Extracorporeal Membrane Oxygenation for Traumatic Acute Respiratory Distress Syndrome in a Child

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1 J Med Sci 2004;24(6): Copyright 2004 JMS ChihHsien Lee, et al. Extracorporeal Membrane Oxygenation for Traumatic Acute Respiratory Distress Syndrome in a Child ChihHsien Lee, YiTing Tsai, ChienSung Tsai, and GuoJieng Hong * Division of Cardiovascular Surgery, Department of Surgery, TriService General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China Acute respiratory distress syndrome (ARDS) represents acute and rapidly progressive bilateral pulmonary infiltrates, which present on chest radiography. Although conventional mechanical ventilation is used, oxygen toxicity and ventilatorinduced injury have increased mortality rates for pediatric patients by 8489 % 1. Trauma has been responsible for ARDS in only one fourth of patients treated with extracorporeal membrane oxygenation (ECMO) 2. The management of severe pulmonary contusions in trauma patients with multiple injuries can be extremely challenging for clinicians 3. ECMO is an alternative supportive therapy for severe ARDS. The application of ECMO to children achieved a survival rate of 50% in an otherwise nonsalvageable group of patients 1,46. The advantage of ECMO is that it allows blood oxygenation at a far lower FiO 2, lower positive endexpiratory pressure and peak inspiratory pressure, and decreases the risk of barotrauma and oxygen toxicity. We report an 8yearold boy who had been involved in a highspeed car crash, sustaining left kidney laceration grade V. Traumatic ARDS was noted during postoperative days 2 and 3. Because no causal therapy is available for ARDS, therapy is only supportive. When conventional treatment modalities fail, the patient may be a candidate for ECMO. ECMO with heparinbonded circuitry offers supplemental capability while the primary injuries are being evaluated and treated. Our patient recovered and his other symptoms improved without complications within a 10month followup period. Key words: ECMO, traumatic ARDS INTRODUCTION As early as 1945, physicians recognized a threatening clinical syndrome previously known as adult respiratory distress syndrome 4. Since its introduction in the early 1970s, extracorporeal membrane oxygenation (ECMO) has received varying support 2. A simplified portable ECMO apparatus with percutaneous cannulas became commercially available in the 1980s 7, and ECMO has been used worldwide since the late 1980s 2. Although conventional mechanical ventilation is used, the mortality rate of acute respiratory distress syndrome (ARDS) is greater than % 1,4. ECMO may provide an alternative therapeutic method for treating traumatic ARDS when conventional Received: February 12, 2004; Revised: April 5, 2004; Accepted: April 16, * Corresponding author: GuoJieng Hong, Division of Cardiovascular Surgery, Department of Surgery, TriService General Hospital, 3, ChengKung Road Section 2, Taipei 114, Taiwan, Republic of China. Tel: ext 88058; Fax: ; DOC20386@mail. ndmctsgh.edu.tw treatment modalities fail. ECMO can relieve the injured lungs by reducing the mechanical ventilatory requirements to maintain adequate gas exchange, allowing almost complete lung rest from this stress and maximal recovery during this time. By decreasing the mechanical stress, these adjuncts to ventilation may result in less ventilatorinduced injury. ECMO has been used for the treatment of severe respiratory distress in the pediatric population with an overall survival rate internationally of more than 50% 1,46. ECMO can buy valuable time until the surgeon discovers the exact nature and severity of the patient s injuries 7. CASE REPORT An 8yearold boy was involved in a highspeed car crash in which he was thrown from a bicycle. Initially, he was taken to a hospital where primary examination and resuscitation was begun. Blunt abdominal injury with traumatic renal laceration, left grade V, was diagnosed. Because no intensive care unit (ICU) bed was available, he was transferred to our hospital for further evaluation and treatment. No other associated injury was found and congenital hypoplasia of the right kidney was identified after further examination. 333

