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CHEST TRAUMA

* Trachea Lungs Bronchi Mediastinum

BOUNDARIES Of The Chest

Superiorly => clavicles Inferiorly => diaphragm Laterally => rib cage

Anteriorly => sternum Posteriorly => vertebral bodies & ribs

Structures Injured
Any organ in chest potentially susceptible especially to penetrating trauma

Contents Of Thoracic Cavity

Chest wall and ribs. Lungs and pleura. Great and thoracic vessels. Heart and mediastinal structures. Diaphragm

Esophagus Thoracic duct Tracheobronchial system


Other Organs At Risk
Thoraco-abdominal injury any wound below nipples in front and inferior scapula angles dorsally may result in intra abdominal injury.

OTHER ORGANS AT RISK

Peritoneal viscera Liver Spleen Stomach Colon & small intest. Biliary system Retro-peritoneum kidneys

Resulting Injuries

Rib fractures Sternal fractures Subcutaneous emphysema Open or Closed Pneumothorax - unilateral / bilateral Hemothorax Hemopneumothorax Pneumo-mediastinum Pulmonary contusion Myocardial contusion Diaphragmatic rupture

* Chest injuries may result from: Vehicle accidents. Falls. Gunshot wounds. Crush injuries. Stab wounds.

* Second leading cause of trauma deaths after head injury. Accounts for 25% of all trauma deaths. 2/3 of deaths occur after reaching hospital. -Vital Structures Serious pathological consequnces: hypoxia, hypovolaemia, myocardial failure. Abdominal injuries are common with chest trauma.

Mechanism of Injury

Either: direct blow (e.g. rib fracture) compression injury Rib fracture is the most common sign of blunt thoracic trauma Fracture of scapula, sternum, or first rib suggests massive force of injury. Mostly managed non-operatively.
Blunt injuries

BLUNT



Penetrating injuries E.g. Gunshot or stab wounds etc. Primarily it might affect peripheral lung Haemothorax. Pneumothorax. Cardiac, great vessel or oesophageal injury.

Mechanism of Injury

PENETRATING Low energy Medium energy High energy

Penetrating (Low energy)

Impalements Knife wounds => disrupts only structures penetrated

Penetrating (Medium energy)

Bullet wounds from most handguns

Penetrating (High energy)

From military weapons+ Shotguns (low velocity) Transfers kinetic energy to tissues => cavitation => high velocity. Amount of tissue damage proportional to amount of energy exchanged between the penetrating object and the body part.

PENETRATING

Pathophysiology
Quite serious


1. HYPOXIA / HYPOVENTILATION
Primary acute killer of trauma patients inadequate delivery of O2 to tissues.

Signs of HYPOXIA

Increased RRChange in breathing pattern (shallow)Anxious behaviorPoor air movementDilated pupilsCyanosis – (late sign)

2. Hypovolemia

Inadequate intravascular volume => BLOOD LOSS

3. Ventilation / Perfusion Mismatch

Contusion Hematoma Alveolar collapse

4. CHANGES IN INTRATHORACIC PRESSURE RELATIONSHIPS

- Tension pneumothorax - Open pneumothorax

5. METABOLIC ACIDOSIS

Hypoperfusion of tissues (shock)

MANAGEMENT

ABCs PRIMARY SURVEY Secondary Survey 4. Definitive care

2. PRIMARY SURVEY

Tension pneumothorax Massive hemothorax Open pneumothorax Cardiac tamponade Flail chest
=> Aim to identify & treat immediately life threatening conditions

* Assess the casualty

Identify signs and symptoms Airway Breathing Circulation

* Signs Indicative Of Seriouse Chest Injury

Shock Cyanosis Hemoptysis Chest wall contusion Flail chest Open wounds Distended neck veins Tracheal deviation Subcutaneous emphysema

* Assess Vital Signs

Pulse Blood pressure Respiratory rate

* Assess the Skin

Pallor-pale Cyanosis Open wound Ecchymosis-bruising

* Assess the Neck

Position of trachea Subcutaneous emphysema Jugular venous distention Penetrating wounds

* Assess the Chest

Contusions Tenderness Asymmetry Open wounds or impaled objects Crepitation Paradoxical movement

* Lung sounds Absent or decreased Unilateral Bilateral Bowel sounds in chest

* Percussion Hyperresonance (pneumothorax-tension pneumothorax) Hyporesonance (hemothorax)

* Compare both sides of the chest at the same time when assessing for asymmetry.

