venovenous extracorporeal membrane oxygenation ( vv ecmo ) has been well described to manage acute respiratory distress syndrome ( ards ) .
the onset of ards in the setting of h1n1 influenza is often hyper - acute , requiring emergent ventilatory support and , in severe cases , ecmo cannulation . in the setting of emergent intubation ,
tracheal injury is a rare but catastrophic complication , occurring in 1 in 20,000 endotracheal intubations .
historically , urgent surgical intervention has been the mainstay of management of post - intubation tracheal injury . however , more recent reviews advocate a conservative approach , especially in patients who will require prolonged ventilation due to underlying pulmonary pathology [ 3 , 4 ] .
our case demonstrates successful management of concomitant tracheal injury and h1n1 influenza complicated by bacterial super - infection with vv ecmo supplemented by high - frequency oscillator ventilation ( hfov ) , prone positioning , and tube thoracostomy in an adult patient .
a 33 year - old previously healthy , morbidly obese ( body mass index 40 , body weight 98 kg , height 157 cm ) female presented to an outside emergency department with progressive dyspnea and malaise . in the emergency department , she rapidly developed acute hypoxic respiratory failure with bilateral infiltrates on chest x - ray ( figure 1a ) .
post - intubation chest x - ray showed the endotracheal tube in the right main stem bronchus ( figure 1b ) , requiring adjustment ( figure 1c ) .
she remained hypoxic and was transferred to a tertiary center for ards management . at arrival , she was hypoxic ( arterial blood gas was ph 7.18 , paco2 58 , pao2 52 , saturation 78% ) , despite fractional inspiratory oxygen ( fio2 ) of 100% , tidal volume ( tv ) 600 ml , respiratory rate of 20 positive end expiratory pressure ( peep ) of 20 mm h2o with paralysis and epoprostenol ( 50 ng / kg / min ) support
. failed medical management necessitated urgent vv ecmo using a bi - caval dual lumen cannula ( maquet , rastatt , germany ) via the right internal jugular vein , after we obtained consent from her family .
her oxygenation improved ( ph 7.35 , paco2 31 , pao2 176 and saturation > 99% ) with vv ecmo flow of 4 lpm , sweep of 6 lpm and fio2 100% .
the patient was found to be positive for h1n1 influenza with super imposed methicillin - sensitive staphylococcus aureus ( mssa ) pneumonia ; tamiflu ( 75 mg q12 hours ) and broad - spectrum antibiotic coverage with vancomycin ( 1.5 gram q12 hours , titrate by the rough level 15 - 20 mg / l ) and piperacillin / tazobactam ( 3.375 gram q8 hours ) were initiated .
ventilator settings were changed from conventional mode ( tv 600 ml , rate 20 , fio2 100% , peep 20 ) to ardsnet protocol , with 300cc tv ( tv=4 - 6 ml / kg , based on an ideal body weight of 55 kg ) , respiratory rate 10 , and fio2 of 100% with peep 10 for lung protection .
peak airway pressure and mean airway pressure remained elevated ( 58 cm h2o and 15 cm h2o respectively ) .
post - ecmo chest x - ray showed a loculated lower left pneumothorax , treated immediately with bedside thoracostomy tube placement ( figure 1d ) .
post intubation x - ray shows endotracheal tube in the right main stem bronchus ( 1b ) .
after repositioning the endotracheal tube , there is the progression of the bilateral infiltrations ( 1c ) .
post ecmo cannulation at arrival to our facility , there is a large loculated pneumothorax in the left thorax ( 1d ) .
bronchoscopy ( figure 2 ) showed a 3 - 4 cm injury of the posterior membranous trachea approximately 1 cm above the carina , confirmed by computed tomography ( figure 3 ) .
axial ( a ) and sagittal ( b ) computed tomography images demonstrating 3 - 4 cm defect in posterior membranous trachea ( arrow ) .
thoracic surgery was consulted for evaluation of the trachea injury , but the patient was deemed a poor surgical candidate due to severe ards requiring ecmo with high positive pressure ventilation . the patient began to show failure of ardsnet   conventional ventilation ( tv = 220 - 330 cc peep 10 ) with worsening air leak around the endotracheal tube despite of inflation of the cuff , air leak from the chest tube , pneumothorax , pneumomediastinum , and co2 retention on ardsnet ventilation ( abg : ph 7.29 , paco2 59 , pao2 147 and saturation 99% ) ; high frequency oscillatory ventilation ( hfov , setting mean airway pressure 18 cm h2o , amplitude ( p ) 75 cm h2o . frequency 5 hz , fio2 50% . ) was initiated .
pneumothorax , pneumomediastinum and chest tube air leak improved , as well as the abg was improved with the hfov ( ph 7.37 , paco2 39 , pao2 116 , saturation 99% ) . the tracheal tear was evaluated daily by bronchoscopy with airway lavage to prevent mucous accumulation . with pneumothorax , pneumomediastinum , and
air leak from the chest tube stabilized , on ecmo day 14 and 11 total days of hfov support , the patient was successfully weaned back to ardsnet protocol ventilation from hfov . with ongoing poor lung recruitment and progression of pulmonary infiltrate ,
the patient was transitioned to prone position ventilation , using the automated rotoprone system ( kci , san antonio , tx ) .
in prone position , abg improved to ph 7.46 , paco2 34 , pao2 105 , saturation 98% from ph 7.41 , paco2 43 , pao2 67 , saturation 93% while in supine . per protocol ,
the patient was continually rotated to at least 40 degrees for a minimum of 18 hours per day with a maximum prone interval of 3 hours and 15 minutes , interrupted with 45 minutes periods of supine positioning for general nursing care and to minimize facial edema .
