Original ArticleAtelectasis prevention during anaesthesia using high-flow nasal cannula therapy: A paediatric randomised trial using MRI images
Introduction
Atelectasis and poorly ventilated lung areas may appear during general anaesthesia in adults and children [1]. A collapsed lung is easily resolved after a minor surgical procedure in children without comorbidities. However, atelectasis may persist in high-risk children after complex surgery. Atelectasis impairs lung oxygenation, which may lead to complications such as pneumonia, a need for re-intubation, and postoperative respiratory failure [2], [3], [4].
Anaesthesia-induced atelectasis has been reported during general anaesthesia in 64% and 100% of infants who were ventilated with and without positive end-expiratory pressure PEP, respectively [5], [6], [7], [8], [9]. Atelectasis frequently occurs early during sedation; in one study, 82% of children being anaesthetised and spontaneously ventilated for MRIs experienced atelectasis after 10 min [8].
There is no established prevention strategy for atelectasis, although PEP is usually applied to keep the lungs open. In children undergoing general anaesthesia for an MRI, using PEP reduced atelectasis in intubated patients [8], [9]. However, there is no evidence that a non-invasive technique can be efficient in preventing atelectasis during anaesthesia with spontaneous ventilation. Like many other teams, we have been practicing routine inhalation anaesthesia under spontaneous ventilation for MRIs [10], [11], [12]. For many years, we have been using a face mask-bag for delivering sevoflurane in MRIs in children, and we have regularly observed atelectasis when chest images were taken.
Therefore, we decided to perform a clinical study, without direct individual benefit, to test the effectiveness of spontaneous ventilation PEP in preventing atelectasis. Several non-invasive techniques are available to obtain PEP. A simple and safe way is the high-flow nasal cannula (HFNC) [13]. We chose HFNC, as it is relatively easy to implement in a setting where other techniques, such as continuous positive airway pressure are impossible to implement. To the best of our knowledge, the efficacy of HFNC in preventing atelectasis during anaesthesia in non-intubated patients has not been studied.
HFNC is defined as the administration of a heated, humidified, and blended air/oxygen mixture via nasal cannula at rates of 2 l/kg/min. [14] These high-flow rates generate levels of positive pressure in the upper airways, which is not usually measured (4 to 6 mmHg) [15], [16].
HFNC serves different purposes in different age groups [17]: in preterm infants, it is used in respiratory distress and for respiratory support after extubation [18]; in infants, it is used for the treatment of bronchiolitis [19]. Its use in adults focuses on hypoxaemic respiratory failure in intensive care patients and on oxygenation improvement during intubation [20], [21]. Also, HFNC extends the safe apnoea time of adults undergoing laryngotracheal surgery and of children undergoing laryngeal surgery [22], [23], [24].
We hypothesised that HFNC could prevent atelectasis in non-intubated children under general anaesthesia. We suggest that this is due to PEP. The objective was to compare the volume of atelectasis present in patients treated via HFNC to that of patients treated via a face bag-mask without PEP. The outcome used for this comparison was the ratio of the atelectasis volume to the total pulmonary volume, with both volumes being measured from MRI images.
Section snippets
Study design
This prospective, single-centre, single-blind, randomised trial was registered on Clinicaltrials.gov (NCT 03592589).
Ethical approval for this study (No. IRB IORG0008367/ID RCB: 2017-A02240-53) was provided by the Ethical Committee of Ile de France 1, on the 15th of May 2018.
Patient selection criteria
Eligible participants were children between six months and six years of age who required general anaesthesia for MRIs during the period between November 2018 and May 2019. Any prospective subjects with an American Society of
Results
This study took place from November 2018 to May 2019 in a tertiary teaching hospital. As a first step, 59 patients undergoing general anaesthesia for MRIs were assessed for eligibility.
Forty-two patients were enrolled in the study, 21 in each analysis group. After randomisation, three patients were excluded from the study: two because there was no thoracic image available and the third because of a tracheostomy that represent an exclusion criterion (Fig. 2). Thus, the final trial group
Discussion
The main finding of this study was that HFNC use significantly diminished lung atelectasis during anaesthesia in spontaneously breathing children under six years of age, thereby confirming our hypothesis.
In our population, using HFNC in spontaneous breathing during general anaesthesia kept the lungs open. We suggest that this is due to PEP.
The atelectasis frequency in the face bag-mask group was 90%, which is similar to the 82% found in the sole study on MRI anaesthesia in spontaneously
Conclusion
In the studied population, HFNC was effective in preventing atelectasis in children during spontaneous-breathing general anaesthesia. This study provides real-time anatomical proof of the efficiency of HFNC in preventing atelectasis. Further research is needed to confirm these results with different populations.
Presentation of preliminary data
None declared.
Ethical approval
Ethical approval for this study (No. IRB IORG0008367/ID RCB: 2017-A02240-53) was provided by the Ethical Committee of Ile de France 1, on the 15th of May 2018.
Disclosure of interest
None declared.
Funding
Assistance with the article: none declared.
Financial support was received from the French Society of Anaesthesia and Critical Care (SFAR: €10.000) and the Research department of the Assistance Publique Hôpitaux de Marseille (AP-HM: €17.000).
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