Transbronchial TBB versus surgical lung SLB biopsy

TBB carries a substantial risk of pneumothorax which afflicts 8-14% of ventilated patients.1415 For this reason, TBB is rarely performed in these circumstances except in patients after lung transplantation where the sensitivity for detection of acute or chronic rejection is 70-90%, with a specificity of 90-100% when performed in an appropriate clinical context.16-18 The Lung Rejection Study Group recommends collecting at least

Figure 1.2 Radiology of a case of haemodynamic pulmonary oedema and histological non-specific interstitial pneumonia masquerading as community-acquired pneumonia and ARDS. Prominent septal lines (upper panel) and large pleural effusions (lower panel) suggest a cardiac cause of pulmonary oedema in this man aged 30 years of no fixed abode. Having failed to respond to antibiotics and corticosteroids, he improved following two vessel coronary angioplasty, mitral valve replacement with one coronary artery bypass graft, and finally a further course of high dose steroids. The diagnosis of ischaemic mitral valve regurgitation was made by stress echocardiography. Subsequently, pulmonary diagnosis was made by an open lung biopsy taken at the time of his cardiac surgery.

Figure 1.2 Radiology of a case of haemodynamic pulmonary oedema and histological non-specific interstitial pneumonia masquerading as community-acquired pneumonia and ARDS. Prominent septal lines (upper panel) and large pleural effusions (lower panel) suggest a cardiac cause of pulmonary oedema in this man aged 30 years of no fixed abode. Having failed to respond to antibiotics and corticosteroids, he improved following two vessel coronary angioplasty, mitral valve replacement with one coronary artery bypass graft, and finally a further course of high dose steroids. The diagnosis of ischaemic mitral valve regurgitation was made by stress echocardiography. Subsequently, pulmonary diagnosis was made by an open lung biopsy taken at the time of his cardiac surgery.

Table 1.2

Typical bronchoalveolar lavage differential cell counts

in conditions associated with acute respiratory failure

and diffuse pulmonary infiltrates

Condition

Cell differential counts

Comments

Macrophage Lymphocyte Neutrophil Eosinophil

Normal

90% 10% <4% <1%

Neutrophils usually <2% in non-smokers

Acute interstitia

t t t

Eosinophils or neutrophils each raised in about 70% of cases of

pneumonia

CFA; both being raised is characteristic. Neutrophils may be

raised in isolation but this is more typical of infection. Lymphocytes

raised in about 10%

Alveolar

t

BAL fluid may be bloody. Haemosiderin-laden macrophages

haemorrhage

t

appear after 48 hours and are diagnostic

ARDS

Neutrophils commonly around 70% of differential count

Bacterial

t

Neutrophils >50% in ventilated patients with bacterial pneumonia

pneumonia

tt

Eosinophilic

Eosinophils typically 40%, range 20-90%. Neutrophils may also

pneumonia

be raised, but always lower than eosinophils

CFA = cryptogenic fibrosing alveolitis; BAL = bronchoalveolar lavage; ARDS = acute respiratory distress syndrome.

five pieces of lung parenchyma to get an adequate sample of small bronchioles and to diagnose bronchiolitis obliterans.19 Widespread pulmonary infiltrates developing within 72 hours of lung transplantation are more likely to represent alveolar oedema caused by ischaemia-reperfusion injury than rejection or infection.20 21

A recent study retrospectively examined the strategy of performing BAL and TBB simultaneously rather than as staged procedures in mechanically ventilated patients with unexplained pulmonary infiltrates.22 Pneumothorax occurred in nine out of 38 patients, six requiring intercostal tube drainage; four out of 38 suffered significant bleeding that was self limiting or terminated with instillation of adrenaline. Diagnostic yields were estimated at 74% for BAL/TBB, whereas those for TBB and BAL alone were 63% and 29%, respectively. Patients in the later phases of ARDS represented 11 of 38 patients and experienced a relatively high incidence of complications and lower diagnostic value, in part because BAL alone could adequately diagnose infection.

A 10 year retrospective review of 24 mechanically ventilated patients undergoing SLB found that a diagnosis was made histologically in 46%.23 Intraoperative complications were generally well tolerated, although 17% had persistent air leaks and two patients died as a consequence of the procedure. Complication rates in other series have been lower and the estimates of diagnostic usefulness have been considerably higher.24-27 For example, in 27 patients with ARF, persistent air leak occurred in six following SLB but there were no perioperative deaths.27 In a retrospective review of 27 OLBs in patients with ARF, persistent air leak occurred in six but there were no perioperative deaths.27 In a retrospective series of 80 patients,26 many of whom were immunosuppressed, eight had a persistent air leak with one perioperative myocardial infarction.

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