Statistics from Altmetric.com
You are an intensive care registrar who has taken over the care of a 3 week old baby boy diagnosed as having clinical bronchiolitis (now found to be RSV+). He was initially admitted and ventilated because of increasing respiratory distress and apnoeas. His ventilatory requirements are increasing and gas exchange is getting worse. You have just finished your stint on neonates and recall hearing that surfactant has been used on infants with bronchiolitis in trials. You wonder if it may help this child.
Structured clinical question
In an infant with severe RSV+ bronchiolitis requiring ventilation [patient], does endotracheal surfactant [intervention]; (a) improve ventilation/gas exchange parameters; and (b) shorten the duration of ventilation or intensive care stay [outcome]?
Search strategy and outcome
A search string of (a) [bronchiolitis] and [surfactant] and (b) [respiratory syncytial virus] and [bronchiolitis] was used.
Cochrane database—topic registered only.
PubMed—three relevant papers; 85 hits.
SUMSearch—nothing other than the above.
See table 3.
To date no systematic review has been performed on this topic, but the number of trials published to date is very small. Thus there is limited evidence available on the therapeutic merit of surfactant in bronchiolitis.
Both trials summarised above show an improvement in ventilation and gas exchange parameters with surfactant. However other than these (surrogate) end points there is a lack of evidence to show that an infant with severe bronchiolitis will either require a shorter period of ventilation, or a reduced time in an intensive care setting.
The earlier trial (Vos et al), while showing statistically significant reductions in ventilation time and intensive care stay, had some limiting factors. Blinding was not carried out and only four cases were shown to be RSV+. Given that bronchiolitis can be due to different viruses and these all could affect children with varying severities, this is an important point to bear in mind when considering RSV+ bronchiolitis. Interestingly the average age of the cases in Vos et al’s trial was 10.4 months; this may not reflect the typical PICU bronchiolitic “intake” in many other units, bronchiolitis usually being more severe in younger babies. It is worth asking therefore how generalisable this paper’s findings are, given that they relate to infants who are not all RSV+ and who are older than those usually seen in a PICU.
CLINICAL BOTTOM LINE
The use of surfactant in ventilated infants with severe bronchiolitis has been associated with improved oxygenation and ventilatory parameters in the short term.
Surfactant has not been shown to decrease the duration of ventilation, or the length of admission to a paediatric intensive care unit.
Surfactant treatment for bronchiolitis remains an experimental intervention to be used as part of a clinical trial.
The more recent trial by Tibby et al was a blinded trial, but was of insufficient power to show statistically significant changes in ventilation and PICU stay. There were several differences between this trial (Tibby et al) and the previous one which warrant consideration. This trial comprised younger patients (mean age <10 weeks), all of whom were RSV+ and were treated with larger doses of surfactant (100 mg/kg v 50 mg/kg). Thus as well as knowing their RSV status, we know they were more representative of a PICU population of bronchiolitics. However, with two trials both using different doses, we can ask which dose has the optimal efficacy.
No complications were reported in these studies, but it is worth reflecting on the fact that surfactant treatment does not go without its own hazards such as a small increase in the rate of pulmonary haemorrhage. Furthermore, surfactant is not cheap and there needs to be evidence showing real clinical improvements rather than improved short term physiological parameters to recommend its use. More or larger trials (including phase 2 trials or trials with multiple arms to look at surfactant doses) are needed to look at the role of surfactant in improving time based outcomes, such as ventilation duration and length of hospital/PICU stay and survival.