ABC ofMajor Trauma

THORACIC TRAUMA- IStephen Westaby, Nigel Brayley

Many patients with catastrophic intrathoracic visceral injury such aslaceration of the heart, aorta, or major airways die at the site of incident.Those who reach hospital alive are a self selected group who should survivewith early skilled intervention. Yet evidence suggests that most patientswho die in hospital of thoracic trauma do so unnecessarily through lack ofappropriate treatment. In practice, less than 15 per cent of patients withchest injuries require surgical intervention, pathology in the remainderbeing confined to the thoracic cage and underlying lung parenchyma.Multiple rib fractures with pulmonary contusion, haemothorax, orpneumothorax can be dealt with simply and effectively by insertion of achest drain, pain relief, fluid restriction, and physiotherapy. When ignored,underestimated, or inadequately treated, however, such injuries may causedeath during surgery for seemingly more important intracranial orabdominal haemorrhage. The basis for successful management of thoracictrauma is effective cardiopulmonary resuscitation followed by earlydetection and correction of life threatening injuries.

Mechanisms and patterns of blunt thoracic trauma

Chest wall injuriesPossible thoracicvisceral injuries

Common associatedinjuries

High velocity impact (deceleration)Chest wall often intact Ruptured aorta Head andor fractured sternum Cardiac contusion faciomaxillary injuriesor bilateral rib Major airways injury Fractured cervicalfractures with anterior Ruptured diaphragm spineflail (caused by Lacerated liver orsteering wheel) spleen

Long bone fracturesLow velocity impact (direct blow)

Lateral-unilateral Pulmonary contusion Lacerated liver orfractured ribs spleen if ribs 6-12 are

fractu redAnterior-fractu redsternum

Anteroposterior-bilateral rib fractureswith or withoutanterior flailLateral-ipsilateralfractures with orwithout flailPossible contralateralfractures

Cardiac contusion

CrushRuptured bronchusCardiac contusion

Pulmonary contusion

Fractured thoracicspineLacerated liver orspleenLacerated liver orspleen

Reception and general assessment of themultiply injured patient have been dealt with inprevious articles in this series. It is imperative todetermine within the first few minutes whetheran immediately life threatening thoracic problemexists. The primary survey must take intoaccount the mechanism of injury: there aredistinct patterns of injury according to whetherthe patient has suffered high velocity, lowvelocity, crush, or penetrating trauma.Remember that the most serious intrathoracicinjuries can occur without damage to the chestwall. Diagnosis may be difficult and shoulddepend on prediction and exclusion rather thandirect manifestation of injury.

When the thoracic cage and underlying lungs are injured hypoxia andacidosis caused by untreated haemopneumothorax compound the effects ofa direct head injury and should be resolved quickly. Generally, majorinjuries such as aortic transection, major airways disruption, diaphragmaticrupture, and serious cardiac disruption are apparent in the plain chestradiograph. Such radiography should be undertaken as part of the primarysurvey and certainly before radiography of the abdomen or limbs.Remember that cardiac or major vascular lacerations with haemorrhagearrested by tamponade may rapidly become fatal during transfusion andraising ofintracardiac or arterial pressures. Ifsuch injuries are not identifiedbefore full resuscitation the patient may bleed to death rapidly as normalblood pressure is restored.

Analysis of blood gas tensions and chest radiography should beundertaken within the first 10 minutes after hospital admission in anypatient in whom an important chest injury is suspected.

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Immediately life threateningpathophysiological processes* Hypoxia and acidosis secondary to major

airway obstruction,haemopneumothorax, pulmonarycontusion, or a major circulatory disorder.Is the patient blue, tachypnoeic, cerebrallyobtunded, sweaty, or cold?

* Low cardiac output secondary tohaemorrhage in the chest or abdomen,cardiac tamponade, or profoundmetabolic deterioration. Does thepatient's colour, vital signs, and peripheralperfusion suggest this? Is there activebleeding?

