Effect of caffeine on respiratory muscle strength and lung function in prematurely born, ventilated infants

Caffeine: The Story beyond Oxygen-Induced Lung and Brain Injury in Neonatal Animal Models-A Narrative Review

Caffeine is one of the most commonly used drugs in intensive care to stimulate the respiratory control mechanisms of very preterm infants. Respiratory instability, due to the degree of immaturity at birth, results in apnea of prematurity (AOP), hyperoxic, hypoxic, and intermittent hypoxic episodes. Oxidative stress cannot be avoided as a direct reaction and leads to neurological developmental deficits and even a higher prevalence of respiratory diseases in the further development of premature infants. Due to the proven antioxidant effect of caffeine in early use, largely protective effects on clinical outcomes can be observed. This is also impressively observed in experimental studies of caffeine application in oxidative stress-adapted rodent models of damage to the developing brain and lungs. However, caffeine shows undesirable effects outside these oxygen toxicity injury models. This review shows the effects of caffeine in hyperoxic, hypoxic/hypoxic-ischemic, and intermittent hypoxic rodent injury models, but also the negative effects on the rodent organism when caffeine is administered without exogenous oxidative stress. The narrative analysis of caffeine benefits in cerebral and pulmonary preterm infant models supports protective caffeine use but should be given critical consideration when considering caffeine treatment beyond the recommended corrected gestational age.

Temporal effects of caffeine on intrapulmonary shunt in preterm ventilated infants

OBJECTIVES

We hypothesized that caffeine would be associated with a transient reduction in the right-to-left shunt and VA/Q. We aimed to explore the temporal effects of caffeine on right-to-left shunt, ventilation perfusion ratio (VA/Q) and shift of the oxyhaemoglobin dissociation curve (ODC) in premature ventilated infants.

METHODS

Retrospective cohort study at a tertiary neonatal unit of infants born at less than 31 weeks of gestation that were mechanically ventilated on day three of life. The non-invasive method of the ODC was used to determine the right-to-left shunt, VA/Q and shift before and at 1, 4 and 20 h after a maintenance dose of caffeine citrate.

RESULTS

A total of 21 infants were included with a median (range) gestational age of 27 (23.7-30.7) weeks. The median shunt percentage was significantly reduced, compared to baseline at 1 h (8 (range: 7-9) % vs. 4 (range: 0-6) %, p=0.042) and 4 h post caffeine administration (8 (range: 7-9) % vs. 0 (range: 0-3) %, p=0.042), but the VA/Q and the right shift of the ODC did not differ significantly between these time points. At 20 h, there were no significant differences between these indices compared to baseline values.

CONCLUSIONS

Caffeine led to a transient decrease in intrapulmonary shunt from one to 4 h after administration and this may be due to its diuretic action.

Effects of caffeine on diaphragmatic activity in preterm infants

BACKGROUND

Caffeine is the first-choice drug for the treatment for apnea of prematurity (AOP) in preterm infants and it has been reported that it improves the diaphragm activity. The aim of this study was to evaluate by ultrasound possible changes in diaphragm contractility and motility induced by caffeine.

METHODS

We studied 26 preterm infants with gestational age ≤34 weeks treated with caffeine for the prevention or treatment of AOP. Diaphragmatic ultrasound was performed 15 min (T₀ ) before and 60 min (T₆₀ ) after the loading (20 mg/kg) or maintenance (5 mg/kg) dose of caffeine.

RESULTS

Diaphragmatic excursion (DE) and thickness at the end of inspiration (DT-in) and expiration (DT-ex), as well as peak velocity of the excursion at the end of inspiration (DT-in) and expiration (DT-ex) increased after administration of both loading and maintenance dose of caffeine.

CONCLUSIONS

Ultrasounds confirmed that caffeine improves the activity of diaphragm in preterm infants improving its thickness, amplitude of excursions, and contraction velocity. These results are consistent with the effectiveness of caffeine in treating AOP and decreasing the risk of failure of noninvasive respiratory support in preterm infants with respiratory distress syndrome (RDS).

Diet-associated vertically transferred metabolites and risk of asthma, allergy, eczema, and infections in early childhood

BACKGROUND

Evidence suggests maternal pregnancy dietary intake and nutrition in the early postnatal period to be of importance for the newborn child's health. However, studies investigating diet-related metabolites transferred from mother to child on disease risk in childhood are lacking. We sought to investigate the influence of vertically transferred metabolites on risk of atopic diseases and infections during preschool age.

METHODS

In the Danish population-based COPSAC2010 mother-child cohort, information on 10 diet-related vertically transferred metabolites from metabolomics profiles of dried blood spots (DBS) at age 2-3 days was analyzed in relation to the risk of childhood asthma, allergy, eczema, and infections using principal component and single metabolite analyses.

RESULTS

In 678 children with DBS measurements, a coffee-related metabolite profile reflected by principal component 1 was inversely associated with risk of asthma (odds ratio (95% CI) 0.78 (0.64; 0.95), p = .014) and eczema at age 6 years (0.79 (0.65; 0.97), p = .022). Furthermore, increasing stachydrine (fruit-related), 3-carboxy-4-methyl-5-propyl-2-furanpropanoate (fish-related), and ergothioneine (fruit-, green vegetables-, and fish-related) levels were all significantly associated with reduced risks of infections at age 0-3 years (p < .05).

CONCLUSION

This study demonstrates associations between pregnancy diet-related vertically transferred metabolites measured in children in early life and risk of atopic diseases and infections in childhood. The specific metabolites associated with a reduced disease risk in children may contribute to the characterization of a healthy nutritional profile in pregnancy using a metabolomics-based unbiased tool for predicting childhood health.

Precision caffeine therapy for apnea of prematurity and circadian rhythms: New possibilities open up

Caffeine is the globally consumed psychoactive substance and the drug of choice for the treatment of apnea of prematurity (AOP), but its therapeutic effects are highly variable among preterm infants. Many of the molecular underpinnings of the marked individual response have remained elusive yet. Interestingly, the significant association between Clock gene polymorphisms and the response to caffeine therapy offers an opportunity to advance our understanding of potential mechanistic pathways. In this review, we delineate the functions and mechanisms of human circadian rhythms. An up-to-date advance of the formation and ontogeny of human circadian rhythms during the perinatal period are concisely discussed. Specially, we summarize and discuss the characteristics of circadian rhythms in preterm infants. Second, we discuss the role of caffeine consumption on the circadian rhythms in animal models and human, especially in neonates and preterm infants. Finally, we postulate how circadian-based therapeutic initiatives could open new possibilities to promote precision caffeine therapy for the AOP management in preterm infants.

