Growth failure in infants with bronchopulmonary dysplasia: nutrition and elevated resting metabolic expenditure

The mechanisms underlying growth failure in infants with bronchopulmonary dysplasia are poorly understood. Thirteen infants with bronchopulmonary dysplasia at 6 months of corrected age and 12 full-term healthy control infants matched for age or size were studied. Resting oxygen consumption was measured during natural sleep, and an estimation of the resting metabolic expenditure by indirect calorimetry was performed. Growth parameters were measured, and a nutritional profile including dietary intake, stool analysis, and serum albumin, cholesterol, glucose, and prealbumin was obtained. Seven of the 13 infants with bronchopulmonary dysplasia had growth failure (defined as length and weight less than the tenth percentile of the Babson growth curves). These infants had lower birth weight, lower gestational age, and a greater number of days spent in supplemental oxygen or on mechanical ventilation. There was no statistical difference between the bronchopulmonary dysplasia-growth failure and bronchopulmonary dysplasia-normal growth infants for dietary intake or stool or serum analyses. However, serum prealbumin showed a significant linear correlation with body weight in infants with bronchopulmonary dysplasia. Resting metabolic expenditure was elevated in infants with bronchopulmonary dysplasia with growth failure and was inversely correlated with body weight in all infants with bronchopulmonary dysplasia. Thus, infants with bronchopulmonary dysplasia and growth failure have increased metabolic demands and decreased prealbumin values suggesting a relative state of protein-calorie malnutrition.     

Total energy expenditure in infants with bronchopulmonary dysplasia is associated with respiratory status

Growth failure is a well-known problem in infants with bronchopulmonary dysplasia (BPD). We studied BPD infants' total daily energy expenditure (Ee), nutritional balance, and growth in relation to their past and current clinical status. Applying the doubly labelled water technique, Ee was measured in nine preterm infants with BPD receiving supplemental oxygen (postnatal age 61 ± 13 days) and nine matched controls (36 ± 21 days) during a 6-day period. Energy and protein balance, past and present respiratory status, and growth were assessed as well. The results show that Ee was higher in the BPD infants compared to controls (73 ± 9 vs 63 ± 8 kcal/kg/day, P < 0.05), but their faecal energy loss was lower (P < 0.01). Weight gain, energy intake, energy cost of growth, protein retention, and physical activity were not different. The respiratory frequency (RR) in the BPD infants was elevated in comparison with controls (P < 0.01). Within the BPD group, RR was positively correlated with energy expenditure (regression equation: Ee [kcal/kg/day] = 26.3 + 0.71*RR [min⁻¹]; r ² = 0.82, P < 0.001), and was the single most significant determinant of Ee. Conclusion Total energy expenditure in BPD infants is elevated and is strongly associated with their respiratory status. These findings could be of practical value for the nutritional management in infants with severe BPD. Received: 17 January 1996 / Accepted: 23 July 1996     

Weaning oxygen in infants with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease commonly seen in preterm infants as the sequelae following respiratory distress syndrome. The management of evolving BPD aims to minimise lung injury and prevent the impact of hypoxia and hyperoxia. Proposed morbidities include respiratory instability, pulmonary hypertension, suboptimal growth, altered cerebral oxygenation and long-term neurodevelopmental impairment. The ongoing management and associated morbidity present a significant burden for carers and healthcare systems. Long-term oxygen therapy may be required for variable duration, though there is a lack of consensus and wide variation in practise when weaning supplemental oxygen. Furthermore, a shift in care towards earlier discharge and community care underlines the importance of a structured discharge and weaning process that eliminates the potential risks associated with hypoxia and hyperoxia. This review article describes recent evidence outlining oxygen saturation reference ranges in young infants, on which structured guidance can be based.     

Improving pulmonary function does not decrease oxygen consumption in infants with bronchopulmonary dysplasia

To determine whether the high oxygen consumption VO2 in infants with bronchopulmonary dysplasia (BPD) is caused by increased mechanical power of breathing, and if improvement of pulmonary mechanics would reduce mechanical power of breathing and VO2 we gave 16 infants with oxygen-dependent BPD at 19.5 +/- 10.7 (mean +/- SD) weeks of age placebo, theophylline, and orally administered diuretics or theophylline plus diuretics. Pulmonary mechanics, mechanical power of breathing, and VO2 were measured at the beginning and end of each study period. In the placebo group, all infants had elevated VO2 (7.4 +/- 1.4 mL/kg/min) and carbon dioxide production (6.6 +/- 1.2 mL/kg/min), increased airway resistance (59 +/- 30 cm H2O/L/sec), decreased dynamic compliance (0.073 +/- 0.024 mL/cm H2O/cm), increase respiratory rate (52 +/- 11), and increased mechanical power of breathing (2.22 +/- 1.05 kg.cm/kg/min). Treatment with theophylline, diuretics, and theophylline plus diuretics resulted in a significant improvement in pulmonary mechanics and mechanical power of breathing, but not in VO2. These results suggest that the increased VO2 in infants with BPD is not secondary to increased mechanical power of breathing.     