* Cardiac or vascular injurythat may provefatal during resuscitation

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Decide whether the clinical findings are those expected from themechanism of injury. Determine whether the chest injury is more lifethreatening than associated head or abdominal injuries. From the physicalexamination determine whether the patient is in immediate danger orwhether it is safe to proceed with computed tomography or furtherradiological assessment of other systems.

In multiply injured patients with head injury, haemothorax, and intra-abdominal bleeding it is imperative to resuscitate the brain andmyocardium. Not infrequently the patient is moribund from cardiactamponade, upper airways obstruction, tension haemopneumothorax, orprofound haemorrhage. Securing the airway by endotracheal intubation orbronchoscopy, evacuation ofhaemopneumothorax by insertion of a chestdrain, or, in the event of tamponade or torrential haemorrhage, immediatethoracotomy must be undertaken on the basis of physical findings.

In the absence of perceptible blood pressure left anterolateralthoracotomy through the fifth interspace can be undertaken to clamp thedescending aorta and perform internal cardiac massage. This facilitatesrestoration of perfusion pressure to the brain and coronary arteries whilearresting intra-abdominal haemorrhage. If present, cardiac tamponade canbe relieved. With restoration of cardiac output to the upper part of bodyrequirement for craniotomy must be determined rapidly, beforeperforming abdominal surgery. Remember that in the presence ofpotentially lethal brain, cardiac, or aortic injury other injuries are ofsecondary importance.

The plain chest radiograph

.._-. ui

Cardiac tamponade caused by a leftparasternal stab wound.

Aortic transection caused by adeceleration accident.

Free air in the mediastinum and Ruptured left hemidiaphragm withbeneath the deep cervical fascia owing haemothorax and stomach andto tracheal transection. ruptured spleen in left pleural cavity.

Plain chest radiography is the most importantinvestigation in patients with thoracic trauma andshould be undertaken with the patient erect orsemi-erect if possible. This will enable the bestassessment of the volume of free air or blood inthe chest. In practice, patients with multipleinjuries usually undergo radiography in a supine,semi-erect, or lateral decubitus position, with thex rays passing anteroposteriorly.Most serious injuries, including cardiac

tamponade, transected aorta, lacerateddiaphragm, and major airways injury, can bediagnosed or ruled out on the basis of chestradiographs. Decide whether the radiologicalappearances are those expected from the physicalsigns and mechanism of injury. Are thereunsuspected findings? Remember that in as manyas 15 per cent of patients with fractured ribs,pulmonary contusion, and surgical emphysemabut no pneumothorax the pleural cavity has beenobliterated by previous pneumonic adhesions.Free air within the chest wall andhaemopneumothorax usually indicate superficialpulmonary laceration by fractured ribs whereasair in the mediastinum (with or withoutpneumothorax), pneumopericardium, and airdeep to the deep cervical fascia of the necksuggest tracheobronchial disruption. This isconfirmed by bronchoscopy.

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Clinical predictors of major chestinjury

* Mechanism of injury* Associated head and abdominal injuries* Superficial evidence, including seatbelt

marks, bruising on the chest, cyanosis,surgical emphysema, and swelling at theroot of the neck

* Systemic evidence of major haemorrhagein the absence of abdominal swelling ormultiple long bone injuries

* Specific clinical findings, includingtraumatic asphyxia, absent peripheralpulses, respiratory distress, cardiactamponade, tracheal displacemfent, signsof tension haemopneumothorax orpneumothorax, paradoxical chest wallmovement, and pentrating chest wounds

Immediate thoracotomy in the accidentand emergency department is restricted tomoribund patients:

* With penetrating injury who cannot beresuscitated without control ofhaemorrhage or tamponade

* With blunt trauma, in whom cardiacherniation (through a laceratedpericardium) is suspected or internalcardiac massage is required for otherreasons

* With flail or crushed chest withcardiopulmonary arrest

* With massive abdominal haemorrhage, inwhom aortic cross clamping and intra-aortic transfusion facilitates preferentialresuscitation of the brain and myocardiumand arrests abdominal bleeding

