Post-traumatic changes in, and effect of colloid osmotic pressure on the distribution of body water.

The aim of this study was to define the post-traumatic changes in body fluid compartments and to evaluate the effect of plasma colloid osmotic pressure (COP) on the partitioning of body fluid between these compartments. Forty-two measurements of plasma volume (green dye), extracellular volume (bromine), and total body water (deuterium) were done in ten traumatized patients (mean Injury Severity Score, ISS, = 34) and 23 similar control studies were done in eight healthy volunteers who were in stable fluid balance. Interstitial volume, intracellular volume, and blood volume were calculated from measured fluid spaces and hematocrit; COP was directly measured. Studies in volunteers on consecutive days indicated good reproducibility, with coefficients of variation equal to 3.5% for COP, 6.3% for plasma volume, 4.5% for extracellular volume, and 4.9% for total body water. COP values extended over the entire range seen clinically, from 10 to 30 mmHg. Interstitial volume was increased by 55% in patients, but intracellular volume was decreased by 10%. We conclude (1) that posttraumatic peripheral edema resulting from hemodilution is located in the interstitial compartment, with no intracellular space expansion; and (2) that interstitial volume, but not intracellular volume, is closely related to plasma COP.

The effect of colloid osmotic pressure on the survival of sheep following cardiac surgery.

The occurrence of late complications in implanted cardiac prosthetic valves has emphasized the need for the development of an animal model in which these complications are reproducible. Sheep constitute an excellent model for chronical and pathological studies of prosthetic devices. In our experience, survival of sheep following implantation of prosthetic valves is closely related to postoperative serum colloid osmotic pressure (C.O.P.). The normal range as measured in 28 healthy sheep was 16.67 +/- 0.55 mm Hg. A protocol was developed to maintain the colloid hydrostatic pressure gradient (C.H.P.G.) as close as possible to the normal physiological range, and to delay the extubation until the C.O.P. was within this range, and the C.H.P.G. greater than 7 mm Hg. Using the above protocol, a new tri-leaflet polyurethane valve was inserted into eight, five to seven month old sheep in place of the mitral and tricuspidal valves. One hour after terminating the extacorporeal circuit, the C.O.P. was measured at 13.10 +/- 0.96; but within five to six hours, it rose to 17.1 +/- 1.1. During the same period, the C.H.P.G. increased from 3.02 +/- 0.96 to 7.6 +/- 0.50 mm Hg. The postoperative period was uneventful, and all animals survived. We have thus concluded that the routine measurement and monitoring of C.O.P. constitutes a guide of great clinical importance.

PVP-sieving curves as an estimate of glomerular hemodynamics in HgCl2 acute renal failure in the dog.

In the present study, the pathophysiologic role of glomerular hemodynamic factors in the early phase of HgCl2-induced acute renal failure is evaluated in the dog. This model of moderate ARF is characterized by a parallel fall in glomerular filtration rate (delta GFR, -43%) and renal blood flow (delta RBF, -38%) within the first three hours after HgCl2 administration. Glomerular hemodynamics were studied by analysis of PVP-sieving curves. There was a significant shift of these curves upward and to the right during the 3 hours that followed the injection of HgCl2. From this analysis, no arguments for tubular back-leak could be found. Mathematical analysis of the curves revealed a fall in effective filtration pressure (EFP) in presence of an unchanged glomerular ultrafiltration coefficient (Kf) (delta EFP, -40 +/- 4%; p less than 0.01; delta Kf, +5 +/- 1%; p greater than 0.05 vs. control). No major changes occurred in glomerular colloid osmotic pressure. Subsequently, the early fall of GFR in this toxic model of acute renal failure was essentially attributed to a decrease of effective filtration pressure due to either tubular obstruction and/or mainly to renal hemodynamic changes.

The importance of plasma colloid osmotic pressure for interstitial fluid volume and fluid balance after elective abdominal vascular surgery.

