Biomedical subjects

C E Blanco

Publications and source records attributed to C E Blanco.

At least 73 records · Page 4Linked to original sources

PubMed1997

Use of neonatal intensive care unit as a safe place for neonatal surgery.

AIM: To evaluate the advantages, disadvantages, and short term morbidity and mortality of major surgical interventions performed in the neonatal intensive care unit. METHODS: A retrospective case review of 45 neonates was performed from April 1991 to September 1995. The characteristics of the patients were: gestational age 29 (SD 4) weeks (range 24 to 41 weeks); birth-weight 1305 (870) g (range 540 to 4040 g); presurgical weight 1430 (895) g (range 550 to 4370 g); postconceptional age at surgery 31 (4) weeks (26 to 47 weeks). The indications for surgery were: ligation of patent ductus arteriosus (n = 16); insertion of a subcutaneous ventricular catheter reservoir for hydrocephalus (n = 14); repair of congenital diaphragmatic hernia (n = 2); open lung biopsy (n = 1); and laparotomies (because of necrotising enterocolitis, anorectal malformations, and intestinal obstructions) (n = 12). The management of these neonates at laparotomy was: bowel resection with stomas (n = 8) and stomas (n = 4). No specially designed area was used to perform surgery. RESULTS: Local or systemic infection associated with surgery was not seen and no perioperative mortality was related to the surgical procedure. CONCLUSIONS: The neonatal intensive care unit is suitable for major surgery during the neonatal period and no special area is needed to perform complication free surgery.

Evaluation Studies as Topic↗

PubMed1997

The effect of hypercapnia and hypercapnia associated with central cooling on breathing in unanesthetized fetal lambs.

In utero breathing activity is present periodically, but it must become continuous at birth. We investigated the effect of hypercapnia and of hypercapnia combined with central cooling on fetal breathing in seven chronically instrumented fetal lambs of 131-134-d gestation, using an extracorporeal membrane oxygenation (ECMO) system to control fetal blood gases and fetal temperature. During fetal hypercapnia (from a partial pressure of arterial CO2 (Paco2) 6.18 +/- 0.11 kPa to Paco2 7.39 +/- 0.15 kPa) frequency, amplitude, and incidence of fetal breathing movements during low voltage electrocortical activity (LV ECoG) increased significantly compared with isocapnic control on ECMO, but breathing remained absent during high voltage electrocortical activity (HV ECoG). During hypercapnia accompanied by central cooling (Paco2 7.90 +/- 0.13 kPa, temperature decreased by 2.1 degrees C) there were similar changes in fetal breathing movements during LV ECoG, but in four out of seven fetuses fetal breathing movements continued throughout HV ECoG. Hypercapnia accompanied by central cooling can thus override the inhibitory effects of HV ECoG on fetal breathing movements. This may be due to changes in sensitivity to CO2 produced by an increase in afferent input to the CNS.

Animals↗

PubMed1997

Initiation and maintenance of continuous breathing at birth.

Changes in arterial PCO2 (PaCO2) and body temperature normally occurring at the moment of birth may play a role in the initiation and maintenance of continuous breathing. To clarify these mechanisms, five chronically instrumented fetal lambs were connected to an extracorporeal membrane oxygenation (ECMO) system. ECMO was initiated in utero at a flow rate sufficient to support the fetus totally, the umbilical cord was occluded, and the fetuses were delivered into a warm isotonic saline bath. Breathing activity was present periodically before connection to the ECMO system and on ECMO during fetal normocapnia and normoxia. Near delivery there were no breathing movements, because all ewes were in labor. After delivering the fetuses into the warm saline bath, breathing movements remained episodic, being absent during high voltage electrocortical activity, whereas fetal PaCO2 remained constant. However, after 36-192 min, breathing activity became present continuously in all animals, at a time when fetal central temperature decreased. Once initiated, continuous breathing could be stopped by reducing the PaCO2. We conclude that maintenance of fetal PaCO2 and a slow decrease in central temperature after cord occlusion delays the establishment of continuous breathing, and that the level of PaCO2 is important in the maintenance of breathing activity during early postnatal life.

