Randomized, controlled, blinded trial of doxapram for extubation of the very low birthweight infant

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.

Doxapram Treatment for Apnea of Prematurity: A Systematic Review

BACKGROUND

Apnea of prematurity (AOP) is a common complication of preterm birth, for which caffeine is the first treatment of choice. In case of persistent AOP, doxapram has been advocated as an additional therapy.

OBJECTIVE

To identify and appraise all existing evidence regarding efficacy and safety of doxapram use for AOP in infants born before 34 weeks of gestational age.

METHODS

All studies reporting on doxapram use for AOP were identified by searching electronic databases, references from relevant studies, and abstracts from the Societies for Pediatric Research. Two reviewers independently assessed study eligibility and quality, and extracted data on study design, patient characteristics, efficacy and safety outcomes.

RESULTS

The randomized controlled trials showed less apnea during doxapram treatment when compared to placebo, but no difference in treatment effect when compared to theophylline. No serious adverse effects were reported. We identified 28 observational studies consisting mainly of cohort studies and case series (n = 1,994). There was considerable heterogeneity in study design and quality. Most studies reported a positive effect of doxapram on apnea rate. A few studies reported on long-term outcomes with conflicting results. A range of possible doxapram-related short-term adverse effects were reported, sometimes associated with the use of higher doses.

CONCLUSION

Based on the limited number of studies and level of evidence, no firm conclusions on the efficacy and safety of doxapram in preterm infants can be drawn. For this reason, routine use cannot be recommended. A large multicenter randomized controlled trial is urgently needed to provide more conclusive evidence.

Risks and benefits of therapies for apnoea in premature infants

Apnoea in infants can result from a wide range of causes, and requires thorough evaluation before deciding on appropriate treatment. Continuous monitoring of premature infants with apnoea is mandatory in order to define the pathophysiology and type of apnoea; selection of treatment involves careful assessment of aetiology, as well as efficacy and tolerability in each individual case. The objective of treatment is to prevent the deleterious consequences of apnoeas that last >20 seconds and/or are associated with bradycardia, cyanosis or pallor, and occur more often than once an hour over a 12-hour period. Apnoea management involves both pharmacological and nonpharmacological treatment. We suggest methylxanthines as first-line therapy for idiopathic apnoeas; evidence suggests that caffeine is better tolerated and as efficacious as theophylline (since it is particularly efficacious against the 'central' component of idiopathic apnoea of prematurity). If treatment fails, additional measures such as doxapram may be appropriate when hypoventilation is present, or nasal continuous positive airway pressure when upper airway instability or obstructive apnoeas are predominant. Apnoea prophylaxis is an additional reason to advocate prenatal maturation with betamethasone. Weaning from treatment is attempted 4 to 5 days after complete resolution of apnoea, beginning with the last treatment introduced. Monitoring should be maintained for 4 to 5 days to detect any relapse of recurrent and severe apnoeas, which would lead to the resumption of the most recently withdrawn treatment.

Prophylactic doxapram for the prevention of morbidity and mortality in preterm infants undergoing endotracheal extubation

BACKGROUND

When preterm infants have been given intermittent positive pressure ventilation (IPPV) for respiratory failure, weaning from support and tracheal extubation may be difficult. A significant contributing factor is thought to be the relatively poor respiratory effort and tendency to develop hypoventilation and apnea, particularly in very preterm infants. Doxapram stimulates breathing and appears to act via stimulation of both the peripheral chemoreceptors and the central nervous system. This effect might increase the chance of successful tracheal extubation.

OBJECTIVES

In preterm infants being weaned from IPPV and in whom endotracheal extubation is planned, does treatment with doxapram reduce the use of intubation and IPPV, or reduce other morbidity, without clinically important side effects? In this regard, how does doxapram compare with standard treatment or with an alternative treatment such as methylxanthine or CPAP? Subgroup analyses were prespecified according to birth weight and/or gestational age, use of co-interventions (methylxanthines or nasal CPAP), and route of administration (intravenous or oral).

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group as outlined in the Cochrane Library was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE and EMBASE.

SELECTION CRITERIA

Eligible studies included published trials utilising random or quasi-random patient allocation in which preterm or low birth weight infants being weaned from IPPV were given doxapram compared with standard care or other treatments, to facilitate weaning from IPPV and endotracheal extubation. Trials were independently assessed by the authors before inclusion.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Collaboration and its Neonatal Review Group were used. Each author extracted data separately; the results were compared and any differences resolved. The data were synthesized using the standard method of Neonatal Review Group with use of relative risk and risk difference.

MAIN RESULTS

Two trials involving a total of 85 infants compared doxapram and placebo. In both the individual trials and the meta-analyses there were no significant differences between the doxapram and placebo groups in any of the outcomes (failed extubation, death before discharge, respiratory failure, duration of IPPV, side effects, oxygen at 28 days or oxygen at discharge). There was a trend towards an increase in side effects (hypertension or irritability leading to cessation of treatment) in the doxapram group [summary RR 3.21 (0.53, 19.43). In one of these two trials (Huon 1998) an 'alarming rise in blood pressure' occurred in five infants in the doxapram group and none of the controls, although in only one was treatment withdrawn. One additional trial involving only eight infants compared doxapram with aminophylline, but there were insufficient data for meaningful analysis.

REVIEWER'S CONCLUSIONS

The evidence does not support the routine use of doxapram to assist endotracheal extubation in preterm infants who are eligible for methylxanthine and/or CPAP. The results should be interpreted with caution because the small number of infants studied does not allow reliable assessment of the benefits and harms of doxapram. Further trials are required to evaluate the benefits and harms of doxapram compared with no treatment or with other treatments, such as methylxanthines or CPAP, to evaluate whether it is more effective in infants not responding to these other treatments, and to assess whether the drug is effective when given orally.