Serial Cardiopulmonary Exercise Testing in Patients with Previous Fontan Surgery

Patients with previous Fontan surgery have reduced peak oxygen consumption (Vo ₂), and data regarding progression of exercise intolerance is limited. The purpose of this study was to assess the evolution of exercise tolerance in patients with previous Fontan surgery. We performed a retrospective cohort study of patients with previous Fontan surgery who underwent cardiopulmonary exercise testing between November 2002 and January 2009. Patients were required to have completed at least two tests, with adequate levels of effort, ≥6 months apart. We identified 78 patients (55% male) who had undergone a total of 215 cardiopulmonary exercise tests. Age at initial study was 19.7 ± 10.2 years; time interval since previous Fontan surgery 13.3 ± 5.7 years; and time interval between the initial and the most recent exercise test was 3.0 ± 1.4 years. Morphologic left ventricle was present in 58 (74.4%) patients. At baseline, peak Vo ₂ averaged 24.7 ± 7.0 ml/kg/min (63.7% ± 15.8% predicted). At most recent study, peak Vo ₂ averaged 23.2 ± 7.2 ml/kg/min, (60.4% ± 13.9% predicted). Percent predicted peak Vo ₂ declined slowly, with a mean rate of decline of 1.25 ± 0.36 percentage points/y (p < 0.001). Most of the decline occurred in patients < 18 years of age (mean rate of decline 1.78 ± 0.46 percentage points/y; p = 0.0004). Thereafter, the rate of decline was less marked (mean rate of decline 0.54 ± 0.57 percentage points/y; p = not significant). Ventricular morphology, type of Fontan procedure, and cardiac medications were not predictive of progressive exercise intolerance. In conclusion, although the exercise function of previous Fontan patients tends to decline during late adolescence, it appears to stabilize during early adulthood.     

Cerebral Hemodynamics in the Presence of Decreased Systemic Venous Compliance in Patients with Fontan Physiology May Limit Anaerobic Exercise Capacity

Patients who have had the Fontan procedure report poor exercise performance. Fontan subjects can tolerate a higher level of sub maximal activity than might be anticipated from Vo ₂, suggesting a different mechanism of exercise limitation. Near-infrared spectroscopy (NIRS) provides a non-invasive, continuous method to monitor regional tissue oxygenation (rSO2) and thereby a window into regional oxygen supply–demand relationships. We hypothesized that Fontan patients would have altered rSO2 trends from normal population that might reflect the mechanisms of exercise limitation. All the patients without structural or acquired heart disease and Fontan patients were eligible for inclusion if they were ordered to undergo cardiopulmonary exercise testing (CPET). Four-site regional rSO2 were recorded continuously during exercise. The difference between the oxyhemoglobin saturation measured by pulse oximetry (Spo ₂) and NIRS (rSO2) was computed as the regional arterial–venous saturation difference (AVDO2). A total of 33 normal subjects and five Fontan subjects scheduled for CPET were recruited. None of the Fontan subjects had a fenestration of the conduit. In the cerebral circulation, the Fontan patients have a significantly higher initial slope of increasing AVDO2 compared with normals. After vAT, the AVDO2 slope is flat for Fontan patients (p = 0.02). There is also a substantially larger rebound of cerebral rSO2 than in normal subjects after QT (p < 0.0001). Reduced anaerobic exercise capacity in Fontan patients may be secondary to limitation of cerebral blood flow, secondary to low systemic venous compliance due to absence of a sub-pulmonary ventricle, and augmented hyperventilatory response during exercise.     