Measurement of resting energy expenditure in infants

OBJECTIVE: The method for measurement of basal metabolic rate (BMR) using indirect calorimetry in adults is well established but is impractical in infants. METHODS: In this prospective study energy expenditure was measured using indirect calorimetry in 14 infants when sleeping and when lying quietly awake. RESULTS: Sleeping metabolic rate (SMR) was lower than energy expenditure (EE) measured in the same infants in a quiet resting state (mean difference [SD]: 297 [162] kJ/d; P < 0.005; 55 [33.4] kJ/kg per day; P < 0.005). The correlation within individuals suggests that these differences are related to the level of arousal. Awake EE, but not SMR, was significantly greater than estimated BMR using the FAO/WHO/UNU predictive equation. CONCLUSIONS: In infants, the level of arousal during measurement of EE can significantly impact on the interpretation of EE results. A standardized method for the measurement of EE in infants using indirect calorimetry is proposed.     

Metabolic rate and energy balance in infants with bronchopulmonary dysplasia

To determine energy use and growth of infants with bronchopulmonary dysplasia (BPD), we studied metabolic rate and energy balance in five infants with stage III-IV BPD (birth weight 1309 +/- 530 gm, gestational age 32 +/- 3 weeks, postnatal age 59.8 +/- 14.2 days) and in five control infants (birth weight 1540 +/- 213 gm, gestational age 33 +/- 2 weeks, postnatal age 42.0 +/- 4.2 days). Infants with BPD had significantly lower energy intake but higher energy expenditure than did control infants. Weight gain and energy cost of growth were significantly less in BPD infants than in control infants, as were urine output and output/intake ratio. We conclude that infants with BPD (1) absorbed caloric intake as well as did normal control infants, (2) had low energy intake and high energy expenditure, resulting in poor weight gain, and (3) had low energy cost of growth, suggesting an alteration in composition of tissue gain, with relatively high water content.     

Home oxygen promotes weight gain in infants with bronchopulmonary dysplasia

To study the effect of oxygen therapy on weight gain in bronchopulmonary dysplasia (BPD), the growth of 22 infants with BPD enrolled in a premature follow-up clinic and home oxygen program was examined retrospectively. Mean gestational age was 28 weeks (range, 26 to 33 weeks) and mean birth weight was 1110 g (range, 680 to 2000 g). After discharge, infants were monitored monthly to maintain transcutaneous oxygen tension over 55 mm Hg and/or pulse oximeter oxygen saturation over 92%. With appropriate home oxygen, all 22 infants grew as well as healthy, full-term infants (mean, 40th percentile; range, tenth to 80th percentile) when ages were corrected for prematurity. Parents discontinued oxygen therapy inappropriately in seven infants, and all seven experienced significant deceleration in weight gain. When home oxygen therapy was resumed, their weight gain improved, but the infants never regained their original percentiles during the study period. The 15 infants who continued home oxygen therapy maintained their original weight percentiles throughout the study period. These data support an important role for home nasal cannula oxygen in promoting weight gain in selected infants with BPD.     

Pulmonary vascular response to oxygen in infants with severe bronchopulmonary dysplasia

The cardiac catheterization data of six infants with bronchopulmonary dysplasia (BPD) were reviewed to examine the responsiveness of their pulmonary vascular beds to changes in oxygen tension. The infants were studied because of slow recovery from their oxygen requirements and clinical evidence of persistent pulmonary hypertension. All were receiving home oxygen therapy and had abnormal chest radiographs and right ventricular hypertrophy by ECG at the time of catheterization (mean age, 25 months). All infants had mean pulmonary artery pressure greater than 25 mm Hg in room air, with a mean of 48 mm Hg. All decreased mean pulmonary artery pressure by at least 10 mm Hg when placed in high levels of inspired oxygen (FiO2 greater than 80), with a mean pulmonary artery pressure of 25 mm Hg. This represented a significant decrease in mean pulmonary artery pressure from room air pressures (P less than .005). Mean pulmonary artery pressure was also measured in three infants who were breathing supplemental oxygen by nasal cannula at flow rates similar to levels used for outpatient therapy. Most of the reduction in mean pulmonary artery pressure that occurred at high FiO2 occurred at these lower flow rates of supplemental oxygen. It is concluded that infants with bronchopulmonary dysplasia who have pulmonary hypertension generally have reactive pulmonary vascular beds, responsive to supplemental oxygen. Continuous oxygen therapy by nasal cannula may be useful in the treatment of pulmonary hypertension associated with bronchopulmonary dysplasia.     

