Intracranial pressure and cerebral blood flow velocity in preterm infants with posthaemorrhagic ventricular dilatation.

AIM: To determine the volume of cerebrospinal fluid (CSF) that should be tapped in preterm infants with posthaemorrhagic ventricular dilatation as guided by intracranial pressure (ICP) and cerebral blood flow velocity (CBFV). METHODS: The total number of measurements was 106 in 22 infants. Birth weights ranged from 630 to 2050 g, gestational age from 24.5 to 30.3 weeks, and age at insertion from 12 to 67 days. A subcutaneous ventricular catheter reservoir for repetitive CSF drainage was placed when the diameter of a ventricle was > 4 mm above the 97th centile. A volume of 5 ml/kg body weight was removed twice daily. ICP and CBFV were determined before and after CSF tapping. RESULTS: If the ICP after tapping exceeded 7 cm H(2)O, tapping did not result in a significant improvement in CBFV. If the ICP before tapping was less than 6 cm H(2)O, tapping also had no effect on CBFV. Longitudinal studies in individual infants showed a slight correlation between ICP and CBFV. CONCLUSION: Volume of repetitive CSF drainage in preterm infants with posthaemorrhagic ventricular dilatation guided by ICP and CBFV may be a useful technique. An ICP of about 6 cm H(2)O is the cut off point for CSF drainage.

Relationship between mixed venous oxygen saturation and markers of tissue oxygenation in progressive hypoxic hypoxia and in isovolemic anemic hypoxia in 8- to 12-day-old piglets.

OBJECTIVE: To examine the hypothesis that mixed venous oxygen saturation (SvO2) values, which reflect the residual oxygen after tissue oxygen extraction, would be similar during hypoxic and anemic hypoxia. DESIGN: SvO2 values, oxygen delivery, arterial oxygen content, and fractional oxygen extraction were compared, and critical values were determined based on lactate, the lactate/pyruvate ratio, and oxygen consumption during hypoxic and anemic hypoxia. SETTING: Laboratory of physiology at a university hospital. SUBJECTS: Two groups of eight piglets, 8 to 12 days old. INTERVENTIONS: Piglets were anesthetized, tracheotomized, intubated, and ventilated. 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 hypoxic hypoxia was induced by decreasing FI(O2) from baseline (0.30-0.75) to 0.21, 0.15, and 0.10. Progressive anemic hypoxia was induced by a repeated isovolemic exchange transfusion with 50 mL of pasteurized plasma. MEASUREMENTS AND MAIN RESULTS: Fifteen or 30 mins after each intervention, samples were taken from the carotid artery for blood gases, hemoglobin, lactate, and pyruvate and from the pulmonary artery for blood gases and hemoglobin. Hemodynamic, arterial oxygen saturation, and SvO2 measurements were made. The calculated oxygen delivery and oxygen consumption decreased in both hypoxic and anemic hypoxia. At the lowest oxygen delivery level of anemic hypoxia, the decrease in SvO2 was less than that in hypoxic hypoxia (-26% vs. -55%). The range of critical values for SvO2 calculated for each individual piglet below which lactate, the lactate/pyruvate ratio, and oxygen consumption rapidly changed from baseline value was significantly lower in hypoxic hypoxia (11% to 24%) than in anemic hypoxia (26% to 48%). Fractional oxygen extraction increased significantly but not with a change as high as in hypoxic hypoxia 0.31 (range, 0.20-0.41) vs. 0.49 (range, 0.41-0.54). CONCLUSIONS: In comparison with hypoxic hypoxia, critical values of SvO2 are higher in anemic hypoxia, indicating that oxygen unloading from blood to tissues is impaired in anemic hypoxia. These characteristics in oxygen transport and capillary hemodynamics should be taken into consideration when SvO2 is used in clinical critical care.

Use of teicoplanin in preterm neonates with staphylococcal late-onset neonatal sepsis.

