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Biomedical subjects

J B Gouyon

Publications and source records attributed to J B Gouyon.

At least 73 records · Page 4Linked to original sources
PubMed1994

Urea removal by hemofiltration and hemodiafiltration.

Continuous hemofiltration is usually regarded as a safe method for controlling fluid overload in neonates presenting acute renal failure. We considered that continuous hemodiafiltration with a hemofilter type especially designed for use in the neonatal period could improve urea removal as compared with hemofiltration. Continuous arteriovenous hemofiltration (CAVH) and hemodiafiltration (CAVHD) were consecutively performed on 7 anesthetized adult rabbits which were given an urea infusion. The hemofilter was a 800-cm2 polysulfone model (Amicon Minifilter Plus). Mean values for physiological and operational parameters were comparable during CAVH and CAVHD, i.e., mean blood pressure (69.6 +/- 14.9 and 70 +/- 13.1 mm Hg, respectively), arterial oncotic pressure (16.0 +/- 2.4 and 16.0 +/- 1.7 mm Hg), hematocrit (36.2 +/- 5.8 and 36.7 +/- 4.4%), protein plasma level (38.9 +/- 7.0 and 39.0 +/- 6.4 g/l), urea plasma level (20.6 +/- 6.5 and 19.9 +/- 7.0 mmol/l), plasma flow in the hemofilter (7.89 +/- 8.48 and 7.12 +/- 3.08 ml/min), and ultrafiltrate rate (1.17 +/- 0.49 and 1.73 +/- 0.78 ml/min). CAVHD allowed a significant increase in urea clearance (4.74 +/- 4.51 ml/min) as compared with CAVH (1.23 +/- 0.81 ml/min). These experimental results suggest that CAVHD usefulness should be assessed in neonates presenting acute renal failure.

Animals↗
PubMed1994

Removal of branched-chain amino acids by peritoneal dialysis, continuous arteriovenous hemofiltration, and continuous arteriovenous hemodialysis in rabbits: implications for maple syrup urine disease treatment.

Renal elimination of branched-chain amino acids (BCAA) is low in maple syrup urine disease, and peritoneal dialysis may be required in an emergency situation for removal of the three BCAA (leucine, isoleucine, and valine). However, failures of BCAA removal by peritoneal dialysis have been reported, especially in neonates. Therefore, we tested the ability of continuous hemofiltration and continuous hemodialysis to remove BCAA as compared with peritoneal dialysis. Experiments were conducted in 15 anesthetized adult rabbits infused with leucine, isoleucine, and valine. In group 1 (n = 7), peritoneal dialysis (dialysate = 75 mL/kg) and continuous arteriovenous hemofiltration with a polysulfone 800-cm2 hemofilter were simultaneously performed during 40 min. In group 2 (n = 8), continuous arteriovenous hemofiltration and continuous arteriovenous hemodialysis were successively performed during 30 min in a randomly settled order. Animals had high and stable BCAA plasma levels during the experimental procedure. As compared with peritoneal dialysis, continuous arteriovenous hemofiltration constantly showed a significant increase in clearances of leucine (+159 +/- 99%), isoleucine (+176 +/- 107%), and valine (+125 +/- 76%). In comparison with continuous arteriovenous hemofiltration, continuous arteriovenous hemodialysis constantly showed significant increased values in clearances of leucine (+90 +/- 43%), isoleucine (+95 +/- 45%), and valine (+99 +/- 52%). During continuous arteriovenous hemofiltration and continuous arteriovenous hemodialysis, a significant positive correlation was established between urea clearance and clearances of leucine (r2 = 0.953 and 0.927, respectively), isoleucine (r2 = 0.948 and 0.910, respectively), and valine (r2 = 0.953 and 0.864, respectively).

Amino Acids, Branched-Chain↗
PubMed1994

[Use of tissue plasminogen activator in the treatment of aortic thrombosis in newborn infants].

