LUNG AND AORTIC INJURIES
| SURGICAL OPTIONS IN THE MANAGEMENT OF LUNG INJURIES —Robert C. Mackersie, MD, Professor, Department
of Surgery, University of California, San Francisco, School of Medicine, and Director, Trauma Service, San Francisco
General Hospital
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| Background: most operative lung injuries not blunt; occasionally, blunt injury becomes penetrating; 20% to 40% of penetrating
lung injuries require resection; general indications for related thoracotomy—majority (94%-96%) of all thoracic
trauma will not require thoracotomy to control hemorrhage or other problems; hemorrhage >1500 mL; persistent or
recurrent shock (attributable to thoracic injury); persistent chest tube output; refractory (massive) hemothorax; massive
endobronchial bleeding; major air embolism—results from communication between bronchi and pulmonary vessels; air
and blood do not mix; air in pulmonary vein causes cardiac arrest and embolism; endobronchial bleeding, in and of itself,
harmful; air trapped in lung parenchyma and exits via pulmonary vein; can cause coronary and cerebral embolism and
airlock in left ventricle, leading to instant death; relatively uncommon; endobronchial bleeding—more common; blood
trapped in lung; exits via adjacent bronchus; alveolar flooding damaging to lung parenchyma; albumin component in
whole blood strong inhibitor of surfactant producing alveolar collapse; albumin also chemoattractant and precursor to
acute respiratory distress syndrome (ARDS); important to perform serial x-rays to assess which patients may benefit
from early operation
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| Initial steps: tracheal intubation—usually no time for double-lumen tubes (in general, not worth doing); if massive endobranchial
hemorrhage present, particularly on left side, perform directed right mainstem intubation; bronchial blockers
one of less complicated interventions; delaying thoracotomy to control hemorrhage often mistake; thoracotomy—
resuscitative; unless patients present in near-arrest, they should be transported to operating room (OR) for optimal conditions;
positioning—keep options open; most patients have combined thoracoabdominal injuries; anterolateral thoracotomy
and laparotomy if necessary; beware of “down lung syndrome” (use of single-lumen tubes, full posterolateral
thoracotomy with patient up, and if excessive endobronchial hemorrhage present, bleeding can drop down into “good”
lung; this causes injury to unaffected lung, which produces severe intraoperative hypoxia and postoperative problems);
prevented if hilar control of hemorrhage initiated as soon as possible; full posterolateral thoracotomy acceptable if injuries
clearly isolated; anterolateral thoracotomy has advantage of allowing entrance into abdomen if necessary; identify
bleeding site—necessary once in chest (not always lung); look for tamponade first (easiest to treat); major vascular injuries
potential bleeding source; hilar control—done manually or through hilar “twist” (requires cutting inferior pulmonary
ligament); clamps dangerous in this area
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| Surgical options: simple oversew—do not oversew deep tracts (causes trapping of air and blood in contained space);
stapled or sutured tractotomy and oversew (more commonly used treatment for more serious lung injuries); nonanatomic
wedge resection; lobectomy and pneumonectomy reserved for unique cases; less resection and greater preservation of
lung parenchyma better for patient; use with caution to avoid trapping of air and blood; incorporate entire suture line;
most bleeding self-limited; newer tissue adhesives and glues used; wedge resection—feasible in periphery of lungs; reinforce
suture line carefully; avoid lung sequestrum (nonperfused or nonventilated portion of lung that collapses);
tractotomy—most commonly performed procedure for major and more central lung injuries (gunshot wound classic
model); prevent mixing of blood and air to gain control of hemorrhage and bronchial leak (necessary to open tract); easiest
way to open tract to use gastrointestinal anastomosis (GIA) staplers and open up thinnest portion of lung possible,
paying attention to anatomy; be sensitive to parenchymal thickness; good hilar control allows time to control bleeding
and air-blood interface; simple oversew augmented with tissue adhesives (eg, fibrin glue, glutaraldehyde compounds) to
close lung and reattach pleural visceral attachment; some patients develop ARDS-type syndrome, with relatively high
peak airway pressures; this can wreak havoc on tenuous stapled suture line with large bronchopleural fistulas (forestalled
by oversewing stapled suture lines with running suture); avoid lung sequestrum; anatomic resections—lobectomies and
pneumonectomies; reserved for more destructive injuries; avoid if possible; data suggest outcomes equivalent with anatomic
or nonanatomic pulmonary resections; may be necessary to perform intrapericardial proximal vascular control
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| Factors related to outcome: age; associated injuries; shock; transfusion requirements; associated comorbidities; degree
of endobronchial hemorrhage; nonventilated lung or nonperfused lung (sequestrum) created sometimes by surgical tractotomy
(can develop infection); with infection, reoperation problematic