Effect of booster blood transfusions on oxygen utilization in infants with bronchopulmonary dysplasia

To assess the impact of booster transfusions on oxygen utilization in infants with bronchopulmonary dysplasia, we noninvasively measured oxygen consumption (VO2) and the variables of systemic oxygen transport (SOT) before and 24 hours after transfusion therapy in 10 oxygen-dependent infants with bronchopulmonary dysplasia. The infants had been born with a mean gestational age of 27.6 weeks and a mean birth weight of 0.88 kg. Study weight averaged 1.24 +/- 0.35 kg, and study age averaged 5.5 +/- 2.4 weeks. Requirements for fractional concentration of inspired oxygen averaged 0.41 +/- 0.15 to maintain an oxygen saturation of 0.93 +/- 0.02. The VO2 was measured by means of a commercially available analyzer through a flow-through circuit and pump connected to a hood or in line with the ventilator. Cardiac output was calculated by means of pulsed Doppler ultrasonography. Oxygen saturation was measured by means of transcutaneous pulse oximetry. The coefficient of oxygen utilization was calculated as VO2/SOT. Transfusion consisted of packed erythrocytes (10 ml/kg). Oxygen utilization fell in all subjects after transfusion (p less than 0.01), but it fell more substantially in subjects with higher coefficients of oxygen utilization (r = -0.80, p less than 0.01), suggesting a physiologic benefit in selected patients, particularly those with higher levels of oxygen utilization. There was also a significant increase in overall systemic oxygen transport (p less than 0.01) and decrease in VO2 (p less than 0.02). Hemoglobin levels alone did not correlate with overall systemic oxygen transport, VO2, or level of oxygen use before transfusion, and thus did not predict which subjects would have a physiologic benefit from transfusion as reflected by falls in oxygen utilization.     

新生儿静息能量消耗测定研究

为探讨测定新生儿静息能量消耗(REE)的方法并对健康新生儿REE进行测定研究,本文应用间接能量测定仪对19例健康新生儿进行REE检测.结果表明健康新生儿REE为(189.2±27.4)kJ/kg,并与测定时体重、体表面积、预测值均呈显著相关关系,其中日龄和体表面积是REE主要决定因素.研究显示REE测定对新生儿营养支持有重要的临床应用价值.     

Comparison of arterial and transcutaneous oxygen partial pressure in infants with bronchopulmonary dysplasia

Transcutaneous PO2 (PTCO2) (Radiometer electrode heated to 44 degrees C) was compared to arterial PO2 (PaO2) in 19 infants with bronchopulmonary dysplasia: 12 infants were tested once, at the mean postnatal age of 14 weeks (range 4-43 weeks), the other 7 infants were studied longitudinally from 5 weeks (range 2-8 weeks) to 12 weeks (range 6-18 weeks) of postnatal age. The protocol was standardized: measurement during behavioral stage 1, using a peripheral arterial line. Twenty-eight comparisons between PTCO2 and PaO2 were obtained. PTCO2 was significantly related to PaO2 [PTCO2 (mmHg) = 0.81 PaO2 + 5.2, r = 0.73, p less than 0.01]. The mean difference PTCO2 - PaO2 was -7.2 mmHg (range: -34.5 to + 33); in the studied age range the PTCO2 - PaO2 was not significantly related to postnatal age (r = -0.24; p greater than 0.1).     

Home oxygen therapy in infants with bronchopulmonary dysplasia: a prospective study

