Effect of indomethacin on superior mesenteric artery blood flow velocity in preterm infants

Impact of maternal factors, environmental factors, and race on necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a complex disease with a multifactorial etiology. As the leading cause of intestinal morbidity and mortality among premature infants, many resources are being dedicated to neonatal care and molecular targets in the newborn intestine. However, NEC is heavily influenced by maternal and perinatal factors as well. Given its nature, preventive approaches to NEC are more likely to improve outcomes than new treatment strategies. Therefore, this review focuses on maternal, environmental, and racial factors associated with the development of NEC, with an emphasis on those that may be modifiable to decrease the incidence of the disease.

Relationship of patent ductus arteriosus management with neonatal AKI

OBJECTIVE

Investigate relationship between management of patent ductus arteriosus (PDA) and acute kidney injury (AKI) in very low birthweight neonates.

STUDY DESIGN

Retrospective cohort study of neonates, <1500 g, admitted to 24 NICUs, 1/1/14 - 3/31/14. AKI diagnosed using the neonatal modified KDIGO definition; diagnosis and treatment of PDA extracted from the medical record. Demographics, clinical characteristics, and AKI stage compared using chi-square and analysis of variance. A general estimating equation logistic regression used to estimate adjusted odds ratios.

RESULTS

Of 526 neonates with sufficient data to diagnose AKI, 157 (30%) had PDA (61 conservative management, 62 pharmacologic treatment only, 34 surgical ligation). In analyses adjusted for sex, birthweight, gestational age, caffeine, nephrotoxin exposure, vasopressor and mechanical ventilation use, with conservative management as reference, there were no differences among treatment cohorts in the odds of AKI.

CONCLUSION

The underlying physiology of PDA, not management strategy, may determine the likelihood of AKI in neonates <1500 g.

Management of Patent Ductus Arteriosus in Premature Infants in 2020

The patent ductus arteriosus (PDA) is the most commonly found cardiac condition in neonates. While there have been several studies and thousands of publications on the topic, the decision to treat the PDA is still strongly debated among cardiologists, surgeons, and neonatologists. This is in part due to the shortage of long-term benefits with the interventions studied. Practice variations still exist within sub-specialties and centers. This article briefly summarizes the history, embryology and histology of the PDA. It also succinctly discusses the hemodynamic significance of a PDA which builds the framework to review all the available literature on PDA closure in premature infants, though not a paradigm shift just yet; it introduces transcatheter PDA closure (TCPC) as a possible armament to the clinician for this age-old problem.

Management strategies for the preemie ductus

PURPOSE OF REVIEW

Patent ductus arteriosus (PDA) remains the most common cardiovascular condition afflicting neonates. Despite 5 decades of scientific inquiry pediatric cardiologists and neonatologists still cannot answer the simple question of which PDAs should be treated.

RECENT FINDINGS

Although the volume of the shunt is difficult to calculate, echocardiography, biochemical markers, and clinical exam can provide clues to the magnitude and physiologic consequences of the shunt. Epidemiologic data exists showing a positive relationship between a PDA and numerous morbidities. As a result, for most of the 20th and early 21st century, nearly all PDAs where indiscriminately considered to be hemodynamically significant and attempts to close it where initiated shortly after birth. However, no randomized trials of PDA closure have been able to show significant differences between affected and unaffected groups. In fact, surgical ligation has repeatedly been associated with increased morbidities and worse long-term neurodevelopmental outcomes. As a result, most clinicians favor a strategy of watchful waiting.

SUMMARY

In this review, we aim to summarize the scientific literature, along with some of the contemporary biases, that exist with regards to the pathophysiology, genetics, and treatment strategies for the neonatal PDA.

Impact of Continuous vs Bolus Feeding on Splanchnic Perfusion in Very Low Birth Weight Infants: A Randomized Trial

OBJECTIVE

To detect changes in splanchnic perfusion and oxygenation induced by 2 different feeding regimens in infants with intrauterine growth restriction (IUGR) and those without IUGR.

STUDY DESIGN

This was a randomized trial in 40 very low birth weight infants. When an enteral intake of 100 mL/kg/day was achieved, patients with IUGR and those without IUGR were randomized into 2 groups. Group A (n = 20) received a feed by bolus (in 10 minutes), then, after at least 3 hours, received the same amount of formula by continuous nutrition over 3 hours. Group B (n = 20) received a feed administered continuously over 3 hours, followed by a bolus administration (in 10 minutes) of the same amount of formula after at least 3 hours. On the day of randomization, intestinal and cerebral regional oximetry was measured via near-infrared spectroscopy and Doppler ultrasound (US) of the superior mesenteric artery was performed. Examinations were performed before the feed and at 30 minutes after the feed by bolus and before the feed, at 30 minutes after the start of the feed, and at 30 minutes after the end of the feed for the 3-hour continuous feed.

RESULTS

Superior mesenteric artery Doppler US showed significantly higher perfusion values after the bolus feeds than after the continuous feeds. Near-infrared spectroscopy values remained stable before and after feeds. Infants with IUGR and those without IUGR showed the same perfusion and oxygenation patterns.

CONCLUSION

According to our Doppler US results, bolus feeding is more effective than continuous feeding in increasing splanchnic perfusion.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01341236.

What is new for patent ductus arteriosus management in premature infants in 2015?

PURPOSE OF REVIEW

A patent ductus arteriosus (PDA) in premature infants is common and is associated with a number of adverse outcomes. The purpose of this review is to discuss recent literature in PDA diagnosis and management.

RECENT FINDINGS

The diagnosis of a 'hemodynamically significant' PDA is challenging and a robust definition is lacking. The risks and benefits of therapies, either medical or surgical, designed to close the PDA, are controversial. Oral acetaminophen has gained increasing attention as an alternative pharmaceutical agent for PDA closure in premature infants, although safety concerns remain. Compared to surgical ligation, transcatheter PDA closure may be associated with less risk and fewer adverse events. Both aggressive and conservative management of PDA has similar clinically important outcomes, although the strength of evidence is derived mostly from cohort studies.

SUMMARY

Clinicians should weigh the potential adverse effects of pharmaceutical or surgical PDA closure against the likelihood of spontaneous closure. The infant population most likely to benefit from PDA closure remains ill-defined and clinical context is recommended.

Evaluation of caffeine and the development of necrotizing enterocolitis

OBJECTIVE

To test the association between medical or surgical necrotizing enterocolitis (NEC) and caffeine administration in premature infants.

STUDY DESIGN

This single-center, retrospective study evaluated patients admitted to a level 3 neonatal intensive care unit (NICU) over an 18-month period. All patients were evaluated for factors associated with the development of NEC including exposure to caffeine (dosing and duration), gestational age, birth weight, vasoactive medications and maternal illicit drug use.

RESULTS

There were 615 subjects included in the study; among these subjects, 7.3% (n = 45) developed NEC (35 subjects receiving caffeine and 10 subjects not receiving caffeine). The administration of caffeine (p = 0.008), birth weight (p = 0.014) and the use of vasopressors (p = 0.033) were associated with the development of NEC. When considering only infants with a birth weight less than 1500 g and less than 32 weeks gestation, the effects of caffeine and vasopressor use remained statistically significant (p = 0.047 and p = 0.045, respectively). The time to development of NEC did not differ statistically between patients receiving caffeine and those not receiving caffeine (p = 0.129).

CONCLUSION

A potential association between the administration of caffeine and the development of medical or surgical necrotizing enterocolitis in premature infants exists. Further investigation of dose-dependent effects and loading doses is warranted.