Animals↗

PubMed1997

Changes in mean chorioallantoic artery blood flow and heart rate produced by hypoxia in the developing chick embryo.

Hypoxia in the mammalian fetus produces cardiovascular changes, such as bradycardia, systemic hypertension, and changes in heart rate variability. This response was studied in 140 chick embryos ranging from stage 34 to stage 42 (d 9-16 of the 21-d incubation), by measuring the changes in mean chorioallantoic artery blood flow (CABF) and heart rate for 5 min in two levels of hypoxia (group 1; n = 90; 100% N2) or (group 2; n = 50; 5% O2). Eggs were opened at the air cell and placed in a small plexiglass holder, which had a continuous gas flow of an O2/N2 mixture (5 L/min), at 38 degrees C and 60% humidity. The chorioallantoic artery was placed in the lumen of a flow probe to measure mean CABF, heart rate, peak flow, and blood flow acceleration. After baseline measurements, the gas mixture was changed to 100% N2 or 5% O2 in N2 for 5 min. Mean CABF and heart rate decreased significantly in both groups (Wilcoxon paired sample test, p < 0.05). This response was more pronounced with the development of the chick embryo. Chorioallantoic artery peak flow (mL/min) and CABF acceleration (mL/s2) increased with incubation time and decreased during periods of hypoxia. During recovery, heart rate returned to baseline levels, whereas mean CABF showed an overshoot. The initial decrease in mean CABF and heart rate was similar in both groups. The cardiovascular response to hypoxia in the chick embryo is similar to the response in the mammalian fetus. The more pronounced response in the more developed chick embryo may represent a maturation of cardiovascular control.

Allantois↗

PubMed1997

Frequency shift of individual spontaneous otoacoustic emissions in preterm infants.

In adults, spontaneous otoacoustic emissions (SOAE) have shown a considerable frequency stability. In preterm infants, however, the SOAE proved to show an apparent and consistent upward shift of frequency at increasing postconceptional age (PCA). In 25 ears of 14 preterm infants (PCA, 29.1-41.3 wk) a total of 66 SOAE frequencies were monitored, ranging from 1611 to 5774 Hz. All but one of the SOAE frequencies shifted toward higher frequency. The SOAE frequency shift rate in Hertz per week was proportionally constant relative to the SOAE frequency. The mean shift rate was 0.74 +/- 0.39%/wk. At increasing PCA, the SOAE frequency shift rate tended to slow down. A linear fit through the data predicted the SOAE frequency to stop at about 45-50-wk PCA. The frequency dependence and time course of the SOAE frequency shift strongly suggest cochlear maturation during the last period of gestation.

Acoustic Stimulation↗

PubMed1997

Mixed venous oxygen saturation and biochemical parameters of hypoxia during progressive hypoxemia in 10- to 14-day-old piglets.

In this study we wanted to assess the relationship between mixed venous oxygen saturation (SVO2) and tissue oxygenation. For that, we compared the values of SVO2 with oxygen delivery (DO2), oxygen consumption (VO2), and markers of tissue hypoxia such as lactate and pyruvate during progressive hypoxemia. Eight 10-14-d-old piglets were anesthetized, tracheotomized, intubated, and ventilated. A fiberoptic catheter was placed in the carotid artery to monitor arterial oxygen saturation (SaO2). A thoracotomy was performed, and a fiberoptic catheter was placed in the pulmonary artery to monitor SVO2. A transit time ultrasound flow probe was positioned around the ascending aorta to measure aorta flow. Progressive graded hypoxemia was induced by decreasing fractional inspiratory oxygen concentration (FIO2) from 1.0 to 0.30, 0.21, 0.15, and 0.10. After each FIO2 interval blood samples were taken for blood gases, lactate, and pyruvate. DO2 and VO2 were calculated. SVO2 decreased similarly to SaO2. A value of SVO2 of more than 40% excluded oxygen restricted metabolism. When DO2 decreased below a critical range (8.4-12.8 mL/kg x min), SVO2 decreased below 15%, and lactate and the lactate/pyruvate ratio increased. We conclude 1) that baseline SVO2 values excluded oxygen-restricted metabolism, 2) that SVO2 values between 15 and 40% were not a marker for oxygen-restricted metabolism, and 3) that SVO2 values below 15% were associated with oxygen-restricted metabolism. Reduced SVO2 values must be interpreted as a change of the factors that determine the balance between DO2 and VO2 and as a warning that, with further reduction of SVO2, oxygen restricted metabolism can develop.