Caffeine and bronchopulmonary dysplasia: Clinical benefits and the mechanisms involved

Bronchopulmonary dysplasia (BPD) is a chronic respiratory disease that occurs during the neonatal period and is commonly associated with prematurity. This condition results in a severe economic burden on society and the families involved. Caffeine is used not only for the treatment of apnea in prematurity, but also for the prevention of BPD. There are multiple clinical benefits of caffeine treatment, including improved extubation success, a reduced duration of mechanical ventilation, improved lung function, and a reduction of patent ductus arteriosus requiring treatment. These clinical benefits of caffeine for the treatment of BPD are supported by both clinical trials and evidence from animal models. However, the mechanism by which caffeine protects against BPD remains unclear. Here, we review the clinical value of caffeine in the prevention of BPD and its potential mechanisms of action, including anti-inflammatory, antioxidant, antifibrotic, and antiapoptotic properties, the regulation of angiogenesis, and diuretic effects. Our aim is to provide a new theoretical basis for the clinical treatment of BPD.

Respiratory muscle function in the newborn: a narrative review

Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure-time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. IMPACT: Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

Caffeine as a Factor Influencing the Functioning of the Human Body-Friend or Foe?

Nowadays, caffeine is one of the most commonly consumed substances, which presents in many plants and products. It has both positive and negative effects on the human body, and its activity concerns a variety of systems including the central nervous system, immune system, digestive system, respiratory system, urinary tract, etc. These effects are dependent on quantity, the type of product in which caffeine is contained, and also on the individual differences among people (sex, age, diet etc.). The main aim of this review was to collect, present, and analyze the available information including the latest discoveries on the impact of caffeine on human health and the functioning of human body systems, taking into account the role of caffeine in individual disease entities. We present both the positive and negative sides of caffeine consumption and the healing properties of this purine alkaloid in diseases such as asthma, Parkinson's disease, and others, not forgetting about the negative effects of excess caffeine (e.g., in people with hypertension, children, adolescents, and the elderly). In summary, we can conclude, however, that caffeine has a multi-directional influence on various organs of the human body, and because of its anti-oxidative properties, it was, and still is, an interesting topic for research studies including those aimed at developing new therapeutic strategies.

Prediction of pharmacokinetic values of two various dosages of caffeine in premature neonates with apnea

OBJECTIVES

Despite extensive caffeine use in preterm infants, the pharmacokinetics (PKs) data are limited because of the studies are complicated to do in these patients. This research was investigated the PK profile of two various dosages of caffeine in premature neonates.

MATERIALS AND METHODS

The PK values of caffeine in premature neonates with Apnea were predicted by using all of computer-based simulation (Simcyp®), population-based PK, and modeling (P-Pharm®). We assayed the plasma levels of caffeine in two groups. The information was analyzed utilizing nonlinear mixed-effects modeling approach. The PK parameters were assessed simulating virtual clinical considers with subjects got 20 mg. kg-1 of caffeine in both groups, which was followed by a 5 mg. kg-1 once daily in Group 1 or 2.5 mg. kg-1 twice daily in Group 2. All statistical analysis was executed utilizing SSPS issue 19 and a P value of 0.05 was chosen significance.

RESULTS

In the present study, the means CL, volume of distribution, and T1/2 of caffeine in preterm infants were 0.0476 L. h-1, 1.1081 L, 16.2284 h, respectively. Whereas our simulated means by Simcyp were 0.090 L. h-1, 1.841 L, and 14.653 h in Group 1 and 16.223 h in Group 2, respectively.

CONCLUSIONS

There was overall good agreement between predicted and measured PK values in our study. This study provides an initial demonstration of Simcyp simulation advantage on anticipating of PK parameters.

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.

Childhood respiratory outcomes after neonatal caffeine therapy

Caffeine to prevent or treat apnea of prematurity in the newborn period is now standard of care for infants born very preterm. It has both short- and longer-term effects on respiratory health. In the short-term it reduces the duration of assisted ventilation and of oxygen therapy. It also reduces the rate of treatment for a patent ductus arteriosus, and of bronchopulmonary dysplasia. In the longer-term it improves expiratory airflow in childhood, and may have some benefits on respiratory health. Because it has not been used as a neonatal treatment for long enough, it is unknown if neonatal caffeine treatment has any effects on adult expiratory airflow, or on chronic obstructive pulmonary disease in later adult life.

Caffeine versus aminophylline in combination with oxygen therapy for apnea of prematurity: A retrospective cohort study

The present study was conducted to investigate the clinical significance of caffeine and aminophylline in the treatment of premature infants with apnea under varying conditions of oxygen (O2) delivery. The clinical data of 120 premature infants with apnea treated with oxygen therapy and either caffeine citrate (20 mg/kg/day; n=77) or aminophylline (10 mg/kg/day; n=43) were retrospectively examined. The therapeutic performance of the drugs after the completion of the treatment was evaluated primarily according to the risk of recurrent episodes of apnea, the changes in the duration and concentration of inhaled O2 and the incidence of complications. In contrast to aminophylline, caffeine treatment significantly reduced the duration of O2 inhalation and the inhaled O2 concentration in the infants treated with mechanical ventilation or O2 delivery devices (P<0.05). Treatment with caffeine also decreased the incidence of recurrent apnea events and complications in the investigated population (P<0.05 or P<0.01). Caffeine performs better than aminophylline in the treatment of premature infants with apnea under different conditions of O2 delivery. The therapeutic performance of caffeine is achieved primarily via improving the efficacy of supplemental O2 and reducing the incidence of complications.

Lung disease and pulmonary hypertension in the premature infant

The premature infant is born into the world unprepared to naturally thrive in a foreign environment. Lung development entails immense growth, structural remodeling and differentiation of specialized cells during the normal term perinatal and postnatal periods. Thus, the premature infant presents with a lung deficient for appropriate respiration. Disruption of lung development seen in bronchopulmonary dysplasia (BPD) and chronic lung disease (CLD) results in not only impaired airway growth but also a deficiency in the accompanying vasculature including the capillary system required for gas exchange. Deficient vascular area can lead to elevated pulmonary vascular resistance and the development of pulmonary hypertension (PH). Unlike PH seen in children and adults with pulmonary arterial hypertension (PAH), treatment with conventional pulmonary vasodilators can be limited in developmental lung disease-associated PH because there are fewer blood vessels to dilate. In this brief review, we highlight some of the knowledge on PH in the premature infant presented at the Proceedings of the 22^nd Annual Update on Pediatric and Congenital Cardiovascular Disease.

