Controversies surrounding xanthine therapy

Caffeine dosing regimens in preterm infants with or at risk for apnea of prematurity

BACKGROUND

Very preterm infants often require respiratory support and are therefore exposed to an increased risk of bronchopulmonary dysplasia (chronic lung disease) and later neurodevelopmental disability. Caffeine is widely used to prevent and treat apnea (temporal cessation of breathing) associated with prematurity and facilitate extubation. Though widely recognized dosage regimes have been used for decades, higher doses have been suggested to further improve neonatal outcomes. However, observational studies suggest that higher doses may be associated with harm.

OBJECTIVES

To determine the effects of higher versus standard doses of caffeine on mortality and major neurodevelopmental disability in preterm infants with (or at risk of) apnea, or peri-extubation.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), and clinicaltrials.gov in May 2022. The reference lists of relevant articles were also checked to identify additional studies.

SELECTION CRITERIA

We included randomized (RCTs), quasi-RCTs and cluster-RCTs, comparing high-dose to standard-dose strategies in preterm infants. High-dose strategies were defined as a high-loading dose (more than 20 mg of caffeine citrate/kg) or a high-maintenance dose (more than 10 mg of caffeine citrate/kg/day). Standard-dose strategies were defined as a standard-loading dose (20 mg or less of caffeine citrate/kg) or a standard-maintenance dose (10 mg or less of caffeine citrate/kg/day). We specified three additional comparisons according to the indication for commencing caffeine: 1) prevention trials, i.e. preterm infants born at less than 34 weeks' gestation, who are at risk for apnea; 2) treatment trials, i.e. preterm infants born at less than 37 weeks' gestation, with signs of apnea; 3) extubation trials: preterm infants born at less than 34 weeks' gestation, prior to planned extubation.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We evaluated treatment effects using a fixed-effect model with risk ratio (RR) for categorical data and mean, standard deviation (SD), and mean difference (MD) for continuous data.  MAIN RESULTS: We included seven trials enrolling 894 very preterm infants (reported in Comparison 1, i.e. any indication). Two studies included infants for apnea prevention (Comparison 2), four studies for apnea treatment (Comparison 3) and two for extubation management (Comparison 4); in one study, indication for caffeine administration was both apnea treatment and extubation management (reported in Comparison 1, Comparison 3 and Comparison 4). In the high-dose groups, loading and maintenance caffeine doses ranged from 30 mg/kg to 80 mg/kg, and 12 mg/kg to 30 mg/kg, respectively; in the standard-dose groups, loading and maintenance caffeine doses ranged from 6 mg/kg to 25 mg/kg, and 3 mg/kg to 10 mg/kg, respectively. Two studies had three study groups: infants were randomized in three different doses (two of them matched our definition of high dose and one matched our definition of standard dose); high-dose caffeine and standard-dose caffeine were compared to theophylline administration (the latter is included in a separate review). Six of the seven included studies compared high-loading and high-maintenance dose to standard-loading and standard-maintenance dose, whereas in one study standard-loading dose and high-maintenance dose was compared to standard-loading dose and standard-maintenance dose. High-dose caffeine strategies (administration for any indication) may have little or no effect on mortality prior to hospital discharge (risk ratio (RR) 0.86, 95% confidence of interval (CI) 0.53 to 1.38; risk difference (RD) -0.01, 95% CI -0.05 to 0.03; I² for RR and RD = 0%; 5 studies, 723 participants; low-certainty evidence). Only one study enrolling 74 infants reported major neurodevelopmental disability in children aged three to five years (RR 0.79, 95% CI 0.51 to 1.24; RD -0.15, 95% CI -0.42 to 0.13; 46 participants; very low-certainty evidence). No studies reported the outcome mortality or major neurodevelopmental disability in children aged 18 to 24 months and 3 to 5 years. Five studies reported bronchopulmonary dysplasia at 36 weeks' postmenstrual age (RR 0.75, 95% CI 0.60 to 0.94; RD -0.08, 95% CI -0.15 to -0.02; number needed to benefit (NNTB) = 13; I² for RR and RD = 0%; 723 participants; moderate-certainty evidence). High-dose caffeine strategies may have little or no effect on side effects (RR 1.66, 95% CI 0.86 to 3.23; RD 0.03, 95% CI -0.01 to 0.07; I² for RR and RD = 0%; 5 studies, 593 participants; low-certainty evidence). The evidence is very uncertain for duration of hospital stay (data reported in three studies could not be pooled in meta-analysis because outcomes were expressed as medians and interquartile ranges) and seizures (RR 1.42, 95% CI 0.79 to 2.53; RD 0.14, 95% CI -0.09 to 0.36; 1 study, 74 participants; very low-certainty evidence). We identified three ongoing trials conducted in China, Egypt, and New Zealand.

AUTHORS' CONCLUSIONS

High-dose caffeine strategies in preterm infants may have little or no effect on reducing mortality prior to hospital discharge or side effects. We are very uncertain whether high-dose caffeine strategies improves major neurodevelopmental disability, duration of hospital stay or seizures. No studies reported the outcome mortality or major neurodevelopmental disability in children aged 18 to 24 months and 3 to 5 years. High-dose caffeine strategies probably reduce the rate of bronchopulmonary dysplasia. Recently completed and future trials should report long-term neurodevelopmental outcome of children exposed to different caffeine dosing strategies in the neonatal period. Data from extremely preterm infants are needed, as this population is exposed to the highest risk for mortality and morbidity. However, caution is required when administering high doses in the first hours of life, when the risk for intracranial bleeding is highest. Observational studies might provide useful information regarding potential harms of the highest doses.

Effects of early aminophylline therapy on clinical outcomes in premature infants

BACKGROUND

Aminophylline use and the association between clinical outcomes and therapy timing have been less investigated. The objective of this study was to determine the efficacy of early aminophylline use (within the first two days of life) in premature infants.

METHOD

A retrospective observational cohort of infants weighing <1500 g and <30 weeks of gestational age at Kaohsiung Veterans General Hospital received aminophylline either within the first two days of life (EA, early aminophylline group), after the third day of life (LA, late aminophylline group), or without aminophylline during the first month of life (WA, without aminophylline group). Demographic data and neonatal clinical outcomes were compared among the three groups.

RESULTS

This study included 89 preterm infants (EA = 33, LA = 38, WA = 18). The EA group had a lower incidence of bronchopulmonary dysplasia (BPD) than the WA group (adjusted odds ratio [aOR] = 8.86(1.56-59.32); P = 0.024). Although there was no significant difference in BPD incidence between the EA and LA groups (aOR = 2.66(0.51-13.81), P = 0.244), a trend remained. Birth body weight less than 1000 g was also a significant risk factor for BPD (aOR = 8.86(1.32-47.41), P = 0.014). The duration of mechanical ventilation was shorter in the infants in the EA group compared to the WA group (estimated beta = -11.344(-19.57-3.12); P = 0.008).

CONCLUSION

Early aminophylline administration may be associated with a decreased incidence of BPD in preterm infants. However, the clinical benefits of aminophylline treatment require further investigation. In addition, a birth body weight of less than 1000 g was a crucial risk factor for BPD.

What is bronchopulmonary dysplasia and does caffeine prevent it?

