DISCUSSION:
Children with BMT and bilateral pulmonary infiltrates pose a particular challenge. As mentioned previously, they have a very high mortality risk including a 50% mortality with up to 80% of total mortality post BMT coming from pulmonary complications. If intubation and ventilation is required mortality may approach 95%.
Snyderiii et al, in1990, published a case series of 94 OLB's in 87 patients post BMT. 54 (60%) had definitive diagnosis made (CMV in 9 and Aperigillus in 5 being most common). A clinical improvement after a change in antimicrobial coverage was reported in 18%. However there remained a 75% overall mortality.
Wangiv et al, in 2004, published a series open lung biopsies from a cohort of 341 patients with BMT in Taiwan. 68 of the 341 patients developed diffuse pulmonary infiltrates and 35 underwent OLB. The OLB's were done "early" after initial investigations were negative or "late" if there was no response to 3 days of empirical treatment. An infectious etiology was identified in 12 (CMV pneumonitis in 7) and a non-infectious etiology was identified in 23 (interstitial pneumonitis 14). A therapeutic change was reported in 22 (63%) with a clinical response in 16 patients. There was an overall mortality of 50% in the 68 patients with a mortality of 37% in patients who underwent OLB. However the authors comment that OLB's were not performed in the more unstable patients. If the patient had respiratory failure, the mortality was 75%.
Hayes-Jordanv et al, in 2002, published a series of 19 patients post BMT (15 allogenic). 17 of 19 OLB's led to treatment changes. There was an initial clinical improvement in 8 patients (43%) and sustained clinical improvement (survival) remained in 3 patients (16%). 6 patients had an infectious etiology (Aspergillus in 4). Of note, all 11 patients who required ventilation did not survive. This included 3 who were ventilated before OLB and 8 who required prolonged intubation (over 48 hours) post OLB.
The question which arises from these series is whether an earlier OLB increases the benefit. In Wang's series, where biopsies appear to have been performed earlier, there appears to be a higher clinical benefit from OLB than the other 2 studies. However this may be just due to patient selection as much as biopsy timing as the authors themselves note that the more stable patients tended to be selected for OLB's. A concern may be raised regarding complications in Hayes-Jordan's series in which 8 patients, who were not intubated prior to the OLB, were subsequently not extubated and died. However this may have been due to the disease process and timing of the OLB as the children may have been clinically deteriorating and may have required intubation in any case and in fact an earlier biopsy may have been beneficial.
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