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Biomedical subjects

G Krim

Publications and source records attributed to G Krim.

At least 19 recordsLinked to original sources
PubMed1998

Determination of diffusing capacity by modeling the dynamics of C18O uptake in newborns.

Dynamic modeling of lung C18O diffusion is used to measure the C18O transfer factor (TLCO) of 14 newborns aged 1-4 mo. The model equation is based on the alveolar fractions of C18O and on changing alveolar ventilation induced by the rebreathing conditions. The model does not involve the volume of the rebreathing bag which is usually needed when applying rebreathing technique and which is a source of error. The equation is discretized and solved for recorded data obtained with equipment adapted to use in newborns. A least-square parameter calculation technique is applied to estimate TLCO. Results show a strong relationship between this index and the biometrical ones and confirm those found in the literature featuring that the measurement duration can be considerably shortened.

Analysis of Variance↗
PubMed1998

Reproducibility of the alternating breath test of fractional inspired O2 in infants.

We conducted a reproducibility study of the alternating breath test (ABT) for assessing peripheral chemoreceptor function in infants. The ABT delivers a rapid hypoxic stimulus to the peripheral chemoreceptors with breath-by-breath alternations of the inspired O2 fraction. The reproducibility of the ABT performed on a single occasion has not been extensively studied in infants. Eight unsedated infants (postnatal age, 22+/-19 d; weight, 3.2+/-0.4 kg) were studied in standardized conditions: morning naps, supine position, room temperature 22-24 degrees C, quiet sleep, and face mask attached to a pneumotachograph connected to a two-way electric valve. Respiratory gases were analyzed by mass spectrometer. Two ABTs were performed. Each included a 2-min control run (CR) alternating between air and air, and a 2-min test run (TR) alternating between air and 0.15 O2. After data preprocessing, on average 13+/-11% of the data were rejected because of sighs, apneas, and cycles with the fraction of inspired oxygen above 0.17. Using the remaining validated breaths, the response to ABT was calculated for the CR, for all breaths in the TR (TR(T)), and for the first 50 breaths of the TR (TR50). During the ABTs oxygen saturation did not fall below 96%, and heart rate was not affected. Inspired and end-tidal CO2 fractions remained unchanged during the ABTs. FetO2 oscillated in TRs at a lower values than in CRs and differed significantly between breaths of air and hypoxic breaths of TRs. All infants responded to ABT with percentage alternation coefficients of TRs significantly greater than those of CRs for all respiratory variables. The values of the coefficients were not significantly different between both ABT, and between TR50 and TR(T). The greatest values of the coefficients were for timing variables compared with flows and volume. We conclude that the ABT is a reproducible test of peripheral chemoreceptor function under standardized conditions.

Breath Tests↗
PubMed1997

Consequences of a small decrease of air temperature from thermal equilibrium on thermoregulation in sleeping neonates.

A new heating unit (servocontrolled skin temperature derivative system) has been designed to control the thermal environment in closed incubators. This type of control acts to attain and closely maintain a thermal equilibrium between a neonate's skin temperature and the environment. The present study aims to discover if thermal equilibrium is located within a thermoneutral range defined from oxygen consumption VO2 and body temperature, and whether it is more appropriate to define an optimal thermal environment. As regards VO2 and body temperature, results show that the air temperature reached at thermal equilibrium fulfils the definition of thermoneutrality. According to these criteria, a small decrease (1:5 degrees C) from thermal equilibrium also provides a near thermoneutral environment to the neonate but induces sleep disturbances and an increase in body movements. These two additional parameters delineate a narrower thermoneutral zone than does minimal metabolic rate because VO2 can stay constant even when air and body temperatures decrease. The results suggest that thermal equilibrium might be assimilated with a thermal comfort zone.

Automation↗
PubMed1997

Skin derivative control of thermal environment in a closed incubator.

Defining a thermoneutral environment remains difficult because thermoneutrality depends on both physical and physiological factors. A servocontrolled skin temperature derivative (SCS) heating device has been designed to control the thermal environment in closed incubators without the necessity of setting an air or skin reference temperature. The thermal environment obtained with the SCS program is controlled only by the neonate's skin temperature changes. For each neonate, the program allows the attainment of a specific individual thermal equilibrium (Teq). Although the mean value of the thermal equilibrium level measured on 29 neonates does not differ significantly from the neutral air temperature defined from the charts of other researchers, individual values of Teq differed greatly among neonates of similar birthweight and postnatal age. When compared with on/off heating programs, the SCS system permits greater quiet sleep occurrence and seems to provide an optimal thermal environment. The results suggest that the skin temperature derivative heating program takes into account both the ambient and physiological factors affecting body temperature regulation of each neonate.