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Resuscitation

Indications for early intervention in life threaterinjuries

Common cause

Cardiac or aortic lacerationBleeding from lung or chest wall

Pr4Major airways injury or obstructionDisorded mechanics of breathing

CarPenetrating cardiac wound

Intervention

HaemorrhageInsert a chest drableeding; transfuoxygen carryingvenous pressureearly thoracotom

-ofound hypoxiaIntubate and pernpositive pressurehaemopneumothbalance; operatediaphragmatic ri

airwayrdiac tamponade

Perform immedi;or thoracotomy

Cardiac arrestHypoxia and acidosis due to low cardiac Intubate and perloutput state, altered mechanics of positive pressurebreathing, ventilation/perfusion acid-base balancimbalance, or impaired gas transfer give internal ore

massage; give ccinotropic suppor

A widened mediastinum with associated features suggests rupture of theaorta and the need for control of blood pressure and early aortography. Afractured sternum or thoracic spine also causes widening of themediastinum, as may arterial or venous injuries at the root of the neck. Awidened mediastinum together with extrapleural apical capping in bothhemithoraces strongly suggests aortic transection. Widening of the cardiacsilhouette or an abnormal globular appearance of the heart suggests anintrapericardial haematoma. In association with clinical signs of cardiactamponade this may need urgent pericardiocentesis or preferably mediansternotomy or thoracotomy if cardiac disruption is suspected.A lacerated left hemidiaphragm can normally be recognised by

identifying bowel gas within the left hemithorax, usually in association withhaemothorax. An apparent raised right hemidiaphragm suggests rightdiaphragmatic rupture as paralysis of the phrenic nerve caused by trauma isextremely rare. The possibility of a subdiaphragmatic haematoma from aruptured liver can be excluded by abdominal ultrasonography.

In the absence of clinical or radiological evidence of major intrathoracicinjury requiring early surgery treatment should be concentrated onmoderating the pathophysiological processes that result from chest walldisruption, pulmonary contusion, and intrathoracic bleeding.

Appropriate intervention in patients requiring resuscitation must bebased on the immediately life threatening problem but usually follows theABC of resuscitation principle, beginning with intubation and positivepressure ventilation if required. Securing a reliable airway may beparticularly hazardous in patients who have sustained blunt or penetratingtrauma to the root of the neck or upper chest. If laryngeal or trachealdisruption is suspected in a patient who is breathing spontaneously blindintubation may prove fatal and must give way to expert bronchoscopicnegotiation of the airway. This is preferable to tracheostomy in advance ofaccurate definition of the nature of injury. With complete trachealtransection immediate collar incision with location of the distal trachea maybe necessary.

Early correction of hypoxia and acidosis are of paramount importance,particularly in the presence of head injury or when urgent surgery forabdominal injuries must be undertaken. This can be done only on the basisofblood gas tensions and acid-base analyses. When hypoxia and acidosis areconfirmed one or more of the following steps are necessary.

* Improve the mechanics of breathing byclearing major airways obstruction or draining ahaemopneumothorax. Alleviate pain fromfractured ribs or undertake mechanicalventilation if the severity of chest wall disruption

ning thoracic and pulmonary disruption so demands* Improve oxygen transport by increasing theinspired oxygen content. Restrict the amount ofclear fluid infused and restore the circulating

Bin to assess rate of oxygen carrying capacity by blood transfusionise blood to maintain after profuse haemorrhagecapacity; measure!; perform immediate or * Improve the circulation and oxygen deliveryy if necessary by arresting haemorrhage, restoring circulating

blood volume, relieving cardiac tamponade, andform intermittent giving calcium or inotropes if necessary. Beforeventilation; drain

horax; correct acid-base restoring the systolic blood pressure toto correct >100 mg Hg rule out potentially catastrophicipture or damaged cardiac or aortic laceration and potentially fatal

secondary haemorrhage.ate or early sternotomy Accurate assessment and correction of acid-

base balance, derangement of blood gas tensions,and the circulatory state require early insertion of

form intermittenta ventilation; correct central venous and radial arterial lines. Only then,e with bicarbonate; can improvement or deterioration in conditionxternal cardiac during the first hour of resuscitation bealcium; defibrillate; givet as necessary monitored sensibly and pharmacological

intervention be assessed.

