Methylxanthine for the prevention and treatment of apnea in preterm infants.

BACKGROUND: Very preterm infants often require respiratory support and are therefore exposed to an increased risk of chronic lung disease and later neurodevelopmental disability. Although methylxanthines are widely used to prevent and treat apnea associated with prematurity and to facilitate extubation, there is uncertainty about the benefits and harms of different types of methylxanthines. OBJECTIVES: To assess the effects of methylxanthines on the incidence of apnea, death, neurodevelopmental disability, and other longer-term outcomes in preterm infants (1) at risk for or with apnea, or (2) undergoing extubation. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, two other databases, and three trial registers (November 2022). SELECTION CRITERIA: We included randomized trials in preterm infants, in which methylxanthines (aminophylline, caffeine, or theophylline) were compared to placebo or no treatment for any indication (i.e. prevention of apnea, treatment of apnea, or prevention of re-intubation). DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods and GRADE to assess the certainty of evidence. MAIN RESULTS: We included 18 studies (2705 infants), evaluating the use of methylxanthine in preterm infants for: any indication (one study); prevention of apnea (six studies); treatment of apnea (five studies); and to prevent re-intubation (six studies). Death or major neurodevelopmental disability (DMND) at 18 to 24 months. Only the Caffeine for Apnea of Prematurity (CAP) study (enrolling 2006 infants) reported on this outcome. Overall, caffeine probably reduced the risk of DMND in preterm infants treated with caffeine for any indication (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.78 to 0.97; risk difference (RD) -0.06, 95% CI -0.10 to -0.02; number needed to treat for an additional beneficial outcome (NNTB) 16, 95% CI 10 to 50; 1 study, 1869 infants; moderate-certainty evidence). No other trials reported DMND. Results from the CAP trial regarding DMND at 18 to 24 months are less precise when analyzed based on treatment indication. Caffeine probably results in little or no difference in DMND in infants treated for prevention of apnea (RR 1.00, 95% CI 0.80 to 1.24; RD -0.00, 95% CI -0.10 to 0.09; 1 study, 423 infants; moderate-certainty evidence) and probably results in a slight reduction in DMND in infants treated for apnea of prematurity (RR 0.85, 95% CI 0.71 to 1.01; RD -0.06, 95% CI -0.13 to 0.00; NNTB 16, 95% CI 7 to > 1000; 1 study, 767 infants; moderate-certainty evidence) or to prevent re-intubation (RR 0.85, 95% CI 0.73 to 0.99; RD -0.08, 95% CI -0.15 to -0.00; NNTB 12, 95% CI 6 to >1000; 1 study, 676 infants; moderate-certainty evidence). Death. In the overall analysis of any methylxanthine treatment for any indication, methylxanthine used for any indication probably results in little or no difference in death at hospital discharge (RR 0.99, 95% CI 0.71 to 1.37; I2 = 0%; RD -0.00, 95% CI -0.02 to 0.02; I2 = 5%; 7 studies, 2289 infants; moderate-certainty evidence). Major neurodevelopmental disability at 18 to 24 months. In the CAP trial, caffeine probably reduced the risk of major neurodevelopmental disability at 18 to 24 months (RR 0.85, 95% CI 0.76 to 0.96; RD -0.06, 95% CI -0.10 to -0.02; NNTB 16, 95% CI 10 to 50; 1 study, 1869 infants; moderate-certainty evidence), including a reduction in the risk of cerebral palsy or gross motor disability (RR 0.60, 95% CI 0.41 to 0.88; RD -0.03, 95% CI -0.05 to -0.01; NNTB 33, 95% CI 20 to 100; 1 study, 1810 infants; moderate-certainty evidence) and a marginal reduction in the risk of developmental delay (RR 0.88, 95% CI 0.78 to 1.00; RD -0.05, 95% CI -0.09 to -0.00; NNTB 20, 95% CI 11 to > 1000; 1 study, 1725 infants; moderate-certainty evidence). Any apneic episodes, failed apnea reduction after two to seven days (< 50% reduction in apnea) (for infants treated with apnea), and need for positive-pressure ventilation after institution of treatment. Methylxanthine used for any indication probably reduces the occurrence of any apneic episodes (RR 0.31, 95% CI 0.18 to 0.52; I2 = 47%; RD -0.38, 95% CI -0.51 to -0.25; I2 = 49%; NNTB 3, 95% CI 2 to 4; 4 studies, 167 infants; moderate-certainty evidence), failed apnea reduction after two to seven days (RR 0.48, 95% CI 0.33 to 0.70; I2 = 0%; RD -0.31, 95% CI -0.44 to -0.17; I2 = 53%; NNTB 3, 95% CI 2 to 6; 4 studies, 174 infants; moderate-certainty evidence), and may reduce receipt of positive-pressure ventilation after institution of treatment (RR 0.61, 95% CI 0.39 to 0.96; I2 = 0%; RD -0.06, 95% CI -0.11 to -0.01; I2 = 49%; NNTB 16, 95% CI 9 to 100; 9 studies, 373 infants; low-certainty evidence). Chronic lung disease. Methylxanthine used for any indication reduces chronic lung disease (defined as the use of supplemental oxygen at 36 weeks' postmenstrual age) (RR 0.77, 95% CI 0.69 to 0.85; I2 = 0%; RD -0.10, 95% CI -0.14 to -0.06; I2 = 18%; NNTB 10, 95% CI 7 to 16; 4 studies, 2142 infants; high-certainty evidence). Failure to extubate or the need for re-intubation within one week after initiation of therapy. Methylxanthine used for the prevention of re-intubation probably results in a large reduction in failed extubation compared with no treatment (RR 0.48, 95% CI 0.32 to 0.71; I2 = 0%; RD -0.27, 95% CI -0.39 to -0.15; I2 = 69%; NNTB 4, 95% CI 2 to 6; 6 studies, 197 infants; moderate-certainty evidence). AUTHORS' CONCLUSIONS: Caffeine probably reduces the risk of death, major neurodevelopmental disability at 18 to 24 months, and the composite outcome DMND at 18 to 24 months. Administration of any methylxanthine to preterm infants for any indication probably leads to a reduction in the risk of any apneic episodes, failed apnea reduction after two to seven days, cerebral palsy, developmental delay, and may reduce receipt of positive-pressure ventilation after institution of treatment. Methylxanthine used for any indication reduces chronic lung disease (defined as the use of supplemental oxygen at 36 weeks' postmenstrual age).