Bronchopulmonary dysplasia (BPD) is among the most severe complications of very premature birth. Clinical and laboratory studies indicate that lung immaturity, inflammatory lung injury, and disordered lung repair are the primary mechanisms responsible for the development of BPD. Caffeine, initiated within the first 10 days after birth, is one of few drug therapies shown to significantly decrease the risk of BPD in very low birth weight infants. This benefit is likely derived, at least in part, from reduced exposure to positive airway pressure and supplemental oxygen with caffeine therapy. Additional cardiorespiratory benefits of caffeine that may contribute to the lower risk of BPD include less frequent treatment for a PDA, improved pulmonary mechanics, and direct effects on pulmonary inflammation, alveolarization, and angiogenesis. Routine administration of caffeine is indicated in the vast majority of very low birth weight infants. However, current preventative strategies including widespread use of caffeine do not avert BPD in all cases. As such, there is continued need for novel methods to further reduce the risk of BPD in very low birth weight infants.

Potential beneficial effects of caffeine administration in the neonatal period of an animal model of schizophrenia

Obstetric complications, like maternal hypertension and neonatal hypoxia, disrupt brain development, leading to psychiatry disorders later in life, like schizophrenia. The exact mechanisms behind this risk are not yet well known. Spontaneously hypertensive rats (SHR) are a well-established model to study neurodevelopment of schizophrenia since they exhibit behavioral alterations mimicking schizophrenia that can be improved with antipsychotic drugs. SHR mothers are hypertensive, and the SHR offspring develop in preeclampsia-like conditions. Hypoxic conditions increase levels of adenosine, which play an important role in brain development. The enhanced levels of adenosine at birth could be related to the future development of schizophrenia. To investigate this hypothesis adenosine levels of brain neonatal Wistar rats and SHR were quantified. After that, caffeine, an antagonist of adenosinergic system, was administrated on PND (postnatal day) 7 (neurodevelopmental age similar to a human at delivery) and rats were observed at adolescent and adult ages. We also investigated the acute effects of caffeine at adolescent and adult ages. SHR control adolescent and adult groups presented behavioral deficits like hyperlocomotion, deficit in social interaction (SI), and contextual fear conditioning (CFC). In SHR, neonatal caffeine treatment on PND 7 normalized hyperlocomotion, improved SI, and CFC observed at adolescent period and adult ages, showing a beneficial effect on schizophrenia-like behaviors. Wistar rats neonatally treated with caffeine exhibited hyperlocomotion, deficit in SI and CFC when observed at adolescent and adult ages. Acutely caffeine treatment administrated at adolescent and adult ages increased locomotion and decreased SI time of Wistar rats and impair CFC in adult Wistars. No effects were observed in SHR. In conclusion, caffeine can be suggested as a useful drug to prevent behavioral deficits observed in this animal model of prenatal hypoxia-induced schizophrenia profile when specifically administered on PND 7.

Caffeine not associated with irritable behaviour in very low-birth-weight infants

This paper is an examination of irritable behaviour in very low-birth-weight infants in relation to caffeine or aminophylline. We assessed tremulous movement (a sub-score of General Movements Optimality Score) in 18 caffeine-treated subjects and 18 aminophylline-treated subjects. Caffeine, unlike aminophylline, was not associated with irritable behaviour at standard dose.

Diagnostic of Early Onset Polycystic Kidney Disease in Neonates

Polycystic kidney disease represented by autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) have a major impact of mortality in children. We conducted a study of a premature infant with an estimated gestation date of 32 weeks with a presumptive prenatal diagnosis of right polycystic kidney. A 28-year-old primigravida with pre-eclampsia was admitted at the gynecology unit of Clinical Emergency County Hospital of Craiova. The clinical examination revealed a large abdominal distention due probably to the right polycystic kidney, suspected on prenatal ultrasound and radiography. The preterm neonate undergone right nephrectomy 5 days after birth. Histopathology of the kidney was performed in the Pathology Department of the Emergency County Hospital of Craiova and in the Center for Microscopic Morphology and Immunology of U.M.F. of Craiova. Microscopy revealed dilated cysts lined by simple cuboidal or flattened epithelium, and islets of remnant kidney parenchyma separated by edematous stroma. Immunohistochemistry for CD34 revealed incomplete blood arcades which did not seem to be in contact with all the tubular elements of the parenchyma, when compared to a control age-matched kidney. The patient had a favorable postoperative evolution, she was clinically stable on discharge from the hospital with a follow-up strategy including genetic testing.

Antioxidative effects of caffeine in a hyperoxia-based rat model of bronchopulmonary dysplasia

Background

While additional oxygen supply is often required for the survival of very premature infants in intensive care, this also brings an increasing risk of progressive lung diseases and poor long-term lung outcomes. Caffeine is administered to neonates in neonatal intensive care for the prevention and treatment of apneas and has been shown to reduce BPD incidence and the need for mechanical ventilation, although it is still unclear whether this is due to a direct pulmonary action via antagonism of adenosine receptors and/or an indirect action. This experimental study aims to investigate the action of caffeine on the oxidative stress response in pulmonary tissue in a hyperoxia-based model of bronchopulmonary dysplasia in newborn rats.

Methods

Newborn Wistar rats were exposed to 21% or 80% oxygen for 3 (P3) or 5 (P5) postnatal days with or without recovery on room air until postnatal day 15 (P15) and treated with vehicle or caffeine (10 mg/kg) every 48 h beginning on the day of birth. The lung tissue of the rat pups was examined for oxidative stress response at P3 and P5 immediately after oxygen exposure or after recovery in ambient air (P15) by immunohistological staining and analysis of lung homogenates by ELISA and qPCR.

Results

Lungs of newborn rats, corresponding to the saccular stage of lung development and to the human lung developmental stage of preterms, showed increased rates of total glutathione and hydrogen peroxide, oxidative damage to DNA and lipids, and induction of second-phase mediators of antioxidative stress response (superoxide dismutase, heme oxygenase-1, and the Nrf2/Keap1 system) in response to hyperoxia. Caffeine reduced oxidative DNA damage and had a protective interference with the oxidative stress response.

Conclusion

In addition to the pharmacological antagonism of adenosine receptors, caffeine appears to be a potent antioxidant and modulates the hyperoxia-induced pulmonary oxidative stress response and thus protective properties in the BPD-associated animal model. Free-radical-induced damage caused by oxidative stress seems to be a biological mechanism progress of newborn diseases. New aspects of antioxidative therapeutic strategies to passivate oxidative stress-related injury should be in focus of further investigations.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1063-5) contains supplementary material, which is available to authorized users.

Role of Ectonucleotidases in Synapse Formation During Brain Development: Physiological and Pathological Implications

BACKGROUND

Extracellular adenine nucleotides and nucleosides, such as ATP and adenosine, are among the most recently identified and least investigated diffusible signaling factors that contribute to the structural and functional remodeling of the brain, both during embryonic and postnatal development. Their levels in the extracellular milieu are tightly controlled by various ectonucleotidases: ecto-nucleotide pyrophosphatase/phosphodiesterases (E-NPP), alkaline phosphatases (AP), ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases) and ecto-5'- nucleotidase (eN).

METHODS

Studies related to the expression patterns of ectonucleotidases and their known features during brain development are reviewed, highlighting involvement of these enzymes in synapse formation and maturation in physiological as well as in pathological states.