Automation↗
PubMed1996

[Evolution of the result of respiratory function studies in children with bronchopulmonary dysplasia].

BACKGROUND: Reports of short- and medium-term evolution of Lung Function Tests (LFT) in infants with bronchopulmonary dysplasia (BPD) are still scarce. POPULATION AND METHODS: The results of the first (before 3 months of corrected age) and the second (between 3 and 9 months of corrected age) LFT in 22 premature infants with BPD (gestational age 31 +/- 2.5 weeks; birth weight: 1570 +/- 440 g; duration of mechanical ventilation: 46 +/- 24 days, total duration of oxygen therapy: 88 +/- 47 days) were compared to those obtained in 27 normal infants for the first LEF and 10 normal infants for the second LFT, similar to the patients for birth weight and corporeal index (CI). RESULTS: In the first LFT, major abnormalities were an increased thoracic gaz volume (TGV) (16.5 +/- 42 vs 122 +/- 24 mL; P < 0.001) and TGV CI ratio (1.25 +/- 0.31 vs 0.89 +/- 0.17 ml/kg/m2; P < 0.0001) a decreased pulmonary compliance (2.49 +/- 1.46 vs 11.60 +/- 4.50 mL/cmH2O; P < 0.0001) and specific pulmonary compliance (0.015 +/- 0.10 vs 0.100 +/- 0.042 mL/cmH2O/mL de TGV; P < 0.0001), an increased total pulmonary resistance (20.4 +/- 12.1 vs 10.5 +/- 5.3 cmH2O/L/s; P < 0.001). In the second LFT, an increased TGV (235 +/- 62 vs 166 +/- 28 mL; P < 0.01) and TGV CI ratio (1.64 +/- 0.65 vs 0.98 +/- 0.11 ml/kg/m2; P < 0.05), a decreased pulmonary compliance (2.68 +/- 2.0 vs 15.2 +/- 5.7 mL/cmH2O; P < 0.0001) and specific pulmonary compliance (0.013 +/- 0.010 vs 0.106 +/- 0.050 mL/cmH2O/mL de TGV; P < 0.0001), an increased total pulmonary resistance (17.1 +/- 9.6 vs 8.6 +/- 4.9 cmH2O/L/s; P < 0.05) were noted when compared with the control group results. Major abnormalities of the blood gases were hypoxemia (63 +/- 10 vs 85 +/- 20 mmHg; P < 0.05), hypercapnia (38.5 vs 31 +/- 4 mmHg; P < 0.0001) during the first LFT. Hypoxemia (77 +/- 14 vs 90 +/- 14 mmHg and hypercapnia (37 +/- 4 vs 29 +/- 5 mmHg) continued in the second LFT. Thoracic distention and total pulmonary resistances in infants with BPD did not improve but their pulmonary compliance (P < 0.0001) and PaO2 (P < 0.01) between the first and second LFT did it. Infants who had been ventilated for a hyaline membrane disease (HMD) were more hypoxic on the second LFT (P < 0.05) than those who had been ventilated for other causes. Statistically significant relationships were found between thoracic distention and duration of positive inspiratory pressure (P < 0.05; r = 0.43), duration of positive expiratory pressure (P < 0.05, r = 0.45) total oxygen therapy duration; between total pulmonary resistance and duration of mechanical ventilation with high frequency (P < 0.05; r = 0.52); between hypoxemia and duration of oxygen therapy with FiO2 > or = 60% (P < 0.05; r = 0.54). CONCLUSIONS: This study shows prolonged clinical and functional abnormalities of the respiratory functions requiring longer follow-up.

Blood Gas Analysis↗
PubMed1996

Body temperature regulation in the newborn infant: interaction with sleep and clinical implications.

