john j. gallagher , rn, msn, ccns, ccrn, rrt - aacn · pdf filejohn j. gallagher , rn, msn,...

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AACN Advanced Critical Care Volume 25 , Number 4 , pp 375 - 386

© 2014 AACN

DOI: 10.1097/NCI.0000000000000059

Management of Blunt Pulmonary Injury John J. Gallagher , RN, MSN, CCNS, CCRN, RRT

John J. Gallagher is Clinical Nurse Specialist/Trauma Program Manager, Hospital of the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19104 ( [email protected] ).

The author declares no conflicts of interest.

Introduction Chest trauma accounts for 25% of all civilian deaths due to trauma, second only to severe head injury. 1 The thoracic cavity contains mul-tiple organ systems that may be injured, including the pulmonary, cardiovascular, digestive, and musculoskeletal systems. Rapid and systematic evaluation of the patient to identify and manage these injuries is essential to reduce associated death and disability. Inju-ries of the pulmonary system must be identi-fied in the initial assessment, because they can be immediately life-threatening. 1–5 Similar to other traumatic injuries, chest trauma results from both blunt and penetrating mechanisms of injury. Penetrating injuries include stab or gunshot wounds as well as impalement. Blunt injuries result from falls, motor vehicle or motorcycle crashes, pedestrian/vehicle colli-sions, explosions, and other blunt force mech-anisms. 3–5 Blunt chest injuries may be more challenging to identify, as external evidence of injury may not indicate the degree of underly-ing organ injury. 1 , 4 , 5 Blunt pulmonary injuries

are a prime example of this complexity. The identification and management of these inju-ries are the focus of this article.

Scope of Injury Blunt pulmonary injuries are caused by a trans-fer of force to the thoracic cavity that injures underlying structures. The bony thorax (ribs and sternum), pleural space, intrathoracic airways, and the lung parenchyma may be injured. These injuries may occur singularly or in combination, depending on the underlying mechanism. 1 , 3–5 For the purpose of this discus-sion, the focus is primarily on blunt injuries that involve the pleural space, airways, and lung.

ABSTRACT Thoracic injuries account for 25% of all civil-ian deaths. Blunt force injuries are a subset of thoracic injuries and include injuries of the tracheobronchial tree, pleural space, and lung parenchyma. Early identification of these injuries during initial assessment and resuscitation is essential to reduce associ-ated morbidity and mortality rates. Manage-ment of airway injuries includes definitive airway control with identification and repair of tracheobronchial injuries. Management of pneumothorax and hemothorax includes pleural space drainage and control of ongo-ing hemorrhage, along with monitoring for

complications such as empyema and chylo-thorax. Injuries of the lung parenchyma, such as pulmonary contusion, may require sup-port of oxygenation and ventilation through both conventional and nonconventional mechanical ventilation strategies. General strategies to improve pulmonary function and gas exchange include balanced fluid resuscitation to targeted volume-based resuscitation end points, positioning ther-apy, and pain management. Keywords: chest trauma , hemothorax , pneu-mothorax , pulmonary contusion , tracheo-bronchial injury

Copyright © 2014 American Association of Critical-Care Nurses. Unauthorized reproduction of this article is prohibited.

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Injuries Involving the Pleural Space

Pneumothorax Blunt force injuries of the chest may result in collection of air (pneumothorax), blood (hemo-thorax), or a combination of the 2 within the pleural space. Pneumothorax occurs primarily when the lung is lacerated by the ribs or when the lung is compressed, which causes a disrup-tion of the lung’s integrity and allows air to col-lect between the parietal and visceral pleura. In some cases, the pneumothorax may be rela-tively small, and evaluation with serial chest radiographs (CXRs) may be preferable to place-ment of a chest tube. 3 , 6 , 7 Patients may complain of chest pain as a result of air in the pleural space and associated rib fractures. Diminished breath sounds and subcutaneous emphysema may be noticeable, but respiratory distress may not be present. These patients are usually moni-tored for worsening respiratory distress, along with having serial CXRs, to detect expansion of the pneumothorax and potential need for chest tube placement. For patients who require posi-tive pressure ventilation (PPV) and/or general anesthesia, the decision may be made to insert a chest tube, as a pneumothorax can expand under PPV, resulting in a tension pneumotho-rax. However, more recent data support obser-vation of stable patients with pneumothorax who require PPV. 3 , 6 , 8