the patient s sedation was maintained with ketamine , fentanyl , and midazolam and she was paralyzed with rocuronium .
enteral nutrition was continued while the patient was paralyzed through a post - pyloric nasal - duodenal tube to minimize risk for aspiration . the patient s pulmonary status improved with prone positioning after 6 days and she was successfully weaned and decannulated from vv ecmo on day 20 . at the time of decannulation , bronchoscopy showed improvement of the tracheal injury and esophagogastroscopy confirmed no communication with the esophagus . on day 5 post - decannulation ,
the patient had a tracheostomy and gastrostomy tube placed for long - term ventilation weaning . on day
20 post decannulation , she was tolerating tracheostomy collar and transferred out of the intensive care unit to the ward . on day 28 post - decannulation ,
the patient underwent swallow evaluation and was cleared for a diet , tolerating a passy - muir valve ( passy - muir , irvine , ca ) .
the patient worked well with physical therapy , ambulating with assistance and was transferred to a rehabilitation facility on post decannulation day 48 .
the data presented in this paper was collected under approval from thomas jefferson university internal review board .
concurrent acute hypoxic respiratory failure secondary to infection with h1n1 influenza and post - intubation tracheal injury pose a difficult management dilemma due to the requirement for long term positive pressure ventilation . during endotracheal intubation
, superficial mucosal tears occur in 18% of patients ; however , full thickness post - intubation tracheal injury like this case is rare .
patient risk factors for post - intubation tracheal injury include female gender , short stature (  160 cm tall ) , difficult airway anatomy , underlying connective tissue disorder and mechanical risk factors include use of rigid stylet , inadequate intubation tube size , cuff over - inflation , emergent intubation , and intubation by non - anesthesiologists .
emergency intubation and delayed diagnosis have been identified as independent risk factors for mortality after post - intubation tracheal injury .
initial presentation is most often characterized by subcutaneous emphysema , pneumothorax , persistent air leak and hemoptysis - less commonly pneumomediastinum , angina , hypotension and shock [ 2 , 4 ] .
ecmo management for isolated tracheal injury has been previously described , in 10 published reports - 4 pediatric patients and 6 adults ( table 1 ) .
ards = acute respiratory distress syndrome ; ecmo = extracorporeal membrane oxygenation ; na = not available ; va = venoarterial ; vv = venovenous ; hfov = high frequency oscillatory ventilation .
early reports utilized veno - arterial cannulation , but the majority of patients had isolated pulmonary failure secondary to tracheal tear , requiring only vv ecmo .
the majority of iatrogenic injuries resulted in a distinct longitudinal injury to the membranous portion of the trachea , as opposed to blunt chest trauma that resulted in transverse injury with irregular borders .
blunt chest trauma usually required surgical repair , likely due to the nature of tracheal injury especially if anticoagulation and ecmo is required for support [ 7 , 9,10,11,12 ] . in these papers
although there is likely publication bias , the results from these isolated reports show ecmo to be a promising strategy for tracheal injury with potential for positive outcomes .
retrospective review has shown a two - fold increase in mortality for surgical management of tracheal injuries detected outside the operating room .
conservative management strategies include low tidal volume ventilation , permissive hypercapnia , endotracheal tube fixation in the distal trachea , double lumen intubation , daily bronchoscopy , hfov , and even ecmo , as in our case .
however , current strategies have shifted to reserve surgery only for cases that have failed conservative management - signified by worsening mechanical ventilation requirements , uncontrolled air leak , and active endobronchial bleeding [ 3 , 4 ] .
conservative therapy is particularly successful in small injuries , less than 2 cm , with minimal non - progressive symptoms , and no air leakage on spontaneous breathing .
vv ecmo provides oxygenation and ventilation allowing for minimal ventilatory support and reduced associated baro- and volu - trauma to the injured bronchial tree .
failed oxygenation on vv ecmo may require transition to va ecmo in order to fully rest the lungs and bronchial tree . in our case ,
va ecmo was not ideal due concern to increased infectious risk with femoral cannulation in an morbidly obese patient . in combination with vv ecmo
, rescue ventilation therapies may further minimize barotrauma to the injured trachea [ 6 , 11 ] .
important adjunct therapies to aid in the healing of the tracheal injury in our patient were prone position ventilation and high frequency oscillatory ventilation .
a recent randomized control trial showed the benefit of prone positioning on survival in ards , but evidence for use with hfov and concomitant tracheal injury is limited .
tracheal injury , especially in the setting of underlying severe lung injury , is rare and has a high mortality rate .
the management has evolved over time , with a movement toward conservative management due to the high morbidity and mortality associated with surgical repair . here
we present a conservative management strategy that incorporates the newest advances in pulmonary critical care , and the first report of successful management of an adult patient with concomitant ards , mssa super - infection and post - intubation tracheal injury with vv ecmo , hfov and prone position ventilation .
 tracheal injury is a rare but highly morbid complication of endotracheal intubation . 
 recent reviews have advocated conservative management of these injuries without operative intervention . 
 extracorporeal membrane oxygenation may be a useful tool in non - operative management of tracheal injury in the setting of severe respiratory failure and need for prolonged intubation . 
 we present a morbidly obese 33 year - old - female with h1n1 influenza pneumonia complicated by acute respiratory distress syndrome and bacterial super - infection who sustained a post - intubation tracheal injury . 
 concomitant tracheal injury and acute lung injury pose a difficult ventilation dilemma . 
 this patient was successfully managed by venovenous extracorporeal membrane oxygenation , high frequency oscillator ventilation , proning position and tube thoracostomy . 
 the venovenous extracorporeal membrane oxygenation and ventilator management were essential for this patient s recovery . 
Introduction
Case Report
Discussion