Thermoregulation in newborn infant differs from that of adult. Comparisons between sleep stages show that, during rapid eye movements (REM) sleep, the impairment of thermoregulatory responses in adult is not observed in newborn. Both behavioral and autonomic temperature regulations are always operative in the range of air temperatures usually imposed. The interaction between sleep and thermoregulation seems to be less important in newborns than in adults, suggesting that sleep processes are well protected, reducing the probability of occurrence of central dysfunction. According to the model describing thermoregulation during sleep on the basis of changes in the hierarchical dominance of brain structures, either the influence of diencephalic structures is never depressed in REM sleep or the functional autonomy of the rhombencephalon is still relevant in the immature encephalon of the newborn. The thermoregulatory model also allows understanding of inter-individual differences in thermoregulation and levels of thermoneutrality. An attempt has also been made to learn the role of heat stroke in the production of sudden infant death syndrome when body heat loss is hampered.

Adaptation, Physiological↗
PubMed1995

[Retrospective analysis of 1331 samples of cerebrospinal fluid in newborn infants with suspected infection].

BACKGROUND: Definitive diagnosis of a neonatal infection usually requires recovery of an etiologic agent from body fluids or tissues such as spinal fluid, blood and urine. Routine lumbar puncture (LP) may raise some problems in interpreting results. POPULATION AND METHODS: A retrospective analysis of 1331 samples of CSF was made. LP had been performed on 1041 neonates including 569 prematures (54.6%) as a part of the evaluation for suspected bacterial infection. RESULTS: In 50.7% of the cases, the CSF was haemorrhagic. The frequency of traumatic taps increased with the degree of prematurity, low birth weight, precocity of LP, association with respiratory distress and disorders of coagulating factors. In addition, haemorragic taps modified biochemical and cytologic characteristics of CSF. One hundred and six (8%) CSF samples contained organisms but the diagnosis of meningitis was certain in only 23 cases (2.2%). In the other 83 cases, CSF was thought to be contaminated, mostly by coagulase-negative staphylococci. Since both blood and CSF cultures were positive for the same bacterial organism in 18 cases, it was concluded that the LP had been useful in identifying the pathogens in only five cases. The high frequency of contaminated CSF led to overestimation of the incidence of true bacterial meningitis (0.57% in our study). CONCLUSIONS: The low incidence of meningitis in neonates, the risk of having an haemorragic tap associated with the possibility of clinical aggravation during LP and the fact that the same pathogen is frequently (78.2% of cases) identified in blood cultures suggest that the immediate and routine LP is of less value than expected in infants suspected to be infected. LP could be postponed when the neonate presents with a respiratory distress syndrome and/or a precarious haemodynamic state.

Bacterial Infections↗
PubMed1990

[Standardization of oculo-cardiac reflex in infants under 3 months of age].

The authors present a standardization of the oculocardiac reflex carried out in early-age infants (under 3 months). This standardization is easy to perform. It takes into account the fall of the cardiac frequency, the asystoly and the range of bradycardia until its normalisation. Thus, it allows inter or intra individual comparison and can be applied to the study of infants at risk for sudden infant death syndrome.

Humans↗
PubMed1989

[Epiglottitis and pulmonary edema in children].

A case of acute epiglottitis complicated by pulmonary edema, after intubation in a 30 month-old child is reported. The pathophysiology of this complication and its treatment associating oxygen therapy and positive end expiratory pressure are discussed.

Child↗
PubMed1989

[Marfan disease presenting in neonates with rapid cardio-vascular failure. Apropos of 2 cases].

We report two exceedingly unusual and severe cases of Marfan syndrome with neonatal manifestations. Clinical features were caricatural. The skin was of the cutis laxa type. Both infants died shortly after birth as a result of severe cardiovascular lesions. Histologic examination of the aortic media confirmed the diagnosis. Because this genetic connective tissue dysplasia is inherited on an autosomal dominant basis with strong penetrance, and because in both instances the two parents had a negative family history, a dominant mutation seems likely in our cases and prompted us to be optimistic when giving genetic counseling. We point out the characteristic features of these exceptional early forms and describe the results of a detailed histologic examination of the skin that completes data from the literature.

Aorta↗
PubMed1989

[Treatment of acute renal failure by continuous hemofiltration in newborn infants and infants].

During acute oligoanuric renal failure in neonates and infants, arteriovenous or veno-venous continuous hemofiltration is a simple, useful technique when peritoneal dialysis or hemodialysis cannot be used. It allows fluid removal, optimal calorie intake and mild blood purification, when waiting for diuresis to stabilize. It does not give any control over hypercatabolism; the use of continuous dialysis increases epuration.

Acute Kidney Injury↗