Continuous negative extrathoracic pressure or continuous positive airway pressure for acute hypoxemic respiratory failure in children

Abstract

Background: Acute hypoxemic respiratory failure (AHRF) is an important cause of mortality and morbidity in the pediatric age group. Despite varied etiologies and different population characteristics the aims of therapy are to achieve adequate oxygenation and ventilation. Positive pressure ventilation is currently the standard of care. It is ordinarily provided by intubation and mechanical ventilation, which is associated with a number of well recognized complications. Continuous negative extrathoracic pressure ventilation (CNEP) or continuous positive airway pressure ventilation delivered via non-invasive approaches (Ni-CPAP) have shown certain beneficial effects in animal and uncontrolled human studies. In a systematic review of studies involving neonates, continuous distending pressure using either CNEP or CPAP (applied via face mask) was associated with reduction in mortality but with an increased incidence of pneumothoraces, in neonates.

Objectives: The primary objective of this review was to assess the effectiveness of CNEP and Ni-CPAP in pediatric patients with AHRF due to non-cardiogenic causes.

Search strategy: A literature search was performed using following databases: Cochrane Central Register of Controlled Trials (December 2002); MEDLINE (January 1966 to December 2002); EMBASE (1980 to December 2002); CINAHL (1982 to December 2002); published abstracts from the meetings of the American Thoracic Society and Pediatric Critical Care Meetings (1992 to 2001); and bibliographies of identified articles and asking the experts in the field.

Selection criteria: Selection criteria applied to the clinical trials were: the population were children (at least 1 month old and less than 18 years of age at the time of randomization); patients met the criteria for diagnosis of AHRF; intervention was either CNEP or Ni-CPAP versus standard therapy (positive pressure ventilation); the trial was randomized or quasi-randomized; and at least one of the primary or secondary outcomes were reported.

Data collection and analysis: The methodological quality of included study was assessed using the following criteria: concealment of randomization, blinding of intervention, completeness of follow up and blinding of outcome measurements. Data on relevant outcomes were abstracted and the effect size was estimated by calculating relative risk (RR) with 95% confidence intervals (CI) and risk difference (95% CI).

Main results: One eligible study was identified which was published in abstract format. Thirty three infants (18 in the control group and 15 in the CNEP group) with a clinical diagnosis of bronchiolitis and oxygen requirement of greater than 40% were studied. There was reduction in the oxygen requirement (less than 30% within one hour of initiation of therapy) in four patients in the CNEP group compared to none in the control group (typical RR 10.7, 95% CI 0.6, 183.9). One infant required positive pressure ventilation and one infant required nasal CPAP in the control group while all infants in the CNEP group were managed without intubation (typical RR for both outcomes 0.40, 95% CI 0.02, 9.06).

Implication for practice: There is a lack of well designed, large controlled experiments comparing use of noninvasive modes of respiratory support in children with AHRF. Uncontrolled evidence of reduction in the intubation and hospital stay needs confirmation in proper studies evaluating risks involved with these practices. Implication for research: It is unlikely that CNEP or Ni-CPAP will have significant impact on mortality in AHRF, however, even a small reduction may be very important. Studies assessing other outcomes such as avoidance of intubation and its associated complications, reduction in hospital stay and improvement in patient comfort are also valuable in assessing the overall impact of these strategies.