Doxapram for the prevention and treatment of apnea in preterm infants.

BACKGROUND: Apnea of prematurity is a common problem in preterm infants that may have significant consequences on their development. Methylxanthines (aminophylline, theophylline, and caffeine) are effective in the treatment of apnea of prematurity. Doxapram is used as a respiratory stimulant in cases refractory to the methylxanthine treatment. OBJECTIVES: To evaluate the benefits and harms of doxapram administration on the incidence of apnea and other short-term and longer-term clinical outcomes in preterm infants. SEARCH METHODS: We used standard, extensive Cochrane search methods. The latest search date was March 2023. SELECTION CRITERIA: We included randomized controlled trials (RCTs) assessing the role of doxapram in prevention and treatment of apnea of prematurity and prevention of reintubation in preterm infants (less than 37 weeks' gestation). We included studies comparing doxapram with either placebo or methylxanthines as a control group, or when doxapram was used as an adjunct to methylxanthines and compared to methylxanthines alone as a control group. We included studies of doxapram at any dose and route. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were clinical apnea, need for positive pressure ventilation after initiation of treatment, failed apnea reduction after two to seven days, and failed extubation (defined as unable to wean from invasive intermittent positive pressure ventilation [IPPV] and extubate or reintubation for IPPV within one week). We used GRADE to assess the certainty of evidence for each outcome. MAIN RESULTS: We included eight RCTs enrolling 248 infants. Seven studies (214 participants) provided data for meta-analysis. Five studied doxapram for treatment of apnea in preterm infants. Three studied doxapram to prevent reintubation in preterm infants. None studied doxapram in preventing apnea in preterm infants. All studies administered doxapram intravenously as continuous infusions. Two studies used doxapram as an adjunct to aminophylline compared to aminophylline alone and one study as an adjunct to caffeine compared to caffeine alone. When used to treat apnea, compared to no treatment, doxapram may result in a slight reduction in failed apnea reduction (risk ratio [RR] 0.45, 95% confidence interval [CI] 0.20 to 1.05; 1 study, 21 participants; low-certainty evidence). The evidence is very uncertain about the effect of doxapram on need for positive pressure ventilation after initiation of treatment (RR 0.31, 95% CI 0.01 to 6.74; 1 study, 21 participants; very low-certainty evidence). Doxapram may result in little to no difference in side effects causing cessation of therapy (0 events in both groups; risk difference [RD] 0.00, 95% CI -0.17 to 0.17; 1 study, 21 participants; low-certainty evidence). Compared to alternative treatment, the evidence is very uncertain about the effect of doxapram on failed apnea reduction (RR 1.35, 95% CI 0.53 to 3.45; 4 studies, 84 participants; very low-certainty evidence). The evidence is very uncertain about the effect of doxapram on need for positive pressure ventilation after initiation of treatment (RR 2.40, 95% CI 0.11 to 51.32; 2 studies, 37 participants; very-low certainty evidence; note 1 study recorded 0 events in both groups. Thus, the RR and CIs were calculated from 1 study rather than 2). Doxapram may result in little to no difference in side effects causing cessation of therapy (0 events in all groups; RD 0.00, 95% CI -0.15 to 0.15; 37 participants; 2 studies; low-certainty evidence). As adjunct therapy to methylxanthine, the evidence is very uncertain about the effect of doxapram on failed apnea reduction after two to seven days (RR 0.08, 95% CI 0.01 to 1.17; 1 study, 10 participants; very low-certainty evidence). No studies reported on clinical apnea, chronic lung disease at 36 weeks' postmenstrual age (PMA), death at any time during initial hospitalization, long-term neurodevelopmental outcomes in the three comparisons, and need for positive pressure ventilation and side effects when used as adjunct therapy to methylxanthine. In studies to prevent reintubation, when compared to alternative treatment, the evidence is very uncertain about the effect of doxapram on failed extubation (RR 0.43, 95% CI 0.10 to 1.83; 1 study, 25 participants; very low-certainty evidence). As adjunct therapy to methylxanthine, doxapram may result in a slight reduction in 'clinical apnea' after initiation of treatment (RR 0.36, 95% CI 0.13 to 0.98; 1 study, 56 participants; low-certainty evidence). Doxapram may result in little to no difference in failed extubation (RR 0.92, 95% CI 0.52 to 1.62; 1 study, 56 participants; low-certainty evidence). The evidence is very uncertain about the effect of doxapram on side effects causing cessation of therapy (RR 6.42, 95% CI 0.80 to 51.26; 2 studies, 85 participants; very low-certainty evidence). No studies reported need for positive pressure ventilation, chronic lung disease at 36 weeks' PMA, long-term neurodevelopmental outcomes in the three comparisons; failed extubation when compared to no treatment; and clinical apnea, death at any time during initial hospitalization, and side effects when compared to no treatment or alternative treatment. We identified two ongoing studies, one conducted in Germany and one in multiple centers in the Netherlands and Belgium. AUTHORS' CONCLUSIONS: In treating apnea of prematurity, doxapram may slightly reduce failure in apnea reduction when compared to no treatment and there may be little to no difference in side effects against both no treatment and alternative treatment. The evidence is very uncertain about the need for positive pressure ventilation when compared to no treatment or alternative treatment and about failed apnea reduction when used as alternative or adjunct therapy to methylxanthine. For use to prevent reintubation, doxapram may reduce apnea episodes when administered in adjunct to methylxanthine, but with little to no difference in failed extubation. The evidence is very uncertain about doxapram's effect on death when used as adjunct therapy to methylxanthine and about failed extubation when used as alternative or adjunct therapy to methylxanthine. There is a knowledge gap about the use of doxapram as a therapy to prevent apnea. More studies are needed to clarify the role of doxapram in the treatment of apnea of prematurity, addressing concerns about long-term outcomes. The ongoing studies may provide useful data.