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Radiological features that suggestaortic rupture

* Widening of the superior mediastinum toB8cm in a 100cm anteroposterior supineradiograph

* Tracheal shift to the right* Blurring of the aortic outline* Obliteration of the medial aspect of the left

upper lobe (pleural capping)* Opacification of the angle between the

aorta and left pulmonary artery* Depression of the left main bronchus to an

angle <400 with the trachea

ABC principle of cardiopulmonaryresuscitation for thoracic traumaEstablish a reliable Airway-through an oropharyngeal airway; anendotracheal tube; a bronchoscope;tracheostomy

Restore the mechanics of Breathing -by artificial respiration; evacuation ofhaemopneumothorax; stabilisation ofunstable chest wall; mechanical ventilation

Resuscitate the Cardiovascular system -by intravenous infusion of crystalloid,colloid, or blood; restoring acid-base statesand electrolyte concentrations; inotropicsupport; external or internal cardiacmassage; immediate surgery to stemhaemorrhage

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Chest wall derangementManagement of rib fractures

< 5 Unilateral rib fractures

' Antipyretic oral or intravenousanalgesia, physiotherapy

v Consider local intercostalnerve block orintrapleural bupivacaine

Stable chest wallNormal blood gas tensions

Multiple unilateral rib fractures

Thoracic epidural anaesthesia,5 -> physiotherapy, mini-tracheostomy

to aspirate secretionsI ~L 4H: Consider surgical chest wall fixation

Stable or flail chest wallPoor blood gas tensions Transitiondepends on

deteriorationMultiple fractures with deformity or bilateral fractures of blood

gas teilsions

Ventilation,physiotherapyConsider surgical chest wall

l ---~~ fixation and antibiotic prophylaxisUnstable chest wallPoor blood gas tensions

The two main types of serious chest wall derangement are a functionallyimportant traumatic defect (sucking chest wound) and a flail segment. Themost extensive disruption occurs in severe crush injuries in which multiplebilateral rib fractures and fractures of the sternum coexist. Each rib fractureis associated with a blood loss of about 150 ml. With multiple fracturesblood loss may be substantial and is increased by laceration of theunderlying lung by sharp edges. The damaged chest wall may be stable, sothat with adequate pain relief breathing continues unhindered, or unstable,when the mechanics of breathing are compromised. The flail segmentmoves inwards on inspiration and consequently compromises ventilation byreducing tidal volume. Full expansion of the lung must be restored as soonas possible by covering a traumatic defect, stabilising a flail segment, anddraining a haemopneumothorax. Further management is aimed not at thechest wall itself but at preserving respiratory function.

Pain causes decreased respiratory excursion and failure to ventilate thebasal segments, resulting in atelectasis. Pain also inhibits cough so thatsecretions cannot be cleared from the bronchial tree, causing bronchialobstruction and acute respiratory failure. Pain relief is very important sothat the most effective therapeutic option, physiotherapy, can be carriedout frequently and with the patient's full cooperation.

Recent studies have shown decreased mortality in patients with extensiverib fractures with the conservative approach to pain relief compared withroutine mechanical ventilation. This also applies to patients who haveundergone surgery for concomitant abdominal or orthopaedic injuries,those with flail segments, and those with pulmonary or cardiac contusion aslong as arterial Po2 is >50 mm Hg when 50% oxygen is being inspired andvital capacity is > 10 ml/kg. Analgesia is planned to provide a central blockat the dermatome area of pain up to the level of T4. Intubation andventilation should be considered only if the arterial Po2 falls below50mm Hg with supplementary oxygen or if there is an increase inrespiratory rate to 40 breaths/min with an inability to cough.