Prevention of Oxygen-Induced Inflammatory Lung Injury by Caffeine in Neonatal Rats

Background

Preterm birth implies an array of respiratory diseases including apnea of prematurity and bronchopulmonary dysplasia (BPD). Caffeine has been introduced to treat apneas but also appears to reduce rates of BPD. Oxygen is essential when treating preterm infants with respiratory problems but high oxygen exposure aggravates BPD. This experimental study is aimed at investigating the action of caffeine on inflammatory response and cell death in pulmonary tissue in a hyperoxia-based model of BPD in the newborn rat. Material/Methods. Lung injury was induced by hyperoxic exposure with 80% oxygen for three (P3) or five (P5) postnatal days with or without recovery in ambient air until postnatal day 15 (P15). Newborn Wistar rats were treated with PBS or caffeine (10 mg/kg) every two days beginning at the day of birth. The effects of caffeine on hyperoxic-induced pulmonary inflammatory response were examined 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

Treatment with caffeine significantly attenuated changes in hyperoxia-induced cell death and apoptosis-associated factors. There was a significant decrease in proinflammatory mediators and redox-sensitive transcription factor NFκB in the hyperoxia-exposed lung tissue of the caffeine-treated group compared to the nontreated group. Moreover, treatment with caffeine under hyperoxia modulated the transcription of the adenosine receptor (Adora)1. Caffeine induced pulmonary chemokine and cytokine transcription followed by immune cell infiltration of alveolar macrophages as well as increased adenosine receptor (Adora1, 2a, and 2b) expression.

Conclusions

The present study investigating the impact of caffeine on the inflammatory response, pulmonary cell degeneration and modulation of adenosine receptor expression, provides further evidence that caffeine acts as an antioxidative and anti-inflammatory drug for experimental oxygen-mediated lung injury. Experimental studies may broaden the understanding of therapeutic use of caffeine in modulating detrimental mechanisms involved in BPD development.

Electrical activity of the diaphragm following a loading dose of caffeine citrate in ventilated preterm infants

BACKGROUND

Administration of caffeine citrate can facilitate extubation. Our aim was to determine whether a loading dose of caffeine citrate given to ventilated, preterm infants affected the diaphragm electrical activity.

METHODS

Infants <34 weeks of gestational age were recruited if requiring mechanical ventilation and prescribed a loading dose of caffeine citrate. Surface electrodes recorded the electrical activity of the diaphragm (dEMG) before and after administration of intravenous caffeine citrate. The mean amplitude of the EMG (dEMG) trace and the mean area under the EMG curve (aEMGc) were calculated.

RESULTS

Thirty-two infants were assessed with a median gestational age of 29 (27-31) weeks. The dEMG amplitude increased, peaking at 25 min post administration (p = 0.006), and the increase in aEMGc (p = 0.004) peaked at 30 min; the differences were not significant after 60 min. At 20 min, there was an increase in minute volume (p = 0.034) and a reduction in the peak inspiratory pressure (p = 0.049).

CONCLUSIONS

We have demonstrated a transient increase in both electrical activity of the diaphragm and respiratory function following an intravenous loading dose of caffeine citrate.

[Safety and efficacy of caffeine use started at different time in preterm infants: a multicenter study in Jiangsu Province, China]

OBJECTIVE

To study the efficacy and safety of caffeine used in the early (≤72 hours after birth) and late (>72 hours after birth) stage in preterm infants with a gestational age of ≤31 weeks.

METHODS

A retrospective analysis was performed for 640 preterm infants (with a gestational age of ≤31 weeks) who were admitted to the neonatal intensive care unit of eight hospitals in Jiangsu Province, China. Of the 640 preterm infants, 510 were given caffeine in the early stage (≤72 hours after birth; early use group) and 130 were given caffeine in the late stage (>72 hours after birth; late use group). The clinical data were compared between the two groups.

RESULTS

There were no significant differences in birth weight, Apgar score, sex, gestational age, and age on admission between the two groups (P>0.05). Compared with the late use group, the early use group had a significantly younger age at the beginning and withdrawal of caffeine treatment (P<0.05) and a significantly shorter duration of caffeine treatment (P<0.05). There was no significant difference in respiratory support on admission between the two groups (P>0.05). Compared with the late use group, the early use group had significantly lower incidence rate of apnea (P<0.05) and significantly shorter oxygen supply time and length of hospital stay (P<0.05). There were no significant differences between the two groups in the incidence rates of neonatal intracranial hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, retinopathy of prematurity, and patent ductus arteriosus at discharge and NBNA score at the corrected gestational age of 40 weeks (P>0.05). However, significant differences were found in the incidence of bronchopulmonary dysplasia and the rate of home oxygen therapy, but there was no significant difference in the mortality rate between the two groups (P>0.05).

CONCLUSIONS

Early use of caffeine can shorten the duration of caffeine treatment, oxygen supply time, and length of hospital stay, with little adverse effect, in preterm infants with a gestational age of ≤31 weeks.

Impact of early caffeine therapy in preterm newborns on infant lung function

OBJECTIVE

To know the effect of caffeine therapy on infant lung function in preterm infants with a gestational age less than 31 weeks.

MATERIAL AND METHODS

Forced vital capacity (FVC), forced expiratory volume at 0.5 seconds (FEV_0.5 ), and forced expiratory flows were measured by raised volume rapid thoracoabdominal compression technique; functional residual capacity was measured by plethysmography (FRC_pleth ). Compliance of the respiratory system was measured by a single interruption technique (Crs). The Student t test was used to compare lung function measurements between the two groups: treated versus nontreated with caffeine. A multivariate analysis was carried out considering each and every lung function parameter (z-score) as the dependent variable; and gender, gestational age, birth weight (z-score), corrected age, invasive mechanical ventilation (yes/no), and bronchopulmonary dysplasia (BPD) diagnosis (yes/no) as independent ones. Additionally, stratified analyses by BPD diagnosis were performed.

RESULTS

The multivariate analysis showed significant higher z-scores of FVC and FEV_0.5 in preterm infants treated with caffeine (P = .004 and P = .024, respectively). This result only being significant in the group of non-BPD infants (P = .021 and P = .042), after stratifying by BPD diagnosis. Differences were not found in z-scores of FEV0.5/FVC, FEF75, FEF25-75, FRCpleth, nor Crs.

CONCLUSION

Lung function (FVC and FEV_0.5 ) is improved in infants born under 31 weeks of gestation when treated with caffeine. This improvement is driven by the group of infants who did not suffer from BPD. Overall, our results show that there is an early beneficial effect of caffeine treatment in infant lung function.