Caffeine versus other methylxanthines for the prevention and treatment of apnea in preterm infants.

BACKGROUND: Methylxanthines, including caffeine, theophylline, and aminophylline, work as stimulants of the respiratory drive, and decrease apnea of prematurity, a developmental disorder common in preterm infants. In particular, caffeine has been reported to improve important clinical outcomes, including bronchopulmonary dysplasia (BPD) and neurodevelopmental disability. However, there is uncertainty regarding the efficacy of caffeine compared to other methylxanthines. OBJECTIVES: To assess the effects of caffeine compared to aminophylline or theophylline in preterm infants at risk of apnea, with apnea, or in the peri-extubation phase. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, Epistemonikos, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), and clinicaltrials.gov in February 2023. We also checked the reference lists of relevant articles to identify additional studies. SELECTION CRITERIA: Studies: randomized controlled trials (RCTs) and quasi-RCTs Participants: infants born before 34 weeks of gestation for prevention and extubation trials, and infants born before 37 weeks of gestation for treatment trials Intervention and comparison: caffeine versus theophylline or caffeine versus aminophylline. We included all doses and duration of treatment. 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), risk difference (RD), and 95% confidence intervals (CI) for categorical data, and mean, standard deviation, and mean difference for continuous data. We used the GRADE approach to evaluate the certainty of evidence. MAIN RESULTS: We included 22 trials enrolling 1776 preterm infants. The indication for treatment was prevention of apnea in three studies, treatment of apnea in 13 studies, and extubation management in three studies. In three studies, there were multiple indications for treatment, and in one study, the indication for treatment was unclear. In 19 included studies, the infants had a mean gestational age between 28 and 32 weeks and a mean birth weight between 1000 g and 1500 g. One study's participants had a mean gestational age of more than 32 weeks, and two studies had participants with a mean birth weight of 1500 g or more. Caffeine administrated for any indication may result in little to no difference in all-cause mortality prior to hospital discharge compared to other methylxanthines (RR 1.12, 95% CI 0.68 to 1.84; RD 0.02, 95% CI -0.05 to 0.08; 2 studies, 396 infants; low-certainty evidence). Only one study enrolling 79 infants reported components of the outcome moderate to severe neurodevelopmental disability at 18 to 26 months. The evidence is very uncertain about the effect of caffeine on cognitive developmental delay compared to other methylxanthines (RR 0.17, 95% CI 0.02 to 1.37; RD -0.12, 95% CI -0.24 to 0.01; 1 study, 79 infants; very low-certainty evidence). The evidence is very uncertain about the effect of caffeine on language developmental delay compared to other methylxanthines (RR 0.76, 95% CI 0.37 to 1.58; RD -0.07, 95% CI -0.27 to 0.12; 1 study, 79 infants; very low-certainty evidence). The evidence is very uncertain about the effect of caffeine on motor developmental delay compared to other methylxanthines (RR 0.50, 95% CI 0.13 to 1.96; RD -0.07, 95% CI -0.21 to 0.07; 1 study, 79 infants; very low-certainty evidence). The evidence is very uncertain about the effect of caffeine on visual and hearing impairment compared to