The relationships between plasma colloid osmotic pressure (COPp) and interstitial fluid volume (IFV) as well as postoperative fluid balance were investigated in a prospective study involving 53 patients undergoing elective abdominal aortic reconstruction. The patients were divided into four groups according to pre- and postoperative blood replacement and fluid therapy programs whereby a continuum of postoperative COPp-values between 33 and 16 mmHg was obtained. Measurements were done before the operation and on days 1 and 4 after surgery. After surgery, COPp below 20 mmHg led to increased IFV. On day 1, COPp was linearly correlated to the total amount of fluid retained during the day of operation. A positive fluid balance of 3 L on this day ensured unchanged extracellular fluid volume (ECV). Of the 3 L, 1.5 L was insensible water loss and 1.5 L had moved into the cells. On day 4 after surgery, COPp below 22 mmHg was associated with increased plasma volume. The authors suggest that COPp be maintained above 20 mmHg after major surgery, and positive fluid balance should not exceed 5 L during the day of operation.

Correlation between measured and calculated colloid osmotic pressure.

We examined the relationship between measured colloid osmotic pressure (COP), and COP calculated from serum total protein concentration (TP). Serum COP and TP were measured in 40 patients with severe abdominal sepsis. Measured COP values were not significantly different from values calculated using three separate formulas. The correlation rate between measured COP and TP (r = .83, p less than .01) was lower than that between calculated COP and TP (r = .99, p less than .01). All three formulas were fairly reliable. Alternatively, a table of predicted COP values may be useful in severely ill patients.

Peripartum colloid osmotic pressure changes: effects of controlled fluid management.

A prospective, fluid-controlled study of serially measured colloid osmotic pressure changes in the peripartum period was undertaken. Seventeen patients with uncomplicated pregnancies undergoing elective cesarean section at term were administered a predelivery bolus of 15 ml/kg of lactated Ringer's solution prior to operation. Maintenance crystalloid fluids were infused at 125 to 150 ml/hr both intraoperatively and post partum without the addition of blood or other colloid solutions. Serial colloid osmotic pressure measurements were obtained before hydration, after hydration, after delivery, and at 6 and 24 hours post partum. The results demonstrated a 15.9% decline in colloid osmotic pressure immediately following the hydration bolus (20.7 +/- 1.5 to 17.4 +/- 1.8 mm Hg) (p less than 0.01). A further decline in colloid osmotic pressure to 16.6 +/- 1.7 mm Hg occurred after delivery and represented an overall 22% decrease from the baseline value (p less than 0.05). The lowest mean colloid osmotic pressure value occurred at 6 hours post partum (16.1 +/- 1.1 mm Hg). These data support previous observations that colloid osmotic pressure is uniformly lowered in the immediate postpartum period with peak reductions identified at 6 hours following delivery. In addition, intravenous crystalloid administration during the peripartum interval can substantially influence this decline in colloid osmotic pressure. Although no clinical evidence of cardiopulmonary compromise was observed in this set of normal gravid women, these data may be useful in the management of the parturient patient with established risk factors for pulmonary edema where alterations in the pulmonary capillary wedge pressure-colloid osmotic pressure gradient have been shown to correlate with the development of this complication.

Protein and colloid osmotic pressure changes with albumin and/or saline replacement during plasma exchange.

Colloid osmotic pressure (COP) has been used as a predictor of fluid egress from the vascular space and edema development in the lungs and elsewhere. We investigated the relative safety, as predicted by the COP, of 5 percent albumin plus saline and 5 percent albumin alone as replacement fluids during plasma exchange. Fifty-three one and one-half plasma volume exchanges were performed in 15 patients with a variety of diagnoses using intermittent flow cell separators. On specimens obtained, before, during, and after each plasma exchange, the COP was measured directly with a membrane oncometer , and total protein, albumin, and protein electrophoresis were determined using standard biochemical techniques. COP dropped significantly with one to one 5 percent albumin replacement but even more with one-half 5 percent albumin and one-half saline replacement during the exchange. COP did not fall below 12.5 torr at the end of the plasma exchange, even with one-half saline replacement, compared to the 10 to 12 torr level at which pulmonary edema might be expected. The fall in COP during exchange when saline was given first did approach this range but rapidly reversed itself with albumin administration. Clinically, no evidence of tissue or pulmonary edema was observed. Recovery in total protein and COP between plasma exchanges was significant.

Canine blood volume and cardiovascular function during hyperthermia.

