Biomedical subjects

David Zurakowski

Publications and source records attributed to David Zurakowski.

At least 37 records · Page 2Linked to original sources

PubMed2006

Interrater reliability in assessing quality of diagnostic accuracy studies using the QUADAS tool. A preliminary assessment.

RATIONALE AND OBJECTIVES: Quality Assessment of Diagnostic Accuracy Studies (QUADAS) is a new tool to measure the methodological quality of diagnostic accuracy studies in systematic reviews. We used data from a systematic review of magnetic resonance spectroscopy (MRS) in the characterization of suspected brain tumors to provide a preliminary evaluation of the inter-rater reliability of QUADAS. MATERIALS AND METHODS: A structured literature search identified 19 diagnostic accuracy studies. These publications were distributed randomly to primary and secondary reviewers for dual independent assessment. Reviewers recorded methodological quality by using QUADAS on a custom-designed spreadsheet. We calculated correlation, percentage of agreement, and kappa statistic to assess inter-rater reliability. RESULTS: Most studies in our review were judged to have used an accurate reference standard. Conversely, the MRS literature frequently failed to specify the length of time between index and reference tests or that the clinicians were unaware of the index test findings when reporting the reference standard. There was good correlation (rho = 0.78) between reviewers in assessment of the overall number of quality criteria met. However, mean agreement for individual QUADAS questions was only fair (kappa = 0.22) and ranged from no agreement beyond chance (kappa < 0) to moderate agreement (kappa = 0.58). CONCLUSION: Inter-rater reliability in our study was relatively low. Nevertheless, we believe that QUADAS potentially is a useful tool for highlighting the strengths and weaknesses of existing diagnostic accuracy studies. Low reliability suggests that different reviewers will reach different conclusions if QUADAS is used to exclude "low-quality" articles from meta-analyses. We discuss methods for improving the validity and reliability of QUADAS.

Brain Neoplasms↗

PubMed2006

Comparative flexion after rotating-platform vs fixed-bearing total knee arthroplasty.

A retrospective review of rotating-platform (n = 113) and fixed-bearing (n = 100) total knee arthroplasties at a minimum 2-year follow-up was performed. All patients in both groups in this study had osteoarthritis and underwent surgery by 1 of the 2 senior authors at 1 of 2 institutions. A cruciate-retaining total knee arthroplasty was implanted with patellar resurfacing in all cases. The only difference between the 2 groups was the design of the tibial bearing and its tibial tray. Through minimization of confounding variables relating to pathology, surgeon, institution, soft-tissue balancing, and type of prosthesis, this study isolates articular design as a variable. We could not demonstrate any significant difference in knee flexion after either fixed-bearing or rotating-platform cruciate-retaining total knee arthroplasty.

Aged↗

PubMed2006

Cerebral endothelial nitric oxide synthase expression is reduced after very-low-flow bypass.

BACKGROUND: In previous studies we have shown that delayed capillary reperfusion after low flow bypass predicts neurologic injury. In this acute study, we hypothesized that low flow reduces endothelial nitric oxide synthase (eNOS) expression, which may lead to more profound inflammatory response and delayed capillary perfusion. METHODS: Twelve piglets (13.2 +/- 0.7 kg) had a cranial window placed over the parietal cerebral cortex for direct examination of the microcirculation using intravital fluorescence microscopy. Animals were cooled to 15 degrees C or 34 degrees C on cardiopulmonary bypass (pH stat, hematocrit 30%, pump flow 100 mL/kg/minute) followed by 2 hours of low flow (50 mL/kg/minute) or very low flow (10 mL/kg/minute). Rhodamine staining was used to observe adherent and rolling leukocytes in postcapillary venules. The eNOS protein expression was determined by Western immunoblotting. RESULTS: High temperature and low flow rate correlated with significantly reduced eNOS expression (p < 0.01). Univariate comparisons based on Student t tests indicated that eNOS protein levels were lower at 34 degrees C than at 15 degrees C (0.7 +/- 0.6 vs 1.7 +/- 0.5, p < 0.01) and at 10 mL/kg per minute compared with 50 mL/kg per minute (0.8 +/- 0.7 vs 1.6 +/- 0.5, p = 0.03). Moreover, two-way analysis of variance revealed that temperature (F = 21.6, p < 0.001) and flow rate (F = 13.8, p = 0.005) were independent multivariate predictors of eNOS expression. During low flow bypass, eNOS was inversely correlated with numbers of adherent (p = 0.002) and rolling (p = 0.006) leukocytes, following an exponential decay curve closely. CONCLUSIONS: eNOS expression is reduced after very low flow bypass, particularly at a higher bypass temperature. This is associated with delayed capillary reperfusion. Reduced eNOS is also associated with increased white cell activation which may lead to greater neurologic injury.