Desmopressin (DDAVP) responsiveness in children with von Willebrand disease

PURPOSE: To determine the pattern and predictors of response to desmopressin (DDAVP) in children with von Willebrand disease (VWD). METHODS: The authors reviewed the hospital records of all children with type 1 (n = 70) and type 2A (n = 5) VWD who were followed in the institution's Bleeding Disorders Clinic from January 1989 to June 2001 and who had a DDAVP challenge test after diagnosis. The major outcome evaluated was response to DDAVP, defined as an increase of greater than twofold over baseline of von Willebrand factor, ristocetin cofactor (VWF:RCo), and factor VIII coagulant (FVIII:C) and levels above 0.3 IU/mL. RESULTS: Response to DDAVP was observed in 56 (80%) of the 70 children with type 1 VWD. Age and baseline VWF:RCo and FVIII:C levels were positively associated with DDAVP response. A total of 36 children (28 responders, 8 nonresponders) with type 1 VWD were treated for bleeding episodes or for prophylaxis; of these 75% (6/8) of the nonresponders compared with 7% (2/28) of the responders to a DDAVP challenge test received blood component therapy (P < 0.01). One of the five children with type 2A VWD responded to DDAVP. CONCLUSIONS: DDAVP challenge tests are recommended in children with newly diagnosed VWD to identify responders in whom DDAVP may be used for the prevention or treatment of bleeding, thus avoiding exposure to blood products. The association of DDAVP response with age merits further investigation.     

Haemorheologic and fibrinolytic evaluation in obese children and adolescents

The haemorheologic condition was evaluated in 43 obese children and 35 controls. In 18 of the obese children and in 21 controls the euglobulin lysis time (ELT) was also studied. Blood viscosity at 94.5 and at 0.204 s^-1 shear rates, plasma viscosity, fibrinogen and erythrocyte filtration time were significantly higher in obese than in control children. No significant differences were observed in haematocrit levels. Triglycerides, non-esterified fatty acids (NEFA), pre--lipoprotein and insulin rates were all significantly higher in obese than in control children. There were no significant differences in glycaemia and in haemoglobin A1 values. ELT, both basal and after stimulation with 1-deamino-8-d-arginine-vasopressin (DDAVP), was significantly higher in the obese than in control children. The haemorheologic disturbances together with alterations of the haemostatic balance and fibrinolysis may be an important risk factor for the development of vascular changes at paediatric age.Abbreviations Htc haematocrit - BV blood viscosity - BV94 blood viscosity at 94.5 s^-1 shear rates - BV0.2 blood viscosity - PV plasma viscosity - RV relative viscosity - EFT erythrocyte filtration time test - ELT euglobulin lysis time - NEFA non-esterified fatty acids - HbA1 glycosilated haemoglobin - DDAVP 1-deamino-8-d-arginine-vasopressin - HDL high density lipoprotein - MCV mean corpuscular volume This study was supported by Consiglio Nazionale delle Ricerche, Grant no. 85.00477.56 and no. 86.01698.56     

Längsschnittuntersuchungen der physikalischen Kreislaufanalyse bei infektionskranken bzw. rekonvaleszenten Kindern

Zusammenfassung Bei insgesamt 364 Kindern im Alter von 4–14 Jahren wurden im Verlauf einer akuten Infektionskrankheit und in der Rekonvaleszenz Längsschnittuntersuchungen der physikalischen Kreislaufanalyse nach Wezler u. Böger durchgeführt. In den ersten Krankheitstagen ließ sich fast durchweg eine vasoconstrictorische Kreislaufdrosselung im Sinne einer Tendenz zur Zentralisation des Kreislaufs (Duesberg u. Schroeder) nachweisen. Dementsprechend waren die Werte von V_s, V_m, HJ, E/W, H_A, H_L, p vorzugsweise und die von PWG, E, W, p_s, p_d, p_m vorwiegend erhöht. Mit fortschreitender Genesung konnten wir ein Nachlassen dieser vasoconstrictorischen Grundeinstellung beobachten. Die Normalisierung der einzelnen Parameter der physikalischen Kreislaufanalyse setzte unterschiedlich ein. Richtzahlen werden gegeben.

---

Longitudinal section test of a physical circulatory analysis in infectious and convalescent children

Summary Longitudinal section tests were carried out during the acute stage of the infectious disease in a total of 364 children aged from 4 to 14 and during convalescence; these were based on a physical analysis of the circulation as suggested by Wezler and Böger. During the initial days of illness, a vasoconstrictive circulatory sparing effect with near central circulatory action was observed, as reported by Duesberg and Schroeder. The values of V_s, V_m, HJ, E/W, H_A, H_L, p were chiefly, and those of PWG, E, W, p_s, p_d, predominantly increased. The basic vasoconstriction remitted with progressive recovery and normalisation of the various parameters of the physical circulatory analysis occurred at different intervals. Figures are given as guidance.