Targeting Endotypic Traits with Medications for the Pharmacological Treatment of Obstructive Sleep Apnea. A Review of the Current Literature

Obstructive sleep apnea (OSA) is a highly prevalent condition with few therapeutic options. To date there is no approved pharmacotherapy for this disorder, but several attempts have been made in the past and are currently ongoing to find one. The recent identification of multiple endotypes underlying this disorder has oriented the pharmacological research towards tailored therapies targeting specific pathophysiological traits that contribute differently to cause OSA in each patient. In this review we retrospectively analyze the literature on OSA pharmacotherapy dividing the medications tested on the basis of the four main endotypes: anatomy, upper airway muscle activity, arousal threshold and ventilatory instability (loop gain). We show how recently introduced drugs for weight loss that modify upper airway anatomy may play an important role in the management of OSA in the near future, and promising results have been obtained with drugs that increase upper airway muscle activity during sleep and reduce loop gain. The lack of a medication that can effectively increase the arousal threshold makes this strategy less encouraging, although recent studies have shown that the use of certain sedatives do not worsen OSA severity and could actually improve patients' sleep quality.

Effects of caffeine on inspiratory muscle function

Research suggests that caffeine can enhance measures of muscular strength in the upper and lower extremities, although the literature is somewhat equivocal. Little is known on whether or not caffeine will improve maximal inspiratory pressure (MIP), a surrogate measure of inspiratory muscle strength. The purpose of the study was to determine the effects of a moderate dose of caffeine on inspiratory muscle function. Fifteen (8 male, 7 female) healthy adults (mean ± SD: age = 24.3 ± 6.4 years; height = 1.75 ± 0.11 m; body mass = 78.8 ± 16.5 kg) volunteered to participate in the study which used a double-blind, placebo-controlled, cross-over design. During the initial visit, baseline data was collected and participants were familiarized with inspiratory muscle measurements. For the second and third visits, participants ingested either a 5 mg kg^-1 dose of caffeine (CAF) or placebo capsule (PL). After one hour, they completed at least 12 maximal inspiratory manoeuvres with 1 min rest between each attempt. MIP, maximal inspiratory peak pressure (PP), and maximal rate of pressure development (MRPD) were recorded. The CAF trial resulted in significantly higher MIP (154.7 ± 35.8 vs. 146.6 ± 37.6 cmH₂O; p = 0.02) and PP (165.8 ± 36.8 vs. 158.3 cmH₂O; p = 0.01) compared to the PL condition. No significant difference was observed in MRPD (p = 0.18). MIP and PP improved after ingestion of caffeine compared to the placebo condition. The findings from the study further establish caffeine's potential ergogenic benefit on measures of muscular strength.

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.

Caffeine: an evidence-based success story in VLBW pharmacotherapy

Apnea of prematurity (AOP) is a common and pervasive problem in very low birth weight infants. Methylxanthines were reported >40 years ago to be an effective therapy and, by the early 2000s, caffeine had become the preferred methylxanthine because of its wide therapeutic index, excellent bioavailability, and longer half-life. A clinical trial to address unresolved questions and toxicity concerns, completed in 2004, confirmed significant benefits of caffeine therapy, including shorter duration of intubation and respiratory support, reduced incidence of chronic lung disease, decreased need for treatment of patent ductus arteriosus, reduced severity of retinopathy of prematurity, and improved motor and visual function. Cohort studies have now further delineated the benefits of initiation of therapy before 3 days postnatal age, and of higher maintenance doses to achieve incremental beneficial effects. This review summarizes the pivotal and in particular the most recent studies that have established the safety and efficacy of caffeine therapy for AOP and other respiratory and neurodevelopmental outcomes. Caffeine has a very favorable benefit-to-risk ratio, and has become one of the most prescribed and cost-effective pharmacotherapies in the NICU.

Development and Characterization of Dapsone Cocrystal Prepared by Scalable Production Methods

In this study, the formation of caffeine/dapsone (CAF/DAP) cocrystals by scalable production methods, such as liquid-assisted grinding (LAG) and spray drying, was investigated in the context of the potential use of processed cocrystal powder for pulmonary delivery. A CAF/DAP cocrystal (1:1 M ratio) was successfully prepared by slow evaporation from both acetone and ethyl acetate. Acetone, ethyl acetate, and ethanol were all successfully used to prepare cocrystals by LAG and spray drying. The powders obtained were characterized by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), and Fourier transform infrared spectroscopy (FTIR). Laser diffraction analysis indicated a median particle size (D₅₀) for spray-dried powders prepared from acetone, ethanol, and ethyl acetate of 5.4 ± 0.7, 5.2 ± 0.1, and 5.1 ± 0.0 μm respectively, which are appropriate sizes for pulmonary delivery by means of a dry powder inhaler. The solubility of the CAF/DAP cocrystal in phosphate buffer pH 7.4, prepared by spray drying using acetone, was 506.5 ± 31.5 μg/mL, while pure crystalline DAP had a measured solubility of 217.1 ± 7.8 μg/mL. In vitro cytotoxicity studies using Calu-3 cells indicated that the cocrystals were not toxic at concentrations of 0.1 and of 1 mM of DAP, while an in vitro permeability study suggested caffeine may contribute to the permeation of DAP by hindering the efflux effect. The results obtained indicate that the CAF/DAP cocrystal, particularly when prepared by the spray drying method, represents a possible suitable approach for inhalation formulations with applications in pulmonary pathologies.

Does duration of caffeine therapy in preterm infants born ≤1250 g at birth influence neurodevelopmental (ND) outcomes at 3 years of age?

OBJECTIVE

To evaluate the effect of duration of caffeine use on long-term neurodevelopmental (ND) outcomes at 3 years corrected age (CA) in preterm infants with birthweights (BW) ≤ 1250 g.

DESIGN/METHODS

All surviving infants with BW ≤ 1250 g admitted to the Foothills Medical Center neonatal intensive care unit (NICU) from January 2002 to December 2009 who received the first dose of caffeine in the first week of life and were followed up at three years CA were included in the study. Demographics and follow-up outcomes were compared based on early cessation of caffeine ≤ 14 days (ECC), intermediate cessation of caffeine 15-30 days (ICC), and late cessation of caffeine >30 days (LCC). The primary outcome of ND impairment was present if a child had any one of the following: cerebral palsy, cognitive delay, visual impairment, or hearing impairment or deafness. Univariate and logistic regression analyses were performed.