Animals↗

PubMed2006

Analysis of surgical outcome in complex double-outlet right ventricle with heterotaxy syndrome or complete atrioventricular canal defect.

BACKGROUND: Double-outlet right ventricle encompasses a broad spectrum of anomalies. Heterotaxy syndrome, which is often associated with total anomalous pulmonary venous connection and complete atrioventricular canal defect, has been considered a risk factor for surgical repair of double-outlet right ventricle. METHODS: From January 1992 to May 1999, medical records of 96 patients (50 males, 46 females) who had complex double-outlet right ventricle with heterotaxy and/or complete atrioventricular canal defect were reviewed (median age at initial surgery 3 months). Seventeen patients were neonates requiring surgery. Follow-up ranged from 1 day to 7.4 years (median, 16 months). RESULTS: Sixty-eight patients had heterotaxy syndrome (27 with total anomalous pulmonary venous connection). Eighty-three had complete atrioventricular canal defect, 22 with moderate to severe atrioventricular valve regurgitation at the time of surgical repair. Eight patients had two-ventricle repair, and 88 patients were considered for single-ventricle management (bidirectional Glenn, 37; Fontan, 44). One patient had heart transplantation after bidirectional Glenn. There were 16 deaths including 10 early (<30 days postoperatively). Overall survival (95% confidence interval) estimated by the Kaplan-Meier method was 89% (83% to 96%) at 1 month, 84% (76% to 91%) at 1 year, and 81% (73% to 89%) at 5 years. Multivariate analysis revealed that neonatal presentation requiring surgery (p < 0.0001), moderate to severe atrioventricular valve regurgitation (p = 0.03), and pulmonary venous obstruction (p = 0.02) were risk factors for death. CONCLUSIONS: Atrioventricular valve regurgitation, pulmonary venous obstruction, and neonatal presentation are risk factors for mortality in patients with complex double-outlet right ventricle. Early surgical intervention in symptomatic neonates and infants, including those with pulmonary venous obstruction, may reduce mortality and improve outcome after staged operation.

Abnormalities, Multiple↗

PubMed2006

Dopamine induces postischemic cardiomyocyte apoptosis in vivo: an effect ameliorated by propofol.

