Independent Lung Ventilation as a Means to Facilitate Extracorporeal Membrane Oxygenation Decannulation

An 11-Year-Old Girl with Life-threatening Pneumonia Independent Lung Ventilation as a Means to Facilitate Extracorporeal Membrane Oxygenation Decannulation Marlina E. Lovett 1 and Todd J. Karsies 1,2 1 Division of Critical Care Medicine, Nationwide Children s Hospital, Columbus, Ohio; and 2 Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio ORCID ID: 0000-0002-9531-9481 (M.E.L.). Abstract Independent lung ventilation is an infrequently used ventilation strategy in the pediatric intensive care unit but can be beneficial in unique patient subsets, such as patients who have asymmetric pulmonary pathology. Independent lung ventilation allows for the independent delivery of the appropriate effective tidal volume to each lung on the basis of individual compliance and pathology. In theory, it may help avoid alveolar overdistension and ventilator-induced lung injury in the nondiseased lung. In addition, it allows for targeted interventions. Here, we describe a child with unilateral lung disease requiring veno-venous extracorporeal membrane oxygenation who rapidly improved, allowing decannulation within 24 hours, after the application of independent lung ventilation and unilateral surfactant administration. Keywords: pediatric critical care; respiratory failure; extracorporeal technology; dual-lumen endotracheal tube (Received in original form March 24, 2016; accepted in final form June 11, 2016 ) Author Contributions: M.E.L. and T.J.K.: report conception, manuscript revision, and approval of the final draft; M.E.L: initial manuscript preparation. Correspondence and requests for reprints should be addressed to Marlina E. Lovett, M.D., Division of Critical Care Medicine, Nationwide Children s Hospital, 700 Children s Drive, Columbus, OH 43205. E-mail: marlina.lovett@nationwidechildrens.org Ann Am Thorac Soc Vol 13, No 10, pp 1789 1793, Oct 2016 Copyright 2016 by the American Thoracic Society DOI: 10.1513/AnnalsATS.201603-210BC Internet address: www.atsjournals.org Independent lung ventilation is an infrequently used ventilation strategy in the pediatric intensive care unit (PICU). This strategy is rarely used largely because of the pediatric intensivist s lack of experience with this modality and because of patient size limitations. Independent lung ventilation can help compensate for the varied lung compliance in the healthy vs. the diseased lung and attempts to deliver the appropriate effective tidal volume to the poorly compliant lung segments while avoiding alveolar overdistension of the compliant segments. The literature supporting the use of independent lung ventilation is derived predominantly from patients undergoing thoracic surgery in the operating room setting (1, 2). Here, we describe a patient with severe hypoxemic respiratory failure in the setting of necrotizing pneumonia secondary to methicillin-resistant Staphylococcus aureus and influenza A requiring veno-venous extracorporeal membrane oxygenation (ECMO), who rapidly improved with the use of independent lung ventilation and surfactant. This case report was accepted as a poster at the 45th Critical Care Congress, Society of Critical Care Medicine, February 2016 in Orlando, Florida. Case Report An 11-year-old, previously healthy girl presented to our tertiary care pediatric hospital s emergency department with 2 days of fever, cough, and respiratory distress. Initially, she was placed on bilevel positive airway pressure ventilation via face mask. A chest radiograph showed near-complete opacification of the right hemithorax (Figure 1). Because of persistent hypoxemia, she required endotracheal intubation within 90 minutes of arrival. During her intubation, the airway was noted to be inflamed, with evidence of purulence. Upon arrival to the PICU, the patient experienced continued hypoxemia (80% oxygen saturation) despite the following ventilator settings: synchronized intermittent-mandatory ventilation pressure control, peak inspiratory pressure of 32 cm H 2 O, positive end-expiratory pressure of 12 cm H 2 O, and FI O2 of 100%. High-frequency oscillatory ventilation and inhaled nitric oxide were briefly tried because of persistent hypoxia. However, with an oxygenation index of 60, the patient was placed ultimately on veno-venous ECMO within Lovett and Karsies: Independent Lung Ventilation and ECMO 1789