RESULTS

During brain development and in adulthood all ectonucleotidases have diverse expression pattern, cell specific localization and function. NPPs are expressed at early embryonic days, but the expression of NPP3 is reduced and restricted to ependymal area in adult brain. NTPDase2 is dominant ectonucleotidase existing in the progenitor cells as well as main astrocytic NTPDase in the adult brain, while NTPDase3 is fully expressed after third postnatal week, almost exclusively on varicose fibers. Specific brain AP is functionally associated with synapse formation and this enzyme is sufficient for adenosine production during neurite growth and peak of synaptogenesis. eN is transiently associated with synapses during synaptogenesis, however in adult brain it is more glial than neuronal enzyme.

CONCLUSION

Control of extracellular adenine nucleotide levels by ectonucleotidases are important for understanding the role of purinergic signaling in developing tissues and potential targets in developmental disorders such as autism.

Modulators of inflammation in Bronchopulmonary Dysplasia

Over 50 years after its first description, Bronchopulmonary Dysplasia (BPD) remains a devastating pulmonary complication in preterm infants with respiratory failure and develops in 30-50% of infants less than 1000-gram birth weight. It is thought to involve ventilator- and oxygen-induced damage to an immature lung that results in an inflammatory response and ends in aberrant lung development with dysregulated angiogenesis and alveolarization. Significant morbidity and mortality are associated with this most common chronic lung disease of childhood. Thus, any therapies that decrease the incidence or severity of this condition would have significant impact on morbidity, mortality, human costs, and healthcare expenditure. It is clear that an inflammatory response and the elaboration of growth factors and cytokines are associated with the development of BPD. Numerous approaches to control the inflammatory process leading to the development of BPD have been attempted. This review will examine the anti-inflammatory approaches that are established or hold promise for the prevention or treatment of BPD.

Long-term neurodevelopment outcome of caffeine versus aminophylline therapy for apnea of prematurity

OBJECTIVE

Methylxanthines are the most commonly prescribed drug in neonatal setups. However, Clinicians show indecision in choosing the right agent for Apnea of Prematurity in most of the developing countries. Present study aimed to compare rate of mortality and survival with normal neurodevelopment outcome at 18 to 24 months of corrected age, between Caffeine- and Aminophylline-treated infants for apnea of prematurity.

METHODS

240 infants were randomly allocated to caffeine and aminophylline for apnea of prematurity during February 2012 to January 2015. Long-term neurodevelopmental assessment was done only from children who had attained corrected age of 18 to 24 months during April 2014 to February 2016. Cognitive, language and motor deficits were assessed by Bayley Scale of infant and toddler development (BSID - III). Postnatal characteristics such as hearing and visual impairments during NICU stay were noted and same were followed up.

RESULTS

Infants allocated to caffeine group showed 83% less risk of getting cognitive impairment (RR 0.16; CI 95% range 0.02 to 1.36), 50% less risk of developing motor deficits (RR 0.50; CI 95% range 0.12 to 1.95) and 24% less risk of developing language problems (RR 0.76; CI 95% range 0.36 to 1.58). However in all the neurodevelopment domains the difference between groups was not statistically significant. Risk of mortality in caffeine group was 9% less over aminophylline group which was statistically non-significant (RR - 0.92; CI 95% range - 0.45 to 1.84; p = 0.81). Physical growth parameters were found to be similar in both the groups. Risk of developing visual abnormality and hearing impairments was also statistically non-significant between the groups.

CONCLUSION

Caffeine and aminophylline showed similar effects in reducing the rate of mortality and improving the survival without neurodevelopment delays; though the clinical significance of caffeine over aminophylline cannot be undermined.

Neurobehavioral Outcomes 11 Years After Neonatal Caffeine Therapy for Apnea of Prematurity

BACKGROUND AND OBJECTIVES

Caffeine is effective in the treatment of apnea of prematurity. Although caffeine therapy has a benefit on gross motor skills in school-aged children, effects on neurobehavioral outcomes are not fully understood. We aimed to investigate effects of neonatal caffeine therapy in very low birth weight (500-1250 g) infants on neurobehavioral outcomes in 11-year-old participants of the Caffeine for Apnea of Prematurity trial.

METHODS

Thirteen academic hospitals in Canada, Australia, Great Britain, and Sweden participated in this part of the 11-year follow-up of the double-blind, randomized, placebo-controlled trial. Measures of general intelligence, attention, executive function, visuomotor integration and perception, and behavior were obtained in up to 870 children. The effects of caffeine therapy were assessed by using regression models.

RESULTS

Neurobehavioral outcomes were generally similar for both the caffeine and placebo group. The caffeine group performed better than the placebo group in fine motor coordination (mean difference [MD] = 2.9; 95% confidence interval [CI]: 0.7 to 5.1; P = .01), visuomotor integration (MD = 1.8; 95% CI: 0.0 to 3.7; P < .05), visual perception (MD = 2.0; 95% CI: 0.3 to 3.8; P = .02), and visuospatial organization (MD = 1.2; 95% CI: 0.4 to 2.0; P = .003).

CONCLUSIONS

Neonatal caffeine therapy for apnea of prematurity improved visuomotor, visuoperceptual, and visuospatial abilities at age 11 years. General intelligence, attention, and behavior were not adversely affected by caffeine, which highlights the long-term safety of caffeine therapy for apnea of prematurity in very low birth weight neonates.

Caffeine controversies

PURPOSE OF REVIEW

Caffeine use in preterm infants has endured several paradigms: from standard of care to possible neurotoxin to one of the few medications for which there is evidence of bronchopulmonary dysplasia (BPD) risk reduction. The purpose of the review is to analyze this dynamic trajectory and discuss controversies that still remain after decades of caffeine use.

RECENT FINDINGS

Following concerns for caffeine safety in preterm infants, a large randomized controlled trial demonstrated a reduction in BPD and treatment for patent ductus arteriosus. The lower rate of death or neurodevelopmental impairment noted at 18-21 months was not statistically different at later timepoints; however, infants in the caffeine group had lower rates of motor impairment at 11-year follow-up. The time of caffeine therapy initiation is now substantially earlier, and doses used are sometimes higher that previously used, but there are limited data to support these practices.

SUMMARY

Caffeine therapy for apnea of prematurity (AOP) remains one of the pillars of neonatal care, although more evidence to support dosing and timing of initiation and discontinuation are needed.

Methylxanthines induce structural and functional alterations of the cardiac system in zebrafish embryos

Background

Zebrafish embryos are emerging as a model for pharmacological and toxicological studies. We used zebrafish embryos to study the general toxicity and cardiovascular effects of eight methylxanthines: aminophylline, caffeine, diprophylline, doxofylline, etophylline, 3-isobutyl-1-methylxanthine (IBMX), pentoxifylline and theophylline.

Methods

Microinjections of the eight methylxanthines were performed in 1-2 cell stage zebrafish embryos and the general toxicity and cardiovascular effects were analyzed at different time points. Embryotoxicity and teratogenicity were evaluated to understand the general toxicity of these compounds. Structural and functional alterations of the heart were evaluated to assess the cardiovascular effects.

Results

Our results showed different activity patterns of the methylxanthines drugs. Caffeine, IBMX, pentoxifylline and theophylline were highly embryotoxic and teratogenic; aminophylline, doxofylline and etophylline were embryotoxic and teratogenic only at higher doses, and diprophylline showed a minimal (<10%) embryotoxicity and teratogenicity. Most of these drugs induced structural alteration of the heart in 20-40% of the injected embryos with the maximum dose. This structural alteration was fatal with the embryos ultimately dying within 120 hpf. All the drugs induced a transient increase in heart rate at 48 hpf which returned to baseline within 96 hpf. This functional effect of methylxanthines showed similarity to the studies done in humans and other vertebrates.