BACKGROUND: Dopamine is commonly used to improve postischemic myocardial contractile function. However, there is evidence that dopamine augments apoptosis after ischemia through increased intracellular calcium and opening of the mitochondrial permeability transition pore. Propofol (2,6-diisopropylphenol) is an anesthetic that has been shown to prevent mitochondrial permeability transition pore opening. We evaluated the effects of propofol given during reperfusion on dopamine-mediated apoptosis. METHODS: Hearts from 8-week-old inbred New Zealand White rabbit siblings were subjected to 2 hours of cold cardioplegic ischemia and 6 hours of reperfusion in a heterotopic transplant model. Controls consisted of the recipient rabbit's nonischemic heart. The ischemia-reperfusion (IR) group consisted of postischemic hearts reperfused with no drugs; the IR plus dopamine (IR+D) group received dopamine (20 microg x kg(-1) x min(-1)) continuously; the IR+D plus propofol (IR+D+P) group received dopamine (20 microg x kg(-1) x min(-1)) plus propofol (500 to 600 microg x kg(-1) x min(-1)); and the IR plus propofol (IR+P) group received propofol only (500 to 600 microg x kg(-1) x min(-1)) throughout reperfusion (n = 7 to 9 in each group). Myocardial function was measured using a left ventricular balloon; terminal nick-end labeling (TUNEL) staining, DNA electrophoresis, and immunoblotting for caspase-3 cleavage were performed at the end of reperfusion. RESULTS: Dopamine increased the number of TUNEL-positive nuclei significantly (14.0 +/- 2.0/1,000 for IR+D versus 6.7 +/- 2.0/1,000 for IR, p = 0.01). Propofol (IR+D+P) reduced the total number of apoptotic cells in hearts receiving dopamine (7.1 +/- 1.8/1,000, p = 0.01 versus IR+D) to the extent seen in IR alone. DNA laddering and caspase-3 cleavage were observed at greater frequency in the IR+D group compared with the IR and IR+D+P groups. Propofol had no effect on dopamine-mediated increased systolic function, but improved diastolic function after ischemia. CONCLUSIONS: Dopamine infusion has a positive inotropic effect on the postischemic heart at the expense of increased cardiomyocyte apoptosis. The addition of propofol prevents dopamine-induced apoptosis after ischemia while maintaining positive inotropy.

Anesthetics, Intravenous↗

PubMed2006

Reference points for radial head prosthesis size.

PURPOSE: Metallic radial head implants are useful when the radial head cannot be repaired reliably and when either the elbow or the forearm is unstable. Problems arise when the radial head prosthesis is too thick, causing erosions of the capitellum and incongruity of the ulnohumeral joint. We used quantitative 3-dimensional computed tomography analysis to investigate the relative height of the radial head relative to the lateral edge and central ridge of the coronoid process as reference points for optimal insertion of a radial head prosthesis. METHODS: Seventeen computed tomography scans of the elbow were analyzed. The anatomic coronal plane of the forearm was determined using 3-dimensional images and a 2-dimensional image bisecting the articular surface of the radial head was created in this plane. The distance between the plane of the articular surface of the radial head and parallel planes at the most proximal aspect of the coronoid (the central ridge) and the lateral edge of the coronoid articular surface were measured. Negative values indicate the radial head is proximal to the coronoid. RESULTS: The average distance between the planes defined by the radial head articular surface and the coronoid central ridge was -0.8 mm. The average distance between the planes defined by the radial head articular surface and the lateral edge of the coronoid articular surface was -0.9 mm. CONCLUSIONS: Because the radial head was on average only 0.9 mm more proximal than the lateral edge of the coronoid process and because the key is to not overstuff the joint a useful general guideline would be to place the plane of the articular surface of the radial head even with or just slightly more proximal than the lateral edge of the coronoid articular surface. Considering the substantial variability of the normal height of the articular surface of the radial head with respect to that of the coronoid, preoperative radiographs of the opposite elbow may be useful to avoid overstuffing the elbow.

Adolescent↗

PubMed2006

Low-profile dorsal plating for dorsally angulated distal radius fractures: an outcomes study.

