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Biomedical subjects

R W Day

Publications and source records attributed to R W Day.

At least 19 recordsLinked to original sources
PubMed2005

Childhood leukaemia in Belarus, Russia, and Ukraine following the Chernobyl power station accident: results from an international collaborative population-based case-control study.

BACKGROUND: There is little evidence regarding the risk of leukaemia in children following exposure to radionuclides from the Chernobyl Nuclear Power Plant explosion on April 26, 1986. METHODS: This population-based case-control study investigated whether acute leukaemia is increased among children who were in utero or <6 years of age at the time of the Chernobyl accident. Confirmed cases of leukaemia diagnosed from April 26, 1986 through December 31, 2000 in contaminated regions of Belarus, Russia, and Ukraine were included. Two controls were matched to each case on sex, birth year, and residence. Accumulated absorbed radiation dose to the bone marrow was estimated for each subject. RESULTS: Median estimated radiation doses of participants were <10 mGy. A significant increase in leukaemia risk with increasing radiation dose to the bone marrow was found. This association was most evident in Ukraine, apparent (but not statistically significant) in Belarus, and not found in Russia. CONCLUSION: Taken at face value, these findings suggest that prolonged exposure to very low radiation doses may increase leukaemia risk as much as or even more than acute exposure. However the large and statistically significant dose-response might be accounted for, at least in part, by an overestimate of risk in Ukraine. Therefore, we conclude this study provides no convincing evidence of an increased risk of childhood leukaemia as a result of exposure to Chernobyl radiation, since it is unclear whether the results are due to a true radiation-related excess, a sampling-derived bias in Ukraine, or some combination thereof. However, the lack of significant dose-responses in Belarus and Russia also cannot convincingly rule out the possibility of an increase in leukaemia risk at low dose levels.

Age Distribution↗
PubMed2001

Cerebral blood flow velocity acutely decreases in newborns who respond to inhaled nitric oxide.

Regional cerebral blood flow is directly proportional to the Doppler velocity time integral of flow in corresponding cerebral arteries. This study was performed to determine whether an acute change in the velocity time integral of cerebral blood flow occurs in newborns with pulmonary hypertension who experience an acute improvement in pulmonary hemodynamics and gas exchange at the onset of inhaled nitric oxide therapy. Twenty-two newborns with lung disease and an oxygenation index >25 were treated with 10 to 20 parts per million inhaled nitric oxide. Measurements of heart rate, blood pressure, arterial blood gases, right and left ventricular planimetry, and Doppler ultrasonography were performed before and after 30 to 60 minutes of therapy. Nitric oxide inhalation was associated with a significant acute change in arterial blood pressure, pH, arterial carbon dioxide tension, arterial oxygen tension, proportion of right-to-left ductal shunt, estimated systolic pulmonary arterial pressure, and right ventricular diastolic and systolic areas. In the middle cerebral artery, peak systolic flow velocity (49+/-5 vs. 41+/-4, cm/sec), diastolic flow velocity (21+/-3 vs. 14+/-3, cm/sec), and the velocity time integral (10.3+/-1.1 vs. 7.9+/-1.1, cm) all decreased (p<0.05). These changes only occurred in a subgroup of 17 patients who experienced an improvement in arterial oxygen tension > or =10 mm Hg. The velocity time integral of flow in the middle cerebral artery is acutely decreased in newborns with pulmonary hypertension who experience an acute increase in oxygenation after the onset of inhaled nitric oxide.

Administration, Inhalation↗
PubMed2000

Randomized controlled study of inhaled nitric oxide after operation for congenital heart disease.

BACKGROUND: Inhaled nitric oxide selectively decreases pulmonary vascular resistance. This study was performed to determine whether inhaled nitric oxide decreases the incidence of pulmonary hypertensive crises after corrective procedures for congenital heart disease. METHODS: Patients with a systolic pulmonary arterial pressure of 50% or more of the systolic systemic arterial pressure during the early postoperative period were randomized to receive 20 parts per million inhaled nitric oxide (n = 20) or conventional therapy alone (n = 20). Acute hemodynamic and blood gas measurements were performed at the onset of therapy. The efficacy of sustained therapy was determined by comparing the number of patients in each group who experienced a pulmonary hypertensive crisis. RESULTS: In comparison to controls, there were no significant differences in the baseline and 1-hour measurements of patients who were treated with nitric oxide. Four patients in the control group and 3 patients in the nitric oxide group experienced a pulmonary hypertensive crisis. CONCLUSIONS: Nitric oxide did not substantially improve pulmonary hemodynamics and gas exchange immediately after operation for congenital heart disease. Nitric oxide also failed to significantly decrease the incidence of pulmonary hypertensive crises.

