Apnea of prematurity: diagnosis, implications for care, and pharmacologic management

Caffeine Citrate for Apnea of Prematurity: A Prospective, Open-Label, Single-Arm Study in Chinese Neonates

Background: Caffeine citrate has been approved in China for the management of apnea of prematurity. This clinical trial was conducted as a condition of regulatory approval. The aim was to confirm the efficacy of caffeine citrate in the treatment of recurrent intermittent hypoxia and bradycardia in preterm newborns with primary apnea. Objectives: The primary outcome was the change from baseline in the number of apnea events after loading dose administration of caffeine citrate. Secondary efficacy outcomes included the change from baseline in apnea events after 2 and 4 weeks of maintenance doses. Methods: This was a multicenter, prospective longitudinal open-label, single-arm study. Neonates who had experienced at least four apnea events during a 24 h period received a loading dose of caffeine citrate 20 mg/kg; those who required additional maintenance doses received 5 mg/kg/day (titrated up to 10 mg/kg/day in case of insufficient response). The number of apnea events was recorded for 6-12 h prior to the loading dose (baseline), and for 12 h post-dose, following the loading dose and at Weeks 2 and 4 (during maintenance). Results: A total of 247 neonates received the loading dose, who had a significant reduction from baseline of 3.9 events (p < 0.001) in the mean number of apnea events. The subset of neonates who required maintenance doses also had significant reductions in the number of events at all visits (p < 0.001 for all). A total of 79.4% of participants had at least one adverse event, but only one non-serious and no serious events were considered related to treatment. Conclusions: In this large, prospective, open-label study, premature infants with a history of apnea who received caffeine citrate were significantly less likely to experience further apnea events.

Paediatric apnoeas are not related to a specific respiratory virus, and parental reports predict hospitalisation

Aim

The aim of this study was to determine the frequency of apnoeas in previously healthy young infants with acute respiratory tract infection (ARI) and correlate their occurrence with isolated micro‐organisms, clinical findings, disease severity and outcome.

Methods

We performed reverse transcriptase real‐time polymerase chain reaction (RT‐PCR) on the nasal wash specimens of a prospective cohort study of 582 children with ARI. Clinical data on a subgroup of 241 infants under three months of age, with and without apnoeas, were compared.

Results

Our study found that 19 (7.9%) of the 241 infants under three months old had a history of apnoeas: eight had a respiratory syncytial virus (RSV), five had a different virus than RSV and seven RT‐PCR results were negative. Infants with apnoeas were more likely to have cyanosis, had longer hospital stays and required extra oxygen for a longer period. Most patients with parental reported apnoeas also experienced apnoeas during hospitalisation.

Conclusion

This study observed apnoeas irrespective of the isolated micro‐organism, and we hypothesise that they were related to the pathophysiology of the respiratory infection and not to the micro‐organism itself. Parental reported apnoeas were a major warning sign and predicted that apnoeas would occur in hospital.

Gestational age at birth affects maturation of baroreflex control

OBJECTIVES

To assess the effect of prone sleeping, the major risk factor for sudden infant death syndrome, in the control of blood pressure (BP) in preterm infants born across a range of gestational ages.

STUDY DESIGN

Daytime polysomnography was performed at 2-4 weeks, 2-3 months, and 5-6 months postterm age. The participants were 21 very preterm (mean gestation 29.4 ± 0.3 weeks), 14 preterm (mean gestation 33.1 ± 0.3 weeks), and 17 term (mean gestation 40.1 ± 0.3 weeks). BP was measured via a Finometer cuff (Finapres Medical Systems, Amsterdam, The Netherlands) placed around the wrist. Data were recorded both supine and prone. Baroreflex sensitivity (BRS) was calculated via cross-spectral analysis of spontaneous fluctuations in BP.

RESULTS

BRS was lower in the prone position in very preterm infants at 2-4 weeks in active sleep (P < .05). Maturation of BRS was delayed in very preterm compared with both preterm and term infants.

CONCLUSIONS

Maturation of BRS after term-equivalent age is altered in very preterm infants. Reduced BRS may result in an impaired ability of very preterm infants to respond to cardiovascular stress during infancy and may predispose them to cardiovascular disease later in life.

