Biomedical subjects
Publications and source records attributed to G Jorch.
Treatment with bovine surfactant (SF-RI 1) was shown to be efficacious in improving pulmonary function and in increasing survival rate without BPD in very premature infants. Surfactant therapy did not affect the risk of major complications of prematurity.
To investigate changes of intracerebral blood flow velocity correlated to different behavioural states, pulsed Doppler measurements were performed on anterior cerebral artery in 12 preterm and term neonates under polygraphic recordings and in view of the infants' behavioural state. Under very strict definition of the behavioural states there were significant differences in the parameters Vm (+25%), Vd (+75%), and Vs (+11%) in active compared to quiet sleep state. MABP was not significantly different in all examined behavioural states. From our results we conclude that in further Doppler studies the infants' behavioural state at the time of measurement should be assessed carefully.
Doppler-ultrasonography measures blood flow velocity, which is proportional to blood flow if the vessel's diameters remain constant. Perfusion of brain, kidneys and gut can thus be estimated by transcutaneous ultrasonography at specific locations on the internal-carotid artery, renal artery and upper mesenteric artery. Cardiac output can be derived from measurements taken on the ascending aorta. The procedures of measurement are easy to learn, but interpretation is more critical. Doppler-ultrasonography has been applied in persistent ductus arteriosus, asphyxia, hyperventilation, brain death, impact of drugs on brain circulation, seizures, hydrocephalus, and shock. Future aims are the development of miniaturized doppler-sensors with low energy output for continuous monitoring, and the definition of guidelines for clinical applications.
Blood flow velocities and pulsatory indices in both renal arteries (RAs) and in the internal carotid artery (CAI) were measured by pulsed Doppler ultrasonography in ten preterm infants with patent ductus arteriosus (PDA), before and after surgical ligation. The results obtained in the RAs were compared to those found in a reference group of 22 stable preterm infants. In the RAs the diastolic steal volume of the PDA led to a marked decrease in diastolic blood flow velocity (range 3 to -23 cm/s). Seven infants showed retrograde diastolic flow, whereas only three infants had these flow patterns in the CAI. In the RAs, the peak systolic blood flow velocities (range 56 to 135 cm/s) exceeded the values found in the reference group by 85% on average. The pulsatility indices reached values of above 1,00. In spite of the increase in systolic flow velocities before surgery, the time mean of maximum velocities was significantly lower than those measured after surgery and in the reference group. After PDA ligation, blood flow velocities normalized. The present study shows that a large PDA may induce abnormal flow patterns even in the RAs. These flow patterns may predispose to renal hypoperfusion and subsequent impairment of renal function.
As a part of a multicentre clinical trial of prophylactic treatment with bovine surfactant (SF-RI 1) given to immature infants below 31 gestational weeks, short term and protracted effects on cerebral haemodynamics were assessed by Dopplersonographic measurements of the right internal carotid artery. Measurements were performed every 10 min for 1 h after intratracheal application of the surfactant in ten treated infants. The results of additional measurements every 12 h up to the age of 100 h were compared with a control group. In single cases there were changes of time averaged mean maximum velocity (Vmax) of as much as 100% immediately after intratracheal surfactant application, although the mean short term and protracted variability of Vmax was the same as the protracted variability in the control group. Variability of mean arterial blood pressure and transcutaneous carbondioxide tension (tcpCO2) was even less. With proper adjustment of ventilatory settings intratracheal treatment with surfactant does not affect variability or absolute values of internal carotid Vmax, mean arterial blood pressure and transcutaneous pCO2 in low birth weight infants within 100 h after application.
