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Biomedical subjects

R W Day

Publications and source records attributed to R W Day.

At least 37 records · Page 2Linked to original sources
PubMed1997

Doppler evaluation of aortic regurgitation in children.

Doppler indexes have been used successfully to determine the severity of aortic regurgitation (AR) in adults but have not been evaluated systematically in children. To evaluate the accuracy of specific Doppler echocardiographic indexes in assessing the degree of AR in children, 30 children underwent 2-dimensional and Doppler echocardiography within 24 hours of angiography. Patients were divided into 4 groups based on the degree of angiographic AR. Color Doppler jet width, short-axis jet area, jet length, and maximum jet area were measured. AR slope was measured using continuous-wave Doppler. Flow in the abdominal aorta was evaluated using pulsed Doppler. Doppler indexes were compared with the angiographic grade of AR. Jet width and short-axis jet area were significantly different between groups and showed strong correlation with the angiographic grade. Holodiastolic flow reversal in the abdominal aorta separated 1+ to 2+ from 3+ to 4+ AR (100% sensitivity and 100% negative predictive value for 3+ to 4+ AR). Jet length, maximum jet area, and the ratio of reverse to forward abdominal aortic velocity time integrals correlated with angiography but showed little difference between groups that differed by only 1 angiographic grade. AR slope did not correlate with the angiographic grade. We conclude that in children, color Doppler jet width, short-axis jet area, and holodiastolic abdominal aortic flow reversal are the best predictors of angiographic severity. Use of these indexes may obviate the need for angiography to determine the degree of AR in children.

Aortic Valve↗
PubMed1997

Pulmonary intravascular ultrasound in infants and children with congenital heart disease.

A three-layered appearance of the pulmonary arterial wall has only been described by intravascular ultrasound in adults or autopsy studies of patients with pulmonary hypertension. Thus, pulmonary intravascular ultrasound was performed in 11 patients during heart catheterization to test the hypothesis that distinct layers of peripheral pulmonary arteries can be imaged in infants and children with congenital heart disease. A 3.5 Fr 30 MHz ultrasound catheter was used to image proximal pulmonary arteries with an internal diameter of 3 to 6 mm and distal pulmonary arteries with an internal diameter of 1.5 to 2 mm. Three layers were identified in the proximal arteries of 10 patients but could not be identified in the distal arteries of any patient. There was a significant linear correlation between the indexed dimension of the medial echolucent vascular wall layer and pulmonary vascular resistance. We conclude that intravascular ultrasound can identify vascular changes consistent with medial hypertrophy in the branch pulmonary arteries of young patients with corresponding degrees of pulmonary hypertension.

Cardiac Catheterization↗
PubMed1996

Inhaled nitric oxide in children with severe lung disease: results of acute and prolonged therapy with two concentrations.

OBJECTIVES: To evaluate the acute effects of 11 and 60 parts per million (ppm) inhaled nitric oxide on the pulmonary vascular resistance and systemic oxygenation of children with severe lung disease, and to compare the outcome of prolonged therapy with approximately 10 and 40 ppm inhaled nitric oxide. DESIGN: Prospective, randomized study. SETTING: A 26-bed pediatric intensive care unit in a tertiary children's hospital. PATIENTS: Nineteen patients (median age 11 yrs, range 7 months to 16 yrs) with acute bilateral lung disease requiring a positive end-expiratory pressure (PEEP) of > 6 cm H2O and an FIO2 of > 0.5 for > 12 hrs were treated with inhaled nitric oxide. One patient was treated twice during the same hospitalization. INTERVENTIONS: Acute hemodynamic and blood gas effects of 11 and 60 ppm inhaled nitric oxide were studied, while delivering these concentrations in random order for intervals of 20 to 30 mins. Each interval was preceded by an interval of 20 to 30 mins without nitric oxide. Patients were then randomized and treated for a prolonged period with approximately 10 or 40 ppm inhaled nitric oxide independent of their initial acute responses to 11 and 60 ppm. Nitric oxide was discontinued when ventilatory support was decreased to a PEEP of < or = 6 cm H2O and an FIO2 of < or = 0.5. MEASUREMENTS AND MAIN RESULTS: Inhaled nitric oxide selectively decreased pulmonary vascular resistance and improved systemic oxygenation. Acute hemodynamic and blood gas effects of 11 and 60 ppm nitric oxide were similar. Systemic oxygenation improved to a greater extent in patients with radiographic evidence of residual aerated lung regions than in patients with diffuse bilateral lung disease. Maximum methemoglobin concentrations were greater in patients treated for a prolonged period with 40 ppm nitric oxide. The mortality and duration of therapy were similar for patients treated with 10 and 40 ppm inhaled nitric oxide. CONCLUSIONS: Pulmonary vascular resistance and systemic oxygenation are acutely improved to a similar extent by 11 and 60 ppm inhaled nitric oxide, and concentrations in excess of 10 ppm are probably not needed for prolonged therapy of children with severe lung disease.

