Biomedical subjects

Derek Stephens

Publications and source records attributed to Derek Stephens.

41 records · Page 3Linked to original sources

PubMed2002

Assessment of thrombocytopenic disorders using the Platelet Function Analyzer (PFA-100).

The Platelet Function Analyzer (PFA-100) was used to measure platelet function in paediatric patients with destructive versus underproduction thrombocytopenia. Closure time (CT) and total volume (TV) measurements with standard 150 microm apertures discriminated between patients with similar platelet counts from 30 to 150 x 10(9)/l. However, at platelet counts < 30 x 10(9)/l, a 100-microm aperture (experimental) gave the best assessment of platelet function. TV results could be analysed even when CTs were indeterminate. Further investigations are warranted to more fully understand the relationships among platelet function as measured by the PFA-100 in standard/experimental modes, bleeding and transfusion outcome in thrombocytopenia.

Adolescent↗

PubMed2002

The active movement scale: an evaluative tool for infants with obstetrical brachial plexus palsy.

Newborns with peripheral nerve lesions involving the upper extremity are difficult to evaluate. The reliability of the Active Movement Scale (AMS), a tool for assessing motor function in infants with obstetrical brachial plexus palsy (OBPP), was examined in 2 complementary studies. Part A was an interrater reliability study in which 63 infants younger than 1 year with OBPP were independently evaluated by 2 physical therapists using the AMS. The scores were compared for reliability and controlled for chance agreement by using kappa statistics. Overall kappa analysis of the 15 tested movements showed a moderate strength of score agreement (kappa = 0.51). Quadratic-weighted kappa (kappa(quad)) statistics showed that 8 of the 15 movements tested were in the highest strength of agreement category (kappa(quad) = 0.81-1.00). Five movements showed substantial agreement (kappa(quad) = 0.61-0.80), and 2 movements had moderate agreement (kappa(quad) = 0.41- 0.60). The overall kappa(quad) was 0.89. Part B was a variability study designed to examine the dispersion of scores when infants with OBPP were evaluated with the AMS by multiple raters. Ten pediatric physical therapists with varying degrees of experience using the scale attended a 1(1/2)-hour instructional workshop on administration of the tool for infants with OBPP. A chain-block study design was used to obtain 30 assessments of 10 infants by 10 raters. A 2-way analysis of variance indicated that the variability of scores due to rater factors was low compared with the variability due to patient factors and that variation in scores due to rater experience was minimal. The results of part A indicate that the AMS is a reliable tool for the assessment of infants with OBPP when raters familiar with the scale are compared. The results of part B suggest that, with minimal training, raters with a range of experience using the AMS are able to reliably evaluate infants with upper-extremity paralysis.

Brachial Plexus↗

PubMed2002

Fetal pulmonary artery diameters and their association with lung hypoplasia and postnatal outcome in congenital diaphragmatic hernia.

OBJECTIVE: We hypothesized that fetal branch pulmonary artery (PA) diameters indirectly reflect lung mass and are associated with postnatal outcome in cases of isolated congenital diaphragmatic hernia (CDH). STUDY DESIGN: We retrospectively reviewed echocardiograms of fetuses with CDH, measuring branch PA diameters and other echocardiographic parameters. Antenatal parameters were correlated with postmortem lung weights in 5 fetuses after pregnancy termination. Fetal echocardiographic measures were correlated with outcome variables in 29 live-born infants with CDH to identify antenatal indices associated with postnatal death and respiratory morbidity. RESULTS: Antenatal branch PA size correlated with postmortem lung weights from 5 terminated fetuses (r = 0.87). In 26 cases of left CDH in which the fetus continued to term, the ipsilateral branch PA diameter was significantly smaller than the contralateral branch PA diameter at presentation (P <.001). In these fetuses, a larger contralateral PA diameter was associated with worse postnatal survival (P =.049). Among survivors with left CDH, the main PA z score and the discrepancy between right and left PA diameters correlated positively with duration of supplemental oxygen requirement (P =.019 and P =.022, respectively) and ventilation (P =.036 and P =.012, respectively). Serial antenatal studies in 8 of 10 cases revealed progressive ipsilateral PA hypoplasia. CONCLUSION: Antenatal branch PA size correlates with postmortem lung weight. A larger contralateral PA, and significant branch PA discrepancy and larger main PA diameter, best correlate with postnatal death and respiratory morbidity, respectively. Progressive ipsilateral PA hypoplasia suggests progressive in utero lung hypoplasia in cases of CDH.