PURPOSE: Controversy exists surrounding the effectiveness and complications associated with dorsal plating for distal radius fractures. This study evaluated the functional outcome of dorsal plating for dorsally angulated distal radius fractures at a single institution. METHODS: Thirty patients formed the study cohort. All plates were low profile and stainless steel. Radiographic parameters, range of motion, and strength compared with the uninjured side were recorded. The functional outcome was evaluated by the Disabilities of the Arm, Shoulder, and Hand questionnaire and the Gartland and Werley scoring system. RESULTS: The median patient age at surgery was 59 years. The median follow-up period was 18 months. According to the AO classification system, there were 4 type A fractures, 5 type B fractures, and 21 type C fractures. The median preoperative dorsal angulation was 30 degrees, and the median postoperative angulation was -4 degrees volar. Sixteen patients with fractures had an intra-articular step-off or gap, which were all corrected to neutral by the procedure. Seven patients with the fractures showed positive ulnar variance, all corrected to neutral at time of follow-up evaluation. Compared with the contralateral side, the mean extension and flexion were 88% and 81%, respectively; pronation and supination were 89% and 87%, respectively; and grip strength and thumb pinch were 78% and 94%, respectively. The mean postoperative Disabilities of the Arm, Shoulder, and Hand questionnaire score was 15 points, and 28 patients had Gartland and Werley scores of good or excellent. No patients needed to have their plates removed, and no extensor tendon rupture was reported. One patient lost reduction, 1 patient needed a tenolysis of the extensor pollicis longus tendon, and 2 patients required the removal of a single metaphyseal screw. CONCLUSIONS: Results from this study show that patients can expect to have 80% of their range of motion and strength after dorsal plating for distal radius fractures. Moreover, 93% of the patients will have good to excellent functional outcomes. Complications from dorsal plating may be caused by the specific plate used, rather than by the technique itself, supporting a dorsal approach for dorsally angulated distal radius fractures.

Adult↗

PubMed2006

Elbow capsulectomy for posttraumatic elbow stiffness.

PURPOSE: To determine factors associated with diminished elbow function and upper-extremity-specific health status after elbow capsulectomy for posttraumatic stiffness. METHODS: Forty-six adult patients with posttraumatic elbow stiffness were evaluated an average of 48 months after open capsular excision. A second capsular excision was performed in 9 patients (29%). Stepwise multiple linear regression analysis was used to identify predictors of the American Shoulder and Elbow Surgeons Elbow Score, the Mayo Elbow Performance Index, and the Disabilities of the Arm, Shoulder, and Hand scores after all procedures. RESULTS: The average improvement in ulnohumeral motion after the index surgery for capsular release was 53 degrees . (The average flexion was 98 degrees .) The 9 patients who had subsequent repeat elbow contracture release gained an additional 24 degrees , leading to a final average flexion arc for the entire cohort of 103 degrees . Multiple linear regression identified the American Shoulder and Elbow Surgeons pain score, persistent ulnar nerve dysfunction, and duration of follow-up evaluation after the initial capsular release as independent predictors of a higher Disabilities of the Arm, Shoulder, and Hand questionnaire score; flexion arc and pain score as independent predictors of the Mayo Elbow Performance Index; and flexion arc, forearm arc, pain score, and persistent ulnar neuropathy as independent predictors of the American Shoulder and Elbow Surgeons score. CONCLUSIONS: Open elbow capsulectomy for posttraumatic elbow stiffness restores a near-100 degrees flexion arc on average. Second elbow releases provide limited additional motion in most patients. Final motion influences physician-based rating scales but not patient-specific health status (Disabilities of the Arm, Shoulder, and Hand questionnaire), which is dominated by pain and persistent ulnar neuropathy. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Adolescent↗

PubMed2006

Extracellular matrix dynamics associated with tissue-engineered intravascular sclerotherapy.

BACKGROUND: The extracellular dynamics after intravascular sclerotherapy with an injectable, fibroblast-based engineered construct is unknown. METHODS: Rabbits underwent ethanol sclerotherapy of a jugular vein segment. Control animals (n = 40) underwent no further treatment or an acellular collagen hydrogel was injected. Experimental animals (n = 20) received a tissue-engineered construct. After 1, 2, 4, and 20 to 24 weeks, segments were evaluated for collagen, glycosaminoglycan (GAG), matrix metalloproteinase (MMP) 2 and 9, and tissue inhibitors of MMP (TIMPs) 1 and 2 and scored on a scale of 0 to 3. Groups and time points were compared using nonparametric statistical analysis. RESULTS: Collagen content was higher in animals that received fibroblasts (P < .05). Glycosaminoglycan analysis showed a higher grade only at 1 week (P < .05). Collagen and GAG deposition were prominent at weeks 1 through 4, and decreased over time. Both MMP-2 and MMP-9 and TIMP-1 and TIMP-2 grade decreased with time (P < .01) in all groups, with no differences between groups. CONCLUSION: Enhancement of intravascular sclerotherapy by tissue engineering stems, at least in part, from increased local deposition of collagen and GAG. MMP and TIMPs may play a role in recanalization after experimental sclerotherapy. Tissue engineering may be a valuable adjunct for the treatment of vascular malformations.