Administration, Inhalation↗
PubMed1996

The effect of inhaled nitric oxide in pediatric asthma.

Nitric oxide (NO) appears to play an important role in regulating several biologic functions in the lung, including modulation of pulmonary arterial and bronchial smooth muscle tone. Recent studies have shown that relatively high concentrations of inhaled NO reduce the bronchoconstrictor effect of methacholine in animal models. This raises the possibility that NO inhalation might have therapeutic potential as an alternative bronchodilator. Although investigation of this potential in adults with airway reactivity or bronchial asthma has been reported, data are lacking on the role of NO in the pediatric asthma population. We therefore performed spirometry on 12 children with asthma (mean age 11.1 yrs) at baseline (B), immediately after inhaling 40 ppm NO (NO-1), 10 min after inhaling NO (NO-10), and after inhalation of a standard beta 2-agonist, albuterol (A). Baseline pulmonary functions (% predicted +/- SEM) were FVC of 103.2 +/- 5.6, FEV1 of 82.2 +/- 3.3, FEF-max of 97.0 +/- 3.6, and FEF25-75% of 53.5 +/- 3.3. There were no statistically significant differences between baseline and NO-1 or NO-10 between any of the four pulmonary function parameters measured. Inhaled albuterol, however, resulted in significant improvement (% predicted +/- SEM) in FVC to 109.8 +/- 3.5, FEV1 to 99.7 +/- 2.9, FEFmax to 106.5 +/- 5.1, and FEF25-75% to 84.4 +/- 6.4 compared with the baseline and NO inhalation groups. We conclude that NO inhaled at 40 ppm has no apparent bronchodilatory effect in pediatric subjects with asthma and mild airways disease. The clinical application of this gas as a therapeutic modality under these conditions is questionable.

Administration, Inhalation↗
PubMed1996

Acute response to inhaled nitric oxide in newborns with respiratory failure and pulmonary hypertension.

OBJECTIVE: Systemic oxygenation is improved by inhaled nitric oxide therapy in some newborns with respiratory failure and pulmonary hypertension. Our results with inhaled nitric oxide were reviewed to determine factors associated with an acute improvement in systemic oxygenation. METHODS: Newborns with oxygenation indices of 25 to 40 were prospectively randomized to receive conventional therapy with or without 20 ppm inhaled nitric oxide. All newborns with oxygenation indices greater than 40 were treated with inhaled nitric oxide. Hemodynamic, blood gas, and Doppler ultrasound measurements were performed before and after 30 to 60 minutes of observation or therapy. The severity of lung disease was classified by the chest radiograph as: (1) normal or focal disease; (2) moderate diffuse disease-diffuse lung disease with well-defined heart borders; or (3) severe diffuse disease-diffuse lung opacification with indistinct heart borders. RESULTS: Heart rate, blood pressure, and ductal diameters did not change. Blood gases and ductal shunting acutely improved only in patients treated with inhaled nitric oxide. Patients with normal lung fields or focal disease had the greatest degree of improvement in systemic oxygenation. Changes in oxygenation were not influenced by gestational age, baseline blood gases, the proportion of right-to-left ductal shunting, prior treatment with a surfactant, or the use of conventional or high-frequency jet ventilation. Collectively, blood gases and ductal shunting did not improve with inhaled nitric oxide in patients with lung hypoplasia or severe diffuse lung disease. Sustained improvement in oxygenation occurred in 87% of patients with oxygenation indices greater than 40 in whom oxygenation indices less than 40 acutely developed after exposure to nitric oxide, whereas 90% of patients in whom oxygenation indices less than 40 did not acutely develop were treated with extracorporeal membrane oxygenation or ultimately died. CONCLUSIONS: Inhaled nitric oxide acutely improves systemic oxygenation in many newborns with respiratory failure and pulmonary hypertension. The diagnosis and chest radiograph are helpful in identifying patients who will have favorable acute responses to therapy. In patients with severe hypoxemia, the need for invasive support with extracorporeal membrane oxygenation may be determined by an acute trial of inhaled nitric oxide.