In some cases, pneumothorax may not be present on the initial CXR before or immedi-ately after intubation. After a period of PPV, a pneumothorax may be detected on repeat films or during computed tomography (CT) of the chest. Such an occult pneumothorax occurs in approximately 5% to 15% of patients with blunt injury. 7 , 9–14 Of those with an occult pneu-mothorax, approximately 10% require chest tube placement. 8 Ongoing evaluation for devel-opment of physiological changes indicating a tension pneumothorax is essential. Reduction in oxygen saturation, increases in peak inspira-tory pressure, and unexplained hypotension should prompt suspicion of tension pneumo-thorax.

Tension Pneumothorax Tension pneumothorax can occur as air rapidly collects in the pleural space around the injured lung. The increasing pressure compresses the mediastinal structures, shifting them to the side opposite the injury, ultimately compressing the

uninjured lung. Clinically, the patient may exhibit decreased or absent breath sounds on the injured side and palpable subcutaneous emphysema across the chest, with a tracheal shift from midline to the uninjured side as a late finding. High peak inspiratory pressures may develop in patients undergoing mechani-cal ventilation, triggering ventilator alarms for high pressure and low tidal volume/minute ventilation. Compression of the heart and great vessels reduces cardiac preload and increases afterload, causing obstructive shock. Back pressure on the venous system results in jugular vein distention if adequate blood volume is pre-sent in the intravascular space. Tachycardia and hypotension deteriorating into cardiac arrest may be manifested as pulseless electrical activity. If an arterial catheter is present, the waveform may become dampened or flat. 2 , 3 , 8

Treatment of Tension Pneumothorax Tension pneumothorax is rapidly fatal and requires immediate intervention. Rapid needle decompression with a large 16- or 14-gauge, 2.25-inch (5.7-cm) peripheral venous catheter inserted into the second or third rib intercostal space at the midclavicular line should be per-formed immediately to relieve the tension pneumothorax. This needle decompression should be followed by insertion of a chest tube. In patients who arrive in cardiac arrest after blunt traumatic injury, bilateral needle decom-pression followed by bilateral placement of chest tubes may be undertaken as part of the initial assessment and interventions. 2 , 3

Chest tube size depends on the size of the patient and on the condition being treated. In trauma resuscitation, larger tubes such as 32F or 36F are often placed on the basis of findings on initial physical examination rather than CXR. 2 , 3 , 8 Because the underlying condition may be either pneumothorax or hemothorax, a larger tube will facilitate rapid drainage of blood with less potential for tube occlusion. Decisions to place smaller chest tubes may be made depending on radiological findings and the patient’s condition. In trauma patients, the chest tube is usually placed at the fourth or fifth rib intercostal space between the anterior and midaxillary line. 2

In most cases, a chest tube inserted and connected to a negative-pressure chest drainage unit will result in reexpansion of the lung. Intermittent bubbling in the water seal chamber



VOLUME 25 • NUMBER 4 • OCTOBER–DECEMBER 2014 BLUNT PULMONARY INJURY

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of the chest drain should be expected with PPV breaths or the patient’s spontaneous breathing. Continuous bubbling in the water seal chamber not associated with drainage system leaks, loss of dressing integrity, or chest tube dislodgment should prompt suspicion of an unresolved lung defect such as a bronchopleural fistula or bron-chial injury. A decision may be made to place a second chest tube to assist in further lung expansion and to perform a bronchoscopy to identify potential bronchial injuries. 3 , 7 , 8 , 15

Hemothorax In blunt chest injury, hemothoraces may result from intercostal vessel injury and lung lacera-tion associated with rib fractures or from injury of the great vessels in the chest. 3 , 8 , 16 In many cases, bleeding associated with injury of the intercostal artery or vein is limited. Reex-pansion of the lung and evacuation of the hemothorax reduce further bleeding from the low-pressure intercostal vessels. The volume of blood after initial insertion of the chest tube and the presence of ongoing bleeding dictate the need for thoracotomy to identify and stop hemorrhage. A massive hemothorax is defined as 1500 mL or more initially from the chest or the presence of 200 mL of blood per hour for 4 hours. 3 , 8 , 15 The underlying cause of massive hemothorax may be laceration of the lung, pulmonary artery or vein, or aorta.

Although hemothorax may be identified by initial drainage of blood from the chest tube, a CXR also may be helpful. Initial CXR in the trauma resuscitation room is often taken as an anterior to posterior view with the patient supine. Findings consistent with hemothorax on an anteroposterior CXR include haziness of the lung fields on the affected side. Up to 1000 mL of blood may be present in the pleural space in such cases, and the amount may be difficult to quantify with the patient in this position. 3 , 16 An upright CXR is ideal for diag-nosis of hemothorax. If the patient is in the semi-Fowler position, fluid may appear at the base of the affected hemithorax, blunting the costophrenic angle. The presence of 200 mL of blood or more may produce this result. CXR findings associated with hemothorax that may indicate aortic injury include blood collected in the left apical pleural space (apical cap) and large hemothoraces on the left side. Increas-ingly, focused assessment with sonography for trauma (FAST) is being used to diagnose pneu-mothorax and hemothorax before CXR.

Pneumothorax may be identified by “nonslid-ing” between the visceral and parietal pleura with breathing/ventilation on the affected side. Hemothorax may appear as an anechoic region (appearing black or without echo reverbera-tion) just above the diaphragm. 3 , 16 Similar to its use in the diagnosis of other traumatic injuries/conditions, the accuracy of focused assessment with sonography for trauma is highly operator dependent.

Treatment of Hemothorax Management of hemothorax includes insertion of a large chest tube as described earlier to evacuate blood from the pleural space and reexpand the lung. 2 , 3 , 8 , 16 Through the use of an autotransfusion chest drain system ( Figure 1 ), the collected blood may be given back to the patient, possibly reducing the need for transfu-sion of allogeneic blood products. Limitations of this process include patients who require ongoing massive transfusion, suspected con-tamination of the collected blood, known met-astatic disease, and extended duration of time from collection to transfusion. 17 , 18

Ongoing care of the patient with pneumo-thorax or hemothorax includes monitoring for changes in respiratory condition and onset of distress. Monitoring the chest drainage system for patency is essential, as clots may form in the thoracostomy tube or drainage system. 3 , 16 In addition to creating conditions that may result in tension pneumothorax or hemotho-rax, retained blood in the pleural space can clot and form an empyema. Removal of these collections may require the use of radiologic or video-assisted thoracoscopic drainage or thor-acotomy. 7 , 19 , 20 Ongoing drainage of blood and serous fluid may be expected for several days, especially with changes in the patient’s posi-tion that facilitate drainage of retained blood from the pleural space. If bloody output increases, or hourly output is consistently 200 mL or greater, the surgical team should be notified, as the patient may require a thoracot-omy for surgical management of bleeding. 3 , 7 , 16

Thoracic Duct Injury Blunt injury of the thoracic duct is rare and often associated with blunt injuries of the chest or neck. In blunt trauma, the duct may rupture just above the diaphragm during hyperexten-sion injuries of the thoracic spine. 21–23 Clinically, this condition may be diagnosed by chylous drainage from a chest tube. The classic




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description of “milky white” drainage may be absent if the chyle is mixed with blood or pleu-ral fluid and may be more noticeable as bloody drainage subsides. If suspected, drainage may be sent to the laboratory to identify the pres-ence of triglycerides. Triglyceride levels greater than 110 mg/dL (to convert to millimoles per liter, multiply by 0.0113) may be diagnostic, whereas levels between 50 and 110 mg/dL may require further lipoprotein analysis. In addi-tion to thoracic drainage, treatment includes low-fat diet, parenteral nutrition, and in some cases ligation of the duct. 21–23

Airway Injuries Tracheobronchial injuries occur in 0.2% to 8% of patients with blunt trauma. These inju-ries include partial or full transection of the trachea, left or right main bronchi, or lower bronchial segments. Blunt mechanisms associ-ated with airway injury include hyperextension of the neck, compression of the chest, or rapid deceleration, resulting in avulsion of the air-way. Rapid deceleration can disrupt the air-way in regions where the airway structures transition from fixed positions to more mobile ones, such as the pulmonary hilum. In 80% of cases, disruption occurs within 2.5 cm of the carina. 3 , 8 , 15 , 24

Clinical Features and Initial Management Clinical manifestations of airway disruption depend on the location of the injury. Tracheal injuries manifest with subcutaneous emphy-sema of the chest and neck, dyspnea, stridor, hoarseness, and hemoptysis. Airway injuries within the chest cavity and those affecting the main bronchi can result in pneumomediasti-num and/or pneumothorax. Both may be detectable on CXR or CT scan of the chest. 3 , 8 , 15

The management of airway injuries depends on the location and severity of injury. Tracheal injuries may be identified during endotracheal intubation or after placement of an endotra-cheal tube. Placement of the tube and inflation of the cuff can result in further tracheal disrup-tion or transection, depending on the location of injury. If the injury is bridged by the endotracheal tube, the airway may be ade-quately secured. However, if the injury is below the cuff, PPV may further disrupt the defect and result in worsening subcutaneous emphysema. 3 , 8 , 24 Bronchoscopic evaluation and assistance with placement of the endotracheal tube may be required to bridge the level of the defect and adequately secure the airway. Emer-gent surgical options to manage the airway in tracheal injury may be limited, depending on


Figure 1: Chest drain system with autotransfusion capability. This fi gure is available in color in the article

on the journal Web site, www.aacnadvancedcriticalcare.com , and the iPad. Reprinted with permission from

Atrium Medical Corporation.



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the depth of injury. Although surgical crico-thyrotomy is usually the procedure of choice for emergent surgical creation of an airway, placement of the airway through the cricothy-roid membrane may be well above the injury level, failing to adequately secure the airway. 25–29 Emergency tracheostomy may be the best option in this circumstance.

Diagnosis of Bronchial Injuries Diagnosis of bronchial injuries may be challeng-ing in patients with blunt trauma. Unlike pene-trating mechanisms, where trajectory may assist in determining underlying airway injury, blunt mechanisms provide no such clues. The findings on clinical assessment noted earlier may be pre-sent. CXR and CT of the chest may reveal pneumothorax, pneumomediastinum, or both. Persistent pneumothorax, despite insertion of a chest tube and the presence of a continuous air leak should increase suspicion of bronchial injury ( Figure 2 ). 3 , 8 , 27 , 28 , 30–33 Normally, pneumo-thorax and presence of an air leak resolve with reexpansion of the lung after placement of a thoracostomy tube. In the case of bronchial injury, the airway defect fails to seal, providing a continuous source of air leakage into the pleu-ral space. In addition, the patient may have worsening respiratory distress, as tidal volume is consistently lost through the thoracostomy tube. Other more common reasons for persis-tent pneumothorax and air leak should be ruled

out, including blockage or clotting of the thora-costomy tube, necessitating placement of a sec-ond tube. 27,28,30,31,33

The diagnosis of tracheobronchial injuries has improved with the use of spiral CT of the chest. Bronchoscopy, however, is still the definitive diagnostic tool ( Figure 3A ). 15 , 31 , 33

Management of Tracheobronchial Injuries Initial treatment of patients with these injuries includes definitive airway management, with caution exercised to prevent further disruption of the tracheobronchial structures during airway placement. Ventilation with low-tidal volume or low pressures may be necessary to prevent further disruption of the airway asso-ciated with PPV. Spontaneous breathing modes

Figure 2: Chest radiograph shows pneumothorax

on the right side despite previous placement of a

chest tube. The pneumothorax was unresolved with

a continuous air leak noted in the water seal chamber

of the chest drain, prompting suspicion of a bronchial

injury that was confi rmed during bronchoscopy.

Figure 3: Photographs obtained during bronchos-

copy show (A) bronchial laceration near the left and

right main bronchi and (B) bronchial injury after repair.

Reproduced with permission from John Kucharczuk.

This fi gure is available in color in the article on the

journal Web site, www.aacnadvancedcriticalcare.

com , and the iPad.