Mechanical ventilation is important in unconscious and uncooperativepatients with severe or worsening respiratory failure despite adequateanalgesia and clearance of secretions by physiotherapy. A flail segment initself is not an indication for mechanical ventilation; the functional ratherthan the anatomical consequences of injury determine the necessity forventilatory support. Surgical intervention is only rarely indicated for fixingsternal fractures, correcting serious deformities, and evacuating anextensive clotted haemothorax or haemostasis in a severely lacerated lung.

Chest drain insertionOne, and occasionally more than one, chest drain should be inserted to

clear blood or air from the pleural cavity. Except under dire circumstanceswith tension pneumothorax a plain chest radiograph should be taken first.Surgical emphysema in the chest wall in the absence of a pneumothorax isnot an indication for chest drain insertion, and drains should never beinserted prophylactically as damage to the underlying lung in patients withan obliterated pleural cavity may prove fatal.

In practice, drains are usually inserted for combinedhaemopneumothoraces. There are several simple steps to follow.

(1) Make certain that either blood or air is interposed between the chestwall and the lung. In about 15% of patients postpneumonic fibrousintrapleural adhesions obliterate the pleural space and result in the draintransfixing the lung(2) Choose the site carefully: it will usually be between the fourth andseventh intercostal spaces, between the midaxillary and anterior axillarylines. The level at which the anterior axillary fold meets the chest wall is auseful guide. Consult the chest radiograph unless the drain is to be insertedas an absolute emergency. There is no contraindication to inserting thedrain through an area of injury, but if there is possibility of a ruptureddiaphragm with viscera in the chest the drain should be inserted high.

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Disadvantages of prolongedintermittent positive pressureventilation

* The need for prolonged intubation withtracheostomy

* The need for prolonged sedation* Inadequate nutrition* Immobility with a risk of pressure sores* Effective physiotherapy is difficult, and

repeated passage of suction catheterstraumatises the airway

Indications for drainage oftraumatic pneumothoraces

* If pneumothorax >1 5 cm (at level of thirdcoetachondral junction) whetherintermittent positive pressure ventilationis required or not

* If pneumothorax <1 5 cm but intermittentpositive pressure ventilation is requiredfor surgery as there are bilateralpneumothoraces

* If pneumothorax <1 5 cm in patients withchronic obstructive airways disease,restructive lung and chest wall disease,high spinal cord injury, or contralaterallung resection

* All tension pneumothoraces andhaemothoraces

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Chest drain insertion. (a) Penetration of the skin,muscle, and pleura. (b) Blunt dissection of the parietalpleura. (c) Exploration of the pleural cavities. (d) Tubedirected posteriorly and superiorly.

Pericardiocentesis

_:: l~~~~~~~~--

Patient with a cardiac stab wound and tamponade.The neck veins are greatly distended despite bloodloss.

The illustration of chest drain insertion was prepared by thedepartment of education and medical illustration services atSt Bartholomew's Hospital.Mr Stephen Westaby, FRCS, is consultant

cardiothoracic surgeon, John Radcliffe Hospital, Oxford,and Mr Nigel Brayley, FRCS, is registrar in accident and

emergency medicine, Northampton General Hospital.The ABC of Major Trauma has been edited by

Mr David Skinner, FRCS; Mr Peter Driscoll, FRCS; andMr Richard Earlam, FRCS.