other methylxanthines. At 24 months of age, visual impairment was seen in 8 out of 11 infants and 10 out of 11 infants in the caffeine and other methylxanthines groups, respectively. Hearing impairment was seen in 2 out of 5 infants and 1 out of 1 infant in the caffeine and other methylxanthines groups, respectively. No studies reported the outcomes cerebral palsy, gross motor disability, and mental development. Compared to other methylxanthines, caffeine may result in little to no difference in BPD/chronic lung disease, defined as 28 days of oxygen exposure at 36 weeks' postmenstrual age (RR 1.40, 95% CI 0.92 to 2.11; RD 0.04, 95% CI -0.01 to 0.09; 3 studies, 481 infants; low-certainty evidence). The evidence is very uncertain about the effect of caffeine on side effects (tachycardia, agitation, or feed intolerance) leading to a reduction in dose or withholding of methylxanthines compared to other methylxanthines (RR 0.17, 95% CI 0.02 to 1.32; RD -0.29, 95% CI -0.57 to -0.02; 1 study, 30 infants; very low-certainty evidence). Caffeine may result in little to no difference in duration of hospital stay compared to other methylxanthines (median (interquartile range): caffeine 43 days (27.5 to 61.5); other methylxanthines 39 days (28 to 55)). No studies reported the outcome seizures. AUTHORS' CONCLUSIONS: Although caffeine has been shown to improve important clinical outcomes, in the few studies that compared caffeine to other methylxanthines, there might be little to no difference in mortality, bronchopulmonary dysplasia, and duration of hospital stay. The evidence is very uncertain about the effect of caffeine compared to other methylxanthines on long-term development and side effects. Although caffeine or other methylxanthines are widely used in preterm infants, there is little direct evidence to support the choice of which methylxanthine to use. More research is needed, especially on extremely preterm infants born before 28 weeks of gestation. Data from four ongoing studies might provide more evidence on the effects of caffeine or other methylxanthines.

Effect of prophylactic caffeine in the treatment of apnea in very low birth weight infants: a meta-analysis.

OBJECTIVE: The purpose of this meta-analysis is to investigate the effect of prophylactic caffeine use in the treatment of apnea and other clinical outcomes in very low birth weight infants. METHODS: We searched PubMed, Embase, Web of Science, Scopus, EBSCO, CNKI, and Cochrane databases for all relevant studies up to May 20, 2022. The meta-analysis was carried out using Stata16.0 and RevMan5.4 software. RESULTS: Eleven randomized controlled trials were evaluated, including a total of 4375 very low birth weight infants. The results demonstrated that prophylactic caffeine use was linked with a significantly lower probability of AOP (OR 0.31, 95% CI: 0.19-0.49, p < .001), duration of mechanical ventilation and oxygen therapy when compared to the control group. It also reduced the incidence of BPD (OR 0.62, 95% CI: 0.54-0.71, p < .001), PDA (OR 0.49, 95% CI: 0.30-0.80, p = .005) and ROP (OR 0.76, 95% CI: 0.65-0.90, p = .001), without raising the risk of NEC, IVH and death before hospital discharge (p > .05). CONCLUSION: This meta-analysis confirmed the beneficial effects of prophylactic caffeine in preventing apnea of prematurity and improving clinical outcomes.

Alteration of monoaminergic systems in the caudal medulla and its possible link to diurnal increase of apnea in a mouse model of Rett syndrome.