This paper presents the range of normal blood flow velocity in different cerebral veins in early infancy measured by transfontanelle pulsed Doppler ultrasonography. The blood flow velocity of the internal jugular vein (38 infants), internal cerebral vein (28 infants), and straight sinus (18 infants) in a group of clinically stable neonates and young infants (body weight 1060-3750 g, age 1-86 d, gestational age 28-41 wk) is specified. The time mean of maximum velocity (Vma) of internal jugular vein was 8.4 +/- 4.7 cm/s, of internal cerebral vein 5.5 +/- 1.6 cm/s, and of straight sinus 12.6 +/- 7.8 cm/s. While the variability between infants was high, the reproducibility of the method was in the range of 4.4-10.2% for Vma. This compares well with studies on cerebral arteries and offers a noninvasive approach to the study of the venous cerebral hemodynamics in neonates undergoing intensive care.
In contrast to adult humans and animals, so far there are no studies in infancy on the effects of halothane and isoflurane on cerebral hemodynamics. We used transfontanellar Doppler ultrasonography to close this gap. In the study we looked at changes of Vmax as a measure of changes in cerebral blood flow. In 10 infants (4.7 +/- 1.0 kg BW) Vmax decreased 5 min after anesthetic induction with halothane 1.5% at 33%, and in a comparable group of 10 infants (5.3 +/- 1.2 kg BW) 5 min after anesthetic induction with an equipotential dose of isoflurane 2.5% at 28%. In 4 infants there was even a retrograde diastolic flow under anesthetic induction. This decrease was so far never seen in adults, in whom halothane increases cerebral blood flow and isoflurane has only little effect.
Studies on the side effects of diazepam on the particularly vulnerable brain of preterm infants have not been done so far. We studied changes of blood flow velocity in the anterior, basilar and internal carotid artery by Doppler technique in 11 preterm infants less than 1,500 g who were given 0.5 mg/kg i.v. diazepam. The flow velocities in the internal carotid and basilar artery did not change significantly and values for carbon dioxide tension, mean arterial blood pressure and HF remained stable. There was a marked increase of flow velocity in the anterior cerebral artery. We conclude that diazepam in this dosage does not cause dangerous haemodynamic changes in the premature brain.
The case of an 8-year-old boy is reported, who developed acute pulmonary edema associated with acute subglottic swelling and subsequent partial upper airway obstruction after extubation and recovery from anaesthesia. The main factors responsible for the formation of pulmonary edema presumably are a large subatmospheric transpulmonary pressure gradient and hypoxia leading to translocation of circulating blood volume into the pulmonary vasculature and fluid shift across the alveolar-capillary membrane. Application of oxygen and CPAP or PEEP plus diuretic therapy will promote rapid clearance of the pulmonary edema.
So far, echo-Doppler studies of the renal arteries have only been performed in adult subjects. They dealt with qualitative parameters of blood flow, but absolute velocity values could not be determined. This paper presents a method for measurement of absolute values of renal artery blood flow velocity in infancy with a well-defined steep angle of insonation of less than 25 degrees by using a range-gated Doppler system with Duplex-scan. The renal blood flow patterns were studied at specified sites by placement of the transducer below the costal arches on the right flank and left flank, respectively. Thus, a reference collective of 65 infants (26-40 weeks of gestational age, 650-3990 g body weight and 1-145 days of postnatal age at the time of examination) were studied. The time mean of maximum velocity significantly increased with the body weight from 17 cm/s below 1000 g to 29 cm/s above 3000 g of body weight. Whereas the pulsatility indices were independent of body weight. The reproducibility of the method, coefficient of variation (CV) 3%-9%, is comparable with the studies of cerebral vessels.
In very premature ventilated infants (GA 25-30 weeks, BW 575-1420 g) values for heart frequency, mean arterial blood pressure and pCO2 were obtained, and also Doppler-sonographic measurements of the right internal carotid artery were performed to assess cerebral haemodynamics, before and 5-10 min after the intravenous injection of 20 mg/kg phenobarbitone (study I/n = 10) or 5 mg/kg phenobarbitone (study II/n = 10). There were no significant changes in any of these parameters. Therefore phenobarbitone does not have seem to have any significant effect on cerebral haemodynamics up to a dosage of 20 mg/kg, so that there is no apparent effect on the risk of cerebral haemorrhage. On the other hand this study confirms that phenobarbitone can be used in very low birth weight preterm infants with this dosage without causing any substantial haemodynamic risk.