RESULTS

Of the 508 eligible infants, 448 (88%) were seen at 3 years CA at follow-up. ECC (n = 139), ICC (n = 122) and LCC (n = 187) groups had a median (range) BW of 979 (560-1250), 1010 (530-1250), and 980 (520-1250) g (p = 0.524) and median (range) gestational age (GA) of 27 (23-33), 28 (24-33), and 27 (24-32) weeks, respectively (p = 0.034). In logistic regression models adjusting for GA, maternal smoking, and each neonatal risk factor separately (IVH, NEC, sepsis, blood transfusions, BPD, postnatal dexamethasone, SNAP-II, and ventilator days), none of the models showed a statistically significant association between caffeine duration and ND impairment.

CONCLUSION

The duration of caffeine use in premature infants in the NICU does not impact on long-term ND outcomes at 3 years CA.

[Preventive effect of caffeine on bronchopulmonary dysplasia in preterm infants]

With the increase in the rescue success rate of critically ill preterm infants and extremely preterm infants, the incidence rate of bronchopulmonary dysplasia (BPD) is increasing year by year. BPD has a high mortality rate and high possibility of sequelae, which greatly affects the quality of life of preterm infants and brings a heavy burden to their families, and so the treatment of BPD is of vital importance. At present, no consensus has been reached on the treatment measures for BPD. However, recent studies have shown that early application of caffeine can prevent BPD. With reference to the latest studies on the effect of caffeine in the prevention of BPD, this article reviews the mechanism of action of caffeine in reducing pulmonary inflammation, improving morphological abnormalities of lung injury, reducing oxidative stress injury, and improving pulmonary function.

Caffeine prevents bilirubin-induced cytotoxicity in cultured newborn rat astrocytes

OBJECTIVE

Unconjugated bilirubin (UCB) may cause neurotoxicity in preterm neonates due to immaturity of UGT1A1 leading to bilirubin accumulation in the brain. Caffeine used in the treatment of apnea of prematurity was reported to decrease mechanical ventilation requirement, the frequencies of bronchopulmonary dysplasia, patent ductus arteriosus, cerebral palsy and neurodevelopmental disorders in very low birth weight infants. However, the effect of caffeine on hyperbilirubinemia was not yet clarified.

METHODS

We used astrocyte cell cultures obtained from 2-day-old Wistar albino rats via modified Cole and de Vellis method. UCB concentration toxic to 50% of astrocytes, and caffeine concentration increasing cell viability 100% were used in experiments. While no medication was applied to the control group, UCB (50 μM) and caffeine (100 μM) were applied to the bilirubin and caffeine groups for 24 h. Prophylactic and therapeutic caffeine groups were treated with caffeine 4 h before and after UCB exposure. The effects of caffeine were investigated in rat astrocytes exposed to UCB in terms of cell viability, apoptosis, antioxidant defense, proinflammatory cytokines, and Toll-like receptor (TLR)s.

RESULTS

Compared to the control group, UCB increased apoptosis, malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, total nitrate/nitrite, and TLR4 levels, and decreased cell viability, catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) activities, glutathione, and TLR9 levels (for all p < .001). Conversely, prophylactic and therapeutic caffeine improved the detrimental effects of UCB.

CONCLUSIONS

Caffeine seems encouraging for the prevention and treatment of bilirubin neurotoxicity in rats by means of its antiapoptotic, antioxidant, anti-inflammatory, anti-nitrosative, and anti-TLR-4 properties.

Lung development, regeneration and plasticity: From disease physiopathology to drug design using induced pluripotent stem cells

Lungs have a complex structure composed of different cell types that form approximately 17 million airway branches of gas-delivering bronchioles connected to 500 million gas-exchanging alveoli. Airways and alveoli are lined by epithelial cells that display a low rate of turnover at steady-state, but can regenerate the epithelium in response to injuries. Here, we review the key points of lung development, homeostasis and epithelial cell plasticity in response to injury and disease, because this knowledge is required to develop new lung disease treatments. Of note, canonical signaling pathways that are essential for proper lung development during embryogenesis are also involved in the pathophysiology of most chronic airway diseases. Moreover, the perfect control of these interconnected pathways is needed for the successful differentiation of induced pluripotent stem cells (iPSC) into lung cells. Indeed, differentiation of iPSC into airway epithelium and alveoli is based on the use of biomimetics of normal embryonic and fetal lung development. In vitro iPSC-based models of lung diseases can help us to better understand the impaired lung repair capacity and to identify new therapeutic targets and new approaches, such as lung cell therapy.

Caffeine citrate - Is it a silver bullet in neonatology?

Caffeine citrate is one of the most prescribed drug in the present day NICU for apnea. Its efficacy, tolerability, wide therapeutic index and safety margin has made it the drug of choice among the methylxanthines. Its therapeutic uses in apnea of prematurity, mechanical ventilation, bronchopulmonary dysplasia has made it a "silver bullet" in neonatology. However, there are still controversies surrounding this drug. This review is aimed to update the reader about the basic pharmacology, current therapeutic uses, adverse effects, controversies as well as present and future research of caffeine.

Caffeine ameliorates hyperoxia-induced lung injury by protecting GCH1 function in neonatal rat pups

BackgroundBronchopulmonary dysplasia (BPD) is a major morbidity in premature infants, and impaired angiogenesis is considered a major contributor to BPD. Early caffeine treatment decreases the incidence of BPD; the mechanism remains incompletely understood.MethodsSprague-Dawley rat pups exposed to normoxia or hyperoxia since birth were treated daily with either 20 mg/kg caffeine or normal saline by an intraperitoneal injection from day 2 of life. The lungs were obtained for studies at days 10 and 21.ResultsHyperoxia impaired somatic growth and lung growth in the rat pups. The impaired lung growth during hyperoxia was associated with decreased levels of cyclic AMP (cAMP) and tetrahydrobiopterin (BH4) in the lungs. Early caffeine treatment increased cAMP levels in the lungs of hyperoxia-exposed pups. Caffeine also increased the levels of phosphorylated endothelial nitric oxide synthase (eNOS) at serine¹¹⁷⁷, total and serine⁵¹ phosphorylated GTP cyclohydrolase 1 (GCH1), and BH4 levels, with improved alveolar structure and angiogenesis in hyperoxia-exposed lungs. Reduced GCH1 levels in hyperoxia were due, in part, to increased degradation by the ubiquitin-proteasome system.ConclusionOur data support the notion that early caffeine treatment can protect immature lungs from hyperoxia-induced damage by improving eNOS activity through increased BH4 bioavailability.