* Feel carefully and listen closely for subcutaneous emphysema.

* Heart sounds Muffled (cardiac tamponade) Distant


Invistigaions CXR => basis for initiating other investigations => UPRIGHT if possible

FAST

Focused Abdominal Sonography for Trauma (FAST) - All hemodynamically unstable blunt trauma pts

Cat Scan

Becoming a primary diagnostic tool

3.Detailed Secondary Survey

May show: Simple pneumothorax Hemothorax Pulmonary contusion Myocardial contusion Blunt aortic injury Rib fractures Diaphragmatic rupture

4. Definitive care Most life threatening injuries txd by - Airway control - Chest tube Usually operative

Subcutaneous emphysema

Rib Fracture

* Rib Fracture

Most common chest injury Especially common in elderly Fractures of the Scapula or the first or second rib requires a significant force This should alert you to the possibility of major thoracic vascular injury 20-30% of patients with fractures of the 1st or 2nd ribs die of associated injuries, 5% die of a ruptured aorta

Ribs form rings Consider possibility of break in two places. Fractures of 8th to 12th ribs can damage underlying abdominal solid organs: Liver Spleen Kidneys

* Signs and Symptoms Localized pain, tenderness Increases when patient: Coughs Moves Breathes deeply Chest wall instability Deformity, discoloration - Crepitus Associated pneumo or hemothorax

*
Management Simple Rib Fracture Pain Management (PCA) Monitor for pneumothorax or hemothorax Encourage deep breathing, Patients will fail to breath deeply and cough, resulting in poor clearance of secretions ( Pulmonary toilet) . Monitor elderly and COPD patients carefully

* Flail Chest

Flail chest


* Usually 2 fractures per rib in at least 2 ribs or more or separation of sternum from ribs. Produces free-floating chest wall segment (Segment of chest wall that does not have continuity with rest of thoracic cage). Segment does not contribute to lung expansion. Disrupts normal pulmonary mechanics. Accompanied by pulmonary contusion in 50% of patients with flail chest. Usually secondary to blunt trauma. More common in older patients.

* Flail segment moves with Paradoxical motion May NOT be present initially due to intercostal muscle spasms Be suspicious in any patient with chest wall: Tenderness Crepitus
Signs and Symptoms


Force also causes pulmonary contusion Observe for hemo or pneumothorax Pain from injury causes increased hypoxia

* Consequences Pain, leading to decreased ventilation Increased work of breathing Contusion of lung

* Treatment

Establish airway Administer oxygen or Assist ventilation Analgesia for pain (IV Morphine) Initiate IV - may need to limit fluids Monitor heart for myocardial trauma Stabilize chest wall ,manual pressure to stabilize flail segment, then apply bulky dressing

*

Operative fixation not usually required (historical)

Lung Injuries
Pneumothorax Hemothorax

* Pneumothorax

It is accumulation of air within space between visceral and parietal pleura. Partial or complete lung collapse occurs. Severity of symptoms depends on size of pneumothorax, speed of lung collapse.

* Pneumothorax (closed)

Pneumothorax

* May be caused by blunt trauma or may be spontaneous Over pressurization ( eg. blast, diving) May occur spontaneously following: Exertion Coughing Air Travel

* Signs and symptoms

Pleuritic chest pain, Pain on inhalation Dyspnea Decreased or absent breath sounds Hypertympany to percussion

* Management Administer oxyge Chest tube

Open Pneumothorax
Open sucking chest wound allows free passage of air into and out pleural cavity => effective ventilation impaired => hypoxia

Signs & Symptoms Penetrating chest wound Decreased breath sounds Sucking sounds on inspiration

* Open Pneumothorax

Management Cover site with sterile occlusive dressing taped on three sides. High flow O2. Chest tube.


*

Tension Pneumothorax

One-way valve forms in lung or chest wall, created from either penetrating or blunt trauma . Air enters thoracic space but cannot escape, pressure builds and further collapses the lung and forces mediastinum and heart away from effected lung. May also compromise good lung.