Acute Disease↗
PubMed1994

Early and intermediate results of the Fontan procedure at moderately high altitude.

At higher elevations, alveolar hypoxia increases pulmonary vascular resistance and may limit the cardiac output of individuals without a subpulmonary ventricle. Thus, we reviewed the outcome of definitive palliation for tricuspid atresia and other forms of single ventricle in 60 consecutive Fontan patients living at a mean elevation of 1,370 m (range, 910 to 2,130 m). There were four early deaths (6.7%; 70% confidence limits, 4.1% to 10.7%) and six late deaths. Kaplan-Meier actuarial survival (+/- standard error) is 79.6% +/- 8.2% at 5 years. Survival was significantly decreased in patients with a preoperative mean pulmonary arterial pressure greater than or equal to 15 mm Hg unless the Fontan procedure was performed with a residual fenestration. Exercise tolerance was significantly worse at higher elevations in a subgroup of patients who have traveled to altitudes of 1,680 to 3,350 m. We conclude that the early and intermediate results of the Fontan procedure at moderately high altitude are similar to results reported at sea level. However, exercise tolerance may be impaired at higher elevations in many patients.

Adolescent↗
PubMed1993

Mid-term results after bidirectional cavopulmonary shunts.

Despite the increasing use of the bidirectional cavopulmonary shunt, little is known about the late results, the duration of palliation, and the frequency with which this procedure allows later successful conversion to a Fontan type of procedure. We reviewed our experience (1984 to 1992) in 38 consecutive children, ages 4 months to 16 years (mean, 4.0 years), who underwent a bidirectional cavopulmonary shunt procedure. All had a single functional ventricle and represented high risks for the performance of a Fontan procedure based on anatomic and hemodynamic criteria. The oxygen saturation in these patients improved from a preoperative value of 75% +/- 7% to 82% +/- 7% (p < 0.05) at late cardiac catheterization by a mean of 24 months after operation. The actuarial survival, including early deaths and that associated with all secondary procedures, was 86% at 1 year and 81% at 6 years. Early deaths occurred in 5.3% (2/38) and late deaths in 11% (4/36). Late follow-up ranged from 5 to 90 months (mean, 37 months). Conversion to a Fontan or fenestrated Fontan procedure was accomplished in 21 early survivors (21/36; 58%) by a mean of 26 months after the bidirectional cavopulmonary shunt procedure, with one operative and no late deaths (1/21; 4.8%). Three additional patients have undergone late reoperation, including 2 requiring cardiac transplantation and 1 undergoing the late creation of an axillary artery-to-vein fistula for the treatment of cyanosis. The midterm survival after a bidirectional cavopulmonary shunt procedure appears to be excellent, and it serves as a good staging procedure for patients who represent high risks for a Fontan procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Selective anterograde coronary arteriography in neonates with d-transposition of the great arteries: accuracy and safety.

