ARDS is defined as the acute onset of respiratory failure with refractory hypoxaemia (arterial oxygen tension (Pao2)/ inspiratory oxygen fraction (Fio2) ratio <200 mm Hg) and bilateral infiltrates on frontal chest radiography that cannot be explained by, but may co-exist with, increased left atrial pressure (occluded pulmonary artery pressure (Ppa) <18 mm Hg).68 ARDS is the extreme manifestation of a spectrum of acute lung injury (ALI) defined identically except for the presence of less severe refractory hypoxaemia (Pao2/Fio2 <300 mm Hg). The extent to which lung resection fulfils this requirement remains controversial as pneumonectomy, by definition, precludes the development of bilateral pulmonary infiltrates. However, most authorities now accept that many patients with what has been termed "post-pneumonectomy pulmonary oedema (PPO)" display the physiological and radiological defining criteria for ALI/ARDS.69
The reported mortality rate for ALI/ARDS associated with thoracotomy and pulmonary resection varies from 2% to 12%.70 71 ALI/ARDS is the commonest cause of death following pulmonary resection,72 73 and the majority die as a result of multiple organ failure.74 The mortality rate remains high despite advances in supportive techniques. Before a consensus definition of ALI/ARDS was agreed, the incidence was reported to vary from 4% to 7% following pneumonectomy and from 1% to 7% after lobectomy, with an associated mortality of 50-100%.75-77 A retrospective study using the consensus definition68 found an incidence of 2.2%/5.2% for ALI/ARDS following lobectomy and 1.9%/4.9% after pneumonectomy.78 A further study showed an incidence of 6%, 3.7%, and 1% for ALI/ARDS following pneumonectomy, lobectomy, and minor resections, respectively.73 In this latter study ALI/ARDS contributed to 72% of all postoperative deaths.
No correlation has been found between age, preoperative lung function, arterial blood gas analysis, or duration of
surgery and the development of ALI/ARDS.72 78 However, men over the age of 60 years, especially when undergoing lung resection for lung cancer, form a high risk group.73 Furthermore, no correlation has been found between the side of resection and the development of ALI/ARDS, but the risk increases progressively with more extensive resections.73 75 79 ALI may present up to 7 days after surgery,73 77 but most patients present between 1 and 3 days postoperatively.75 76 Excessive perioperative administration of crystalloid may precipitate respiratory failure,74 77 although recently the perceived role of fluid overload has diminished.75 76 The high protein content of the alveolar oedema fluid and the frequent delay in presentation suggest that perioperative fluid overload is not the primary cause of post-pulmonary resection lung injury. The differential diagnosis includes lower respiratory tract infection and cardiogenic pulmonary oedema (fig 15.3]). Both can be investigated in the intubated patient by tracheal aspiration or bronchoscope guided sampling and pulmonary arterial catheterisation.
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Among the evils which a vitiated appetite has fastened upon mankind, those that arise from the use of Tobacco hold a prominent place, and call loudly for reform. We pity the poor Chinese, who stupifies body and mind with opium, and the wretched Hindoo, who is under a similar slavery to his favorite plant, the Betel but we present the humiliating spectacle of an enlightened and christian nation, wasting annually more than twenty-five millions of dollars, and destroying the health and the lives of thousands, by a practice not at all less degrading than that of the Chinese or Hindoo.