Tension Pneumothorax

Air pushes over heart and collapses lung
Heart compressed not able to pump well
Air outside lung from wound

Collapses ipsilateral lung

Displaces mediastinum to opposite side

Compresses opposite lung

Decreases venous return

Tension Pneumothorax

Signs & Symptoms sever dyspnea ( air hunger) chest pain tachycardia tracheal deviation absent breath sounds hyper-resonant percussion JVP Restlessness, anxiety, agitation Cyanosis Subcutaneous emphysema


Surgical emergency Rx: emergency decompression before CXR Either large bore cannula in 2nd ICS, MCL or insert chest tube

Immediate decompression Confirmation Auscultaton & Percussion Pleural Decompression 2nd intercostal space in mid-clavicular line TOP OF RIB Consider multiple decompression sites if patient remains symptomatic Large over the needle catheter: 14ga Administer oxygen chest tube as definitive tx

* Hemothorax

Blood in pleura space common result of major chest wall trauma Present in 70 to 80% of penetrating & major non-penetrating chest trauma

* Signs and Symptoms Decreased breath sounds Dullness to percussion Dyspnea Ventilatory failure
Shock precedes ventilatory failure


* Signs and Symptoms Rapid, weak pulse Cool, clammy skin Restlessness, anxiety Thirst Chills Hypotension Collapsed neck veins

* Management Assist breathing with high concentration O2 Decompression by Chest tube (most need just that). Bleeding may stop when lung re-expands

Massive Hemothorax

Loss of 1500 cc blood or 200 cc per hour from the chest tube Pleural cavity hold 3 liters blood 200cc in chest cavity seen on CXR 90% from internal mammary or intercostals 10% from pulmonary vessels


* Signs and symptoms Hypotension from blood loss or compression of great vessels Dullness to percussion Decreased breath sounds Anxiety or confusion secondary to hypovolemia or hypoxia


* Managemen oxygen Initiate IV to carefully replace fluids Chest tube Thoracotomy

* Pulmonary Contusion

Common injury produced by blunt trauma, which may be potentially lethal Most common chest injury in children Bruising of lung can produce marked hypoxemia Usually develops over 24 hours Can occur with or without laceration of parenchyma

Results from: Leakage of blood and fluid into interstitial spaces of lung - Significant inflammatory reaction to blood components in the lung

Pathophysiology

Loss of normal lung structure & function leads to - poor gas exchange - increased pulmonary vascular resistance - decreased lung compliance

Complications

Atelectasis Pneumonia ARDS Respiratory failure

Diagnosis

Parenchymal infiltrate seen in CXR adjacent to injured chest wall

Diagnosis

No real clinical findings especially initially dyspnea chest wall contusions / abrasions



Treatment
MOSTLY supportive - usually resolve in 5-8 days. - O2 + observation in milder cases. - Pain control to allow: - adequate ventilation and better management of secretions. - Fluid restriction. - Intubation + mechanical ventilation if respiratory distress present.

Indications for intubation Respiratory distress Co-morbidities esp. lung disease Other injuries– intra-abdominal

2. PRIMARY SURVEY

Flail chest Open pneumothorax Tension pneumothorax Massive hemothorax Cardiac tamponade
=> Aim to identify & treat immediately life threatening conditions

* Myocardial Contusion

Potentially lethal lesion resulting from blunt chest injury. Usually associated with fractures of the sternum. Any severe anterior chest injury.

*

Difficult To Dx => HIGH LEVEL OF SUSPICION Sign & Symptoms:- chest pain, dysrhythmias, cardiogenic shock. May mimic a myocardial infarction. ALL pts with pattern of injury must have an ECG

Diagnosis

Ectopy ST elevation Tachycardia Enzymes may be normal


Management Administer oxygen Analgesi. ECG monitoring, pulse oximetry (if availabl). Monitor in ICU & treat dysrhythmias Serial enzymes

* Cardiac Tamponade

Cardiac tamponade


*

* Usually secondary to penetrating trauma Blood rapidly collects between heart and pericardium, this pressure compresses the ventricles and prevents the ventricles from filling, which decreases cardiac output. Small amounts of fluids <100ml can cause this

Signs and Symptoms

Shock JVP Dyspnea Beck’s triad = minority of pts- Distended neck veins- Muffled heart sounds- Hypotension

* Management administer oxygen Initiate IV - a bolus of electrolyte solution (500-1000 ml) may increase filling of the heart and increase cardiac output Rapidly fatal and not easily treated in field Initiate cardiac monitoring

Treatment

Volume resuscitation. Pericardiocentesis. Surgery: - Pericardial window - Sternotomy - Thoracotomy

