20.5.pleural effusion &empyema

PLEURAL EFFUSION &EMPYEMA

Dr.BANUPRIYA

The pleural space lies between the lung and chest wall and normally contains a thin layer of fluid.

Pleural effusion is present when there is an excess quantity of fluid in pleural space.

MECHANICS OF PLEURAL EFFUSION

Increased capillary/pleural membrane permeabiltiy

Increased capillary hydrostatic pressure Decreased intravascular oncotic pressure Lymphatic obstruction Abnormal sites of entry

TRANSUDATIVE EFFUSION –results from alteration in hydrostatic or oncotic pressure of capillaries in parietal pleura

EXUDATIVE EFFUSION- results from change in permeability of capillaries or pleural membranes or from obstruction in lymphatic drainage.

Transudative effusion Nephrotic syndrome Congestive cardiac

failure Hepatic failure PEM Hypothyroidism

Exudative effusion Infections-Pneumonia,lung

abcess,bronchiectasis,TB Malignancy-

Metastasis,leukemia/lymphoma

Collagen vascular diseases-SLE,JRA

Traumatic Drugs-

Amiodarone,bromocriptine Postradiation

Light’s criteria Exudative effusion meet atleast one of the following

criteria,wheras transudative effusions meet none. Pleural fluid protein/serum protein > 0.5 Pleural fluid LDH/serum LDH > 0.6 Pleural fluid LDH-more than two third of serum LDH The above criteria misidentify 25% of transudatesas exudates.

CLINICAL FEATURES

Symptoms depend on the underlying cause of pleural effusion

Commonly presents with pleuritic chest pain(sharp stabbing pain worsened by deep inspiration),dyspnoea,cough

On examination Tachypnea,chest retractions Decreased chest movements on the affected side (hoover’s

sign) Tracheal and mediastinal shift in large effusions

Decreased vocal fremitus and vocal resonance Decreased or absent breath sounds Bronchophony or aegophony above the level of effusion. Dullness on Traube space percussion

CHYLOTHORAX Accumulation of chyle in pleural space. Common causes are -Trauma to thoracic duct -Tumor -Lymphatic obstruction

Pleural fluid characteristics-milky white,high triglyceride levels

Hemothorax Presence of blood in pleural space. Common causes are - Chest wall injuries - Malignancy - Bleeding disorders - Pulmonary infarction

Parapneumonic effusion&empyema

Parapneumonic effusion – sterile pleural effusion with few or no inflammatory cells.It occurs in around 40% of bacterial pneumonias.

Empyema –presence of pus or microorganism in pleural fluid.

Common causative organisms – Staphylococcus aureus,streptococcus pneumoniae,Hemophilus influenza, streptococcus pyogenes

Gram negative organisms and MRSA are more common pathogens in HIV associated empyema.

Anaerobic organisms like bacteroides are common in empyemas following aspiration pneumonia

Atypical organisms like mycoplasma,Chlamydia, viruses,fungi like candida,aspergillus rarely cause empyema.

Although tuberculous effusions are relatively common,tuberculous empyema is quite rare.

PATHOGENESISIt occurs in three stagesExudative stage Clear sterile fluid accumulates in pleural space as a result of

increased pleural and capillary permeability associated with infection

Fibrinopurulent stage Bacterial invasion of pleural space Deposition of fibrin in pleural space leading to septation or

loculations Characterised by presence of turbid fluid or frank pus

Organisational stage ( >14days) Infiltration of fibroblasts in pleural space Thin fibrin membranes transformed into thick pleural

peels,resulting in ‘trapped lung’. More common in staphylococcal empyema Complications like chronic empyema,bronchopleural fistula

and spontaneous perforation through chest wall (empyema necessitans)

Clinical features

Presents with high grade fever with chills,malaise,dyspnoea, pleuritic chest pain.Child prefers to lie on affected side splinting the chest with knees drawn up to the chest.