PURPOSE: Methyl-CpG binding protein 2 (MeCP2)-deficient (Mecp2-/y) mice exhibit apneas that resemble respiratory abnormalities observed in Rett syndrome (RTT) patients. The present study aimed to clarify whether Mecp2-/y mice show diurnal variations in apnea as seen in RTT and how the MeCP2 deficiency affects monoaminergic systems that control breathing. METHODS: In 7-week-old Mecp2-/y mice, 24 h variation of apnea and effects of milnacipran, a serotonin/noradrenaline reuptake inhibitor, on the apnea were evaluated. The number of vesicular monoamine transporter 2 (VMAT2)-immunoreactive puncta in the caudal medulla was counted. Further, the effects of valproate (VPA) on the expression of tyrosine hydroxylase (TH) mRNA in the ventrolateral medulla of mice were assessed by RT-qPCR. RESULTS: Apnea occurred more frequently during the light phase under a 12:12 h light/dark environment in Mecp2-/y mice and milnacipran reduced apnea during the light phase but not during the dark phase. The number of VMAT2-immunoreactive puncta was reduced in Mecp2-/y mice. VPA treatment significantly increased TH mRNA expression in Mecp2-/y mice. CONCLUSION: Alteration of monoaminergic systems in the caudal medulla of Mecp2-/y mice is potentially relevant to the light-sensitive diurnal increase of apnea, and an improvement in monoaminergic neurotransmission can ameliorate the diurnal increase of apnea in Mecp2-/y mice.

Effect of Prophylactic Caffeine on Noninvasive Respiratory Support in Preterm Neonates Weighing 1250-2000 g: A Randomized Controlled Trial.

BACKGROUND: Caffeine is commonly used to prevent or treat apnea in preterm neonates. The present trial was designed to determine the effect of caffeine on reducing the time required for nasal continuous positive airway pressure (NCPAP) in neonates with respiratory distress syndrome (RDS). METHODS: In a randomized controlled trial, a total of 90 neonates (birth weight between 1250 and 2000 g) who were clinically diagnosed with RDS were subjected to random assignment to one of the two groups of caffeine (n=45) or control (n=45). Infants in the caffeine group received 20 mg/kg caffeine as the initial dose, and then 10 mg/kg daily as the maintenance dose. Infants in the control group did not receive any placebo or similar drugs. The primary outcome was the duration time of respiratory support with NCPAP. RESULTS: The mean (SD) duration of NCPAP differed significantly and was shorter among the infants in the caffeine group than those assigned to the control group (41.53 (43.25) versus 78.48 (114.25) hours, respectively; mean difference: -36.95; 95%CI: -73.14, -0.76; P = 0.04). Apnea of prematurity (AOP) occurred in 2 (4.4%) newborns in the caffeine group and in 9 (20%) of the infants in the control condition [proportion difference: -15.6% (-29.8,-1.8); (P = 0.02)]. The incidence of intraventricular hemorrhage (IVH) was higher in the control group than in the caffeine group after one week (P = 0.03). The incidence of chronic lung disease (CLD), infection, necrotizing enterocolitis (NEC), seizure, vomiting and pneumothorax was similar in the two groups. CONCLUSION: The results suggest that preventative caffeine can reduce the duration of NCPAP support in neonates with RDS.

Prophylactic versus therapeutic caffeine for apnea of prematurity: a randomized controlled trial.

BACKGROUND: Therapeutic initiation of methyxanthines for treatment of apnea in preterm infants was the standard policy. Caffeine therapy is beneficial for various outcomes of preterm infants. AIM: To evaluate the efficacy of early prophylactic compared to routine therapeutic caffeine therapy on duration of oxygen support and other outcomes of preterm infants. METHODS: In a randomized controlled trial including preterm infants < 32 weeks' gestation, prophylactic (in the first 72 h of life) versus therapeutic (only if apnea exists or infant requires mechanical ventilation) decision of caffeine was compared. The primary outcome was the duration of oxygen therapy. Secondary outcomes included duration of respiratory support modalities; bronchoplumonary dysplasia (BPD); necrotizing enterocolitis; intra-ventricular hemorrhage; retinopathy of prematurity; length of hospital stay (LOS); neonatal mortality; and caffeine side effects. RESULTS: We enrolled 90 infants in the prophylactic and 91 infants in therapeutic groups respectively. Prophylactic caffeine decreased the duration of oxygen therapy [median and IQR of 28 (18-36) days versus 34 (23-51) days, p = .005 respectively]. Prophylactic caffeine significantly decreased the durations of respiratory support modalities, LOS, and incidences of mild to moderate BPD without reported effects on the incidence of severe BPD or other clinical outcomes compared to therapeutic caffeine. A significantly higher proportion of infants in the prophylactic caffeine group did not require mechanical ventilation during their NICU admission and a significant lower proportion required late mechanical ventilation compared to the prophylactic caffeine group. CONCLUSION: Prophylactic caffeine decreased the duration of oxygen therapy, invasive and noninvasive ventilation, incidences of mild to moderate BPD, and LOS in preterm infants.

A Randomized Controlled Trial Comparing Two Doses of Caffeine for Apnoea in Prematurity.

