Effect of Continuous and Intermittent Exercises on Oxidised HDL and LDL Lipids in Runners.

We studied the effects of different types of exercises on the concentrations of oxidised HDL (oxHDLlipids) and LDL lipids (oxLDLlipids), serum lipids, antioxidant potential, paraoxonase and malondialdehyde in endurance runners by performing both a 40-min continuous run (velocity corresponding to 80% VO2max) and a 40-min intermittent run (2-min run, velocity corresponding to 100% VO2max, and 2-min rest) using a treadmill. Blood samples were taken before exercise, after 20 and 40 min of exercise, and 15 and 90 min after the end of exercise. The concentrations of oxLDLlipids remained unchanged during the running tests, but after a 90-min recovery the concentrations decreased by 4% (P<0.05) for the intermittent run and by 16% (P<0.01) for the continuous run. The acute effect of the intermittent and continuous run increased the concentrations of oxHDLlipids by 26 and 25%, respectively (P<0.001 for both). Interestingly, oxHDLlipids did not increase after the first half of the run in middle-distance runners during the intermittent run, and a similar phenomenon was seen in marathon runners during the continuous run. These results may indicate that acute physical exercise increases the transport of lipid oxidation products by HDL, although a different training history or genetic background may alter these acute responses.

Decreased training volume and increased carbohydrate intake increases oxidized LDL levels.

We studied effects of probiotics and training volume on oxidized LDL lipids (ox-LDL), serum antioxidant potential (s-TRAP) and serum antioxidants (s-α-tocopherol, s-γ-tocopherol, s-retinol, s-ß-carotene and s-ubiquinone-10) in marathon runners during 3-months training period, 6-days preparation period and marathon run. Runners (n=127) were recruited for a randomized, double-blind intervention during which they received either Lactobacillus rhamnosus GG (LGG, probiotic group) or placebo drink (placebo group) during whole study. During the preparation period, subjects decreased training and increased carbohydrate intake. Blood samples were taken at baseline, before 6-days preparation, before and immediately after the marathon. Probiotics did not have any effect on ox-LDL, s-TRAP or serum antioxidants levels during the study. Interestingly, ox-LDL increased by 28% and 33% during the preparation period and decreased by 16% and 19% during the marathon run in the placebo and probiotic groups, respectively (in all, P<0.001). No changes were seen in s-TRAP before marathon, but during run s-TRAP raised by 16% in both groups (both, P<0.001). The increase of ox-LDL level during the preparative period after several months' training suggests that aerobic training may reduce the concentration of ox-LDL and that decrease of training together with increased energy intake, mainly carbohydrate, before marathon is capable of increasing the level of ox-LDL.

Metabolic syndrome and short-term heart rate variability in young adults. The cardiovascular risk in young Finns study.

AIMS: Heart rate variability (HRV) can be used to estimate autonomic nervous control of the cardiovascular system. In middle-aged subjects, the metabolic syndrome (MetS) is associated with lower HRV. We hypothesized that alterations in autonomic balance are already present in young adults with the MetS, and analysed the association of short-term HRV with the MetS (using the National Cholesterol Education Program definition), in 1889 subjects aged 24-39 years. METHODS: Short-term (3 min) HRV analysis included high-frequency (HF), low-frequency (LF) and total (TP) spectral components of HRV and LF/HF ratio. RESULTS: The presence of the MetS was associated with lower HF, LF and TP in men and women, and with higher LF/HF ratio in women. In men, waist circumference was the strongest individual MetS component that associated with HRV. After adjustments for age and heart rate, MetS was associated with lower HF and higher LF/HF ratio in women, but only with a lower TP in men (all P < 0.05). CONCLUSIONS: MetS is associated with lower HRV in young adults. The individual components of MetS are differentially associated with HRV in men and in women. Our results are consistent with lower vagal activity and a possible increase in sympathetic predominance in women with the MetS. This sex difference in vagal activity and sympathovagal balance may partly explain the greater increase in cardiovascular risk associated with MetS in women than in men.