The Role of Caffeine in Noninvasive Respiratory Support

Caffeine is one of the most commonly prescribed medications in preterm neonates and is widely used to treat or prevent apnea of prematurity. Caffeine therapy is safe, effectively decreases apnea, and improves short- and long-term outcomes in preterm infants. In this review, the authors summarize the role of caffeine therapy for preterm infants receiving noninvasive respiratory support. As caffeine is already widely used, recent data are summarized that may guide clinicians in optimizing the use of caffeine therapy, with a review of the timing of initiation, dose, and duration of therapy.

[Effect of early caffeine treatment on the need for respirator therapy in preterm infants with respiratory distress syndrome]

OBJECTIVE

To study the efficacy of early caffeine treatment in preterm infants with respiratory distress syndrome (RDS).

METHODS

A prospective controlled clinical trial was performed. A total of 59 preterm infants with RDS were enrolled and divided into a caffeine group (30 infants) and a control group (29 infants). Caffeine was administered in the caffeine group and control group at the same dosage at 12-24 hours after birth and before extubation respectively. The respirator parameters and the incidence rates of ventilator-associated pneumonia (VAP) and apnea were compared between the two groups.

RESULTS

Compared with the control group, the caffeine group had significantly lower peak inspiratory pressure, peak fraction of inspired oxygen, and incidence rate of VAP (p<0.05), as well as significantly shorter intubation time, NCPAP time, and total duration of oxygen supply (p<0.05). In addition, the caffeine group had a significantly longer time to first onset of apnea after extubation (p<0.05) and significantly fewer times of onset of apnea 1-2 days after extubation (p<0.01), as compared with the control group.

CONCLUSIONS

Early caffeine treatment can reduce the need for assisted ventilation in preterm infants with RDS, help with early extubation and ventilator weaning, reduce the oxygen time in the late stage, reduce the incidence of VAP, and prevent the development of apnea after extubation.

An Official American Thoracic Society/European Respiratory Society Workshop Report: Evaluation of Respiratory Mechanics and Function in the Pediatric and Neonatal Intensive Care Units

Ready access to physiologic measures, including respiratory mechanics, lung volumes, and ventilation/perfusion inhomogeneity, could optimize the clinical management of the critically ill pediatric or neonatal patient and minimize lung injury. There are many techniques for measuring respiratory function in infants and children but very limited information on the technical ease and applicability of these tests in the pediatric and neonatal intensive care unit (PICU, NICU) environments. This report summarizes the proceedings of a 2011 American Thoracic Society Workshop critically reviewing techniques available for ventilated and spontaneously breathing infants and children in the ICU. It outlines for each test how readily it is performed at the bedside and how it may impact patient management as well as indicating future areas of potential research collaboration. From expert panel discussions and literature reviews, we conclude that many of the techniques can aid in optimizing respiratory support in the PICU and NICU, quantifying the effect of therapeutic interventions, and guiding ventilator weaning and extubation. Most techniques now have commercially available equipment for the PICU and NICU, and many can generate continuous data points to help with ventilator weaning and other interventions. Technical and validation studies in the PICU and NICU are published for the majority of techniques; some have been used as outcome measures in clinical trials, but few have been assessed specifically for their ability to improve clinical outcomes. Although they show considerable promise, these techniques still require further study in the PICU and NICU together with increased availability of commercial equipment before wider incorporation into daily clinical practice.

Caffeine Exposure and Risk of Acute Kidney Injury in a Retrospective Cohort of Very Low Birth Weight Neonates

OBJECTIVE

To evaluate the association between caffeine exposure and acute kidney injury (AKI) in very low birth weight (VLBW; ≤1500 g) neonates.

STUDY DESIGN

We retrospectively reviewed a cohort of 140 VLBW neonates consecutively admitted to the University of Virginia's neonatal intensive care unit from March 2011 to June 2012, excluding only those admitted >2 days of age or who died at <2 days after birth. We separately analyzed a subgroup of 44 neonates who received prolonged invasive respiratory support (mechanical ventilation for first 7 days after birth). The exposure of interest was caffeine exposure in the first week after birth. The primary outcome was AKI within the first 10 days after birth according to the Kidney Disease: Improving Global Outcomes system, modified to include only serum creatinine.

RESULTS

Caffeine exposure occurred in 72.1% of all patients and 54.5% of those who received prolonged invasive respiratory support. AKI occurred less frequently in neonates who received caffeine (all patients: 17.8% vs 43.6%; P = .002; prolonged invasive respiratory support: 29.2% vs 75.0%; P = .002). Caffeine exposure was associated with decreased odds for AKI in logistic regression models adjusted for sex, birth weight, gestational age, small for gestational age status, illness severity on admission, and receipt of indomethacin, invasive ventilation, dopamine, aminoglycosides, and vancomycin (all patients: OR 0.22; 95% CI 0.07-0.75, P = .02; prolonged invasive respiratory support subgroup: OR 0.06; 95% CI 0.01-0.57, P = .02).

CONCLUSIONS

In a cohort of VLBW neonates, those exposed to caffeine were less likely to experience AKI.

Caffeine Prevents Hyperoxia-Induced Functional and Structural Lung Damage in Preterm Rabbits

BACKGROUND

Caffeine is a commonly used drug for apnea of prematurity. It may, however, also have a beneficial effect on bronchopulmonary dysplasia (BPD), which is the most common complication of extreme preterm birth.

OBJECTIVES

To study the inflammatory, structural and functional effects of caffeine in an animal model of BPD.

METHODS

Preterm New Zealand-Dendermonde rabbits (gestational day 28; term 31) were randomized to three groups: normoxia-placebo (N-P), hyperoxia-placebo (H-P) and hyperoxia-caffeine (H-C). Lung function was assessed on postnatal day 5, along with airway morphometry, vascular morphometry and a score observing airway inflammation.

