Decrease In Colloid Osmotic Pressure Research Articles

Pleural Effusions and Pneumothoraces.

1. Katherine Cashen, DO* 2. Tara L. Petersen, MD† 1. *Department of Pediatrics, Children's Hospital of Michigan/Wayne State University School of Medicine, Detroit, MI 2. †Division of Critical Care, Department of Pediatrics, The Children’s Hospital of Wisconsin/The Medical College of Wisconsin, Milwaukee, WI * Abbreviations: BTS: : British Thoracic Society CHF: : congestive heart failure CT: : computed tomography VATS: : video-assisted thoracoscopic surgery 1. Clinicians should be aware of the causes and clinical presentation of pleural effusions and pneumothoraces. 2. Clinicians should understand the current role of diagnostic tests, imaging modalities, and timing of minimally invasive treatments. After completing this article, readers should be able to: 1. Describe the pathogenesis of pleural fluid accumulation. 2. Identify the most likely causes of pleural effusion and pneumothorax. 3. Understand the basic clinical presentation, diagnostic tests, and management of pleural effusions and pneumothoraces. 4. Differentiate between transudative and exudative pleural effusions. 5. Understand the natural history of spontaneous pneumothorax. The pleural space is created by the parietal and visceral pleura that line the chest wall and the lung surface, respectively. Normally, only a small amount (0.3 mL/kg) of hypotonic fluid is present within the pleural space due to homeostatic balances in physiologic fluid production and absorption. Various infectious and noninfectious processes can lead to pathologic filling of the pleural space with fluid (effusion) or air (pneumothorax). Such pathologic changes create a true space that can interfere with normal lung mechanics and, in severe cases, cardiac function. Although much less common in pediatric than adult populations, pleural effusions and pneumothoraces in both groups can lead to substantial complications, resulting in significant morbidity and mortality if unrecognized or untreated. Overall, the cause of pleural effusions and pneumothoraces differs in children compared to adults. In adults, congestive heart failure (CHF) and malignancy account for a substantial number of pleural effusions, but these are uncommon causes in children. Infectious pleural effusions in the setting of pneumonia (parapneumonic effusions) remain the most common cause of effusions in both children and adults. Unlike the adult population, children experience spontaneous …

Perioperative trends in plasma colloid osmotic pressure in horses undergoing surgery.

To compare perioperative trends in plasma colloid osmotic pressure (COP) between horses undergoing orthopedic and colic surgery. Prospective clinical study September 2009-January 2011. Veterinary university teaching hospital. Thirty-three healthy, client-owned horses presenting for orthopedic surgery (non-GI) and 85 client-owned horses presenting for emergency exploratory celiotomy (GI, gastrointestinal). None. Data relating to the horse's parameters on presentation, surgical lesion, post-operative management and survival were extracted from computerized clinical records. Heparinized blood samples were taken on presentation (PreOp, pre-operative), on recovery from anesthesia (T0), at 12 (T12) and 24 (T24) hours post recovery. COP was measured within 4 hours of collection. There was no significant difference in PreOp or T0 COP between groups. Both groups had a significant decrease in COP during anesthesia. When compared to their respective pre-operative values, horses in the non-GI group had significantly increased COP at T12, whereas those in the GI group had significantly reduced COP. This trend was continued at T24. Horses in the GI group placed on intravenous crystalloid isotonic fluids post-operatively had a significantly lower COP at T12 and T24. Horses in the GI group that did not survive had significantly lower post-operative COP values at T24. Horses undergoing exploratory celiotomy had significantly lower COP post-operatively than those horses undergoing orthopedic surgery. This difference was more marked in those horses receiving isotonic crystalloid intravenous fluid therapy post-operatively and in those that did not survive to discharge. In the non-GI group an increase in COP post-operatively was common.

