[Positioning of umbilical vein catheter with ECG-guided technique: randomized study]. / Posizionamento del catetere ombelicale venoso con tecnica ECG-guidata: studio randomizzato.

GOAL: To evaluate the effectiveness of electrocardiography-guided technique to aid in the correct positioning of umbilical vein catheters. DESIGN: A prospective, randomized controlled study. METHODS: Term and preterm newborns who required an umbilical venous catheter were managed by an ECG-guided technique (group A) or by a conventional method (group B). Correct positioning was defined by a chest-X-ray when the catheter tip was located above the diaphragm and outside the right atrium. For the ECG-guided technique we utilized a conductive device Vygocard (Medival, Padova) inserted in a 3-way stopcock connected with the catheter. The catheter was inserted under ECG observation until the appearance of a tall P-wave in lead III, which indicated the tip was within the right atrium. The catheter was then withdrawn until the P wave size returned to normal. RESULTS: We enrolled 44 patients (16 F, 28 M). Median gestational age (GA) and birth weight (BW) were 34 weeks (range 26-41) and 2130 g. (590-3870), respectively. Sex distribution, GA, BW and Apgar scores were not different between patients in group A (n = 22) and group B (n = 22). Catheters could not be advanced till the estimated insertion depth in 11 patients (A = 5, B = 6). In the remaining 33 patients, correct tip placement was more frequent in group A (88%) compared with group B (50%) (p = 0.021 by Fisher's exact test). No side effects specific to the ECG-guided method were noted. CONCLUSIONS: The ECG-guided technique seems to be a safe and effective method for the proper placement of umbilical vein catheters in newborns.

Exercise performance in children with asthma: is it different from that of healthy controls?

Exercise tolerance and possible limitation in work capacity of asthmatic children is still a matter of debate. The aim of this study was to compare ventilation and gas exchange response to exercise of asthmatic children with that of healthy controls. Exercise performance was evaluated in 80 children with mild-to-moderate asthma, aged 7-15 yrs, and in 80 healthy controls matched for age, height, weight and habitual level of physical activity. The children performed a maximal exercise test on a treadmill, during which oxygen uptake (V'O2), carbon dioxide output (V'CO2) and minute ventilation (V'E) were measured continuously. No premedication was given to the asthmatic children. Forced expiratory volume in one second (FEV1) at rest was 93+/-11% of predicted in asthmatic children and 95+/-9% pred in controls. After the run, the mean fall in FEV1 was 13.9% (range 0-57%) and 1.6% (0-9%), respectively (p<0.001). The two groups achieved similar maximum oxygen uptake (V'O2,max) ((mean+/-SD) 40.3+/-8.4 and 42.6+/-9.6 mL x min(-1) x kg(-1) in asthmatics and controls, respectively; NS) and maximum minute ventilation output (V'E,max) (42.9+/-14.8 and 45.7+/-14.9 L x min(-1) respectively; NS). The kinetics of V'O2, V'CO2 and V'E during the test revealed no differences between the two populations. Moreover, anaerobic threshold and oxygen pulse were the same in the two groups. Asthmatics showed a ventilatory pattern with lower respiratory frequencies and greater tidal volumes during the run. These results suggest that asthmatic children can achieve a level of exercise performance similar to that of healthy children, provided that they have a comparable level of habitual physical activity. The only difference found concerned the ventilatory pattern of the asthmatic children, which was characterized by a reduced respiratory frequency and greater tidal volume at the same minute ventilation. The level of physical conditioning was found to be the main determinant of exercise tolerance for children with controlled asthma.

Factors limiting exercise performance in long-term survivors of bronchopulmonary dysplasia.