OBJECTIVES: This study was designed to evaluate the accuracy and safety of selective anterograde coronary arteriography for the identification of the origin and branching pattern of the three main coronary arteries in neonates with d-transposition of the great arteries. BACKGROUND: Definition of coronary artery anatomy is important in neonates with d-transposition of the great arteries who are considered for the arterial switch operation. Balloon occlusion aortography defines coronary artery anatomy in most but not all cases. We have described a technique for selective anterograde coronary arteriography. METHODS: Between March 1987 and May 1991, 17 neonates underwent selective anterograde coronary arteriography and 29 patients had balloon occlusion aortography. After venous access was gained, a mesenteric catheter was used to engage the coronary ostia for contrast injection. All angiograms were reviewed by three independent observers and the coronary artery diagnoses were compared with operative findings. Complications with the catheterization procedure were also recorded. RESULTS: The accuracy of defining coronary artery anatomy with selective anterograde coronary arteriography (98 +/- 2%) was significantly (p < 0.05) greater than that achieved with balloon occlusion aortography (69 +/- 6%). There were no deaths with catheterization in either study group. Morbidity was similar in the groups with balloon occlusion aortography (7%) and selective anterograde coronary arteriography (6%) (p > 0.05) and was related to transient bradycardia induced by catheter manipulation in the right ventricle. No patient in either study group experienced cardiac ischemia. CONCLUSIONS: Selective anterograde coronary arteriography is an accurate and safe technique for the definition of coronary artery pattern in neonates with d-transposition of the great arteries.

Aortography↗
PubMed1993

Effect of depth information on a bistable spiral-motion aftereffect.

Two types of spiral-motion aftereffects were elicited by a single pattern: subjects reported seeing the pattern expand in the two-dimensional viewing plane or bulge toward them in three-dimensional space. Under binocular-viewing conditions reports of two-dimensional translations predominated. But when depth information was restricted under monocular-viewing conditions, reports of three-dimensional translations were more frequent. It appears that the bistability of these aftereffects can be influenced by the degree of depth information available about a stimulus pattern.

Attention↗
PubMed1993

Endothelium-dependent relaxation and the acute pulmonary vascular response to alveolar hyperoxia in neonatal pigs.

To determine whether hyperoxia increases the production of endothelium-derived relaxing factor, we studied the effect of oxygen on pulmonary vascular ring tension and regional lung perfusion. In vitro, hyperoxia stimulated endothelium-independent constriction of neonatal porcine pulmonary arterial rings. In vessels with intact endothelium, hyperoxia stimulated a concomitant increase in the production of endothelium-derived relaxing factor. In sedated neonatal pigs, colored microspheres were used to evaluate relative lung perfusion when two lung regions were independently ventilated with room air, and subsequently, when one lung region was ventilated with 100% oxygen. The proportion of flow to the hyperoxic lung region was not significantly increased until the production of endothelium-derived relaxing factor was inhibited by NG-monomethyl-L-arginine or NG-nitro-L-arginine methyl ester. Thus, hyperoxia stimulated opposing effects on the tension of isolated vascular rings. One mechanism of oxygen-mediated relaxation results from an increase in the production of endothelium-derived relaxing factor. However, in vivo, alveolar hyperoxia may stimulate an acute pulmonary vasodilatory response which is not mediated by endothelium-derived relaxing factor.

Analysis of Variance↗
PubMed1992

Factors influencing survival of patients with heterotaxy syndrome undergoing the Fontan procedure.

OBJECTIVES: This study was undertaken to determine those factors that may influence survival in patients with heterotaxy syndrome undergoing the Fontan procedure. BACKGROUND: The Fontan procedure remains the preferred palliative procedure for patients with heterotaxy syndrome. Although the mortality rate has improved for patients without this syndrome undergoing the Fontan procedure, it remains high for patients with heterotaxy syndrome. METHODS: The medical records of 20 consecutive pediatric patients with asplenia (n = 12) and polysplenia (n = 8) who underwent the Fontan procedure between January 1, 1986 and December 31, 1990 were reviewed. Anatomic and hemodynamic data were collected, as well as data on types of surgical palliative procedures and on outcome of the Fontan procedure. RESULTS: There were two early and two late deaths for a total mortality rate of 20% in the patients with heterotaxy syndrome, as compared with 8.5% for the patients without this syndrome who underwent the Fontan procedure during the same time period. Factors that significantly increased the risk of the Fontan procedure in these patients were 1) preoperative findings of greater than mild atrioventricular valve regurgitation, b) hypoplastic pulmonary arteries, and c) mean pulmonary artery pressure greater than or equal to 15 mm Hg after 6 months of age. Systemic and pulmonary venous anomalies coupled with single-ventricle anatomy were not significant risk factors for determining a poor outcome of the Fontan procedure. CONCLUSIONS: This study suggests that the outcome of the Fontan procedure in patients with heterotaxy syndrome may be improved by early protection of the pulmonary vascular bed, despite the existence of other cardiac anomalies.