OBJECTIVE: To study the clinical pharmacology of teicoplanin in babies admitted to a newborn intensive care unit, by monitoring serum levels, efficacy and potential side effects. METHODS: An open, nonrandomized descriptive study was performed in the neonatal intensive and high care unit of the University Hospital Maastricht, The Netherlands. Twenty-three preterm neonates, gestational age ranging from 26 to 32 weeks (median 28.4 weeks), postnatal age from 5 to 47 days, and birth weight from 570 to 1,740 g, presenting with (suspected) late onset septicemia, were studied. Of 21 culture-proven septicemias, 20 were caused by staphylococci. The teicoplanin loading dose was 15 mg/kg i.v., followed by a maintenance dose of 8 mg/kg every 24 h. Intravenous gentamicin was also administered pending blood culture. Serum teicoplanin concentrations were measured by fluorescence polarization immunoassay. Clinical and microbiological cure/failure rates were determined and possible side effects were monitored. RESULTS: The study of individual pharmacokinetics during multiple-dose intravenous infusions was rendered impossible by apparently inaccurate dosing. Peak (30 min after end of the infusion) and trough teicoplanin levels were stable throughout the study and averaged 27.8 (interquartile range 23.7-32.9) and 12.3 (interquartile range 9.1-16.8) mg/l, respectively. The microbiological and clinical cure rates were 90% in gram-positive septicemia. There was no apparent toxicity. CONCLUSIONS: Inaccurate drug administration was a problem in this study, making a multidose pharmacokinetic study impossible. It is possible that inaccurate drug administration and not current dosage guidelines yielded trough levels below 10 mg/l in 57 (32%) of 176 instances. This pharmaceutical aspect clearly warrants further study. However, microbiological and clinical cure rates were high in gram-positive septicemias. No side effects attributable to teicoplanin therapy were encountered.

Click-evoked oto-acoustic emission measurement in preterm infants.

UNLABELLED: Click-evoked oto-acoustic emissions (CEOAE) are acoustic responses produced by the inner ear, reflecting functional auditory integrity. We studied both the success rate of the CEOAE method and the CEOAE presence in preterm infants during their stay at the Neonatal Intensive Care Unit (NICU), by analysis of the results of longitudinal CEOAE measurements in 19 preterm infants. The CEOAE method proved to be feasible in the majority of the population under study; the CEOAE measurement failed in 8% of the total of 226 attempts. Within the range of 30-40 weeks post-conceptional age (PCA) the CEOAE presence increased from about 50% to 80%. These results show the possible clinical application of CEOAE in a NICU for the monitoring of cochlear function during treatment of preterm infants. CONCLUSION: Bedside CEOAE measurement in preterm infants in a NICU is feasible at a PCA as low as 30 weeks.

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.

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.

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.

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.

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.

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.

Effect of sustained inflations applied directly after cord clamping on lung function in premature newborn lambs.

We studied the possibility of improving lung volume and therefore clinical outcome in premature newborn lambs by increasing the inspiratory volumes during the first minute after birth. Sixteen lambs from eight were delivered by hysterotomy after 130-131 days' gestation. In eight lambs the lungs were inflated with a bag with a sustained inspiratory inflation (SI) of 5 s and expiratory time of 5 s during the first four inflations after cord clamping and then mechanically ventilated. Their siblings did not receive SI and served as a control group. At 8 h postnatally, the SI and control groups showed the following results (mean +/- SEM): mean airway pressure 14.8 +/- 1.8 cmH2O versus 11.9 +/- 1.1 cmH2O, PaO2 41.5 +/- 7.3 kPa versus 31.3 +/- 7.7 kPa, alveolar-arterial oxygen gradient 359 +/- 55 mmHg versus 437 +/- 58 mmHg. Clinical course, incidence of pneumothorax, oxygenation index, total static compliance, parenchymal-alveolar air area ratio or mortality rate were not different. There was no significant difference between the two groups at this time or at any other time during the experiments.

Cardiovascular changes during sustained lung inflations in premature newborn lambs.

