CTVS 57 Chest Injury Pneumothorax

• Zone I
• - From the thoracic inlet to the cricoid cartilage
• - Contains large vascular structures as well as the trachea and esophagus.

• zone II
• - from the cricoid cartilage to the angle of the mandible
• - the most accessible surgically and contains the carotid and vertebral arteries, jugular veins, and structures of the aerodigestive tract.

• Zone III
• - between the angle of the mandible and the base of the skull.
• - include blood vessels that are difficult to expose surgically.

• Although zone II injuries traditionally mandated operative exploration, it has since been recognized that only those patients with evidence of active bleeding or an obvious aerodigestive injury require surgery.
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Chest injuries can be classified as blunt or penetrating. Blunt and penetrating injuries have different pathophysiologies and clinical courses.

Specific types of injuries include:

• 1. Injuries to the chest wall and injuries involving the pleural space
• Chest wall contusions or hematomas.
• Rib fractures
• Flail chest
• Sternal fractures
• Fractures of the shoulder girdle
• Pneumothorax
• Hemothorax
• Hemopneumothorax

• 2. Pulmonary injury (injury to the lung) 
• Pulmonary contusion
• Pulmonary laceration

• 3. Injury to the airways
• Tracheobronchial tear

• 4. Cardiac injury
• Pericardial tamponade
• Myocardial contusion
• Traumatic arrest

• 5. Blood vessel injuries
• Traumatic aortic rupture, thoracic aorta injury, aortic dissection

• 6. Injuries to other structures within the torso
• Esophageal injury (Boerhaave syndrome)
• Diaphragm injury

• 1. Pneumothorax and Hemothorax-
• - On a chest radiograph, a pneumothorax appears as a lucency peripheral to the standard lung markings
• - Chest CT identifies - rib and sternal fractures, occult pneumothorax
• - Treatment of pneumothorax is by placement of a tube thoracostomy
• - Hemothoraces should be drained if the quantity of blood in the pleural space will cause lung entrapment as the hematoma matures.
• - Hemothoraces that do not resolve after insertion of a tube thoracostomy may require thoracoscopic drainage and decortication.
• - The management of a chest tube includes drainage until any pulmonary air leak has resolved and tube output is not excessive
• - Occult pneumothoraces with no respiratory compromise - observation and a repeated chest radiograph 12 to 24 hours later to be sure that the pneumothorax has not expanded
• - Significant subcutaneous air often suggests ongoing pulmonary air leak, and chest tube placement should be highly considered.

• 2. Rib fractures - 
• - Manage with adequate analgesia to allow optimal pulmonary toilet and to promote comfort
• - IV narcotics is often adequate in mild and moderate cases, but in severe cases, patients benefit from epidural analgesia.
• - Aggressive pulmonary toilet, including deep breathing, frequent coughing, and incentive spirometry, should be encouraged.

• For hemothorax -  posterior to the lung.
• For pneumothorax - anterior hemithorax

• Flail chest occurs when three or more adjacent ribs are each fractured in two places, creating one floating segment comprised of several rib sections and the soft tissues between them.
• Stove in chest is depression of a portion of chest wall due to severe chest injury, otherwise features and management are like flail chest. 
• This unstable section of chest wall exhibits paradoxical motion (ie, it moves in the opposite direction of the uninjured, normal-functioning chest wall) with breathing, and is associated with significant morbidity from pulmonary contusion.
• Abnormal motion can be difficult to detect making the diagnosis difficult.
• Initial management of flail chest consists of oxygen and close monitoring for early signs of respiratory compromise, ideally using both pulse oximetry and capnography in addition to clinical observation.
• Stabilization of the segment with manual or object pressure restricts chest wall expansion thereby interfering with proper respiratory mechanics and is no longer used. Use of noninvasive positive airway pressure by mask may obviate the need for endotracheal intubation in alert patients. Patients with severe injuries, respiratory distress, or progressively worsening respiratory function require endotracheal intubation and mechanical ventilatory support.

• - Injury include pulmonary contusion and laceration.
• - The drainage of large amounts of blood or air from a tube thoracostomy is often the first indication of a pulmonary injury
• - Diagnosis is by chest x-ray and Chest CECT - Lung contusions may be present on the initial chest radiograph but typically require time to become visualized. Pulmonary contusions that are identified early on chest film are frequently severe and often rapidly progress to respiratory failure.
• - Difference between contusion and atelectasis - Atelectasis does not cross pulmonary fissures, whereas contusions are not limited by ventilatory segments
• - Thoracotomy may be required for lung injury when large quantities of blood or air drain from a chest tube.
• - The decision to operate needs to be based on the likelihood of ongoing bleeding. For this reason, ongoing drainage of blood from the chest tube is more important than the amount of initial output. Bleeding from the pulmonary parenchyma is controlled through suture ligation of bleeding vessels. When larger segments of lung are injured, pulmonary resection is occasionally required through either an anatomic or nonanatomic approach.
• - Pulmonary contusion often requires little more than supportive care. Patients should be monitored for hypoxemia, increased work of breathing, and agitation, which indicate respiratory decompensation that often requires intubation and mechanical ventilation.

