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By means of a volumetric respirometer, oxygen consumption and carbon dioxide production were measured in 15 patients with chest trauma who required mechanical ventilation. From the primary measurements, respiratory quotient, daily energy balance, and cumulative energy balance were calculated. There was a moderate increase in metabolic rate, which generally returned to normal during the first week after trauma. A late increase in oxygen consumption was associated with sepsis, large energy deficit, and death in three patients. Carbon dioxide overload caused by excessive feeding caused difficulty in weaning three patients from the ventilator. Measurement of oxygen consumption and carbon dioxide production is helpful in the management of patients with chest trauma and respiratory failure.

Hyperacute rejection (HAR) currently precludes the use of discordant organs for human transplantation. In order to comprehensively evaluate HAR in a clinically applicable species combination, we have developed an ex vivo perfusion model utilizing a neonatal extracorporeal membrane oxygenator circuit; this model allows for functional and sequential biopsy studies of working piglet hearts sustained by human, single donor AB+type blood. A detailed description of the methods employed is included. Hearts perfused by allogeneic pig blood sustained normal function throughout the study period, while those perfused with human blood lost organized ventricular contraction in 25–34 min with markedly attenuated function. Compared with biopsies from piglet hearts perfused with allogeneic blood and biopsies taken prior to human blood perfusion (t=0), biopsies of hearts perfused with human blood at t=15 and 30 min demonstrated significant inflammatory changes involving vessels (endothelial and myointimal swelling and reaction) as well as myocardium (injury and necrosis). By immunohistology, significant vascular deposition of IgM, IgG, fibrinogen, C3, and C1q was seen, along with infiltrates of human leukocytes consisting predominantly of neutrophils, macrophages, and T cells, with occasional B cells and NK cells. Sequential studies of circulating blood demonstrated the progressive consumption of human leukocytes and human anti-porcine antibodies, but no decrease in complement activity as measured by CH50. These findings indicate that the rapid loss of function seen in human anti-porcine cardiac HAR is associated with deposition of IgM and IgG xenoreactive antibody and early complement components and that extensive infiltration by inflammatory cells occurs within 15–30 min. This model provides a useful system for the study of human anti-porcine HAR.