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G Jorch

Publications and source records attributed to G Jorch.

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

Modification of the open circuit N2 washout technique for measurement of functional residual capacity in premature infants.

We compared the standard nitrogen (N2) washout technique for measuring functional residual capacity (FRC) with a modified technique that uses a helium/oxygen mixture (heliox) at different ratio instead of pure oxygen. The tests were made with a standard lung function system equipped with an ultraviolet (UV) analyzer for measurement of N2 concentrations in the expired gas. We examined models of "spontaneous breathing" and "mechanical ventilation," each with volumes of FRC in the range of a premature and a newborn lung (20-80 ml), using both techniques at different baseline inspired oxygen concentrations (FIO2). Correlations between known and measured volumes were high and identical for the two techniques (r = 0.996), and the mean error was not significantly different from zero (P = 0.111). Measurements of FRC in 6 infants gave a correlation coefficient of r = 0.989 between the two techniques; reproducibility, as measured by the coefficient of variation, was high, showing no significant differences between both techniques (P = 0.792). However, values of individual infants were different (P = 0.011), and the slope of the regression line relating measurements by the 2 techniques was 1.04, with an intercept on the y-axis at 1.46. We conclude that FRC can be measured with the modified N2 washout technique, using heliox as a washout gas. Volumes can be measured with high precision and reproducibility, even in premature infants with low lung volumes and/or high baseline FIO2. A correction factor may be necessary to equate FRC measurements made by oxygen-N2 vs. heliox-N2 washouts. Hyperoxemia and hypoxemia can be avoided by admixing different flows of oxygen to a standard heliox mixture.

Calibration↗
PubMed1997

Epidemiological features of sudden infant death after a German intervention campaign in 1992.

UNLABELLED: After national intervention campaigns, considerable declines in incidence for both sudden infant death (SID) and prone position have been observed worldwide. In the following investigation. German data on postinterventional risk factor patterns are presented for the first time. We analysed data from a 2-year population-based case-control study on SID carried out in two German districts between 1993 and 1994. We confirmed Complete covering of the baby (OR = 44.9, 95%-CI 95, 291), prone sleeping position (OR = 11.7; 5.3, 26.2), heavy maternal smoking during pregnancy (OR = 8.5; 3.2, 33.2 for > ten cigarettes per day), nonbreastfeeding (OR = 7.7; 2.7, 22.3) and missing maternal professional training (OR = 7.6; 3.6, 16.2) as risk factors for cot death. After adjustment for other major risk factors in a logistic regression model, sleeping on cushions lost statistical significance, whereas all other major risk factors remained relevant. CONCLUSIONS: Despite intervention campaigns, complete covering of the baby, prone position and heavy maternal smoking are still major risk factors for cot death. Except for sleeping on cushions, all major epidemiological risk factors for cot death act independently. Despite encouraging success in the reduction of risk factors for cot death, there is still substantial need for future endeavours towards a further reduction of modifiable risk factors for SID.

Bedding and Linens↗
PubMed1997

Frequency dependence of cerebrovascular impedance in preterm neonates: a different view on critical closing pressure.

The nonproportional relationship between instantaneous arterial blood pressure (BP) and cerebral blood flow velocity (CBFv) is well explained by the concept of critical closing pressure (CCP). We aimed to determine the frequency response of the neonatal cerebrovascular system, and to establish the exact mathematical relationship between cerebrovascular impedance and CCP under physiologic conditions. In 10 preterm neonates (gestational age, 25-32 weeks; birth weight, 685-1,730 g; age 1-7 days) we Doppler-traced CBFv of the internal carotid artery. Blood pressure was traced simultaneously. Critical closing pressure was graphically determined. Cerebrovascular impedance was calculated as the square root of the ratio of the corresponding peaks in the power spectra of BP and CBFv at zero frequency, and at heart rate (H) and harmonics (xH). Uniformly, the impedance between H and 3H (2 to 6 Hz) was reduced about fivefold, compared with the impedance at zero frequency. The cerebrovascular system behaves like a high-pass filter, leading to a reduction of the DC (direct current) component of CBFv (analogous to current) relative to that of the driving force BP (analogous to voltage). The frequency response of cerebrovascular impedance reflects the ratio of CCP and DC BP. A mathematical derivation of this relationship is given matching the observed results. Thus, both the CCP and the impedance approach are valid.

Birth Weight↗
PubMed1997

Interactions between maternal smoking and other prenatal risk factors for sudden infant death syndrome (SIDS).