     

Bronchopulmonary dysplasia and neurodevelopmental outcome in extremely preterm neonates

We tested the hypothesis that the use of supplemental oxygen (sO₂) at discharge from the NICU in extremely preterm neonates is associated with a greater risk of neurodevelopmental impairment (NDI) at 18 months corrected gestational age (CGA) than the risk of NDI of those neonates discharged in room air. Four hundred twenty-four charts were retrospectively reviewed from infants born at <27 weeks and transferred to Nationwide Children’s Hospital from December 1, 2004 to June 14, 2010. Use of sO₂ was evaluated on day of life (dol) 28, at 36 weeks post-menstrual age (PMA), and at discharge. Logistic regression was used to identify postnatal risk factors associated with sO₂ at discharge and NDI. At dol 28, 96 % of surviving patients received sO₂, and therefore had bronchopulmonary dysplasia (BPD) by definition from a National Institutes of Child Health and Human Development workshop. At 36 weeks PMA, 89 % continued on sO₂ (moderate/severe BPD), and at discharge, 74 % continued on sO₂. When factors associated with NDI were examined, the need for mechanical ventilation ≥28 days (adjOR?=?3.21, p?=?0.01), grade III–IV intraventricular hemorrhage (IVH) (adjOR?=?4.61, p?<?0.01), and discharge at >43 weeks PMA (adjOR?=?2.12, p?=?0.04) were the strongest predictors of NDI at 18 months CGA. There was no difference in Bayley Scales of Infant Development, third edition composite scores between patients with no/mild BPD and patients with moderate/severe BPD (cognitive p?=?0.60, communication p?=?0.53, motor p?=?0.19) or those scores between patients on and off oxygen at discharge (cognitive p?=?0.58, communication p?=?0.70, motor p?=?0.62). Conclusions: The need for sO₂ at discharge is not associated with an increased risk of NDI in these patients. The strongest predictors of poor neurodevelopmental outcome in this population were prolonged positive pressure support, grade III–IV IVH, and discharge at >43 weeks PMA.     

Management of severe chronic thrombocytopenia in von Willebrand's disease type 2B

Two patients with a long history of unexplained thrombocytopenia, eventually diagnosed with von Willebrand''s disease (vWD) type 2B are reported. In one patient with platelet counts of 80× 10⁹/l 1-desamino-8-D-arginine vasopressin (DDAVP) had a favourable effect during bleeding episodes. The second patient received intermediate purity von Willebrand''s factor (vWF)/factor VIII concentrate (Haemate HS), which helped haemostasis during tooth extraction. It increased platelet counts from 15 to 30 × 10⁹/l, whereas platelet transfusions produced no increase, nor prevented severe bleeding during abdominal surgery. Thus the treatment of vWD type 2B might depend on the degree of thrombocytopenia. It is recommended that in patients with mild to moderately decreased platelet counts, DDAVP treatment can be tried, whereas in patients with severely decreased platelet counts intermediate purity vWF/factor VIII concentrate substitution is preferred.
In addition, vWD type 2B should be considered in the differential diagnosis of any child with chronic thrombocytopenia as the treatment strategy is different.

     

Neurodevelopmental impairment at 2 years of age in children born before 29 weeks’ gestation with bronchopulmonary dysplasia