her diseased lung improved markedly and she began to tolerate ventilator weans (Figure 3 and Table 1). She was decannulated from ECMO within 24 hours (Day 6) after the initiation of independent lung ventilation and was extubated 48 hours after decannulation (Day 8). She was transferred out of the PICU on Day 11 and survived to discharge (Day 23). Figure 1. Initial chest X-ray obtained on arrival at the hospital. 8 hours of PICU arrival. She was diagnosed with necrotizing pneumonia secondary to methicillin-resistant Staphylococcus aureus as well as influenza A. While on ECMO, her ventilator settings were as follows: airway pressure release ventilation (P high 20/P low 10 cm H 2 O, T high 6/T low 0.4 s). After 4 days of airway pressure release ventilation and appropriate antimicrobial and antiviral therapy, there was no significant improvement in lung compliance. Given persistent and minimally changed unilateral opacification of the right hemithorax, the treatment team decided to institute independent lung ventilation with the hope of recruiting the diseased lung. Therefore, she underwent bronchoscopy with a planned endotracheal tube change to a dual-lumen endotracheal tube. Bronchoscopy was notable for friable mucosa and purulent secretions. Her 6.0 endotracheal tube was transitioned to a 32- French, left-sided, dual-lumen endotracheal tube (Figure 2). She subsequently underwent unilateral surfactant instillation to the diseased right lung. Independent lung ventilation was initiated on Hospital Day 5 with the use of two Avea ventilators (CareFusion; BD Worldwide, San Diego, CA) (settings are given in Table 1). An external cable was used to synchronize the ventilators and ensure delivery of the same respiratory rate, creating a master ventilator and a slave ventilator. At the initiation of independent lung ventilation while trying to recruit the right lung using the ventilator settings noted in Table 1, the mean airway pressure of her left lung was 13 cm H 2 O (effective tidal volume of 3.1 ml/kg) in contrast to the diseased right lung with a mean airway pressure of 20 cm H 2 O (effective tidal volume of 1.4 ml/kg). Within 12 hours of initiation, both aeration and compliance in Tracheal lumen Trachea Discussion Figure 2. Schematic of the dual-lumen endotracheal tube (ETT). Asymmetric pulmonary pathology presents a unique, but not uncommon, challenge to the intensivist who must rerecruit an injured or diseased lung while limiting overdistension and secondary injury to the healthy lung. With this pathology, use of a conventional ventilator mode may not be ideal because the application of an equal driving pressure to both lungs with markedly different compliance will lead to overdistension and ventilator-induced lung injury in the compliant lung and/or potentially inadequate ventilation and atelectrauma in the poorly compliant lung. Dual-lumen ETT Bronchial lumen 1790 AnnalsATS Volume 13 Number 10 October 2016

Table 1. Ventilator settings during ILV ILV Time Left Lung Right Lung Mode PEEP Set TV PIP Eff TV Mode PEEP PIP Eff TV Initiation PRVC-AC 8 3.6 26 3.1 Pressure-AC 14 34 1.4 12 h PRVC-AC 8 3.6 25 3.2 Pressure-AC 14 30 2.3 24 h PRVC-AC 8 3.6 24 3.6 Pressure-AC 14 30 2.5 48 h PRVC-AC 8 3.2 23 3.3 Pressure-AC 9 26 3.1 72 h CPAP/PS PEEP 6/PS 6 CPAP/PS PEEP 6/PS 6 Definition of abbreviations: CPAP = continuous positive airway pressure; Eff TV = effective tidal volume; ILV = independent lung ventilation; PEEP = positive end-expiratory pressure; PIP = peak inspiratory pressure; PRVC-AC = pressure-regulated volume control assist control; PS = pressure support; TV = tidal volume. All pressures are listed in cm H 2 O. Independent lung ventilation is a potential solution to this specific challenge. The necessity of either anatomic or physiologic lung separation is an indication for independent lung ventilation. This technique has been used for anatomic separation when trying to isolate one lung from injurious contaminants (such as in the case of massive hemoptysis), whole lung lavage, and thoracic surgery including pneumonectomy/ lobectomy (2, 3). Indications for physiologic separation pertinent to the critical care physician include unilateral parenchymal disease (aspiration, pulmonary contusion, pneumonia), unilateral atelectasis, postoperative complications of single lung transplant including pulmonary edema, unilateral pulmonary hemorrhage, bronchopleural fistula, massive unilateral pulmonary embolism, and though controversial, potentially severe bilateral lung disease (4 8). A direct benefit of using independent lung ventilation is its ability to deliver a different driving pressure to each lung on the basis of its individual compliance. Instead of targeting an effective tidal volume of 6 8 ml/kg, one aims to deliver half of that effective tidal volume to each individual lung, approximately 3 ml/kg per lung (9). With the use of independent lung ventilation, it is possible to ventilate each lung with a different mode. For example, in this case, the right lung was ventilated using pressure assist control, whereas the left was ventilated using pressure regulated volume control. Indeed, the use of high-frequency oscillatory ventilation with independent lung ventilation has even been reported (10, 11). It is possible to provide synchronous or asynchronous independent lung ventilation. Synchronization is performed using an external cable to synchronize the respiratory cycle between the two ventilators, but it still allows the physician to choose different ventilator modes and settings. Asynchronous ventilation allows the ventilators to deliver support with independent respiratory cycles, although this strategy may require deeper sedation or paralysis to facilitate patient ventilator interaction. The delivery of compliancespecific ventilation may allow the duration of mechanical ventilation to be shortened, but this requires further investigation. Although there are advantages to using independent lung ventilation, there are also technical challenges. Optimal placement of the dual-lumen endotracheal tube frequently requires direct visualization, typically using a flexible bronchoscope. Because precise positioning of the duallumen endotracheal tube is crucial, if the tube becomes dislodged, it does have the potential to obstruct the bronchus and would require repositioning using direct visualization. Therefore, when independent lung ventilation is performed, deep sedation and paralysis may be required. In addition to the logistics of placing the endotracheal tube, it has been noted that the dual lumens (bronchial and tracheal) are narrower than the traditional endotracheal tube and could be more prone to obstruction (4). Furthermore, suctioning of the lumens requires a longer suction catheter. Complications associated with the use of independent lung ventilation include the following: pneumothorax, pneumomediastinum, bronchial ischemia, and bronchial stenosis. Bronchial ischemia and stenosis may occur due to the high pressure generated by the cuff of the bronchial lumen. Therefore, whenever moving the patient, cuff deflation is recommended to avoid airway trauma (3). A contraindication to the use of independent lung ventilation would include the inability to confirm proper placement of the duallumen endotracheal tube. Although independent lung ventilation is used frequently in the operating room, the literature supporting its use in the PICU is sparse. In general, the use of independent lung ventilation in the PICU is limited because of the size of the patient s airway. The smallest commercially available dual-lumen endotracheal tube at most centers in the United States is a 26- or 28-French, which would be appropriate for an 8- to 10-year-old, effectively limiting the possibility of use in patients younger than 8 years of age. However, there are smaller sizes available outside the United States, and independent lung ventilation has been performed in the neonatal population through the use of two uncuffed endotracheal tubes (9). In addition, both awareness and experience with independent lung ventilation are limited in the PICU setting. Independent lung ventilation was not instituted earlier in this patient s course because coordination among anesthesiology, pulmonology, and the PICU was required for tube placement; furthermore, additional education was required for bedside providers, as this was the first time in which our PICU employed this ventilator strategy. National data from the Extracorporeal Life Support Organization Registry (12) indicates that the mean ECMO duration for pediatric viral and bacterial pneumonia is 317 and 286 hours (65% and 59% survival), respectively. In 2014, the mean pediatric respiratory ECMO course was 258 hours. At our institution, the mean ECMO duration was 188 hours. This patient had Lovett and Karsies: Independent Lung Ventilation and ECMO 1791