Chemical and physical properties of cyclone fly ash from the grate-fired boiler incinerating forest residues at a small municipal district heating plant (6MW).

In Finland, the new limit values for maximal allowable heavy metal concentrations for materials used as an earth construction agent came into force in July 2006. These limit values are applied if ash is utilized, e.g. in roads, cycling paths, pavements, car parks, sport fields, etc. In this study we have determined the most important chemical and physical properties of the cyclone fly ash originating from the grate-fired boiler incinerating forest residues (i.e. wood chips, sawdust and bark) at a small municipal district heating plant (6 MW), Northern Finland. This study clearly shows that elements are enriched in cyclone fly ash, since the total element concentrations in the cyclone fly ash were within 0.2-10 times higher than those in the bottom ash. The total concentrations of Cd (25 mg kg(-1); d.w.), Zn (3630 mg kg(-1); d.w.), Ba (4260 mg kg(-1); d.w.) and Hg (1.7 mg kg(-1); d.w.) exceeded the limit values, and therefore the cyclone fly ash cannot be used as an earth construction agent. According to the leached amounts of Cr (38 mg kg(-1); d.w.), Zn (51 mg kg(-1); d.w.) and sulphate (50,000 mg kg(-1); d.w.), the cyclone fly ash is classified as a hazardous waste, and it has to be deposited in a hazardous waste landfill.

Clinical testing of thermally stimulated cardiovascular oscillations in man.

STUDY OBJECTIVE: The study assessed the physiological validity of an automatic thermal stimulation method to induce synchronised oscillations in the neural cardiovascular control system. DESIGN: Automatic alternating rhythmic warm and cool immersion of different skin areas of 18 males was done at different frequencies and water temperatures. The neurally mediated responses to the periodic thermal stimulation were measured from skin blood flow and heart rate and compared to those of a sham stimulation. Respiration was monitored for control purposes. The reproducibility of the stimulation and responses was examined. SUBJECTS: 18 young males volunteered for the study. MEASUREMENTS AND MAIN RESULTS: The water bath method produced reproducible thermal stimulation and responses of skin blood flow and heart rate. Rhythmic thermal stimulation at 0.013-0.096 Hz synchronised the oscillations of the forearm skin blood flow when the thermal stimulus amplitude exceeded 10 degrees C. The increase in the stimulus amplitude or enlargement of the stimulus area did not further increase the oscillatory response of skin blood flow. Sham stimulation or mean temperature of the periodic thermal stimulation in the range 23-33 degrees C did not influence the oscillations of skin blood flow. Local cooling of the stimulated lower legs attenuated the response of skin blood flow. Both thermal stimulation and sham stimulation affected heart rate, but no stable synchronisation of the periodic heart rate variability was found at supine rest. Thermal stimulation of the sitting subjects' forearm instead of legs increased the synchronisation of the periodic heart rate variability. CONCLUSIONS: The response of skin blood flow agreed with the theory of the thermal entrainment. In a supine man, both thermal stimulation and non-specific central nervous influences induced significant and reproducible interactions with periodic heart rate variability and respiration.

A non-invasive method for testing neural circulatory control in man.