Animals↗

PubMed1996

Treatment of respiratory failure due to respiratory syncytial virus pneumonia with natural surfactant.

We describe two infants suffering from severe pneumonia caused by respiratory syncytial virus (RSV) infection and needing mechanical ventilation with both high ventilator settings and a high fraction of inspired oxygen. The severity of the respiratory failure and the possibility of decreased and/or altered surfactant production led us to treat these infants with intratracheal instillation of natural surfactant. This resulted in an improvement of lung compliance and a decrease in the amount of oxygen required to maintain acceptable oxygen saturations. Intratracheal surfactant instillation might, therefore, be useful in the treatment of severe RSV pneumonia.

Humans↗

PubMed1996

The influence of acute hypoxemia and hypovolemic hypotension of neuronal brain activity measured by the cerebral function monitor in newborn piglets.

Little is known about the cerebral electrical response to short periods of hypoxemia, hypotension and their combination. These conditions occur frequently in critically ill newborn infants; their cerebral electrical activity can be registrated easily with the Cerebral Function Monitor (CFM). Therefore we recorded on-line cortical electrical activity during hypoxemia and hypotension in 11 newborn piglets aged 13-18 days. Hypoxemia was induced by reducing inspired oxygen fraction. Hypotension was induced by withdrawal of blood. The experimental groups were: Group I: arterial oxygen saturation (SaO2) 45-85%, group II: SaO2 < 45%, group III: mean arterial pressure (MAP) 50-75 mmHg, group IV: MAP < 50 mmHG, group V: SAO2 < 85% and MAP 50-75 mmHg and group VI: SaO2 < 85% and MAP < 50 mmHg. CFM registrated normal cortical electrical activity during periods of moderate or severe hypoxemia (group I and II) and during isolated moderate hypotension (group III). The cortical activity decreased significantly due to severe hypotension alone (group IV) and combined hypotension and hypoxemia (group V and VI). Hypotension has a more potent effect on cortical electrical activity than hypoxemia in the newborn piglet. Cerebral electrical activity does not change during severe hypoxemia and moderate hypotension possibly due to cerebral flow regulation. CFM recorded decreased cerebral electrical activity during severe hypotension and hypotension with hypoxemia. CFM could provide invaluable data in severely ill newborns.

Animals↗

PubMed1996

Influence of feeding artificial-formula milks containing docosahexaenoic and arachidonic acids on the postnatal long-chain polyunsaturated fatty acid status of healthy preterm infants.

In view of the importance of long-chain polyunsaturated fatty acids (LCP) for growth and development of fetal and infant neural tissue, the influence of the dietary n-3 and n-6 LCP intake on the LCP status of forty-three preterm infants (birth weight < 1800 g) was studied. Thirty-one formula-fed infants were randomly assigned to receive a conventional formula lacking LCP (n 16), or an 22:6n-3- and 20:4n-6-enriched formula (n 15); twelve infants received their own mother's breast milk. Fatty acid compositions of plasma and erythrocyte (RBC) phospholipids (PL) were determined in umbilical venous blood, in weekly postnatal samples until day 35 of life and, for the formula-fed infants, at 3 months of corrected age. Both in plasma (P < 0.001) and RBC (P < 0.01) PL, the changes with time until day 35 for 22:6n-3 and 20:4n-6 in the two groups of formula-fed infants were significantly different, with higher values, comparable with those of human-milk-fed infants, in the LCP-enriched-formula group. At 3 months of corrected age, differences between the two formula-fed groups were even more pronounced. In conclusion, adding 22:6n-3 and 20:4n-6 to artificial formulas in balanced ratios and in amounts similar to those found in preterm human milk raises both the 22:6n-3 and the 20:4n-6 status of formulated preterm infants to values found for human-milk-fed preterm infants. Additional studies are necessary to evaluate the potentially favourable effects of this combined addition on the neurodevelopmental outcome of preterm infants.