Cyclooxygenase inhibitors in preterm infants with patent ductus arteriosus: effects on cardiac and vascular indices

Existing data suggest subendocardial ischemia in preterm infants with patent ductus arteriosus (PDA) and alterations in cardiac function after indomethacin administration. This study aimed to explore the evolution of left ventricular function by conventional echocardiography and speckle-tracking echocardiography (STE) and to ascertain the interrelationship with coronary flow indices in response to indomethacin. A prospective observational study was performed with preterm infants receiving indomethacin for medical closure of PDA. Serial echocardiography was performed, and the results were analyzed using analysis of variance. Intra- and interobserver variability was assessed using the intraclass correlation coefficient. Indomethacin was administered to 18 infants born at a median gestational age of 25.8 weeks (interquartile range [IQR], 24.2-28.1 weeks) with a birth weight of 773 g (IQR, 704-1,002 g). The median age of the infants was 7.5 days (IQR, 4-17). Global longitudinal strain (GLS) values significantly decreased immediately after indomethacin infusion (preindomethacin GLS, -19.1 ± 2.4 % vs. -15.9 ± 1.7 %; p < 0.0001) but had improved at reassessment after 1 h (-17.4 ± 1.8 %). Conventional echocardiographic indices did not show significant alterations. A significant increase in arterial resistance in the coronary vasculature from 1.7 to 2.4 mmHg/cm/s was demonstrated. A significant correlation was noted between peak systolic GLS and flow resistance in the coronary vasculature. Significant changes in myocardial indices were observed immediately after indomethacin infusion. Compared with conventional methods, STE is a more sensitive tool to facilitate understanding of hemodynamics in preterm infants.

Superior mesenteric artery blood flow velocities following medical treatment of a patent ductus arteriosus

We examined superior mesenteric artery blood flow velocity in response to feeding in infants randomized to trophic feeds (n = 16) or nil per os (n = 18) during previous treatment for patent ductus arteriosus. Blood flow velocity increased earlier in the fed infants, but was similar in the 2 groups at 30 minutes after feeding.

Patent ductus arteriosus in preterm infants: do we have the right answers?

Patent ductus arteriosus (PDA) is a common clinical condition in preterm infants. Preterm newborns with PDA are at greater risk for several morbidities, including higher rates of bronchopulmonary dysplasia (BPD), decreased perfusion of vital organs, and mortality. Therefore, cyclooxygenase (COX) inhibitors and surgical interventions for ligation of PDA are widely used. However, these interventions were reported to be associated with side effects. In the absence of clear restricted rules for application of these interventions, different strategies are adopted by neonatologists. Three different approaches have been investigated including prophylactic treatment shortly after birth irrespective of the state of PDA, presymptomatic treatment using echocardiography at variable postnatal ages to select infants for treatment prior to the duct becoming clinically significant, and symptomatic treatment once PDA becomes clinically apparent or hemodynamically significant. Future appropriately designed randomized controlled trials (RCTs) to refine selection of patients for medical and surgical treatments should be conducted. Waiting for new evidence, it seems wise to employ available clinical and echocardiographic parameters of a hemodynamically significant (HS) PDA to select patients who are candidates for medical treatment. Surgical ligation of PDA could be used as a back-up tool for those patients who failed medical treatment and continued to have hemodynamic compromise.

Management of patent ductus arteriosus in preterm infants--where do we stand?

Patent ductus arteriosus (PDA) in preterm infants is a controversial topic in the management of preterm neonates. There are no generally accepted guidelines for diagnosis, treatment, and follow-up of PDA, and few publications have covered the whole topic or have been conclusively summarized to give a proper direction for the treating physician. Major issues remain to be clarified, both with respect to diagnosis and treatment. The definition of hemodynamic significance varies because of different use of echocardiographic criteria and uncertainty about the role of biomarkers. The detailed risks and benefits of available treatment alternatives are still under investigation. There has been a general shift in the management of PDA in preterm neonates from the "aggressive approach" to a more "conservative approach," but the effects of this strategy on morbidity in a longer time perspective are not fully known. An individualized therapeutic strategy with special emphasis on identification of hemodynamically significance seems to be the way forward. In this review we put forward the scientific background in favor of a seemingly growing body of evidence against active treatment, but we raise caution against shying away from all forms of treatment or instituting them too late. Finally, we try to integrate the current knowledge into suggestions for the management of PDA in premature infants.

Enteral feeding during indomethacin and ibuprofen treatment of a patent ductus arteriosus

OBJECTIVE

To test the hypothesis that infants who are just being introduced to enteral feedings will advance to full enteral nutrition at a faster rate if they receive "trophic" (15 mL/kg/d) enteral feedings while receiving indomethacin or ibuprofen treatment for patent ductus arteriosus.

STUDY DESIGN

Infants were eligible for the study if they were 23(1/7)-30(6/7) weeks' gestation, weighed 401-1250 g at birth, received maximum enteral volumes ≤60 mL/kg/d, and were about to be treated with indomethacin or ibuprofen. A standardized "feeding advance regimen" and guidelines for managing feeding intolerance were followed at each site (N = 13).

RESULTS

Infants (N = 177, 26.3 ± 1.9 weeks' mean ± SD gestation) were randomized at 6.5 ± 3.9 days to receive "trophic" feeds ("feeding" group, n = 81: indomethacin 80%, ibuprofen 20%) or no feeds ("fasting [nil per os]" group, n = 96: indomethacin 75%, ibuprofen 25%) during the drug administration period. Maximum daily enteral volumes before study entry were 14 ± 15 mL/kg/d. After drug treatment, infants randomized to the "feeding" arm required fewer days to reach the study's feeding volume end point (120 mL/kg/d). Although the enteral feeding end point was reached at an earlier postnatal age, the age at which central venous lines were removed did not differ between the 2 groups. There were no differences between the 2 groups in the incidence of infection, necrotizing enterocolitis, spontaneous intestinal perforation, or other neonatal morbidities.

CONCLUSION

Infants required less time to reach the feeding volume end point if they were given "trophic" enteral feedings when they received indomethacin or ibuprofen treatments.

Feeding interval and postprandial intestinal blood flow in premature infants

BACKGROUND

The feeding interval is an important factor in enteral feeding of premature infants. We investigated postprandial intestinal blood flow in stable very-low-birthweight infants fed at 2-h and 3-h intervals.

METHODS

We used pulsed wave Doppler ultrasound to measure blood flow velocity of the superior mesenteric artery (SMA) before feeding and at 15, 30, 45, and 60 min after feeding. Measurements were made on the day of starting enteral nutrition (1 or 2 days of age), and at 3 and 5 days of age. A total of 21 studies were performed in seven infants fed every 2 h, and 54 studies were performed in 18 infants fed every 3 h.

RESULTS

In infants fed every 2 h, SMA blood flow velocity increased from before feeding to 30 min after feeding and then decreased at 60 min after feeding. In infants fed every 3 h, SMA blood flow velocity increased after feeding, reaching a peak at 30 min. The correlation coefficients between the volume of milk per feed and the postprandial increase in time-averaged mean blood flow velocity were 0.398 (P = 0.074, n = 21) and 0.597 (P = 0.000, n = 54) in infants fed at 2-h and 3-h intervals, respectively.

CONCLUSIONS

SMA blood flow velocity significantly increased after feeding in infants fed at 2-h and 3-h intervals. The volume of milk per feed might affect the postprandial increase in SMA blood flow velocity.

Effects of prophylactic indomethacin on renal and intestinal blood flows in premature infants

BACKGROUND

Prophylactic indomethacin reduces severe intraventricular hemorrhage and symptomatic patent ductus arteriosus in premature infants. The purpose of this study was to investigate the effects of prophylactic low-dose indomethacin on renal and intestinal blood flow.

METHODS

Subjects were 19 extremely low-birthweight infants admitted to our hospital and enrolled in a multicenter randomized control trial to study the efficacy and complications of prophylactic low-dose indomethacin in the reduction of severe intraventricular hemorrhage and patent ductus arteriosus (indomethacin and placebo groups, ten and nine infants, respectively). We measured blood flow velocity in the right renal artery (right RA) and superior mesenteric artery (SMA) with pulsed Doppler ultrasound before and after the administration of the first dose of 0.1 mg/kg indomethacin or placebo.