Exaggerated cardiovascular responsiveness is common in young men and may cause non-specific symptoms and poor performance. Conventional autonomic function tests are not clinically useful. We have therefore designed a thermal entrainment method to evaluate sympathetic and parasympathetic cardiovascular function in subjects with dystonic symptoms and orthostatic intolerance. Oscillations of thermal gradient in the skin were produced by standardised periodic stimulation of the lower part of the arm with warm and cool water. Vasomotor activity of the skin induced oscillations of arterial blood pressure which were thought to be regulated by sympathetic and parasympathetic heart rate control and by oscillation of the sympathetically controlled peripheral vascular resistance. We tested the method in subjects with cardiovascular symptoms (n = 7) and controls (n = 7). At supine rest, the frequency response of the heart rate variability to the thermal stimulation at frequencies of 0.01, 0.02, 0.03 and 0.1 Hz was significantly different (p = 0.008) between symptomatic subjects and controls. The gain of the heart rate control was increased to 0.03 Hz [-1.3(SEM 0.5) dB v -3.8(0.8) dB, p = 0.068] and decreased at 0.1 Hz [-3.9(1.1) dB v -1.5(0.6) dB, p = 0.076] in the test group compared to the control group. At stimulus frequencies of less than 0.03 Hz the individual overall heart rate variability of the subjects with symptoms stayed below the mean control value, at 60(6) ms v 79(15) ms, p = 0.16. The cutaneous temperature oscillations at the site of stimulation, frequency response of the oscillations of the skin blood flow and respiration to the thermal stimulation, and mean heart rate were similar in the both groups. The results show that this thermal entrainment method quantifies the increased sympathetic and decreased parasympathetic cardiac control of subjects with dystonic symptoms.

Decreased heart rate variation in decerebration syndrome: quantitative clinical criterion of brain death?

Heart rate variation (HRV) was measured in 12 children with brain death. Computer analysis demonstrated an overall heart rate variation (RMSM) of 3.5 to 9.6 msec (mean, 6.0 msec). The respective figures for beat-to-beat variation (RMSSD) were 4 to 16 msec (mean, 7.7 msec). Normal infants (RMSM, 20 to 30 msec) and children (RMSM, 50 to 90 msec) and infants with respiratory distress syndrome (RMSM, 10 to 20 msec) have a clearly higher HRV than those with brain death. In all subjects a periodic component of the HRV with a cycle length of 5.9 +/- 0.26 seconds was discovered. In five patients an additional periodic component was found that corresponded exactly to the rate of artificial respiration. This study demonstrated the value of accurate digital techniques in the characterization of fixed heart rate in decerebration. This phenomenon could be considered one clinical criterion of brain death.

Children in sauna: cardiovascular adjustment.

Children's circulatory adjustment to a 10-minute heat stress in a climatic chamber was studied in 61 children and 20 adolescents and young adults. The thermal conditions corresponded to those of an ordinary Finnish sauna bath. In all subjects the rectal temperature and heart rate increased during the heat exposure (P less than .001). Systolic and diastolic blood pressures remained unchanged in sauna, but the systolic and especially the diastolic blood pressure decreased (P less than .001) in children less than 10 years of age immediately after the heat exposure; two vasovagal collapses developed. Cardiac output increased in all but the less than 5-year-old children (P less than .001). This was due to a significant decrease in stroke volume (32.9%) (P less than .001) in children less than 5 years old. Stroke volume declined slightly even in the older subjects. These changes indicate that the Finnish sauna bath puts great demands on a child's circulatory regulation. To avoid possible cardiovascular side effects, particularly small children should be supervised carefully during sauna bathing.

Colloid osmotic pressure of umbilical cord plasma in healthy and sick newborn infants.

Colloid osmotic pressure of umbilical cord plasma was measured in 242 healthy infants, in 34 infants with respiratory distress syndrome (RDS), in 18 infants with asphyxia, in 13 infants who were small for gestational age, in 15 infants born to mothers with diabetes mellitus, and in 18 infants born to mothers with pregnancy-induced hypertension. In healthy infants, colloid osmotic pressure correlated highly significantly with umbilical cord blood total protein level, gestational age, and birth weight. In infants with RDS, no correlation between colloid osmotic pressure and gestational age or birth weight was found. Infants with RDS and gestational age between 36 and 38 weeks had significantly lower colloid osmotic pressure than healthy infants, whereas colloid osmotic pressure of infants with RDS and gestational age between 32 and 35 weeks did not differ from that of healthy infants of corresponding gestational age. Healthy term infants delivered by cesarean section had significantly lower colloid osmotic pressure than infants delivered vaginally. Infants with asphyxia had significantly higher colloid osmotic pressure than healthy infants. Colloid osmotic pressure is related to the lung maturity of the near-term and term neonate. Infants with a colloid osmotic pressure greater than 16 mm Hg are unlikely to develop RDS.