Arachidonic Acids↗

PubMed1996

Continuous central venous oxygen saturation (ScvO2) measurement using a fibre optic catheter in newborn infants.

AIMS: To describe the range of central venous oxygen saturation (ScvO2) values in stable newborn infants breathing room air; to examine the correlation between ScvO2 and arterial oxygen saturation (SaO2); to describe fractional oxygen extraction; and the shunt index, an estimate of the venous admixture. METHODS: A prospective clinical observational study was made of 10 preterm infants breathing room air after the acute phase of respiratory distress syndrome, and with an umbilical venous catheter in situ. A fibre optic catheter remained in the right atrium for continuous measurement of oxygen saturation. RESULTS: ScvO2, SaO2, blood pressure and heart rate were registered every 15 minutes. Fractional oxygen extraction and shunt index were calculated. SaO2 and ScvO2 were 93.4 (SD 3.7)% and 73.56 (5.25)%, respectively. In seven patients ScvO2 values correlated significantly with SaO2. Fractional oxygen extraction was 0.21 (0.04) and was significantly correlated with ScvO2. The shunt index was 24% (12) and was significantly correlated with SaO2. CONCLUSIONS: Stable preterm infants breathing room air had an ScvO2 ranging from 65% to 82% (5th and 95th percentile), which corresponded to SaO2 > or = 86%. ScvO2 values were significantly correlated with SaO2 in most patients.

Blood Gas Analysis↗

PubMed1996

Myosin phenotype and SDH enzyme variability among motor unit fibers.

Motor units in cat diaphragm and tibialis posterior muscles were classified physiologically as slow-twitch, fast-twitch, fatigue-resistant, fast-twitch fatigue-intermediate, or fast-twitch fatigable. Motor unit fibers were then identified by glycogen depletion and classified as type I, IIa, IIb, or IIx on the basis of myofibrillar adenosinetriphosphatase-staining profiles and immunoreactivity for myosin heavy-chain (MHC) isoforms. In both muscles, slow-twitch and fast-twitch fatigue-resistant units comprised type I and IIa fibers expressing MHC-slow and MHC-2A isoforms, respectively. Fast-twitch fatigue-intermediate and fast-twitch fatigable units comprised type IIx fibers expressing the MHC-2X isoform. Some fast-twitch fatigue-intermediate units had a mixed composition with a few fibers (approximately 10%) expressing the MHC-2A isoform. Motor unit fiber succinate dehydrogenase (SDH) activity was quantified, and variability was estimated by the interquartile range, which was lower among motor unit fibers than in adjacent fibers of the same histochemical type but comparable to that along the length of individual fibers. We conclude that, despite the mixed-MHC phenotype of some diaphragm and tibialis posterior motor units, SDH activity is relatively uniform. This supports the hypothesis that motoneurons exert a predominant influence on muscle fiber SDH activity.

Animals↗

PubMed1996

The chorioallantoic artery blood flow of the chick embryo from stage 34 to 43.

Chorioallantoic artery blood flow and heart rate were studied in the chick embryo from stage 34 until stage 43 (d 9-16 of 21-d incubation). Baseline blood flow profiles of the chorioallantoic artery were measured with a flow probe (Transonic) in 100 chick embryos. The eggs were opened at the air cell and placed in a small plexiglass box with a continuous gas flow of a N2/O2 mixture (5 L/min), at 38 degrees C and 60% humidity. The chorioallantoic artery was localized near the fetal abdomen and placed in the lumen of the Transonic flow probe. The heart rate was derived from the blood flow signal. The mean chorioallantoic artery blood flow rose from 0.35 +/- 0.14 mL/min (mean +/- SD) at stage 34 to 3.13 +/- 1.49 mL/min at stage 43 (R2 = 0.69, p < 0.0001), which correlated with an increase in body weight (1.51 +/- 0.18 g to 15.08 +/- 0.76 g). Heart rate increased from 195 +/- 38 beats/min at stage 34 to 289 +/- 13 beats/min at stage 43 (R2 = 0.38, p < 0.0001). The chorioallantoic artery blood flow, which in avian species correlates with umbilical blood flow in mammals, increased with incubation time as reported in the mammalian fetus. This study shows that the chick embryo could be useful as a preparation for further perinatal cardiovascular research.