We studied the effect of sustained inspiratory inflations (SI) on the cardiovascular system by measuring mean central venous pressure (MCVP), mean arterial blood pressure (MABP) and heart rate (HR), before and during sustained lung inflations in premature lambs (128-133 days' gestation). SI consisted of four inflations of 5 s at a peak inspiratory pressure of 35 cmH2O, with a mixture of 5% carbon dioxide and 95% oxygen. Each inflation was followed by a positive end-expiratory pressure of 5 cmH2O for 5 s. Percentage change from baseline was -3.88% for MABP and -2.55% for HR during the first inflation. The changes in MCVP fluctuated with each inflation (mean 9.61%; p < 0.01 versus baseline) and deflation (mean -3.87%; p < 0.05 versus baseline). These changes were dependent on the time after birth and the pressure used for SI. The observed cardiovascular changes produced by this procedure are considered clinically relevant when managing premature infants with a high risk of intraventricular haemorrhage.

Effect of maternal hypoxemia on behavior in unanesthetized normoxic or mildly hyperoxic fetal lambs.

To determine whether hypoxemia inhibits fetal activity by substances from the mother or placenta, six fetal lambs were chronically instrumented at 128-132 days gestation for extra-corporeal membrane oxygenation (ECMO). Severe maternal hypoxemia (arterial PO2 decreased to 6.00 +/- 0.60 kPa) was produced while fetal arterial PO2 was maintained normoxic or mildly hyperoxic using ECMO. The incidences of fetal breathing movements were 34.8 +/- 3.1% (SE) during baseline before ECMO, 36.8 +/- 3.4% during baseline with ECMO, and 21.4 +/- 3.5% (P < 0.05 compared with baseline with ECMO) during maternal hypoxemia. The durations of periods of breathing were 9.8 +/- 1.2 min before ECMO, 9.3 +/- 1.1 min with ECMO, and 10.5 +/- 1.7 min (P = NS) during maternal hypoxemia. In 7 of 14 maternal hypoxemia experiments, breathing activity stopped too late (7-23 min) to be attributed to maternal hypoxemia. Fetal electrocorticographic activity (P = NS), nuchal electromyographic activity (P = NS), and eye movements were normal before ECMO, with ECMO, and during maternal hypoxemia. Fetal blood pressure and heart rate did not change. We conclude that the inhibition of fetal activity during maternal hypoxemia does not seem to be mediated by release of factors from the maternal side of the placenta or the ewe.

Effect of mild hypocapnia on fetal breathing and behavior in unanesthetized normoxic fetal lambs.

We hypothesized that the level of arterial PCO2 (PaCO2) affects the incidence of fetal breathing movements and electrocorticographic (ECoG) states in chronically instrumented fetal sheep. Six fetuses of 128-132 days gestational age were instrumented for recording fetal behavior and for later connection to an extracorporeal membrane oxygenation (ECMO) system to change fetal blood gases. Before ECMO fetal arterial pH and blood gases were pH 7.40 +/- 0.01, PaCO2 42.9 +/- 1.5 Torr, and arterial PO2 (PaCO2) 19.2 +/- 1.7 Torr; during ECMO in normocapnia they were pH 7.37 +/- 0.01, PaCO2 46.1 +/- 0.7 Torr, and PaCO2 27.6 +/- 3.0 Torr; and during ECMO in mild hypocapnia they were pH 7.47 +/- 0.01, PaCO2 35.3 +/- 1.7 Torr, and PaCO2 26.6 +/- 1.7 Torr. The overall incidence of breathing movements, the incidence of breathing movements during low-voltage (LV) ECoG activity, and the mean duration of periods of breathing decreased significantly during hypocapnia. Fetal ECoG activity showed normal cycling during the periods of mild hypocapnia, and the mean duration of LV ECoG periods did not change. During mild hypocapnia, eye movements remained associated with LV ECoG activity and nuchal electromyographic activity remained associated with high-voltage ECoG activity. These results suggest that the presence of breathing movements in fetal life is not only dependent on the behavioral state but also on the level of fetal PaCO2.