Apolipoprotein E polymorphism and serum lipids in a randomized, prospective trial of an infant diet with reduced saturated fat and cholesterol.

BACKGROUND: The inherited apolipoprotein E (apoE) phenotype may determine effectiveness of dietary atherosclerosis prevention. This study analyzes the effects of apoE phenotypes on changes in serum lipid concentrations in a 6-month prospective, randomized trial of a low-saturated-fat, low-cholesterol diet in infancy. PATIENTS AND METHODS: One thousand sixty-two healthy infants were randomized to intervention and control groups at the age of 7 months. Counseling was provided to the intervention families when the children's ages were 7, 8, and 10 months. Dietary goals were the child's intake of energy ad libitum, fat at 30% to 35% of energy, cholesterol at less than 200 mg/d, and saturated, monounsaturated, and polyunsaturated fatty acids at a 1:1:1 ratio. Control families consumed an unrestricted diet. The apoE phenotype of 846 of the infants was determined; serum lipid and lipoprotein concentrations were measured at 7 and 13 months of age; and nutrient intakes were analyzed using 3-day food records at 8 and 13 months of age. RESULTS: At 7 months of age, serum cholesterol concentration was higher in apoE4-positive infants (E2/E4, E3/E4, and homozygous E4) than in apoE4-negative infants (159 +/- 31 mg/dL [4.10 +/- 0.81 mmol/L] vs 150 +/- 29 mg/dL [3.89 +/- 0.74 mmol/L]). The high-density lipoprotein cholesterol concentration was slightly lower in apoE4-positive infants than in apoE4-negative infants (34 +/- 8 mg/dL [0.88 +/- 0.20 mmol/L] vs 35 +/- 7 mg/dL [0.91 +/- 0.19 mmol/L]). Between 7 and 13 months of age, the serum cholesterol concentration in infants in the intervention group was unchanged, apoB concentration increased slightly, and apoA1 concentration decreased. In the control infants, serum cholesterol concentration increased 9 +/- 25 mg/dL (0.24 +/- 0.65 mmol/L), apoB concentration increased markedly, and apoA1 concentration was stable. Changes in serum lipid and apo concentrations that resulted from the dietary intervention were independent of the apoE phenotype. CONCLUSIONS: The apoE phenotype influenced serum cholesterol concentration markedly by 7 months of age. Between the ages of 7 and 13 months, a reduced saturated fat and cholesterol diet effectively prevented the age-associated increases in serum cholesterol and non-high-density cholesterol concentrations that were obvious in the control infants. The effects of the diet occurred in the infants independently of the apoE phenotype.

Heart-rate variability and SIDS. Examination of heart-rate patterns using an expert system generator.

In a prospective, population-based study, HRV was analyzed from 24-hr tape recordings made on 16 full-term and one preterm infant who had subsequently suffered SIDS and compared to similar data on 23 control infants (n of recordings, 44). In the SIDS group, heart rate was higher, and overall and beat-to-beat HRV (CV, CVS, respectively) were lower, than in the controls, but not significantly. Respiratory rate and respiratory HRV (by spectral analysis) were similar in both groups. Assuming that cardiorespiratory mechanisms of SIDS are multifactorial, we expected that several subgroups would be detected in both test groups. Therefore, the average data for each recording were subsequently examined by means of an expert system generator (ExTran, Intelligent Terminals Ltd., Edinburgh, UK). By rules induced with 25 nodes, the following results were obtained: 16/44 recordings were diagnosed as SIDS on the basis of (1) respiratory rate (RR) less than 33 and CV less than 3.46% (n = 8); (2) RR greater than 33, CVS less than 2.18%, and BW greater than 3,520 g (n = 4); and (3) RR greater than 33, CVS less than 2.18%, BW less than 3,520 g, HR greater than 136, and CV greater than 1.89% (n = 4). Seventeen of 44 were considered as non-SIDS when (1) RR was 33-47.4, CVS greater than 2.18%, and RSA less than 74.3 and (2) RR greater than 33, CVS less than 2.18%, BW less than 3,520 g, and HR less than 142. The remaining 11 cases required more complicated rules in order to be classified. This study shows that although the trend of increased HR and decreased HRV in the SIDS cases was statistically non-significant, an expert system program may be helpful in defining decision rules to identify cases of SIDS on the basis of cardiorespiratory data.