Effects of 10% hydroxyethyl starch (HES 200/0.5) solution in intraoperative fluid therapy management of horses undergoing elective surgical procedures

The aim of the present study was to investigate the effect of pentastarch on colloid osmotic pressure (COP) and cardiopulmonary function during and up to 24 h after anaesthesia in horses. Twenty-five systemically healthy horses were anaesthetised using isoflurane-medetomidine balanced anaesthesia. Twelve were assigned to treatment with hydroxyethyl starch (HES) (H group) and 13 to no HES (NH group). In the H group, 6 mL/kg of pentastarch 10% HES (200/0.5) was infused over 1 h starting 30 min after induction of anaesthesia. Horses of the NH group received an equal amount of lactated Ringer's solution (LRS). COP and blood biochemical, cardiopulmonary and anaesthesia-related variables were measured at different time points before and after treatment.Pentastarch was effective in correcting the decrease in COP observed with LRS administration. No differences between treatments were detected for blood glucose, lactate, total proteins and electrolytes. Packed cell volume was lower with the H group immediately after finishing HES-administration and for an additional 30 min. In all horses, all blood biochemical variables other than lactate returned to normal after 12 h. No clinically relevant differences between treatments were detected for cardiopulmonary variables, although 23.1% of the NH-horses needed rescue-HES to maintain cardiovascular function, while none of the H-horses needed additional colloids. Overall, 6 mL/kg HES (200/0.5) was found to be effective in maintaining COP during anaesthesia in systemically healthy horses. Intermediate and long-term effects were below the limit of detection. The potentially beneficial effects on cardiovascular function need further investigation, especially in critically ill horses.

Sera from early-onset, severely preeclamptic women directly modulate HLA-E expression in the EA.hy296 endothelial cell line

The expression of endothelial HLA-E in the context of the systemic inflammatory response observed in preeclampsia has not been established. An experimental study was designed to determine the effect of the sera of pregnant women on the expression of HLA-E in EA.hy296 endothelial cells. First, measurements of protein fractions were performed in sera from early-onset, severely preeclamptic women without HELLP syndrome, in which there was no significant difference in total proteins between the groups, but a reduced level of plasma albumin and an increase in α1-globulin were observed in both groups of pregnant women compared with non-pregnant women. Measurements of colloid osmotic pressure (COP) using a recalculated albumin/globulin ratio formula determined only a significant decrease in COP in all pregnant groups compared with non-pregnant women. The expression of membrane HLA-E was increased in EA.hy296 endothelial cells stimulated with sera of early-onset, severely preeclamptic women, while recombinant interferon-γ (IFN-γ) significantly reduced the expression of membrane HLA-E. Pro-inflammatory cytokines were measured by Luminex in the serum samples, and increased levels of tumor necrosis factor (TNF) and decreased levels of IFN-γ were observed in early-onset, severe preeclampsia compared with normal pregnancy. Moreover, soluble HLA-E was detected in these serum samples by Western blot and ELISA, but no significant difference was found. This raises the possibility that a systemic inflammatory response promotes a compensatory mechanism of COP balance in severe preeclampsia by release of inflammation-induced factors, including endothelial HLA-E. Evidence is now provided regarding HLA-E expression by EA.hy296 cells.

Concentraciones de Sodio, Potasio y Cloro en líquido Ascitico, Suero y Orina de Pacientes con Enfermedad Hepática

En el presente trabajo se estudian las concentraciones de Sodio, Potasio y Cloro en el líquido ascítico, suero y orina, en ocho pacientes con afecciones Hepáticas de distinta etiología. Las concentraciones de Sodio sérico fluctuaron entre 126.0 y 146.2 mEq/L., el ascítico entre 85.0 y 140.0 mEq/L. y la excreción urinaria fluctuó entre 4.0 y 90.0 mEq/l. en 24 hrs. Las concentraciones de Potasiio oscilaron entre 3.20 y 5.0 mEq/L., el ascítico entre 3.10 y 4.50 mEq/L- y la eliminación urinaria fluctuó entre 8.0 y 56.0 mEq/L. en 24 hrs. El Cloro sérico varió entre 90.0 y 104.0 mEq/L., el ascítico entre 99.0 y 117.0 mEq/L. y la excreción urinaria fue entre 19.0 y 117.0 mEq/L. en 24 hrs. Los niveles extremos de Sodio, Potasio y Cloro no corresponden a los mismo pacientes. Se encontró hiponatremia en cinco casos, hipopotasemia en seis casos y la cloremia estuvo dentro de límites normales. Para la determinación de la presión oncótica, se aplicó la fórmula de Bjorneboe, encontrándose en todos disminución en la presión coloido osmótica. Los datos obtenidos no permiten establecer conclusiones acerca del valor de éstas determinaciones, en el diagnóstico diferencial entre la ascitis por exudación y la de trasudación.

