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Biomedical subjects

H Schiffmann

Publications and source records attributed to H Schiffmann.

14 recordsLinked to original sources
PubMed2001

Non-invasive radiation-free monitoring of regional lung ventilation in critically ill infants.

OBJECTIVE: Established techniques used to examine lung function in critically ill infants cannot continuously follow regional aspects of lung ventilation although this information would be beneficial for proper therapy planning. We have studied the applicability and clinical relevance of a relatively new non-invasive radiation-free imaging method, electrical impedance tomography (EIT), in monitoring regional lung function in paediatric intensive care patients. DESIGN: Prospective study. SETTING: Neonatal and paediatric intensive care unit (ICU) at a university hospital. PATIENTS: Eight infants (1 day-7 years old) suffering from miscellaneous diseases requiring intensive care therapy. INTERVENTIONS: Adjustment of ventilator settings, surfactant administration, and postural changes. MEASUREMENTS AND RESULTS: Repeated EIT measurements were performed with the intention to monitor regional lung ventilation in mechanically ventilated and spontaneously breathing infants. The follow-up time ranged between 1 and 11 days. During individual EIT measurements of 100-s duration electrical voltages resulting from repetitive injection of small electrical currents were continuously measured on the thoracic circumference using conventional surface electrodes. Acquired data were used to generate functional cross-sectional thoracic images of regional lung ventilation. A total of 638 EIT measurements were performed. The redistribution of lung ventilation and changes in regional ventilation magnitude resulting from adjusted positive end-expiratory pressure, peak inspiratory pressure, inspiration-expiration ratio, surfactant instillation, and prone or supine positioning were identified. CONCLUSIONS: Provided that EIT hardware and software are further developed to guarantee stable and undisturbed measurements in the ICU and that practical handling is improved, this non-invasive method may become a useful bedside monitoring tool of regional lung ventilation in critically ill infants.

Child↗
PubMed2001

Effects of epinephrine on the myocardial performance and haemodynamics of the isolated rat heart during moderate hypothermia--importance of calcium homeostasis.

Controversies exist concerning myocardial performance in hypothermia. We have studied the effects of epinephrine on myocardial function at various calcium concentrations in moderate hypothermia (28 degrees C) and normothermia (37 degrees C) using an isolated antegrade perfused rat heart. The maximum pressure velocity (dP/dt(max)) developed was significantly higher in normothermia compared with hypothermia and was improved by the addition of calcium in both circumstances. Peak negative pressure velocity (dP/dt(min)) was significantly higher at 37 degrees C compared with 28 degrees C, and was increased by the addition of calcium in normothermia; in contrast to hypothermia, in which no change of dP/dt(min) was observed. A reduction in cardiac output and stroke volume by hypercalcaemia was observed in hypothermia. The addition of epinephrine improved dP/dt(max) and dP/dt(min), but had a depressive effect on stroke volume and cardiac output at normal and elevated calcium concentrations. Myocardial efficiency was significantly higher during hypothermia compared with normothermia, but was impaired by epinephrine during hypothermia. The variable or even paradoxical effects of epinephrine suggest the need for careful haemodynamic monitoring and determination of calcium levels in hypothermia. The impairment of myocardial performance may be explained by impaired diastolic relaxation and calcium overload.

Animals↗
PubMed1999

Monitoring regional lung ventilation by functional electrical impedance tomography during assisted ventilation.

A new approach in discriminating the regional air volume changes in the lungs associated with either spontaneous or mechanical ventilation during assisted ventilation is presented. Impedance data are obtained by conventional electrical impedance tomography (EIT). The data are filtered in the range of either the spontaneous or the ventilator rate and processed by the functional EIT (f-EIT) evaluation technique, whereby the variation of the respective EIT data with time is determined and imaged. EIT measurements performed in an infant during synchronized intermittent mandatory ventilation were evaluated with this method and indicated that the specific local lung volume swings related to spontaneous and mechanical inhalations can be separated and imaged as tomograms. This noninvasive approach may become useful in optimizing the ventilatory pattern during advanced forms of artificial ventilation and may help the clinician in the therapy management of individual patients.

Blood Gas Analysis↗
PubMed1999

Determination of airway humidification in high-frequency oscillatory ventilation using an artificial neonatal lung model. Comparison of a heated humidifier and a heat and moisture exchanger.

OBJECTIVE: Thus far only few data are available on airway humidification during high-frequency oscillatory ventilation (HFOV). Therefore, we studied the performance and efficiency of a heated humidifier (HH) and a heat and moisture exchanger (HME) in HFOV using an artificial lung model. METHODS: Experiments were performed with a pediatric high-frequency oscillatory ventilator. The artificial lung contained a sponge saturated with water to simulate evaporation and was placed in an incubator heated to 37 degrees C to prevent condensation. The airway humidity was measured using a capacitive humidity sensor. The water loss of the lung model was determined gravimetrically. RESULTS: The water loss of the lung model varied between 2.14 and 3.1 g/h during active humidification; it was 2.85 g/h with passive humidification and 7.56 g/h without humidification. The humidity at the tube connector varied between 34. 2 and 42.5 mg/l, depending on the temperature of the HH and the ventilator setting during active humidification, and between 37 and 39.9 mg/l with passive humidification. CONCLUSION: In general, HH and HME are suitable devices for airway humidification in HFOV. The performance of the ventilator was not significantly influenced by the mode of humidification. However, the adequacy of humidification and safety of the HME remains to be demonstrated in clinical practice.

Artificial Organs↗
PubMed1997

Airway humidification in mechanically ventilated neonates and infants: a comparative study of a heat and moisture exchanger vs. a heated humidifier using a new fast-response capacitive humidity sensor.