RESULTS

End-diastolic blood flow velocity (EDV) in the right RA and SMA increased significantly after the administration of indomethacin (P = 0.0414 and 0.0284, respectively), although the time-averaged mean blood flow velocity (TAV) did not change significantly in either artery. In the placebo group, the pre- and postadministration values for TAV and EDV in the right RA and SMA did not differ. Neither group showed a significant change in the relative vascular resistance (mean blood pressure/TAV) in the right RA or SMA. EDV in the left pulmonary artery was significantly reduced only after the administration of indomethacin (P = 0.0284).

CONCLUSIONS

Prophylactic low-dose indomethacin increases the diastolic blood flow in the RA and SMA via a reduction in the ductal shunt volume, with no change in the regional vascular resistance.

Patent ductus arteriosus: are current neonatal treatment options better or worse than no treatment at all?

Although a moderate-sized patent ductus arteriosus (PDA) needs to be closed by the time a child is 1-2 years old, there is great uncertainty about whether it needs to be closed during the neonatal period. Although 95% of neonatologists believe that a moderate-sized PDA should be closed if it persists in infants (born before 28 weeks) who still require mechanical ventilation, the number of neonatologists who treat a PDA when it occurs in infants who do not require mechanical ventilation varies widely. Both the high likelihood of spontaneous ductus closure and the absence of randomized controlled trials, specifically addressing the risks and benefits of neonatal ductus closure, add to the current uncertainty. New information suggests that early pharmacologic treatment has several important short-term benefits for the preterm newborn. By contrast, ductus ligation, while eliminating the detrimental effects of a PDA on lung development, may create its own set of morbidities that counteract many of the benefits derived from ductus closure.

Evidence-based use of indomethacin and ibuprofen in the neonatal intensive care unit

Indomethacin and ibuprofen are potent inhibitors of prostaglandin synthesis. Neonates have been exposed to these compounds for more than 3 decades. Indomethacin is commonly used to prevent intraventricular hemorrhage (IVH), and both drugs are prescribed for the treatment or prevention of patent ductus arteriosus (PDA). This review examines the basis for indomethacin and ibuprofen use in the neonatal intensive care population. Despite the call for restrained use of each drug, the most immature infants are likely to need pharmacologic approaches to reduce high-grade IVH, avoid the need for PDA ligation, and preserve the opportunity for an optimal outcome.

Indomethacin impairs coronary perfusion in infants with hemodynamically significant ductus arteriosus

BACKGROUND

A haemodynamically significant ductus arteriosus (HSDA) is commonly associated with morbidity in preterm infants.

AIM

To study the effect of the first dose of indomethacin on coronary blood flow in preterm neonates diagnosed with an HSDA.

METHOD

A prospective observational echocardiographic study was performed on preterm infants. A single study dose of intravenous indomethacin (0.1 mg/kg) was administered over 1 h. Serial echocardiography was performed before and after indomethacin treatment to study the effect on coronary artery perfusion and cardiovascular performance.

RESULTS

Eighteen infants born at a median gestation of 25.8 (24.2, 28.1) weeks and a birth weight of 773 g (704, 1,002) were evaluated. The median age at indomethacin administration was 7.5 days (4, 17). There was no significant change in arterial pressure or ventilatory indices. Left anterior descending artery diastolic velocity and time integral declined from 0.3 ± 0.1 and 3.19 ± 1.2 m/s to 0.22 ± 0.08 and 2.01 ± 0.9 m/s, respectively, within 10 min of completion of infusion. These indices showed partial recovery when reassessed after 60 min. There were no changes in left ventricular output or transductal flow.

CONCLUSIONS

Intravenous indomethacin was followed by a decline in coronary arterial diastolic blood flow.

Current evidence on the safety profile of NSAIDs for the treatment of PDA

Patent ductus arteriosus (PDA) complicates the clinical course of preterm infants. Nonsteroidal anti-inflammatory drugs, especially Indomethacin and Ibuprofen, have been widely used for both prevention and treatment of PDA. Short-term efficacy of Indomethacin or Ibuprofen is equivalent, while Ibuprofen results show a higher safety profile. Ibuprofen is associated with fewer clinical gastrointestinal and renal side effects with respect to Indomethacin even if subclinical potential effects are reported. When administered as prophylaxis, Ibuprofen has no effects on prevention of intraventricular haemorrhage unlike Indomethacin. Considering the potential adverse effects of both these drugs, a careful monitoring during and after the treatment period is highly recommended.

Variation in the diagnosis and management of patent ductus arteriosus in premature infants

OBJECTIVES

To determine variations in neonatology practice regarding the diagnosis and management of patent ductus arteriosus (PDA) in premature infants.

DESIGN

Standardized telephone interview of preferences and practices.

SUBJECTS

Canadian neonatologists in active clinical practice.

RESULTS

Of 136 eligible Canadian neonatologists, 100 respondents (74%) estimated the proportion of infants with suspected PDA who have echocardiography to be a median of 80% (range 0% to 100%), with considerable variation both within and between centres. Only two centres had written guidelines. More recent medical school graduates were significantly more likely to use echocardiography. Increased use of echocardiography was also significantly related to increased availability. Fluid restriction and indomethacin was used as initial therapy by 89% of respondents, with the indomethacin dose standardized for 83%; surgical ligation was used when indomethacin therapy was contraindicated or had failed. Personal guidelines directed decisions regarding therapy for the majority of neonatologists.

CONCLUSIONS

Among Canadian neonatologists, there is considerable variation regarding practices related to the diagnosis and management of PDA in premature infants. This variation may potentially affect the cost effectiveness of care for these patients.

Doppler manifestations of ductal steal: role in decision making

Patent ductus arteriosus in extremely premature babies is associated with major neonatal morbidities such as necrotizing enterocolitis and intraventricular haemorrhage. Altered systemic blood flow and end-organ hypoperfusion are known associates of a haemodynamically significant ductus arteriosus where descending aorta blood flow profiles may reveal abnormal diastolic retrograde flow. A preterm neonate was noted to have a large symptomatic patent ductus arteriosus with reversal of diastolic flow in the superior mesenteric vessels. Treatment with indomethacin led to ductal closure and concomitant restoration of diastolic flow and resolution of symptoms. Doppler studies of systemic vessels may help improve our understanding of the systemic impact of a haemodynamically significant ductus arteriosus.

Spectral Doppler waveforms in systemic arteries and physiological significance of a patent ductus arteriosus

Patent ductus arteriosus in extremely premature babies is associated with major neonatal morbidities, such as necrotizing enterocolitis and intraventricular hemorrhage. This may be attributable, at least in part, to systemic hypoperfusion secondary to ductal steal. A hemodynamically significant ductus arteriosus (HSDA) is known to be associated with altered systemic blood flow and end-organ hypoperfusion. Although descending aorta blood flow profiles may show abnormal diastolic retrograde flow, Doppler studies of blood flow in the systemic arteries may help improve our understanding of the relationship of a HSDA with these morbidities. In this article, we discuss aspects of diastolic blood flow reversal in the systemic arteries in premature infants with a hemodynamically significant duct. Whether these hemodynamic effects are significant enough to form the basis for initiating treatment is still unclear; these should form the basis for prospective studies.

Hemodynamic alterations associated with polycythemia and partial exchange transfusion

Polycythemia hyperviscosity syndrome has been associated with multiple systemic effects. There is dearth of data on the effects of polycythemia on cardiac function. This case presents a newborn infant with symptomatic polycythemia in whom detailed myocardial function analysis for systolic and diastolic performance, as well as end-organ perfusion assessment was carried out using transthoracic echocardiography. Hemodynamic information in polycythemic infants before and after partial exchange could improve our understanding of the impact on myocardial performance.