IntroductionVery preterm children are at a high risk for neurological impairment, especially those with bronchopulmonary dysplasia (BPD). The main goal of this study was to describe the neurodevelopmental impairment (NDI) at 2 years of corrected age in children born before 29 weeks’ gestation between 2010 and 2015 and affected by BPD at 28 days of life. We also searched for risk factors associated with NDI, especially postnatal steroid (PNS) administration.Material and methodsThis was a retrospective study comprising a cohort of children hospitalized at the university hospital in Grenoble, born before 29 weeks’ gestation between 2010 and 2015, and included in the monitoring network “Naitre et Devenir” (RND). Infants at 2 years of corrected age were classified as having NDI if they had at least one of the following outcomes: a global developmental quotient (DQ) on the revised Brunet–Lézine scale of < 85, blindness, deafness, or cerebral palsy (CP) graded as level 3 or more according to the Gross Motor Function Classification System.ResultsA total of 129 children were included, of whom 99 were monitored at the age of 2 years: 31.3% of the population had NDI and 4% had CP. The median DQ test result was 90 (interquartile 82–97). Factors associated with NDI in univariate analysis were low gestational age, low birth weight, a cord pH < 7.2, chorioamnionitis, treatment for persistent ductus arteriosus, longer oxygen therapy, and outborn status, which almost reached statistical significance. In multivariate analysis, low gestational age and outborn status remained statistically significant, while chorioamnionitis was found to have some association with NDI. While 13.1% of the followed-up population was treated with PNS, this risk factor was not associated with NDI.ConclusionIn a population of very preterm children, one third had NDI at 2 years of corrected age. Low gestational age, outborn status, and perinatal inflammation are associated with this unfavorable outcome. The frequency of sequelae confirms the importance of following up these children.     

Sedation for cardiac catheterization: A controlled study

Summary In a double-blind study we compared the effectiveness of a meperidine-promethazine-chlorpromazine combination (drug A) and a fentanyl citrate-droperidol combination (drug B) as sedatives for cardiac catheterization and angiography. The doses for drug A were meperidine, 1.84 mg/kg; promethazine, 0.46 mg/kg; and chlorpromazine, 0.46 mg/kg; for drug B they were fentanyl citrate, 1.25μg/kg; and droperidol, 62.5μg/kg. Drug A or B was assigned at random to each of 94 patients aged 3 to 34 years admitted for cardiac catheterization and was given intramuscularly 30 minutes before catheterization. Each patient who required additional sedation was given intravenously (IV) one fourth of the original dose of the same medication used for initial sedation. If still further sedation was required, diazepam, 1 to 2 mg IV, was administered. The effectiveness of sedation or need for additional medication in the group who received drug A were not significantly different from those in the group who received drug B: supplemental sedation was required in 8 of 47 (17%) with drug A and 8 of 47 (17%) with drug B. No significant differences between the two groups were noted for the mean values of heart rate, respiratory rate, oxygen consumption, cardiac index, left ventricular end-diastolic pressure, arterial oxygen saturation, pH,Po ₂, andPco ₂ measured during catheterization. No side effects were observed in either group, and all patients had a steady, uneventful recovery. We conclude that the meperidine-promethazine-chlorpromazine and the fentanyl-droperidol combinations were equally effective for precatheterization sedation with the dose used. Supported in part by grants HLB 5885 and HLB 10436 from the National Institutes of Health, Bethesda, Maryland     

Tidal volume and respiratory frequency in infants with bronchopulmonary dysplasia (BPD)

To examine the respiratory pattern in infants with BPD, we compared measurements in 4 infants not retaining CO₂ (P_ACO₂=40) with those in 4 infants retaining CO₂ (P_ACO₂=52). We also studied 14 healthy preterm infants, 7 not retaining CO₂ (P_ACO₂=32) and 7 retaining CO₂ (P_ACO₂=45). In infants with BPD, minute ventilation (V_E) was 0.996 (mean) and 1.002 1/min with and without CO₂ retention (P > 0.5). Tidal volume (V_T) was 12.6 and 21.1 (P < 0.001) and total duration of the respiratory cycle (T_tot) 0.77 and 1.33 (P < 0.005) with and without CO₂ retention. V_T/T_i were 45.00 and 44.89, respectively (P > 0.5). In preterm infants, V_E was 0.537 and 0.710 l/min with high and low CO₂ (P > 0.1). V_T was 15.4 and 11.00 (P > 0.2) and T_tot 1.63 and 0.99 (P < 0.002) with high and low CO₂. V_T/T_i was 32.08 and 30.56 (P > 0.5). These findings suggest: (1) in infants with BPD, V_T and frequency (f) change in much the same way as in adult subjects with chronic obstructive lung disease, i.e., V_T decreases and T_tot shortens (↑f) in association with high P_ACO₂; (2) mean inspiratory flow is essentially the same in infants with BPD who do and do not retain CO₂; and (3) in infants with normal lungs, V_T and T_tot increase (↓f) in association with high P_ACO₂, breathing pattern being entirely controlled via changes in the timing mechanism, the inspiratory drive remaining unaltered.     

