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This study assessed the reliability of 131I albumin-dilution for measuring induced changes in plasma volume (PV) immediately after coronary bypass surgery. After injection of the tracer, blood samples were collected from 18 control patients to obtain 131I albumin decay curves in the plasma. These curves were used to construct a mathematical model describing tracer decay. PV was then calculated in control patients, and in 51 study patients who received plasma expanders on the first postoperative morning. At 1, 15, 30, and 60 min after volume loading in the study group, dilution volumes were calculated as the difference between predicted and observed plasma radioactivity levels. These calculations were compared to an independent measurement of PV. This method was associated with a measurement error no greater than +/- 12% in 82% of the 51 study patients. It tended to underestimate PV by 2.4%.

Despite increased alveolar ventilation, positive-pressure ventilation (PPV) reproducibly resulted in less efficient arterial oxygenation as compared to diaphragmatic pacing in a quadriplegic patient with respiratory paralysis. Volume loading acutely restored arterial oxygenation during PPV. This report emphasizes the important interaction between the cardiovascular and pulmonary systems in effecting gas exchange, particularly in quadriplegics. In this respect, diaphragmatic pacing seems to perform better than PPV.

The clinical and physiological responses to septicemia were evaluated in 59 patients with 70 septic episodes. All patients were critically ill, had similar ICU support, and had positive blood cultures as well as a clinical infection when studied by dye dilution cardiac outputs. The overall ratio of gram-negative to gram-positive sepsis was 2.6:1.0. Patients with septicemia caused by gram-positive organisms, gram-negative organisms, anaerobes, and fungi had similar fever, leucocyte, and acid-base responses. There were also no statistical differences in any physiological variables between organism group or between specific organisms. After volume loading, all patients exhibited a hyperdynamic cardiovascular response with abnormal vascular tone. Some degree of myocardial depression was a common feature of all forms of bacterial or fungal septicemia. Heart rate was the cardiac variable producing the increased cardiac output in this setting. The exact pathogenesis of the septic response remains undetermined. However, the response appears to be host determined and not peculiar to a specific pathogenic microorganism.

Hemodynamic and oxygen transport measurements were made with successive increments of positive end-expiratory pressure (PEEP) in 14 episodes of ARDS in 11 patients who had normal or slightly increased blood volumes. "Preferred" or optimal PEEP was defined as the PEEP value associated with the greatest VO2 that did not compromise pulmonary function as determined by shunting (Qs/Qt). The preferred PEEP averaged 10.7 +/- 2.7 (SD) cm H2O in the patients who had appreciable reduction in cardiac index (CI) by the time this level of PEEP was reached. In 6 patients, the CI fell approximately 15%; then albumin, 25 g, was given. This restored CI, improved oxygen transport, and permitted us to give additional 10-15 cm H2O of PEEP, i.e., until 20--25 cm H2O was reached; this was achieved without hemodynamic impairment. The final preferred PEEP in these patients averaged 14.1 +/- 3.6 (SD) cm H2O. The authors conclude that the titration of PEEP as well as fluid therapy may be used to maximize VO2 in patients with early shock lung.