On examination,in addition to usual findings of pleural effusion,erythema,edema and tenderness of chest wall on affected side may be noted.

INVESTIGATIONS

Chest xray An anteroposterior chestxray should be done in all

children with suspected pleural effusion. Atleast 300ml of fluid should be present to detect effusion clinically and radiographically in AP view.

Lateral decubitus CXR with affected side inferior allows recognition of smaller volumes of fluid.

Xray features- Obliteration of costophrenic and cardiophrenic angles

homogenous opacity of affected hemithorax with mediastinal shift to contralateral side

Ultrasound Helps to differentiate consolidated lung from pleural fluid

especially when there is white out on CXR and clinical signs do not clearly distinguish

Identify pleural thickening and loculated effusions To guide thoracocentesis and chest tube insertion

CT thorax Useful if effusion is minimal or loculated to differentiate effusion from pleural thickness

Thoracocentesis(pleural tap) Indicated if pleural fluid thickness from chest wall more

than 1 cm in lateral decubitus xray and that is of uncertain etiology

Pleural fluid analysis- Gross examination Cell count pH Glucose LDH Protein Gram stain and culture

Lymphocytois-suggestive of tuberculous effusion or malignancy

Pleural fluid ADA > 70IU/L is suggestive of tuberculous effusion.

Biochemical analysis of pleural fluid is unnecessary in case of frank pus.

Blood culture Positive in 10-20% of cases of empyema Sputum,tracheal aspirate and bronchoalveolar lavage sent for

cultures if possible in parapneumonic effusions

Investigations relevant to underlying cause

TREATMENT

• Treatment of underlying cause

• Parapneumonic effusions - appropriate antibiotic therapy and supportive treatment

Simple drainage in case of large effusions and compromised pulmonary function

• Empyema –Antibiotic therapy,supportive treatment and chest tube drainage.

Supportive treatment Adequate oxygenation to maintain spO2>92% Nutrition and adequate hydration

Antibiotic therapy Commonly used antibiotic combinations are cloxacillin and

amikacin Cloxacillin and third generation cephalosporins

In immunocompromised children,cloxacillin and ceftazidime started to cover pseudomonas and other gram negative anaerobes.

If response is poor ,if multiple loculations or putrid smelling pus present,antibiotics for anaerobic cover like clindamycin or metronidazole added.

If MRSA suspected,vancomycin is added.

Treatment is modified based on culture and sensitivity reports.

Parenteral therapy should be continued for 48-72 hrs after abatement of fever and then oral therapy can be used to complete the course.

Antibiotics should be continued till the patient is afebrile and,chest tube drainage is less than 50ml/day.

Duration of antibiotics- 7-14days in case of s.pneumonia or h.influenza

3-4weeks in case of s.aureus

Chest tube drainage Chest drain should be inserted in all children diagnosed

with empyema.Repeated taps are not recommended.

Preferred site for insertion- preferentially in midaxillary line through safe triangle or as suggested by ultrasound

Tube is connected to underwater seal drainage.

Chest drain should be removed if fluid drainage is less than 30ml/day and no residual air or fluid collection noted.

Exercises Early ambulation and breathing exercises are advised to

improve lung expansion ,once toxemia subsides. Chest physiotherapy is not beneficial and not recommended

in children.

Intrapleural fibrinolytic therapy

Instillation of fibrinolytic agents in pleural space via chest drain lyses fibrin strands and clears lymphatic pores ,thus facilitating better drainage.

Agents used – urokinase-proven safe and effective in children

Streptokinase Alteplase

Surgery Considered when empyema fails to resolve despite above

mentioned treatment or in cases of organized empyema(trapped lung)

bronchopleural fistula Options – minithoracotomy and debridement Open decortication Video assisted thoracoscopic adhesiolysis

(VATS)

Complications of empyema Pyopneumothorax Bronchopleural fistula Empyema necessitns Septicemia

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