Conclusion

Our results indicate the potential toxicity and teratogenicity of different methylxanthines in the embryos during embryonic development, the most sensitive period of life. Although interspecies differences need to be considered before drawing any conclusion, our study elucidated that a single exposure of methylxanthines at therapeutic range could induce cardiac dysfunction besides causing embryotoxicity and teratogenicity. Of all the drugs, diprophylline appeared to be safer, with lower degree of embryotoxicity, teratogenicity and cardiac toxicity as compared to other methylxanthines.

Electronic supplementary material

The online version of this article (10.1186/s40360-017-0179-9) contains supplementary material, which is available to authorized users.

Caffeine for apnea of prematurity: Effects on the developing brain

Caffeine is a methylxanthine that is widely used to treat apnea of prematurity (AOP). In preterm infants, caffeine reduces the duration of respiratory support, improves survival rates and lowers the incidence of cerebral palsy and cognitive delay. There is, however, little evidence relating to the immediate and long-term effects of caffeine on brain development, especially at the cellular and molecular levels. Experimental data are conflicting, with studies showing that caffeine can have either adverse or benefical effects in the developing brain. The aim of this article is to review current understanding of how caffeine ameliorates AOP, the cellular and molecular mechanisms by which caffeine exerts its effects and the effects of caffeine on brain development. A better knowledge of the effects of caffeine on the developing brain at the cellular and/or molecular level is essential in order to understand the basis for the impact of caffeine on postnatal outcome. The studies reviewed here suggest that while caffeine has respiratory benefits for preterm infants, it may have adverse molecular and cellular effects on the developing brain; indeed a majority of experimental studies suggest that regardless of dose or duration of administration, caffeine leads to detrimental changes within the developing brain. Thus there is an urgent need to assess the impact of caffeine, at a range of doses, on the structure and function of the developing brain in preclinical studies, particularly using clinically relevant animal models. Future studies should focus on determining the maximal dose of caffeine that is safe for the preterm brain.

Aminophylline-associated irritable behaviour in preterm neonates

AIM

This study investigated the effect of aminophylline on behaviour and autonomic function in the preterm period.

METHOD

Subjects were preterm infants cared for in the Oita University hospital from August 2012 to October 2014. The group that was administered aminophylline (Am+) and the group that received no aminophylline (Am-) included 11 cases that exhibited a mean gestational age of 28weeks 5days and a mean birth weight of 1109g and 8 cases that exhibited a mean gestational age of 30weeks 5days and a mean birth weight of 1223g, respectively. Intravenous aminophylline was administered continuously at a dose of 4-6mg/kg/day followed by oral therapy when the infant suffered repetitive apnoea. Two-hour video recordings were obtained every 2weeks, and electrocardiograms were performed simultaneously. Onset-offset and tremulous movements in general movement (GM) optimality list were used as indices of behaviour. Autonomic functions were investigated via heart-rate and heart-rate variability measurements using frequency domain spectral analysis and the MemCalc method. We compared indices in 4 periods: 30-31, 32-33, 34-35 and 36-37weeks gestation.

RESULTS

The Am+ group exhibited significantly low optimality of tremulous movements at 32-33weeks gestation. The autonomic parameters did not differ significantly between the Am+ and Am- groups. There was no significant correlation between GMs optimality score and serum theophylline concentration.

CONCLUSION

Aminophylline administration was associated with transient irritable behaviour without autonomic changes in the preterm period.

Different effects of postnatal caffeine treatment on two pentylenetetrazole-induced seizure models persist into adulthood

BACKGROUND

Postnatal treatment with caffeine from P7 to P11 (10 or 20 mg/kg daily) resulted in transient changes in two pentylenetetrazole (PTZ)-induced models of epileptic seizures characterized by spike-and-wave EEG rhythm in immature rats. To know if some changes persist into adulthood we studied these models in young adult Wistar rats.

METHODS

Caffeine treatment at a daily dose of 10 and/or 20 mg/kg, sc was executed during postnatal days 7-11. Rhythmic metrazol activity (RMA, model of human absences) was induced in 60-day old rats by two successive doses of PTZ (20 + 20 mg/kg, ip) while for induction of minimal clonic seizures (model of human myoclonic seizures) the second dose of PTZ was 40 mg/kg.

RESULTS

RMA episodes elicited by the 20 + 20 mg/kg dose of PTZ in adult rats exposed to caffeine at P7 to P11 were decreased. This effect was more pronounced in group treated with the higher dose of caffeine. In contrast, the lower dose of caffeine exacerbated minimal clonic seizures (both incidence and intensity were increased). In addition, some animals from the 20-mg/kg caffeine group exhibited transition to generalized tonic-clonic seizures.

CONCLUSION

Different effects of postnatal caffeine exposure persist into adulthood; the seizure ameliorating effects in a model of absences and seizure exacerbating action in a model of myoclonic seizures are dose-specific.

Miracle baby: managing extremely preterm birth in rural Uganda

Preterm birth is an important cause of neonatal morbidity and mortality globally. Uganda has one of the highest rates of preterm birth in East Africa but few resources to care for these infants. This case highlights the clinical course of an extremely premature infant born at 26 weeks gestation to a nulliparous 24-year-old woman. Her mother was involved in her care and taught the principles of kangaroo mother care. After initial problems establishing feeds she progressed well and was discharged in the fifth week of life. The case describes some of the low technology conservative and medical measures which can be used to care for neonates, such as antenatal steroids and kangaroo care. The use of antibiotics and aminophylline are also discussed. The approach to the common challenges faced by premature infants such as respiratory disease, sepsis and necrotising enterocolitis in a resource-poor environment are discussed.

Early caffeine exposure: transient and long-term consequences on brain excitability

The influence of pre- and postnatal caffeine treatment on brain excitability during development and adulthood is reviewed. Pre- and postnatal exposure to caffeine induces sex- and age-specific long-term neurochemical alterations in the brain and the behavior of rodents. Because adenosine neuromodulation is closely related to the regulation of brain excitability the increased expression in adenosine receptor system due to neonatal caffeine treatment should cause transient and permanent changes in seizure susceptibility. So far, findings have been focused on primarily developmental changes of the brain adenosine modulatory system and have demonstrated that the alterations are not restricted to a single brain region. Neurobehavioral changes and the anticonvulsant effect of early caffeine exposure are dependent on the caffeine dose, developmental stage of exposure and age of testing. Although outcomes of caffeine treatment are still a matter of debate, our review raise questions concerning the impact of early caffeine treatment on regulation of seizure susceptibility during development and adulthood.

Caffeine induces alveolar apoptosis in the hyperoxia-exposed developing mouse lung

BACKGROUND

Caffeine is a nonspecific adenosine receptor antagonist used in premature neonates to treat apnea of prematurity. While its use may reduce the incidence of bronchopulmonary dysplasia (BPD), the precise mechanisms remain unknown. Evidence of increased adenosine levels are noted in chronic lung diseases including tracheal aspirates of infants with BPD. Utilizing a well-characterized newborn mouse model of alveolar hypoplasia, we hypothesized that hyperoxia-induced alveolar inflammation and hypoplasia is associated with alterations in the adenosine signaling pathway.

METHODS

Newborn murine pups were exposed to a 14-d period of hyperoxia and daily caffeine administration followed by a 14-d recovery period in room air. Lungs were collected at both time points for bronchoalveolar lavage (BAL) analysis as well as histopathology and mRNA and protein expression.