To reveal the influence of therapeutically induced changes of arterial blood pressure on cerebral circulation, pulsed Doppler measurements of blood velocity in the right internal carotid artery were performed in 23 neonates. A positive correlation between mean arterial blood pressure and time-averaged maximum blood velocity (change more than 0.5%/torr) could be noticed in 16 infants. These infants were supposed to have loss of autoregulation. The main characteristics in this non-autoregulating group were: gestational age less than 31 weeks, birth weight less than 1501 g and mean carotid blood velocity less than 20 cm/s. In accordance with animal experiments we assume that autoregulation does not work below a definite lower limit of brain perfusion, which is reflected by carotid blood velocity in our study. Patients below/equal 1500 g or 30 gestational weeks very often do not exceed this limit and thus do not reach the "range of autoregulation".
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Changes of blood velocity in the right internal carotid artery (measured by transfontanellar pulsed Doppler) in relation to therapeutically induced changes of mean arterial blood pressure (measured oscillometrically) were used to evaluate autoregulatory capacity of cerebral blood flow in 17 neonates (540-3800 g). Preterm infants less than 32 gestational weeks (n = 11) didn't autoregulate, while the capacity of autoregulation was significantly better in neonates greater than 31 gestational weeks (n = 6). Regarding their disturbed autoregulation there was no difference between normotensive (n = 4) and hypotensive (n = 7) preterm infants less than 32 gestational weeks.
A series of 57 tracheotomies in infants and children was subdivided into two categories. Group A consisted of patients who primarily suffered from severe obstruction of the upper airway. The results demonstrated that tracheotomy was an effective procedure in handling these cases. 30 patients were placed into group B. In this series the upper airway was primarily not involved. Considering the severe cardiac, central and nephrogenic underlying diseases tracheotomy did not play a significant role in the healing process except in few cases. Patients in group B had a higher complication rate and death rate than those in group A. Altogether two patients died because of tracheotomy-related complications (haemorrhage and displacement of cannula). For decreasing the complication rate proper surgical technique and regular endoscopic controls are necessary. "pro and contra" of tracheotomies in children are discussed.
We describe a three-year-old boy with clinical findings of infectious mononucleosis, but no serologic proof in the beginning of his disease. The subsequent course was complicated by fatal pulmonary complications compatible with an adult respiratory distress syndrome (ARDS). Repeat serologic tests for Epstein-Barr virus finally could confirm the diagnosis of infectious mononucleosis. Thus, ARDS has to be added to the possible rare causes of fulminant, fatal cases of infectious mononucleosis.
This paper describes our method to evaluate neonatal cerebral circulation in a semiquantitative way by transfontanellar pulsed Doppler ultrasonography. We defined three arterial (internal carotid, basilar, and anterior cerebral artery) and three venous (internal cerebral and internal jugular vein; sinus rectus) sites for measurement of peak systolic, end diastolic, and mean velocity. Reference values, intraindividual and interindividual variation are calculated for infants between 750 and 4000 g body weight. Among all possible measurements follow up of mean velocity of the internal carotid artery in an individual infant is most reliable.
Range-gated pulsed Doppler-ultrasonographic blood flow measurements of 3 cerebral arteries (a. cerebri anterior, a. carotis interna, a. basilaris) were performed during acute pCO2-changes in 16 neonates treated in an intensive care unit. Pulsatility index, peak systolic and end diastolic flow velocity, and mean velocity were evaluated. Mean velocity in the a. carotis interna and the a. basilaris depends on the pCO2, and increases resp. decreases by 5.6% per mm Hg of rise resp. fall of the pCO2. Assuming no pCO2-dependent diameter changes of the large cerebral arteries volume flow would increase resp. decrease by a proportional amount. When obtaining qualitative or semiquantitative informations about volume flow by Doppler-ultrasonography anatomic conditions must be considered carefully.