Dexamethasone therapy for bronchopulmonary dysplasia: improved respiratory mechanics without adrenal suppression

Follow-up of a randomized, placebo-controlled trial of dexamethasone to decrease the duration of ventilator dependency in very low birth weight infants: neurodevelopmental outcomes at 4 to 11 years of age

OBJECTIVE

High doses of dexamethasone reduce the risk of chronic lung disease among premature infants but may increase the risk of developmental impairments. The objective of this study was to compare developmental outcomes beyond infancy for children who, as neonates, participated in a randomized trial of dexamethasone.

PATIENTS AND METHODS

One hundred eighteen children with birth weights <1500 g were randomly assigned at 15 to 25 days of life to a 42-day tapering course of dexamethasone or placebo. All 95 survivors were assessed by using standardized measures of developmental outcome at least once at or beyond 1 year of age, and 84 were examined at 4 to 11 years. For this follow-up study, the outcome of primary interest was death or major neurodevelopmental impairment, which was defined as cerebral palsy, cognitive impairment, or blindness.

RESULTS

On the basis of each child's most recent follow-up, the rates of major neurodevelopmental impairments were 40% for the dexamethasone group and 20% for the placebo group. The higher impairment rate for the dexamethasone group was mainly attributed to a higher prevalence of cerebral palsy. Rates of the composite outcome of death or major neurodevelopmental impairment were 47% and 41%, respectively.

CONCLUSION

A 42-day tapering course of dexamethasone, which was shown previously to decrease the risk of chronic lung disease in very low birth weight infants, does not increase the risk of the composite outcome of death or major neurodevelopmental impairment.

The effects of early postnatal dexamethasone therapy on pulmonary outcome in premature infants with respiratory distress syndrome: a two-year follow-up study

AIM

To evaluate the pulmonary outcome at corrected age of 2 y on preterm infants who participated in a double-blind trial of early postnatal dexamethasone therapy (< 12 h after birth) for the prevention of chronic lung disease.

METHODS

Clinical respiratory status, blood gases, acid-base balance and pulmonary function were evaluated at corrected age of 2 y in 116 preterm infants (59 infants in the control group; 57 in the dexamethasone-treated group). In the dexamethasone-treated group, dexamethasone was administered intravenously every 12 h in tapering doses: 0.25 mg/kg on days 1 through 7, 0.12 mg/kg on days 8 through 14, 0.05 mg/kg on days 15 through 21, and 0.02 mg/kg on days 21 through 28.

RESULTS

The clinical and laboratory characteristics in the perinatal period were comparable between the groups. At the time of follow-up (mean +/- SD corrected age was 25.1 +/- 4.8 mo for the control group and 24.6 +/- 5.1 mo for the dexamethasone-treated group), there was a slightly lower mean body weight and body length, and a lower psychomotor developmental index in the dexamethasone-treated group than in the control group (10.9 +/- 2.1 vs 11.5 +/- 1.9 kg, 84.4 +/- 6.1 vs 85.9 +/- 5.8 cm, and 82 +/- 24 vs 89 +/- 26, respectively); however, these differences were not statistically significant. There were no significant differences between the control and dexamethasone-treated groups in clinical respiratory status, blood gases, acid-base balance or in lung mechanics (V(T): 9.5 +/- 2.0 vs 9.4 +/- 1.9 ml/kg; V(min): 0.23 +/- 0.04 vs 0.23 +/- 0.03 l/min/kg; C(RS): 13.1 +/- 3.9 vs 12.6 +/- 3.6 ml/kPa/kg; R(RS): 1.56 +/- 0.64 vs 1.62 +/- 0.58 kPa/l/s, respectively).

CONCLUSION

There was no apparent adverse respiratory outcome associated with early postnatal dexamethasone therapy.

Effect of dexamethasone therapy on pulmonary function in chronic lung disease: a comparison of disease types

BACKGROUND

In the present study, we investigated the effect of dexamethasone (DEX) therapy on extubation and pulmonary function in patients with chronic lung disease (CLD) who required long-term mechanical ventilation. In addition, we compared the effects of DEX therapy among CLD types.

METHODS

Twenty-two CLD patients who were ventilator dependent for 28 days or longer received DEX therapy for the purposes of extubation. A tapering dose of DEX, starting from 0.5 mg/kg per day, was administered for 7 days. Pulmonary function was measured at initiation of administration and 4 days after initiation. We evaluated static respiratory system compliance (Crs) and static respiratory system resistance (Rrs) adjusted by bodyweight. Chronic lung disease types were categorized according to the classification of the Ministry of Health and Welfare Research Project. We compared the effect of DEX therapy among CLD types.

RESULTS

Dexamethasone therapy was started at a mean (+/-SD) 45 =/- 11 days after birth and 32.1 +/- 1.3 weeks of postconceptional age in infants with a mean bodyweight of 939 +/- 153 g. After DEX therapy, extubation was successful in all 22 patients. Following DEX administration, Crs was significantly increased from 0.69 +/- 0.13 to 1.17 +/- 0.21 mL/cm H2O per kg. In contrast, Rrs did not show any clear changes. Comparing CLD types, no difference was observed for Crs and Rrs in each disease type.

