Colloid osmotic pressure and pulmonary edema

Changes in colloid oncotic pressure during and after cardiopulmonary bypass

Thirty-one patients undergoing open-heart surgery for uncomplicated coronary artery disease were studied. All patients had dextran 70 (Macrodex, Pharmacia) in the priming solution. In Group I patients (n = 16) 3.5% dextran 40 (Rheomacrodex, Pharmacia) was added to the cardioplegic solution. Group II patients (n = 15) received our standard crystalloid cardioplegia. A higher colloid oncotic pressure (COP) was noticed in Group I during cardiopulmonary bypass (CPB) and immediately postoperatively. The albumin levels were higher in Group II during and after bypass. No differences could be demonstrated in the concentrations of total serum protein. Preoperative levels of COP were reached two hours postoperatively and 24 hours postoperatively for albumin and total proteins. The addition of dextran 40 to the cardioplegic solution did not influence haemodynamic parameters. The clinical course was uneventful in both groups.

The lung permeability index: a feasible measurement of pulmonary capillary permeability

BACKGROUND

We performed this study to determine the pulmonary capillary permeability (PCP) measuring radiolabeled human serum albumin leakage into the lung. The objective was to use PCP to differentiate between cardiogenic and non-cardiogenic pulmonary edema etiologies.

METHODS

We conducted this study in 10 patients admitted to the intensive care unit who had recently developed bilateral pulmonary infiltrates and required hemodynamic monitoring. In these patients we determined the association among the lung permeability index, cardiac output, pulmonary capillary wedge pressure, myocardial performance index, and the protein content of the bronchoalveolar lavage as expressed by bronchoalveolar lavage (BAL) total protein and BAL-to-serum protein ratio. Twenty mCi of technetium-labeled albumin was injected and measure in the heart and the lung at 10 and 180 min post-injection. Lung and heart uptake ratios as well as the lung permeability index were calculated.

RESULTS

We found a good correlation between the lung permeability index and both the myocardial performance index (cardiac output/pulmonary capillary wedge pressure) and the total protein content of the bronchoalveolar lavage fluid.

CONCLUSION

The lung permeability index is a feasible, noninvasive estimation of the pulmonary capillary permeability.

Cardiovascular alterations in severe pregnancy-induced hypertension: relationship of central venous pressure to pulmonary capillary wedge pressure

The relationship between central venous pressure and pulmonary capillary wedge pressure was studied in 18 patients with severe pregnancy-induced hypertension. Although statistically a linear relationship for the group as a whole could be identified, analysis on a case-by-case basis revealed different results. In 10 patients, a linear correlation between central venous pressure and pulmonary capillary wedge pressure was observed. However, accurate prediction of pulmonary capillary wedge pressure from central venous pressure was not possible even in this group because of large interindividual variations. In seven patients no correlation between central venous pressure and pulmonary capillary wedge pressure could be identified. In the last patient a curvilinear relationship existed between central venous pressure and pulmonary capillary wedge pressure. Additionally, in five cases of pulmonary edema, a negative gradient of colloid osmotic pressure to pulmonary capillary wedge pressure gradient was observed. Our data suggest that central venous pressure is not a clinically reliable predictor of pulmonary capillary wedge pressure.

Intrapartum to postpartum changes in colloid osmotic pressure

A study was undertaken to determine the effect of route of delivery on plasma colloid osmotic pressure. Plasma colloid osmotic pressure was measured on admission to the hospital and 8 to 24 hours post partum in 72 patients at term with uncomplicated prenatal histories. Thirty-six patients underwent uncomplicated vaginal deliveries (local anesthesia, 18; conduction anesthesia, 18) and 36 patients had cesarean sections (conduction anesthesia, 18; general anesthesia, 18). The mean (+/- SD) intrapartum colloid osmotic pressure of the overall group was 21.0 +/- 2.1 mm Hg, and it declined significantly (p less than 0.01) to 15.4 +/- 2.1 mm Hg post partum. A comparison of the intrapartum and postpartum reductions in colloid osmotic pressure between patients who underwent vaginal delivery and those who underwent cesarean section revealed no significant differences. Furthermore, the mean reductions in colloid osmotic pressure when all four groups were compared by type of anesthesia were not significantly different. Fifteen patients (20.8%) in the study had a postpartum colloid osmotic pressure of less than 13.6 mm Hg, and five (6.9%) had a postpartum colloid pressure of less than 12.5 mm Hg. Our results indicate that, for normal pregnancy, colloid osmotic pressure is uniformly lowered in the post partum and, in some cases, to levels that have been reported to be dangerously low.

Acute circulatory failure

Sophisticated techniques for invasive and noninvasive monitoring of the cardiovascular, respiratory and metabolic consequences of shock, together with application to therapy of nutritional implications of disordered substrate metabolism that preferentially consumes vital protein stores, will result in further reduction of mortality, particularly in septic shock. Early recognition of the responsible hemodynamic abnormality and its underlying cause, followed by monitored fluid challenge and the selective rather than routine use of vasoactive drugs, is the basis of current shock therapy. As more is learned of the profound catabolic and related hyperdynamic abnormalities of severe sepsis, it is apparent that therapy will be redirected toward provision of energy substrates and altering hormonal patterns to favor anabolism.