Nutrient intakes by young children in a prospective randomized trial of a low-saturated fat, low-cholesterol diet. The STRIP Baby Project. Special Turku Coronary Risk Factor Intervention Project for Babies.

OBJECTIVE: To evaluate the impact of individualized and repeatedly given dietary counseling on fat intake and nutrient intake of children aged 8 months to 4 years. DESIGN: Prospective randomized clinical trial. PARTICIPANTS: Children (N = 1062) from 1054 families were randomized to an intervention (n = 540) or a control (n = 522) group when each child participant was 6 months old. INTERVENTIONS: The children in the intervention group were counseled to reduce their intake of saturated fat and cholesterol but to ensure their adequate energy intake. Dietary issues were discussed with the families of the children in the control group only briefly according to the current practice of well-baby clinics. MAIN OUTCOME MEASURES: Food consumption was evaluated by using 3- and 4-day food records that were kept at 5- to 12-month intervals, and nutrient intakes were analyzed with a Micro Nutrica computer program (Social Insurance Institution, Turku, Finland). RESULTS: The intake of fat (29% of the energy intake) and cholesterol (70 mg) showed no differences between the groups of children at 8 months of age. The fat intake in the children in the intervention group was then continuously 2% of the energy intake below that of the children in the control group (P < .001). After the age of 13 months, the cholesterol intake of the children in the control group exceeded that of the children in the intervention group by 20 mg (P < .001). The children in the intervention group consumed 3% (of the energy intake) less saturated (P < .001) and 1% (of the energy intake) more polyunsaturated fats (P < .001) than did the children in the control group at age 13 months and older. The carbohydrate intake was slightly higher in the children in the intervention group than in the children in the control group. Intakes of vitamins, minerals, and trace elements showed no differences between the 2 groups. CONCLUSIONS: The intakes of fat by the children in the intervention and control groups were markedly below values that were recommended for the first 2 years of life. Despite the low intake of fat, the intake of other nutrients fulfilled current recommendations, except for vitamin D and iron. Individualized dietary counseling that led to clear changes in the type of fat intake had a minimal effect on vitamin or mineral intakes.

Associations between physical activity and risk factors for coronary heart disease: the Cardiovascular Risk in Young Finns Study.

Risk factors such as high serum cholesterol concentration measured in young adulthood predict premature coronary heart disease (CHD) in the middle-aged. The objective of this study was to analyze the associations between physical activity and CHD risk factors--body composition, blood pressure, serum lipids, apolipoproteins, and insulin--in children and young adults. The design was a cross-sectional study of atherosclerosis precursors in children and young adults using a cohort of children and young adults (N = 2,358) aged 9 to 24 years to determine indices of physical activity, measurements of anthropometric characteristics, blood pressure, serum lipids, apolipoproteins A-I and B, and insulin. The results show that a high level of physical activity was associated with high serum high density lipoprotein cholesterol (HDL-C) and HDL2-C concentrations, and low levels of serum triglycerides (TG), apolipoprotein B and insulin in males. However, in females, the influence of physical activity was evident only on TG level. In both genders, physical activity was inversely associated with obesity. In all these associations, a significant dose-related relationship was observed. We found no association between physical activity and blood pressure. In conclusion, physical activity is associated with a favorable serum lipid profile already during childhood and early adulthood in a dose-related manner, particularly in males. The promotion of physical activity is important in childhood in preventing obesity and premature cardiovascular disease.

Transcephalic electrical impedance provides a means for quantifying pulsatile cerebral blood volume changes following head-up tilt.