The long-term impairment of pulmonary function during exercise was assessed in 12 children, aged 6 to 12 yr, who developed BPD after prematurity (gestational age 30 +/- 2 wk [mean +/- SD] and birth weight 1,400 +/- 335 g) and 16 age-, sex-, and physical activity-matched healthy children born at term, who served as controls. The children performed pulmonary function tests at rest and a maximal stepwise exercise on a treadmill. Oxygen consumption (VO2), carbon dioxide output (VCO2), and minute ventilation (VE) were monitored during the run. Baseline mean spirometric values (% of predicted) were in the normal range for both groups but were lower in BPD children with respect to control children (p < 0.05). At rest, arterial oxygen saturation (SaO2) was > or = 98% in all BPD children, but at peak exercise, 4 of them had a SaO2 fall > or = 4%. The postexercise FEV1 fall, with respect to the baseline, was 8 +/- 6%, in BPD and 2 +/- 1% in control children (p < 0.01). Maximum VO2 and VE were significantly lower in BPD children with respect to the control group (25.2 +/- 10.3 versus 37.1 +/- 10.4 ml/min/kg and 20.8 +/- 9.4 versus 30.7 +/- 7.9 L/min, respectively, both p < 0.01). Also, at submaximal levels of exercise dynamic, VO2 and VE responses were significantly lower in the BPD group (ANOVA, p < 0.001), with a ventilatory pattern characterized by lower tidal volumes. Anaerobic threshold was 20.6 +/- 9 in BPD and 28.8 +/- 8.6 ml O2/min/kg in healthy children (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of disodium cromoglycate on ventilation and gas exchange during exercise in asthmatic children with a postexertion FEV1 fall less than 15 percent.

The purpose of this study is to evaluate the effect of disodium cromoglycate (DSCG) on gas exchange and ventilation during incremental exercise in asthmatic children with an FEV1 fall less than 15 percent from the baseline after the exercise. Seventeen children (aged 8 to 14 years) with a history of mild to moderate asthma but no clinical and spirometric evidence of exercise-induced asthma (EIA) underwent two maximal exercise tests in a randomized order: test A without premidication and test B after inhalation of DSCG, 40 mg. To evaluate the effect of DSCG on normal airways, nine healthy children performed the same exercise protocol. Pulmonary function was normal at rest and after treadmill exercise test (the mean postexercise fall in FEV1 was 5.9 percent in test A and 1.5 percent in test B). Gas exchange, minute ventilation (VE) and heart rate (HR) were monitored during running in both tests. In the asthmatic subjects, there were no differences in oxygen uptake (VO2), carbon dioxide output (VCO2), and VE at rest between the two tests. During exercise, VE, VO2, VCO2, and energy cost (EC[O2 ml.kg-1.m-1]) of running in the asthmatic subjects were significantly lower in test B than in test A (analysis of variance, p < 0.01) for comparable work rates. Maximal minute ventilation (VEmax) was significantly higher in test A (46.9 +/- 14.6[+/- SD]L.min-1) than in test B (43.2 +/- 14 L. min-1; p < 0.05). We found no significant effect of DSCG on gas exchange and ventilation during exercise in the healthy children (VEmax 47.8 +/- 25 and 48.4 +/- 25 L.min-1 in test A and B, respectively). In conclusion, premedication with DSCG appears to decrease the ventilatory cost of exercise in asthmatic children who do not present a substantial fall in FEV1 after an exercise test without pretreatment.

Gas exchange during exercise in diabetic children.

The purpose of this study was to evaluate the cardiorespiratory and metabolic response to exercise in 33 children, aged 9 to 15 years, affected by type I diabetes mellitus, in comparison with 47 age-, sex-, weight-, and height-matched healthy children. All diabetic children were on a mixed split-dose insulin regimen, consisting of both regular and long-acting insulin in the morning and evening. The last insulin injection was administered on average 6 hours before the test. The mean duration of diabetes mellitus was 5.0 +/- 3.1 years. The metabolic control was evaluated on the basis of HbA1 levels (mean, 8.9 +/- 1.8%). Pulmonary function tests and progressive exercise tests on the treadmill were performed. Gas exchange, ventilation, and heart rate (HR) were monitored during the tests. The O2 pulse (VO2/HR) was calculated. There was no difference in the baseline oxygen uptake (VO2) between the diabetic children and the control group. VO2 peak was significantly lower (P less than 0.01) in the diabetic adolescents (41.2 +/- 5.9 mL/min/kg) compared to control subjects (46.3 +/- 9.6 mL/min/kg) and it was achieved at an earlier (P less than 0.01) time of run (7.5 +/- 1.8 vs. 9.1 +/- 2.8 min). Anaerobic threshold and minute ventilation were similar in the two groups. The O2 pulse throughout the test was significantly lower (ANOVA, P less than 0.001) in the diabetic group compared to the controls. No differences were found in resting and post-exercise spirometric values. In conclusion, our study shows that well-controlled diabetic adolescents have a reduced working capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise performance in very low birth weight children at the age of 7-12 years.