RESULTS

Caffeine treatment increased inflammation and worsened alveolar hypoplasia in hyperoxia-exposed newborn mice. These changes were associated with decreased alveolar type II (ATII) cell numbers, increased cell apoptosis, and decreased expression of A2A receptors. Following discontinuation of caffeine and hyperoxia, lung histology returned to baseline levels comparable to hyperoxia exposure alone.

CONCLUSION

Results of this study suggest a potentially adverse role of caffeine on alveolar development in a murine model of hyperoxia-induced alveolar hypoplasia.

Caffeine protects neuronal cells against injury caused by hyperoxia in the immature brain

Caffeine administered to preterm infants has been shown to reduce rates of cerebral palsy and cognitive delay, compared to placebo. We investigated the neuroprotective potential of caffeine for the developing brain in a neonatal rat model featuring transient systemic hyperoxia. Using 6-day-old rat pups, we found that after 24 and 48h of 80% oxygen exposure, apoptotic (TUNEL(+)) cell numbers increased in the cortex, hippocampus, and central gray matter, but not in the hippocampus or dentate gyrus. In the dentate gyrus, high oxygen exposure led to a decrease in the number of proliferating (Ki67(+)) cells and the number of Ki67(+) cells double staining for nestin (immature neurons), doublecortin (progenitors), and NeuN (mature neurons). Absolute numbers of nestin(+), doublecortin(+), and NeuN(+) cells also decreased after hyperoxia. This was mirrored in a decline of transcription factors expressed in immature neurons (Pax6, Sox2), progenitors (Tbr2), and mature neurons (Prox1, Tbr1). Administration of a single dose of caffeine (10mg/kg) before high oxygen exposure almost completely prevented these effects. Our findings suggest that caffeine exerts protection for neonatal neurons exposed to high oxygen, possibly via its antioxidant capacity.

Caffeine for apnea of prematurity: a neonatal success story

Caffeine, a methylxanthine and nonspecific inhibitor of adenosine receptors, is an example of a drug that has been in use for more than 40 years. It is one of the most commonly prescribed drugs in neonatal medicine. However, until 2006, it had only a few relatively small and short-term studies supporting its use. It is thanks to the efforts of Barbara Schmidt and the Caffeine for Apnea of Prematurity (CAP) Trial Group that we now have high-quality and reliable data not only on short-term but also long-term outcomes of caffeine use for apnea of prematurity. CAP was an international, multicenter, placebo-controlled randomized trial designed to determine whether survival without neurodevelopmental disability at a corrected age of 18 months is improved if apnea of prematurity is managed without methylxanthines in infants at a high risk of apneic attacks. CAP was kept simple and pragmatic in order to allow for maximum generalizability and applicability. Infants with birth weights of 500-1,250 g were enrolled during the first 10 days of life if their clinicians considered them to be candidates for methylxanthine therapy. The most frequent indication for therapy reported in CAP was treatment of documented apnea, followed by the facilitation of the removal of an endotracheal tube. Only about 20% of the neonatologists in the trial started caffeine for the prevention of apnea and the findings of CAP cannot automatically be extrapolated to an exclusive prophylactic indication. However, recent data suggest that the administration of prophylactic methylxanthine by neonatologists is now common practice.

Effects of caffeine on cortical epileptic afterdischarges in adult rats are modulated by postnatal treatment

We have previously shown that the effect of acute caffeine injection on cortical epileptic afterdischarges (ADs) in immature rats can be modulated by the postnatal period of repeated caffeine treatment and age of testing during development. To know if these changes persist into adulthood, in the present study adult rats, previously exposed to caffeine from postnatal day 7-11 (10 and 20 mg/kg), and injected with caffeine (10 and 20 mg/kg), respectively, at P67 were compared with groups of naive rats on cortical epileptic ADs. Low-frequency stimulation of sensorimotor cortical area was applied repeatedly with increasing intensity of stimulation current. The acute caffeine injection decreased the thresholds for both the spike-and-wave ADs and accompanying clonic seizures in naive adult rats. In contrast, the acute caffeine administration applied to rats with postnatal caffeine treatment did not change the thresholds for ADs and clonic seizures. In addition, a shorter duration of ADs was registered at some stimulation intensities in rats with early postnatal caffeine administration. Present results demonstrated failure of proconvulsant effects of caffeine after repeated caffeine administration during the early postnatal period persisting up to adulthood.

Apnea of prematurity

Apnea of prematurity is a significant problem due to immaturity of the central neural control circuitry responsible for integrating afferent input and central rhythm. In this review, we provide an overview of the pathogenesis of apnea of prematurity--including our current understanding of the role that afferent input to the brain stem plays in synergy with the central pattern generation circuitry in the emergence of apnea of prematurity. We then discuss the interplay of apnea, bradycardia, desaturation, as well as the genesis of central, mixed, and obstructive apnea. Finally, we provide a summary of the physiological basis for current therapeutic approaches to treating apnea of prematurity, and conclude with an overview of proposed long-term consequences of the resultant intermittent hypoxic episodes.

The Janus face of caffeine

Caffeine is certainly the psychostimulant substance most consumed worldwide. Over the past years, chronic consumption of caffeine has been associated with prevention of cognitive decline associated to aging and mnemonic deficits of brain disorders. While its preventive effects have been reported extensively, the cognitive enhancer properties of caffeine are relatively under debate. Surprisingly, there are scarce detailed ontogenetic studies focusing on neurochemical parameters related to the effects of caffeine during prenatal and earlier postnatal periods. Furthermore, despite the large number of epidemiological studies, it remains unclear how safe is caffeine consumption during pregnancy and brain development. Thus, the purpose of this article is to review what is currently known about the actions of caffeine intake on neurobehavioral and adenosinergic system during brain development. We also reviewed other neurochemical systems affected by caffeine, but not only during brain development. Besides, some recent epidemiological studies were also outlined with the control of "pregnancy signal" as confounding variable. The idea is to tease out how studies on the impact of caffeine consumption during brain development deserve more attention and further investigation.

Transient changes of cortical interhemispheric responses after repeated caffeine administration in immature rats

Repeated postnatal caffeine treatment of rat pups led to transient developmental changes in cortical epileptic afterdischarges. To know if physiological cortical functions are also affected transcallosal evoked potentials were studied. Rat pups of the Wistar strain were injected daily with caffeine (10 or 20 mg/kg s.c.) from postnatal day (P) 7 to P11, control siblings received saline. Cortical interhemispheric responses were tested at P12, 18, 25 and in young adult rats. Amplitude of initial monosynaptic components was evaluated in averaged responses. Single pulses as well as paired and frequency (five pulses) stimulations were used. Developmental rules - highest amplitude of responses in 25-day-old rats, potentiation with paired and frequency stimulation present since P18 - were confirmed. Caffeine-treated rats exhibited transient changes: single responses were augmented in P25 if high stimulation intensity was used, paired-pulse and frequency responses were higher in experimental than in control animals at P12, the opposite change was observed in 18- and more markedly in 25-day-old rats. No significant changes were found in adult animals, monosynaptic transcallosal responses represent a simple and robust system. The developmental profile of described changes did not exactly correspond to changes in epileptic afterdischarges supporting the possibility that afterdischarges did not arise from early monosynaptic components of responses. In spite of transient nature of changes they can reflect delayed or more probably modified brain development.