Caffeine is the most commonly used methyl xanthine for the prevention of apnoea in prematurity, but the ideal dose was uncertain, until now. This study compared two doses of caffeine for the prevention of apnoea in prematurity. A clinical trial was conducted on 78 preterm infants ≤32 weeks in Neonatal Intensive Care Unit. They were randomly allocated to receive the intervention (loading 40 mg/kg/day and maintenance of 20 mg/kg/day) or the control (loading 20 mg/kg/day and maintenance of 10 mg/kg/day) dose of caffeine. The primary outcome of the study was the frequency and total days of apnoea per duration of treatment for both groups. The frequency of apnoea ranged from zero to fourteen in the intervention group and zero to twelve in the control group. There was no statistically significant difference between the groups, with a p-value of 0.839. The number of days of apnoea was also similar between both groups, with a p-value of 0.928. There was also no significant difference in adverse events between both regimens. This study did not support the use of higher doses of caffeine as a prevention for apnoea in prematurity.

Restoration of breathing after opioid overdose and spinal cord injury using temporal interference stimulation.

Respiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.

When to start and stop caffeine and why respiratory status matters.

Caffeine as tested in the CAP trial is safe and effective for preterm infants with birthweights less than 1250 g. Evidence for its use beyond the indications and timing used in this trial is of low quality and conflicting. Some studies suggest that earlier use of caffeine increases the risk of mortality while others suggest it has important benefits. It appears that infants with apnea of prematurity and those receiving assisted ventilation are the most likely to benefit from caffeine. Based on currently available evidence, routine early prescription of caffeine does not appear to be indicated. Infants continue to have potentially damaging episodes of hypoxia secondary to apnea beyond 34 weeks' postmenstrual age. It is unclear whether prolonged use of caffeine improves outcomes in these infants. Randomized trials to resolve these uncertainties are required. They need to be large, at least the size of the CAP trial, and include neurodevelopmental outcomes.

Early application of caffeine improves white matter development in very preterm infants.

The aim of this study was to evaluate the effect of early prophylactic caffeine treatment on white matter development in very preterm infants using cerebral magnetic resonance imaging. A total of 194 preterm infants (≤32 weeks gestational age) were randomly assigned to the caffeine (n = 96) or placebo (n = 93) treatment group and administered with either caffeine or placebo within 72 h after birth. Cerebral magnetic resonance imaging, including diffuse tensor imaging examination, was performed at 34-36 weeks of corrected gestational age, and the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured. In total, 160 infants were included in the final analysis, including 80 cases in the placebo group and 80 cases in the caffeine group. There were fewer instances of apnea of prematurity and shorter assisted ventilation times for infants in the caffeine group compared to the placebo group (p < 0.05). Infants in the caffeine group had significantly higher FA values in white matter, including the posterior limb of the internal capsule, the corpus callosum, the frontal, occipital, and parietal white matter, the cerebellum, and the cerebral peduncle, compared to infants in the placebo group. ADC values in the above white matter areas were significantly reduced in the caffeine group. However, there were no significant differences regarding the FA and ADC in the gray matter between the two groups. These results demonstrate that early administration of caffeine improves white matter micro-structural development in preterm infants, but with no significant effect on short-term complications related to prematurity.

Caffeine citrate maintenance doses effect on extubation and apnea postventilation in preterm infants.

BACKGROUND: Caffeine citrate is used to prevent apnea in premature infants and help in extubation of invasive ventilation, but the optimal dose remains undetermined. METHODS: Neonates born at less than 30 weeks gestation who had received invasive ventilation for at least 48 hours and a loading dose of 20 mg/kg caffeine citrate were randomly assigned into high (10 mg/kg daily) or low (5 mg/kg daily) maintenance dose groups. The drug was discontinued if no apnea occurred for 7 consecutive days. RESULTS: A total of 111 infants were assigned into the high (54) or low (57) dose groups. Extubation failure (16.7% vs 36.8%), age of extubation (8.2 ± 2.1 vs 10.7 ± 2.3 day), duration of invasive ventilation (7.2 ± 2.1 vs 8.5 ± 2.4 day), duration of ventilation before extubation (8.0 ± 1.8 vs 10.1 ± 1.9 day), and number of days of apnea (1.8 ± 1.3 vs 3.2 ± 1.1 day) were significantly lower in the high dose group than the low dose group. Difference in time until failure (6.7 ± 1.7d vs 7.0 ± 1.9d) and duration of nasal continuous positive airway pressure(7.8 ± 1.8 vs 8.0 ± 2.2 day) were not significant. Furthermore, no significant differences in the incidence of tachycardia (9.3% vs 12.3%), abdominal distension (16.7% vs 12.3%), feeding intolerance (3.7% vs 5.3%), or irritability (7.4% vs 5.3%) were observed between groups. CONCLUSIONS: A higher maintenance dose of caffeine citrate reduced the incidence of extubation failure and apnea of prematurity without increasing the occurrence of adverse reactions.

P2X3 receptor antagonism reduces the occurrence of apnoeas in newborn rats.