Animals↗

PubMed2006

Aprotinin improves cerebral protection: evidence from a survival porcine model.

OBJECTIVE: Aprotinin is a serine protease inhibitor used during cardiac surgery to reduce blood loss and preserve platelet function. It has also been shown to reduce leukocyte activation during and after cardiopulmonary bypass. The goal of the study was to test the hypothesis that aprotinin could reduce cerebral injury after low-flow cardiopulmonary bypass and deep hypothermic circulatory arrest. METHODS: Sixteen piglets (mean weight, 13.6 +/- 1.3 kg) were randomly assigned to receive aprotinin or placebo (8 animals per group) before a 120-minute period of deep hypothermic circulatory arrest (15 degrees C) or 25 mL x kg(-1) x min(-1) low-flow cardiopulmonary bypass (25 degrees C or 34 degrees C). Piglets had a cranial window placed over the parietal cerebral cortex for direct examination of the microcirculation by means of intravital microscopy. Rhodamine-stained leukocytes were observed in postcapillary venules, with analysis for adhesion and rolling. Plasma was labeled with fluorescein isothiocyanate-dextran for assessment of functional capillary density. Neurologic and histologic scores were used as the primary outcome measures. RESULTS: During rewarming, the mean number of both rolling and adherent leukocytes was significantly lower after aprotinin administration (P < .05). At 5 and 15 minutes of rewarming, functional capillary density recovered faster with aprotinin treatment (P < .05). Functional outcome (neurologic deficit score) on postoperative day 1 was significantly improved in aprotinin-treated piglets (P < .05). CONCLUSIONS: Aprotinin reduces inflammation and improves neurologic outcome after a prolonged period of deep hypothermic circulatory arrest or low-flow cardiopulmonary bypass.

Animals↗

PubMed2006

Effects of bupivacaine and tetrodotoxin on carrageenan-induced hind paw inflammation in rats (Part 1): hyperalgesia, edema, and systemic cytokines.

BACKGROUND: Local anesthetics exert antiinflammatory actions. To elucidate potential mechanisms, the authors examined effects of bupivacaine or tetrodotoxin, administered to rats by ipsilateral or contralateral sciatic blockade or systemically, on carrageenan-induced hind paw hyperalgesia, edema, and stimulated cytokine production in circulating blood cells. METHODS: Twelve groups of rats (n = 9-12) received injections in three sites: (1) right or left hind paw (carrageenan or saline), (2) left sciatic block, and (3) systemically (subcutaneously in the upper back). Sciatic and systemic injections were performed with epinephrine plus bupivacaine, tetrodotoxin, or saline; injections were repeated 6 h later. Fifteen hours later, hyperalgesia and/or sensory and motor block were assessed behaviorally, and paw edema was quantified by magnetic resonance imaging. Stimulated production of tumor necrosis factor alpha, interleukin 10, and interleukin 1beta in whole blood cultures was measured by enzyme-linked immunosorbent assay. RESULTS: Either ipsilateral or contralateral sciatic blocks using either bupivacaine or tetrodotoxin reduced carrageenan-induced edema and hyperalgesia. Systemic bupivacaine and tetrodotoxin were ineffective in preventing edema and hyperalgesia. Bupivacaine was effective in suppressing systemic tumor necrosis factor alpha and interleukin 1beta by all three routes, whereas tetrodotoxin was ineffective by all three routes. CONCLUSION: Bupivacaine and tetrodotoxin, via a contralateral or ipsilateral sciatic block, attenuate local inflammatory edema and hyperalgesia induced by hind paw injection of carrageenan in rats. Mechanisms underlying contralateral effects of sciatic blockade remain unexplained. Bupivacaine inhibits carrageenan-evoked systemic cytokine production by a mechanism not shared by tetrodotoxin; this action may involve tetrodotoxin-resistant sodium channels or a variety of non-sodium-channel targets.