Figure 3. (A) Chest X-ray (CXR) after extracorporeal membrane oxygenation cannulation. (B) CXR immediately before bronchoscopy/endotracheal tube (ETT) change. (C) CXR immediately after dual-lumen ETT placement. (D) CXR 12 hours after dual-lumen ETT placement. an ECMO duration of 117 hours. Because this patient s severe unilateral lung disease did not improve after several days of appropriate antimicrobial therapy, and there was a desire to achieve the shortest ECMO duration possible, independent lung ventilation was instituted with the goal of effectively recruiting the poorly compliant lung while preventing harm to the healthy lung. Although this patient s positive outcome was likely secondary to multiple factors, we present the unique case of using independent lung ventilation to achieve diseased lung recruitment more quickly and with a shorter overall ECMO duration to avoid unnecessary comorbidities (13, 14). Prolonged ECMO courses have been associated with both morbidity and mortality; therefore, every effort was made, including the use of bronchoscopy and surfactant, to improve this patient s respiratory system compliance to ultimately shorten the ECMO duration (15, 16). Independent lung ventilation allows for targeted interventions such as therapeutic bronchoscopy. The use of independent lung ventilation provided protection to the nondiseased lung from high airway pressures while surfactant was instilled into the diseased lung. As surfactant decreases alveolar surface tension, this targeted application allowed for the maintenance of functional residual capacity and the prevention of further atelectasis (16). With the use of independent lung ventilation and surfactant, this approach targeted therapy to the diseased lung and helped avoid overdistension and barotrauma to the healthy lung. In addition, ventilationperfusion mismatch was improved. These therapies were associated with rapid decannulation from ECMO (,24 h). We attribute this patient s substantially shorter ECMO duration to the use of independent lung ventilation. The complications and comorbidities from ECMO, including significant intracranial hemorrhage, infection, and death, can be catastrophic (13 15, 17). Not only are such ECMO complications significant to the patient, but they are significant to the health care system in terms of length of stay and days spent on the ventilator. This case illustrates the successful use of independent lung ventilation, and, to the best of our knowledge, this is the first report of a pediatric patient with such rapid decannulation from ECMO after the initiation of independent lung ventilation. The literature supporting the use of independent lung ventilation is mostly limited to case reports. Toadvancetheuseofthistechniquein pediatrics, additional manufacturer sizes are needed to accommodate smaller patients. Further research is needed to investigate the complications associated with the use of the dual-lumen endotracheal tube and to evaluate situations in which the technique could be beneficial to the critical care physician. In conclusion, if instituted early, independent lung ventilation may warrant consideration in the management of acute, severe, unilateral lung disease to facilitate lung recruitment and to potentially avoid ECMO. n Author disclosures are available with the text of this article at www.atsjournals.org. Acknowledgment: The authors thank Tom Heater, R.R.T., for the education that you provided to the bedside team and for assistance with the implementation of independent lung ventilation. They also thank Melissa Robinson, R.N., for her assistance with obtaining ECMO data. 1792 AnnalsATS Volume 13 Number 10 October 2016

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