Allantois↗

PubMed1995

Comparison between the essential fatty acid status of preterm and full-term infants, measured in umbilical vessel walls.

The essential fatty acid (EFA) composition of umbilical vessel walls is increasingly being studied as a longer-term reflection of the fetal EFA status. We evaluated the EFA content of umbilical artery and vein vessel walls in 43 preterm infants and compared it with that of 43 full-term cord vessels. In addition, relations among cord vessel wall fatty acid composition, gestational age (GA) at birth, and anthropometric parameters at birth (weight, head circumference, and length) were explored in the preterm infants. Generally, n-6 and n-3 EFA levels were lower, while levels of EFA deficiency markers were higher in preterm than in term cords, both in the walls of the draining arteries and the supplying vein. In preterm cords, significant correlations were observed between GA at birth and levels of n-6 and n-3 EFAs (positive) and EFA deficiency markers (negative). Birth weight showed significant (P < or = 0.01), positive correlations with n-6 and n-3 EFA levels in the cord artery walls of preterm infants, all after correction for GA at birth. In conclusion, substantial differences between the EFA profiles of preterm and full-term cord vessel walls indicate a lower biochemical EFA status of the preterm than of the term fetus. This lower preterm EFA status might be a reflection of a physiologically lower EFA demand for growth and development of the preterm fetus than of the term fetus.

Fatty Acids, Essential↗

PubMed1995

Long-chain polyunsaturated fatty acids in preterm infants: status at birth and its influence on postnatal levels.

To determine the influence of the prenatal long-chain polyunsaturated fatty acid (LCP) supply on prenatal growth and on postnatal LCP levels, we studied 52 preterm infants and assessed the relations between the LCP status at birth (reflecting the prenatal LCP supply), gestational age and prenatal growth, and the relation between the LCP status at birth and at 37 to 42 weeks of gestational age. After a correction for gestational age at birth, significant relations (p < or = 0.05) were observed between anthropometric measurements at birth (weight, head circumference, and length) and LCP levels in the umbilical artery wall, the LCP content of which reflects the long-term fetal LCP status. Independent of the neonatal diet (human milk or formula), LCP levels in erythrocyte phospholipids at term were positively related to levels in the umbilical artery wall (docosahexaenoic acid (22:6n-3): p < or = 0.0003; arachidonic acid (20:4n-6): p = 0.02). Postnatal diet significantly influenced LCP levels in plasma phospholipids at term (docosahexaenoic acid: p < or = 0.004; arachidonic acid: p = 0.02); formula-fed infants had lower values. We conclude that the LCP status of preterm infants at birth is related to prenatal growth. Moreover, next to the postnatal enteral diet, the LCP status at birth significantly affects LCP levels at term postconceptional age. This finding may warrant further studies of the effects of essential fatty acid-enriched maternal diets during pregnancy on the neonatal LCP status at birth.

Anthropometry↗

PubMed1995

Long-chain polyene status of preterm infants with regard to the fatty acid composition of their diet: comparison between absolute and relative fatty acid levels in plasma and erythrocyte phospholipids.

The long-chain polyene (LCP) status of thirty-nine premature infants (birth weight < 1800 g) was evaluated. Twenty-seven infants were fed on an artificial formula, twelve received their own mother's breast milk. Fatty acid compositions of both plasma and erythrocyte (RBC) phospholipids (PL) were determined in umbilical venous blood and in weekly postnatal blood samples until the 28th day of life. Individual fatty acid levels were expressed as absolute quantities (mg fatty acid/l plasma or RBC suspension) and as relative (mg/100 mg total fatty acids) values. The changes with time in the absolute values for 22:6n-3 and 20:4n-6 in plasma were strikingly different from those of the relative values for these fatty acids. In plasma PL the inter-group differences in the absolute postnatal values for 22:6n-3 (P < 0.0005) and 20:4n-6 (P < 0.05) and the relative values for 22:6n-3 (P < 0.02) were significant, with lower fatty acid values in the formula-fed infants. In RBC PL, no significant inter-group differences in the postnatal 22:6n-3 and 20:4n-6 values were found. Based on the assumption that it is desirable for formula-fed infants to achieve postnatal plasma LCP values at least comparable with those found in infants fed on human milk, the findings of the present study indicate that both n-3 and n-6 LCP should be added to preterm infant formulas. Moreover, the additional importance of absolute fatty acid levels was demonstrated, although analytical procedures need to be standardized to enable effective comparison of results from different research groups.