In numerous investigations, maternal smoking increases the risk of sudden infant death syndrome (SIDS). In the present study we investigated whether prenatal risk factors for SIDS modify the effect of maternal smoking on SIDS mortality. We analysed data from a population-based cohort study (222 cases, 260,604 infants at risk) within the Westphalian Perinatal Inquiry in Germany between 1990 and 1994. In the stratified analysis, smoking was classified into non-smoking, moderate (1-10 cigarettes/d) and heavy smoking (> 10 cigarettes/d). Multiplicative interactions between smoking and other prenatal risk factors were assessed in a logistic regression model. The relative risk (RR) for maternal smoking was 2.4 (95% confidence interval 1.7-5.4) for moderate and 7.2 (5.3, 9.7) for heavy smokers. Previous established risk factors for SIDS, such as preterm birth, low birthweight, and number of prenatal visits did not increase the risk of SIDS among non-smokers, but became important risk factors among smokers. In preterm infants (< 37 weeks) of heavy smokers, the RR was 19.6 (10.4, 36.8) compared to term infants of non-smokers. Low birthweight infants (< 2500 g) of heavy smokers had a RR of 16.3 (8.4, 31.2) compared to normal weighted infants of non-smokers. Adjustment for occupational status did not change the crude estimates. The RR of < 6 prenatal visits in the heavy smoking subgroup was 14.8 (7.2, 29.6) compared to > 9 prenatal visits in the non-smoking strata. Heavy smoking potentiates other prenatal risk factors for SIDS suggesting an increased susceptibility towards the adverse effects of tobacco smoke in utero. In infants born to non-smoking mothers, prenatal risk factors are absent and postnatal factors may be of major importance.

Birth Weight↗
PubMed1997

Cross-spectral analysis of cerebral autoregulation dynamics in high risk preterm infants during the perinatal period.

In preterm infants intraventricular hemorrhage occurs predominantly within the perinatal period, which may be due to a "lost autoregulation" of cerebral blood flow (CBF). In this study, perinatal autoregulation dynamics were investigated in high risk preterm infants by cross-spectral analysis (CSA), which is a statistical tool in the analysis of time series. In 15 ventilated preterm infants of 25-32 gestational weeks, a total number of 30 records were made between 24 and 96 h of life. Doppler-derived CBF velocity (CBFv), used as a quantitative measure for CBF, and direct mean arterial blood pressure (MABP) were measured continuously for 10 min. The spectral power of low frequency (LF, 0.02-0.2 Hz) oscillations in CBFv and MABP was quantified by spectral analysis. From the results of CSA, a LF phase-shift between the CBFv and MABP LF oscillations was calculated in each record. Within the study group, the LF spectral power of CBFv and MABP was initially low and increased significantly until 96 h of life. The LF phase-shift was about 0 degrees at 24 h and increased significantly to 55 degrees at 96 h of life. The initially low LF spectral power of CBFv and MABP may indicate a perinatal depression of autonomic nervous centers, which are thought to control LF oscillations of vital parameters. In the light of a high pass filter model for autoregulation, the initially low LF phase-shift may indicate an initially impaired autoregulation, which supports the "lost autoregulation" hypothesis.

Cerebrovascular Circulation↗
PubMed1996

Detection and significance of adenoviruses in cases of sudden infant death.

Respiratory tract infections have been thought to act as a trigger mechanism in sudden infant death. In 118 autopsy cases of infant death, paraffin-embedded or frozen lung tissues were investigated by means of a nested polymerase chain reaction (PCR) to detect adenovirus (AV) DNA. The primers used are general primers and allow the detection of most pathogenic adenoviruses with high specificity and sensitivity and independently of devitalization of viruses or degradation of viral DNA. For the investigation three groups were established: there were 13 cases of unnatural death, 78 cases of natural death without histological signs of interstitial pneumonia, and 27 cases with interstitial pneumonia. The first group was AV negative. In the group without interstitial pneumonia AV was detected in 10.2% of the cases. In the group with interstitial pneumonia the frequency of AV detection was almost 26%. The results obtained demonstrate an association between interstitial pneumonia and detection of AV DNA, indicating that AV may play an important part in pulmonary infection in infants. Histological evidence of interstitial pneumonia was not observed in all AV-positive cases, perhaps because nonspecific virus-related changes occurred only in early stages of viral infection. Comparison of the AV frequency in SIDS (25%) and non-SIDS cases (4%) indicates an association between pulmonary AV infections and sudden death. These results support the working hypothesis of respiratory infections acting as a trigger mechanism in sudden infant death.