Diaphragmatic (Rupture) Tears

Traumatic herniation of abdominal contents into the chest

Mostly on left side

Liver “protective” on right side

Frequent injury in thoracoabdominal trauma Can result from a severe blow to abdomen 15% stab wounds 46% GSW 15% greater than 2cm long

Signs and symptoms

No distinctive signs / symptoms seen High index of suspicion needed especially with mechanism of injury. May be no immediate herniation of abdominal contents. Abdomen can appear scaphoid dyspnea with diminished breath sounds cyanosis shoulder pain bowel sounds in lower chest

Treatment

Up to 13% acute injuries missed initially 85% presenting in 3 years as - obstruction or with - decreased cardio / pulmonary reserve Goal of treatment: - Maintain adequate oxygenation => intubate - NG decompression of stomach

Diaphragmatic Rupture- Surgery

Esophageal Injuries
Most due to penetrating trauma
Diagnosis - Difficult - If delayed => rapid sepsis & high mortality - Requires aggressive investigation - Radiography - Endoscopy - Thoracoscopy Treatment - Thoracotomy, etc.


Thoracic Duct Injuries
Accompany thoracic vessel injuries Noted much later i.e. not in acute phase Huge morbidity due to severe nutritional depletion Mn => initially aggressive and nonoperative = hyperalimentation => TPN and if not sealed in 5-7 days surgical intervention

* Traumatic Aortic Rupture

Viewed from behind


* Most common cause of deaths in high speed MVA and falls from heights, 90% die immediately Diagnosis is difficult in the field High index of suspicion in above types of accidents


Often rapidly fatal Only 10% survive to hospital Only 20% survive > 1 hour 90% who reach hospital will die EARLY DX and aggressive tx best chance

Diagnosis

Mediastinum > 8cm wide Blurring of aortic knob

Treatment

Operative repair



* Tracheobronchial Tree Injury
Results from blunt or penetrating trauma Penetrating injuries frequently have associated major vascular injuries Presenting signs include: Dyspnea Hemoptysis Subcutaneous emphysema of chest, neck, or face Associated pneumothorax or hemothorax

* Management Administer oxygen Observe for pneumothorax/hemothorax

* Traumatic Asphyxia
Severe compression injury to the chest Compression of heart and mediastinum Signs and symptoms Cyanosis and swelling of the head and neck Lips and tongue may be swollen Conjunctival hemorrhage may be evident Body below the injury remains pink


*

* Impalement Injuries

Caused by penetrating object (s) DO NOT remove object Management Ensure airway and oxygen Stabilize object Initiate large bore IV and treat for shock

*

* Needle Chest Decompression

Indications Tension Pneumothorax with any two: Respiratory Distress & Cyanosis Decreasing Level of Consciousness Loss of Radial Pulse (hypovolemia) Required Materials 12 to 14 gauge I.V. needle w/catheter 5 cm long Betadine or Alcohol Prep Pads Surgical Gloves (2 pair) Tape

* Identify the following anatomical landmarks on the side of the tension pneumothorax Mid-clavicular line Second intercostal space - superior edge of the 3rd rib


Needle Chest Decompression

*

Steps for performing the procedure Position of Casualty: this procedure is not dependant on any single position that the casualty may be in or able to be moved to. Casualty may be lying flat, sitting etc.

*

Site preparation: accomplished using either alcohol and or betadine prep pads to disinfect the skin Using your index finger trace the mid- clavicular line, then identify the second intercostal space (between the second and third ribs) on the side of the tension pneumothorax

*

Steps for performing the procedur; Insert the needle perpendicular to the chest wall, directly over the top of the third rib until a palpable pop is felt followed immediately by a hissing of air escaping from the chest cavity A rush of air confirms the diagnosis and rapidly improves the patient's condition

*

* Complications

Laceration of the intercostal vessels or nerve may cause hemorrhage or nerve damage Creation of a pneumothorax may occur if not already present Infection is a possibility

Chest tube insertion

Most common intervention Relatively simple procedure Definitively manage > 85% of chest trauma : penetrating or blunt
Has significant complication rate (2-19%). May be minor but May require operative intervention and Can result in death

Chest tube

Drain contents of pleural space air blood chyle gastric contents
Prevent development of pleural collection i.e. after thoracotomy Prevent tension pneumothorax in ventilated pt with rib fractures

Chest tube insertion Indications:-

Absolute indications Pneumothorax. Hemothorax.
Relative indications Rib fractures and positive pressure ventilation. Profound hypoxia/hypotension with penetrating chest injury.