2 ECMO for traumatic ARDS in a child SVC: superior vena cava; IVC: inferior vena cava. Fig. 1 Chest Xray shows traumatic ARDS on postoperative day 3. Fig. 2 Venovenous extracorporeal membrane oxygenation setting. Upon physical examination, he presented with an oral temperature of 36.4 o C, pulse rate of 91 beats/min, respiratory rate of 20/min, and blood pressure of 110/80 mmhg. He was awake but agitated. His conjunctiva were pale; the chest was clear breathing sound, bilateral; the abdomen was soft and ovoid in shape, with diffuse tenderness over the whole abdomen and rebounding tenderness over the left abdomen; abdominal distension and decreased bowel sound were also noted. No focal neurological deficits were noted. Others features were unremarkable. Laboratory tests were notable for a hemoglobin concentration of 12.0 g/dl, a leukocyte count of /μl, 91.9% neutrophils, 5.9% lymphocytes, and a platelet count of /μl. The ratio of patient prothrombin time to the control value was 12.2/11.5 s and the international normalized ratio was The activated partial thromboplastin time was 24.9/ 29.7 s. Electrolyte, routine urine, and liver function tests were all normal. An enhanced computed tomography scan of the abdomen revealed traumatic laceration of the left kidney, grade V, with fluid accumulation in the left perirenal space and atrophy of the right kidney. An emergency exploratory laparotomy through a midline abdominal incision was performed and the left kidney was repaired immediately. During the operation, blood loss was 900 ml, and a transfusion of 3 units of whole blood was performed at the same time. Pulmonary function deteriorated progressively during postoperative days 2 and 3. The patient s peripheral oxygen saturation dropped as low as 49%, and ventilation became increasingly difficult. The patient s disease severity rapidly progressed to ARDS (Fig. 1). He could not be ventilated in the volume control mode and required bagvalvetube ventilation at high pressure to achieve peripheral oxygen saturation in the range of 50% to 60%. Red frothy fluid flowed via the endotracheal tube. Further deterioration in oxygenation (PaO 2 /FiO 2 =29.8) with hemodynamic instability was observed. Despite maximal aggressive ventilator settings at a peak inspiratory pressure of 30 cmh 2 O, a positive endexpiratory pressure (PEEP) of 10 cmh 2 O, a respiratory rate of 40/min, and a fraction of inspired oxygen of 1.0, analysis of arterial blood gases showed a ph of 7.300, a PaCO 2 of 44.0 mmhg, a PaO 2 of 29.8 mmhg, an HCO 3 of 21.2 mmol/l, and oxygen saturation of 49% (Table 1). Highfrequency positivepressure ventilation was used in vain. As respiratory failure occurred and worsened, despite maximal conventional supportive therapy, the decision was made to commence ECMO, 3 days after the completion of surgery. The basic setup of the venovenous ECMO circuit is shown in Fig. 2. Venous blood is passively drained from the inferior vena cava through a 17 Fr heparinbonded cannula introduced percutaneously via the femoral vein. A backflow heparinbonded cannula (15 Fr) is introduced 334

3 ChihHsien Lee, et al. Table 1 Gas, oxygenation and ventilator setting, and clinical course On ECMO Off ECMO Repair lift kidney Pulmonary function deterioated ARDS Poor oxygenation Improve oxygenation Day 0 Day 2 Day 3, morning Day 3, evening Day 4 Day 7 Day 8 Before After Before ECMO ECMO Day 1 ECMO Day 4 off ECMO Mode Face tent SIMV VC VC PC SIMV Respiratory rate Peak inspiratory pressure Pressure 24 PEEP ph PaCO PaO HCO SaO FiO 2 (ventilator) 60% % 40% 30% FiO 2 (ECMO) ACT PT 12.2/ / /11.5 PTT 24.9/29.7 >180/ /30.2 INR B/R WBC HgB PLT N/L 85.7/ / / / /11.0 percutaneously into the superior vena cava via the internal jugular vein. All materials of the extracorporeal circuit are heparincoated. Extracorporeal blood flow, which determines the amount of artificially supplied oxygen, is initially set to L/min. Gas flow, which determines the amount of CO 2 removed, is adjusted to 210 L/min. A ph of 7.2 is used as the lower limit in patients with residual renal function. Patients are weaned off ECMO when extracorporeal gas flow is 2 L/min and at least 80% of total oxygen delivery is supplied by the patient s own lungs. Systemic anticoagulation is necessary, but can cause bleeding into injury sites, leading to fatal outcomes. The target activated clotting time (ACT) is s. We check ACT every 2 h. Lung expansion is maintained with as little ventilator support as possible. Immediately after the initiation of ECMO in this child, 335