Abortion, Induced↗

PubMed2002

Levels of exhaled nitric oxide before and after surgical and transcatheter device closure of atrial septal defects in children.

OBJECTIVES: We have shown that exhaled nitric oxide levels decrease after surgical closure of congenital left-to-right cardiac shunts. It remains unclear whether the change in exhaled nitric oxide levels reflects endothelial injury caused by the use of cardiopulmonary bypass or the decrease in pulmonary blood flow attendant on shunt closure. Transcatheter atrial septal defect closure permits shunt closure without the use of cardiopulmonary bypass. Therefore we compared changes in exhaled nitric oxide levels after surgical and transcatheter device closure of atrial septal defects. METHODS: We enrolled sequentially 30 children undergoing atrial septal defect closure. Fifteen patients (age range, 0.4-16 years; median age, 6.5 years) underwent surgical atrial septal defect closure with cardiopulmonary bypass, and 15 patients (age range, 4-17 years; median age, 8.4 years) had device closure of the atrial septal defect in the catheterization laboratory. We measured nitric oxide levels in end-tidal expiratory gas with a rapid-response chemiluminescent analyzer before and after atrial septal defect closure. RESULTS: After surgical repair of the atrial septal defect, exhaled nitric oxide decreased by 21%, from 10.9 +/- 4.4 to 8.4 +/- 3.3 ppb (P <.005), whereas after transcatheter defect closure, exhaled nitric oxide increased by 23%, from 7.6 +/- 2.6 to 9.3 +/- 3.7 ppb (P <.005). Hemoglobin levels in patients undergoing surgical intervention were significantly lower (P =.0001) postoperatively. CONCLUSIONS: We confirmed that exhaled nitric oxide, despite a fall in hemoglobin, decreases after surgical closure of atrial septal defects. In contrast, exhaled nitric oxide levels increase after transcatheter closure. Exhaled nitric oxide levels may reflect bypass-induced endothelial cell injury and are independent of changes in pulmonary blood flow.

Adolescent↗

PubMedDate not supplied

Treatments for paediatric femoral fractures: a randomised trial.

BACKGROUND: Treatments for femoral fractures in children vary widely and have been investigated only in case series. We did a multicentre randomised trial to compare malunion rates after external fixation and after early application of a hip spica cast for paediatric femoral shaft fractures. METHODS: All children aged 4-10 years with femoral fractures, admitted to four paediatric hospitals, were randomly assigned early application of hip spica or external fixation. The primary outcome was malunion at 2 years after the fracture. Secondary outcomes were scores on the RAND physical function child health questionnaire and the post-hospitalisation behavioural questionnaire, and parents' and children's ratings of overall satisfaction with treatment. Analysis was by intention to treat based on children who reached the 2 year evaluation. FINDINGS: Of 60 children assigned to the hip-spica group, 56 reached the 2-year assessment; of them, six (11%) required other forms of treatment because of unacceptable loss of reduction. Of 48 children assigned external fixation, 45 reached the 2-year assessment; two (4%) had refractures and five (11%) required operative adjustment of the fixator. The rate of malunion was significantly higher in the hip-spica group than in the external-fixator group (25/56 [45%] vs 7/45 [16%]; 95% CI for difference 12-46%; p=0.002). The two groups had similar mean scores for the RAND physical function health questionnaire (0.34 vs 0.45; 95% CI for difference, -0.57 to 0.34; p=0.61), for the post-hospitalisation questionnaire (106.8 vs 106.3; -4.9 to 5.9; p=0.86), and for parents' satisfaction (4.3 vs 4.2; -0.3 to 0.6; p=0.5) and children's ratings of happiness with treatment (6.9 vs 7.7; -2.2 to 0.5; p=0.21). INTERPRETATION: Early application of hip spica has a small role in the treatment of paediatric femoral fractures. Future trials need to compare external fixation with flexible intramedullary nails.

Casts, Surgical↗