BACKGROUND--Aortic thrombosis is more frequent since the use of umbilical artery catheters in neonatal intensive care units. Some drugs or surgery are proposed to prevent complications; experience with tissue plasminogen activator (tPA) is still limited. CASE REPORT NO 1--A neonate, weighing 2400 g, developed respiratory distress requiring insertion of a catheter into her umbilical artery at H12. Ultrasonography on day 3 showed aortic thrombosis extending to the right renal artery which was confirmed by angiography. tPA 0.1 mg/kg was administered through the catheter, followed by 0.3 mg/kg/h for 3 hours and heparin, 100 IU/kg/hour for 54 hours. Angiography, performed 18 hours later, showed complete disappearance of the thrombosis. CASE REPORT NO 2--A neonate, weighing 2520 g suffered at 12 hours of life from seizures, apnea and bradycardia which required insertion of a catheter into her umbilical artery. Cyanosis of the right leg with weakening of femoral pulsations, 14 hours later, lead to the diagnosis of aortic thrombosis which was confirmed by aortography. The patient was given tPA 0.1 mg/kg followed by 0.3 mg/kg/h for 3 hours and heparin 100 IU/kg/hour for 6 hours. Amplitude of femoral pulsations strikingly increased within 6 hours with the disappearance of cyanosis. CONCLUSION--These results suggest that tPA can be useful in neonates presenting with aortic thrombosis.

Aorta↗
PubMed1994

[Ultrasonographic survey of the effect of umbilical arterial catheterization in newborn infants].

BACKGROUND: Incidence of aortic thromboses in the neonatal period is significantly increased after umbilicar artery catheterization. POPULATION AND METHODS: Fourty neonates (GA: 34.7 +/- 7.2 wks and birth weight: 2377 +/- 786 g) were prospectively studied in order to assess frequency and natural history of aortic thromboses due to umbilical artery catheterization. Investigation was based on serial real-time ultrasonography (2.3 times/week). Presence of aortic thrombus was correlated with the existence of clinical complications and the results of biological findings (prothrombin and fibrinogen levels; hematocrit) and platelet number. RESULTS: Aortic thrombosis was found in six patients (15%); it was clinically asymptomatic in two (5%). A vascular wall-fixed catheter was shown in ten infants (25%); this finding was associated with thrombosis in five cases and preceded thrombosis in one other. The presence of thrombus and/or abnormal position of the catheter was not correlated with gestational age, birth weight, duration of catheterization, blood hemostasis and results of bacteriological cultures of the tip of the catheter. CONCLUSIONS: Ultrasonographic control must be repeated after umbilical artery catheterization. It permits evaluation of renal flux and can lead to removal of catheter and/or peculiar therapeutic measures.

Aorta↗
PubMed1994

[Renal effects of prolonged indomethacin therapy in premature infants].

BACKGROUND: Indomethacin therapy for large patent ductus arterious would be more effective when it is prescribed for 5 or 6 days vs 2 or 3 days. Effects on renal function of such prolonged therapy is still debated. PATIENTS AND METHODS: Seven preterm infants (gestational age: 28.6 +/- 0.9 weeks; birth-weight: 1,169 +/- 267 g) with symptomatic patent ductus arterious were given indomethacin, 0.1 mg/kg/day for 6 days (four patients) and 5 days (three patients). Urinary water excretion, water output/input ratio, creatinine clearance and body weight were measured before and every day during therapy. RESULTS: Urinary water excretion, water output/input ratio and creatinine clearance were significantly decreased after 5 days of treatment, -40 +/- 30%, -42 +/- 27% and -48 +/- 31%, respectively. Creatinemia and body weight were significantly increased, + 34 +/- 36% and + 9 +/- 7%, respectively. Mean sodium plasma level and fractional excretion of sodium, potassium and chloride remained stable. CONCLUSION: Prolonged therapy with indomethacin does not avoid the renal side effects seen with shorter administration.

Dose-Response Relationship, Drug↗
PubMed1994

[Necrotizing tracheobronchitis in ventilated newborn infants].