We followed the clinical course of 21 infants with bronchopulmonary dysplasia enrolled in a prospective home O₂ therapy programme during a 4-year-period. Mean gestational age was 28.5 weeks (range, 25–36 weeks) and mean birth weight 1093 g (range 630–2750 g). Infants were regularly monitored to maintain pulse oximeter O₂ saturation over 94%–95%. The source of O₂ was liquid oxygen and was delivered by nasal cannula. During the follow up oxygenation was assessed by SatO₂ measurement, cardiac function by Doppler echocardiography and respiratory function by the occlusion technique. All patients had an ophthalmological follow up. The mean age of the infants at discharge was 3.7 months (range 1.7–8.6) and mean weight 2830 g (range 2150–3780 g). At discharge 8 infants had right ventricular hypertrophy (RVH) and four of them had pulmonary hypertension. Mean duration of home O₂ therapy was 97 days (range 15–320 days) and the mean age of discontinuation of O₂ was 6.9 months (range 3–14.7 months). The cardiological follow up was benign: the ECG signs of RVH disappeared by 12 months of age in six out of eight infants and the right ventricular pulmonary pressure, as measured by the Doppler method, normalised in the four patients in whom it was detected. No relationship was found between respiratory mechanics and the duration of O₂ therapy. Weight gain was poor with mean growth at the 3rd percentile for females and just below the 3rd percentile for males. Twelve of the 21 infants required 25 rehospitalizations. No one presented deterioration of retinopathy of prematurity that was present in 16 infants at discharge; at 12 months retinopathy was resolved in 14 infants. A total of 2025 hospital days were saved, representing a significant financial saving. Conclusion Home O₂ therapy permits the safe early discharge of O₂-dependent BPD infants and it reduces significantly the length of time spent in hospital which represents a considerable financial saving. Received: 17 December 1996 and in revised from: 15 April 1997 / Accepted: 29 April 1997     

Effects of furosemide on body water compartments in infants with bronchopulmonary dysplasia

We studied the effects of a single dose of intravenous furosemide on the body water compartments of nine infants with bronchopulmonary dysplasia. We measured total body water, extracellular water, and plasma volume using deuterium oxide, sodium bromide, and Evans blue dye, respectively. From the results of these measurements, we calculated cell water, interstitial water, red cell volume, and total blood volume. We performed these measurements on the first day of the study and again 28 h later, 4 h after an intravenous dose of furosemide (1 mg/kg). All infants had a brisk diuresis in the first hour after the dose, but urine output was no greater during the 24-h period after the dose than during the preceding 24-h period. Total body water, extracellular water, and interstitial water were significantly decreased 4 h after furosemide. There was no change in plasma volume, red cell volume, or total blood volume.     

Home oxygen therapy in infants with bronchopulmonary dysplasia: assessment of parental anxiety

BACKGROUND: It is conceivable that a complicated recovery course in a high-risk premature infant managed at home generates apprehension and anxiety in parents. AIMS: We attempted to define the evolution of anxiety levels in a population of parents of low-birth-weight premature infants with bronchopulmonary dysplasia enrolled in a prospective home O(2) therapy program. STUDY DESIGN: In the immediate pre-discharge [mean postnatal age 95 (45-158) days], a questionnaire (State-Trait Anxiety Inventory form Y) was given to all parents of the premature infants [mean birth weight 1106 (0.610-1.770) kg; mean gestational age 27.1 (24-31) weeks] present for the discharge. Subsequently, the parents were assessed twice, initially after a week from the discharge of their infants and then at the end of the oxygen therapy phase [mean postnatal age 185 (60-361) days]. They included 10 mothers and 10 fathers, aged 33.5+/-0.5 and 37+/-0.2 years, respectively. RESULTS: Our results indicate that these parents present an increased state anxiety level upon hospital discharge of their oxygen-dependent premature infants, which decreases as the improvement of respiratory status and the cessation of oxygen-dependency become evident [mean+/-S.D. related to age (T) maternal values 47.1+/-7.0, 41.8+/-5.6, 39.1+/-4.7, respectively; mean+/-S.D. related to age (T) paternal values 42.2+/-8.5, 41.1+/-8.1, 40.5+/-8.2, respectively]. When assessed separately by parental gender, in the maternal group, state anxiety decreased significantly (ANOVA, p<0.05). CONCLUSIONS: These data indicate that although neonatologists generally define the discharge of prematures with chronic lung disease based upon the acquired stabilization of vital parameters, in the oxygen-dependent group, they should also pay special attention to the emotional support of the parents who we have identified as being at increased risk for pre-discharge anxiety.     

Management of infants with bronchopulmonary dysplasia in Germany

Although official guidelines for diagnosis and treatment of bronchopulmonary dysplasia (BPD) exist in Germany the practice in tertiary care neonatology centres differs considerably. There is no consensus about the appropriate level of oxygen saturation for infants at risk for BPD or infants with established BPD. Targeting oxygen saturation just below 90% in the first weeks and in the lower nineties thereafter seems to be a reasonable approach. Systemic corticosteroids must be used very restrictively because of adverse short- and long-term outcomes. Diuretics, inhaled corticosteroids, and bronchodilators may be used based on a stringent assessment of the individual response; their routine use cannot be recommended. Domiciliary oxygen is a therapy rarely prescribed in Germany although, if carefully planned and organised, it is safe and effective. Infants with home oxygen need a close follow-up by neonatologists and other specialists. Routine vaccination is recommended from the postnatal age of 3 months onwards.