Cystic fibrosis: nutritional consequences and management

Comparison of the TriTrac-R3D accelerometer and a self-report activity diary with heart-rate monitoring for the assessment of energy expenditure in children

Determining total energy expenditure (EE) in children under free-living conditions has become of increasingly clinical interest. The aim of this study was to compare three different methods to assess EE triaxial accelerometry (TriTrac-R3D; Professional Products, Division of Reining International, Madison, WI, USA), activity diary and heart-rate (HR) monitoring combined with indirect calorimetry (IC). Twenty non-obese children and adolescents, aged 5.5 to 16.0 years, participated in this study. Results from the three methods were collected simultaneously under free-living conditions during the same 24 h schoolday period. Neither activity diary (5904 (SD 1756) KJ) NOR THE TRITRAC-R3D (6389 (sd 979) kJ) showed statistical differences in 24 h total EE compared with HR monitoring (5965 (sd 1911) kJ). When considering different physical activity (PA) periods, compared with HR monitoring, activity diary underestimates total EE during sedentary periods (P<0·001) and overestimates total EE and PA-EE during PA periods (P<0·001) because of the high energy cost equivalence of activity levels. The TriTrac-R3D, compared with HR monitoring, shows good agreement for assessing PA-EE during PA periods (mean difference +0·25 (sd 1·9) kJ/min; 95 % CI for the bias -0·08, 0·58), but underestimates PA-EE and it does not show good precision during sedentary periods (-0·87 (sd 1·4) kJ/min, P<0·001). Correlation between the vector magnitude generated by the TriTrac-R3D accelerometer and EE of activities derived from HR monitoring is high. When compared with the HR method, the TriTrac-R3D and activity diary are not systematically accurate and must be carefully used for the assessment of children's EE depending on the purpose of each study.

Cystic fibrosis: nutritional consequences and management

Life expectancy for patients with Cystic Fibrosis (CF) has steadily improved during the last three decades, and death in childhood is now uncommon. Nutrition is a critical component of the management of CF, and nutritional status is directly associated with both pulmonary status and survival. Expert dietetic care is necessary, and attention must be given to ensuring an adequate energy intake in the face of demands which may be increased by inadequately controlled malabsorption, chronic broncho-pulmonary colonisation by bacteria and fungi, exacerbations of acute lung infection, impaired lung function, and the need for rehabilitation, repair and growth. Pancreatic enzyme replacement therapy (PERT) is needed by up to 90% of CF patients in Northern Europe, where the 'severe' mutation deltaF508 predominates, but a smaller proportion in Mediterranean countries and elsewhere, because pancreatic insufficiency is one of few features of CF which correlate with genotype. Complications of CF including liver disease and CF-related diabetes pose further challenges. In addition, deficiency of specific nutrients including fat soluble vitamins (particularly A, E and K) essential fatty acids and occasionally minerals occur for a variety of reasons. Osteopenia is common and poorly understood. Liver disease increases the likelihood of vitamin D deficiency. Glucose intolerance and diabetes affect at least 25% of CF adults, and the diabetes differs from both types 1 and 2 diabetes mellitus, but it inversely correlates with prognosis. Management consists of anticipating problems and addressing them vigorously as soon as they appear. Supplements of vitamins are routinely given. Energy supplements can be oral, enteral or, rarely, parenteral. All supplements, including PERT, are adjusted to individual needs.

[Technical aspects and relevance of energy expenditure and physical activity assessment in clinical research for cystic fibrosis patients]