Adenoviridae↗
PubMed1996

Left atrial thrombus in a 10-month-old boy--successful thrombolysis with recombinant tissue-type plasminogen activator after open-heart surgery: review of the literature.

A 10-month-old boy with major left atrial thrombus following cardiac surgery was treated with intravenously administered recombinant tissue-type plasminogen activator (rt-PA; Actilyse, Thomae-Behring, Germany). The left atrial thrombus was diagnosed by Doppler echocardiography 8 days after complete correction of a ventricular septal defect. rt-PA therapy was administered over a 10-day period. Significant hemopericardium occurred 50 h after the start of thrombolytic therapy. rt-PA infusion was discontinued for 20 h to insert a pericardial drainage. The initial rt-PA dose was 0.1 mg/kg over 10 min followed by a continuous daily infusion of 1.7 mg/kg together with low-dose heparin. Thrombolytic therapy was restarted 20 h after pericardial drainage was inserted. The daily rt-PA dose was gradually raised to 3 mg/kg (total dose: 18 mg/kg). On day 7 and 8 a clear decrease in P-plasminogen and P-antithrombin occurred, requiring additional fresh frozen plasma and P-antithrombin concentrate substitution. One day later, without further side effects, complete thrombolysis occurred. Although hemopericardium demanded discontinuation of thrombolytic therapy, rt-PA administration, closely monitored by Doppler echocardiography, was continued, leading to complete thrombolysis of the left atrial thrombus in the early postoperative period. We consider the literature dealing with rt-PA thrombolysis in infancy we discuss this case report.

Cardiac Surgical Procedures↗
PubMed1996

Are adult transcranial Doppler systems suitable for application in neonates?

UNLABELLED: Transcranial Doppler systems have not been available for monitoring of cerebral blood flow velocities in neonates because of potential hazardous effects of energy output from standard instruments developed for adult application. Aim of the study was to test commercially available transcranial Doppler instruments for their applicability in neonates and to develop guidelines for adaptation for safe neonatal use. Energy output of five commercially available transcranial Doppler instruments was measured with a hydrophone system and a radiation force balance. At the highest setting and at the nominal 10% attenuation level, five out of five and two out of five instruments, respectively, had an energy output above the recommended limits. Power reduction was not linear in one instrument. Evaluation of safety devices (alarm, freeze mode, energy reduction facilities, display of energy values) showed that none of the tested instruments had an optimal setting for safe neonatal application. CONCLUSION: Commercially available transcranial Doppler instruments should be evaluated critically for their energy output prior to their application in neonates. Special software for neonatal application of transcranial Doppler systems should be developed in order to provide extremely low energy output levels and devices for indication of duration of Doppler insonation and energy output.

Humans↗
PubMed1996

Effect of a reduced vitamin K supplementation on prothrombin time in prematures and high-risk neonates.

Recommendations for vitamin K supplementation were recently changed to 3 x 1 mg orally in healthy term neonates and 0.2 mg parenterally in prematures and high-risk neonates. Prothrombin times (PT) at reduced vitamin K doses (120 patients, 170 samples) during the first 6 weeks of life were below 40% in 6 patients only; all low PTs were unrelated to vitamin K. In the remaining patients, median PT was 100%; 79% of patients had values above 70%. PT was related to birthweight, gestational age and age. There was no decrease over the observation period. Following reduced oral and parenteral vitamin K regimens PTs were well within published reference values for neonates given larger amounts of vitamin K.

Administration, Oral↗
PubMed1995

Critical closing pressure in preterm neonates: towards a comprehensive model of cerebral autoregulation.

In preterm neonates, intraventricular haemorrhage is linked to the dysfunction of cerebral autoregulation (AR). We aimed at tracing the critical closing pressure (CCP) in order to quantify AR and to reveal its inner workings. In an observational study, 10 preterm neonates (median, range: ga 28 weeks, 25 to 32 weeks; bw 1070, 685 to 1730 g; age 2d, 1 to 7 d) were continuously Doppler traced (a. carotis interna) for > 10 min. Systemic blood pressure (BP, a. umbilicalis, a. radialis, a. temporalis) was recorded simultaneously (> 1200 cardiac cycles each). Systolic BP was on average 11 mmHg above CCP. There was a striking parallel between both variables, even in cases of sudden spontaneous BP fluctuations > 30% (r = 0.72, 0.41 to 0.99), while systolic cerebral blood flow velocity remained largely unaffected (r = -0.15, -0.75 to 0.53), indicating a properly functioning AR. CCP was 28 mmHg, 14 to 38 mmHg. Based on our data, a physiological model of AR is developed, integrating anatomy, metabolic and neuronal pathways with former physiologic findings--including low frequency cycling of cerebral blood flow velocity. Tracing of CCP is thought to have the potential to identify infants with impaired AR. Since this method is noninvasive and independent of angle of insonation (thus rendering it uncritical in probe fixation), it is a promising tool for sustained monitoring of cerebral haemadynamics in the clinical setting.