Animals↗

PubMed2006

Patellofemoral pain syndrome: evaluation of location and intensity of pain.

OBJECTIVES: To identify the sites and intensity of pain in patients with patellofemoral pain syndrome. METHOD: A prospective cohort study was conducted at an academic sports medicine practice in Boston, Massachusetts. All patients met inclusion criteria and were enrolled and evaluated during the study time frame. A single sports medicine orthopaedic surgeon examined a consecutive sample of patients with patellofemoral pain not explained by one of several well-defined anterior knee pain diagnoses. The study group consisted of 100 patients (75 females, 25 males) with median age of 14 years. Eleven discrete locations were palpated for tenderness. Hamstring tightness was evaluated by measuring the popliteal angle. Patients reported intensity of pain using a 0- to 9-point ordinal scale. Regression and nonparametric statistical methods were used. RESULTS: The most common site of pain was the patella during anterior-posterior compression (90 patients), followed by the distal pole of the patella, the medial plica, and the nonarticular medial femoral condyle. Median "worst pain" intensity was 6 out of a possible 9. The most common site of "worst pain" was also the patella in compression (63 patients). Median duration of symptoms was 10 months, with an interquartile range of 3 to 20 months. Pain intensity was inversely correlated with duration of symptoms (P < 0.01). CONCLUSIONS: In these patients with patellofemoral pain syndrome, the major source of pain was the patella subchondral bone.

Adolescent↗

PubMed2006

Complex regional pain syndromes in children and adolescents: regional and systemic signs and symptoms and hemodynamic response to tilt table testing.

OBJECTIVE: Complex regional pain syndromes (CRPS) involve neuropathic limb pain and localized circulatory abnormalities. The authors hypothesized that (1) pediatric CRPS patients exhibit systemic autonomic symptoms and orthostatic and/or cardiac sympatho-vagal dysregulation and (2) their orthostatic regulation differs from healthy controls and pediatric patients with postural orthostatic tachycardia syndrome (POTS). METHODS: CRPS children and adolescents (n=20) underwent a 6-week trial of physical therapy and cognitive-behavioral treatment. Measures included pain and function scores, regional and systemic autonomic symptom profiles, heart rate and blood pressure with tilt, heart rate variability indices, and baroreflex gain. Systemic autonomic symptoms were recorded in 55 healthy pediatric controls. Tilt responses in CRPS patients were compared with those of 21 POTS patients and 39 healthy controls. RESULTS: CRPS patients' regional autonomic symptoms, pain, and limb function improved over 6 weeks (P<0.01). At baseline CRPS patients reported more systemic autonomic symptoms than controls (P<0.05). Tilt table test showed orthostatic stability, but the mean heart rate increase with tilt was greater in CRPS patients than controls (P<0.001). POTS patients showed significant increases with tilt in mean heart rate and diastolic and systolic blood pressures compared with controls (P<0.001). There were significant increases in the mean systolic and diastolic blood pressures in POTS compared with CRPS patients but no difference in the mean heart rate between groups. DISCUSSION: CRPS patients reported multiple regional and systemic autonomic symptoms that improved during the study course, and they experienced minimal and transient tilt table-induced hemodynamic changes compared with POTS patients but relatively similar to controls.

Adolescent↗

PubMed2006

Total phenytoin concentrations do not accurately predict free phenytoin concentrations in critically ill children.