Anaerobic threshold and the determination of training target heart rates in premenarchal girls

Summary The capability of children to respond to endurance training with increased aerobic capacity is unclear. Prepubertal subjects may require higher target heart rates than adults to increaseV o ₂ max, and previous studies failing to demonstrate aerobic trainability in children may have involved inadequate exercise intensity. In this study, heart rates at the anaerobic threshold, measured noninvasively as the ventilatory breakpoint (VBP), were determined during treadmill testing of 12 premenarchal girls to establish a metabolic-based target rate. The mean heart rate at VBP was 171 beats/min (±12 SD) with a range from 147 to 194 beats/min. Although a wide intersubject variability was observed, the rates at VBP exceeded those predicted by standard formulas for calculating target heart rates in adults by over 10 beats/min in a majority of the girls. These data indicated that target heart rate guidelines designed for training older individuals may not adequately stress oxygen delivery systems in prepubertal subjects.     

Amino-Terminal Fragment of Pro-Brain Natriuretic Hormone Identifies Functional Impairment and Right Ventricular Overload in Operated Tetralogy of Fallot Patients

To evaluate the relationship between plasma concentration of amino-terminal fragment of pro-brain natriuretic peptide (NT-proBNP), functional capacity, and right ventricular overload in survivors of tetralogy of Fallot (TOF) repair, we prospectively studied 70 operated TOF patients (44 males, 21 ± 1 years old; mean ± SEM) who underwent, during the same day, echocardiography, cardiac magnetic resonance imaging, neurohormonal characterization (plasma NT-proBNP, catecholamines, plasma renin activity, and aldosterone assay), and cardiopulmonary exercise testing. Forty-eight age- and sex-matched healthy volunteers served as the control group. Compared to controls, maximal workload and peak oxygen consumption (VO₂/kg) were lower in operated TOF patients (p < 0.001), whereas NT-proBNP concentration was elevated (p < 0.001). No difference was found among the other neurohormones. In operated TOF patients, NT-proBNP showed a significant positive correlation with right ventricular (RV) end systolic and end diastolic volumes and RV systolic pressure, and it showed a negative correlation with peak VO₂/kg and RV ejection fraction. From multivariable analysis, NT-proBNP concentration was found to be an independent predictor of peak VO₂/kg, RV end systolic volume, and RV systolic pressure. These results show an association among RV overload, decrease in functional capacity, and cardiac natriuretic peptide expression in operated TOF patients. NT-proBNP plasma assay may be a useful tool for diagnostic purposes and for decision making in this setting.     

The effect of 2% CO2, 100% O2, theophylline and 15% O2 on ‘inspiratory drive’ and ‘effective’ timing in preterm infants

We studied 20 preterm infants (B.W. 1440 ± 80 g (S.E.); G.A. 33 ± 1 wk) to determine the effect of respiratory stimulants and depressants on respiratory output as measured by V_E = V_T · f and V_E = V_T/T_i · T_i/T_tot. These 20 infants were divided in four groups of five infants. Each group received a respiratory stimulant (2% CO₂, 100% O₂ or theophylline) or a respiratory depressant (15% O₂). V_T/T_i is mean inspiratory flow and represents a mechanic translation of neuronal output. T_i/T_tot is a dimensionless number and has been defined as effective timing. Each study consisted of 3–5 min while the infant breathed 21% O₂, followed by 5 min breathing 2% CO₂, 100% O₂ or 15% O₂. The effect of theophylline was assessed 48–72 h after the initial dose. The respiratory stimulants caused an increase in V_T with little or no change in f 15% O₂ produced a decrease in f primarily. According to the newer approach, 2% CO₂, 100% O₂ and theophylline produced an increase in ‘inspiratory drive’ with little or no change in ‘effective’ timing; 15% O ₂ decreased ‘effective’ timing primarily via an increase in T_e. These findings suggest that the paradoxical decrease in ventilation during hypoxia in preterm infants may not be solely dependent on the central depressant effects of O₂. At least in part, the mechanism may be due to a direct action of low O₂ on elements controlling expiratory time.     