Hyperreflexia of the peripheral chemoreceptors is a potential contributor of apnoeas of prematurity (AoP). Recently, it was shown that elevated P2X3 receptor expression was associated with elevated carotid body afferent sensitivity. Therefore, we tested whether P2X3 receptor antagonism would reduce AoP known to occur in newborn rats. Unrestrained whole-body plethysmography was used to record breathing and from this the frequency of apnoeas at baseline and following administration of either a P2X3 receptor antagonist - AF-454 (5 mg/kg or 10 mg/kg s.c.) or vehicle was derived. In a separate group, we tested the effects of AF-454 (10 mg/kg) on the hypoxic ventilatory response (10 % FiO2). Ten but not 5 mg/kg AF-454 reduced the frequency of AoP and improved breathing regularity significantly compared to vehicle. Neither AF-454 (both 5 and 10 mg/kg) nor vehicle affected baseline respiration. However, P2X3 receptor antagonism (10 mg/kg) powerfully blunted hypoxic ventilatory response to 10 % FiO2. These data suggest that P2X3 receptors contribute to AoP and the hypoxic ventilatory response in newborn rats but play no role in the drive to breathe at rest.

Carfentanil toxicity in the African green monkey: Therapeutic efficacy of naloxone.

Carfentanil is an ultra-potent opioid with an analgesic potency 10,000 times that of morphine but has received little scientific investigation. Three experiments were conducted to evaluate the toxicity of carfentanil and the efficacy of naloxone in adult male African green monkeys. The first experiment determined the ED50 (found to be 0.71 µg/kg) of subcutaneous carfentanil for inducing bradypnea and/or loss of posture. Experiment 2 attempted to establish the ED50 of naloxone for rapidly reversing the bradypnea/loss of posture induced by carfentanil (1.15 µg/kg). Experiment 3 evaluated the effects of carfentanil (0.575 µg/kg) alone, the safety of naloxone (71-2841 µg/kg), and the efficacy of naloxone (71-710 µg/kg) administration at two time points following carfentanil (1.15 µg/kg) on operant choice reaction time. Collectively, these experiments characterized the temporal progression of carfentanil-induced toxic signs, determined the range of naloxone doses that restored respiratory and gross behavioral function, and determined the time course and range of naloxone doses that partially or completely reversed the effects of carfentanil on operant choice reaction time performance in African green monkeys. These results have practical relevance for the selection of opioid antagonists, initial doses, and expected functional outcomes following treatment of synthetic opioid overdose in a variety of operational/emergency response contexts.

Kölliker-Fuse/Parabrachial complex mu opioid receptors contribute to fentanyl-induced apnea and respiratory rate depression.

Overdoses caused by the opioid agonist fentanyl have increased exponentially in recent years. Identifying mechanisms to counter progression to fatal respiratory apnea during opioid overdose is desirable, but difficult to study in vivo. The pontine Kölliker-Fuse/Parabrachial complex (KF/PB) provides respiratory drive and contains opioid-sensitive neurons. The contribution of the KF/PB complex to fentanyl-induced apnea was investigated using the in situ arterially perfused preparation of rat. Systemic application of fentanyl resulted in concentration-dependent respiratory disturbances. At low concentrations, respiratory rate slowed and subsequently transitioned to an apneustic-like, 2-phase pattern. Higher concentrations caused prolonged apnea, interrupted by occasional apneustic-like bursts. Application of CTAP, a selective mu opioid receptor antagonist, directly into the KF/PB complex reversed and prevented fentanyl-induced apnea by increasing the frequency of apneustic-like bursting. These results demonstrate that countering opioid effects in the KF/PB complex is sufficient to restore phasic respiratory output at a rate similar to pre-fentanyl conditions, which could be beneficial in opioid overdose.

Effect of Virgin Coconut Oil Application on the Skin of Preterm Newborns: A Randomized Controlled Trial.

BACKGROUND: Preterm constitutes a major part of neonatal mortality, particularly in India. Due to dermal immaturity, preterm neonates are susceptible to various complications like infection, hypothermia, etc. Emollient application is a traditional practice in our subcontinent. AIMS: To find out the efficacy of coconut oil application for skin maturity, prevention of sepsis, hypothermia and apnea, its effect on long-term neurodevelopment and adverse effect of it, if any. MATERIAL AND METHODS: A randomized controlled trial was conducted in the rural field practice area of Department of Community Medicine, Burdwan Medical College from March 2014 to August 2018. Preterm born in the study period was divided into Group A (received virgin coconut oil application) and Group B (received body massage without any application). Neonatal skin condition was assessed on 7th, 14th, 21st and 28th day of life. Neurodevelopmental status was assessed on 3rd, 6th and 12th months. RESULTS: A total of 2294 preterm were included in the study. Groups A and B consisted of 1146 and 1148 preterm infants, consecutively. Mean gestational age of the study population was 31.9 ± 3.4 weeks and 50.4% were male. Mean weight loss in first few days was less in group A but mean weight gain per day was higher in group B. Lesser incidences of hypothermia and apnea, and better skin maturity and neurodevelopmental outcome were noted in group A. No significant adverse effect was noted with coconut oil application. CONCLUSION: Use of coconut oil helps in dermal maturity and better neurodevelopmental outcome. Further studies are warranted for universal recommendation.