The effects of lactated Ringer’s solution (LRS) or LRS and 6% hetastarch on the colloid osmotic pressure, total protein and osmolality in healthy horses under general anesthesia

ObjectiveTo investigate changes in colloid osmotic pressure (COP), total protein (TP) and osmolality (OSM) during anesthesia in horses given intravenous lactated Ringer’s solution (LRS) or LRS and hetastarch (HES). Study designProspective, clinical trial. AnimalsFourteen horses presented for surgery. Mean age 8.3 ± 1.9 years; mean weight 452 ± 25 kg. MethodsHorses were premedicated with xylazine intravenously (IV); anesthesia was induced with ketamine and diazepam IV, and maintained with sevoflurane. Butorphanol was administered IV with pre-medications or immediately after induction. Xylazine was administered IV for recovery if necessary. LRS was administered IV to all horses with a target rate of 5–10 mL kg−1 hour−1. Half of the horses also received 6% HES, 2.5 mL kg−1 over 1 hour in addition to LRS. Horses that received LRS only were considered the LRS group. Horses that received both LRS and HES were considered the LRS/HES group. Blood was drawn pre- and post-anesthesia, immediately following induction, and every 30 minutes throughout anesthesia. COP, TP and OSM were measured. ResultsCOP and TP significantly decreased at similar rates for both treatment groups from pre-anesthetic values. Pre-anesthetic COP was significantly greater in the LRS group when compared to the LRS/HES group pre-, post- and throughout anesthesia. In the LRS group post-anesthetic OSM was significantly different than the pre-anesthesia value and that for the LRS/HES group. Conclusions and clinical relevanceAdministration of IV HES (2.5 mL kg−1, over 1 hour) in combination with LRS does not attenuate the decrease in COP typically seen during anesthesia with crystalloid administration alone. Based on these results, administration of HES at this rate and total volume would not be expected to prevent fluid shifts into the interstitium through its effects on COP.

Ott's protein osmotic pressure of serum and interstitial fluid in chickens (Gallus gallus): effect of age and gender

Protein, or colloid, osmotic pressure (COP) is of sufficient magnitude to exert a powerful effect on Starling forces across the capillary wall. Although avian skin lacks active mechanisms for fluid transmission, such as sweating, it is now hypothesized that passive oncotic forces may regulate fluid flow and distribution in the skin and related phenomena. In this study, serum protein profiles, as well as COP in serum (COP(s)) and in suction blister fluid (COP(sbf)), were determined in juvenile, young and adult female and male chickens. For assessing COP, the Ott-Ahlqvist equation was applied. This equation can formulate the effects of multiple serum proteins on COP, according to their molecular mass. The COP values determined in chickens were lower than those previously found in mammals. COP(s) increased with age in males, and was higher in adult males than in adult females. In contrast, COP(sbf) decreased with age in females, although it was better preserved in adult males. The age-dependent decrease in COP was associated with a parallel decrease in the concentration of α(1)-globulin and albumin, and a positive correlation between packed cell volume (PCV) and COP was found. It is concluded that ageing affects Ott's COP around the vessel wall, and that an oncotic mechanism preserves plasma volume. The preservation of COP(sbf) in males suggests better maintenance of the interstitial ground substance. Females seem to lose more of a tissue's COP(s) counteracting force than males, probably as a result of gender-specific changes in the composition of the interstitial matrix. Further studies are required to elucidate the structure and function of avian lymphatics and their role in skin rheology.

Asymptomatic pericardial effusion in patients with systemic lupus erythematosus

To determine the frequency and clinical correlates of asymptomatic pericardial effusion (PE) in patients with systemic lupus erythematosus (SLE), echocardiography and electrocardiography were performed in 50 consecutive patients with SLE. Among 50 patients with SLE, 12 patients (24%) had PE and 17 patients (34%) had hypoalbuminaemia. Patients with PE had a significantly lower serum albumin (P < 0.001), higher incidence of proteinuria (P = 0.003), higher C-reactive protein (P = 0.036) and pulmonary artery systolic pressure (P = 0.011) and tended to have a higher incidence of PR-segment depression (P = 0.082) compared with those without PE. When four variables (PR-segment depression, C-reactive protein, serum albumin and pulmonary artery systolic pressure) were used in the multivariate analysis, serum albumin (P = 0.005, odds ratio = 0.016) and pulmonary artery systolic pressure (P = 0.010, odds ratio = 1.106) emerged as significant variables related to the occurrence of asymptomatic PE. Thus, an increase in hydrostatic pressure of the right heart cavities and a decrease in colloid osmotic pressure were important factors associated with the presence of asymptomatic PE in patients with SLE.