The effect of acute hyperthermia on hemodynamic functions and blood volume regulation was examined on eight splenectomized dogs. Elevation of core body temperature by 2 degrees C over 90 min caused significant increase in cardiac output (11.2 +/- 12.5 ml X min-1 X kg-1 or about 10%) and significant decrease in total peripheral resistance (TPR; -1.3 +/- 1.0 mmHg X s X ml-1 or about 20%), whereas blood volume (BV), plasma oncotic pressure, and intravascular protein mass remained unchanged. Thus the raised core temperature caused peripheral vasodilation with decreased TPR and compensatory increase in cardiac output. Because BV remained unchanged during warming, mobilization of extravascular fluid did not occur; only the redistribution of blood to the vasodilated cutaneous circulation took place. To assess the effects of heat stress on transvascular fluid equilibrium, Ringer solution (10.7 ml X kg-1 X 10 min-1) was infused under normothermic and hyperthermic conditions. The volume of fluid retained within the intravascular space under equilibrium state was 33.5% in hyperthermia and 9.4% in normothermia. In hyperthermia, the transvascular fluid shift and urinary output were decreased both during and after infusion. The role of preferential fluid retention within the intravascular space observed during hyperthermia was discussed in relation to the mechanism to maintain cardiovascular function and BV under heat stress.

[Colloid osmotic pressure--a parameter of postoperative protein therapy. A pilot study]. / Kolloidosmotischer Druck--Ein Parameter zur postoperativen Eiweisstherapie. Eine Pilotstudie.

120 intensive-care patients were examined postoperatively in a pilot study. The patients were divided into two groups. In group 1 human albumin was given when the serum protein concentration decreased below 5 g%, in group 2 when the colloid osmotic pressure (COP) decreased below 27 cmH2O. Patients of group 2 received less human albumin, but despite the lower human albumin supply these patients did not worse postoperatively as compared to group 1. On the contrary, the trend could be observed that the periods of ventilation were shorter (possibly due to the lower volume load of the patients) and the serum creatinine concentrations were lower (possibly due to the increased supply of crystalloid solutions) if smaller amounts of albumin were given. It may be concluded that the postoperative human albumin supply is unnecessary if the COP ranges 27 cmH2O or more.

Assessment of alveolar-capillary membrane permeability of dogs by aerosolization.

We developed a method for measuring an index of alveolar-capillary membrane permeability (PI) by aerosolizing a mixture of 99mTc-diethylenetriaminepentaacetic acid (Tc-DTPA) and 125I-antipyrine (I-AP) and injecting 111In-DTPA (In-DTPA). The I-AP was used to compute the quantity of Tc-DTPA delivered and the In-DTPA the quantity of Tc-DTPA in the body. The PI was the ratio of the uptake of Tc-DTPA per minute to the amount deposited at the end of aerosolization. In 14 anesthetized dogs we measured the volume of distribution of I-AP (0.54 +/- 0.034 l/kg body wt) and/or showed that the volumes of distribution of Tc-DTPA and In-DTPA were similar. We measured PI in four groups of dogs: control (n = 5), oleic acid (n = 5), hydrochloric acid (n = 6), and high left atrial pressure (n = 5). The PI increased significantly in both groups with acid-induced increased permeability compared with the control and high left atrial pressure groups, which did not differ from each other. We conclude that the aerosolization method is suitable for differentiating increased from normal permeability.

Interstitial fluid volume, colloid osmotic and hydrostatic pressures in rat skeletal muscle. Effect of hypoproteinemia.

Colloid osmotic pressures in plasma (COPp) and interstitial fluid (COPi), interstitial fluid pressure (Pi) as well as interstitial fluid volume (IFV) was measured in rat skeletal muscle during development of hypoproteinemia. The hypoproteinemia was induced with intraperitoneal injections of aminonucleoside puromucin causing a renal lesion similar to that in human nephrotic syndrome with renal loss of plasma protein and subsequent fall in COPp. When COPp fell from control values (about 20 mmHg) to about 10 mmHg, the fall was accompanied by an identical fall in COPi (in mmHg) while Pi did not change. Provided the pre- to postcapillary resistance ratio was unchanged, the pressure imbalance in the Starling forces (net filtration pressure) was similar to the control situation at this stage of the hypoproteinemia. With further fall in COPi, the absolute fall in COPi was less, - leading to increased net filtration pressure, and finally edema appeared. In presence of edema, Pi rose from average control values of -0.20 mmHg to an average of +1.5 mmHg. Interstitial fluid volume in hypoproteinemic rats without edema was similar to that of controls (about 0.30 ml/g dry tissue), and increases to 3 to 4 times this value in the presence of edema. Comparing the fall in COPi to IFV in the nephrotic rats without edema show that the fall in COPi must have been brought about by a lymphatic washout of interstitial proteins since IFV was similar to the controls when COPi had fallen to 1/3 that of control.