4 ECMO for traumatic ARDS in a child Fig. 3 Chest Xray showed improvement of the lung parenchyma after 5 days of ECMO perfusion. arterial oxygen saturation increased from 94% to 98%, and the hemodynamic parameters returned to normal values. The ventilator setting was adjusted to normal with a mean airway pressure of 21 cmh 2 O, a PEEP level of 6 cmh 2 O, and an FiO 2 of 0.. In the ICU, the patient remained hemodynamically stable on ECMO, mechanical ventilation, and a dopamine drip at 3μg/kg per min. After 5 days of ECMO, the patient s chest radiography had improved dramatically (Fig. 3) and his oxygen requirement had been reduced to 40%. He was then successfully weaned off ECMO on postoperative day 8, with no change in his mixed venous saturation and a stable cardiac index. The cannulas were removed at the bedside without problems. The patient was returned to conventional ventilatory support. The patient was extubated on postoperative day 11. Acute pancreatitis was noted on postoperative day 13, and he then received conservative treatment. The patient was finally discharged from ICU 30 days later. He was discharged in excellent condition on postoperative day 42. He has been doing very well during the past 10 months of followup. DISCUSSION Hill and colleagues 8 successfully applied ECMO to a trauma patient suffering acute posttraumatic pulmonary insufficiency 6 days after the repair of a transected aorta. Machiels and colleagues 9 successfully applied venovenous ECMO in lifethreatening radiocontrastmediated ARDS. ECMO has been shown to be an effective treatment for neonatal respiratory failure 10. Initially, the concept of keeping the lungs at rest to facilitate lung healing triggered considerable enthusiasm among clinicians treating patients with severe ARDS 2. ECMO realizes a convincing therapeutic concept. ECMO is a therapy that was adapted from intraoperative cardiopulmonary bypass. The technique of venoarterial perfusion was a major shortcoming of ECMO because it had the potential to cause additional ischemic lung injury. Kolobow s group eliminated this problem by developing the venovenous perfusion technique 2. A venovenous approach is most frequently used to preserve lung perfusion. We are certain that our patient would not have survived without treatment with ECMO. ECMO provides full respiratory support and hemodynamic support when needed, allows the native lung to heal without being forced to meet the body s metabolic demands, and avoids the morbidity that results from prolonged ventilation with highpeak inspiratory pressures and fractions of inspired oxygen 1. Even though the ECMO circuit provided all necessary gas exchange, the endotracheal tube and mechanical ventilation were retained to provide a route for pulmonary toilet and airway access in case of circuit malfunction or emergency. A large body of literature supports ventilating the lungs with limited oxygen concentrations, small tidal volumes, minimal peak inspiratory pressure, high frequency, and sufficient PEEP to approximate normal functional residual capacity 3,4. We decided to use venovenous ECMO and not venoarterial ECMO for several reasons. This was a young patient with good underlying cardiac function. Venoarterial ECMO is more invasive than venovenous ECMO and requires cannulation of either the femoral or carotid arteries. Myocardial oxygenation is actually better with venovenous ECMO than with venoarterial ECMO 11. Venovenous ECMO also avoids ischemic injury to the limbs. We have previously used highflow venovenous perfusion to support respiration in total pulmonary failure 12. Fast entry is defined as PaO 2 /FiO 2 50 mmhg at a PEEP of at least 10 cmh 2 O (US study: 5 cmh 2 O) for 2 h 2. Some patients cannot sustain a treatment trial of 2 h 2,4. They must be crashed on ECMO because of severe lifethreatening hypoxemia (PaO 2 40 mmhg) 2. This is referred to as immediate entry 2,4. The incidence of complications associated with the extracorporeal circuit is low, and include bleeding from puncture sites or operative wounds and massive dissolved inorganic carbon (DIC), rupture of the tubing system, 336