OBJECTIVE: To determine the relationship between estimated free, measured free, and measured total phenytoin levels in critically ill pediatric patients, assess the utility of the Sheiner-Tozer equation in predicting free phenytoin levels, and identify comedications that may influence phenytoin binding or confound attempts to maintain therapeutic concentrations. DESIGN: Retrospective chart review. SETTING: Twenty-four-bed medical-surgical pediatric intensive care unit. PATIENTS: Sixty critically ill pediatric patients receiving phenytoin for treatment of seizures in a large multidisciplinary intensive care unit. INTERVENTIONS AND MAIN RESULTS: The linear correlation between free and total phenytoin concentrations was moderate (r = .795), but the mean difference between actual free concentrations and those estimated from total concentrations using the Sheiner-Tozer equation was -0.31 +/- 0.5 microg/mL (95% confidence interval, -1.3 to 0.7). This difference was of concern, as 10% of patients had toxic free levels (>2 microg/mL) when simultaneously measured total levels were therapeutic (<20 microg/mL). The mean free/total phenytoin ratio was 0.13 +/- 0.07 (range, 0.06-0.42) and varied considerably among patients. Free fractions were particularly elevated in children whose serum albumin concentrations were <2.5 g/dL (0.22, p < .001). However, the relationship between free phenytoin and serum albumin concentration appeared to be nonlinear. Coadministration of valproic acid and cefazolin also increased free fraction (p < .001). CONCLUSIONS: Measured total phenytoin concentrations are unreliable for directing therapy in critically ill children. In part, this is because phenytoin binding shows greater variability in this population than has been reported in adults. This phenomenon is exacerbated by coadministration of other highly protein-bound drugs. Instead, free phenytoin concentrations should be routinely measured in critically ill children to prevent possible intoxications and ensure therapeutic dosing. Corrections using the Sheiner-Tozer equation were unreliable.

Adolescent↗

PubMed2006

Fetal hepatic haematopoiesis is modulated by arterial blood flow to the liver.

We describe an as yet unrecognised relationship between fetal hepatic haematopoiesis and arterial blood flow to the liver. To increase hepatic arterial flow, the common bile duct (CBD) was ligated in fetal lambs. Reduction of hepatic arterial flow was accomplished in age-matched animals by hepatic artery (HA) ligation. Multiple analyses performed before term showed a significant increase in haematopoietic cell density in CBD animals when compared with sham controls and HA animals. In contrast, HA animals demonstrated a decrease in liver haematopoietic activity. Fetal hepatic haematopoiesis is dependent upon arterial blood flow to the liver.

Animals↗

PubMed2006

Value of bispectral index monitor in differentiating between moderate and deep Ramsay Sedation Scores in children.

BACKGROUND: Pediatric patients who undergo diagnostic radiological imaging studies routinely require moderate or deep sedation to a Ramsay Sedation Score (RSS) of 4 or 5, respectively. The correlation between moderate and deep RSS and bispectral index (BIS) in children has never been validated. This study was designed to determine whether the BIS values correlate with RSS of children sedated for diagnostic imaging studies. METHODS: After Institutional Review Board approval, data were prospectively collected on all children receiving pentobarbital alone for computed tomography or magnetic resonance imaging. On arrival in the recovery room, any child assigned a Ramsay score of 4 or 5 was subsequently monitored with the BIS. Receiver-operating characteristic (ROC) analysis was used to evaluate the discriminative ability of BIS in differentiating depth of anesthesia. RESULTS: A total of 86 children over 1 year of age were enrolled. Children with Ramsay 4 (moderate) and Ramsay 5 (deep) sedation scores showed no significant difference in age or pentobarbital dose (mg.kg(-1)). BIS values followed a normal Gaussian-shaped distribution for both Ramsay scores. There was no significant difference in mean BIS values between the Ramsay groups (P = 0.64). There was a wide variation in BIS values (range of 31-90), which demonstrates that the BIS monitor does not correlate with the clinically assigned RSS depth of anesthesia in children. The ROC curve for BIS is equivalent to a line of nondiscrimination. CONCLUSION: BIS has limited ability to distinguish between moderate and deep Ramsay sedation levels in children who receive pentobarbital sedation for diagnostic imaging studies.

Child↗

PubMed2006

Radiation exposure reduction during voiding cystourethrography in a pediatric porcine model of vesicoureteral reflux.