Plasma oncotic pressure and plasma protein concentration in patients following thermal injury.

Plasma oncotic pressure (POP), albumin and total protein were measured in 14 patients with thermal injuries varying extent from 16 to 90% of the body surface. The patients were treated with large amounts of balanced salt solutions in the initial phase. There was an abrupt, pronounced decrease in POP to about 51% of the normal during the first 24 h. Despite the low POP values (minimum 0.78 kPa) and marked peripheral oedema, no patient had overt pulmonary oedema. Clinical and roentgenological evidence of pulmonary dysfunction during the initial period was only seen in conjunction with lung burn or aspiration pneumonitis. Oedema-preventing mechanism and inability to detect interstitial pulmonary oedema are discussed as possible explanations. There was no significant correlation between decrease in POP and mortality, but low POP values seemed to persist longer in the patients who died.

Heparin induced alterations in clearance and distribution of blood-borne microparticles following operative trauma.

The influence of systemic heparin administration on the vascular clearance and tissue distribution of blood-borne microparticles was evaluated in normal rats and rats after operation (laparotomy plus intestinal manipulation) utilizing an (131)I- colloid which is phagocytized by the reticuloendothelial system (RES). Intravenous heparin administration (100 USP/100g body weight) into normal animals three minutes prior to colloid injection (50 mg/lOOg) induced a significant increase in pulmonary localization of the microparticles as compared to nonheparinized control rats, while hepatic and splenic uptake were decreased. Surgical trauma decreased hepatic RE uptake and increased pulmonary localization of the microparticles when injected systemically at 60 minutes postsurgery. Heparin administration 60 minutes after surgery and three minutes prior to colloid injection, magnified the increased pulmonary localization response with an associated further depression of the RES. The ability of heparin to alter both RE clearance function and lung localization of microparticles was dose dependent and a function of the interval between heparin administration and systemic particulate infusion. Thus, low dose heparin administration was capable of stimulating RE activity while heparin in doses of excess of 50 USP units/lOOg body weight decreased RE function. These findings suggest that the functional state of the hepatic RE system can be greatly affected in a dose-dependent manner by systemic heparin administration which may influence distribution of blood-borne microparticles.

[Generalized peritonitis. Morbidity and mortality with respect to the development of oncotic pressure in the early postoperative period]. / Peritonitis generalizada. Morbilidad y mortalidad con respecto al desarrollo de la presion oncotica en el postoperatorio temprano.

A group of forty patients with generalized peritonitis was studied comparing their clinical evolution and mortality with the plasma coloidosmotic pressure values (COP). Twentynine patients survived without complications (Group I) this patients had the higher mean COP values, 17.56 mm Hg at the beggining and 19.06 mm Hg at the end of the study. Three patients showed complications directly related with peritonitis but finally survived (Group II). Their mean COP values were 16.08 mm Hg at the beggining and 13.44 mm Hg at the end. Eight patients died (Group III) lower mean COP values were obtained in this group; 13.5 at the begging and 11.94 at the end. Despite the same kind of medical and surgical treatment, response was very different in each group. Lower values of COP were found as clinical avolution worsened. A very low inicial value or failure to raise it despite the treatment may be considered as a bad prognosis sing.

Interactions of intestinal lymph flow and secretion.

The relationship between lymph flow and intestinal secretion was studied in an isolated, vascularly perfused cat ileal preparation in which secretion was caused by three different means: 1) plasma dilution from a constant infusion of Tyrode solution (2.5 ml/min per kg), 2) elevation of intestinal venous pressure to 30 mmHg, and 3) exposure to cholera toxin. In the plasma-dilution group, lymph flow attained a peak value of 38 times control at 60-90 min following the onset of the infusion, after which time lymph flow progressively decreased. Concomitant to the rapid decrease in lymph flow was a rapid increase in intestinal secretion (filtration secretion). A similar pattern, i.e., a rapid increase in lymph flow followed by a progressive decrease in lymph flow and concomitant increase in filtration secretion, was observed in the venous hypertension group; however, peak lymph flow (20 X control) was observed within 10 min of the pertubation. No correlation between the onset of intestinal secretion and a decline in lymph flow was observed in the cholera toxin group.