Abstract: We included 12 RCTs (1249 participants), three more than the previous Cochrane review, comparing physiotherapy with no intervention. Five trials (246 participants) evaluated conventional techniques (vibration and percussion plus postural drainage), and seven trials (1003 participants) evaluated passive flow-oriented expiratory techniques: slow passive expiratory techniques in four trials, and forced passive expiratory techniques in three trials. Conventional techniques failed to show a benefit in the primary outcome of change in severity status of bronchiolitis measured by means of clinical scores (five trials, 241 participants analysed). Safety of conventional techniques has been studied only anecdotally, with one case of atelectasis, the collapse or closure of the lung resulting in reduced or absent gas exchange, reported in the control arm of one trial. Slow passive expiratory techniques failed to show a benefit in the primary outcomes of severity status of bronchiolitis and in time to recovery (low quality of evidence). Three trials analysing 286 participants measured severity of bronchiolitis through clinical scores, with no significant differences between groups in any of these trials, conducted in patients with moderate and severe disease. Only one trial observed a transient significant small improvement in the Wang clinical score immediately after the intervention in patients with moderate severity of disease. There is very low quality evidence that slow passive expiratory techniques seem to be safe, as two studies (256 participants) reported that no adverse effects were observed. Forced passive expiratory techniques failed to show an effect on severity of bronchiolitis in terms of time to recovery (two trials, 509 participants) and time to clinical stability (one trial, 99 participants analysed). This evidence is of high quality and corresponds to patients with severe bronchiolitis. Furthermore, there is also high quality evidence that these techniques are related to an increased risk of transient respiratory destabilisation (risk ratio (RR) 5.4, 95% confidence interval (CI) 1.6 to 18.4, one trial) and vomiting during the procedure (RR 10.2, 95% CI 1.3 to 78.8, one trial). Results are inconclusive for bradycardia with desaturation (RR 1.0, 95% CI 0.2 to 5.0, one trial) and bradycardia without desaturation (RR 3.6, 95% CI 0.7 to 16.9, one trial), due to the limited precision of estimators. However, in mild to moderate bronchiolitis patients, forced expiration combined with conventional techniques produced an immediate relief of disease severity (one trial, 13 participants). None of the chest physiotherapy techniques analysed in this review (conventional, slow passive expiratory techniques or forced expiratory techniques) have demonstrated a reduction in the severity of disease. For these reasons, these techniques cannot be used as standard clinical practice for hospitalised patients with severe bronchiolitis. There is high quality evidence that forced expiratory techniques in severe patients do not improve their health status and can lead to severe adverse events. Slow passive expiratory techniques provide an immediate and transient relief in moderate patients without impact on duration. Future studies should test the potential effect of slow passive expiratory techniques in mild to moderate non-hospitalised patients and patients who are respiratory syncytial virus (RSV) positive. Also, they could explore the combination of chest physiotherapy with salbutamol or hypertonic saline.

Plain-language summary: The evidence is current to July 2015. This review has included 12 trials with a total of 1249 participants. By type of chest physiotherapy, five trials tested vibration and percussion techniques in 246 participants, three trials tested forced expiratory techniques in 624 participants, and four trials tested slow flow techniques in 375 participants. Vibration and percussion techniques produce a thorax (chest) oscillation by fast compression or percussion with the physiotherapist's hands. Neither manoeuvre was shown to improve the clinical scores of patients with acute bronchiolitis in the trials. These techniques did not show improvements in respiratory measurements, time on oxygen therapy or length of hospital stay. There were no data on time to recovery from acute bronchiolitis, use of bronchodilators or steroids, or parents' assessment of physiotherapy benefit. The trials included in this review did not present data on adverse effects related to the intervention, but the literature cites cases of relevant adverse effects such as rib fractures related to these techniques. Forced expiratory techniques consist of suddenly increasing the expiratory flow by compressing the thorax or the abdomen. In participants with severe bronchiolitis, such techniques failed to reduce time to recovery or time to clinical stability when compared to no physiotherapy. They also failed to improve clinical scores, oxygen saturation or respiratory rates except in mild to moderate bronchiolitis patients. There were no data on secondary outcomes such as duration of oxygen supplementation, length of hospital stay, or use of bronchodilators and steroids. Two studies reported no significant differences in parents' impression of the benefit of physiotherapy compared to controls. One of the trials reported a higher number of transient episodes of vomiting and respiratory instability after forced expiratory physiotherapy. This trial found no differences for bradycardias (decreases in heart rate), with and without desaturation (reduced oxygen levels in blood). Slow flow techniques consist of compressing the rib cage and the abdominal cavity gradually and gently from the mid-expiratory phase up to the end of exhalation. Slow flow techniques showed an overall lack of benefit on clinical scores of severity of the disease. However, in two trials they provided either a short-lived relief in terms of clinical scores or a decrease in the need for oxygen support in children with moderate bronchiolitis. There were no changes in length of hospital stay, use of bronchodilators or steroids. There were no data on changes in time to recovery, change in respiratory measurements, or parents' impression of physiotherapy benefit. No severe adverse events were reported in the trials. Vibration and percussion techniques are not recommended in routine practice in hospital settings due to a lack of benefit and risk of potential adverse events. There is high quality evidence that forced expiratory techniques in severe bronchiolitis present no clinical benefit, while being related to adverse effects such as vomiting, bradycardia with desaturation, or transient respiratory destabilisation. There is low quality evidence that suggests that slow flow techniques do not provide a clear overall benefit, but could provide some transient benefits in some children with bronchiolitis. Except for one trial, related to forced expiration, the included trials are at unclear or high risk of bias. The risk of bias of the trials and the imprecision of the estimates led to the low quality of evidence for the effect of slow flow techniques on clinical scores. Further trials are needed before reaching firm conclusions.