Changes in colloid osmotic pressure as a function of anesthesia and surgery in the presence and absence of isotonic fluid administration in dogs

ObjectiveTo determine how a combination of anesthetic drugs; including pre-medication, induction agents and inhalational agents; affect colloid osmotic pressure (COP) in the presence and absence of isotonic fluid administration. Secondarily, to determine if changes in total plasma protein (TPP) correlate with COP in anesthetized patients. Study designProspective, randomized clinical study. AnimalsTen female dogs, 4 months to 4 years of age and >8 kg undergoing elective ovariohysterectomy. MethodsAll dogs were anesthetized in a similar fashion. After induction, five dogs received lactated ringer's solution (LRS) at 10 mL kg−1 hour−1 and five dogs received no fluid therapy during anesthesia. Blood samples were collected prior to pre-medication, prior to induction, immediately post-induction/prior to the inhalational agent, 30 minutes post-induction, at the time of recovery and 45 minutes post-discontinuation of inhalant. TPP and COP were measured from each sample. ResultsAdministration of fluids resulted in a decrease in COP and TPP over time that did not return to baseline by 45 minutes after recovery. Anesthesia without the administration of fluids also resulted in a significant decrease in COP over time, that was rebounding by recovery (but still significantly less than baseline). TPP had variable correlation with COP at different time points with or without fluid administration. Conclusions and clinical relevanceAnesthetic drugs alter COP similarly in the presence and absence of isotonic fluids. These changes in COP did not have a simple relationship to TPP and so the latter could not be used to predict COP in this patient population.

Beneficial Effects of Ethyl Pyruvate in Septic Shock From Peritonitis

Infusion of ethyl pyruvate (EP) solution can improve outcome in a clinically relevant, large- animal model of septic shock resulting from fecal peritonitis. Prospective randomized animal study. University hospital animal research laboratory. Fourteen female sheep. Fourteen fasted, anesthetized, invasively monitored, mechanically ventilated female sheep weighing (mean +/- SD) 30.4 +/- 3.8 kg received 0.5 g/kg of feces intraperitoneally to induce peritonitis, without administration of antibiotic agents or vasoactive drugs. After surgical preparation, the ewes were randomized to receive a continuous intravenous infusion at 15 mg/kg per hour of either EP combined with Ringer lactate solution or Ringer lactate solution only. Fluid resuscitation was titrated to maintain the pulmonary artery occlusion pressure at baseline levels throughout the experiment. All animals were monitored until they died spontaneously or for a maximum of 30 hours. Compared with Ringer lactate solution alone, EP administration resulted in less tachycardia, longer time to development of arterial hypotension and oliguria (median, 27 vs 15 hours and 24 vs 16 hours, respectively; both P<.01), and prolonged survival time (median, 29.5 vs 17.0 hours; P<.001). Animals who received EP also had a smaller decrease in colloid osmotic pressure (P<.05) and a tendency for lower serum interleukin 6 concentrations (P = .08). In this clinically relevant model of septic shock in ewes, continuous EP infusion prolonged time to development of organ dysfunction and markedly prolonged survival. These findings suggest a potential use for EP in the treatment of severe sepsis and septic shock.

Pathophysiology of oedema in idiopathic nephrotic syndrome

The decrease in plasma protein and colloid osmotic pressure (COP) in the nephrotic syndrome is accompanied by a decrease in tissue-fluid protein and COP. The latter protects against a fall in blood volume. However, the range and speed of this protective mechanism are limited, and a decrease in blood volume can be expected if plasma COP is below approximately 10 mmHg, or (temporarily) if the protein loss starts very fast. In addition, due to this protective mechanism volume retained by the kidneys cannot effectively expand blood volume, explaining that hypertension is rarely grave and pulmonary congestion unusual, whereas peripheral oedema can be gross. The renal derangement leading to volume retention involves a decreased filtration per nephron, increased tubular reabsorption, and decreased sensitivity to ANP but the relation between these changes is incompletely resolved.