Profile of nucleotide catabolism and ectonucleotidase expression from the hippocampi of neonatal rats after caffeine exposure

Nucleotides and nucleosides play an important role in neurodevelopment acting through specific receptors. Ectonucleotidases are the major enzymes involved in controlling the availability of purinergic receptors ligands. ATP is co-released with several neurotransmitters and is the most important source of extracellular adenosine by catabolism exerted by ectonucleotidases. The main ectonucleotidases are named NTPDases (1-8) and 5'-nucleotidase. Adenosine is a powerful modulator of neurotransmitter release. Caffeine blocks adenosine receptor activity as well as adenosine-mediated neuromodulation. Considering the susceptibility of the immature brain to caffeine and the need for correct purinergic signaling during fetal development, we have analyzed the effects of caffeine exposure during gestational and lactational periods on nucleotide degradation and ectonucleotidase expression from the hippocampi of 7-, 14- and 21-days-old rats. Nucleotides hydrolysis was assessed by colorimetric determination of inorganic phosphate released. Ectonucleotidases expression was performed by RT-PCR. ATP and ADP hydrolysis displayed parallel age-dependent decreases in both control and caffeine-treated groups. AMP hydrolysis increased with caffeine treatment in 7-days-old rats (75%); although there was no significant difference in AMP hydrolysis between control (non caffeine-treated) rats and 14- or 21-days caffeine-treated rats. ADP hydrolysis was not affected by caffeine treatment. Caffeine treatment in 7- and 14-days-old rats decreased ATP hydrolysis when compared to the control group (19% and 60% decrease, respectively), but 21-days-treated rats showed an increase in ATP hydrolysis (39%). Expression levels of NTPDase 1 and 5 decreased in hippocampi of caffeine-treated rats. The expression of 5'-nucleotidase was not affected after caffeine exposure. The changes observed in nucleotide hydrolysis and ectonucleotidases expression could promote subtle effects on normal neural development considering the neuromodulatory role of adenosine.

Adverse and protective influences of adenosine on the newborn and embryo: implications for preterm white matter injury and embryo protection

Few signaling molecules have the potential to influence the developing mammal as the nucleoside adenosine. Adenosine levels increase rapidly with tissue hypoxia and inflammation. Adenosine antagonists include the methylxanthines caffeine and theophylline. The receptors that transduce adenosine action are the A1, A2a, A2b, and A3 adenosine receptors (ARs). In the postnatal period, A1AR activation may contribute to white matter injury in the preterm infant by altering oligodendrocyte (OL) development. In models of perinatal brain injury, caffeine is neuroprotective against periventricular white matter injury (PWMI) and hypoxic-ischemic encephalopathy (HIE). Supporting the notion that blockade of adenosine action is of benefit in the premature infant, caffeine reduces the incidence of bronchopulmonary dysplasia and CP in clinical studies. In comparison with the adverse effects on the postnatal brain, adenosine acts via A1ARs to play an essential role in protecting the embryo from hypoxia. Embryo protective effects are blocked by caffeine, and caffeine intake during early pregnancy increases the risk of miscarriage and fetal growth retardation. Adenosine and adenosine antagonists play important modulatory roles during mammalian development. The protective and deleterious effects of adenosine depend on the time of exposure and target sites of action.

Caffeine citrate for very preterm infants: Effects on development, temperament and behaviour

AIM

To compare two dosing regimens for caffeine citrate for neonates born less than 30 weeks gestation in terms of development, temperament and behaviour.

METHODS

A multi-centre, randomised, controlled trial design was undertaken. A total of 287 infants with apnoea of prematurity or in the peri-extubation period were randomised to receive one of two dosage regimens (20 vs. 5 mg/kg/day). The main outcome measure was cognitive development at 1 year of age on the Griffiths Mental Development Scales. Secondary outcome measures included neonatal morbidity, death and disability, temperament at 1 year and behaviour at 2 years of age.

RESULTS

Data on the primary outcome were available for 190 survivors at 12 months corrected for prematurity. A significantly greater mean general quotient was found in the high-dose group (mean (standard deviation), 98.0 (13.8) vs. 93.6 (16.5), P = 0.048). On omission of two infants for whom cognitive assessment was not possible because of disability while the mean general quotient remained higher for infants in the high-dose group, this was no longer statistically significant (P= 0.075). There was a non-significant trend for benefit in the high-dose caffeine group for death or major disability, 15.4% versus 24.2%; relative risk 0.75 (95% confidence interval 0.49-1.14). No differences in the mean values between the two groups were shown for temperament and behaviour.

CONCLUSIONS

Caffeine citrate with a dosage regimen of 20 mg/kg/day did not result in adverse outcomes for development, temperament and behaviour. The borderline benefit in cognition with high-dose caffeine needs further investigation.

Correlation between serum caffeine levels and changes in cytokine profile in a cohort of preterm infants

OBJECTIVE

To determine changes in cytokine levels associated with caffeine treatment in a cohort of preterm infants.

STUDY DESIGN

For this observational prospective study, we collected clinical data from 26 preterm infants (≤ 30 weeks gestational age). In addition to caffeine levels, cytokine profiles in peripheral blood (PB) and tracheal aspirates (TA) were determined with enzyme-linked immunosorbent assay at birth, before and after (at 24 hours and 1 week) initiation of caffeine. Non-parametric statistics were applied.

RESULTS

Included infants were 26.9 ± 1.7 weeks gestational age and weighed 985 ± 202 g. At birth, all cytokine concentrations were significantly greater in TA than PB. Serum caffeine levels were 11.1 μg/mL (interquartile range, 1.85) at approximately 24 hours post-load and 16.4 (8.7) μg/mL at 1 week on treatment. At approximately 24 hours post-load, interleukin (IL)-10 levels decreased by 47.5% (P = .01) in PB and 38.5% (P = .03) in TA, whereas other cytokine levels remained unchanged. At 1 week, caffeine levels were correlated (U-shaped) with changes in proinflammatory tumor necrosis factor-α (R(2) = 0.65; P = .0008), interleukin (IL)-1β (R(2) = 0.73; P = .0007), and IL-6 (R(2) = 0.59; P = .003), whereas inversely correlated (linear) with the anti-inflammatory IL-10 (R(2) = 0.64; P = .0008). Altogether, caffeine, at serum levels ≥ 20 μg/mL, was associated with a proinflammatory profile after 1 week of treatment.

CONCLUSIONS

Caffeine treatment for apnea of prematurity correlates with changes in cytokine profile. Caffeine levels ≥ 20 μg/mL are associated with a proinflammatory profile in our cohort of preterm infants.

Methylxanthines during pregnancy and early postnatal life

World-wide, many fetuses and infants are exposed to methylxanthines via maternal consumption of coffee and other beverages containing these substances. Methylxanthines (caffeine, theophylline and aminophylline) are also commonly used as a medication for apnea of prematurity.The metabolism of methylxanthines is impaired in pregnant women, fetuses and neonates, leading to accumulating levels thereof. Methylxanthines readily passes the placenta barrier and enters all tissues and thus may affect the fetus/newborn at any time during pregnancy or postnatal life, given that the effector systems are mature.At clinically relevant doses, the major effector system for methylxanthines is adenosine receptors. Animal studies suggest that adenosine receptors in the cardiovascular, respiratory and immune system are developed at birth, but that cerebral adenosine receptors are not fully functional. Furthermore animal studies have shown protective positive effects of methylxanthines in situations of hypoxia/ischemia in neonates. Similarly, a positive long-term effect on lung function and CNS development was found in human preterm infants treated with high doses of caffeine for apneas. There is now evidence that the overall benefits from methylxanthine therapy for apnea of prematurity outweigh potential short-term risks.On the other hand it is important to note that experimental studies have indicated that long-term effects of caffeine during pregnancy and postnatally may include altered behavior and altered respiratory control in the offspring, although there is currently no human data to support this.Some epidemiology studies have reported negative effects on pregnancy and perinatal outcomes related to maternal ingestion of high doses of caffeine, but the results are inconclusive. The evidence base for adverse effects of caffeine in first third of pregnancy are stronger than for later parts of pregnancy and there is currently insufficient evidence to advise women to restrict caffeine intake after the first trimester.