Blood Flow Velocity↗
PubMed1995

Impact on blood pressure and intestinal perfusion of dobutamine or dopamine in hypotensive preterm infants.

In a prospective study hemodynamic effects of dobutamine or dopamine (10 micrograms/kg/min) were investigated in 20 preterm infants who had protracted arterial hypotension refractory to volume therapy. Doppler ultrasonography of the superior mesenteric artery (SMA) was applied to verify intestinal perfusion and blood pressure was recorded in parallel. Mean arterial pressure (MAP) raised significantly in both groups (from 31.0 +/- 6.8 to 37.7 +/- 9.8 mm Hg during dobutamine and from 27.7 +/- 3.6 to 36.0 +/- 9.3 mm Hg during dopamine). Mean blood flow velocity increased from 25.8 +/- 13.5 to 31.5 +/- 16 cm/s with dobutamine and from 16.3 +/- 5.0 to 19.0 +/- 6.0 cm/s with dopamine (significant for dobutamine). Vascular resistance of SMA (indicated by resistance index; RI) decreased from 0.81 +/- 0.07 to 0.74 +/- 0.11 for dobutamine and from 0.89 +/- 0.06 to 0.79 +/- 0.07 for dopamine (significant for both groups). These data indicate that in the dose tested here both catecholamines are equally effective in raising MAP and lead to a significant increase of intestinal perfusion. Thus, a negative impact on mesenteric blood supply, predisposing to necrotizing enterocolitis, is not probable.

Blood Pressure↗
PubMed1995

[Causes of perinatal brain damage].

The incidence of cerebral palsy has remained constant at 2 per 1000 life births in western countries through cesarean section and electronic fetal monitoring have been applied increasingly often since the last decades. There has been a shift towards prenatal causes and consequences of early prematurity. High risk deliveries (3% of all) should be performed only in specialized centers for perinatal medicine. For low risk deliveries local hospitals are more convenient and are traditionally well accepted in Germany. Perinatal hypoxia as a cause of perinatal brain damage is rare. Documentation of clinical symptoms of hypoxic-ischemic encephalopathy is mandatory in these cases. To investigate regional risk factors of perinatal brain damage we propose to connect the data of the perinatal inquiries and of the examinations of preschool children directed by german law.

Asphyxia Neonatorum↗
PubMed1994

The effect of epoetin beta (recombinant human erythropoietin) on the need for transfusion in very-low-birth-weight infants. European Multicentre Erythropoietin Study Group.

BACKGROUND: Anemia of prematurity is characterized by low reticulocyte counts and inadequate erythropoietin response, for which many very-low-birth-weight infants receive multiple blood transfusions. We investigated whether early treatment of such infants with recombinant human erythropoietin would reduce their need for transfusions. METHODS: We performed a controlled, blinded trial in 241 infants with very low birth weights at 12 centers in six European countries. When three days old, the infants were randomly assigned either to the epoetin group or to the control group. Those in the epoetin group received 250 IU of epoetin beta per kilogram of body weight subcutaneously three times a week from day 3 to day 42 (for a total of 17 doses); those in the control group did not receive this drug. Infants in both groups received oral iron (2 mg per day) from day 14 onward. RESULTS: The control infants needed a mean of 1.25 transfusions each, as compared with 0.87 transfusion for epoetin-treated infants (P = 0.013). The median cumulative volume of blood transfused per kilogram per day was 0.41 ml in the control group (first quartile, 0 ml; third quartile, 0.8 ml) and 0.09 ml in the epoetin group (first quartile, 0 ml; third quartile, 0.8 ml) (P = 0.044). The rate of success, defined as an absence of need for transfusions and a hematocrit that never fell below 32 percent, was 4.1 percent in the control group and 27.5 percent in the epoetin group (P = 0.008). Epoetin was most beneficial in boys with birth weights of 1200 g or more and a base-line hematocrit of 48 percent or more. No toxic effects were observed in the epoetin group; as compared with the control group, the epoetin group had an increased incidence of septicemia (14 vs. 7 episodes, P not significant) and reduced weight gain (520 vs. 571 g, P = 0.02). CONCLUSIONS: Infants with very low birth weights have less need of transfusions if given epoetin beta during the first six weeks of life (250 IU per kilogram three times a week). We recommend early epoetin treatment for all such infants, but further studies of nutrition and iron supplementation during treatment are needed.

