The contribution of induced sputum sampling to surveillance of lower respiratory tract microbiology in children with Cystic Fibrosis

 Cystic Fibrosis / Posted 2 years ago

Cystic fibrosis (CF) is an inherited condition where the lungs and digestive system become clogged with mucus. Lung infection is common and needs to be treated aggressively with antibiotics even if it isn’t causing many symptoms. Doctors need to use different antibiotics for different types of infection. In order to identify which bacteria is causing the infection, the child is often asked to give a cough swab, so that a sample of their airway liquids can be sent to the lab to see if anything grows. Cough swabs are relatively easy to obtain but are not as good a test as bronchoscopy, where a fibre-optic camera is put down into the large airway of the lungs so that mucus samples can be taken directly from the lower airway. Obviously having a bronchoscopy is a much larger procedure than having a cough swab, but sometimes it is necessary. Some CF centres feel everyone with CF should have a bronchoscopy every year. This study tests a third way of getting samples from the airway called induced sputum. This is a little bit more complicated than a cough swab but much less complicated than having a bronchoscopy. It involves the child inhaling a fine mist of salt water and getting some physiotherapy. The salt water inhalation causes the phlegm (or sputum) to loosen up so that it can be more easily coughed up from the lower airway. The aim of this study is to compare the induced sputum test to a cough swab, a throat swab and a nasal swab. If the child is going to have a bronchoscopy because their doctor feels he/she needs one, then the results will be compared to the results of the bronchoscopy as well. The aim is to find out just how beneficial induced sputum really is, if it is done just once in the year, as part of the annual review, over and above the many cough swabs that are taken over the year. Induced sputum can be done in the outpatient clinic or in the hospital ward and takes about 30 minutes. The technique is safe and used routinely in children with other respiratory illnesses. However, this kind of study needs to be done before using the induced sputum technique routinely in patients with CF, to make sure that the procedure is well tolerated and also that it makes a worthwhile contribution to improving healthcare.

Who can participate?
Patients aged 6 months to 18 years with cystic fibrosis undergoing bronchoscopy under the care of South, West and Mid Wales Paediatric CF centre

What does the study involve?
One of the CF physiotherapists takes a cough swab, a throat swab and a nasal swab and then starts the procedure for induced sputum. Oxygen levels and heart rate are monitored during the procedure. If the child is over 7 years of age then he/she is asked to do a lung function test before the procedure starts. The procedure involves a salty nebuliser (hypertonic saline) which lasts about 15 minutes. After each 5 minute period, the physiotherapist makes an assessment of the chest and gives appropriate physiotherapy or guides the child through breathing exercises to try and mobilise secretions. Any secretions are collected either into a pot, or by suction from the back of the throat. Lung function is tested again at the end of the procedure if appropriate. The final step is to take another cough swab.

What are the possible benefits and risks of participating?
The main benefit of this study is for the CF community as a whole, to find out whether induced sputum should become part of routine care. There are no immediate benefits to the patient from taking part in this study, but should any organisms be identified from the samples taken, then appropriate treatment is prescribed. All of the procedures used in this study are already used by doctors in the treatment of children. Sometimes the salty nebuliser can make the child cough and some children can wheeze. Generally it is well tolerated in all age groups.

  • Inclusion Criteria : Cystic fibrosis patients aged 6 moths to 18 years under the care of the Childrens’ CF unit, Cardiff 1. Those attending for clinically indicated bronchoscopy 2. Those attending for routine surgery under GA, when surveillance bronchoscopy is standard of care at UHW 3. Those admitted for treatment of a chest exacerbation 4. Those attending for annual review in outpatient clinic
  • Exclusion Criteria : Clinical grounds as defined by attending consultant. Previous serious reaction to hyper-tonic saline nebulisation
  • Study start date : 23/01/2012
  • Study end date : 31/12/2021
  • Wales-Based Study Contact : Dr Julian Forton
  • Principal Investigator : Dr Julian Forton

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