5 ChihHsien Lee, et al. plasma leakage of the oxygenators, vascular injury, infection, and sepsis 1,3,8,1315. The main risk of ECMO in all patients, and especially in trauma patients, is bleeding secondary to systemic anticoagulation 3. Systemic anticoagulation is necessary, but can cause bleeding into injury sites, leading to fatal outcomes. The major method for successfully controlling bleeding tendency is the use of a heparincoated circuit. In treating our patient, all materials of the extracorporeal circuit were heparincoated, decreasing the need for systemic anticoagulation. The target ACT was s to decrease bleeding risk. ECMO was performed with a centrifugal type pump to decrease the destruction of blood cells. This case demonstrates that ECMO can be used safely at the bedside in an ICU, avoiding dangerous transport to the operating room. Peripheral femoral cannulation was used in our patient, which proved to be a valuable alternative to the more invasive central approach. ECMO is not a magic bullet for the treatment of ARDS. Therefore, it seems advisable to keep ECMO in our therapeutic armory for the treatment of severe ARDS. ECMO is usually considered the last therapeutic resort for severe ARDS, and is likely to increase survival after all other options have failed. REFERENCES 1. Hilt T, Graves DF, Chernin JM, Angel CA. Pediatrics: successful use of extracorporeal membrane oxygenation to treat severe respiratory failure in a pediatric patient with a scald injury. Crit Care Nurse 1998;18: Georg M, Torsten L, Klaus G, Edward F, Albert B. Extracorporeal membrane oxygenation: a tenyear experience. Am J Surg 2000;182: Sasadeusz KJ, Long WB, Kemalyan N, Datena SJ, Hill JG. Successful treatment of a patient with multiple injuries using extracorporeal membrane oxygenation and inhaled nitric oxide. J Trauma 2000;49: Paulson TE, Spear RM, Peterson BM. New concepts in the treatment of children with acute respiratory distress syndrome. J Pediatr 1995;127: Filston HC. What s new in pediatric surgery. Pediatrics 1995;96: Kocis KC. Pediatric cardiac extracorporeal membrane oxygenation: supporting life or prolonging death? Crit Care Med 2000;28: Perchinsky MJ, Long WB, Hill JG, Parsons JA, Bennett JB. Extracorporeal cardiopulmonary life support with heparinbonded circuity in the resuscitation of massively injured trauma patients. Am J Surg 1995;169: Hill JD, O brien TG, Murray JJ, Dontigny L, Bramson ML, Osbron JJ, Gerbode F. Prolonged extracorporeal oxygenation for acute posttraumatic respiratory failure (shocklung syndrome). N Engl J Med 1972;286: Machiels JP, Evrard P, Dive A, Bulpa P, Installe E. Venovenous ECMO in lifethreatening radiocontrast mediatedards. Intensive Care Med 199;9: Vlasselaers D, Verleden GM, Meyns B, Van RD, Demedts M, Lerut A, Lauwers P. Femoral venoarterial extracorporeal membrane oxygenation for severe reimplantation response after lung transplantation. Chest 2000;118: Schupp M, Swanevelder CJ, Peek GJ, Sosnowski AW, Spyt TJ. Postoperative extracorporeal membrane oxygenation for severe intraoperative SIRS 10 h after multiple trauma. Br J Anaesth 2003;90: Zapol WM. A Nordic ECMO saga or whither ECMO? Intensive care med 1991;17: Montgomery VL, Strotman JM, Ross MP. Impact of multiple organ system dysfunction and nosocomial infections on survival of children treated with extracorporeal membrane oxygenation after heat surgery. Crit Care Med 2000;28: Werns SW. Percutaneous extracorporeal life support: reserve for patients with reversible causes of shock and cardiac arrest. Crit Care Med 2003;31: Wetterberg T, Steen S. Total extracorporeal lung assista new clinical approach. Intensive care med 1991; 17: