Indomethacin promotes germinal matrix microvessel maturation in the newborn beagle pup

Effects of prophylactic low-dose indomethacin on hemodynamics in very low birth weight infants

Indomethacin decreases cerebral and mesenteric blood flow velocities in premature infants with symptomatic patent ductus arteriosus. Low-dose indomethacin is recommended for the prevention of intraventricular hemorrhage in very low birth weight infants. The hemodynamic effects of prophylactic indomethacin have not been previously examined. We hypothesized that prophylactic indomethacin does not change cerebral and mesenteric blood flow velocities and cardiac function in very low birth weight infants. Twenty-one infants (775 to 1245 gm, 24 to 31 weeks' gestation) were studied before and after indomethacin (0.1 mg/kg) administration at 6, 30, and 54 hours of life. Mean and end-diastolic cerebral and mesenteric blood flow velocities decreased (ANOVA, p < 0.05) after prophylactic indomethacin. The 38% increase in cerebral relative vascular resistance was significantly greater than the 18% increase in mesenteric relative vascular resistance (ANOVA, p < 0.05). In five infants who were fed 1 hour after the third indomethacin dose, the postprandial mesenteric blood flow velocity was significantly greater than the mesenteric blood flow velocity before both indomethacin and feeding (ANOVA, p < 0.05). Cardiac output, stroke volume, fractional shortening, and blood pressure did not change after prophylactic indomethacin administration. We conclude that prophylactic indomethacin (1) reduces cerebral and mesenteric blood flow velocity without affecting cardiac function, (2) increases cerebral more than mesenteric relative vascular resistance, and (3) does not prevent postprandial increases in mesenteric blood flow velocity. We speculate that the increase in cerebral relative vascular resistance is a beneficial effect that contributes to protection against intraventricular hemorrhage.

Maternal intrauterine infection, cytokines, and brain damage in the preterm newborn

To evaluate the hypothesis that the proinflammatory cytokines IL-1, IL-6, and tumor necrosis factor-alpha might be the link between prenatal intrauterine infection (IUI) and neonatal brain damage, the authors review the relevant epidemiologic and cytokine literature. Maternal IUI appears to increase the risk of preterm delivery, which in turn is associated with an increased risk of intraventricular hemorrhage, neonatal white matter damage, and subsequent cerebral palsy. IL-1, IL-6, and TNF-alpha have been found associated with IUI, preterm birth, neonatal infections. and neonatal brain damage. Unifying models not only postulate the presence of cytokines in the three relevant maternal/fetal compartments (uterus, fetal circulation, and fetal brain) and the ability of the cytokines to cross boundaries (placenta and blood-brain barrier) between these compartments, but also postulate how proinflammatory cytokines might lead to IVH and neonatal white matter damage during prenatal maternal infection. Interrupting the proinflammatory cytokine cascade might prevent later disability in those born near the end of the second trimester.

Lack of effect of antenatal indomethacin on fetal cerebral blood flow

OBJECTIVE

Our purpose was to investigate fetal cerebral blood flow and the incidence of intraventricular hemorrhage in patients undergoing tocolysis with either indomethacin or magnesium sulfate at < 30 weeks' gestation.

STUDY DESIGN

Consenting patients at < 30 weeks' gestation with preterm labor were randomized to receive indomethacin or magnesium sulfate tocolysis. Magnesium sulfate was administered intravenously with an 8 gm loading dose given over the first hour, 4 gm over the second hour, and then a maintenance infusion of 2.5 gm per hour. The infusion was continued for approximately 12 hours after the cessation of uterine contractions. Patients randomized to receive indomethacin were given an initial dose of 50 to 100 mg orally or per rectum, followed by 25 to 50 mg orally every 4 to 6 hours for 24 to 48 hours. Oral tocolytic agents were not used after successful tocolysis. Betamethasone was administered to all patients. Patients underwent fetal cerebral Doppler studies during tocolytic therapy and at least 24 hours after completion of the treatment.

RESULTS

Twelve patients were randomized to receive indomethacin and twelve patients were randomized to receive magnesium sulfate. Twenty-one fetuses underwent cerebral Doppler studies in triplicate during and after therapy. The mean gestational age at tocolysis was 27.5 +/- 1.9 weeks for the indomethacin group and 26.4 +/- 1.6 weeks for the magnesium sulfate group (p = 0.14). The middle cerebral artery resistance index for fetuses during indomethacin treatment was 0.73 +/- 0.09, whereas the resistance index after therapy was 0.75 +/- 0.05 (p = 0.49). The resistance index during magnesium sulfate tocolysis was 0.79 +/- 0.04 and after therapy it was 0.76 +/- 0.04 (p = 0.18). There was no significant difference in the resistance index between the groups on or off therapy. In addition, the incidence of intraventricular hemorrhage was similar in both groups.