Administration, Inhalation↗
PubMed2000

Growth of children with a functionally single ventricle following palliation at moderately increased altitude.

The bidirectional Glenn and Fontan procedures are empirically performed as interim and definitive procedures in children with a functionally single ventricle. The optimal stage of palliation, nonetheless, remains unknown. During childhood, growth is a fundamental measure of response to therapy. Growth may be influenced by the degree of cyanosis, the volume load on the ventricle, and cardiac performance. Thus, the weight and stature of children with a functionally single ventricle who underwent a bidirectional Glenn procedure or a Fontan procedure were studied to determine the effect of each intervention on growth. Z scores for weight and stature were retrospectively determined prior to palliation, at yearly intervals for 4 years, and from long-term measurements until 18 years of age in all patients with at least 2 years of observation following palliation. Growth was evaluated in 54 patients with a bidirectional Glenn procedure, and 65 patients with a Fontan procedure. The Z scores for weight were improved after each method of surgical palliation. Stature, however, was improved only following the bidirectional Glenn procedure. Growth was impaired in patients who developed protein losing enteropathy. Weight improved only during the initial 2 years after the Fontan procedure in patients who had a surgical fenestration. Over the long-term, patients who underwent a Fontan procedure were more likely to have a Z score less than -2.0 for weight and stature than patients who underwent only a bidirectional Glenn procedure. Late mortality and the incidence of heart transplantation were increased in patients who experienced a decrease in their rate of growth, defined as a negative change of more than one Z score in weight or stature, following the Fontan procedure. In conclusion, at moderately increased altitude, children with a functionally single ventricle grow more appropriately following the bidirectional Glenn procedure than following the Fontan procedure. A decrease in the rate of growth is associated with a poor prognosis following the Fontan procedure.

Altitude↗
PubMed2000

Can Doppler systemic venous flow indices predict central venous pressure in children?

Tricuspid valve, superior vena cava (SVC), and hepatic vein Doppler patterns may be abnormal in right heart anomalies and have been used to predict high central venous pressure (CVP) in adults. The purpose of this study was to evaluate the relationship of these systemic venous flow indices to CVP in children. Children undergoing cardiac catheterization were studied prospectively using simultaneous recordings of mean CVP with pulsed-Doppler tracings of SVC, hepatic vein, and tricuspid valve flow. Systemic venous Doppler measurements included peak velocities and velocity time integrals for ventricular systole (S), ventricular diastole (D), and ventricular systole (B), and atrial systole (A). Tricuspid inflow Doppler E and A waves were recorded also. Patients with significant tricuspid stenosis or regurgitation, systemic venous obstruction, and nonsinus rhythm were excluded. The 42 patients ranged in age from 0.2 to 21.0 years and in weight from 3.0 to 68.0 kg. Mean CVPs ranged from 1 to 17 mmHg. Catheterization indications included hemodynamic evaluation (25 patients), transplant biopsy, (11 patients), and interventional procedures (6 patients). No SVC or tricuspid valve Doppler measurement correlated with CVP. Hepatic vein peak D, peak B, and peak A significantly correlated with CVP (r = 0.34 - 0.55; P < 0.05, linear regression). For all correlations, the r values were low with significant overlap among patients. Thus, in children, only hepatic vein peak velocities correlate with CVP. Because of the low r values and significant overlap among patients, the currently used Doppler indices have a low sensitivity for predicting CVP in this age group.

Adolescent↗
PubMed1999

Septal cystic mass in the right atrium: echocardiographic evaluation.

Right atrial masses rarely are seen in children and are usually benign. Clinical manifestations mainly depend on the location of the mass and whether it alters blood flow. This report describes the clinical course, echocardiographic findings, pathology, and serial follow-up of an unusual cystic mass with a mixture of tissue common to the atrioventricular septum located in the posteroinferior right atrium.

Cysts↗
PubMed1998

Pulmonary vascular resistance of children treated with nitrogen during early infancy.