RESULTS

Caffeine improved lung function by increasing lung volume [mean displaced volume N-P: 40.1 ± 6 ml/kg, H-P: 27.8 ± 8 ml/kg and H-C: 34.4 ± 7 ml/kg (p < 0.05); total lung capacity: N-P: 1.17 ± 0.1 ml, H-P: 0.67 ± 0.1 ml and H-C: 1.1 ± 0.1 ml (p < 0.05)], decreasing tissue damping [N-P: 2.7 ± 0.3 cm H2O/ml, H-P: 4.6 ± 0.6 cm H2O/ml and H-C: 3.2 ± 0.4 cm H2O/ml (p < 0.05)], elastance [N-P: 9.3 ± 2.4 cm H2O/ml, H-P: 19.2 ± 7.4 cm H2O/ml and H-C: 10.7 ± 2 cm H2O/ml (p < 0.05)] and compliance [N-P: 0.06 ± 0.01 cm H2O/ml, H-P: 0.054 ± 0.01 cm H2O/ml and H-C: 0.07 ± 0.013 cm H2O/ml (p < 0.05)]. Caffeine also improved histology by decreasing alveolar size [linear intercepts; N-P: 83.6 ± 1.7, H-P: 82.9 ± 1.6 and H-C: 67.3 ± 1.4 (p < 0.05)], increasing radial alveolar count (N-P: 6.6 ± 0.5, H-P: 5.7 ± 0.6 and H-C: 7.05 ± 0.5) and decreasing the acute inflammation score [N-P: 0.3 ± 0.1, H-P: 0.5 ± 0.1 and H-C: 0.4 ± 0.1 (p < 0.05)].

CONCLUSION

In preterm rabbits, caffeine reduces the functional, architectural and inflammatory pulmonary changes induced by hyperoxia in the lung.

Evidence-Based Pharmacologic Therapies for Prevention of Bronchopulmonary Dysplasia: Application of the Grading of Recommendations Assessment, Development, and Evaluation Methodology

Bronchopulmonary dysplasia (BPD) is the most common chronic complication of extreme preterm birth. The authors applied the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology to pharmacologic therapies found to prevent BPD. Caffeine and vitamin A are the only medications shown in high-quality studies to prevent BPD without the risk of clinically important adverse effects. Dexamethasone is effective for the prevention of BPD; but for many infants, the increased risks of hypertrophic cardiomyopathy, gastrointestinal perforation, and cerebral palsy outweigh this benefit. Several medications are currently under investigation for the prevention of BPD, but few are novel agents.

Early Caffeine Use in Very Low Birth Weight Infants and Neonatal Outcomes: A Systematic Review and Meta-Analysis

The use of caffeine citrate for treatment of apnea in very low birth weight infants showed short-term and long-term benefits. A systematic review and meta-analysis of the literature was undertaken to document the effect providing caffeine early (0-2 days of life) compared to providing caffeine late (≥3 days of life) in very low birth weight infants on several neonatal outcomes, including bronchopulmonary dysplasia (BPD). We searched MEDLINE, the EMBASE database, the Cochrane Library, and KoreaMed for this meta-analysis. The quality of the included studies was assessed using the Newcastle-Ottawa Scale and Jadad's scale. Studies were included if they examined the effect of the early use of caffeine compared with the late use of caffeine. Two reviewers screened the candidate articles and extracted the data from the full-text of all of the included studies. We included a total of 59,136 participants (range 58,997-59,136; variable in one study) from a total of 5 studies. The risk of death (odds ratio [OR], 0.902; 95% confidence interval [CI], 0.828 to 0.983; P=0.019), bronchopulmonary dysplasia (BPD) (OR, 0.507; 95% CI, 0.396 to 0.648; P<0.001), and BPD or death (OR, 0.526; 95% CI, 0.384 to 0.719; P<0.001) were lower in the early caffeine group. Early caffeine use was not associated with a risk of necrotizing enterocolitis (NEC) and NEC requiring surgery. This meta-analysis suggests that early caffeine use has beneficial effects on neonatal outcomes, including mortality and BPD, without increasing the risk of NEC.

Caffeine therapy in preterm infants

Caffeine is the most commonly used medication for treatment of apnea of prematurity. Its effect has been well established in reducing the frequency of apnea, intermittent hypoxemia, and extubation failure in mechanically ventilated preterm infants. Evidence for additional short-term benefits on reducing the incidence of bronchopulmonary dysplasia and patent ductus arteriosus has also been suggested. Controversies exist among various neonatal intensive care units in terms of drug efficacy compared to other methylxanthines, dosage regimen, time of initiation, duration of therapy, drug safety and value of therapeutic drug monitoring. In the current review, we will summarize the available evidence for the best practice in using caffeine therapy in preterm infants.

The effect of caffeine citrate on neural breathing pattern in preterm infants

BACKGROUND

Caffeine citrate is widely used to prevent and treat prematurity-associated apnea.

AIMS

The aim of this study was to characterize the effect of caffeine citrate on the neural control of breathing, especially central apnea, in premature infants.

STUDY DESIGN

Preterm infants were evaluated for 30min before and 30min after caffeine citrate loading (20mg/kg). A feeding tube including miniaturized sensors was used to measure the diaphragm electrical activity (Edi) waveform. Central apnea was defined as any period where the Edi waveform was flat for >5s.

SUBJECTS

Seventeen preterm infants with a mean age of three days and mean birth weight of 900 grams were evaluated.

OUTCOME MEASURES

In addition to central apnea, several parameters including neural inspiratory time, neural respiratory rate, peak Edi, delta inspiratory change in Edi (phasic Edi) and minimum Edi on exhalation were measured.

RESULTS

The majority of the apnea were short (5 to 10s) and the number of apnea correlated with birth weight (p=0.039). Caffeine citrate reduced significantly the number of 5-to-10-second-long central apnea during the 30-minute periods (12±11 to 7±7; p=0.02). Caffeine citrate increased both peak and phasic Edi leading to a significant increase in the diaphragm energy expenditure.

CONCLUSIONS

Edi signal can be reliably measured and processed to study changes in premature infants' neural breathing. The beneficial effect of caffeine citrate on the reduction of the number of apnea is mediated through stimulated neural breathing increasing the diaphragm energy expenditure.

High versus low-dose caffeine for apnea of prematurity: a randomized controlled trial

The optimum caffeine dose in preterm infants has not been well investigated. We aimed to compare the efficacy and safety of high versus low-dose caffeine citrate on apnea of prematurity (AOP) and successful extubation of preterm infants from mechanical ventilation. We compared high-dose (loading 40 mg/kg/day and maintenance of 20 mg/kg/day) versus low-dose (loading 20 mg/kg/day and maintenance of 10 mg/kg/day) caffeine citrate in preterm infants <32 weeks gestation, presented with AOP within the first 10 days of life. A total of 120 neonates (60 in each group) were enrolled. High-dose caffeine was associated with a significant reduction in extubation failure in mechanically ventilated preterm infants (p<0.05), the frequency of apnea (p<0.001), and days of documented apnea (p<0.001). High-dose caffeine was associated with significant increase in episodes of tachycardia (p<0.05) without a significant impact on physician decision to withhold caffeine.