Effects of partial plasma exchange transfusion on blood flow velocity in large arteries of arm and leg, and in cerebral arteries in polycythaemic newborn infants.

Continuous wave Doppler velocimetry was performed in brachial, femoral and cerebral arteries in four preterm, four small-for-gestational-age (SGA) and eight appropriate-for-gestational age (AGA) polycythaemic newborns before and at 3 and 24 h after partial plasma exchange transfusion and in 18 matched controls at 3 and 24 h after birth. In peripheral arteries, end-diastolic flow velocity was zero in all eight AGA controls, but only in two of the other infants. Consequently, mean flow velocity and red cell transport in AGA controls were significantly lower than in the other five groups, which did not differ. Partial plasma exchange transfusion did not influence flow velocities and red cell transport in peripheral arteries, but normalized the flow velocities in cerebral arteries in all three subgroups of polycythaemic infants, which were lower than in control infants. Cerebral red cell transport in controls increased significantly between 3 and 24 h, and in polycythaemic infants between 0 and 3 h after partial plasma exchange transfusion. In conclusion, reduction in haematocrit had different effects on blood flow velocity and red cell transport of peripheral and cerebral vessels, suggesting that the increased cerebral blood flow velocity after partial plasma exchange transfusion is not simply due to a reduction in viscosity or oxygen content of the blood. The lower peripheral blood flow velocities in normocythaemic AGA infants as compared to all other groups, suggest that the level of maturity is an important determinant for the capacity to regulate blood flow.

The effect of hypocapnia and mechanical pulmonary stress on lung tissue in newborn lambs.

Positive pressure ventilation, using high inspiratory pressures, often causes lung damage. When associated with hypocapnia, it can produce severe focal alveolar alkalosis and can cause damage in areas of low blood flow. A vein-to-vein extracorporeal membrane oxygenator (ECMO) system was used to control blood gases independently of mechanical ventilation in 12 healthy newborn lambs. After connection to the ECMO system, ventilation was started with a peak inspiratory pressure of 35 cm H2O and a positive end-expiratory pressure of 5 cm H2O; the ventilator rate was 40/min with I:E = 1.5 and FiO2 = 1.0. In 6 of the 12 lambs sweep gases through the silicone membrane were regulated to assure arterial normocapnia. The other 6 were ventilated with the same settings and perfused with the same pump flow, but PaCO2 was allowed to fall to hypocapnic levels. The lambs were ventilated for 4 h. Average pH and PaCO2 were 7.62 +/- 0.14 and 2.11 +/- 0.54 kPa, respectively, in the hypocapnic group and 7.39 +/- 0.11 and 4.79 +/- 0.51 kPa in the normocapnic group. After sacrificing the lambs, the lungs were inspected macroscopically and microscopically by computer-assisted morphometry to assess atelectasis and lung edema. Macroscopically there were no hemorrhages, barotrauma or widespread atelectasis of the lungs in either group. The thickness of interlobular lung septa in the right upper lobe was 32.5 +/- 18.0 microns for the hypocapnic group and 29.7 +/- 12.5 microns for the normocapnic group. The parenchymal-alveolar area ratio in the right upper lobe was 28.4 +/- 5.04 and 24.6 +/- 3.75% in the hypocapnic and normocapnic groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Post-asphyctic encephalopathy of the neonate following administration of nalbuphine during childbirth]. / Postasfyctische encefalopathie van de pasgeborene na toediening van nalbufine tijdens de baring.

