Cycle Ergometer Tests in Children With Cystic Fibrosis: Reliability and Feasibility

The aim of this study was to assess the reliability and feasibility of cycle ergometer tests in young children with cystic fibrosis (CF). Children with CF aged 6–11 years and with stable lung disease performed two cycle ergometry tests (intermittent sprint and continuous incremental) on two occasions 1 week apart. Reliability was assessed using repeated‐measures ANOVA. Bias was considered to be significant at P < 0.05 level and a coefficient of variation (CV) below 10% was considered acceptable. Feasibility and acceptability data were also collected. Sixteen children with CF completed the study: (9M:7F), 8.7(1.8) years, FEV₁%predicted: 88.1(17.4). Power measurements recorded during the intermittent sprint test demonstrated significant bias over days (P < 0.05) and CVs were between 10% and 15%. Peak work capacity recorded during the continuous incremental test was reliable (bias P < 0.05, CV < 10%), as was heart rate and SpO₂ recorded during both tests (bias P < 0.05, CV < 10%). No problems were experienced in administering the tests and all children completed both tests on two separate occasions. There was a mixed response to questions on acceptability of tests. This is the first study to provide information on the reliability of performance measures recorded during an intermittent sprint protocol (peak power) and a continuous incremental cycle ergometry (peak work capacity) in children with CF. Pediatr Pulmonol. 2012; 47:1226–1234. © 2012 Wiley Periodicals, Inc.     

Plasma Arginine Levels and Blood Glucose Control in Very Preterm Infants Receiving 2 Different Parenteral Nutrition Regimens

Background: Improving parenteral nutrition (PN) amino acid (AA) intake in very preterm infants is associated with less hyperglycemia. AAs stimulate newborn insulin secretion with arginine, demonstrating a specific effect. We hypothesized that low arginine levels would be associated with increased insulin‐treated hyperglycemia and higher mean daily blood glucose levels in very preterm infants. Methods: We performed a secondary analysis on previous study data comparing high‐protein/calorie PN (HPC‐PN) and control groups in infants <29 weeks’ gestation. Infants were substratified (within original groups) according to high (highARG) and low (lowARG) plasma arginine levels on days 8–10 using a reference population‐derived threshold for high/low arginine (57 µmol/L). Daily protein, arginine, carbohydrate intake, mean daily blood glucose, and insulin treatment data from the first 15 days of life were collected. Results: Control group infants (n = 60) were stratified into lowARG (n = 41) and highARG (n = 19) groups. There were no differences in basic demographic data or carbohydrate intake. LowARG infants had higher mean daily blood glucose levels (P < .05) and a trend to more insulin treatment on days 6–10. HPC‐PN group infants (n = 55) were stratified into lowARG (n = 33) and highARG (n = 22) groups. LowARG infants had lower gestation and birth weight and were sicker than highARG infants. There were no differences in carbohydrate intake. LowARG infants had higher mean daily blood glucose levels (P < .01) and more insulin treatment (P < .01) on days 1–5 and 6–10. Insulin‐treated hyperglycemia was also associated with low plasma glutamine levels. Conclusion: Low plasma arginine levels (≤57 µmol/L) in very preterm infants are associated with poorer blood glucose control.