Original Article
Atelectasis prevention during anaesthesia using high-flow nasal cannula therapy: A paediatric randomised trial using MRI images

https://doi.org/10.1016/j.accpm.2020.08.009Get rights and content

Abstract

Background

Atelectasis frequently occurs early on during anaesthesia in children. We hypothesised that positive expiratory pressure (PEP) generated via high-flow nasal cannula (HFNC) could prevent atelectasis in non-intubated children under general anaesthesia. 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.

Methods

A prospective single-centre, single-blind, randomised trial was conducted in a tertiary hospital from November 2018 through May 2019. The trial subjects were infants and children between six months and six years of age who required anaesthesia for an MRI. The children were randomised to receive sevoflurane for maintenance of anaesthesia either via a classic face bag-mask or by HFNC. The atelectasis volume was measured from thoracic MRI images. The judgement criterion was the ratio of the atelectasis volume to the lung volume.

Results

Of a trial group of 42 patients, 21 received anaesthesia via a face bag-mask and 21 via HFNC. After three patients were excluded for technical issues, the data for 39 patients were analysed. The atelectasis volume to the lung volume ratio in the HFNC group was significantly smaller than the ratio for the face bag-mask group (1.6% vs 6.8%, respectively; p = 0.002).

Conclusion

HFNC was associated with a lower atelectasis lung ratio compared to using a face bag-mask during anaesthesia for children maintained with spontaneous ventilation. Registered on Clinicaltrials.gov: NCT 03592589

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).

References (28)

  • M.A. Sargent et al.

    Atelectasis on pediatric chest CT: comparison of sedation techniques

    Pediatr Radiol

    (1999)
  • G. Lutterbey et al.

    Atelectasis in children undergoing either propofol infusion or positive pressure ventilation anesthesia for magnetic resonance imaging

    Paediatr Anaesth

    (2007)
  • G. Serafini et al.

    Pulmonary atelectasis during paediatric anaesthesia: CT scan evaluation and effect of positive endexpiratory pressure (PEEP)

    Paediatr Anaesth

    (1999)
  • H. Lei et al.

    Serious airway-related adverse events with sevoflurane anesthesia via facemask for magnetic resonance imaging in 7129 pediatric patients: a retrospective study

    Paediatr Anaesth

    (2019)
  • View full text