Transcephalic electrical impedance (delta Z) was used to assess pulsatile cerebral blood volume changes while tilting nine premature (30-34 weeks) infants 20 degrees head up. High-frequency (1.50-4.00 Hz) delta Z variability decreased 27% while heart rate did not show any change. We would like to suggest that the variability of transcephalic electrical impedance analysed with spectral estimation seems to provide a means for quantifying alterations in cerebral circulation.

Skin blood flow oscillations respond more effectively to rhythmic thermal stimulation than to continuous or periodic breathing in newborn infants.

Effect of continuous (n = 30) and periodic (n = 5) breathing on forehead skin blood flow (SBF) oscillations was studied in healthy 3-day-old preterm and term infants. Femoral SBF was measured in 10 of the term infants during continuous breathing. Respiratory and SBF signals were analysed by power spectrum during the control period. The signal analysis was repeated during rhythmic thermal stimulation which was applied to the skin of each infant in order to synchronise spontaneous SBF oscillations. During the control period, the forehead and femoral SBF of all the studied infants oscillated at frequencies corresponding to the frequency of regular continuous breathing. External thermal stimulation decreased these high-frequency oscillations of forehead SBF in both preterm and term infants. Oscillations in femoral SBF of term infants remained unchanged. During periodic breathing, the spontaneous forehead SBF oscillation was synchronised to the frequency of respiratory amplitude variation. Despite periodic breathing, thermal stimulation was able to resynchronise the SBF oscillation to the stimulation frequency in 4/5 infants. Forehead SBF oscillates at the frequency of both continuous and periodic breathing in preterm as well as in term infants on postnatal day 3. Rhythmic thermal stimulation synchronises SBF and affects SBF more effectively than continuous or periodic breathing. These results suggest functional neural control of cutaneous vasculature at birth.

Impact of thermal vasomotor control on the heart rate variability of newborn infants.

The reactivity of the periodic heart rate variability (HRV) to the thermal vasomotor control was studied during quiet sleep in a total of 20 neonates which were classified in 5 groups according to their maturity. Thermal stimulation on the peripheral skin was applied by an air blower at the rates of 5, 2.5 and 1.5 cycles/min. The oscillation of successive R-R intervals of the ECG was determined by a hybrid computer technique during thermal stimulations and compared to spontaneous HRV activity. The indices of the HRV and the total power of the periodic HRV remained unchanged during thermal stimulations. The response of the periodic HRV was selective at the spectral band corresponding to the frequency of stimulation. It was maximal at 5 cycles/min. The relative response was highly significant (P less than 0.001) and it increased with increasing maturity. The state of SGA (small for gestational age) seemed to decrease the vasomotor response of the HRV. The results suggested that the thermal vasomotor control was functional already in small preterm infants and it tended to increase with increasing maturity as does the autonomic cardiac control in general.

Post-prandial effects in reactivity of forehead and mid-femoral skin blood flow and heart rate in neonates.

The effect of post-prandial period on the cutaneous vascular reactivity was studied in twelve full-term infants on their 3rd postnatal day. The differences in vasomotor reactions between the forehead and femoral skin were also investigated. Two 10-min control registrations about 30 and 90 min after feeding were followed by a registration of equal duration during thermal stimulation of the skin. The lower extremity of each infant was stimulated by warm and cool air currents (5 cycles/min) to induce periodic vasomotor changes. The fast Fourier transform was used to compute variability spectra for the recorded skin blood flow, heart rate and respiratory wave form signals. The skin blood flow became synchronised to the thermal stimulation in both skin regions. Neither the spontaneous nor synchronised oscillations of the skin blood flow differed significantly between femoral skin and forehead. The post-prandial time did not have any influence on this synchronisation. Heart rate variability was synchronised to the periodicity of thermal stimulation more 1.5 h after feeding than 0.5 h after feeding. Respiration was not affected. The results show that increasing post-prandial time has no influence on the synchronised oscillations of skin blood flow. However, it potentiates reactivity of heart rate to perturbations in the peripheral vasculature.