Cystic fibrosis (CF) is characterized by deteriorating lung function and mal-digestion, which result in growth failure and/or under-nutrition. Several factors, alone or combined, contribute to malnutrition in CF: poor energy intake, elevation of energy loss as a result of malabsorption, increasing resting energy expenditure due to genetic mutation and/or pulmonary exacerbation. Several techniques have been used to assess energy expenditure and physical activity in order to better understand mechanisms of malnutrition in CF and follow therapeutic interventions. Indirect calorimetry (IC) studies have shown that resting energy expenditure (REE) was 10-22% higher than predictive values. This increase could be attributed to chronic inflammation as a result of Pseudomonas aeruginosa (PA) infection. Indeed, intravenous antibiotic therapy decreases REE. Doubly labelled water technique and heart rate monitoring calibrated against IC techniques shows that total energy expenditure (TEE) was not different than in healthy children. Physical activity level assessed by the ratio TEE-REE is also not different between CF of healthy children. Recently, new accelerometry technics, easier to use and less invasive have been successfully used in order to assess physical activity level in CF. Precise and ambulatory assessment of energy expenditure and physical activity permit to check and adapt dietary allowances in CF. These techniques could be simultaneously used and be helpful to assess efficacy of intervention studies.

Energetic cost of physical activity in cystic fibrosis children during Pseudomonas aeruginosa pulmonary exacerbation

Chronic pulmonary infection by Pseudomonas aeruginosa is observed in 50% of patients with cystic fibrosis and requires the use of recurrent intravenous therapy. A decrease of resting energy expenditure (REE) and an increase of physical activity (PA) after intravenous anti-P. aeruginosa therapy (IVAT) is observed while total energy expenditure (TEE) does not change. A decrease in the energetic cost of physical activity (ECPA) could be hypothesized but has never been studied. Our aim was to assess the evolution of ECPA after home IVAT in both standardized condition at hospital and in free-living condition twice before and after IVAT. Sixteen CF patients (nine boys, seven girls) chronically colonized by P. aeruginosa with a mean age of 12.1+/-2.3 years (range 7.1-14.6) were studied before and after IVAT. Each patient passed throughout a visit in hospital: weight, height and fat-free mass were measured. Then, energy expenditure (EE) measured by indirect calorimetry and heart rate (HR) were simultaneously recorded at different levels of PA: REE, and at different intensity of physical activities on a cycloergometer using an incremental increase of the power brake force. Physical activity energy expenditure (PAEE) was computed in laboratory condition using PAEE=EE-BEE (basal energy expenditure). Linear regression between PAEE and power brake force was fitted for each patient before and after IVAT. ECPA in standardized conditions was compared at different range of power brake force using area under the curve (AUC). After coming back at home, 24 h TEE using the heart rate monitoring technique and PA by triaxial accelerometry were simultaneously measured in free-living condition for 24 h during a school day. ECPA in free-living conditions was compared by the ratio PAEE:PA where PAEE=DEE-REE (DEE=daily energy expenditure). After IVAT, median AUC between 60 and 90 W in standardized condition decreased significantly by -15.4% (median 14.9, range 8.8-30.3 vs. median 12.6, range 8.5-17.6; P<0.05, Wilcoxon rank test) while the decrease for lower range of power work load did not reach significance. Spearman correlation was significant between variations of forced expiratory volume in 1 s and variation of AUC at 30-60 W before and after IVAT in standardized condition. In free-living conditions, ratio PAEE/PA did not vary significantly (median 3.4, range 1.6-6.4 vs. median 2.8, range 1.4-4.8; NS). Our data demonstrate a decrease of ECPA after IVAT in standardized conditions for moderate level of PA (60-90 W), but not in free-living conditions. The decrease of ECPA was probably due to a decrease in the energetic cost of breathing after IVAT, that is particularly relevant to promote PA in CF patients.

Impact of intravenous antibiotic therapy on total daily energy expenditure and physical activity in cystic fibrosis children with Pseudomonas aeruginosa pulmonary exacerbation