Prophylactic indomethacin in extremely premature infants between 23 and 24 weeks gestation

BACKGROUND

In extremely premature infants, the presence of a left-to-right shunt through a patent ductus arteriosus (PDA) increases the risks of pulmonary hemorrhage, intraventricular hemorrhage, necrotizing enterocolitis, renal failure, and chronic lung disease. Conservative management induces spontaneous ductus closure in <20% of extremely premature infants (infants born at <25 weeks of gestation). The aim of the present study was to determine the efficacy and safety of prophylactic indomethacin (INDO) administration for PDA closure in extremely premature infants born between 23 and 24 weeks of gestation.

METHODS

A historical case-control study of 30 infants born between 23 and 24 weeks of gestation was carried out. In the prophylactic INDO group, a 12 h-long, 0.01 mg/kg per h dose of INDO was administered within 6 h of life. During the historical control period, only infants with symptomatic PDA were treated with INDO for 1 h. The incidence of symptomatic PDA, mortality and early neonatal morbidity was compared between the two groups on Fisher's exact test and Mann-Whitney rank-sum test.

RESULTS

None of the infants in the prophylactic INDO group had symptomatic PDA, while 11 of the 15 infants in the control group showed symptomatic PDA (P < 0.001). There were no significant differences between the mortality rates and the early neonatal morbidities in the two groups.

CONCLUSIONS

Prophylactic INDO administration to extremely premature infants born between 23 and 24 weeks of gestation decreased the incidence of symptomatic PDA without increasing the incidence of adverse effects.

Renal effects of ibuprofen for the treatment of patent ductus arteriosus in premature infants

In recent years ibuprofen has been proposed for the treatment of patent ductus arteriosus (PDA) as it has been proved to be equally as effective as indomethacin and shows fewer cerebral blood flow, intestinal and renal hemodynamic effects. A number of studies and several meta-analyses comparing both drugs are now available that debate whether indomethacin or ibuprofen should be used for PDA prophylaxis or closure. This review examines the available knowledge on the specific issue of the effects of ibuprofen on kidney function, as improved renal tolerance is a major argument in favor of its use in the routine treatment of PDA. There is sufficient evidence to consider that ibuprofen, at the currently proposed dosing regimen, has a similar efficacy to indomethacin but is better tolerated by the neonatal kidney when employed for the treatment of established PDA. However, adverse effects of ibuprofen have been evidenced both in trials on the use of ibuprofen for the prevention of PDA and of intraventricular hemorrhage-periventricular hemorrhage (IVH-PVH), and in experimental studies on a neonatal, anesthetized animal model. Thus ibuprofen, as with other cyclooxygenase (COX) inhibitors, may not be exempt from causing renal adverse effects, especially in circumstances when renal prostaglandin activation is maximal (i.e., when administrated early after birth, in more immature patients and in certain situations such as in the anesthetized rabbit). However, although the issue has been addressed extensively in the last decades, there is insufficient evidence that therapeutic intervention in PDA is beneficial in terms of mortality or clinically significant morbidity outcomes. Studies aimed at resolving this key issue are still needed.

Effects of a patent ductus arteriosus on postprandial mesenteric perfusion in premature baboons

BACKGROUND

Superior mesenteric artery flow increases after a feeding to meet the intestines' increased metabolic demands. Although a patent ductus arteriosus can affect superior mesenteric artery perfusion in nonfeeding infants, there is no information about its effects on the hyperemic response that follows a feeding.

OBJECTIVE

Our goal was to study the effects of a patent ductus arteriosus on superior mesenteric artery perfusion in preterm baboons.

DESIGN

Preterm baboons were delivered at 67% gestation and ventilated for 14 days. Enteral feedings were begun and advanced per protocol. Feeding studies were performed between days 10 and 14. Thirty-one studies were performed in animals with a closed ductus; 21 studies in those with a moderate patent ductus arteriosus shunt (pulmonary-to-systemic blood flow ratio>or=2:1). Two-dimensional echocardiographic and Doppler examinations were performed before and 10 and 30 minutes after a feeding. The groups were similar in birth weights, feeding volumes, and age at time of study.

RESULTS

During the preprandial period, baboons with a moderate patent ductus arteriosus had significantly lower blood pressures and systemic blood flows than animals with a closed ductus. Preprandial superior mesenteric artery-blood flow velocities did not differ between the open and closed ductus groups. Animals with a closed ductus increased their superior mesenteric artery-velocities (diastolic and mean) and decreased their superior mesenteric artery relative-vascular-resistance (mean blood pressure/mean superior mesenteric artery-velocity) by 10 minutes after the feeding. By 30 minutes after the feeding, the values were returning to their preprandial values. In contrast, in baboons in the patent ductus arteriosus group, there were no significant changes in superior mesenteric artery-velocity or resistance after the feeding, and superior mesenteric artery-velocities were significantly lower than those in the closed ductus group.

CONCLUSIONS

A moderate patent ductus arteriosus shunt limits the ability of the preterm newborn baboon to increase its postprandial mesenteric blood flow velocity. We speculate that this may interfere with its ability to meet increased intestinal metabolic demands and may contribute to feeding difficulties.

Ibuprofen versus continuous indomethacin in premature neonates with patent ductus arteriosus: is the difference in the mode of administration?

Ibuprofen has been proposed as a preferential alternative to indomethacin in treating patent ductus arteriosus (PDA), because it is purported to have less renal, mesenteric, and cerebral vasoconstrictive effects. However, short and long-term safety concerns regarding ibuprofen remain. Continuous slow infusion of indomethacin also eliminates peripheral vasoconstriction and may thus offer similar benefits to ibuprofen without safety concerns. In this study, our objective was to show that treating a PDA with continuous indomethacin is similar to ibuprofen in its effect on urine output, renal function, and blood flow velocities in the renal, superior mesenteric, and anterior cerebral arteries. Sixty four prematures with PDA were randomly, prospectively assigned to either treatment. PDA closure rates were similar (74 versus 59%; p = 0.123). Nine indomethacin-treated babies (29%) versus twelve ibuprofen babies (38%) underwent repeated therapy (p = 0.656). Two indomethacin and four ibuprofen infants required surgical ligation (p = 0.672). Serum creatinine, oliguria, estimated glomerular filtration rate, and fractional excretion of sodium were similar in both groups, as were blood flow velocity parameters in the vessels studied. There were no differences in necrotizing enterocolitis, BPD, intraventricular hemorrhage, and/or retinopathy of prematurity. In conclusion, PDA treatment with either continuous indomethacin infusion or ibuprofen was equally devoid of adverse renal effects and/or peripheral vasoconstrictive effects.

Continuous infusion versus intermittent bolus doses of indomethacin for patent ductus arteriosus closure in symptomatic preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used for the prevention and the treatment of patent ductus arteriosus (PDA). Although a 3-dose schedule has been commonly used, there is no consensus on optimal dosage and duration of indomethacin therapy for PDA closure. There are potential adverse effects of indomethacin use in premature infants such as a reduction in cerebral, mesenteric and renal blood flow and platelet dysfunction. Administering indomethacin continuously over 36-hours has been suggested as a safer and more effective option to prevent such adverse effects.

OBJECTIVES

To compare the efficacy and safety of continuous infusion versus bolus administration of indomethacin in closing a symptomatic PDA in preterm infants.

SEARCH STRATEGY

The standard search strategy of Cochrane Neonatal Review was used: MEDLINE and EMBASE (1966 - March 2007), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2007), bibliographies of reviews and trials were examined for references to other trials, previous symposia proceedings published in Pediatric Research (Pediatric Academic Societies Annual Meeting Abstract Book, 1972 - 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing continuous indomethacin infusion to bolus doses for closure of a symptomatic PDA in preterm infants with a symptomatic PDA diagnosed clinically and/or by echocardiography.