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such as pressure support ventilation may achieve this goal by supporting negative intrathoracic pressure associated with sponta-neous breathing, rather than the higher driving pressures associated with traditional PPV. Such management is, however, dependent on the patient’s ability to maintain the spontaneous breathing efforts necessary to use these modes. 3 , 24 , 28 , 34

Definitive repair of these injuries is based on the location and severity of injury. Some inju-ries such as those that affect less than one-third the diameter of the airway may be managed nonoperatively. Others may require thoracot-omy with surgical repair ( Figure 3B ). Insertion of a double lumen ET tube may be necessary to perform single lung ventilation on the unin-jured side, while repair of the injury takes place. 3 , 15 , 26 , 28

Pulmonary Contusions Pulmonary contusions are common in blunt chest injury and may be associated with rib frac-tures and flail chest. These injuries result from compression or rapid deceleration forces applied to the chest wall and lung parenchyma. Com-mon mechanisms of injury in the civilian sector include motor vehicle or motorcycle crashes with impact on the chest wall, pedestrian/motor vehicle collisions, and falls. 4 , 5 , 35–39

The overall impact of this energy applied to the lung is injury of the pulmonary interstitium or alveoli, resulting in bleeding into and around these structures. Localized inflamma-tion results in further damage and increases permeability of the alveolar capillary mem-brane, causing transudation of plasma-rich fluid into the alveoli. In addition, type II alveo-lar cells responsible for surfactant production are compromised, as is the function of sur-factant already present in the alveoli. The net effect is alveolar collapse, impaired gas exchange, and development of pulmonary shunt conditions. This effect may be further compounded if the patient aspirates gastric contents or blood into the uninjured lung, fur-ther worsening gas exchange. 1 , 3–5 , 36 , 37

Pulmonary Blast Injury Mechanism Blast injuries are more common in the combat setting, representing related but unique pat-terns of energy distribution that cause the underlying injury. Gas- or air-containing organs such as the lungs and bowel are vulner-able to injury from blast effect because of 3

related but distinct events. First, the blast energy creates a shearing (spalling) effect at the interface between gas and liquid in the alveoli. Second, low-density alveolar tissue is separated from heavier hilar tissue because of the differ-ent response motions to the blast. The third event occurs after the blast wave passes, result-ing in rebound or overexpansion of the alveoli. These mechanisms are distinct from injury associated with blast-associated projectiles striking the chest wall and causing underlying pulmonary injury, or deceleration injury of pulmonary structures after the victim is thrown against a stationary object. 36 , 40

Initial signs and symptoms of patients with blast injury may be similar to those of patients with general pulmonary contusion in that oxy-genation disturbances may be subtle at first, progressing over hours with decreasing oxygen saturation. Frothy sputum and frank hemopty-sis also may be present, representing more sig-nificant disruption of the alveolar capillary membrane. Mechanical ventilation may be required, though risk of systemic air embolism has been described as a potential complication of PPV as air is forced into the vascular space across the alveolar capillary disruption. 39 Reduction of peak inspiratory ventilation pres-sure may be beneficial. This reduction may be achieved through low tidal volume or pressure-targeted ventilation, as well as pressure sup-port ventilation in spontaneously breathing patients. 39

Diagnosis of Pulmonary Contusion Pulmonary contusion is diagnosed on the basis of mechanism of injury as well as results of clinical and radiological evaluation of the patient. Significant blunt force energy applied to the thorax along with the presence of rib fractures should raise suspicion of pulmonary contusion. Clinical findings may include chest pain, dyspnea, and hemoptysis. Worsening hypoxia, hypercarbia, and work of breathing may necessitate intubation and institution of mechanical ventilation. In intubated patients suctioning of blood from the endotracheal tube may be common. Increases in peak air-way and plateau pressures, as well as decreas-ing static lung compliance, also may be found. 1,5,35,37,41,42

Although CXR is a standard part of the ini-tial diagnostic evaluation, only 47% of pulmo-nary contusions may be detected on such images. Detection may increase to 92% by 24




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Figure 4: Chest radiograph (left) and computed tomography scan (right) of the chest show bilateral pulmo-

nary contusions (arrows).

hours after injury, but CXR is limited in the early identification of pulmonary contu-sions. 37 , 43–45 CT of the chest is more sensitive and specific than CXR in the initial identifica-tion of pulmonary contusion ( Figure 4 ). 43–46 Diagnosis of pulmonary contusion via ultra-sound has also been described, adding to the current application of this technology in diag-nosing thoracic injuries. 47 , 48