Dynamics of vasomotor thermoregulation of the skin in term and preterm neonates.

Eighteen fullterm infants and 17 preterm infants were studied on their 3rd day of life to investigate the reactivity of skin blood flow to thermal stimulation. The infants were studied during quiet sleep. After a 10-min control period a constant air current was used to synchronise the external cutaneous stimulus to the distal lower extremity of each infant: the heating element of an air blower was automatically switched on and off to generate successive warm and cool periods of equal duration (5 cycles/min). Heart rate (HR), skin blood flow (SBF) and respiratory waveform signals were recorded and their variability was analysed using the fast Fourier transform and spectral analysis. Fullterm infants showed a clear response to external thermal stimulation: both HR and SBF were synchronised to the stimulation frequency. A response of preterm infants was present but it was markedly attenuated in comparison to term infants. The effect of stimulation did not seem to be dependent on postnatal age. The results suggest that the vasomotor control is immature in preterm infants.

Association of abnormal flow velocity waveforms in the uterine artery with frequency-specific fetal heart rate variability.

The aim of the study was to determine if abnormal flow velocity waveforms in the uterine artery are associated with altered frequency-specific fetal heart rate variability (HRV). Fetuses in the last third of gestation were studied. In seven fetuses the pulsatility index (PI) of the blood flow velocity waveform in the uterine artery was increased (Group II), and in ten fetuses the PI was normal (Group I). Frequency-specific HRV (0.025-0.07 Hz, 0.07-0.13 Hz, 0.13-1.0 Hz) was quantified by power spectral analysis and correlated with the PI in the uterine artery, umbilical artery and the middle cerebral artery. The slow variability dominated the fetal HRV. There was no difference between the groups in the mean frequency-specific variability. In Group II, an increase of the PI in the umbilical artery and a decrease in the middle cerebral artery correlated with an increase of HRV, the increase being greatest at the lowest frequency band.

Cerebral circulation assessed by transcephalic electrical impedance during the first day of life--a potential predictor of outcome?

Pulsatile changes in intracranial blood volume (transcephalic electrical impedance, delta Z), arterial blood pressure (aBP) and respiration were studied during the first day after birth in 42 neonates with a birth weight of 1040-3850 g and gestational age of 26-36 weeks. The neurological outcome was assessed at 1 year of age to study the predictive ability of delta Z. delta Z, ECG, respirogram and direct aBP were recorded at 8-h intervals. Outcome was adverse in seven infants of whom two died from severe peri-intraventricular haemorrhage. PCO2 was higher (6.2 kPa) in the infants with adverse outcome than in those infants with favourable outcome (5.0 kPa) (P = 0.004). Blood glucose (4.5 vs. 3.3 mmol/l, P = 0.030) and first day administration of fluid (80 vs. 63 ml/kg/day, P = 0.003) behaved, respectively. Of the infants receiving dopamine therapy, 60% had adverse outcome while only 11% of those not receiving dopamine had adverse outcome (P = 0.016). Of the infants with high diastolic blood pressure levels, 32% had adverse outcome, while none with low diastolic blood pressure levels had adverse outcome (P = 0.031). Spectral analysis was used to examine signal variabilities in the frequency domain. During the first 24 h of life, the variabilities of aBP and respiration were equal in all the infants. The high-frequency delta Z signal variability (1.50-4.00 Hz, heart rate level) was found to be lower in the infants with adverse outcome (330 units) than in the infants with favourable outcome (1280 units, P = 0.017). The low delta Z variability allowed us to assume that there is a decrease of pulsatile cerebral blood flow (CBF) in the infants with adverse outcome. We speculate that this may result from the 'no reflow phenomenon', increased tissue pressure due to ischaemia and/or PIVH, the 'brain sparing effect' or constriction of main cerebral arteries due to increased pressure support or metabolic factors (PCO2, glucose). We believe that transcephalic impedance provides a potential cot-side method for monitoring cerebral circulation in the neonatal period with an ability to predict outcome.