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| Postpneumonectomy problems: massive transfusion and blood; increased sensitivity to pulmonary edema; endobronchial
bleeding; right heart failure; ventilator-induced lung injury (worse with one lung); several studies show dismal outcome;
National Trauma Database Study showed that independent of factors (eg, shock, massive transfusion,
comorbidities), simply removing lung detrimental to patient and independent predictor of mortality; sparing parenchymal
resection (to extent possible) helps with outcome
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| AORTIC DISSECTION —John M. Marek, MD, Associate Professor, Division of Vascular Surgery, Department of Surgery,
University of New Mexico Health Sciences Center, Albuquerque
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| Incidence: most frequent catastrophic aortic disorder; estimated 2 to 3 times more frequent than ruptured abdominal aortic
aneurysms; medical management of type B dissections associated with 30-day mortality of ≈12%; most deaths with
type A or B dissections due to rupture of aorta; most patients >40 yr of age at presentation; in older population, estimated
incidence 5-times greater in men than women (equal in younger population); 50% of dissections in younger women occur
during pregnancy (usually during third trimester or labor), possibly associated with preeclampsia or hypertension; higher
incidence in patients with connective tissue disorders (eg, Marfan’s syndrome); also in bicuspid aortic valve and aortic
coarctation; cocaine use, especially in younger patients; iatrogenic procedures (eg, cardiac catheterization)
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| Natural history: estimated 10% to 15% of patients die suddenly in first 15 min in type A dissection; with no intervention,
estimated mortality rate, 1% to 2%/hr; 50% of patients alive at 48 hr; 10% survival rate at 3 mo; without intervention,
type A dissections have 1-mo survival rate, with emergency surgery gold standard; in type B, with medical
management, 70% survival at 1 mo not unusual; type I basically type A dissection; type II mostly type B dissection; even
with operative interventions, not actually curing patients of dissection
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| Classifications: Stanford—type A, any involvement of ascending aorta (biggest prognostic indicator for acute management
of patients); DeBakey—types I, II, IIIa, and IIIb; type I involves ascending aorta down to iliac bifurcation; type II
involves only ascending aorta; type IIIa involves descending aorta to inguinal ligament; in type IIIb, involvement all way
down to distal aorta; most occur in ascending aorta (proximal two-thirds or type A dissection); only 20% type B dissections;
in aortic arch (neither classic type A nor type B), 10%; abdominal dissections fairly infrequent; initial entry point
occurs within first 9 cm from aortic valve (takeoff of left subclavian artery) in most dissections
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| Pathogenesis: complex; inciting event rupture of intima, whereby blood gets into subintimal plane, and dissection occurs
in medial layers; one postulated explanation that degeneration of medial fibers decreases cohesiveness of aortic layers;
previously, term cystic medial necrosis used to describe pathologic entity of aortic dissection; medial degeneration more
extensive as patients get older, and with higher incidence of hypertension, connective tissue disorders, and bicuspid aortic
valve
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| Clinical presentation: acute (<2-wk duration) or chronic; patients with type A dissection typically younger, with less
hypertensive history; in type B dissections, 70% to 80% of patients have hypertension (less frequent in type A); higher incidence
of congenital defects in type A dissections; initial presentation varied; ranges from hypovolemic shock due to
rupture, to cardiogenic shock from tamponade; aortic regurgitation common in type A dissection; most patients initially
present with hypertension; International Registry of Acute Aortic Dissection (IRAD) involves 11 countries and 22 centers
of excellence in aortic dissection management; pain—sudden onset classic presentation (highly associated with aortic
rupture); usually sharp; classic ripping or tearing pain in ≈51% of patients; mostly in chest; whether pain in anterior
chest or back related to location of dissection; in type A dissections, anterior chest pain typical; in aortic arch dissections,
anterior chest or back pain typical; in dissections that extend to descending aorta or type B dissections, interscapular pain
or abdominal pain seen; abdominal pain present in 30% of patients (possibly due to dissection extending distally); index
of suspicion varies with type of pain at presentation; most physicians suspect aortic dissection with chest and back pain
(less suspected if presentation typical anterior chest pain); only 8% of physicians suspect aortic dissection if presentation
abdominal pain; pain lasts from hours to days initially; if pain lasts longer, or if pain-free interval present with return of
chest pain, may indicate progression of dissection or impending rupture (ominous sign); 25% of patients present with hypovolemic