DATA COLLECTION AND ANALYSIS

The methodological quality of each study was assessed. Authors were contacted regarding missing data as well as to inquire about the outcomes that were not reported. Meta-analysis was performed to calculate relative risk (RR), risk difference (RD) and 95% confidence intervals (CI).

MAIN RESULTS

Only two small trials comparing continuous versus bolus indomethacin were eligible. Analysis of these studies showed that, although the primary outcome of PDA closure on days two and five slightly favored bolus administration, there was no statistical difference between the two groups. The estimates for PDA closure were RR 1.57 (95% CI 0.54, 4.60), RD 0.10 (95% CI -0.13, 0.33) for day 2 and RR 2.77 (95% CI 0.33, 23.14), RD 0.15 (95% CI -0.13, 0.42) for day five. There was no statistical difference between the bolus and continuous groups for the secondary outcomes of reopening of PDA, neonatal mortality, intraventricular hemorrhage (IVH) and necrotizing enterocolitis (NEC). These analyses were based on a very small number of events reported by these trials. None of the trials reported on outcomes such as requirement for retreatment with indomethacin or surgical ligation, mortality, bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), neurodevelopmental outcome and isolated intestinal perforation. The review demonstrated that there was a decrease in cerebral blood flow velocity after bolus injections and that the difference between the bolus and continuous infusion groups remained significant for 12 - 24 hour. In one study (Christmann 2002), the decrease in blood flow was maximum at 10 minutes [MD -46.40 (95% CI -75.41, -17.39)], while the other study (Hammerman 1995) reported a maximum drop at 30 minutes [MD -55.60 (95% CI -62.92, -48.28)]. Similar decrease in blood flow to the renal and mesenteric circulations following bolus administration was reported in one study (Christmann 2002). In both of these circulations, the decrease was maximum 30 minutes after the bolus injection [typical estimates for renal and mesenteric circulations, respectively: MD -42.00 (95% CI -76.59, -7.41) and MD -26.50 (95% CI -45.34, -7.66)] and lasted about two hours. None of the trials detected predefined levels of decreased urine output and increased levels of BUN and creatinine.

AUTHORS' CONCLUSIONS

Due to a paucity of events and lack of precision, the available data was found to be insufficient to draw conclusions regarding the efficacy of continuous indomethacin infusion versus bolus injections for the treatment of PDA. Although continuous indomethacin seems to cause less alterations in cerebral, renal and mesenteric circulations, the clinical meaning of this effect is unclear. Definitive recommendations about the preferred method of indomethacin administration i.e. continuous versus bolus infusions for the treatment of PDA in premature infants cannot be made based on the current findings of this review.

Nasal continuous positive airway pressure affects pre- and postprandial intestinal blood flow velocity in preterm infants

OBJECTIVE

To measure the effect of nasal continuous positive airway pressure (CPAP) on intestinal blood flow velocity responses to enteral feedings and left ventricular output (LVO).

STUDY DESIGN

Eighteen infants completed the study (birth weight 1793+/-350 g, gestational age 32.1+/-1.1 weeks). On the day infants were weaned from CPAP to room air, pre- and postprandial (0, 30, 60 and 90 min after feeding) mean velocity (MV), peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured for one feeding given when receiving CPAP ('on CPAP'), and for one feeding given after CPAP had been discontinued ('off CPAP'). Preprandial LVO was measured before and after CPAP discontinuation.

RESULT

MV and PSV were significantly lower when infants were on CPAP (P<0.05). Maximum postprandial MV, PSV and EDV occurred at 30 min when on CPAP and at 60 min when off CPAP. Preprandial LVO was similar when infants were on and off CPAP.

CONCLUSION

CPAP administration affects pre- and postprandial intestinal blood flow velocity, which may impact tolerance to enteral feedings.

Clinical considerations for the pharmacologic management of patent ductus arteriosus with cyclooxygenase inhibitors in premature infants

When medical management is warranted for closure of a persistent patent ductus arteriosus (PDA) in premature infants, treatment with a cyclooxygenase (COX) inhibitor is indicated. Indomethacin, available since 1976, has been the conventional pharmacologic treatment for PDA, but its use is associated with vasoconstrictive effects that impair renal, mesenteric and cerebral blood flow. Intravenous (IV) ibuprofen lysine, approved in the United States in 2006, has less severe vasoconstrictive effects on these vital organs than IV indomethacin. Clinical trials have shown both of these COX inhibitors to be equally effective in closing the PDA in approximately 70%-80% of treated infants, with less vasoconstrictive and adverse renal effects occurring with IV ibuprofen lysine.1,2 Several clinical considerations are important in the process of medical decision-making when faced with the need for PDA treatment with one of these pharmacologic agents in the premature infant. This paper focuses on these clinical considerations, including cerebral, renal and mesenteric blood flow, renal function, pulmonary effects, protein-binding capacity as it relates to hyperbilirubinemia, and platelet aggregation. No differences in chronic lung disease, pulmonary hypertension, hyperbilirubinemia and coagulopathy were observed in clinical trials when comparing these 2 COX inhibitors; however, significant differences have been observed in arterial blood flow to the cerebral, renal and mesenteric organs, suggesting that IV ibuprofen lysine may be the more favorable agent.

Umbilical artery catheters do not affect intestinal blood flow responses to minimal enteral feedings

OBJECTIVE

To investigate the effects of umbilical artery catheters (UACs) on superior mesenteric artery (SMA) blood flow velocity (BFV) following enteral feedings in very low birth weight preterm infants.

STUDY DESIGN

Very low birth weight preterm infants who had UACs inserted as part of standard clinical care were enrolled in this prospective study. On the day the UAC was scheduled to be removed, pre- and postprandial SMA BFV (mean, peak systolic and end diastolic velocities) were measured in conjunction with a minimal enteral feeding given while the UAC was in place. The same measurements were made with the next feeding given after the UAC was removed. Preprandial measurements were made at least 3 h after the last enteral feeding, and postprandial measurements were made 30, 45 and 60 min after the feeding began. The same volume and type of feeding were used for both studies.

RESULTS

The birth weight and gestational age of the 19 infants who completed the study were 1014+/-221 g and 27.4+/-1.9 weeks, respectively. Infants were 4.6+/-1.7-days-old when the first SMA BFV measurement was made, the volume of enteral feedings was 1.3+/-0.6 ml, and the time between the two enteral feedings was 4.7+/-3.2 h. Preprandial SMA BFV did not differ with the UAC in place compared with the UAC removed. Peak postprandial velocities were at 45 min after feedings began. The percent increase from baseline was not significantly different with the UAC in place compared with the UAC removed.

CONCLUSIONS

Preprandial SMA BFV and postprandial SMA BFV responses to minimal enteral feedings were not affected by the presence of a UAC.

Factors that influence mesenteric artery blood flow velocity in newborn preterm infants

OBJECTIVES

To identify demographic and clinical variables that relate to the postnatal increase in intestinal blood flow velocity in preterm infants.

STUDY DESIGN

Fasting or preprandial peak systolic velocity (PSV) and time-averaged mean velocity (TAMV) in the superior mesenteric artery were measured once each day for the first 5 days of life. We investigated the relationship between blood flow velocity and the following variables: birth weight, gestational age, feeding volumes, number of days to reach full feeding volumes, type of feeding given, continuous positive airway pressure (CPAP) administration and hyperalimentation (HAL) administration.

RESULTS

Twenty-five infants with a mean birth weight of 1740 g and mean gestational age of 31.8 weeks were studied. There were significant increases in PSV (P < 0.001) and TAMV (P = 0.005) from postnatal day 1 to 5. The postnatal increase in TAMV and PSV was attenuated in infants administered CPAP or HAL for > or =3 days; the results remained significant after controlling for birth weight and gestational age. There was a significant correlation (P < 0.02) between volume of enteral feedings given on 2 of 5 days for TAMV, and on 1 of 5 days for PSV.