CONCLUSION

These results suggest that indomethacin does not significantly affect fetal cerebral blood flow. If antenatal indomethacin in the preterm fetus increases the risk of intraventricular hemorrhage, it would appear to be by another mechanism.

Effect of dual tocolysis on the incidence of severe intraventricular hemorrhage among extremely low-birth-weight infants

OBJECTIVE

Our purpose was to evaluate the null hypothesis that dual tocolysis with magnesium sulfate and indomethacin does not alter the rate of grade III or IV intraventricular hemorrhage.

STUDY DESIGN

Fifty-six neonates weighing 500 to 800 gm from mothers who received tocolytic therapy with magnesium sulfate alone or in combination with indomethacin were the subjects of this retrospective study. Demographic variables were evaluated with a Student t test, chi(2) analysis, Fisher exact test, or Mantel-Haenszel chi(2) as appropriate.

RESULTS

There was an increased incidence of grade III to IV intraventricular hemorrhage among patients treated with dual therapy (p = 0.02). Logistic regression showed that fetal age and dual tocolysis with indomethacin were the only independent prognostic factors for severe intraventricular hemorrhage.

CONCLUSION

The results indicate that dual tocolysis with indomethacin may place extremely low-birth-weight infants at increased risk for grade III to IV intraventricular hemorrhage.

Is surgical ligation of a patent ductus arteriosus the preferred initial approach for the neonate with extremely low birth weight?

The optimal approach to a patent ductus arteriosus (PDA) in an extremely low birth weight (ELBW) neonate, whether initial surgical ligation or a trial of indomethacin, has not been established. The authors reviewed the records of 82 ELBW premature infants who had surgical ligation of a PDA during a 2-year period. Thirty-one received indomethacin before ligation. Bronchopulmonary dysplasia (BPD) occurred in 33% of the infants. Predictors of BPD were prolonged positive pressure ventilation, severe intraventricular hemorrhage (IVH) and lower birth weight (BW). Seventy-seven percent of the infants survived. Predictors of mortality were severe IVH, lower BW, and the occurrence of necrotizing enterocolitis (NEC). The indomethacin-treated infants had a lower incidence of NEC and IVH. Overall, 16% of the patients had perioperative morbidity, and 10% of the patients died. The study shows that a trial of indomethacin therapy is not associated with increased complications in ELBW infants with PDA.

Prophylactic indomethacin: systematic review and meta-analysis

AIMS

To examine the effectiveness of prophylactic intravenous indomethacin in reducing the mortality and morbidity associated with patent ductus arteriosus and intraventricular haemorrhage in infants weighing less than 1750 g at birth.

METHODS

A literature search from 1980 onwards was made of three databases: Medline; Embase; and the Oxford Database of Perinatal Trials. Using strict criteria applied to randomised controlled trials only, two observers independently selected 14 studies for inclusion in the review. The methodological quality of each study was assessed independently by two observers using explicit criteria. Data on relevant outcome measures were extracted on two separate occasions. Where appropriate, the results of individual trials were combined using meta-analysis techniques to provide a pooled estimate of effect.

RESULTS

There is a trend towards reduced neonatal mortality in infants receiving prophylactic indomethacin, pooled estimate of risk difference -0.025 (95% confidence interval (CI) -0.061, 0.010). The incidence of symptomatic patent ductus arteriosus is significantly reduced in treated infants, pooled estimate of risk difference -0.217 (95% CI -0.275, -0.160), but there is no evidence that treatment affects respiratory outcomes. Prophylactic indomethacin significantly reduces the incidence of grades 3 and 4 intraventricular haemorrhage in treated infants, pooled estimate of risk difference -0.039 (95% CI -0.066, -0.011). However, there is no sound evidence assessing the long term effect of prophylaxis on neurodevelopmental outcome. Although there is a trend in treated infants towards an increased incidence of necrotising enterocolitis, pooled estimate of risk difference 0.015 (95% CI -0.002, 0.033), and some evidence that treatment may transiently impair renal function, there is no evidence that haemostasis is disturbed.

CONCLUSION

Prophylactic treatment with indomethacin has several immediate benefits. However, more data are needed on the incidence of possible adverse effects and neurodevelopmental outcomes before routine use of this therapy can be recommended.