CONCLUSION

The use of higher, than current standard, dose of caffeine may decrease the chance of extubation failure in mechanically ventilated preterm infants and frequency of AOP without significant side effects.

WHAT IS KNOWN

• Caffeine therapy for treatment of apnea of prematurity has been well established over the past few years. The optimal loading and maintenance dose of caffeine in preterm infants is not well-studied. What is New: • This double blind randomized controlled trial demonstrated that using a higher, than current standard, loading and maintenance doses of caffeine for treatment of apnea in preterm infants is well tolerated and significantly decrease the frequency of apnea.

Serum caffeine concentrations and short-term outcomes in premature infants of ⩽29 weeks of gestation

OBJECTIVE

Caffeine is effective in the treatment of apnea of prematurity but it is not well known if the therapeutic concentration of the drug has an impact on other neonatal outcomes such as chronic lung disease (CLD). The aim of this study was to determine if there is an association between caffeine concentrations and the incidence of CLD in premature infants of ⩽29 weeks of gestation.

STUDY DESIGN

A retrospective chart review of all the infants born ⩽29 weeks of gestation from 2007 to 2011, who survived until discharge or 36 weeks postmenstrual age, was conducted. Caffeine concentrations were obtained weekly on infants getting the drug. Average caffeine concentrations (ACCs) were determined for the duration of caffeine therapy and correlated with CLD, length of stay (LOS), oxygen at discharge (OD), duration of ventilation (DV) and total charges for hospitalization for each patient.

RESULTS

Of the 222 eligible infants, 198 met the inclusion criteria. ACC for infants without CLD was 17.0±3.8 μg ml(-1) compared with infants with CLD 14.3±6.1 μg ml(-1) (P<0.001). Infants receiving high ACC (>14.5 μg ml(-1)) had lower incidence of patent ductus arteriosus, lesser number of days on ventilator and oxygen, lesser need for diuretics, lower incidence of CLD, were more likely to go home without supplemental OD and had lower LOS and lower total hospital charges (all differences were significant P<0.05) Multiple logistic regression modeling after adjusting for confounding variables indicated that higher caffeine concentrations were significantly associated with decrease in CLD. Receiver operating curve analysis confirmed a significant predictive ability of caffeine concentration for CLD with a cutoff concentration of 14.5 μg ml(-1) (sensitivity of 42.6 and specificity of 86.8). The AUC (area under the curve) for the prediction of CLD was 0.632 (95% confidence interval 0.56-0.69, P=0.009).

CONCLUSIONS

Caffeine concentrations >14.5 μg ml(-1) were strongly correlated with reduced CLD in infants born at ⩽29 weeks of gestation. Higher caffeine concentrations were associated with decreased total hospital charges, DV, OD and LOS. Additional randomized trials are needed to confirm these findings, to identify ideal serum concentrations and determine possible long-term neurologic benefits.

Discontinuing caffeine in preterm infants at 33-35 weeks corrected gestational age: Failure rate and predictive factors

OBJECTIVE

To examine the success rate of our current practice of discontinuing caffeine at 33 0/7-35 6/7 weeks post menstrual age (PMA), as well as factors that predict the success or failure of discontinuation.

STUDY DESIGN

A retrospective chart review of infants born before 34 weeks gestational age between 2006-2012. Data collected included demographics, and other comorbidities mainly complications of prematurity.

RESULTS

647 treated infants had caffeine discontinued at 33-35 PMA before discharge or transfer. 64 (10%) infants failed discontinuation and had caffeine restarted. Most (77%) of those who failed started having monitor alarms within 7 days of discontinuation. BPD and Hispanic ethnicity were predictive of weaning failure (p < 0.05).

CONCLUSION

Caffeine can be discontinued at 33-35 weeks PMA with a failure rate of 10%. BPD and Hispanic ethnicity are predictive of failure. It is generally safe to discharge infants seven days after the caffeine was discontinued if no significant monitor events occur during that time.

Effect of caffeine on preterm infants' cerebral cortical activity: an observational study

OBJECTIVE

Our first aim was to investigate the effects of caffeine on preterm infants' respiratory functions and brain cortical activity (conventional and amplitude-integrated electroencephalography (cEEG and aEEG)). Secondary aim was to study its long-term effects on respiratory system and electroencephalographic maturation by 36 weeks post-menstrual age.

METHODS

Prospective observational study on 33 consecutively admitted preterm infants less than 34-weeks-gestation. cEEG and aEEG, cardiopulmonary and sleep state were recorded in 20 preterm infants, before, during and 2-hours after intravenous (IV) caffeine (caffeine Group), and for 13 preterms (control group). Both groups were subjected to assessment of cerebral cortical maturation by cEEG and aEEG at 36-weeks post-menstrual age as an outcome measure.

RESULTS

IV caffeine administration significantly increased heart rate (p = 0.000), mean arterial blood pressure (p = 0.000), capillary oxygen saturation (p = 0.003), arousability (p = 0.000) and aEEG continuity (p = 0.002) after half an hour. No clinical seizures were recorded and non-significant difference was found in electrographic seizures activity in cEEG. At 36-weeks post-conceptional age, NICU stay was significantly longer in controls (p = 0.022). aEEG score was significantly higher in caffeine group than the control group, (p = 0.000).

CONCLUSIONS

Caffeine increases preterm infants' cerebral cortical activity during infusion and results in cerebral cortical maturation at 36weeks, without increase in seizure activity.

Caffeine citrate: when and for how long. A literature review

The efficacy of caffeine in an episode of Apnoea of Prematurity (AOP) has been known for over thirty years. Its use over long periods of time has not only found it to be manageable within the field of neonatology, but it has also been found to have other favourable actions, such as reducing the incidence of extubation failure, preventing Bronchopulmonary Dysplasia (BPD), reducing the need for Patent Ductus Arteriosus treatment and the beneficial effect it has on Retinopathy of Prematurity. Recent in vitro trials have highlighted the neuroprotective role that caffeine plays, which has already partly been observed from in vivo trials. Just recently, caffeine citrate has become a "label" drug and it would be beneficial if more studies could confirm the more significant effects it has on the more severe conditions of prematurity.

Predictors of bronchopulmonary dysplasia

Although significant advances in respiratory care have been made in neonatal medicine, bronchopulmonary dysplasia (BPD) remains the most common serious pulmonary morbidity in premature infants. The development of BPD is the result of the complex interactions between multiple perinatal and postnatal factors. Early identification of infants at the most risk of developing BPD through the use of estimators and models may allow a targeted approach at reducing BPD in the future.