The age-dependence of intestinal absorption using d-xylose as an example

In 40 infants the serum concentrations of d-xylose were measured from capillary blood samples up to 300 min after an oral dosage of 0.5 g of d-xylose per kg body weight. The parameters of the absorption kinetics, which are calculated by a digital computer program, showed an age-dependent behavior. Infants up to the age of 2 months have lower maximal serum concentrations compared to older ones because of a larger volume of distribution. The rate constant of invasion k ₁, which serves as a measure for the rate of intestinal absorption and the rate constant of elimination k ₂ were significantly lower in infants up to the age of 2 months compared to older ones. The quotient of k ₁k ₂ was independent of age. The time it took to reach maximal serum concentration was significantly longer in young infants.By adding metoclopramide simultanously to the oral d-xylose doses it could be demonstrated that the slower motility of the gastrointestinal tract in newborns and young infants is not exclusively responsible for the slower rate of absorption of d-xylose. Comparing the absorption rates in 26 infants after different d-xylose dosages a saturation kinetics may be supposed.Supported by Deutsche Forschungsgemeinschaft     

Quantification of left-to-right shunts using aP o 2-electrode cardiac catheter

Summary A rapid, simple and low-cost method is presented for intracardiac left-to-right shunt quantification in children with congenital heart disease. The percentage of shunt is calculated from data obtained by continuousP o ₂ measurement during oxygen inhalation, using a nondisposable intravascularP o ₂-electrode cardiac catheter.These values are compared with those obtained by the dye-dilution method (correlation coefficientr=0.89) and the Fick method (correlation coefficientr=0.98).TheP o ₂ measurement proved reliable for small, medium, and large sized shunts.     

Mechanical Ventilation After Bidirectional Superior Cavopulmonary Anastomosis for Single-Ventricle Physiology: A Comparison of Pressure Support Ventilation and Neurally Adjusted Ventilatory Assist

We evaluated the effects of different respiratory assist modes on cerebral blood flow (CBF) and arterial oxygenation in single-ventricle patients after bidirectional superior cavopulmonary anastomosis (BCPA). We hypothesized that preserved auto-regulation of respiration during neurally adjusted ventilatory assist (NAVA) may have potential advantages for CBF and pulmonary blood flow regulation after the BCPA procedure. We enrolled 23 patients scheduled for BCPA, who underwent pressure-controlled ventilation (PCV), pressure support ventilation (PSV), and NAVA at two assist levels for all modes in a randomized order. PCV targeting large V _T (15 mL × kg^?1) resulted in lower CBF and oxygenation compared to targeting low V _T (10 mL × kg^?1). During PSV and NAVA, ventilation assist levels were titrated to reduce EAdi from baseline by 75 % (high assist) and 50 % (low assist). High assist levels during PSV (PSV_high) were associated with lower PaCO₂, PaO₂, and O₂SAT, lower CBF, and higher pulsatility index compared with those during NAVA_high. There were no differences in parameters when using low assist levels, except for slightly greater oxygenation in the NAVA_low group. Modifying assist levels during NAVA did not influence hemodynamics, cerebral perfusion, or gas exchange. Targeting the larger V _T during PCV resulted in hyperventilation, did not improve oxygenation, and was accompanied by reduced CBF. Similarly, high assist levels during PSV led to mild hyperventilation, resulting in reduced CBF. NAVA’s results were independent of the assist level chosen, causing normalized PaCO₂, improved oxygenation, and better CBF than did any other mode, with the exception of PSV at low assist levels.     