The effect of membrane differential filtration on the colloid osmotic pressure in patients with age-related macular degeneration: significance to visual function?

To investigate the effect of membrane differential filtration (MDF) on plasma colloid osmotic pressure (COP) and visual functions in age-related geographic macular degeneration (AMD). Ten consecutive patients with non-exudative AMD underwent one MDF cycle. Primary endpoint was COP. Secondary endpoints were visual acuity and the mean defect of visual field. The COP was markedly reduced after one MDF cycle by 23.9% (P = 0.001). Compared with the baseline examination, visual acuity and the mean defect of visual field improved significantly after MDF. A significant positive correlation was found between the improvement in visual field and the decrease in COP (Pearson's coefficient = 0.65; P = 0.04). Membrane differential filtration lowers plasma colloid osmotic pressure in patients with non-exudative AMD. Based on the observation that visual field and COP are correlated, one may hope for a means to improve decreased central retinal function in eyes with geographic AMD by modulation of COP plasma level.

Usefulness of plasma exchange plus continuous hemodiafiltration to reduce adverse effects associated with plasma exchange in patients with acute liver failure

To efficiently remove middle-molecular-weight substances such as hepatic toxins and minimize adverse effects associated with plasma exchange implementation, we have performed plasma exchange slowly in combination with continuous hemodiafiltration. This study was designed to determine the usefulness of plasma exchange with continuous hemodiafiltration in reducing the adverse effects associated with implementation of plasma exchange alone. A retrospective clinical study. University teaching hospital. The study involved 90 patients with liver failure who had been treated with plasma exchange in our department over the past 12 yrs. We examined these patients by dividing them into two groups (48 patients treated with plasma exchange alone and 42 patients treated with plasma exchange plus continuous hemodiafiltration at the time of plasma exchange implementation). Baseline blood Na+ concentration, HCO3- concentration, and colloid osmotic pressure were followed after implementation of plasma exchange to compare the frequency of development of three adverse effects (hypernatremia, metabolic alkalosis, and sharp decrease in colloid osmotic pressure) in the two groups. Hypernatremia was found in 26.7% of treatments in the group with plasma exchange alone and 3.3% in the group of plasma exchange plus continuous hemodiafiltration, and metabolic alkalosis was found in 30.6% of treatments in the group with plasma exchange alone and 4.9% in the group of plasma exchange plus continuous hemodiafiltration; both percentages were significantly higher in the group with plasma exchange alone (p <.001). A sharp decrease in colloid osmotic pressure occurred in 13.3% of treatments in the group with plasma exchange alone but was not observed at all in the patients treated with plasma exchange plus continuous hemodiafiltration. We conclude that adverse effects associated with plasma exchange for artificial liver support for liver failure can be alleviated with use of plasma exchange plus continuous hemodiafiltration instead of plasma exchange alone.

Preventing hemodilution abolishes natriuresis of water immersion in humans.

The hypothesis was tested that hemodilution is one of the determinants of the water immersion (WI)-induced natriuresis. Eight males were subjected to 3 h of 1) WI to the midchest (Chest), 2) WI to the neck combined with thigh cuff-induced (80 mmHg) venous stasis (Neck + stasis), and 3) a seated time control (n = 6). Central venous pressure and left atrial diameter increased to the same extent during Chest and Neck + stasis (P < 0.05), whereas renal sodium excretion only increased during Chest from 77 +/- 7 to 225 +/- 13 micromol/min (P < 0.05). During Chest, plasma colloid osmotic pressure (COP) decreased from 27.7 +/- 0.7 to 25.1 +/- 0.7 mmHg (P < 0.05), and plasma volume (PV) increased from 3,263 +/- 129 to 3,581 +/- 159 ml (P < 0.05), whereas these variables remained unchanged during Neck + stasis. Plasma norepinephrine concentration decreased similarly during Chest and Neck + stasis by 45 +/- 7 and 34 +/- 4%, respectively (P < 0.05), whereas plasma renin activity decreased only during Chest (P < 0.05). In conclusion, during WI in humans 1) hemodilution (decrease in COP and increase in PV) is a pivotal stimulus for the natriuresis and 2) central blood volume expansion without hemodilution does not augment renal sodium output.