PURPOSE: To compare grid-controlled variable-rate pulsed fluoroscopy (GCPFL) and continuous fluoroscopy (CFL) for the reduction of radiation exposure during voiding cystourethrography (VCUG) in a pediatric porcine model of vesicoureteral reflux. MATERIALS AND METHODS: Institutional animal care and use committee approval was obtained. Vesicoureteral reflux was simulated in four pigs, and 48 VCUG studies were performed (24 with GCPFL, 24 with CFL). VCUG was performed at abdominal girths of 8-10 cm (group 1, simulates human newborn to 6-month-old infant), 12-13 cm (group 2, simulates 2-3-year-old child), and 15-17 cm (group 3, simulates 10-year-old child). An electronic device calculated total radiation exposure during fluoroscopy and image recording. With five-point ordinal scales, VCUG images were scored independently for anatomic conspicuity and overall diagnostic quality by two radiologists (radiologists A and B). An analysis of variance was used to compare radiation exposures and fluoroscopy times between GCPFL and CFL and to determine whether radiation exposure and fluoroscopy time were dependent on the pig's abdominal girth. The Pearson product-moment correlation coefficient was used to assess whether fluoroscopy time was correlated with radiation exposure. Anatomic conspicuity and diagnostic quality scores were compared by means of the Wilcoxon signed rank test. RESULTS: Results of analysis of variance revealed that GCPFL resulted in a significant reduction in total radiation exposure compared with CFL for each of the three groups (P < .05 for each comparison), and this reduction was most marked in the larger animals. There were no significant differences in diagnostic quality of the recorded VCUG images (P > .05). Anatomic conspicuity was not significantly different for groups 2 and 3, but there was a significantly higher score for GCPFL in group 1 for radiologist A (P = .04). CONCLUSION: By using GCPFL in the performance of VCUG in a pediatric porcine model of vesicoureteral reflux, total radiation exposure can be reduced by a factor of 4.6-7.5 lower than with CFL, and diagnostic-quality images can be obtained.

Analysis of Variance↗

PubMed2006

Gadolinium-enhanced MR images of the growing piglet skeleton: ionic versus nonionic contrast agent.

PURPOSE: To determine whether there are differences in the distribution of ionic and nonionic gadolinium-based contrast agents by evaluating contrast enhancement of the physis, epiphyseal cartilage, secondary ossification center, and metaphysis in the knees of normal piglets. MATERIALS AND METHODS: Following approval from the Subcommittee on Research Animal Care, knees of 12 3-week-old piglets were imaged at 3-T magnetic resonance (MR) imaging after intravenous injection of gadoteridol (nonionic contrast agent; n = 6) or gadopentetate dimeglumine (ionic contrast agent; n = 6). Early enhancement evaluation with gradient-echo MR imaging was quantified and compared (Student t test) by means of enhancement ratios. Distribution of contrast material was assessed and compared (Student t test) by means of T1 measurements obtained before and at three 15-minute intervals after contrast agent administration. The relative visibility of the physis, epiphyseal cartilage, secondary ossification center, and metaphysis was qualitatively assessed by two observers and compared (Wilcoxon signed rank test). Differences in matrix content and cellularity that might explain the imaging findings were studied at histologic evaluation. RESULTS: Enhancement ratios were significantly higher for gadoteridol than for gadopentetate dimeglumine in the physis, epiphyseal cartilage, and secondary ossification center (P < .05). After contrast agent administration, T1 values decreased sharply for both agents-but more so for gadoteridol. Additionally, there was less variability in T1 values across structures with this contrast agent. Gadoteridol resulted in greater visibility of the physis, while gadopentetate dimeglumine resulted in greater contrast between the physis and metaphysis (P < .05). CONCLUSION: The results suggest different roles for the two gadolinium-based contrast agents: The nonionic contrast medium is better suited for evaluating perfusion and anatomic definition in the immature skeleton, while the ionic contrast medium is better for evaluating cartilage fixed-charge density.

Animals↗