BACKGROUND: Necrotizing tracheobronchitis is a severe complication observed in some mechanically ventilated neonates. CASE REPORT: A twin premature (GA = 31 weeks), weighing 1,500 g required oral endotracheal intubation for mechanical ventilation because he suffered from respiratory distress syndrome. He was given indomethacin on day 4 for patent ductus arteriosus. Progressive weaning of ventilation on day 9 was dramatically complicated by hypoxia, respiratory acidosis and right pneumothorax. Immediate endoscopy showed total obstruction of trachea by necrotic secretions the suction of which was followed by rapid improvement of the respiratory condition. Bacterial examination of secretions showed coagulase-negative staphylococcus. The patient was given steroids + antibiotics. Prolonged ventilation resulted in bronchopulmonary dysplasia and the patient was only extubated at week 12 after a normal endoscopic control. CASE REPORT: A premature girl (GA = 32 weeks), weighing 1,800 g required oral endotracheal intubation for mechanical ventilation because she suffered from respiratory distress syndrome. The respiratory condition worsened on day 3, requiring tracheography which showed distal tracheal obstruction. Immediate endoscopy showed thin, adherent and necrotic membranes which were removed by suction. The patient was given steroids +antibiotics and was extubated on day 14 after a normal endoscopic control. CONCLUSIONS: This iatrogeneous complication must be recognized in a ventilated infant when the respiratory condition dramatically worsens. Emergency bronchoscopy permits endotracheal suction of necrotic secretions.

Bronchitis↗
PubMed1994

[Removal of amino acids by continuous hemofiltration and hemodiafiltration].

BACKGROUND: Continuous hemodiafiltration is potentially more efficient than hemofiltration for removing low molecular metabolites. CASE REPORT: A newborn (2100 g) was admitted suffering from acute distress with statuts epilepticus, liver failure with generalized hyperaminoacidemia, hypoglycemia and oligo-anuria. Peritoneal dialysis, performed on the 17th day of life, was ineffective and the patient was treated by continuous hemofiltration alternating with hemodiafiltration. Clearance of amino-acids was studied for 15 minutes under each technique. The amino-acid concentrations were measured in the infused fluid and in the ultrafiltrate. The baby died on the 20th day despite this treatment. RESULTS: Amino acid clearance by hemodiafiltration was 181 +/- 176% greater than by hemofiltration. The mean improvement for all amino acids was 148%, with extremes of +43% for citrulline and 941% for glutamic acid. CONCLUSION: Continuous hemodiafiltration is an efficient method of removing amino acids; it could be used to treat severe inborn errors of metabolism such as leucinosis.

Acute Kidney Injury↗
PubMed1993

Assessment of urine specific gravity by reagent strip test in newborn infants.

Specific gravity was measured with a strip test (N-Labstix SG, Ames Division, Miles, Puteaux, France) in 98 urine specimens obtained from 57 newborn infants; osmolality was measured with an osmometer. The strip test did not accurately predict urine osmolalities; a very weak correlation was found between the specific gravity and the osmolality (r2 = 0.598, P < 0.01). Specific gravity values up to 1.015 always indicated hypotonic urine with osmolality less than 211 mosmol/kg H2O, whereas higher values could be associated with either hypotonic or hypertonic urine. Therefore, the strip test cannot be recommended in the neonatal period because its clinical usefulness is strictly restricted to urine samples with low specific gravities (< or = 1.015) and without confounding variables (urine pH > or = 6.5, glucosuria, proteinuria, haematuria).

Hematuria↗
PubMed1993

Dose-response study of metoclopramide in gastroesophageal reflux in infancy.

Twenty-four infants, 1 to 18 months-old, who were referred to four centers for suspected gastroesophageal reflux and whose esophageal pH after a standard formula meal given at 9 to 10 am (Ho-day 1) fulfilled the criterion of being < 4 for more than 5% of the time between H1 and H6, entered a double-blind placebo-controlled dose-response trial of metoclopramide (M). Twenty-four hours later (day 2), patients were randomly assigned to receive either placebo or a single 0.1, 0.2, or 0.4 mg/kg dose of metoclopramide, 30 min before the formula meal (n = 6/group) and the procedure was repeated. Metoclopramide plasma concentration was measured 1 h after dosing (C1h). On day 1, the time during which the esophageal pH was < 4 (time pH < 4), and five other parameters, were not significantly different in the treatment groups. On day 2, time pH < 4 (m(SD)) decreased from 33(13) to 30(33), 39(27), to 36(47), 42(15) to 18(13) and 48(25) to 31(46) min in the placebo, 0.1, 0.2, and 0.4 mg/kg metoclopramide groups, respectively. Possibly due to the large interindividual variability, no significant differences in parameters were observed between the different groups. None of the parameters correlated with the metoclopramide dose. Time pH < 4 expressed as the difference between day 1 and day 2, relative to day 1, decreased significantly as a function of C1h. No side effects were observed. A similar study should be performed after repeated dosing regimen.