CONCLUSIONS

These data support previous findings of significant increases in intestinal blood flow in preterm infants during the first week of life, and of inconsistent effects of enteral feeding volumes on fasting or preprandial intestinal blood flow. The reasons for, and the clinical implications of, attenuated increases in postnatal intestinal blood flow in infants on CPAP or HAL require further investigation.

Ibuprofeno frente a indometacina en el tratamiento del conducto arterioso persistente del prematuro

INTRODUCTION

Persistent patent ductus arteriosus (PDA) is a common entity in preterm infants. The most commonly used pharmacological treatment to close the ductus is indomethacin but it can affect cerebral, renal and mesenteric blood flow. Ibuprofen has recently been shown to be effective in closing PDA with fewer hemodynamic effects. In this study we compared the safety and efficacy of ibuprofen and indomethacin in the treatment of PDA in preterm infants.

MATERIAL AND METHODS

A randomized trial was performed. Premature infants with symptomatic PDA confirmed by echocardiography in the first week of life and who required respiratory support were included. The patients were randomly assigned to receive either intravenous indomethacin or ibuprofen. The rate of ductal closure, need for additional treatment, complications, and clinical course were evaluated.

RESULTS

Twenty-four patients were treated with indomethacin and 23 with ibuprofen. The clinical characteristics before treatment were similar in both groups. Both treatments were effective in closing PDA (87.5% in the indomethacin group and 82.6% in the ibuprofen group). The two cohorts did not differ in the rate of reopening, need for a second pharmacologic treatment, or surgical ductal ligation. No patient in the ibuprofen group developed gastrointestinal adverse effects, but two infants in the indomethacin group had isolated bowel perforation and one had necrotizing enterocolitis. Transient renal dysfunction developed in seven patients (29%) in the indomethacin group versus two (9%) in the ibuprofen group. Transient renal insufficiency was found in one patient in the indomethacin group and in none in the ibuprofen group. The rate of other complications was similar in both groups.

CONCLUSIONS

In our trial ibuprofen was as effective as indomethacin in closing PDA. No significant differences were found in the incidence of complications but fewer renal complications and no gastrointestinal complications were found in the ibuprofen group.

The hemodynamic effects of neonatal patent ductus arteriosus shunting on superior mesenteric artery blood flow

OBJECTIVE

To determine if the ratio of the pulsatility index (PI) of the left pulmonary artery to the PI of the descending aorta, the Rp/Rs index, correlates with the degree of ductal steal from the intestine in neonates with a patent ductus arteriosus (PDA).

STUDY DESIGN

Echocardiograms and Doppler studies of the superior mesenteric artery (SMA) were performed in 41 neonates less than 35 weeks gestational age with a hemodynamically significant PDA (hsPDA).

RESULTS

There was a significant negative correlation between the Rp/Rs index and the SMA PI after controlling for ductal size (r=-0.476, p<0.008).

CONCLUSIONS

The Rp/Rs index can be used as an indicator of ductal steal on intestinal blood flow. The Rp/Rs index may be a useful adjunct to existing and new techniques for improving early assessment and treatment of hsPDA, and for evaluating the effects of hsPDA on systemic organs.

Enteral feeding for high-risk neonates: a digest for nurses into putative risk and benefits to ensure safe and comfortable care

Enteral feeding is considered a relatively safe method of providing nutritional support to high-risk neonates. Nonetheless, there are associated risks, which can be classified as follows: factors to consider before initiating enteral feeding; feeding tube placement; delivery of milk feedings; and gastrointestinal, environmental, and technical factors. For each classification, this article highlights adverse consequences and synthesizes the literature for evidence-based nursing practice recommendations, which are summarized in the "Conclusion" section. Many gaps are identified in the research literature, and directions for future research are described to ensure safe and comfortable care for high-risk neonates receiving enteral feedings.

Virtual elimination of necrotising enterocolitis for 5 years - reasons?

A standardised feeding regimen was adopted in 1997 for guiding enteral feeding of neonates <32 weeks' gestation during clinical trials (18 months each) involving erythromycin (n=73) as a prokinetic and carboxymethylcellulose (n=70) as a laxative as well as for during 2 years (n=155) without any trials. Most aspects of the feeding regimen (e.g., milk increments-total volume/day, use of breast milk by choice, etc) were not significantly different from current practices.

RESULTS

298 neonates <32 weeks' gestation (<28 weeks; n=78) were enterally fed during the 5 years. Their demographic characteristics and median (interquartile) age in days at starting (AST) and days to reach full enteral feeds (FFT) of 150 ml/kg/day were not significantly different during these 5 years: [AST: 5 (3-7.5)], [FFT: 4 (3-7)] Only one case of definite NEC (> or =Stage II) occurred during the 5 years. The time to reach full feeds was also reduced by over 54% (including for neonates <28 weeks gestation) compared with a historical cohort.

CONCLUSION

Sustained reduction in the time to reach full feeds with virtual elimination of > or =Stage II NEC for 5 years indicates continued benefits of a standardised feeding regimen as a simple preventive strategy to prevent NEC. Whether our specific policy of no enteral feeds in presence of hemodynamic instability associated with PDA requiring indomethacin, and/or sepsis played a role in achieving the significant results needs controlled trials.

Closure of patent ductus arteriosus with oral ibuprofen suspension in premature newborns: a pilot study

OBJECTIVE

Patent ductus arteriosus (PDA), a common finding among premature infants, is conventionally treated by intravenous indomethacin. Intravenous ibuprofen was recently shown to be as effective and to have fewer adverse reactions in preterm infants. If equally effective, then oral ibuprofen for PDA closure would have several important advantages over the intravenous route. This study was designed to determine whether oral ibuprofen treatment is efficacious and safe in closure of a PDA in premature infants with respiratory distress syndrome.

METHODS

Twenty-two preterm newborns (gestational age: 27.5 +/- 1.75 [range: 23.9-31 weeks]; weight: 979 +/- 266 [range: 380-1500 g]) with PDA and respiratory distress syndrome were studied prospectively. They received oral ibuprofen suspension 10 mg/kg/body weight for the first dose, followed at 24-hour intervals by 2 additional doses of 5 mg/kg each, if needed, starting on the second day of life. Echocardiography was performed before treatment and 24 hours after each dose. Every child underwent cranial ultrasonography before and after each ibuprofen dose. The rate of ductal closure, the need for additional treatment, side effects, complications, and the infants' clinical courses were recorded.

RESULTS

Ductal closure was achieved in all newborns except for 1 (95.5%), in whom clinically nonsignificant ductal shunting persisted. No infant required surgical ligation of the ductus. There was no reopening of the ductus after closure had been achieved. Fourteen newborns were treated with 1 dose of ibuprofen, 6 were treated with 2 doses, and the remaining 2 were treated with 3 doses. The survival rate at 1 month was 86.4% (19 of 22). Three (13.6%) infants died from the following causes: 1 who was born at 24 weeks' gestation with a birth weight of 380 g died as a result of extreme prematurity complications, necrotizing enterocolitis, and low birth weight; 1 died as a result of Candida sepsis; and the third died as a result of Klebsiella sepsis. Intraventricular hemorrhage was observed in 7 infants. The classification was changed from grade 2 to grade 3 in 1 and from grade 0 to grade 1 or higher in 3 others. The rate of survival to discharge was 86.4% (19 of 22). No bronchopulmonary dysplasia was observed in the study group, and there was no case of tendency to bleed. There were no significant differences in the levels of serum creatinine before and after treatment with oral ibuprofen.

CONCLUSIONS

Oral ibuprofen suspension may be an effective and safe alternative for PDA closure in premature infants with PDA. However, larger comparative studies are warranted.