Esophageal electromyography in the diagnosis of gastroesophageal reflux in infants and children

Electromyography (EMG) was performed by drawing a probe out through the esophagus in 38 patients with gastroesophageal reflux (GER) aged 3 weeks to 9 years; 22 asymptomatic infants served as controls. While drawing the probe through the esophagus, the EMG esophageal profile picture was obtained: zones with EMG (L _EMG ) and with EKG only (L _EKG ) were revealed. It was found that the EMG zone in patients with GER was significantly shorter in comparison with controls, i. e., less than one-half the esophageal length. The index L _EMG /L _EKG was always less than 1 in patients with GER and more than 1 in the control group. As a result of the EMG findings, GER was excluded in 7 patients with vomiting, 4 of whom had other causes while 3 proved to be physiological and resolved spontaneously. The method also appeared to be useful for evaluating the effectiveness of GER treatment.     

THE INFLUENCE OF DIFFERENT ENVIRONMENTAL TEMPERATURES ON PULMONARY GAS EXCHANGE and BLOOD GAS CHANGES AFTER BIRTH

Abstract. Tunell, R. (Department of Paediatrics, Karolinska Sjukhuset, Stockholm, Sweden). The influence of different environmental temperatures on pulmonary gas exchange and blood gas changes after birth. Acta Paediatr Scand, 64:57, 1975.–The oxygen uptake (V_o2) and respiratory exchange ratio (R) was determined during the first 20 min and at one and at 2 hours after birth in 16 healthy full-term newborn infants studied in different environmental temperatures. Arterial blood gases and acid-base balance were determined on repeated blood samples from the abdominal aorta. The infants were grouped in a “warm” group (n= 10) where efforts were made to avoid cooling after birth, and a “cold” group (n=6) where a decrease in rectal temperature to a mean value of 35.4^oC at 2 hours occurred. Irrespective of environmental temperature, V_o2 was approximately 10 ml/kg min during the first 8 min after birth, thereafter decreasing to about 6–7 ml/kg min. During the first 8 min the main increase in P_a02 occurred and about 2 ml/kg min of the V₀ was accounted for by changes in oxygen stores after birth. At 16–20 min and at 60 min after birth a negative relationship was found between V_o2 and P_ao2 During the period 8–120 min after birth a close relationship was found between V_o2 and the degree of muscular activity. Within 4–16 min after birth, R values above 1.0 were regularly found simultaneously with the main decrease in P_aco2. In infants kept “cold” a tendency to hyperventilate was found, probably elicited by cold stimuli. The rapid drop in deep body temperature regularly seen after birth could thus not be explained by a limited ability to increase pulmonary gas exchange. A high degree of evaporative heat loss, a relatively low “basal” metabolic rate and a limited response in “non-shivering thermogenesis” seem to be the main reasons for the heat loss after birth.     

Long term developmental outcomes of pre-school age children following laser surgery for twin-to-twin transfusion syndrome

BackgroundLaser therapy is now a well recognised treatment for twin-to-twin transfusion syndrome (TTTS). We investigated the early childhood neurodevelopmental outcome of children post laser treatment for TTTS in our centre.MethodsChildren of women who had laser therapy for TTTS between March 2006 and June 2008 were assessed at 30–69 months of age with WPPSI-III and a general health questionnaire. Major neurodevelopmental impairment (NDI) was reported as IQ < 70 or cerebral palsy (CP). Borderline cognitive impairment was defined by IQ 70–79.ResultsAmongst the 37 pregnancies treated, 62 infants were discharged home and the overall foetal survival rate was 84%. A total of 50 children (84%) from 31 pregnancies were assessed. Average age at assessment was 47 months. Two children with late treatment of congenital hypothyroidism were excluded. The majority of pregnancies were Quintero Stage III (74%). There was a significant trend for worse outcome with higher Quintero stage. The average gestational age at birth was 32 weeks. The majority (39, 78%) of children were found to be neurodevelopmentally normal; 9 (18%) had borderline cognitive development; and 2 (4%) had a major NDI, including one with cerebral palsy (2%).ConclusionsThere was a modest level of neurocognitive impairment post laser therapy for TTTS, mainly borderline cognitive development, lesser so major NDI. There was a low incidence of cerebral palsy. Routine developmental and neurological follow-up of these children is recommended.