Avoid the anterior approach in the second interspace as this transfixes thetwo major accessory respiratory muscles-the pectoralis major and minor.If an apical drain is required because of intrapleural adhesions towards thebase then the true apical approach above the scapula and into the firstinterspace posteriorly is preferred. It is a fallacy that the drain must be in abasal position to drain blood and in an apical position to drain air.(3) Choose a size 28 or 32 Argyle chest drain-smaller drains will rapidlyocclude with blood clot. An established haemothorax will not drain andrequires surgical evacuation.(4) In conscious patients use between 10 and 15 ml of 1% lignocaine andinfiltrate the periosteum on the upper border of the rib at the choseninterspace. Advancing the needle above the rib, the pleura should beinfiltrated, and passage of the needle into the pleural cavity confirms thepresence of free air or blood on aspiration. The needle can be left in situ sothat the precise area of anaesthetic infiltration is not lost when the skin iscleansed with povidone-iodine solution.(5) Use a scalpel to incise the chest wall about 2 cm beneath the proposedsite of pleural incision, so that the drain track leads the drain to the apex ofthe pleural cavity. The scalpel should find the rib below the interspace to bebreached, then the remainder of the track be completed through to thepleural cavity with artery forceps. This route avoids the intercostal nerveand, more importantly, the vessels that are protected underneath the ribs.The drain slides easily through' the track and into the pleural cavity, whenblood or air will'flash-fill the tube. Do not be concerned about allowing air toenter along the drains; this will be evacuated immediately when the lungexpands and there is underwater sealed drainage.(6) When the drain is in position it is sutured with at least a zero gauge silkor propylene suture to prevent displacement. A pursestring suture'isapplied around the site.(7) Always apply negative pressure to chest drains to ensure evacuation ofcontinued haemorrhage or air leak. Never clamp the drain in the presence ofa brisk air leak. A Thompson or Tubbs-Barrett suction machine isnecessary to ensure large volume suction at a negative pressure of 15-20 cm H20. The Roberts suction pump should not be used as it will takeonly a small volume and may constitute an obstruction in the case of rapidair leak.(8) Check the position and effect of the drain in a plain chest radiograph.Note the initial volume of blood evacuated and the continued rate ofdrainage on suction. Assess the volume of air leak. The need forthoracotomy is determined by the rate of bleeding or air leak through thedrain during suction. In most patients the intercostal drain is the definitiveintervention.

Pericardiocentesis is of little therapeutic value and has caused deaththrough cardiac laceration. In cardiac tamponade there is a fine balancebetween internal and external cardiac pressures that preventsexsanguination. The blood within the pericardium is usually clotted andcannot be aspirated. If the patient is moribund immediate thoracotomy ismore important than attempted pericardial aspiration. Such aspiration maysometimes be undertaken on diagnostic grounds when two dimensionalechocardiography is not immediately available. A transdiaphragmaticapproach is undertaken by inserting a wide bore needle of at least 15 cmlength from a site between the xiphisternum and left costal margin, aimingthe tip of the needle cautiously towards the base of the pericardium alongthe line of the left sternal margin. The syringe is carefully aspirated duringthe course ofinserting the needle until either altered blood rapidly fills it orthe myocardium can be felt on the tip of the needle. Serious laceration of theright or left ventricles is unusual, though damage to the posteriordescending branch of the right coronary artery is possible. To increaseappreciably the stroke volume in cardiac tamponade at least 100 ml of bloodshould be aspirated. This may cause further fatal haemorrhage by raisingthe intracardiac pressure and disrupting the tamponade effect. Cardiacdisruption caused by either blunt or penetrating trauma requires urgentsurgical repair.

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Indications for elective thoracotomy* Initial chest drain insertion yields >1250 ml of

blood immediately or >1000 ml plus 250 ml inthe first hour or if 250 ml is drained in threeconsecutive hours with no decreasing trend

* Cardiac tamponade, even if pericardiocentesisrelieves symptoms

* Massive air leak when pneumothorax persistsdespite adequate drainage, suggesting majorbronchial or tracheal injury. Bronchoscopy isperformed to confirm the diagnosis and clearblood and secretions

* All transmediastinal wounds* Chest wall defects and diaphragmatic lacerations* Clotted haemothorax (to expand the underlying

lung and prevent empyema or fibrothorax);consider after 48 to 72 hours' drainage.(Enzymatic clot lysis is seldom successful)

* Combined thoracic and abdominal woundsbefore laparotomy except where entry and exitwounds preclude heart or great vessel injury orwhen the source of major haemorrhage isabdominal

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