[Clinical practice interpretation of oncotic pressure, serum albumin and protein determination and their ability for guiding therapeutics in cases of disturbances of capillary exchanges]

Comparison of whole blood and plasma colloid osmotic pressure in healthy cats

OBJECTIVE

To establish reference intervals for whole blood and plasma colloid osmotic pressure (COP) in healthy cats between the ages of 1 and 10 years using a cage-side colloid osmometer.

DESIGN

Prospective, observational study.

SETTINGS

University veterinary teaching hospital.

ANIMALS

Sixty-three healthy cats.

INTERVENTIONS

Phlebotomy.

MEASUREMENTS AND MAIN RESULTS

Whole blood COP mean was 24.4 (±2.78) mmHg and plasma COP mean was 24.3 (±2.59) mmHg. Reference interval for our study population of feline whole blood COP was 18.9 to 30.4 mmHg, and for our study population of feline plasma COP was 18.3 to 30.8 mmHg. Difference of paired whole blood COP and plasma COP was +0.23 ± 1.68 mmHg (P = 0.32). There was no significant difference when comparing COP from neutered male and neutered female cats. Total protein and albumin were significantly correlated with whole blood COP (total protein to whole blood COP P < 0.0001, r = 0.53; albumin to whole blood COP P <0.0001, r = 0.68) and plasma COP (total protein to plasma COP P = 0.0025, r = 0.41; albumin to plasma COP P < 0.0001, r = 0.66).

CONCLUSIONS

No significant difference was found between mean whole blood and plasma COP in this study population of cats. Even though not statistically significant, evaluation of paired whole blood COP and plasma COP did reveal a slight difference; therefore, it seems prudent to maintain sample consistency for serial evaluations in cats.

Hypoalbuminemia in elderly patients with acute diastolic heart failure

OBJECTIVES

This study evaluated the relative contribution of serum colloid osmotic pressure (COP) lowering and pulmonary artery wedge pressure (PAWP) elevation in the pathogenesis of pulmonary edema in patients with systolic or isolated diastolic heart failure (DHF).

BACKGROUND

The role of hypoalbuminemia and the resulting low COP have been shown in some patients with acute systolic heart failure (SHF). Colloid osmotic pressure and PAWP were determined in 100 patients with acute heart failure (HF) (56 with DHF and 44 with SHF; mean age, 78 +/- 12 years), in 35 patients with acute dyspnea from pulmonary origin, and in 15 normal controls. Pulmonary artery wedge pressure was estimated using transthoracic Doppler echocardiography.

RESULTS

Colloid osmotic pressure was significantly lower in the DHF group (20.5 +/- 5 mm Hg) than in the SHF group (24.2 +/- 3.7 mm Hg, p < 0.001), pulmonary disease group (25.1 +/- 4.2 mm Hg, p < 0.001), or normal control group (24.7 +/- 3 mm Hg). Low COP resulted from hypoalbuminemia due to age, malnutrition, and sepsis. Pulmonary artery wedge pressure was significantly higher in patients with SHF (26 +/- 6.3 mm Hg) than in the patients with DHF (20.3 +/- 7 mm Hg, p < 0.001) and was significantly higher in the patients with DHF than in the patients with pulmonary disease (13 +/- 4.2 mm Hg, p < 0.001). The COP-PAWP gradient was similar in patients with SHF (-1.6 +/- 7.1 mm Hg) and patients with DHF (0.7 +/- 6 mm Hg).

CONCLUSIONS

Frequent hypoalbuminemia resulting in low COP facilitates the onset of pulmonary edema in patients with DHF who usually have lower PAWP than patients with SHF.

[Usefulness in clinical practice of noninvasive measurement of colloids osmotic pressure-capillary pulmonary pressure gradient in the management of acute dyspnea]

BACKGROUND

Increased pulmonary capillary pressure (PAWP) and decreased serum colloid osmotic pressure (COP) are important factors in pulmonary edema (PE) formation. The aim of this study was to evaluate the clinical usefulness of noninvasive determination of COP, PAWP and COP-PAWP gradient in patients with acute dyspnea.

METHODS

Thirty four patients presenting with PE, 19 with preserved left ventricular systolic function (Ia) and 15 with depressed systolic function (Ib), and 26 patients presenting with acute pulmonary diseases (II) were enrolled. COP was estimated using Landis and Pappenheimer formula (COP = 2.1 x P + 0.16 x P2 + 0.009 x P3, P: serum total protein concentration). PAWP was measured by transthoracic Doppler echocardiography using E/Vp and 1000/(2 x IPT + Vp) Doppler indexes.

RESULTS

The mean value of the gradient was 0.5 +/- 5, 1.7 +/- 3.4 and 10.4 +/- 4.7 mmHg in Ia, Ib and II respectively (P < 0.001 Ia and Ib vs II). PAWP was higher in Ia and Ib than in II (P < 0.001). However, hypoalbuminemia with COP < or = 18 mmHg was observed in 63% of patients in Ia as compared to those in Ib (7%) and II (8%).

CONCLUSIONS

Severe hypoalbuminemia frequently contributes to PE formation in the presence of normal left ventricular systolic function. A COP-PAWP gradient value lower than 6 mmHg is highly predictive of the diagnosis of acute heart failure in these patients presenting with acute dyspnea.

Elevated cerebral perfusion pressure and low colloid osmotic pressure as a risk factor for subdural space-occupying hygromas?

BACKGROUND

Space-occupying subdural hygromas are a late complication of severe traumatic brain injury (TBI) and may delay the patient's recovery. To evaluate the risk factors involved, we performed a semiretrospective, -prospective analysis of three groups of patients, which differed with regard to the techniques used in the management of their cerebral perfusion pressure (CPP) and colloid osmotic pressure (COP) to determine the occurrence of space-occupying subdural hygromas.

PATIENTS AND METHODS

Between 1989 and 1997 we examined 696 patients after a severe TBI: Group 1. 1989-1994 mean CPP: 67 (elevated for therapeutic reasons by catecholamines, if necessary), mean COP: 19. Group 2. January 1995-October 1996, mean CPP: 77, mean COP: 20. Group 3. November 1996-December 1997, mean CPP: 79, mean COP: 23 (elevated for therapeutic reasons by infusions of colloids). The groups were comparable for other criteria.

RESULTS

Compared to Group 1, Group 2, with a high CPP but lower COP, showed a significantly higher (p < 0.01; chi2-test with correction of Yates) percentage of posttraumatic subdural hygromas with space-occupying aspects, clinical signs of bradycardia, hypertension and impaired consciousness requiring surgery (Group 1: 1.75%; Group 2: 10.46%; Group 3: 0%). In Group 3 we saw no patient with a space-occupying hygroma.

CONCLUSION

We conclude that iatrogenic elevated CPP, which has been reported to be helpful in preventing secondary ischemic damage after a severe TBI, may be harmful to a patient if the COP is not maintained within physiological ranges.