CONCLUSIONS

Dexamethasone was administered to CLD patients requiring long-term mechanical ventilation for the purposes of extubation and extubation was successful in all patients. It was found that Crs was increased in all patients following DEX, regardless of CLD type. The increase in Crs following DEX administration may have been related to successful extubation.

Use of corticosteroids and the outcome of infants with bronchopulmonary dysplasia

Ventilator-dependent premature infants are often treated with dexamethasone. Several trials showed that steroids while improve pulmonary compliance and facilitate extubation, some treated infants may have adverse effects, such as alterations of growth curves. We conducted this retrospective study to evaluate the effects of steroids on mechanical ventilation, oxygen therapy, hospital length stay and mortality, in ventilator-dependent infants with bronchopulmonary dysplasia (BPD) (defined as the need of oxygen supplementation at 28 days of life). Twenty-six newborns with BPD were evaluated during 9 - 42 days postpartum (mean = 31 days) and were divided into two groups: Group I - 14 newborns that did not receive dexamethasone, and Group II - 12 newborns that received dexamethasone at 14 - 21 days of life. Dexamethasone was given at a dose of 0.25 mg per kilogram of body weight twice daily intravenously for 3 days, after which the dose was tapered.

RESULTS

There were no statistically significant differences in the mean length of mechanical ventilation (Group I - 37 days, Group II - 35 days); oxygen supplementation (Group I - 16 days, Group II - 29 days); hospital stay (Group I - 72 days, Group II - 113 days); mortality (Group I - 35.7%, Group II - 41.6%). At birth, Group II was lighter (BW: Group I - 1154 grams +/- 302, Group II - 791 grams +/- 165; p < 0.05) and smaller (height: Group I - 37.22 cm +/- 3.3, Group II - 33.5 +/- 2.4; p< 0.05) than Group I. At 40 weeks, there were no statistically significant differences between groups in relation to anthropometric measurements.

CONCLUSIONS

The use of corticosteroids in bronchopulmonary dysplasic infants may influence the somatic growth during its use. However, after its suspension, a recovery seems to occur, suggesting that its influence could be transitory.

Dexamethasone therapy in chronic lung disease

Steroids have been used in the treatment of infants with chronic lung disease (CLD) for over a decade. Some studies have reported beneficial effects from long, tapering 42-day course of dexamethasone. Short term regimens have also shown beneficial effects on ventilator dependent infants with CLD. Although steroid therapy has been successful in infants with established CLD, more recently, dexamethasone therapy is being initiated in infants with RDS considered to be at risk for developing CLD. Some of the initial studies reported higher rates of infection, but more recent prospective data have not shown an increased incidence of sepsis in patients treated with steroids. Presently, early steroid therapy appears to be beneficial to minimize lung injury in infants treated with surfactant.

[Physiological basis for the use of muscarine antagonists in bronchopulmonary dysplasia]

The rationale for the use of muscarinic antagonists in bronchopulmonary dysplasia (BPD) is based on the physiology and pharmacology of airway smooth muscle, the pathology of BPD, and the response of infants with BPD to bronchodilators, in vivo and in vitro studies of airway smooth muscle of newborn animals and humans indicate that vagal efferent airway innervation and/or muscarinic receptors are functional at birth, as well as early in gestation. Current concepts regarding muscarinic receptor subtypes suggest that M3 receptors mediate airway smooth muscle contraction, M2 receptors are autoinhibitory and limit vagally-mediated bronchoconstriction, and M1 receptors may play a facilitatory role in ganglionic transmission. Muscarinic receptor subtypes appear to be functionally expressed at birth but may undergo developmental regulation. Infants with BPD have an elevated pulmonary resistance that is accompanied by hypertrophy of airway smooth muscle, b2-agonists cause bronchodilation in BPD as does atropine in infants recovering from severe BPD. The synthetic congener of atropine, ipratropium bromide (IPB) causes bronchodilation in ventilator-dependent infants with BPD in a dose-dependent fashion. Nebulized IPB causes a decrease in respiratory resistance that reaches a maximum of 20% at 175 mg. The bronchodilation seen with muscarinic antagonists suggests that part of the elevated resistance associated with BPD is due to increased muscarinic tone, presumably vagal in origin. When IPB is combined with salbutamol (0.04 mg) the response is increased in magnitude and duration; reaching a slightly larger decreases in resistance (26%) that is now accompanied by an increase in compliance (20%).(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic lung disease of prematurity: are we too cautious with steroids?

Encompassed by the term chronic lung disease (CLD) of prematurity is a sequence of pathophysiological processes ranging from acute inflammation and its resolution to remodelling and growth. There is good evidence for clinical and biological effects of parenteral corticosteroid therapy at each stage in the disease process. A number of questions remain to be resolved: can risk prediction be refined to permit trials of prevention; what is the minimum effective dosage regime; are topical corticosteroids effective; what are the long-term effects on lung growth and development and indeed, is the long-term prognosis of CLD affected by corticosteroid therapy? It is prudent to be cautious with steroids until these questions are answered.