or cardiogenic shock; pulse differential—relatively common; in upper extremities, normal right arm pulse
with diminished left arm pulse associated with propagation of dissection and occlusion of left subclavian artery; in lower
extremity, present in 15% to 20% of patients presenting with acute lower extremity ischemia; if renal arteries involved
with branched vessel occlusion, patient may have oliguria or anuria; cardiac murmur in 25% of patients (due to aortic regurgitation
frequently seen in proximal type A dissections); 20% to 30% present with stroke, paraplegia, syncope, or
Horner syndrome; aortic regurgitation frequently present in type A dissections and second most common cause of death
(most common cause aortic rupture); cardiac tamponade or acute pericardial effusion ominous sign that patient needs
emergency surgery after diagnosis (or diagnosis made in OR with transesophageal echocardiography); low coronary perfusion
with type A dissection not infrequent because of involvement of cusp of coronary arteries; >8% of emergency department
(ED) visits for chest pain; majority due to myocardial infarctions (MIs); missed diagnosis of aortic dissection
(ie, confusing with MI) potentially catastrophic, especially if patient given thrombolytics or if delay in diagnosis of type
A dissection; initial suspicion of aortic dissection usually not good in these patients (as low as 15% suspected by physicians);
20% of diagnoses made at autopsy
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| Diagnostic tests: electrocardiography—frequently abnormal; ST changes not infrequent but nonspecific; usually initial
screening test; chest x-ray—initial screening test for patient with chest pain; usual tests include computed tomography
(CT), magnetic resonance imaging (MRI), echocardiography, and rarely, angiography (formerly gold standard; presently
used for intervention, not for diagnosis); MRI—gold standard for diagnosis; 100% sensitivity and specificity; good at locating
proximal ascending aortic dissection and extent of dissection; problem of availability in ED; cannot be performed in patients
with metallic implants; CT angiography—most frequently utilized study for diagnosis; not as sensitive or specific,
due to difficulty in visualizing ascending aorta; requires intravenous (IV) contrast load; retrograde dissection into aortic
arch—worst prognosis; most patients require intervention, due to higher mortality within first year; treated with endoluminal
graft; transesophageal echocardiography—more accurate than transthoracic echocardiography; safe; quick; performed
at bedside or in ED; sensitive; able to quantify aortic regurgitation, pericardial effusion, and left ventricular
dysfunction; investigator-dependent (limitation); in some centers, used during endoluminal graft placement to ensure occlusion
of false lumen; less effective for evaluating aortic arch (trachea blocks view); angiography—invasive and time-consuming
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| Medical management: IV β-blockers; unless patient hypotensive, key in initial medical management; if not effective, start
nitroprusside; starting with nitroprusside before β-blocker propagates dissection; labetalol good alternative; lifelong β-blocker
therapy necessary, regardless of other procedures peformed; if dissection has uncomplicated course, transition to oral therapy
possible
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| Indications for surgery: include all type A dissections, unless prohibitive operative risks present; in type B dissections,
classic indications include rupture, large left pleural hemothorax, visceral ischemia, continued pain, and uncontrolled
hypertension (impending rupture); operative mortality high; if patient stable with no malperfusion syndrome,
mortality rates close to 10% to 12% (higher if patient in shock or with malperfusion syndrome); patients impaired with
bypass, circulatory arrest, and retrograde cerebral perfusion; aortic valve replacement if necessary; for type B dissections,
classic open surgery also carries high mortality rates (14%-16% in perioperative period); of great concern in open surgery
and endografting, depending on how much of thoracic aorta replaced or covered, incidence of paraplegia (permanent in
20%-30%); branched vessel involvement in >40% (no intervention necessary if in subclavian artery; necessary in carotid,
visceral, and renal arteries); number of patients present with acute lower extremity ischemia, more commonly on left
side, due to nature of how dissection propagates; for endoluminal approaches to branched vessel occlusions, determine
whether significant compression of true lumen present (treat first)
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| Endoluminal grafts: Gore TAG device approved by Food and Drug Administration (FDA) in March 2005 for descending
thoracoabdominal aneurysms; intravascular ultrasonography while performing procedures critical because necessary to be
in true lumen throughout course of procedure; complications from endoluminal grafts mostly related to access; for chronic
type B dissections, most patients survive initial hospital stay with medical management; however, some patients continue to
expand aorta and at risk for rupture; according to data, 1-yr survivability after type B dissection, 50% to 90%; close follow-