Does caffeine impair cerebral oxygenation and blood flow velocity in preterm infants?

AIM

The aim of the study is to assess the effects of an intravenous 10 mg/kg loading dose of caffeine base in cerebral oxygenation, cerebral Doppler blood flow velocity and cardiac output in preterm infants.

METHODS

Preterm neonates <34 weeks gestation were investigated at 1 and 4 h following the loading dose of caffeine using Doppler cerebral sonography, cardiac echocardiography and cerebral spatially resolved near-infrared spectroscopy.

RESULTS

Forty infants were studied with a mean gestational age (mean ± standard deviation) of 27.7 (±2.5) weeks, birth weight of 1155 (±431) g and a postnatal age of 2.8 (±2.2) days. Mean Anterior Cerebral Artery peak and time average mean blood flow velocity fell significantly by 14% and 17.7%, respectively at 1 h post-caffeine loading dose, which recovered partially by 4 h. Cerebral Tissue Oxygenation Index fell from pre-dose levels by 9.5% at 1 h with partial recovery to 4.9% reduced at 4 h post-dose. There were no significant changes in left or right ventricular output, transcutaneous oxygen saturation, transcutaneous PCO(2) or total vascular resistance.

CONCLUSIONS

A loading dose of 10 mg/kg caffeine base resulted in significant reduction at 1 h post-dose in cerebral oxygenation and cerebral blood flow velocity with partial recovery at 4 h.

Caffeine in the neonatal period induces long-lasting changes in sleep and breathing in adult rats

Caffeine is commonly used clinically to treat apnoeas and unstable breathing associated with premature birth. Caffeine antagonizes adenosine receptors and acts as an efficient respiratory stimulant in neonates. Owing to its persistent effects on adenosine receptor expression in the brain, neonatal caffeine administration also has significant effects on maturation of the respiratory control system. However, since adenosine receptors are critically involved in sleep regulation, and sleep also modulates breathing, we tested the hypothesis that neonatal caffeine treatment disrupts regulation of sleep and breathing in the adult rat. Neonatal caffeine treatment (15 mg kg(-1) day(-1)) was administered from postnatal days 3-12. At adulthood (8-10 weeks old), sleep and breathing were measured with a telemetry system and whole-body plethysmography respectively. In adult rats treated with caffeine during the neonatal period, sleep time was reduced, sleep onset latency was increased, and non-rapid eye movement (non-REM) sleep was fragmented compared to controls. Ventilation at rest was higher in caffeine-treated adult rats compared to controls across sleep/wake states. Hypercapnic ventilatory responses were significantly reduced in caffeine-treated rats compared to control rats across sleep/wake states. Additional experiments in adult anaesthetized rats showed that at similar levels of arterial blood gases, phrenic nerve activity was enhanced in caffeine-treated rats. This study demonstrates that administration of caffeine in the neonatal period alters respiratory control system activity in awake and sleeping rats, as well as in the anaesthetized rats, and also has persistent disrupting effects on sleep that are apparent in adult rats.

Adjunctive therapies in chronic lung disease: examining the evidence

Chronic lung disease (CLD) or bronchopulmonary dysplasia (BPD) is one of the most common long-term complications in very premature infants. The incidence of CLD has been increasing over the past two decades in parallel with an improvement in the survival of this population. We have witnessed a revolution in the therapies that are used, either to manage these infants' respiratory distress syndrome (RDS) with an aim to prevent CLD or to manage the established condition. Several devices and strategies have been developed to provide respiratory support with minimal risk of lung injuries. Multiple adjunctive agents have also been used either to reduce the risk of CLD or to mitigate its course. There is considerable evidence supporting the use of exogenous surfactant, but unfortunately many other therapies currently used for CLD, either preventative or as a treatment, are based on very little or no evidence. The gold standard to assess a given therapy is the randomised controlled trial (RCT), designed to look at clinically meaningful outcomes and long-term safety. In this context, we discuss the support - or lack thereof - for the adjunctive therapies used in relation to CLD. Many of the therapies have been examined as systematic reviews by the Cochrane Neonatal Review Group. These reviews are noted in the references and can be easily accessed at the following website sponsored by the National Institute of Child Health and Human Development: www.nichd.nih.gov/cochrane/default.cfm.

Maternal caffeine administration and cerebral oxygenation in near-term fetal sheep

The authors test the null hypothesis that maternal caffeine administration will not significantly alter fetal cerebral oxygenation. The authors measured fetal arterial blood gases, cortical tissue O(2) tension (tPO(2)), sagittal sinus blood gases, and laser Doppler cerebral blood flow in response to a 30-minute caffeine infusion (400 mg intravenously) into 7 near-term pregnant ewes, and they calculated fractional O(2) extraction and relative cerebral metabolic rate for O(2) (CMRO(2)). Following maternal caffeine infusion, both fetal cortical tPO(2) and sagittal sinus (HbO(2)) decreased significantly, from 10.7 +/- 0.9 to 6.8 +/- 1.1 Torr and from 46% +/- 2% to 37% +/- 6%, respectively. This was associated with significant 20% to 30% increases in fractional O(2) extraction and CMRO( 2). Fetal arterial blood gas values did not change significantly. In conclusion, maternal caffeine administration significantly decreases cerebral oxygenation without affecting systemic oxygenation in fetal sheep. The authors speculate that for a fetus that may be otherwise compromised, this increase in CMRO(2) with decreased cortical tPO(2) could present a problem.

Long-term effects of caffeine therapy for apnea of prematurity

BACKGROUND

Methylxanthine therapy is commonly used for apnea of prematurity but in the absence of adequate data on its efficacy and safety. It is uncertain whether methylxanthines have long-term effects on neurodevelopment and growth.

METHODS

We randomly assigned 2006 infants with birth weights of 500 to 1250 g to receive either caffeine or placebo until therapy for apnea of prematurity was no longer needed. The primary outcome was a composite of death, cerebral palsy, cognitive delay (defined as a Mental Development Index score of <85 on the Bayley Scales of Infant Development), deafness, or blindness at a corrected age of 18 to 21 months.

RESULTS

Of the 937 infants assigned to caffeine for whom adequate data on the primary outcome were available, 377 (40.2%) died or survived with a neurodevelopmental disability, as compared with 431 of the 932 infants (46.2%) assigned to placebo for whom adequate data on the primary outcome were available (odds ratio adjusted for center, 0.77; 95% confidence interval [CI], 0.64 to 0.93; P=0.008). Treatment with caffeine as compared with placebo reduced the incidence of cerebral palsy (4.4% vs. 7.3%; adjusted odds ratio, 0.58; 95% CI, 0.39 to 0.87; P=0.009) and of cognitive delay (33.8% vs. 38.3%; adjusted odds ratio, 0.81; 95% CI, 0.66 to 0.99; P=0.04). The rates of death, deafness, and blindness and the mean percentiles for height, weight, and head circumference at follow-up did not differ significantly between the two groups.