Influence of prevention of caffeine citrate on cytokine profile and bronchopulmonary dysplasia in preterm infants with apnea.

BACKGROUND: This study aims to investigate the preventive effects of caffeine citrate on cytokine profile and bronchopulmonary dysplasia (BPD) in preterm infants with apnea. METHODS: Preterm infants with apnea who were born at less than 32 weeks of gestational age and birth weight ≤1500 g were randomly divided into caffeine citrate prevention group and caffeine citrate treatment group. Preterm infants in caffeine citrate prevention group who were at risk of developing recurrent apnea were given to caffeine citrate within 8 h after birth. Those in caffeine citrate treatment group experienced apnea after birth were given to caffeine citrate for treatment. Preterm infants in both groups were treated with the same respiratory management and other conventional therapy. After drug discontinuation, levels of cytokine profile, and incidence of BPD were compared between two groups. RESULTS: A total of 56 preterm infants were enrolled. Differences in gestational age (P=0.11) and birth weight (P=0.251) were not statistically significant. Differences in application time of caffeine citrate (P=0.356), hour of ventilator use (P=0.152), length of stay (P=0.416) and BPD morbidity (P=1.00) between two groups were not statistically significant. At birth, there were no statistically significant in levels of IL-6 (P=0.063) and IL-8 (P=0.125) between two groups. After conventional therapy, levels of IL-6 (P=0.001) and IL-8 (P=0.001) significantly decreased in caffeine citrate prevention group compared with those in caffeine citrate treatment group. CONCLUSIONS: Prevention usage of caffeine citrate in preterm infants with apnea could reduce the level of cytokine profile and the incidence of BPD.

High-Flow Nasal Cannula and Mandibular Advancement Bite Block Decrease Hypoxic Events during Sedative Esophagogastroduodenoscopy: A Randomized Clinical Trial.

During sedated endoscopic examinations, upper airway obstruction occurs. Nasal breathing often shifts to oral breathing during open mouth esophagogastroduodenoscopy (EGD). High-flow nasal cannula (HFNC) which delivers humidified 100% oxygen at 30 L min-1 may prevent hypoxemia. A mandibular advancement (MA) bite block with oxygen inlet directed to both mouth and nose may prevent airway obstruction during sedated EGD. The purpose of this study was to evaluate the efficacy of these airway devices versus standard management. One hundred and eighty-nine patients were assessed for eligibility. One hundred and fifty-three were enrolled. This study randomly assigned eligible patients to three arms: the standard bite block and standard nasal cannula, HFNC, and MA bite block groups. EGD was performed after anaesthetic induction. The primary endpoint was the oxygen desaturation area under curve at 90% (AUCDesat). The secondary endpoints were percentage of patients with hypoxic, upper airway obstruction, and apnoeic and rescue events. One hundred and fifty-three patients were enrolled. AUCdesat was significantly lower for HFNC and MA bite blocks versus the standard management (p= 0.019). The HFNC reduced hypoxic events by 18% despite similar airway obstruction and apnoeic events as standard group. The MA bite block reduced hypoxic events by 12% and airway obstructions by 32%. The HFNC and MA groups both showed a 16% and 14% reduction in the number of patients who received rescue intervention, respectively, compared to the standard group. The HFNC and MA bite block may both reduce degree and duration of hypoxemia. HFNC may decrease hypoxemic events while maintaining nasal patency is crucial during sedative EGD. The MA bite block may prevent airway obstruction and decrease the need for rescue intervention.

What Is New about Transfusions for Preterm Infants? An Update.

Currently the question of whether to maintain a higher hemoglobin level by transfusing more liberally, as opposed to a more restrictive strategy with lower hemoglobin maintenance levels, has not been answered. We review summarized conclusions of a Cochrane systematic review and meta-analysis of 614 infants in 4 randomized controlled trials (RCT) pooling data. This suggests potential benefits of higher hemoglobin levels, i.e., a possible improved cognition of infants at 18-21 months' corrected age and a reduction of apnea. However, the data on cognition is hypothesis generating as it derives from a post hoc analysis from a single trial in 451 infants. Moreover, the data on apnea need confirmation in larger trials. The effect of adding data of cognitive 2-year outcomes of 1,744 infants from 2 RCT, which will be reported soon, should expand our understanding. This new data will need to be integrated with the older generation of RCTs but also with emerging suggestions from observational data on potential risks of blood transfusions. We discuss some of these warnings from observational studies. Finally, we ask whether we are ready to individualize blood transfusion to physiological measures made in individual infants, and we point to some current difficulties hindering this step.