up mandatory; aorta dilated to 5.5 to 6.5 cm threshold for action to prevent rupture; most patients die of rupture in follow-up;
20% to 40% of patients eventually develop aneurysmal degeneration requiring surgery; ≈25% of thoracoabdominal aneurysms
due to chronic dissections; if not treated within 1 yr, most patients die from rupture; at 5 yr, only 20% alive; patency
of false lumen—thought that patients whose false lumen thrombosed initially have better outcome; patent false lumen predictor
of dissection-related death; if initial diameter of aorta during hospitalization >45 mm with patent false lumen, at 1, 5,
and 10 yr, most patients have dilation of aorta; if diameter smaller initially, with occluded false lumen, most patients have
fairly benign course; study—looked at false lumen patency; those with partial thrombosis of false lumen had worst outcome
at 1 yr; theory that mean arterial pressures in partially thrombosed false lumen higher; INvestigation of STEnt grafts
in patients with type B Aortic Dissection (INSTEAD) trial—not yet published; 136 participants with uncomplicated
type B dissections; no deaths in medical management arm; 11% required stent grafts due to significant dilation of aorta; 10%
incidence of deaths at 1 yr in stent graft arm; early intervention with stent grafting may be unwarranted for patients with uncomplicated
type B dissection (just close follow-up)
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Suggested Reading
Estrera AL et al: Update on outcomes of acute type B aortic dissection. Ann Thorac Surg 83:S842, 2007; Gómez-
Caro A et al: Role of conservative medical management of tracheobronchial injuries. J Trauma 61:1426, 2006;
Hansen MS et al: Frequency of and inappropriate treatment of misdiagnosis of acute aortic dissection. Am J Cardiol
99:852, 2007; Hatzaras IS et al: Role of exertion or emotion as inciting events for acute aortic dissection. Am J Cardiol
100:1470, 2007; Huh J et al: Surgical management of traumatic pulmonary injury. Am J Surg 186:620, 2003; Karmy-
Jones R et al: Descending thoracic aortic dissections. Surg Clin North Am 87:1047, 2007; Kawanishi Y et al: Three
cases of newly developed paraplegia after repairing type A acute aortic dissection. Ann Thorac Surg 84:1738, 2007;
Khaladj N et al: Should a patient with acute aortic dissection type A go to the intensive care unit or operating room?
Ann Thorac Surg 84:1069; author reply 1069, 2007; Lee CH et al: Type A aortic dissection: a hidden and lethal cause
for failed thrombolytic treatment in acute myocardial infarction. Heart 93:825, 2007; Odero A et al: Endovascular treatment
of acute type B dissection and Kommerell's diverticulum. Ann Thorac Surg 84:1736, 2007; Pape LA et al: Aortic
diameter >or = 5.5 cm is not a good predictor of type A aortic dissection: observations from the International Registry of
Acute Aortic Dissection (IRAD). Circulation 116:1120, 2007; Schoder M et al: Endovascular repair of acute type B
aortic dissection: long-term follow-up of true and false lumen diameter changes. Ann Thorac Surg 83:1059, 2007; Sorokin
VA et al: Combined open and endovascular repair of acute type A aortic dissection. Ann Thorac Surg 83:666,
2007; Tarver K et al: Extensive aortic dissection presenting as acute inferior myocardial infarction. Heart 93:1225,
2007; Tsai TT et al: Partial thrombosis of the false lumen in patients with acute type B aortic dissection. N Engl J Med
357:349, 2007; Wong B: Partial thrombosis of the false lumen in aortic dissection. N Engl J Med 357:1868; author reply
1868, 2007.
Educational Objectives
| The goal of this program is to improve the surgical management of lung injuries and aortic dissection. After hearing
and assimilating this program, the clinician will be better able to:
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 | 1. Recognize the indications for thoracotomy due to lung injuries.
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| 2. Differentiate, and determine the most appropriate, surgical options for lung injuries.
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| 3. Review the Stanford and DeBakey classifications of aortic dissection.
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| 4. Distinguish between type A and type B aortic dissections, based on pain characteristics.
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| 5. Review the indications for surgery in aortic dissection.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the
planning committee to disclose relevant financial relationships within the past 12 months that might create any personal
conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes
quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning
committee reported nothing to disclose.
Acknowledgements
Dr. Mackersie was recorded at the Detroit Trauma Symposium, held November 8-9, 2007, in Detroit, MI, and sponsored
by the DMC Detroit Receiving Hospital and Wayne State University School of Medicine. Dr. Marek was recorded
at Current Concepts in General Surgery and Trauma Update, held September 5-7, 2007, in Albuquerque,
NM, and sponsored by the University of New Mexico Health Sciences Center, Department of Surgery, and Office of
Continuing Medical Education. The Audio-Digest Foundation thanks Drs. Mackersie and Marek and the sponsors for
their cooperation in the production of this program.
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