Brain abscesses associated with pulmonary arteriovenous malformations.

We present three patients with brain abscesses who also had pulmonary arteriovenous malformations (AVMs). All patients had hereditary haemorrhagic telangiectasia (Osler's Disease). It is probable that the lung AVMs contributed to the development of the brain abscesses by allowing bacteria easier access to the systemic circulation through a right to left pulmonary vascular shunt, bypassing the filtering action of the pulmonary capillaries. In addition, one patient required a period of postoperative ventilation using PEEP, which may have exacerbated the shunt through the lung AVM and led to difficulty in weaning her from the ventilator.