Prevention of intraventricular hemorrhage in preterm infants

Prematurely born infants with intraventricular hemorrhage (IVH) suffer significant morbidity and mortality, particularly those infants with high grade hemorrhage. The more premature infants have a higher incidence, experiencing more severe IVH. Early onset IVH is also likely to be severe and to progress to a higher grade. The etiology of intraventricular hemorrhages is clearly multifactorial, with differing sets of risk factors for early onset and later occurring hemorrhage. Prevention requires multilayered strategies, both prenatal and postnatal. These strategies are discussed in detail, highlighting unresolved controversies. Certain recommendations for prevention can be made. These include efforts to prevent preterm delivery, transfer of high risk mothers to tertiary care centers and antenatal maternal steroid use. Postnatally, the importance of optimal resuscitation and neonatal care practices is stressed, particularly those which minimize cerebral blood flow fluctuation. Postnatal indomethacin use should be considered in most infants. Further investigation of other strategies is necessary, including multicenter randomized trials to further evaluate antenatal pharmacologic agents, as well as the relative efficacy of different modes of delivery. The different risk factors for early onset versus later onset IVH must be more clearly delineated. Most importantly, any strategy must include sustained neurodevelopmental followup.

Antenatal steroids, delivery mode, and intraventricular hemorrhage in preterm infants

OBJECTIVE

The relationship between antenatal steroids, delivery mode, and early-onset intraventricular hemorrhage was examined in very-low-birth-weight infants.

STUDY DESIGN

A total of 505 preterm infants (birth weight 600 to 1250 gm) were enrolled in a multicenter, prospectively randomized, controlled trial evaluating the efficacy of postnatal indomethacin to prevent intraventricular hemorrhage. All infants had echoencephalography between 5 and 11 hours of life.

RESULTS

Seventy-three infants had intraventricular hemorrhage within the first 5 to 11 hours (mean age at echoencephalography 7.5 hours). Four hundred thirty-two infants did not have early intraventricular hemorrhage. There was less antenatal steroid treatment (19% vs 32%, p = 0.03) and more vaginal deliveries (71% vs 45%, p < 0.0001) in the group with early intraventricular hemorrhage. Of 152 infants who received antenatal steroids, those delivered by cesarean section had significantly less early-onset intraventricular hemorrhage than did those delivered vaginally (4% vs 17%, p = 0.02). Of the 353 not exposed to antenatal steroids, 10% of infants delivered by cesarean section and 22% delivered vaginally had early intraventricular hemorrhage (p = 0.003).

CONCLUSION

These data are the first to suggest that both antenatal steroids and cesarean section delivery have an important and independent role in lowering the risk of early-onset intraventricular hemorrhage.

Low-dose indomethacin therapy and extension of intraventricular hemorrhage: a multicenter randomized trial

We enrolled 61 neonates of 600 to 1250 gm birth weight with evidence of low-grade intraventricular hemorrhage at 6 to 11 hours of age in a prospective, randomized, placebo-controlled trial to test the hypothesis that indomethacin (0.1 mg/kg given intravenously at 6 to 12 postnatal hours and every 24 hours for two more doses) would prevent extension of intraventricular hemorrhage. Twenty-seven infants were assigned to receive indomethacin; 34 infants received saline placebo. There were no significant differences between the two groups in birth weight, gestational age, sex, Apgar scores, percentage of infants treated with surfactant, or distribution of hemorrhages at the time of the first cranial sonogram (echo-encephalogram). Within the first 5 days, 9 of 27 indomethacin-treated and 12 of 34 saline solution-treated infants had extension of their initial intraventricular hemorrhage (p = 1.00). Four indomethacin-treated and three saline solution-treated infants had parenchymal extension of the hemorrhage. Indomethacin was associated with closure of a patent ductus arteriosus by the fifth day of life (p = 0.003). There were no differences in adverse events attributed to indomethacin. We conclude that in very low birth weight infants with low grade intraventricular hemorrhage within the first 6 postnatal hours, prophylactic indomethacin therapy promotes closure of the patent ductus arteriosus and is not associated with adverse events, but does not affect the cascade of events leading to parenchymal involvement of intracranial hemorrhage.

Extracellular matrix-degrading proteinases in the nervous system

The proteolytic activities of matrix metalloproteinases and plasminogen activators as well as their inhibitors are important in maintaining the integrity of the extracellular matrix (ECM). Cell-ECM interactions influence cell proliferation, differentiation, adhesion and migration. In the nervous system, proteolysis of the ECM is involved in neuronal cell migration in the developing cerebellum and in neurite outgrowth. Likewise, in pathological conditions such as brain tumour growth and invasion, leukocyte infiltration into brain tumours, leukocyte trafficking in the central nervous system in inflammatory diseases such as multiple sclerosis and viral encephalitis, and in nerve demyelination, matrix-degrading proteinases and their inhibitors have been implicated. An understanding of cell-ECM interactions and ECM degradation in diseases of the nervous system would provide new insight for drug design and other forms of therapy.