The severity of pulmonary contusions may worsen in the first 24 to 48 hours after injury. This worsening may be apparent on serial CXRs and CT scans of the chest. Current CT technology allows accurate diagnosis of contu-sion, including contusions that may not pro-gress to significant respiratory distress, when compared with lesions that appear on both CXRs and CT scans of the chest. 37 , 43–45 Although CXR and CT may be helpful in determining the degree of alveolar collapse, management of the patient should be based on the combined evaluation of diagnostic studies, pulmonary mechanics, and gas exchange. Such manage-ment includes the use of ventilation strategies to both support gas exchange and protect the lung from ventilator-induced lung injury. 3 , 24 , 37

Management of Pulmonary Contusion Management of patients with pulmonary contu-sions is primarily supportive. At minimum, sup-plemental oxygen should be initiated and titrated to achieve oxygen saturations of greater than 90% to 92%. Use of a high-flow/high-

humidity nasal cannula may be considered when a high fraction of inspired oxygen (F io 2 ) may be required. This method offers the advan-tage of high F io 2 delivery without the confine-ment of a high-flow mask.

Noninvasive PPV may be used in select patients with pulmonary contusion and hypox-emia refractory to supplemental oxygen. 37 , 49–51 Patients chosen for this mode of ventilation must be able to protect their airway and be free of contraindications to noninvasive ventilation (eg, inability to tolerate mask ventilation, ina-bility to cough or manage pulmonary secre-tions, and profound metabolic acidosis). In a study by Antonelli et al, 50 82% of patients with pulmonary contusion that was managed with noninvasive PPV did not require intubation. Careful reevaluation of these patients for pro-gressive respiratory failure is important to allow prompt transition to intubation and con-ventional ventilation if necessary. 49 , 51

In patients who are unable to protect their airway and/or require conventional ventila-tion, rapid airway control through intubation or surgical creation of an airway is required. In some cases, bleeding from the tracheobron-chial tree may require insertion of a double-lumen ET tube ( Figure 5 ) to isolate the injured airway for bleeding control, facilitate surgical repair, or provide independent lung ventila-tion. Uncontrolled bleeding from the airway may be controlled through the insertion of a bronchial blocker ( Figure 6 ). These devices allow balloon tamponade by passage of the




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device into the affected airway through the artificial airway with the assistance of a bron-choscope. Alternatively, selective intubation of the bronchus on the affected side by using a conventional endotracheal tube, or a double-lumen endotracheal tube, may be done to con-trol bleeding and allow injury repair. 1,3,4,24,37,42

Mechanical Ventilation Mechanical ventilation of patients with pulmo-nary contusion may present some challenges. Overall, the strategies are aimed at improving oxygenation and ventilation while protecting the lung. Patients with pulmonary contusion are at risk for development of pneumonia and acute respiratory distress syndrome. 53 , 54 The success of standard approaches to alveolar reexpansion such as high positive end-expiratory pressure (PEEP) and recruitment maneuvers may depend on the degree of consolidation in the contused region of the lung. During these maneuvers, the goal is to reexpand atelectatic regions. How-ever, such tactics may overdistend normal regions of the lung while having minimal impact on the consolidated area of contusion. This overdistention may result in ventilator-induced lung injury from volutrauma in the uninjured lung, with little improvement in the injured lung. Overdistention of normal alveoli also may compress associated pulmonary capillaries, reducing perfusion to these alveoli, and result-ing in dead space ventilation units. This com-pression also may redirect blood flow toward collapsed alveoli, worsening the existing shunt. 1 , 5 , 24 , 55

Given the degree of lung injury, lung-pro-tective ventilation strategies should aim for improving oxygenation and limiting further lung injury. This strategy includes limiting ven-tilation plateau pressure (alveolar surrogate pressure) to less than 30 cm H 2 O and prevent-ing end-tidal collapse. These goals may be achieved through the use of low-tidal-volume ventilation and application of PEEP. Low-tidal-volume ventilation uses a tidal volume of 4 to 8 mL/kg of predicted body weight. 56 Other ventilation options include pressure control ventilation, with or without inverse ratio venti-lation. Inverse ratio ventilation uses shortened expiratory times to prevent full exhalation before the next breath, which results in the accumulation of auto-PEEP (intrinsic PEEP) to recruit alveoli and prevent alveolar collapse during exhalation. 57 , 58 Variations of pressure control ventilation include biphasic (bilevel) ventilation and airway pressure release ventila-tion. Both of these pressure modes allow coex-isting spontaneous breathing efforts by patients, while maintaining the benefits of the pressure control mode of ventilation’s breath pressure and flow patterns of breath delivery. In the case of airway pressure release ventilation,