After an intramuscular injection of nalbuphine during parturition a foetal bradycardia of 30-40 beats/minute developed, which normalised after an intravenous maternal injection of naloxone. Because the cardiotocography did not show variability after the event, a caesarean section was performed. Six months later the child still had a severe neurological disorder which was attributed to intrauterine asphyxia. Several authors published reports in which no relevant clinical problems were described after nalbuphine given during labour. Recently, however, four children have been described with bradycardia and respiratory depression after maternal intravenous and/or intramuscular injection of nalbuphine. Apparently, the use of nalbuphine during labour can cause foetal bradycardia, both after intravenous and after intramuscular administration. Great reserve is advised regarding use of nalbuphine for this indication. The antidote naloxone should be within reach.

Fetal breathing is not initiated after cord occlusion in the unanaesthetized fetal lamb in utero.

We investigated the role of cord occlusion in the initiation of breathing at birth using an extracorporeal membrane oxygenator system to control fetal blood gases independently of the placenta in 12 chronically instrumented fetal lambs. In group IA (n = 9; exp = 12) PaCO2 was kept constant (5.62 +/- 0.21 to 5.70 +/- 0.23 kPa) during cord occlusion. Group IB (n = 7; exp = 8) were cord occlusion experiments from group IA in which no fetal breathing movements had occurred; CO2 flow to the membrane was increased and fetal PaCO2 rose significantly (5.45 +/- 0.24 to 8.27 +/- 0.56 kPa). In group II (n = 7; exp = 12) PaCO2 was allowed to increase from 5.98 +/- 0.24 kPa to 8.09 +/- 0.48 kPa after cord occlusion. Within 5 min of cord occlusion, FBM did not occur in 11 out of 12 experiments in group IA or in 11 out of 12 experiments in group II. In contrast in group IB breathing did occur in 5 out of 8 experiments. When they occurred, fetal breathing movements were always associated with low voltage electrocortical activity. Our results do not support the hypothesis that the initiation of breathing within 5 minutes of birth is dependent on an inhibitory factor of placental origin. Furthermore these data suggest an association between the presence of breathing and a substantial rise in PaCO2.

Circulating blood volume in appropriate and small for gestational age full term and preterm polycythaemic infants.

Relative circulating volume (CV) was determined in 31 polycythaemic newborn infants who underwent a partial plasma exchange transfusion (PPET). The infants were divided in four sub-groups: appropriate for gestational age (AGA) term and preterm infants, and small for gestational age (SGA) term and preterm infants. CV was calculated using a regression line between the number of exchange steps and central venous haematocrit values obtained before the procedure and after every exchange step. The median relative CV in all polycythaemic newborn infants was 94.0 (range 69-143) ml/kg. Irrespective of gestational age and birthweight the median relative CV in AGA infants was 86.5 (range 69-107) ml/kg, which differed significantly from the value of 106 (range 85-143) ml/kg found in SGA infants. If a PPET is indicated we recommend to calculate the exchange volume in AGA infants using a relative CV of 86 ml/kg and in SGA infants using a relative CV of 106 ml/kg.

Effects of partial plasma exchange transfusion on cerebral blood flow velocity in polycythaemic preterm, term and small for date newborn infants.

Isovolemic haemodilution with plasma was performed in 36 newborn infants with polycythaemia 3h after birth. Continuous wave Doppler ultrasonography was used to study the short and longer term influence of partial plasma exchange transfusion on cerebral blood flow velocity in both the anterior cerebral and mid cerebral arterial system up to 24h after haemodilution. The study group consisted of 11 preterm infants, 12 term infants, and 13 small for date infants. After exchange transfusion peripheral venous haemotocrit decreased from 72.5% to 59.4%. In all experimental groups cerebral blood flow velocity (CBFV) before exchange transfusion was significantly lower (18%-44%) than matched controls, and increased to control levels after exchange transfusion. CBFV improved most in preterm infants. After the transfusion the values were no different from the age-, weight-, sex- and parity-matched control groups, and they remained at this level during the next 24 h. No differences could be found between the anterior and mid-cerebral arterial system. When clinical symptoms were present, they subsided in all infants. In conclusion, partial plasma exchange transfusion has a favourable effect for at least 24 h on cerebral blood flow velocity in newborn infants with polycythaemia.