Successful conservative managements of extensive pneumatoceles in a preterm girl: A case report

Abstract

We describe a preterm girl with severe respiratory distress syndrome, which was managed with mechanical ventilation. She developed severe ventilator induced lung injury, causing extensive unilateral emphysema. CT-scan of the lungs corresponded with extensive pneumatoceles. She was managed conservatively, using neurally adjusted ventilatory assist, with success and was extubated on day of life 38. She was discharged home without any respiratory support at 39 weeks of postmenstrual age. Our case illustrates the ongoing risk of severe ventilator induced lung injury and highlights a unique injury pattern in a preterm newborn that was managed conservatively using neurally adjusted ventilatory assist with an excellent outcome.

Keywords

Respiratory distress syndrome ventilator induced lung injury pneumatoceles neurally adjusted ventilatory assist

1 Introduction

In preterm newborns, respiratory distress syndrome (RDS) is usually treated with respiratory support and surfactant therapy. For the most extremely premature infants there is often need for mechanical ventilation (MV) which is invasive and can potentially be harmful for lung development. As a consequence, ventilator induced lung injury remains an important issue in the respiratory care for very preterm infants with serious lung immaturity. In addition, we know that infectious complications can further damage the preterm lungs and increase the risk of bronchopulmonary dysplasia.

In this report, we describe a clinical case with severe lung damage resulting in extensive pneumatoceles. It highlights a unique injury pattern in a very preterm newborn that was managed conservatively with an excellent outcome. We aimed to illustrate the ongoing risk of severe ventilator induced lung injury in these smallest infants, however we hope that the excellent outcome in our case might reassure other clinicians and confirm them in the conservative treatment of these preterms.

2 Case report

A preterm girl was born at 25 weeks’ gestation, with a birth weight of 765 grams, by caesarean delivery for fetal distress associated with maternal pre-eclampsia. She had severe RDS necessitating intubation in the delivery room. She received surfactant at 30 minutes of age and was started on MV, initially on neurally adjusted ventilatory assist (NAVA) because of a good respiratory drive. However, at 48 hours of life, the ventilator conditions were changed to conventional MV because of respiratory insufficiency. She was supported with pressure regulated volume controlled (PRVC) ventilation with tidal volumes of 4–6 ml/kg and a positive end-expiratory pressure (PEEP) of 7 cm H₂O, adaptations were made based on blood gas analyses. Over the following days, weaning her from the ventilator was difficult because of oxygenation difficulties. On the ninth day of life we started low-dose dexamethasone treatment to facilitate extubation, and she was extubated on day 11 to non-invasive NAVA (NIV-NAVA) with level 1.0 and a PEEP of 6-7 cm H₂O (Fig. 1). After 4 days, she was reintubated because of severe apnea, due to a Staphylococcus aureus sepsis, and was started on antibiotics. She was again supported with PRVC ventilation, necessitating higher tidal volumes this time of 6-7 ml/kg and a PEEP of 6.5 cm H₂O. Weaning her ventilator conditions was difficult. From day 19 we noted unilateral severe emphysema on her chest X-ray, after which we opted to switch her ventilator settings to NAVA in an attempt to reduce mean airway pressure and stimulate her own breathing effort. We commenced this respiratory support using a level of 2 and kept the PEEP constant at 6.5 cm H₂O. CT-scan of the lungs showed extensive cystic dilatation of the affected bronchi in the lower left lobe with cardiomediastinal shift to the right. After this initial phase with rather high NAVA conditions, we gradually weaned the level and back-up ventilation conditions based on blood gas analyses and tracking records of her respiratory drive. She was extubated on day of life 38 and continued with non-invasive ventilatory support, initially using NIV-NAVA and then gradually weaning her to nCPAP and high-flow nasal cannula. We repeated a CT-scan at 37 weeks which was consistent with bronchopulmonary dysplasia (BPD), the cystic lesions had evolved into cord atelectasis with some loss of lung volume (Fig. 2). Despite the severity of the initial radiological image, she was managed conservatively. All respiratory support could be stopped at 38 weeks and she was discharged home without any respiratory support at 39 weeks. Her weight at discharge was 2704 grams. She is now corrected 6 months old, shows a nice catch-up of growth parameters and has not been hospitalized so far.

Fig.1

Timeline of the case report.

Fig.2

Imaging studies during hospitalisation. A: Chest X-ray on day 26. B: Lung CT on day 37. C: Chest X-ray on day 58. D: Lung CT on day 79.

3 Discussion

The radiological image illustrated by our case, corresponds with the presence of several pneumatoceles in the left lung in a preterm neonate that was treated with mechanical ventilation. Our report shows repetitive chest X-ray and CT-scan imaging of such extensive unilateral pneumatoceles, filling the entire left lung, and leading to an important cardiomediastinal shift.

Pneumatoceles are air-filled cystic lesions that develop within the lung parenchyma. In preterm infants, they are particularly associated with ventilator-induced lung injury [1, 2] and infections (especially Staphylococcus aureus sepsis or pneumonia) [3]. Most reports on neonatal pneumatoceles in the literature date from the 1970s and 1980s when more aggressive ventilation strategies had to be used for treating severe respiratory distress syndrome. They occur mostly unilaterally, but can be present in both lungs, and are often associated with other air leak syndromes. Their incidence has decreased significantly since surfactant replacement therapy became standard of care for preterm babies with RDS. However, up to 80% of these patients develop bronchopulmonary dysplasia and mortality also remains high, which seems due to overall lung immaturity in the population of preterms presenting with this type of lesions [4]. Therapeutic options range from conservative management with lung-protective ventilation strategies to unilateral lung intubation or even percutaneous drainage of the pneumatocele, as reported in more recent case reports of extensive cystic lesions [5, 6].

We managed our patient conservatively and tried to reduce the positive airway pressure, but after diagnosis of the extensive pneumatoceles changed ventilation strategy. We used neurally adjusted ventilatory assist (NAVA) to synchronize and proportionally support the patient’s own respiratory drive [7], and as such were able to reduce mean airway pressure quickly. The pneumatoceles resolved spontaneously and did not reoccur once she was extubated. NAVA is a relatively new type of ventilation used in preterm babies. It uses the electrical activity of the diaphragm to synchronize the infant’s own respiratory effort with mechanical ventilation. As such the ventilator delivers pressure synchronous to the baby’s breathing and proportionally to the patient’s own effort, often leading to a reduction in mean airway pressure [8]. In this case, we used NAVA as a rescue treatment because of the barotrauma related pneumatoceles, which led to a fast decrease in mean airway pressure, allowing for a slow regression of the pneumatoceles.

4 Conclusion

Our case highlights an unusual clinical presentation of a formerly more common condition in preterm infants with severe RDS. We were able to manage these extensive pneumatoceles that practically filled an entire lung, with conservative treatment and gentle respiratory support using NAVA. There was complete resolution of the cystic lesions and our patient was discharged home without any respiratory support before 40 weeks of corrected gestational age.

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