Figure 5: Double-lumen endotracheal tube used

to isolate the lung for interventions such as single-

lung ventilation or independent lung ventilation. This

fi gure is available in color in the article on the journal

Web site, www.aacnadvancedcriticalcare.com , and

the iPad.

Figure 6: (A) The bronchial blocker balloon fully in-

fl ated into the right main bronchus. (B) Fully infl ated

balloon in the entrance of the left main bronchus.

Reprinted with permission from Campos. 52




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very short expiratory times between ventilator breaths are designed to prevent alveolar collapse. 1 , 59 , 60 Other ventilation options may include high-frequency percussive ventilation or high-frequency oscillation ventilation to both recruit and protect the lung. 61 , 62

Regardless of the mode or strategy chosen, reducing tidal volume to protect the lung may result in hypercapnia. Permissive hypercapnia is the allowable increase in Pa co 2 associated with the use of lower tidal volumes to protect the lung from ventilator-induced injury. This hypercapnia may be required for a period of time until alveolar reexpansion can occur, restoring the normal lung capacity. Hypercap-nia is usually tolerated well in most patients. There are no consistently recommended titra-tion end points for hypercapnia. Hypercapnia resulting in an arterial pH as low as 7.2 is con-sidered acceptable. 63–65

In addition to the preceding ventilation techniques, isolated single-lung ventilation of the uninjured lung, or independent lung venti-lation, may be an option to customize tidal volume and PEEP to the uninjured and injured lung. 24 , 42 , 66 With both options, the injured lung can be isolated, preventing aspiration of blood and secretions into the uninjured lung. Inde-pendent lung ventilation uses 2 ventilators (1 for each lung) that can be synchronized or allowed to ventilate each lung asynchronously through a double lumen ET tube. This tech-nique is useful for severe unilateral lung contu-sions or bilateral contusions of different severity. Independent lung ventilation is often maintained until the disparities in lung mechanics between the injured lung and the uninjured lung begin to resolve. Monitoring of peak and plateau pressures, lung compliance, and radiographic findings may guide decisions to convert to whole-lung ventilation and fur-ther ventilator liberation. 24 , 66

Severe unilateral or bilateral pulmonary contusions may result in the inability to oxy-genate or ventilate the patient conventionally. In these cases, extracorporeal membrane oxy-genation (ECMO) may be required to main-tain pulmonary support and lung rest. Although ECMO is potentially beneficial, there is risk of increased bleeding into the con-tused lung associated with the anticoagulant used in the ECMO circuit. 67–69 A detailed dis-cussion of ECMO as a pulmonary support strategy is provided in the article by Schulman et al 70 in this issue.

Fluid Resuscitation in Blunt Pulmonary Injury Restoration of vascular blood volume may be required as part of the initial resuscitation of injured patients. Although restoring blood vol-ume is necessary to improve global tissue oxy-genation, overresuscitation with fluids should be avoided. Recent evidence supports balanced fluid resuscitation to achieve adequate organ perfusion while limiting the harmful effects of fluid volume overload. This balanced approach has been described in several clinical conditions including penetrating trauma, and is especially true of patients with lung injury. The adminis-tration of crystalloids to treat pulmonary contu-sion may increase pulmonary interstitial edema, worsening gas exchange. 5 , 37 , 42 , 71–73 In patients with pulmonary contusion, vascular volume optimization should be based on optimizing oxygen delivery: delivering blood components to restore blood loss and correct coagulopathy while preventing and correcting hypothermia. Crystalloid administration should be limited and should be based on reliable dynamic end points of fluid resuscitation that reflect improve-ments in cardiovascular volume and function, rather than unreliable pressure-based parame-ters such as central venous pressure and nonspe-cific physiological parameters such as heart rate and urine output. 74–76