Dietary Fats↗

PubMed1995

Feasibility and accuracy of a fiberoptic catheter for measurement of venous oxygen saturation in newborn infants.

The current parameters of oxygenation, arterial oxygen saturation and arterial oxygen pressure represent the availability of oxygen to the tissues. Venous oxygen saturation reflects oxygen extraction and could be a more useful indicator of tissue oxygenation. Therefore, we tested the feasibility and accuracy of a fiberoptic catheter, inserted into the right atrium via the umbilical vein, to measure venous oxygen saturation continuously. In 24 of 36 (67%) infants the catheter could be placed into the right atrium. Blood samples were withdrawn through the catheter, analyzed with a hemoximeter and compared with simultaneously recorded oximeter values. The fiberoptic catheter readings correlated significantly with hemoximeter values and the mean difference of the 116 paired samples was -0.37%. We conclude that the success rate and complications of the fiberoptic catheter were similar to previously published results. The oxygen saturation readings accurately represented oxygen saturation in the right atrium in newborn infants.

Blood Gas Analysis↗

PubMed1995

Succinate dehydrogenase activity of sexually dimorphic muscles of rats.

Muscles of the male rat perineum attaching to the penis are the ischiocavernosus, the medial bulbocavernosus (BC), and the dorsal BC, also known as the levator ani (LA). The BC and the LA muscles are innervated by a morphologically, neurochemically, and physiologically homogeneous pool of motoneurons, the spinal nucleus of BC (SNB). The purpose of the present study was to determine whether BC and LA muscle fibers constitute histochemically and biochemically homogeneous populations, reflecting the homogeneity of the innervating motoneuron pool. Histochemical fiber type was based on the pH lability of myofibrillar adenosinetriphosphatase. Activity of the mitochondrial enzyme succinate dehydrogenase (SDH) was determined by using a quantitative histochemical procedure. A nonsexually dimorphic, androgen-insensitive muscle, the medial gastrocnemius (MG), was used as control. The superficial regions of the MG, BC, and LA muscles were composed exclusively of type IIb muscle fibers, whereas the fiber type composition of the deep region of the MG was mixed: 28.3% type I, 20.6% type IIa, 40.1% type IIx, and 11.0% type IIb. The SDH activities of type IIb fibers in the deep region of the MG ranged from 1.20 to 9.00 (mean 3.72 +/- 0.40) mmol fumarate.liter tissue-1.min-1. Fiber SDH activities in the superficial region of the MG ranged from 0.04 to 2.70 (mean 1.20 +/- 0.21) mmol fumarate.liter tissue-1.min-1. In the BC muscle, the SDH activities of the type IIb fibers ranged from undetectable to 1.80 with a mean of 0.62 +/- 0.05 mmol fumarate.liter tissue-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Perfluorochemical liquid ventilation: from the animal laboratory to the intensive care unit.

Perfluorochemical or perfluorocarbon liquids have an enormous gas-carrying capacity. During tidal liquid ventilation the respiratory medium of both functional residual capacity and tidal volume is replaced by neat perfluorocarbon liquid. Tidal liquid ventilation is characterized by convective and diffusive limitations, but offers the advantage of preserved functional residual capacity, high compliance and improved ventilation-perfusion matching. During partial liquid ventilation only the functional residual capacity is replaced by perfluorocarbon liquid. Both tidal and partial liquid ventilation improve gas exchange and lung mechanics in hyaline membrane disease, adult respiratory distress models and meconium aspiration. Compared to gas ventilation, there is less histologic evidence of barotrauma after liquid ventilation. Cardio-pulmonary interaction, inherent to the high density of liquid, and long term safety need further study. However, extrapolating from animal data, and taking into account promising human pilot studies, liquid ventilation has the desired properties to occupy an important place in the therapy of restrictive lung disease in man.

Animals↗