Analysis of Variance↗
PubMed1993

Effects of endothelin on renal function in newborn rabbits.

The renal effects of endothelin-1 were investigated in 16 anesthetized and mechanically ventilated newborn rabbits. Renal blood flow and glomerular filtration rate were determined by the clearance of para-aminohippuric acid and inulin, respectively. Each animal acted as its own control. In eight newborn rabbits, a bolus injection of 5 nmol.kg-1 of endothelin-1 caused an initial fall in mean arterial blood pressure followed by a gradual, significant increase in mean arterial blood pressure that lasted for 45 min. The dramatic increase in renal vascular resistance (+28 +/- 4%) induced by endothelin led to a fall in glomerular filtration rate (-12 +/- 4%) and renal blood flow (-16 +/- 3%). In spite of the reduction of glomerular filtration rate and renal blood flow, urine flow and sodium excretion rates increased significantly (+20 +/- 5% and +49 +/- 9%, respectively). In eight additional newborn rabbits, a bolus injection of 1 nmol.kg-1 of endothelin--a dose that usually induces marked renal and systemic vasoconstriction in adult models--did not affect systemic or renal hemodynamics. In conclusion, endothelin induces renal and systemic vasoconstriction and affects water and sodium homeostasis during the neonatal period. These effects occur under higher doses than those used in adult animals. This age difference in systemic and renal responsiveness is probably mediated by receptor immaturity and/or interference of high levels of counteracting hormones present during the neonatal period.

Animals↗
PubMed1993

[Hemorrhagic shock with encephalopathy syndrome or major hyperthermia syndrome?].

A five month-old infant presented with gastro-intestinal symptoms followed by a multiple organ failure with: shock, status epilepticus, disseminated intravascular coagulation, hepatic and renal failure. The infant survived with major neurological sequelae. The diagnosis and the actuality of the so-called "hemorrhagic shock and encephalopathy syndrome" are discussed.

Brain Diseases↗
PubMed1992

Renal effects of dopamine and dopexamine in the newborn anesthetized rabbit.

The renal effects of dopexamine, a new dopaminergic agonist with marked beta 2-adrenergic agonist properties, but no alpha-adrenergic effect, has been studied in 8 newborn New Zealand rabbits, whose renal functional characteristics show close similarities with those of premature infants. Six animals were used as controls. After a control period, dopexamine was infused intravenously at a rate of 4 micrograms/kg per min and after a wash-out period, at 10 micrograms/kg per min. The renal effects of dopamine were studied in similar conditions. Glomerular filtration rate (GFR) and renal plasma flow (RPF) were determined by inulin and para-aminohippuric acid clearances, respectively. Dopexamine, 4 micrograms/kg per min, did not induce changes in cardiovascular and renal hemodynamics or in renal functions. At 10 micrograms/kg per min, a significant increase in urine flow rate (25 +/- 5%; p less than 0.01), urine sodium excretion (77 +/- 17%; p less than 0.01) and fractional sodium excretion (69 +/- 25%; p less than 0.05) was observed. The GFR, RPF and renal vascular resistance (RVR) were not affected. Heart rate increased slightly but significantly (8 +/- 3%; p less than 0.05), without change in mean blood pressure (MBP). Dopamine, 4 micrograms/kg per min, decreased slightly albeit significantly MBP (3 +/- 1%; p less than 0.05). At 10 micrograms/kg per min the only renal effect was a significant increase in RVR (19 +/- 6%; p less than 0.02). The different actions of these two dopaminergic agonists in this immature model could be explained by their respective ability to activate electively the adrenergic and dopaminergic peripheral receptors. The natriuretic and diuretic effect of dopexamine in normal immature rabbits, in the absence of changes in RPF or GFR is probably mediated by a direct action of this agent on dopaminergic tubular receptors. Failure of these two drugs to increase RPF may be related to an immaturity of the dopaminergic vascular receptors.

Adrenergic Agonists↗
PubMed1992

Vasodilators in persistent pulmonary hypertension of the newborn: a need for optimal appraisal of efficacy.