Placement may be Diagnostic or Therapeutic

Bright red blood suggest arterial injury = possible thoracotomy Intestinal contents esophageal, stomach, diaphragm intestinal injury Large air leak - bronchial disruption Technique = important to avoid complications

Chest tube insertion Insertion Site

mid or anterior axillary line behind pectoralis major above 5th rib since on expiration diaphragm rises that high count down from sternomanubrial joint (2nd rib)

Chest tube insertion Analgesia

Painful especially in muscular pts Morpine IV or Ketamine 20mg in adult 10-20 ml local analgesia along line of incision perpendicularly thru all layers of chest wall to rib below space up into pleural cavity after aspirating air

Chest tube insertion Procedure

Prep and drapeIncise along upper border of the rib below the intercostal space to be usedTrack is to be directed over top of lower rib so as to avoid intercostal vessels lying below each rib should be big enough to fit fingerUse curved clamp to develop tract by blunt dissection only – use to spread the muscle fibers, develop tract with fingersOn reaching rib, clamp angled upward just above the rib and dissection continued till pleural space entered

Chest tube insertion Procedure

Finger inserted into pleural space and area palpated 32-36 F tube attached to clamp and inserted along track into the pleural cavity

Chest tube insertion Procedure

Connect tube to underwater seal and suture in place Examine chest to check effect CXR to check placement and position

POSITION - Dependent on direction of tract

Blunt chest trauma pts lying flat place drain anteriorly prevents blockage of tube and development of tension pneumothorax
Penetrating Posteriorly & basally directed drain Last hole should be INSIDE the CHEST CAVITY If too far in could cause severe intractable pain when up against mediastinum

Chest tube insertion Underwater Seal

Allows air to ESCAPE but NOT RE-ENTER chest cavity Negative pressure dependent upon level of water Pleurovac must always be below level of patient Persistent bubbling = air leak from lung

Chest tube insertion Underwater Seal

May be connected to suction (water level 20cm H2O) Aid lung re-expansion especially if there is an air leak
CHEST TUBES SHOULD NEVER BE CLAMPED = TENSION PNEUMOTHORAX

Chest Tube Removal

When? When no air leak No more fluid draining
How? Occlude hole while pulling tube. Remove at end of expiration or at peak of inspiration. Avoids air being drawn into cavity. Remove rapidly and close wound quickly.

Chest tube insertion Complications

“there is no organ in the thoracic or abdominal cavity that has not been pierced by a chest drain”mainly historical since drains used to be inserted with- a steel trocar - excessive force

Chest tube insertion Acute complications

Hemothorax – usually laceration of intercostals vessel, may require thoracotomyLung laceration especially when adhesions presentDiaphragm / abdominal cavity penetration - placed too lowStomach colon injury - diaphragmatic hernia not recognized Tube placedsubcutaneously – not inpleural cavityTube placed too far = painTube falls out = not secured properly

Chest tube insertion Late complications

blocked tube = clot, lung retained hemothorax empyema pneumothorax after removal = poor technique

Chest trauma summary

Common Serious Primary goal is to provide oxygen to vital organs Remember Airway Breathing Circulation Be alert to change in clinical condition Managed MOST of the time with a CHEST TUBE

CHEST TRAUMA

END

Pulmonary Hydatid Cysts

Pulmonary Hydatid Cysts


Echinococcosis or hydatid disease is caused by larvae of the tapeworm Echinococcus. Four species are recognised in humans and the vast majority of infestations are caused by E. granulosus. Humans are exposed less frequently to E. multilocularis, which causes alveolar echinococcosis. E. vogeli and E. oligarthrus are rare species and cause polycystic echinococcosis.


The E. granulosus requires two hosts to complete its life cycle. Dogs are the definitive host and a variety of species (sheep, cattle, horses, pigs, camels and humans) are the intermediate host. Humans are accidental hosts and are usually infected by handling an infected dog. and do not play a role in the biological cycle. The liver and lungs are the most frequently involved organs. Pulmonary disease appears to be more common in younger individuals.

Epidemiology

Public health problems are encountered in endemic areas, such as South America, the Middle East, Africa, Russia, China, Australia and New Zealand.