Fifteen very low birth weight children, 9 appropriate for gestational age (AGA, mean birth weight 1302 +/- 164 g) and 6 small for gestational age children (SGA, mean birth weight 1263 +/- 117 g), were studied at the age of 7-12 years, and compared to a group of 26 healthy, age-, sex-, and height-matched children born at term. None of the VLBW children had developed chronic bronchopulmonary disease. Pulmonary function tests and progressive exercise tests on a treadmill were performed. Forced vital capacity, forced expiratory volume at 1 s and forced expiratory flow between 25% and 75% of vital capacity were normal for all subjects. No differences were found in maximum oxygen consumption, anaerobic threshold and maximal heart rate between the AGA and SGA children and the respective controls. Both in the AGA and SGA subgroups, the pre-exercise oxygen uptake results were comparable to those of the controls. In the SGA subgroup the energy cost of running was significantly higher with respect to the controls, while no difference was found between the AGA and the control children. In conclusion, children with birth weight less than 1501 g have normal values of aerobic fitness. In SGA children the efficiency of running is slightly reduced.

Effect of inhaled disodium cromoglycate and albuterol on energy cost of running in asthmatic children.

The purpose of this study is to evaluate the effect of disodium cromoglycate and albuterol on energy cost of running, gas exchange, and ventilation during maximal exercise in children with exercise-induced asthma (EIA). Twelve children (7.1-15.5 years old) with a history of mild to moderate asthma and EIA performed three maximal exercise tests on a treadmill: 1) test A, without premedication; 2) test B, after premedication with inhaled disodium cromoglycate (DSCG) (40 mg); 3) test C, after premedication with inhaled albuterol (200 micrograms). The energy cost of running was calculated at each minute of exercise. None of the children were limited by dyspnea during the run. The post-exercise fall in FEVi after test A was greater than 20% for each child, the mean fall being 32.8 +/- 11.6%, in comparison with 12.6 +/- 8.9% after test B (P less than 0.001) and 2.5 +/- 5.3% after test C (P less than 0.001). There was no difference in the baseline oxygen uptake for the three tests. Maximum oxygen uptake (VO2 peak) decreased from 43.9 +/- 7.7 mL/min/kg in test A to 37.7 +/- 6.0 mL/min/kg in test B (P less than 0.01) and 39.1 +/- 7.2 mL/min/kg in test C (P less than 0.05). Ventilatory anaerobic threshold in tests B and C was significantly lower than in test A (P less than 0.01). Ventilation (L/min) and energy cost of running (O2 mL/kg/m) were significantly lower in tests B and C than in test A at comparable times. Running time was longer in B and C (P less than 0.05) with respect to A.(ABSTRACT TRUNCATED AT 250 WORDS)

Gas exchange during exercise in obese children.

Twenty-three obese children, aged 9 to 14 years, ranging in percentage overweight from 26% to 83% (median 51.6% +/- 16.3%), and 37 normal-weight children, matched for sex, age and height, performed a maximal exercise test on a treadmill. Cardiorespiratory performance was assessed by determination of the ventilatory anaerobic threshold (VAT) expressed in ml O2/min per kg and as a percent of maximal oxygen uptake (% VO2max). VAT and VO2max related to body weight were significantly lower (P less than 0.01) in the obese than in the normal-weight children. VAT % VO2max was similar in the two groups. A significant correlation was found between VAT and VO2max both in the obese (r = 0.85) and in the control groups (r = 0.79). The habitual level of physical activity was lower in the obese subjects compared to the control subjects (P less than 0.001). In conclusion our study shows that physical fitness of overweight children is quantitatively lowered and that it can be assessed by VAT. VAT does not require a maximal test and is particularly useful in the ergometric study of subjects with exercise intolerance.

A comparison of two noninvasive methods in the determination of the anaerobic threshold in children.

Seventy children, ranging in age from 7 to 14 years, performed a maximal exercise test on a treadmill with determination of the anaerobic threshold (AT) by two methods: (1) with the gas exchange method the ventilatory anaerobic threshold (VAT) was identified by the increase in the ventilatory equivalent for O2 uptake without a concomitant increase in the ventilatory equivalent for CO2 output and (2) with the method proposed by Conconi, the AT was taken at the point beyond which the increase in work intensity exceeded the increase in heart rate and the linearity of the work rate/heart rate relationship was lost. The AT values measured with the two methods were correlated (r = 0.80, P less than 0.001). This result confirms, also in children, the validity of the simple Conconi method: It can be used particularly for the determination of the individual optimal intensity of training.