Threshold values of colloid-osmotic pressure, serum albumin or protein during perioperative period

The water flux across the capillary membrane is directly related to a gradient of hydrostatic and colloid osmotic forces. The membrane is not an absolute barrier to proteins. Any change in the capillary permeability tends to decrease the plasmatic colloid osmotic pressure. The interstitial space includes a perimicrovascular space and a compliant connective tissue space, where oedema accumulates. The lymphatics may easily drain excess filtration, but cannot clear constituted oedema. Primarily, the risk of pulmonary oedema determines the lower limit of the colloid osmotic pressure. During the perioperative period, any extrapolation of the colloid, osmotic pressure from protidaemia or albuminaemia would be approximate. Two major conclusions can be drawn from the results of Guyton and Lindsey. First, in the absence of left ventricular failure, a 50% decrease in colloid osmotic pressure does not increase extravascular lung water. Second, in the case of left ventricular failure, when the left atrial pressure exceeds 10 mmHg, a 50% decrease in colloid osmotic pressure significantly increases the risk of pulmonary oedema. In these experiments, an impairment in capillary membrane permeability is likely. As a result, the threshold at which extravascular water starts to accumulate cannot be precisely defined. However, in the perioperative period, capillary membrane permeability is frequently altered by the acute phase reaction. Finally, in most perioperative clinical situations, a 50% decrease in colloid osmotic pressure may not require any treatment.

Role of hemodilution on renal responses to water immersion in humans.

The present experiments were designed to elucidate 1) the role of the lower extremity capillary bed in decreasing plasma colloid osmotic pressure (COP) during immersion of humans (n = 8) for 6 h, and 2) the extent to which the natriuresis of water immersion is triggered by this decrease in COP. Irrespective of the depth, COPs were very similar during the immersion procedures, varying between 25.3 +/- 0.5 and 26.4 +/- 0.6 mmHg, which was significantly lower than during control (28.3 +/- 0.3 and 28.6 +/- 0.3 mmHg). During neck immersion, central venous pressure rose instantly by approximately 12 mmHg (P < 0.05) and remained elevated. Only a transient, marginal increase (1.6 +/- 0.7 mmHg) occurred during hip immersion. Cumulated sodium excretion during seated control, hip immersion, and neck immersion, respectively, differed significantly (30 +/- 5, 45 +/- 5, and 101 +/- 6 mmol). It is concluded that the decrease in COP during immersion is primarily due to fluid shifts occurring in the capillary bed of the legs and that this may account for up to 25% of the immersion-induced increase in renal sodium excretion.

Interstitial fluid volume during cardiac surgery measured by means of a non-invasive conductivity technique.

Fluid accumulation in the interstitium is frequently found after cardiac surgery. In extreme this can lead to pulmonary and myocardial oedema. The origin of this accumulation is not exactly known and may be twofold. It is probably a combination of the noninfectious whole body inflammatory response and a change in Starling forces due to a decrease in colloid osmotic pressure (COP) which is caused by the primed extracorporeal circuit. To study the changes in interstitial fluid volume (ISFV) a non-invasive conductivity technique was used. The relationship between temperature and conductivity was first investigated in vitro. A linear relationship was found between conductivity and different saline solutions and temperature. From the in vitro experiments it can be concluded that temperature corrected conductivity does not depend on haematocrit. After the in vitro experiments eleven patients undergoing cardiac surgery were studied. During the first minutes of cardiopulmonary bypass (CPB) a steep significant decrease in COP to 61.4 +/- 6.9% (from 19.6 +/- 1.1 to 12.0 +/- 1.2 mmHg), and a rise in ISFV to 105.5 +/- 2.8% (from 12.3 +/- 1.4 mS to 14.0 +/- 1.3 mS) was noticed. After this decrease COP increased significantly, till the end of the operation, but did not reach the pre-operative level. An increase in ISFV was noticed till the rewarming point. After this point no significant change in ISFV was noticed. Furthermore, a significant correlation was found between the fluid balance and the ISFV increase at the start, at the end of CPB, and at the end of the operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction in Plasma Protein Does Not Affect Body Water Content in Fetal Sheep