Cardiocirculatory effects of patent ductus arteriosus in extremely low-birth-weight infants with respiratory distress syndrome

BACKGROUND

Cardiocirculatory effects of hemodynamically significant patent ductus arteriosus (hsPDA) have not been systematically studied in extremely low-birth-weight (ELBW) infants with respiratory distress syndrome (RDS). The objective of the present study was to evaluate the effects of hsPDA on the left ventricular output (LVO) and organ blood flows in ELBW infants with RDS.

METHODS

Extremely low-birth-weight infants (birth-weight <1000 g) treated with surfactant for RDS were studied by serial Doppler flow examinations. Doppler flow variables in 19 infants in whom hsPDA developed (hsPDA group) were compared with those in 19 infants without hsPDA matched for gestational age, birth-weight, and postnatal age (non-hsPDA group). All infants in the hsPDA group had pharmacologic closure of ductus arteriosus when hsPDA developed.

RESULTS

Before pharmacological closure of PDA, the hsPDA group had significantly higher LVO, lower blood flow volume of the abdominal aorta, and lower mean blood flow velocities in the celiac artery, superior mesenteric artery, and renal artery than the non-hsPDA group. These alterations in the hsPDA group reverted to the levels in the non-hsPDA group after the closure of PDA and had no deleterious effects on the cardiorespiratory status. No significant differences between the groups were found in mean blood flow velocities of the anterior cerebral artery throughout the study period.

CONCLUSION

These results indicate that although LVO is increased, the splanchnic and renal blood flows are decreased when hsPDA develops in ELBW infants with RDS. The effects of these alterations of LVO and organ blood flows on the cardiorespiratory course seem to be minor when early pharmacologic closure of PDA is done.

Prophylactic indomethacin reduces grades III and IV intraventricular hemorrhages when compared to early indomethacin treatment of a patent ductus arteriosus

OBJECTIVE

To determine the relative risk of severe intraventricular hemorrhage (IVH) between two very early indomethacin treatment strategies.

STUDY DESIGN

Retrospective chart review of infants <29 weeks gestation and <1350 g who received either indomethacin prophylaxis or very early echocardiography with indomethacin treatment only if the ductus arteriosus was patent.

RESULTS

A total of one hundred and two infants received prophylactic indomethacin (pINDO). Echochardiography was performed on 158 infants, of whom 117 received indomethacin. Infants receiving pINDO had lower gestational age, but similar birth weight, gender, race, antenatal steroid exposure, delivery mode, Apgar scores, and need for resuscitation as infants evaluated by echocardiography. Grades III to IV IVH was observed less frequently in infants who received pINDO (OR 0.27, 95% CI 0.10 to 0.77, p=0.014). Frequency of side effects and recurrent patent ductus arteriosus did not differ between treatment groups.

CONCLUSION

pINDO reduces severe IVH when compared to an early echocardiography strategy.

Regional hemodynamic effects of dopamine in the indomethacin-treated preterm infant

OBJECTIVE

We have previously demonstrated that dopamine induces selective renal vasodilation without affecting cerebral and mesenteric blood flow in < or = 32 weeks' gestation normotensive preterm infants during the first postnatal day. In the present study, we have examined whether pretreatment with indomethacin affects the regional hemodynamic response to dopamine in >1-day-old normotensive preterm infants with similar gestational age.

STUDY DESIGN

The pulsatility index (PI) was used to assess the dopamine-induced changes in renal, mesenteric, and cerebral blood flow using color Doppler ultrasonography in 20 indomethacin-treated normotensive preterm neonates with patent ductus arteriosus (gestational age: 27.2+/-1.5 weeks; postnatal age: 35.7+/-8.2 hours). Dopamine (5 microg/kg per minute) was started 4.9+/-2.1 hours (range: 2 to 8 hours) after the first dose of indomethacin to combat oliguria and/or impaired peripheral perfusion. Blood flow velocity measurements were obtained immediately before and 10 minutes after the start of dopamine with each subject serving as his/her own control.

RESULTS

Dopamine increased heart rate and urine output but did not affect blood pressure at the dose applied. Dopamine decreased the PI in the renal and superior mesenteric artery (2.6+/-1.32 vs. 1.61+/-0.7 and 2.36+/-1.12 vs. 1.76+/-0.64, respectively; p<0.05) whereas the PI in the middle cerebral artery remained unchanged. These results are consistent with a dopamine-induced increase in renal and mesenteric blood flow without an effect on cerebral blood flow.

CONCLUSIONS

When started at least 2 hours after the first dose of indomethacin, dopamine induces renal and mesenteric vasodilation without affecting cerebral hemodynamics in the >1-day-old indomethacin-treated preterm infant.

Evidence-based feeding guidelines for very low-birth-weight infants

Clinical practice guidelines (CPG) for the nutritional management of premature infants are limited. This project focused on the development of a research-based enteral feeding CPG for infants of < 1,500 g. The CPG was based on an extensive literature review and developed through a process of consensus decision making by a team of clinical researchers. Infants that weigh < 1,000 g initiate minimal enteral nutrition (MEN) at 48 hours; nutritional feedings begin on day 5 to 6 of life. For infants between 1,000 and 1,500 g, nutritional feedings begin at 48 hours and are advanced at a rate of less than 30 mL/kg per day. The benefits and risks of continuous versus intermittent nasogastric tube feeding were inconclusive; therefore, the CPG does not stipulate a feeding method. Breast milk is used preferentially, and specific guidelines for the definition and management of feeding intolerance are provided. A follow-up study testing this CPG has been completed and is published in the original research section of this issue.

Variations in prevalence of hypotension, hypertension, and vasopressor use in NICUs

OBJECTIVE

Very low birth weight infants are vulnerable to hypotension and its associated complications. Vasopressors are used to raise blood pressure (BP), but indications for use are uncertain. Our objectives were (1) to study variations in BP stability among NICUs, (2) to investigate inter-NICU differences in vasopressor use, and (3) to address the association between intraventricular hemorrhage (IVH) and abnormal BPs.

STUDY DESIGN

A total of 1288 infants with birth weight <1500 g were admitted to six NICUs in Massachusetts and Rhode Island over 21 months. The lowest and highest mean BPs were collected within the first 12 hours. Also recorded were the use of vasopressors within the first 24 hours and the occurrence of IVH. Logistic regressions were used to model outcomes, controlling for gestational age and illness severity using the Score for Neonatal Acute Physiology.

RESULTS

Two of the six NICUs had significantly higher percentages of infants with at least one hypotensive BP, with prevalences of 24% to 45%. Percentages of infants treated with vasopressors ranged from 4% to 39%. This range of vasopressor use could not be explained by inter-NICU differences in birth weight, illness severity, or rates of hypotension. We found a borderline association between severe IVH and hypotension (odds ratio 1.6, p=0.055), but not between severe IVH and hypertension.

CONCLUSION

Wide differences exist in the prevalence of hypotension, hypertension, and vasopressor use among NICUs. We also found an association between hypotension and IVH, but not between hypertension and IVH.

Superior mesenteric artery blood flow velocity in small for gestational age infants of very low birth weight during the early neonatal period

In order to elucidate intestinal blood flow after birth in infants with intrauterine growth retardation, we measured superior mesenteric artery blood flow velocity in uncomplicated small for gestational age infants with a birth weight of < 1500 g by pulsed Doppler ultrasound in days 1 to 7 of life. Peak systolic blood flow velocity, time-averaged mean blood flow velocity and end-diastolic blood flow velocity in the superior mesenteric artery significantly increased with time. The resistance index and relative vascular resistance in the superior mesenteric artery significantly decreased after birth. Compared with gestational age matched appropriate for gestational age infants and birth weight matched appropriate for gestational age ones, peak systolic blood flow velocity, time-averaged mean blood flow velocity and end-diastolic blood flow velocity in the superior mesenteric artery were lower in the small for gestational age infants. The difference between the small for gestational age group and the gestational age matched appropriate for gestational age group was statistically significant. The resistance index and relative vascular resistance in the superior mesenteric artery tend to be higher in the small for gestational age group than in the appropriate for gestational age groups. In conclusion, although intestinal blood flow velocity in infants with intrauterine growth retardation increases after birth, it is lower than appropriate for gestational age infants during the early neonatal period.

