Pulmonary microembolisation as a result of trauma, sepsis or major surgery may be an aetiology for shock lung. The postoperative kinetics of 111-Indium labeled autologous platelets have been studied to determine whether they accumulate in the lungs, and whether this relates to subsequent pulmonary function.One day prior to major surgery platelets from 10 patients were labelled with 111-Indium-oxine and reinjected. Isotope emissions were counted over the lungs and aortic arch preoperatively, 2.5

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... hours following surgery and daily for 7 days. Screen filtration pressure (SFP) measurements of aggregates in femoral vein blood was estimated 30 minutes and 3 hours postoperation. Arterial PO2 was measured preoperation and on days 1 and 7 following surgery.The ratio of isotope emissions lung/aortic arch increased following surgery indicating pulmonary accumulation of platelets. The preoperative ratio (mean ± SEM) of 0.38 ± 0.017 rose to 0.47 ± 0.039 (p<0.05) 2.5 hours following surgery and to 0.56 ± 0.052 (p<0.01) the following day. This ratio had returned to preoperative levels by day 4. Immediate postoperative platelet accumulation in the lung (the rise in lung/ aortic arch ratio) correlated closely with SFP measurements (r 0.89, p<0.01) and the fall in arterial PO2 one week following surgery (r 0.69, p<0.05).These results indicate that circulating platelets aggregate during surgical shock and then accumulate in the lungs. This process is associated with postoperative hypoxia.