OBJECTIVE: To study the efficiency of a heated humidifier and a heat and moisture exchanger in mechanically ventilated neonates and infants. DESIGN: Prospective, controlled, clinical study. SETTING: University pediatric intensive care unit. PATIENTS: Forty neonates and infants who needed mechanical ventilation were enrolled in the study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A heat and moisture exchanger and active airway humidification were alternately used in the same patients to exclude interindividual differences in airway humidification. Airway humidity was measured by a new fast-response capacitive humidity sensor which measures airway humidity with an acquisition rate of 20 Hz throughout the respiratory cycle. The humidity sensor was placed at the endotracheal tube adapter. Measurements were done at the beginning and at the end of three consecutive sessions of passive, active, and again passive airway humidification, each session lasting 6 hrs. There was no significant difference between mean inspiratory airway humidity with the heated humidifier (33.8 +/- 2.9 mg/L) and with the heat and moisture exchanger (34.0 +/- 2.6 mg/L). Moreover, the mode of airway humidification did not significantly influence body temperature or PCO2. No serious side effects such as endotracheal tube occlusion were observed. CONCLUSIONS: Passive airway humidification by a heat and moisture exchanger is effective in mechanically ventilated neonates and infants over a 6-hr period. However, the performance and safety of a heat and moisture exchanger in prolonged mechanical ventilation remain to be proven.

Costs and Cost Analysis↗
PubMed1995

Randomized, controlled trial of amoxicillin prophylaxis for prevention of catheter-related infections in newborn infants with central venous silicone elastomer catheters.

OBJECTIVE: To clarify the effectiveness of amoxicillin prophylaxis in the prevention of catheter-related infections. METHOD: We performed a randomized, controlled, sequential, prospective trial in newborn infants undergoing percutaneous central venous catheterization. RESULTS: Seventy-five infants (median birth weight, 1240 gm; median age at catheter insertion, 3 days) received prophylactic amoxicillin (100 mg/kg per day); 73 infants in the control group (median birth weight, 1170 gm; median age, 2 days) received no routine prophylactic antibiotic treatment. No infant receiving amoxicillin had septicemia, whereas two infants (2.7%) in the control group did; suspected septicemia (positive clinical and laboratory findings but negative blood culture results) was found in 3 infants in the amoxicillin group and in 6 of the control group (not significantly). Bacterial contamination of the catheter tip at removal was significantly reduced in the amoxicillin group (13.3% vs 28.8% in control subjects; p < 0.05). Negligible differences were found in duration of catheterization (median, 15 days in both groups), or the number of thrombotic (9.3% vs 2.7% in control subjects) and other catheter-related complications between the groups. CONCLUSION: A low incidence of catheter-related infections can be achieved in neonates with central venous catheters without using prophylaxis with an antibiotic.

Amoxicillin↗
PubMedDate not supplied

Amiodarone in a newborn with ventricular tachycardia and an intracardiac tumor: adjusting the dose according to an individualized dosing regimen.

We report the successful management of recurrent ventricular tachycardias in a newborn suffering from an intracardiac tumor. Amiodarone was the only agent able to control the tachycardias and did so as long as an individually titrated plasma concentration above 0.8 mu mol/L was maintained. Because no therapeutic plasma concentration has been defined in children and no kinetic studies are available in this population, we optimized the dosing regimen based on a computer simulation, taking into account the pharmacokinetic parameters of the patient and the individual concentration-effect relation.

Amiodarone↗
PubMedDate not supplied

[Lysis of cytostatic drug-associated axillary vein thrombosis].

A 3 years old patient receiving chemotherapy for acute-lymphoblastic leukemia according to the ALL-BFM 90-treatment protocol developed thrombosis of the vena axillaris. Without removing the central venous catheter located at the site of thrombosis it was possible to lyse the thrombus by the systemic application of recombinant human tissue-type plasminogen activator (rt-PA). The method is recommended for the treatment of thrombotic occlusions in children.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

[Importance of pre- and perinatal risk factors in respiratory distress syndrome of premature infants. A logical regression analysis of 1100 cases].

BACKGROUND: Respiratory distress syndrome (RDS) due to surfactant deficiency remains a cause of considerable mortality in the neonatal period. METHODS: In a retrospective study we analysed the records of 1109 premature newborns with a birth weight below 1500 g that were treated on our unit. RDS was assumed if the infants needed mechanical ventilation with oxygen supplementation and the typical radiological signs were present on chest x-ray. RESULTS: No changes in the incidence of RDS were found during the period of observation. Below 29 weeks gestational age 90% of infants suffered from RDS (55% severe RDS grade III or IV). The incidence was 75% (grade III or IV: 32%) for infants born at 29 and 30 weeks, 48% (grade III or IV: 15%) at 31 and 32 weeks and 33% (grade III or IV: 6%) for neonates born at 33 weeks of gestation. Using a logistic regression analysis model the following parameters were found to increase the risk for RDS significantly (p < 0.05): no prenatal steroid treatment, Cesarean section, male gender, APGAR at 5 min < 7, metabolic acidosis (base excess < or = -6 mval) and rectal temperature < 36 degrees C on admission. Following gestosis, insufficiency of the placenta and premature rupture of membranes a decrease in the incidence of RDS was observed. CONCLUSION: We conclude that although some risk factors for RDS will be difficult to exclude (e.g. maternal disease, gender) the incidence and severity of RDS can be reduced by measures like maternal antenatal steroid treatment. Perinatal asphyxia (low APGAR values and/or acidosis) and hypothermia should be avoided, as these conditions increase the relative risk for developing RDS.

Acidosis↗