BACKGROUND: We have empirically used supplemental nitrogen in newborns with a functional single ventricle and ductal-dependent systemic perfusion to prevent pulmonary vasodilation and deliver a greater proportion of flow to the systemic circulation. Thus, we reviewed patient outcome to determine whether adverse pulmonary vascular effects may be associated with this therapy. METHODS: From December 1991 to December 1995, the fraction of inspired oxygen was adjusted, with supplemental nitrogen if necessary, to maintain an oxygen saturation near 75% in 20 newborns awaiting heart transplantation. Medical records were reviewed to evaluate (1) the duration of nitrogen therapy, (2) pulmonary vascular histology, (3) postoperative pulmonary hemodynamics, and (4) survival. RESULTS: Thirteen patients underwent heart transplantation, 4 patients died without surgical intervention, and 3 patients underwent late aortic reconstruction. Supplemental nitrogen was used without exceeding a fraction of inspired oxygen of 0.21 for 38 +/- 6 days. One patient had evidence of changes of potentially irreversible pulmonary vascular disease. Pulmonary vascular resistance was not increased long-term in surviving patients. CONCLUSIONS: Supplemental nitrogen can be used to maintain a systemic oxygen saturation near 75% for an extended period in newborns with ductal-dependent systemic perfusion with no long-term adverse effect on pulmonary vascular resistance.

Administration, Inhalation↗
PubMed1998

Late results and reintervention after aortic valvotomy for critical aortic stenosis in neonates and infants.

BACKGROUND: Many centers have adopted balloon valvuloplasty for treatment of infants with critical aortic stenosis because of historically poor early results and a lack of long-term results with surgical valvotomy. We evaluated our results with open aortic valvotomy over the past decade, specifically examining factors influencing survival and reintervention in the current era. METHODS: From 1986 to 1996, 37 infants in the first 3 months of life underwent open aortic valvotomy for critical aortic stenosis. All patients underwent cardiopulmonary bypass, valvotomy, and valve debridement under direct vision with standard techniques. RESULTS: Early mortality was 11% (4 of 37, 70% confidence limit 7% to 20%) and all early deaths were in neonates less than 2 weeks of age. Late death occurred in 6 patients a mean of 10 +/- 12 months (range, 2 to 36 months) after valvotomy. Actuarial survival, including operative deaths was 92% +/- 6% at 1 month, 78% +/- 9% at 1 year, and 73.4% +/- 10% at 10 years. In a multifactorial regression analysis, the best predictors of death were the presence of endocardial fibroelastosis and small body surface area and the best predictor of the need for late reintervention was preoperative aortic annular size. Thirteen patients required reintervention: repeat operation in 7 patients, balloon valvuloplasty in 3 patients, and both balloon valvuloplasty and reoperation in 3 patients. Actuarial freedom from reintervention postoperatively is 97% +/- 3% at 1 month, 73% +/- 9% at 1 year, and 55% +/- 11% at 10 years. Reintervention was for recurrent left ventricular outflow obstruction in 9 patients and mixed aortic stenosis and aortic insufficiency in 4. Echocardiography 4.3 +/- 2.5 years after aortic valvotomy in survivors who have not required reintervention (n = 20) revealed a Doppler peak instantaneous systolic gradient of 37 +/- 14 mm Hg and mild or less aortic regurgitation in 16 patients and moderate aortic regurgitation in 4 patients. CONCLUSIONS: Current surgical results with critical aortic stenosis in the neonate and young infant are acceptable in terms of both late survival, reintervention, and functional results in the majority of patients. Newer interventions, such as balloon valvuloplasty, should be carefully evaluated for long-term results and should be compared more appropriately to current surgical results to determine the best treatment modality for the neonate and infant with critical aortic stenosis.

Actuarial Analysis↗
PubMed1998

Right ventricular size is acutely decreased by inhaled nitric oxide in newborns with pulmonary hypertension.

The pressure and volume demands of the right and left ventricles may dramatically change following selective pulmonary vasodilation in newborns with pulmonary hypertension. Thus, ventricular planimetry was performed by two-dimensional echocardiography in 35 newborns with lung disease and increased pulmonary vascular resistance who were treated with inhaled nitric oxide to determine the influence of therapy on right and left ventricular size and function. The end-diastolic and end-systolic areas of each ventricle were measured from apical 4-chamber images before, and 30 to 60 minutes after, the onset of 20 parts per million inhaled nitric oxide. Estimates of ventricular function were determined by the systolic decrease in ventricular area, (diastolic area - systolic area) x 100/diastolic area. Heart rate, systemic blood pressure, and left ventricular areas did not change. However, the oxygenation index, the proportion of right-to-left ductal shunt (nonrestrictive ductus arteriosus, n = 22), the systolic pulmonary arterial pressure (closed or restrictive ductus arteriosus, n = 13), and the right ventricular diastolic and systolic areas were decreased after nitric oxide inhalation. The baseline systolic decrease in left ventricular area was lower in a subgroup of patients who developed an increase in left ventricular diastolic area following nitric oxide inhalation. Thus, nitric oxide improves pulmonary hemodynamics and decreases right ventricular size in newborns with lung disease and pulmonary hypertension. However, newborns may develop an increase in left ventricular size if left ventricular function is decreased prior to therapy.