Resting energy expenditure (REE) increases during pulmonary exacerbation by Pseudomonas aeruginosa in cystic fibrosis (CF) patients, and decreases after i.v. anti-Pseudomonas aeruginosa antibiotic therapy (IVAT). However, the impact of IVAT on total energy expenditure (TEE) is unknown. The aim of this study was to assess the changes in TEE and its main components after IVAT administered at home. Body composition measured by skinfold thickness and bio-impedance analysis, energy intake (EI) assessed by a weekly diary, REE measured by indirect calorimetry (IC), TEE assessed by a technique using 24-h heart-rate monitoring method and physical activity (PA) monitored using an activity diary (AD) were assessed in 16 patients (9 boys and 7 girls) aged 12.1 +/- 2.3 y (range, 7.1-14.6 y), before and after 28 +/- 4 d including a 14-d IVAT course. After IVAT, weight increased significantly by 1.9% (32.1 +/- 7.5 versus 32.7 +/- 7.6 kg; p < 0.05), while fat mass and fat free mass increased non significantly. EI increased by 4.6% (10,797 +/- 3039 versus 11320 +/- 3074 kJ/d; p < 0.05). TEE was not affected by IVAT (7014 +/- 1929 versus 7081 +/- 1478 kJ/d) whereas REE decreased by 4.1% (5295 +/- 909 versus 5093 +/- 837 kJ/d; p < 0.05), resulting in 9.3% increase in PA assessed by AD converted to metabolic equivalent tasks (MET) (37.0 +/- 3.1 versus 40.7 +/- 4.5 MET; p < 0.05). The improvement in nutritional status after IVAT is not related to a decrease in TEE, but probably to an increase in EI and a decrease of REE after IVAT. After IVAT, the reduction in REE is probably compensated by an increase in PA in CF patients.

Longitudinal investigation of energy expenditure in infants with cystic fibrosis

OBJECTIVE

To determine when energy expenditure becomes elevated in infants with cystic fibrosis (CF).

DESIGN

Longitudinal studies of total energy expenditure (TEE) using doubly labeled water were conducted in infants identified with CF by newborn screening through the first year of life.

SETTING

Hospital and community based studies in Denver, Colorado, USA and Cambridge, UK.

RESULTS

Eight of the 12 infants enrolled had begun enzyme therapy but were clinically asymptomatic. Four of the 12 infants were heterozygous for the delta F508 mutation, however no difference was seen in TEE from the remaining homozygous infants. TEE was compared to control cohorts at 2, 6 and 12 months of age. There was no difference from the control groups in TEE/kg fat free mass (FFM)/day at 2 months. However, by 6 months of age TEE/kg FFM/day in infants with CF exceeded that of age-matched controls by 25% (P<0.001). This elevation in TEE continued at 12 months of age exceeding that of controls by 30% (P<0.05).

CONCLUSIONS

These results indicate that infants with CF have increased energy needs by 6 months of age and that early diagnosis alone does not prevent the development of increased caloric requirements. These findings emphasize the need for close nutritional monitoring to prevent suboptimal growth during infancy in this population.

SPONSORSHIP

This research was supported by grant number 5 MO1 RR00069, General Clinical Research Centers Program, National Center for Research Resources, NIH.

Contamination of gastrostomy feeding systems in children in a home-based enteral nutrition program

BACKGROUND

There are few data concerning the risk of contamination of enteral feeding systems via gastrostomy in children, and none for conditions that pertain to home-based care.

METHODS

To investigate the risk of contamination of enteral feeding systems during the home-based care of 20 children receiving gastrostomy tube feeding, five samples were taken for analysis: two samples before the enteral feeding period (gastrostomy, enteral feeding system) and three after this period (gastrostomy, distal giving set, liquid remained in container). Microorganisms were identified and counted. Different factors were studied to elucidate their role in bacterial colonization: acid suppressive therapy, gastrostomy tube or button, hanging feeding time, rate of enteral feeding, gastric pullulation and retrograde contamination, manipulation error, and use of open or closed enteral feeding systems.

RESULTS

Overgrowth was defined as a microorganismal load exceeding 10(4) colony-forming units (cfu)/mL. Overgrowth was present in 85% of gastrostomy samples before enteral nutrition started. Most microorganisms belonged to gastric flora. Some bacteria had an environmental origin or derived from cutaneous flora. Forty-five percent of the lines showed overgrowth at the end of enteral nutrition period, mainly with the same microorganism found in the gastrostomy. Closed enteral bags remained sterile, even if manipulation error occurred. Duration, rate of enteral feeding, and acid suppression treatment were not risk factors for overgrowth.

CONCLUSIONS

Retrograde contamination of gastrostomy feeding systems occurs frequently. The preferential use of closed enteral feeding systems is recommended for home-based enteral nutrition programs.