• The location of penetrating injury on initial examination will often be suggestive of cardiac injury.
• Patients may present in extremis with pericardial tamponade or bleeding into one of the hemithoraces.
• Clinical features of pericardial tamponade (Beck’s triad) - hypotension with distended neck veins and muffled heart sounds
• Ultrasound - for assessment of the pericardium
• For cardiac injuries that cause cardiovascular collapse, a left anterolateral thoracotomy is performed in the emergency department as previously described. When time permits, most cardiac injuries are best approached through a median sternotomy.
• Injuries to the atria - grasped with a Satinsky clamp and then closed with sutures

For those with cardiac contusion - monitoring, ECG, ECHO, treatment of arrhythmia, treatment of cardiogenic shock

• Blunt diaphragmatic injuries occur in only 1.6% of blunt thoracic injuries and are believed to be a result of a rapid increase in intra-abdominal pressure during an anterior impact that causes a blow-out of the diaphragmatic tissue.
• The left side of the diaphragm is the injured location in approximately 75% of the cases because of the coverage of the right side with the liver.
• Despite the low incidence, the mortality is significant at 20.9%, probably because of the high energy required to create a blunt diaphragmatic rupture.
• The natural history of these injuries includes progressive enlargement with herniation of abdominal viscera into the chest.

• Injuries to the diaphragm can be a diagnostic challenge and require a high index of suspicion, even with the most subtle indicators.
• During exploration, following the trajectory of the injury will usually allow identification of the diaphragmatic defect. Blunt injuries can be more elusive.

• The chest radiograph may demonstrate the presence of abdominal viscera, most commonly the stomach, within the chest, although this finding may be absent in a significant number of injuries.
• Chest and abdominal CT scans may demonstrate the presence of abdominal viscera in the chest or an abnormality of the diaphragm itself, such as thickening, elevation, or a defect.

Given the challenge of diagnosis, operative exploration may be required when imaging is suggestive. In patients who have no other indication for laparotomy, video-assisted thoracoscopy or cautious laparoscopy conducted to avoid tension pneumothorax may offer less invasive means of visualizing the diaphragm.

• Treatment -
• - Débriding nonviable tissue and then closing the defect.
• - Closure is performed with a single layer of nonabsorbable suture incorporating large full-thickness bites of healthy diaphragmatic tissue. It is important to obtain hemostasis because diaphragmatic injuries can bleed significantly from branches of the phrenic artery that can be exposed at the edges of the tear. Large areas of tissue loss are rare in traumatic rupture but, when present, may require reconstruction with a prosthetic.

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• 1. Salvageable postinjury cardiac arrest:
• - Patients sustaining witnessed penetrating trauma to thetorso with <15 min of prehospital CPR
• - Patients sustaining witnessed blunt trauma with <10 min of prehospital CPR
• - Patients sustaining witnessed penetrating trauma to theneck or extremities with <5 min of prehospital CPR

• 2. Persistent severe postinjury hypotension (SBP ≤60 mmHg) due to:
• - Cardiac tamponade
• - Hemorrhage—intrathoracic, intra-abdominal, extremity,cervical
• - Air embolism

• 1. More than 1500 mL of blood drained on chest tube insertion
• 2. More than 300 mL/hr of drainage for 3 consecutive hours.
• 3. Massive air leak with associated pneumothorax
• 4. Drainage of esophageal or gastric contents from the chest tube.

Penetrating trauma: CPR >15 min and no signs of life (pupillary response, respiratory effort, motor activity)

Blunt trauma: CPR >10 min and no signs of life or asystole without associated tamponade

• American-European Consensus Conference Committee, 1994 definition requires
• - the acute onset of diffuse bilateral pulmonary infiltrates by chest radiograph;
• - PaO2/FiO2 ≤300 for ALI and ≤200 for ARDS; and
• - Pulmonary artery wedge pressure (PAWP) ≤18 or no clinical evidence of left atrial hypertension.

• The Berlin definition,2012 resulted in the following modifications:
• - a criterion of less than 7 days was used to define acute onset;
• - the requirement of pulmonary artery wedge pressure was removed. Clinical judgment for characterizing hydrostatic pulmonary edema suffices, unless there is no apparent ARDS risk factor, in which case an objective evaluation is required;
• - the category of acute lung injury was removed, and
• - ARDS was divided into three categories of severity based on the P/F ratio - mild (from 201 to 300), moderate (from 101 to 200), and severe (≤100  mmHg)

• Acute deterioration of pulmonary functions (pulmonary edema, pneumonia, AE of COPD)
• Sepsis following trauma
• Multiple blood transfusions
• Severe burns
• Severe pancreatitis
• Near-drowning,
• Drug reactions
• Inhalation injuries.
• Large volumes of fluid used during post-trauma resuscitation.

• Vascular congestion occurs with alveolar collapse, edema, and inflammatory cell infiltration.
• The underlying mechanism is increased pulmonary capillary permeability with extravasation of intravascular fluid and protein into the interstitium and alveoli.
• The leukocyte is the most prominent mediator of this injury.