Administration, Inhalation↗
PubMed1998

Inhaled nitric oxide versus conventional therapy: effect on oxygenation in ARDS.

A randomized, controlled clinical trial was performed with patients with acute respiratory distress syndrome (ARDS) to compare the effect of conventional therapy or inhaled nitric oxide (iNO) on oxygenation. Patients were randomized to either conventional therapy or conventional therapy plus iNO for 72 h. We tested the following hypotheses: (1) that iNO would improve oxygenation during the 72 h after randomization, as compared with conventional therapy; and (2) that iNO would increase the likelihood that patients would improve to the extent that the FI(O2) could be decreased by > or = 0.15 within 72 h after randomization. There were two major findings. First, That iNO as compared with conventional therapy increased Pa(O2)/FI(O2) at 1 h, 12 h, and possibly 24 h. Beyond 24 h, the two groups had an equivalent improvement in Pa(O2)/FI(O2). Second, that patients treated with iNO therapy were no more likely to improve so that they could be managed with a persistent decrease in FI(O2) > or = 0.15 during the 72 h following randomization (11 of 20 patients with iNO versus 9 of 20 patients with conventional therapy, p = 0.55). In patients with severe ARDS, our results indicate that iNO does not lead to a sustained improvement in oxygenation as compared with conventional therapy.

Administration, Inhalation↗
PubMed1997

Common cardiovascular problems in the young: Part II. Hypertension, hypercholesterolemia and preparticipation screening of athletes.

Blood pressure should be measured during health maintenance visits in all children three years of age and older. Cholesterol levels should be obtained in children with a family history of hypercholesterolemia or premature coronary artery disease and in children with other risk factors, such as hypertension, smoking or obesity. Preparticipation screening for sports participation should include a detailed questionnaire regarding the athlete's personal or family history of syncope, sudden death or arrhythmia, as well as measurement of blood pressure, auscultation of the heart and evaluation of upper and lower extremity pulses.

Adolescent↗
PubMed1997

A randomized, controlled study of the 1-hour and 24-hour effects of inhaled nitric oxide therapy in children with acute hypoxemic respiratory failure.

STUDY OBJECTIVE: To determine whether 24 h of inhaled nitric oxide improves oxygenation greater than conventional therapy alone in children with acute hypoxemic respiratory failure. DESIGN: Prospective, randomized, controlled study. SETTING: Twenty-six-bed pediatric ICU in a tertiary children's hospital. PATIENTS: Twenty-four patients with acute bilateral lung disease requiring a positive-end expiratory pressure >6 cm H2O and a fraction of inspired oxygen >0.5 for >12 h. INTERVENTIONS: Twelve patients were treated with 10 ppm inhaled nitric oxide from the onset of randomization and 12 control patients were initially maintained on a regimen of conventional therapy alone. After a period of 24 h, control patients were also treated with 10 ppm inhaled nitric oxide. Hemodynamic and blood gas measurements were performed at baseline, at 1 h after randomization, and at 24-h intervals for 2 days. MEASUREMENTS AND RESULTS: Inhaled nitric oxide decreased the ratio of pulmonary to systemic vascular resistance and improved oxygenation indexes during the initial hour following randomization. However, 24 h after randomization, the oxygenation indexes of 11 surviving treated patients were not improved in comparison to baseline or the oxygenation indexes of 10 surviving control patients. Oxygenation indexes acutely improved in control patients when inhaled nitric oxide was started after 24 h of conventional therapy. Oxygenation indexes remained improved in the initial control patients after 24 h of inhaled nitric oxide. CONCLUSIONS: Pulmonary vascular resistance and systemic oxygenation are acutely improved by 10 ppm inhaled nitric oxide in some children with severe lung disease. However, a sustained improvement in oxygenation may not occur during prolonged therapy. Thus, inhaled nitric oxide may have a limited therapeutic role in children with acute hypoxemic respiratory failure.

Acute Disease↗