postoperative morbidity between groups. CONCLUSION: Off-pump CABG is associated with significant reduction in intraoperative mediastinal blood loss and homologous transfusion requirements. Autologous transfusion of salvaged washed mediastinal blood reduced homologous transfusion significantly in the on-CPB group. Cell saver caused no significant adverse impact on coagulation parameters in on- or off-CPB CABG. Postoperative morbidity and blood loss were not affected by the use of CPB or autologous blood transfusion. We recommend the use of autologous blood transfusion in both on- and off-pump CABG surgery.

Aged↗
PubMed2006

Parenteral penicillin for children with meningococcal disease before hospital admission: case-control study.

OBJECTIVE: To explore the impact on mortality and morbidity of parenteral penicillin given to children before admission to hospital with suspected meningococcal disease. DESIGN: Retrospective comparison of fatal and non-fatal cases. SETTING: England, Wales, and Northern Ireland; December 1997 to February 1999. PARTICIPANTS: 158 children aged 0-16 years (26 died, 132 survived) in whom a general practitioner had made the diagnosis of meningococcal disease before hospital admission. RESULTS: Administration of parenteral penicillin by general practitioners was associated with increased odds ratios for death (7.4, 95% confidence interval 1.5 to 37.7) and complications in survivors (5.0, 1.7 to 15.0). Children who received penicillin had more severe disease on admission (median Glasgow meningococcal septicaemia prognostic score (GMSPS) 6.5 v 4.0, P = 0.002). Severity on admission did not differ significantly with time taken to reach hospital. CONCLUSIONS: Children who were given parenteral penicillin by a general practitioner had more severe disease on reaching hospital than those who were not given penicillin before admission. The association with poor outcome may be because children who are more severely ill are being given penicillin before admission.

Adolescent↗
PubMed2005

Timing of follow-up voiding cystourethrogram in children with primary vesicoureteral reflux: development and application of a clinical algorithm.

BACKGROUND AND OBJECTIVES: Of children diagnosed with urinary tract infection, 30% to 40% have primary vesicoureteral reflux (VUR). For the majority of these children, treatment involves long-term prophylactic antibiotics (ABX) and a periodic voiding cystourethrogram (VCUG) until resolution of VUR as detected by VCUG. Radiation exposure and considerable discomfort have been associated with VCUG. To date, no clear guidelines exist regarding the timing of follow-up VCUGs. The objective of this study was to develop a clinically applicable algorithm for the optimal timing of repeat VCUGs and validate this algorithm in a retrospective cohort of children with VUR. METHODS: Based on previously published data regarding the probability of resolution of VUR over time, a decision-tree model (DTM) was developed. The DTM compared the differential impact of 3 timing schedules of VCUGs (yearly, every 2 years, and every 3 years) on the average numbers of VCUGs performed, years of ABX exposure, and overall costs. Based on the DTM, an algorithm optimizing the timing of VCUG was developed. The algorithm then was validated in a retrospective cohort of patients at an urban pediatric referral center. Data were extracted from the medical records regarding number of VCUGs, time of ABX prophylaxis, and complications associated with either. VUR in patients in the cohort was grouped into mild VUR (grades I and II and unilateral grade III for those < or =2 years old), and moderate/severe VUR (other grade III and grade IV). Kaplan-Meier survival curves were created from the cohort data. From the survival curves, the median times to resolution of VUR were determined for the cohort, and these times were compared with the median times to VUR resolution of the data used for the DTM. The numbers of VCUGs performed, time of ABX exposure, and costs in the cohort were compared with those that would have occurred if the algorithm had been applied to both mild and moderate/severe VUR groups. RESULTS: Using an algorithm that results in a recommendation of VCUGs every 2 years in mild VUR would reduce the average number of VCUGs by 42% and costs by 33%, with an increase in ABX exposure of 16%, compared with a schedule of yearly VCUGs. For moderate/severe VUR, a VCUG performed every 3 years would reduce the average number of VCUGs by 63% and costs by 51%, with an increase in ABX exposure of 10%. Applying this algorithm to the retrospective cohort consisting of 76 patients (between 1 month and 10 years old) with primary VUR would have reduced overall VCUGs by 19% and costs by 6%, with an increase in ABX exposure of 26%. The patterns of VUR resolution, age distribution, and prevalence of severity of VUR were comparable between previously published results and the retrospective cohort. CONCLUSIONS: Delaying the schedule of VCUG from yearly to every 2 years in children with mild VUR and every 3 years in children with moderate/severe VUR yields substantial reductions in the average numbers of VCUGs and costs, with a modest subsequent increase in ABX exposure.

Algorithms↗
PubMed2004

Time resolved solvent rearrangement dynamics.

Ultrafast pump-probe studies of I2- recombination in size-selected I2- (CO2)n cluster ions demonstrate long time coherent motions in size-selected clusters and the resulting non-statistical energy flow in the cluster. For I2- photodissociated to produce either I- + I or I- + I*, we identify a solvent-driven energy transfer process without a condensed phase counterpart. The mechanism involved is a Marcus-like solvent-driven curve crossing, with the driving force arising from asymmetric solvation, not just from solvent orientation. By substituting another halogen for one I atom, we "break" the I2- symmetry, and thus obtain direct information on the electron transfer process. New experiments on IBr- (CO2)n photodissociation products confirm the behavior suspected in the I2- studies. Time-resolved experiments on IBr- and theoretical modeling of the dynamics provide quantitative information on the multiple curve crossings encountered in the recombination process. In related investigations, femtosecond negative ion-neutral-positive ion charge reversal apparatus is employed to investigate transient neutral species evolving along a reaction coordinate. We report studies of the rearrangement dynamics of Cu(OH2) produced by photodetachment of the corresponding anion. Following a controlled delay period, a second ultrafast tunable laser pulse initiates resonant multiphoton photoionization of the time-evolving Cu...OH2 complex. The time-resolved Cu+ and Cu+(OH2) signals provide information both on the prompt dissociation of the complex and on energy redistribution between internal rotational and radial modes of the evolving complex. Calculations of the time evolution of the anion geometric configuration on the neutral potential energy surface yield deeper insight into the nature of the rearrangement process and the energy flow within the complex.

Journal Article↗
PubMed2004

To be reassured or to understand? A dilemma in communicating normal cervical screening results.

BACKGROUND: Receiving negative test results may be associated with two problems: (a). not being reassured and wanting further, unnecessary screening; and (b). not understanding residual risk and not attending future recommended screening. AIM: To test two hypotheses: (1). Emphasizing test accuracy and low residual risk when giving negative test results reduces a desire for further unnecessary screening, while also reducing a correct understanding of the meaning of the result. (2). The effect of emphasizing low risk on desire for future screening is mediated by lack of reassurance. DESIGN: Experimental, vignette-based study, with a 2 x 2 factorial design. METHOD: A sample of 184 women was asked to imagine that they had recently undergone a cervical screening test and received a normal result. They were given one of four hypothetical letters from their GP,differing in whether or not it emphasized test accuracy and low residual risk of developing cervical cancer. Participants completed a questionnaire assessing perceived risk, reassurance about test results, desire for further screening within six months and understanding of the test results. RESULTS: Emphasizing test accuracy and low residual risk increases desire for inappropriate screening while reducing the understanding of residual risk. These effects are interactive, in that presenting both together has a larger effect than the sum of the two individual effects. The effect of emphasizing low risk on desire for future screening was mediated by reassurance. CONCLUSION: Emphasizing low residual risk and test accuracy is a double-edged sword: it reduces a desire for unnecessary screening, but also reduces correct understanding of the result.

Adolescent↗