CONCLUSIONS

Caffeine therapy for apnea of prematurity improves the rate of survival without neurodevelopmental disability at 18 to 21 months in infants with very low birth weight. (ClinicalTrials.gov number, NCT00182312 [ClinicalTrials.gov].).

Correlation between plasma and urinary caffeine levels in preterm infants

BACKGROUND

We hypothesize that urine levels might be reliable to assess the therapeutic range of caffeine.

OBJECTIVES

We correlated plasma and urinary levels of caffeine in preterm infants treated with this drug for apnea of prematurity.

METHODS

Infants (n=56) were given a loading dose of caffeine citrate (10 mg/kg, per os) and 24 h later a maintenance dose (2 mg/kg, per os, once a day). Plasma and urinary levels of caffeine were determined 24 h after the loading dose (before administration of the maintenance dose) and then weekly.

RESULTS

Plasma and urinary levels correlate at all examined ages: 29 weeks (r=0.92, P<0.001), 30 weeks (r=0.97, P<0.001), 31 weeks (r=0.82, P<0.001), 32 weeks (r=0.92, P<0.001), 33 weeks (r=0.87, P<0.001), 34 weeks (r=0.81, P<0.001).

CONCLUSION

Urinary levels of caffeine might be a useful means to assess therapeutic ranges.

Utilisation du citrate de caféine pour le traitement des apnées idiopathiques du prématuré dans les équipes françaises de médecine néonatale

Caffeine citrate is commonly used for prophylaxis and treatment of apnea in preterm babies.

OBJECTIVE

To evaluate the use of caffeine citrate in french neonatal units.

MATERIALS AND METHODS

Postal survey in 100 neonatal units.

RESULTS

Answers were obtained from 81 units. Sixty-three units use systematic prophylactic treatment and the threshold of gestationnal age (weeks gestation) for this systematic treatment is 32 weeks. Caffeine citrate is administered as a loading dose of 20 mg/kg followed by a maintenance dose of 5 mg/kg in 95% of the units. Discontinuing the treatment occurs between 33 and 35 weeks in 37% of the units and between 35 and 37 weeks in 53%. Two third of neonatologits describe recurrent apnea beyond 37 weeks, with the need to continue treatment. Fourteen units sometimes discharge babies at home with ambulatory caffeine citrate treatment and discontinue treatment by 42 to 46 weeks'gestation. A mean duration of 5 days without apnea is required before discharge.

CONCLUSION

French teams respect "recommendations" concerning doses and duration without apnea before discharge. Indication of treatment, threshold for systematic treatment, duration of treatment and ambulatory treatment differ among teams.

Ampakines alleviate respiratory depression in rats

RATIONALE

There is a need for improved therapeutic interventions to treat both drug- and sleep-induced respiratory depression. Increased understanding of the neurochemical control of respiration will help identify a basis for advances. Activation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors positively modulates respiratory drive and rhythmogenesis in several brain regions including the pre-Bötzinger complex. Ampakines are a diverse group of small molecules that activate subsets of these receptors.

OBJECTIVE

We determined whether the ampakine CX546 would enhance respiratory drive and rhythmogenesis across various stages of development and whether this ampakine could counter opioid- and barbiturate-induced respiratory depression.

METHODS

Respiratory frequency and amplitude were measured in the following rat models: (1) perinatal in vitro brainstem-spinal cord, (2) neonatal in vitro medullary slice, (3) juvenile in situ perfused, working heart-brainstem preparation, and (4) newborn and adult in vivo.

RESULTS

Administration of CX546 stimulated baseline respiratory frequency in perinatal in vitro preparations but not in older animals (greater than Postnatal Day 0). Furthermore, pharmacologic depression of respiratory frequency and amplitude was countered at all ages studied by the administration of CX546 in vitro, in situ, and in vivo. Significantly, CX546 countered opioid-induced breathing depression in all preparations, without altering analgesia as assessed by measuring the time to foot withdrawal in response to a thermal stimulus.

CONCLUSIONS

CX546 effectively reverses opioid- and barbiturate-induced respiratory depression without reversing the analgesic response. These studies suggest that ampakines may be useful in preventing or reversing opioid-induced respiratory depression and identify the potential of ampakines for alleviating other forms of respiratory depression including sedative use and sleep apnea.

Effect of postnatal exposure to caffeine on the pattern of adenosine A1 receptor distribution in respiration-related nuclei of the rat brainstem

Caffeine, which belongs to the methylxantine family of compounds, is commonly ingested in a range of beverages such as coffee, tea, and cola drinks. It is also used therapeutically and is frequently employed in the treatment of respiratory disturbances in human neonates. The aim of the present work has been to examine the ontogeny of the adenosine A1 receptor system in the brainstem of the newborn rat following postnatal treatment with caffeine to mimic the therapeutic administration of caffeine to premature human infants. The effect of this postnatal exposure to caffeine on the gradual appearance of adenosine A1 receptors was analysed by determining immunohistochemically the distribution of the receptors. The main difference between control animals and animals exposed to caffeine was the transient increase (only at postnatal day 6) in the number of immunopositive neurons in two brainstem areas, the ventrolateral medulla and the rostral dorsolateral pons, in caffeine-treated rat pups, or more specifically, the parabrachial and Kölliker-Fuse nuclei, both of which are classically associated with respiratory control. With previous research highlighting the important role played by the rostral pons in respiratory modulation by the adenosine A1 receptor system, it is thus possible that postnatal exposure to caffeine modulates the ontogeny of the adenosine A1 receptor network. This could imply that the role of caffeine to decrease the incidence of neonatal respiratory disturbances may be due to the earlier than normal development of the adenosinergic system in the brain.

Caffeine therapy for apnea of prematurity

BACKGROUND

Methylxanthines reduce the frequency of apnea of prematurity and the need for mechanical ventilation during the first seven days of therapy. It is uncertain whether methylxanthines have other short- and long-term benefits or risks in infants with very low birth weight.

METHODS

We randomly assigned 2006 infants with birth weights of 500 to 1250 g during the first 10 days of life to receive either caffeine or placebo, until drug therapy for apnea of prematurity was no longer needed. We evaluated the short-term outcomes before the first discharge home.

RESULTS

Of 963 infants who were assigned to caffeine and who remained alive at a postmenstrual age of 36 weeks, 350 (36 percent) received supplemental oxygen, as did 447 of the 954 infants (47 percent) assigned to placebo (adjusted odds ratio, 0.63; 95 percent confidence interval, 0.52 to 0.76; P<0.001). Positive airway pressure was discontinued one week earlier in the infants assigned to caffeine (median postmenstrual age, 31.0 weeks; interquartile range, 29.4 to 33.0) than in the infants in the placebo group (median postmenstrual age, 32.0 weeks; interquartile range, 30.3 to 34.0; P<0.001). Caffeine reduced weight gain temporarily. The mean difference in weight gain between the group receiving caffeine and the group receiving placebo was greatest after two weeks (mean difference, -23 g; 95 percent confidence interval, -32 to -13; P<0.001). The rates of death, ultrasonographic signs of brain injury, and necrotizing enterocolitis did not differ significantly between the two groups.

CONCLUSIONS

Caffeine therapy for apnea of prematurity reduces the rate of bronchopulmonary dysplasia in infants with very low birth weight. (ClinicalTrials.gov number, NCT00182312.).