Use of methylxanthine therapies for the treatment and prevention of apnea of prematurity

Apnea of prematurity (AOP) is a common complication of preterm birth, which affects more than 80 % of neonates with a birth weight less than 1,000 g. Methylxanthine therapies, including caffeine and theophylline, are a mainstay in the treatment and prevention of AOP. Despite their frequent use, little is known about the long-term safety and efficacy of these medications. In this review, we systematically evaluated the literature on neonatal methylxanthine therapies and found that caffeine is associated with fewer adverse effects and a wider therapeutic window when compared with theophylline. When used as a therapeutic agent, larger doses of caffeine citrate have been shown to improve acute neonatal outcomes when administered promptly, although further studies are needed to assess the long-term neurological consequences associated with the use of large loading doses. In a secondary analysis of data obtained from a randomized controlled trial, the prophylactic use of caffeine was associated with substantial cost savings and improved clinical outcomes. However, there remains a paucity of well-controlled, randomized clinical trials that have examined the use of caffeine as a prophylactic agent, and further prospective trials are needed to determine if caffeine is a safe and effective prophylactic agent. Additionally, measuring plasma concentrations longitudinally as a marker of therapeutic efficacy and/or toxicity has not been shown to be clinically useful in neonates who are responsive to treatment and exhibit no signs or symptoms of toxicity. However, in cases where toxicity is of concern or for neonates with congenital or pathophysiologic process that may alter the pharmacokinetics of these drugs, therapeutic drug monitoring may be warranted to monitor for methylxanthine toxicity.

Effects of caffeine and/or nasal CPAP treatment on laryngeal chemoreflexes in preterm lambs

Current knowledge suggests that laryngeal chemoreflexes (LCR) are involved in the occurrence of certain neonatal apneas/bradycardias, especially in the preterm newborn. While caffeine and/or nasal continuous positive airway pressure (nCPAP) are the most frequent options used for treating apneas in preterm newborns, their effects on LCR-related apneas/bradycardias are virtually unknown. The aim of the present study was to test the hypothesis that caffeine and/or nCPAP decreases LCR-related cardiorespiratory inhibition in a preterm ovine model. Seven preterm lambs were born vaginally on gestational day 133 (normal gestation: 147 days) after intramuscular injections of betamethasone and mifepristone. Five days after birth, a chronic surgical instrumentation was performed to record states of alertness, electrocardiogram, systemic arterial pressure, and electromyographic activity of a laryngeal constrictor muscle, as well as to insert a transcutaneous supraglottal catheter. LCR were induced in quiet sleep under four conditions: 1) control (without caffeine or nCPAP); 2) nCPAP (5 cmH2O, without caffeine); 3) caffeine (10 mg/kg infused intravenously for 30 min, without nCPAP); and 4) nCPAP + caffeine. Our results showed that nCPAP consistently blunted LCR-related cardiorespiratory inhibition vs. control condition, contrary to caffeine whose overall effect was nonsignificant. In addition, nCPAP condition was characterized by a more consistent and rapid arousal after HCl injection. No significant differences were observed between all tested conditions with regard to swallowing and cough. It is concluded that nCPAP should be further assessed for its usefulness in treating neonatal apneas linked to LCR.

MR Imaging of the Newborn: a technical perspective

This article discusses neonatal magnetic resonance (MR) imaging and reviews equipment and procedures for MR-related transport, sedation, monitoring, and scanning. MR is gaining importance in the diagnosis and clinical management of critically ill, and often very low birth weight infants, so research is ongoing to make transport and examination safer and imaging more successful. Efforts are focused on integration of dedicated neonate MR scanners in neonatal intensive care units, improvements in incubator technology and handling, and more efficient use of scan/sedation time by choosing dedicated neonate coil arrays that improve the signal-to-noise-ratio and facilitate the choice of modern imaging techniques.

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.

The nursing care of the surgical neonate

In the last two decades, advancement in neonatal surgery, anesthesia, and intensive care have improved the outcome not only for neonates with complex surgical conditions but also for those preterm infants with combined medical and surgical issues. Infants with surgical problems may remain in the neonatal care setting for weeks or months, and providing ongoing nursing care can be challenging but rewarding. In this article, the authors outline the immediate preoperative management, stabilization, and subsequent postoperative nursing care of the surgical neonate.