Tolazoline hydrochloride is usually the first choice pulmonary vasodilator in persistent pulmonary hypertension of the neonate (PPHN). The analysis of 26 articles including 467 tolazoline-treated infants has been hindered by many methodological drawbacks. Tolazoline has always been administered to infants suffering refractory hypoxemia, but, unfortunately, pulmonary hypertension has not usually been investigated. Moreover, 80% of the tolazoline-treated neonates had an underlying pulmonary parenchymal disease as a potential cause of severe hypoxemia. Noteworthy is that similar comments apply to all studies dealing with the use of other pulmonary vasodilators in PPHN. Pulsed Doppler echocardiography (PDE) should allow a qualitative and quantitative approach for PPHN and an analysis of both success and failure of vasodilator therapeutics. In the meantime, the use of PDE requires more intense investigation prior to wide application in PPHN.

Epoprostenol↗
PubMed1992

[Simultaneous recording of pH in the distal and proximal esophagus].

A 24 hour esophageal pH recording was performed in 46 infants (age: 10 +/- 12 months). Two probes were placed in the proximal and distal esophageal sites respectively. A significant correlation was shown between the upper and lower part of the esophagus for the numbers of acid (pH fall below 4 for at least 15 s) and weakly acid (fall in pH of more than one unit, irrespective of whether or not the pH fell below 4) gastroesophageal reflux (GER), the reflux index and the number of acid GER longer than 5 min. The number of acid GER and the time spent at pH less than 4 at the proximal esophagus were significantly greated in group 1 (reflux index greater than 5% in the distal esophagus, n = 10), than in group 2 (reflux index less than 5% in the distal esophagus, n = 36). The proportion of distal acid and weakly acid reflux reaching the upper esophagus presented with marked variation coefficients. These findings indicate that data obtained in the distal esophagus are poorly predictive of the results in the proximal esophagus, even if infants present high reflux index at the lower esophagus. Weakly acid GER reached the upper esophagus more frequently than acid GER.

Child, Preschool↗
PubMed1991

Vasoactive factors in the immature kidney.

The newborn infant is in a state of renal insufficiency with a glomerular filtration rate (GFR) as low as 20 ml/min per 1.73 m2 at term, and 10 ml/min per 1.73 m2 at 28 weeks of gestation. While the immature "insufficient" kidney can cope with most of the normal demands, its reserve is limited, and often overwhelmed by commonly occurring neonatal stresses. Various vasoactive systems such as the renin-angiotensin system, intrarenal adenosine, the prostaglandins and the atrial natriuretic peptide, are hyperactive in the neonatal period. Some of these systems appear crucial for the maintenance of GFR. Overstimulation of both angiotensin II and adenosine by an hypoxaemic stress can further impair the GFR, eventually leading to established renal failure. Inhibition of angiotensin II formation by the administration of angiotensin converting enzyme inhibitors can, on the other hand, also lead to renal failure. Prevention of these renal risks requires a precise knowledge of the newborn kidney physiology, physiopathology and pharmacology.

Adenosine↗
PubMed1991

Gastro-oesophageal reflux in mechanically ventilated preterm infants.

Long duration oesophageal pH recordings were performed on 42 mechanically ventilated and parenterally fed preterm infants for a mean (SD) of 94 (28) hours. Their mean (SD) gestational age was 31.5 (2.6) weeks and birth weight 1514 (448) g. Their mean postnatal age was 19 (10) hours at the onset of pH recording, which was performed with the babies supine. The mean hourly values for the total number of episodes of gastro-oesophageal reflux (GOR) was 2.3 (2.7), for acid GOR 1.2 (1.4), and for acid GOR longer than 5 minutes 0.08 (0.09). The time the pH was greater than 4 (the reflux index) was 3.5 (3.3)% and the mean airway pressure was 6.6 (5.1) cm H2O. Fifteen infants had a reflux index above 5%. GOR patterns were not significantly correlated to birth weight, gestational age, postconceptional age, ventilatory patterns, and duration of mechanical ventilation. We concluded that the reproducibility of the reflux index was low because the median of the absolute differences was 1% when two consecutive 12 hour periods were compared and reached 2.5% when the two periods were separated by 96 hours. A second 24 hour pH recording was performed in 30 of the 42 patients after weaning from the ventilator and at a time when patients were asymptomatic and enterally fed. Compared with the late postprandial period of the second pH recording, the first recording showed an increase in the number of episodes of GOR and a decrease in reflux index, without any difference in the number of episodes of acid GOR.

Esophagus↗