Abnormalities, Multiple↗
PubMed1992

Oxygen-mediated regulation of neonatal and adult rabbit aortic tension.

To determine the influence of oxygen on aortic tension in young and mature animals, we evaluated the response of neonatal and adult rabbit aortic rings to changes in oxygen tension. In 95% nitrogen/5% carbon dioxide, endothelium-derived nitric oxide was not a factor in the development or maintenance of low resting aortic ring tensions. However, the production of endothelium-derived nitric oxide increased in 21% oxygen/74% nitrogen/5% carbon dioxide and 95% oxygen/5% carbon dioxide, and attenuated a concomitant endothelium-independent mechanism of increasing vascular tension. A protein kinase inhibitor, 0.2 mM 1-(5-isoquinolinyl-sulfonyl)-2-methyl piperazine (H-7) inhibited oxygen-mediated constriction of neonatal vessels, but also significantly reduced the contractile response to 60 mM KCl. In conclusion, resting aortic tension is in part determined by oxygen-mediated control of the production of endothelium-derived nitric oxide and one or more opposing endothelium-independent mechanisms of constriction.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

The influence of coronary anatomy on the arterial switch operation in neonates.

To determine whether coronary anatomy influences the outcome of the neonatal arterial switch operation, we examined the results in all newborn infants (n = 70) with D-transposition of the great arteries who had a corrective operation at our institution between March 1987 and April 1991. The origin and distribution of coronary arteries were identified preoperatively by echocardiography, aortic root angiography, or selective coronary arteriography and intraoperatively by direct inspection. However, the arterial switch operation was performed independent of the coronary anatomy in all but two candidates for the operation. Four early deaths occurred and five surviving patients had symptoms of impaired cardiac function. No late deaths have occurred in patients followed up for 2 to 50 months. Evidence of myocardial ischemia was present in three of the four deaths and in four of the five patients with cardiovascular symptoms. Patients with commissural or intramural coronary origins between the great arteries had significantly greater cardiovascular morbidity and mortality because of coronary ischemia than patients with the most common coronary pattern. Thus coronary anatomy may influence surgical management and the postoperative course of newborn infants with transposition.

Age Factors↗
PubMed1989

Description of a venous technique for selective coronary arteriography in newborns with d-transposition of the great arteries.

An accurate description of the coronary anatomy is desired before anatomic correction of d-transposition of the great arteries. Two-dimensional echocardiography and aortic root angiography are occasionally unable to delineate the coronary arteries. In neonates, the arterial approach for selective coronary arteriography is difficult and may compromise visceral and lower limb perfusion. A venous technique was used in two newborns to define selectively the coronary origins and their distribution. The venous approach for selective coronary arteriography may be effective in the evaluation of newborns with d-transposition of the great arteries when echocardiography inadequately defines the coronary circulation.

Coronary Angiography↗
PubMed1987

Medical audit in geriatric medicine.

A form developed to audit the case notes of general medical patients was modified for use in geriatric medicine. The case notes of 41 admissions to the geriatric wards of a teaching hospital were audited with the new form and their contents did not come up to the standard set. Deficiencies were found in those parts of the notes considered to reflect the distinctive features of the specialty, e.g. the functional history, the assessment of mobility and the recording of multidisciplinary case conferences. The introduction of a standard history and examination form to meet the needs of patients admitted to geriatric wards, better training in geriatric medicine for junior doctors and closer scrutiny of medical records by consultants are suggested as ways of improving documentation in the case notes.

England↗
PubMed1985

Overuse injuries.

Stress injuries common to running athletes are always associated with a breakdown of the protective mechanisms normally inherent in healthy posture and gait. It is more important to identify and treat these breakdowns of the motor process than the resulting injury itself. Simple motor screening of athletes can identify functional abnormalities that lead to stress injuries. This screen includes assessment of flexibility of all major joints, responsiveness of primary postural muscles, posture, balance, and gait. Present definitions of physical fitness are focused on cardiorespiratory function and strength and do not properly determine the ability of an athlete to run or walk. The basic motor screen outlined in this article has been shown to be of value in correcting this shortcoming.

Athletic Injuries↗