Erythropoietin and the incidence of necrotizing enterocolitis in infants with very low birth weight

BACKGROUND/PURPOSE

The presence of erythropoietin (Epo) in human milk and the expression of Epo receptors on intestinal villous enterocytes of neonates suggest that Epo has a role in growth and development of the gastrointestinal tract. On this basis, the authors hypothesized that recombinant Epo (rEpo) given for prevention or treatment of the anemia of prematurity would protect against necrotizing enterocolitis (NEC).

METHODS

A retrospective cohort study was conducted from a university neonatal intensive care unit of 483 very low birth weight (500 to 1,250 g) neonates born from July 1, 1993 to January 1, 1998.

RESULTS

A total of 260 neonates received rEpo, and 223 did not (control group). The rEpo and control groups were similar in gender distribution (52% v. 48% boys), gestational age (26.8+/-2.1 v. 27.6+/-2.9 weeks; mean +/- SD), birth weight (895+/-198 v. 911+/-208 g), 1 and 5 minute Apgar scores (4.2 and 6.1 v4.7 and 6.7), and incidence of severe intraventricular hemorrhage (8.9% v. 10.3%). The rEpo group had a lower incidence of NEC (12 of 260, 4.6% v. 24 of 223, 10.8%; P = .028, 95% confidence interval for difference: -0.108 to -0.015).

CONCLUSION

In very low birth weight infants, the incidence of NEC is lower in those who received rEpo.

Randomized double-blind controlled trial comparing the effects of ibuprofen with indomethacin on cerebral hemodynamics in preterm infants with patent ductus arteriosus

A prospective randomized controlled trial was performed to compare the effects of ibuprofen with indomethacin on cerebral hemodynamics measured using near infrared spectroscopy in preterm infants during treatment for patent ductus arteriosus. Infants were randomly assigned to three intravenous doses of either indomethacin (0.20-0.25 mg/kg, 12 hourly) or ibuprofen (5-10 mg/kg, 24 hourly) and also received a dose of saline. The primary end points of the study were the effects of the first dose on cerebral blood flow (CBF) and cerebral blood volume. Fifteen infants received indomethacin and 18 received ibuprofen. The group mean (SD) values for CBF (mL x 100 g(-1) x min(-1)) before and after the first dose of indomethacin were 13.6 (4.1) and 8.3 (3.1), respectively, the change being significant (p<0.001). In contrast, no significant changes in CBF were observed with the first dose of ibuprofen, the respective before and after values being 13.3 (3.2) and 14.9 (4.7) mL x 100 g(-1) x min(-1). The median (interquartile range) value for change in cerebral blood volume (mL/100 g) after the first dose in the indomethacin group was -0.4 (-0.3 to -0.6) and in the ibuprofen group was 0.0 (0.1 to -0.1), the difference between the two groups being significant (p<0.001). Cerebral oxygen delivery changed significantly after the first dose in the indomethacin group but not in the ibuprofen group. Significant reductions in CBF, cerebral blood volume, and cerebral oxygen delivery also occurred after the 24-h dose of indomethacin, but there were no significant changes after the 48-h dose of saline in the indomethacin group or after the 24- and 48-h doses of ibuprofen. The patent ductus arteriosus closure rates after indomethacin and ibuprofen were 93 and 78%, respectively. We conclude that ibuprofen, unlike indomethacin, has no adverse effects on cerebral hemodynamics and appears to mediate patent ductus arteriosus closure.

Effects of indomethacin and ibuprofen on mesenteric and renal blood flow in preterm infants with patent ductus arteriosus

OBJECTIVE

To evaluate the effect of intravenous ibuprofen and indomethacin for treatment of patent ductus arteriosus (PDA) on mesenteric and renal blood flow velocity in preterm infants.

STUDY DESIGN

Seventeen mechanically ventilated preterm infants (<33 weeks' gestation) with PDA received either 0.2 mg/kg indomethacin (n = 8) or 10 mg/kg ibuprofen (n = 9), infused over 15 minutes. Mesenteric and renal blood flow velocity were measured by using Doppler ultrasonography.

RESULTS

Indomethacin caused a significant reduction in mesenteric and renal blood flow velocity 30 minutes after drug administration; mesenteric and renal blood flow velocity did not return to the pretreatment values by 120 minutes. Ibuprofen did not alter blood flow 30 minutes after treatment, and blood flow increased 120 minutes after treatment. Mesenteric and renal blood flow velocity changes were significantly different between the 2 treatment groups.

CONCLUSIONS

Compared with indomethacin, ibuprofen did not significantly reduce mesenteric and renal blood flow velocity.

Mechanisms of blood pressure increase induced by dopamine in hypotensive preterm neonates

AIMS

To compare changes in global haemodynamics as well as anterior cerebral and superior mesenteric artery perfusion after dopamine treatment.

METHODS

Anterior cerebal and superior mesenteric artery perfusion was measured using Doppler ultrasonography in hypotensive preterm neonates in whom cardiac output increased (group 1, n=10) or decreased (group 2, n=40) after dopamine treatment.

RESULTS

Despite a lower dopamine infusion rate, the blood pressure increase (mm Hg) in group 2 [Delta=13(1); mean(SE)] exceeded that in group 1 [Delta=8(1)], while systemic vascular resistance (mm Hg/l/min/kg) rose in group 2 [Delta=106 (37)], but was unchanged in group 1 [Delta=9 (6)]. Anterior cerebral artery blood velocity and resistance were unaffected by dopamine. However, compared with unchanged values in group 1, superior mesenteric artery blood velocity fell by 14.7(4.8) cm/s and resistance increased by 4.1(0.7) mm Hg/cm in group 2.

CONCLUSIONS

These results suggest that, in a portion of hypotensive preterm neonates, the increase in blood pressure induced by dopamine is related to a predominant vasoconstrictor action and is associated with a fall in bowel perfusion.

Postnatal hemodynamic changes in very-low-birthweight infants

The purpose of this study was to characterize postnatal changes in regional Doppler blood flow velocity (BFV) and cardiac function of very-low-birthweight infants and to examine factors that might influence these hemodynamic changes. Mean and end-diastolic BFV of the middle cerebral and superior mesenteric arteries, cardiac output, stroke volume, and fractional shortening were measured in 20 infants birthweight 1,002 +/- 173 g, gestational age 28 +/- 2 wk) at 6, 30, and 54 h after birth and before and after feedings on days 7 and 14. Postnatal increases in cerebral BFV, mesenteric BFV, and cardiac output were observed that were not associated with changes in blood pressure, hematocrit, pH, arterial PCO(2), or oxygen saturation. The postnatal pattern of relative vascular resistance (RVR) differed between the cerebral and mesenteric vasculatures. RVR decreased in the middle cerebral but not the superior mesenteric artery. Physiological patency of the ductus arteriosus did not alter postnatal hemodynamic changes. In response to feeding, mesenteric BFV and stroke volume increased, and mesenteric RVR and heart rate decreased. Postprandial responses were not affected by postnatal age or the age at which feeding was initiated. However, the initiation of enteral nutrition before 3 days of life was associated with higher preprandial mesenteric BFV and lower mesenteric RVR than was later initiation of feeding. We conclude that in very-low-birthweight infants over the first week of life 1) systemic, cerebral, and mesenteric hemodynamics exhibit region-specific changes; 2) asymptomatic ductus arteriosus patency and early feedings do not significantly influence these postnatal hemodynamic changes; and 3) cardiac function adapts to increase local mesenteric BFV in response to feedings.