Parasite Biology

The fully developed cysts are composed of three layers. The outer layer, or pericyst, is composed of inflamed fibrous tissue derived from the host. The exocyst is an acellular laminated membrane. The innermost layer, or endocyst, is the germinative layer of the parasite and gives rise to brood capsules (secondary cysts), which bud internally. An intact cyst, if large, may be filled with litres of fluid. The fluid, which is antigenic and may contain debris, contains hooklets and scolices and is referred to as hydatid sand. It has characteristic radiographic and sonographic features . Daughter cysts may develop directly from the endocyst, resulting in multicystic structure.


Organ involvement Following ingestion of E. granulosus eggs, the cyst can be found in virtually any organ (primary echinococcosis).Secondary echinococcosis results from the spread of the hydatid cyst from the primary sites. Patients with cystic echinococcus, 85–90% show single organ involvement and 70% harbour a solitary cyst. The liver is the most common site of cyst formation, followed by the lung in 10–30% of cases and other sites (usually the spleen, kidney).


Pathogenesis:
ingestion of the parasite eggs ,contain embryos (oncospheres) which penetrate the intestinal mucosa and enter the blood and lymphatic system, movement to visceral organs

Clinical features

The initial infection is asymptomatic and remain for many years.Seen at any age and sex, more common 20–40 yrs.Most cysts are discovered incidentally on chest radiographs.Unruptured cyst results in cough, haemoptysis or chest pain .Small cysts remain asymptomatic indefinitely, but enlarge cyst to 20 cm in diameter cause symptoms by compressing adjacent structures.

The cyst may rupture spontaneously or as a result of trauma or secondary infection. Rupture may be associated with the sudden onset of cough and fever. If the contents of the cyst are expelled into the airway, expectoration of a clear salty tasting fluid containing fragments of hydatid membrane and scolices may occur. Symptoms result from the release of cyst antigenic material and immunological reactions that develop , Fever and acute hypersensitivity reactions ranging from urticaria and wheezing to life-threatening anaphylaxis may be the principal manifestations.

Diagnostic work-up:

Plain chest radiograph ( CXR) Typical chest radiographic appearances pulmonary hydatid disease are one or more homogeneous round or oval masses with smooth borders surrounded by normal lung tissue . If the ruptured cyst When it has completely collapsed, the endocyst floats freely in the cyst fluid (water-lily sign). Computerised tomography (CT). (MRI). Ultrasound: screening abdominal cysts, follow-up after treatment

CXR

CT SCAN

CT SCAN


MRI



Laboratory eosinophilia : less than 15% of cases exhibit. Serology: An enzyme-linked immunosorbent assay or indirect haemagglutination test. Histopathological examination: visualisation of cyst wall with scolices or remnants( hooklets) using Ziehl-Neelsen stain.

Management

Surgical treatment. For patients who are able to undergo surgery, it is considered the treatment of choice since the parasite can be completely removed and the patient cured, cure rate: 90%. Pre-surgery: medical treatment with albendazole: recommended, at dose of 10-15 mg/kg per day in two gifts. (at least four days before surgery and to continue for at least one to three months). The surgical options for lung cysts include lobectomy, wedge resection, pericystectomy.

Scolicidal agents such as hypertonic saline, cetrimide, povidone-iodine, formalin, ethanol or hydrogen peroxide may be used, it must remain in contact with the cyst for o15 min. Most surgeons use 1% formaldehyde or hypertonic saline solution for deactivation of cysts and protection of the operative field.


Medical treatment.Therapy is usually indicated for 3–6 months.Albendazole , Mebendazole, Praziquantel.Albendazole is preferred because it has better bioavailability.Albendazole is given at a dosage of 10– 15 mg\ kg body weight\ day in two divided doses and the usual dose is 800 mg daily.Drugs only: patients with inoperable disease, multiple cysts (2 or more organs), after incomplete surgery or relapse, for prevention of secondary spread following rupture and where surgery facilities are not available.

Prevention

Avoiding close contact with dogs. Careful washing of fresh produce can also reduce infection. Vaccination is also a prospect for prevention of echinococcosis, since protective immunity develops in intermediate hosts





رفعت المحاضرة من قبل: Abdalmalik Abdullateef
المشاهدات: لقد قام 29 عضواً و 303 زائراً بقراءة هذه المحاضرة








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