• Often begin within two hours of an inciting event, but can occur after 1–3 days.
• Dyspnea
• Tachyypnea 
• Hypoxemia due to abnormal ventilation

• Treatment is supportive and directed toward improving oxygenation.
• Maintaining an inspired oxygen concentration as low as possible and positive end-expiratory pressure (PEEP) as low as possible to maintain adequate oxygenation and carbon dioxide exchange is helpful.
• Tidal volumes and PEEP are kept low; however, increased PEEP may be needed in selected patients to facilitate oxygenation.
• Based on a more recent meta-analysis, prone or rotational therapy may improve outcomes of these patients

• Patients with ARDS are at high risk for complications.
• - Related to mechanical ventilation - pulmonary barotrauma, nosocomial pneumonia
• - Related to critical illness and being in the intensive care unit - delirium, deep venous thrombosis
• - Stress ulceration -  gastrointestinal bleeding
• - Catheter-related infections

• Air in the pleural cavity (ie, interspersed
• between the lung and the chest wall).

• Primary spontaneous pneumothorax (PSP) - occurs in otherwise healthy patients, related to smoking,
• Secondary pneumothorax (SSP) - associated with underlying lung disease. Subpleural blebs and bullae are found at the lung apices at thoracoscopy and on CT scanning in up to 90% of cases of PSP

• - The typical symptoms of chest pain and dyspnoea
• - Signs - reduced lung expansion, hyperresonant and diminished breath sound
• - If tension pneumothorax - cyanosis, sweating, severe tachycardia and tachypnea and hypotension
• - Symptoms in PSP may be minimal or absent. In contrast, symptoms are greater in SSP, even if the pneumothorax is relatively small in size.
• - The presence of breathlessness influences the management strategy.
• - Severe symptoms and signs of respiratory distress suggest the presence of tension pneumothorax.

• Standard erect chest x-rays in inspiration are recommended for the initial diagnosis of pneumothorax, rather than expiratory films.
• CT scanning - ‘gold standard’ in the detection of
• small pneumothoraces and in size estimation

• In defining a management strategy, the size of a pneumothorax is less important than the degree of clinical compromise.
• The differentiation of a ‘large’ from a ‘small’ pneumothorax continues to be the presence of a visible rim of >2 cm between the lung margin and the chest wall (at the level of the hilum).
• A 2 cm radiographic pneumothorax approximates to a 50% pneumothorax by volume.
• Guidelines from the USA estimated the volume of a pneumothorax by measuring the distance (>3 cm) from the lung apex to the cupola, but this method would tend to overestimate the volume in a localised apical pneumothorax.

• Patients with pre-existing lung disease tolerate a pneumothorax less well, and the distinction between PSP and SSP should be made at the time of diagnosis to guide appropriate management.
• Breathlessness indicates the need for active intervention as well as supportive treatment (including oxygen).
• The size of the pneumothorax determines the rate of resolution and is a relative indication for active intervention.

• Tension or bilateral pneumothorax - Chest tube drainage, supplemental high flow oxygen.
• Large PSP without symptoms - Observation
• Small PSP without significant breathlessness - Observation. These patients can be discharged with early outpatient review. Clear written advice to return in the event of worsening breathlessness.

• Needle (14-16 G) aspiration is as effective as large-bore (>20 F) chest drains and may be associated with reduced hospitalisation and length of stay.
• Needle aspiration should not be repeated unless there were technical difficulties.
• Following failed NA, small-bore (<14 f chest  drain insertion is recommended).
• Large-bore chest drains are not needed for pneumothorax.

• All patients with SSP should be admitted to hospital for at least 24 h and receive supplemental oxygen.
• Most patients will require the insertion of a small-bore chest drain.
• Needle aspiration is less likely to be successful in SSP.
• In cases of persistent air leak or failure of the lung to reexpand, an early (3-5 days) thoracic surgical opinion should be sought.
• The air leak is less likely to settle spontaneously, so that most patients will require active intervention.

• Chemical pleurodesis can control difficult or recurrent pneumothoraces but, since surgical options are more effective, it should only be used if a patient is either unwilling or unable to undergo surgery.
• Open thoracotomy and pleurectomy remain the procedure with the lowest recurrence rate (approximately 1%) for difficult or recurrent pneumothoraces.
• Video-assisted thoracoscopic surgery (VATS) with pleurectomy and pleural abrasion is better tolerated but has a higher recurrence rate of approximately.

• Air travel should be avoided until full resolution.
• Diving should be permanently avoided unless the patient has undergone bilateral surgical pleurectomy and has normal lung function and chest CT scan.

It arises as a result of the development of a one-way valve system at the site of the breach in the pleural membrane, permitting air to enter the pleural cavity during inspiration but preventing egress of air during expiration, with consequent increase in the intrapleural pressure such that it exceeds atmospheric pressure for much of the respiratory cycle. As a result, impaired venous return and reduced cardiac output results in the typical features of hypoxaemia and haemodynamic compromise

Treatment is with oxygen and emergency needle decompression. The cannula usually being introduced in the second anterior intercostal space in the mid-clavicular line.

For details on pleural effusion, pneumothorax and empyema, refer  BTS Pleural Disease Guideline 2010.