Anemia, Neonatal↗
PubMed1994

Cyclic variation pattern of cerebral blood flow velocity and postconceptional age.

In preterm neonates, the risk for intracerebral haemorrhage is linked to immaturity of cerebral autoregulation. The preterm's 2-5/min cyclic variation pattern of cerebral blood flow velocity is thought to reflect the degree of immaturity of autoregulation--a speculation to be tested. In a cross-sectional study 15 infants (gestational age 26-40 weeks, postconceptional age (PCA) 26-42 weeks, age 1-99 days were investigated. We performed a 10 min pulsed Doppler tracing on an internal carotid artery by means of a computer controlled 5 MHz Duplex device. Systolic velocity (Vs) was recorded pulse by pulse. After appropriate data transformation, in all infants the Fast Fourier Transform of the time course of Vs revealed the presence of a 2-5/min cyclic variation pattern (one sample z-test, P < 0.0001). There was no significant correlation between proportionate spectral power of the 2-5/min frequency band and either PCA (r = 0.23, P = 0.42) or age (r = 0.41, P = 0.13). Between 26 and 42 weeks PCA, the cycling phenomenon is constant thus not reflecting cerebral maturation, and its presence does not mean immaturity of cerebral autoregulation.

Age Factors↗
PubMed1994

High-dose versus low-dose bovine surfactant treatment in very premature infants.

The aim of the study was to determine if high-dose bovine surfactant (Alveofact, initially 100 mg/kg birth weight) would improve oxygenation compared with low-dose surfactant (50 mg/kg birth weight) administered intratracheally within 1 h after birth. Inclusion criteria included gestational age 24-29 weeks and birth weight 500-1500 g, intubation and mechanical ventilation, absence of congenital malformations and bacterial infections. Retreatment was considered if the fraction of inspired oxygen (FiO2) was > 0.4 (dose 50 mg/kg birth weight). The primary endpoint was level of oxygenation (PaO2/FiO2) 2 h after treatment. The study design was a sequential analysis using a triangular test with alpha = 0.05 and 95% power to detect a 25% improvement in the endpoint. Oxygenation was improved significantly with high-dose (n = 42) compared to low-dose treatment (n = 48): 30.9 +/- 15.0 kPa (231.5 +/- 112.7 mmHg) versus 24.1 +/- 15.7 kPa (180.6 +/- 118.0 mmHg) (mean +/- SD). The survival rate was 83% in both groups and the incidence of pulmonary interstitial emphysema was 33% versus 14% with the high-dose treatment. We conclude that high-dose surfactant significantly improved oxygenation and reduced lung barotrauma. An initial dose greater than 50 mg/kg birth weight of surfactant is required for optimal acute response.

Dose-Response Relationship, Drug↗
PubMed1994

Cerebral autoregulation of preterm neonates--a non-linear control system?

The low frequency cerebral blood flow velocity (CBFV) oscillations in neonates are commonly attributed to an under-dampened immature linear type cerebral autoregulation, and the 'instability' is regarded as causative for peri-intraventricular haemorrhage/periventricular leukomalacia. In contrast, oscillations susceptible to frequency entrainment are a fundamental part of the stable function of non-linear control systems. To classify the autoregulation an observational study was done on the relationship between CBFV oscillations, heart rate variability, and artificial ventilation. In 10 preterm neonates (gestational age 26 to 35 weeks) we serially Doppler traced arterial CBFV continuously for 12 minutes between days 1 and 49 of life. The individual time series of CBFV and heart rate were subjected to spectral analysis. Forty six of 47 tracings showed significant low frequency CBFV oscillations. Low frequency heart rate oscillations were not a prerequisite thereof. All patients with < 30% of total power in the low frequency band of CBFV oscillations were on the ventilator. Three of them demonstrated a shift of spectral power from low frequency to a frequency equal or harmonic to the ventilator rate indicating entrainment. The findings of CBFV oscillations combined with entrainment classify the autoregulation as a non-linear system. It is suggested that entrainment by periodic high amplitude stimuli might challenge the regulatory capacity to its limits thus increasing the risk for cerebral damage.

Blood Flow Velocity↗