Currently, reliable end points include echocardiography evaluation of cardiac chamber and vena caval filling volumes, eval-uation of stroke volume change with volume challenge, and evaluation of variations of stroke volume and pulse pressure to deter-mine the benefit of vascular volume replace-ment. 77–79 Pressure-based parameters such as central venous pressure and pulmonary capil-lary wedge pressure have proven consistently unreliable as surrogates for changes in vascu-lar volume. 74 , 75 Further, those pressures may be falsely elevated with the use of PPV because the positive pressure is transmitted to the venous system, which further compli-cates the use of vascular pressures as end points for fluid resuscitation. 80–82

Positioning Therapy Positioning therapy in blunt pulmonary injury is aimed at improving ventilation/perfusion matching through expansion of collapsed alve-oli and matching perfusion to the best-ventilated regions. In addition, positioning therapy assists in mobilizing blood and




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secretions for removal to further assist in achieving these goals. There are 2 opinions related to positioning patients with a unilateral lung injury. 5 , 24 , 37 , 55 When the injured lung is placed in the dependent position, bleeding may be isolated to the injured side, limiting drainage from the injured lung into the uninjured lung. In this situation, positioning the patient injured side down may afford time to control bleeding or isolate the injured lung. The other option is to place the uninjured lung in the dependent position to optimize gravitational perfusion to the uninjured or best-ventilated lung. This positioning may improve ventilation/perfusion matching on the uninjured side and improve oxygenation. In addition, this option places the injured lung in the nondependent position, pro-viding opportunity for reexpansion. 24 , 37

In either case, positioning should be based on the clinical condition of the patient and what position achieves optimal gas exchange while facilitating lung expansion. In the absence of uncontrolled hemorrhage and risk of aspiration of blood into the uninjured lung, placement of the uninjured lung in the depend-ent position will support ventilation/perfusion matching and is the best option for improving gas exchange.

This goal may be achieved through manual repositioning, the use of continuous lateral rotation beds, or by placing the patient prone. Prone positioning may be helpful with bilat-eral lung injury, where consolidation is present along the dorsal surface of the lung. Move-ment to the prone position may assist with the reexpansion of these collapsed regions and improve matching with the perfusion that remains primarily in this posterior region, even when the patient is placed prone. 83–85

Pain Management Pain associated with blunt chest injuries can be significant, often resulting in additional compli-cations associated with hypoventilation if not managed appropriately. Pain management should facilitate 3 objectives: ability to main-tain the work of breathing unassisted, partici-pation in pulmonary hygiene efforts such as coughing and deep breathing, and ability to mobilize within and out of bed as appropriate to improve ventilation and limit complications associated with immobility. Finally, if the patient requires treatment with mechanical ventilation, pain management should facilitate ventilator liberation. 86–88

Pain Management Strategies Pain management strategies for patients with blunt chest injury include a parenteral analge-sic, local and regional blocks, and epidural analgesia. Parenteral opioid analgesic agents are effective for acute pain and may be deliv-ered intermittently, continuously, or as patient-controlled analgesia. Although such analgesics are commonly used, there is a risk of overseda-tion and other opioid-associated adverse effects. Local and regional analgesia may be directed to the area of injury, reducing the need for and duration of use of other analgesics. Epidural analgesia is delivered to the epidural space, interrupting pain transmission at the dorsal horn of the spinal cord. 42 , 86–88 This tech-nique provides superior analgesia while limit-ing the systemic adverse effects of parenteral agents. Although effective, epidural catheter placement may not be possible in patients with coexisting spinal column fractures or patients who have been taking anticoagulants. Other agents such as nonsteroidal anti-inflammatory drugs may be used as well. 42 , 87

Conclusion Blunt pulmonary injuries are common and require early identification during initial assessment and resuscitation to limit associ-ated morbidity and mortality. Definitive airway management and support of oxygena-tion and ventilation should be anticipated. This may include management of hemorrhage from the bronchopulmonary tree, as well as implementation of nontraditional ventilation strategies. Fluid resuscitation should be guided by end points that reflect volume responsive-ness, such as improvement in stroke volume, to avoid an unnecessary positive fluid balance that may worsen pulmonary gas exchange. Finally, adjunctive support strategies, includ-ing pain management and positioning, are essential to improve patient’s comfort and limit pulmonary complications as well as com-plications associated with immobility.

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