We performed this study to determine if isolated hypoproteinemia and low colloid osmotic pressure cause formation of fetal edema. We successfully operated on six sets of twin fetal sheep at 114 d gestation to insert catheters into arteries and veins of both fetuses, allowing us to chronically perform partial exchange transfusions. One twin underwent protein reduction by repeated partial exchange transfusion over 3 d, and the other twin underwent simultaneous sham procedures. We removed an average of 18 g of protein, causing a 41% decrease in plasma protein concentration and a 44% decrease in colloid osmotic pressure. Vascular pressures, heart rate, hematocrit, plasma osmolarity, arterial pH, and arterial PO2 were not affected by protein reduction or by sham procedure, whereas PCO2 increased by a small amount in both groups. At autopsy, none of the fetuses in either group were edematous. Measurements of total body water by the wet to dry method, chloride space, and amniotic and allantoic fluid volumes were similar in both groups. We conclude that hypoproteinemia of a short duration does not affect the body water content of fetal sheep.

PRIMING OF CARDIOPULMONARY BYPASS WITH HUMAN ALBUMIN OR RINGER LACTATE: EFFECT ON COLLOID OSMOTIC PRESSURE AND EXTRAVASCULAR LUNG WATER

We have undertaken a randomized study on 20 patients undergoing coronary artery bypass surgery in order to determine the influence of cardiopulmonary pump prime solutions on colloid osmotic pressure and extravascular lung water. Crystalloid priming with Ringer lactate was compared with an albumin solution of nearly physiological colloid osmotic composition (4%). Measurements of extravascular lung water were performed by a modified, highly sensitive thermal dye technique, with additional detection of tracer signals in the pulmonary artery. In the Ringer lactate group, a significantly greater decrease in colloid osmotic pressure occurred immediately after onset of cardiopulmonary bypass. The more pronounced decrease in colloid osmotic pressure and in transcapillary gradient (difference between colloid osmotic pressure and pulmonary capillary wedge pressure) in the Ringer lactate group was associated with a significant increase in extravascular lung water (by 60%) in the postoperative period; the human albumin group, however, showed only a slight tendency to increased lung water. There were no differences in haemodynamic or respiratory states after operation.

Influence of fluid replacement on extravascular lung water (EVLW) in patients with diabetic ketoacidosis.

Fluid replacement is a major issue in the treatment of patients with diabetic ketoacidosis. During this therapy, development of pulmonary edema has been reported and attributed to an increase in pulmonary microvascular pressure and a decrease in colloid-osmotic pressure (COP). Because clinically apparent pulmonary edema is associated with an increase in extravascular lung water (EVLW) and impairment of pulmonary gas exchange, we studied the effect of fluid replacement on EVLW, COP, pulmonary hemodynamics and gas exchange parameters in 8 patients with diabetic ketoacidosis (blood glucose greater than 300 mg/dl, pH less than 7.1). EVLW was estimated by the thermal-dye technique. All variables were successively determined upon admission (A), after initial fluid replacement (IFR), when glucose had fallen below 180 mg/dl, after 8 h of intravenous glucose treatment (G), and after 24 h of total parenteral nutrition (TPN). Despite a total net fluid intake of 6.0 +/- 1.61, a significant decrease (p less than 0.001) in COP from 29.6 +/- 5.5 at A to 18.8 +/- 2.2 mmHg after TPE and a significant increase (p less than 0.001) in PCWP from 4 +/- 2 at A to 10 +/- 3 mmHg after TPE, EVLW remained almost unchanged. EVLW was 5.1 +/- 2.8 at A, 5.3 +/- 2.1 after IFR, 4.8 +/- 1.4 after G, and 5.3 +/- 1.7 ml/kg after TPN. However, PaO2 decreased from 137 +/- 17 at A to 87 +/- 10 mmHg after TPE (p less than 0.001), while Qs/Qt increased significantly (p less than 0.05). The alterations in gas exchange may be indicative of pulmonary dysfunction but as they were not associated with accumulation of EVLW, they may as well reflect the compensation of metabolic derangements in diabetic ketoacidosis.