Concurrent expansion of plasma volume and left ventricular end-diastolic volume in patients after rapid infusion of 5% albumin and lactated Ringer's solution

STUDY OBJECTIVE: To examine the effects of plasma volume expansion on plasma volume, left ventricular end-diastolic volume (LVEDV), and cardiac index (CI) after rapid fluid infusion, as knowledge of the degree of concordance between plasma and cardiac preload expansion could optimize LVEDV expansion without administering excessive fluid. DESIGN: Randomized, double-blinded study. SETTING: Academic community hospital. PATIENTS: 20 patients undergoing elective coronary artery bypass surgery. INTERVENTIONS: Patients were administered either 5% albumin (5 mL/kg) or lactated Ringer's solution (25 mL/kg) over 30 minutes, just before incision. MEASUREMENTS: Serial measurements of plasma volume, LVEDV by transesophageal echocardiography, and CI were recorded. MAIN RESULTS: Albumin expanded plasma volume and LVEDV to a similar degree (11.3% and 13.2%). In contrast, lactated Ringer's solution increased plasma volume more than LVEDV (21.7% vs 14.4%; P = 0.0005). Increased LVEDV significantly but poorly correlated with increased CI (r(2) = 0.2, P < 0.0001) for both fluids. However, LVEDV expansion was brief and returned to baseline or less within 30 minutes for both fluids despite continued plasma volume expansion and increased CI. Correspondingly, rates of decline from peak expansion were significantly faster for LVEDV than plasma volume expansion for both albumin (-1.9% + 1.9%/min vs -0.1% + 0.1%/min; P = 0.0008) and lactated Ringer's (-1.1% + 0.8%/min vs -0.4% + 0.2%/min; P = 0.006). CONCLUSIONS: Intravenous fluids increased LVEDV to a lesser extent and duration than did plasma volume expansion. Monitoring of LVEDV was a poor guide for fluid administration to maximize CI.     

Changes in serum albumin concentration and volume expanding effects following a bolus of albumin 20% in septic patients

Background. Patients with systemic sepsis develop a capillaryleak syndrome, and serum –albumin concentration decreases.Hyperoncotic albumin infusion can be used for volume expansionin these patients, but the degree and duration of effect arenot well described. We assessed volume expansion by albumin20% infusion and compared the retention of infused albumin inseptic patients and healthy controls. Methods. We gave albumin 20%, 200 ml as a rapid infusion to70 patients with septic shock and 26 controls. Blood sampleswere taken before and 1, 5, 15, 30, 60, 120 and 240 min afterthe infusion for measurement of serum albumin concentrationand haematocrit. Haemodilution and the percentage of administeredalbumin remaining intravascularly at each time were calculated. Results. The mean proportion of the increase in albumin remainingat 4 h was 68.5 (SD 10)% in septic patients and 79 (5)% in controls(P<0.001). The albumin 20%, 200 ml caused a secondary fluidresorption and volume expansion maximal at 30 min, equivalentto a 430 ml infusion in septic patients and 500 ml in controls. Conclusions. After giving albumin, serum albumin concentrationsdecrease significantly faster in septic patients than in healthycontrols. Br J Anaesth 2004; 92: 821–6     

Increased hair growth and density following controlled expansion of guinea pig skin and soft tissue

The goal of this study was to investigate the effect of controlled tissue expansion on hair growth and density using the guinea pig model. Thirty white guinea pigs were randomly divided into three groups: a group to undergo expansion (EXP), an operated control group (OC), and a nonoperated control group (NOC). All groups were shaved to create a 1 cm X 2 cm tuft of dorsal hair, which was subsequently dyed. Only the EXP and OC group members underwent construction of a pocket beneath the tuft. Only the EXP group was implanted and expanded over four weeks. The EXP group revealed a significant increase (p less than 0.005) over the controls in both the number of new white hairs produced (W) and density proportion (W/A). The OC group exhibited a significant increase (p less than 0.005) over the NOC group in both W and W/A. Mechanisms to explain the results are postulated. These include the possible roles of increased follicular mitotic activity (hair follicle transformation and cycle dynamics) and improved perifollicular vascularity (capsule formation and the delay phenomenon of skin pocket construction). Clinical implications are discussed.     

Stapedectomy in the guinea pig.

Stapedectomy has traditionally been studied in the feline model. Ethical considerations and costs have made this model less feasible for ongoing research. The purpose of this study was to examine the guinea pig as a model for research on stapedectomy. Technical difficulties included limited exposure and small dimensions of the ossicles. The surgical technique with and without the use of a CO(2) laser and the relevant anatomy of the guinea pig middle ear are described.     

Resorption rate and biocompatibility characteristics of two polyester ventilation tubes in a guinea pig model

OBJECTIVES: Determine the resorption rate and biocompatibility characteristics of 2 polyester ventilation tubes, and to determine whether soap and water exposure accelerates polyester tube degradation. STUDY DESIGN AND SETTING: 50/50 poly (D, L-lactide-co-glycolide; PLGA-50) and poly (L-lactide; PLA) polymers were placed into the tympanic membranes of Hartley pigmented guinea pigs. Integrity of the tubes was determined by weekly otoscopic examination. Biocompatibility was assessed by comparing auditory brainstem response (ABR) thresholds and by examining tympanic membrane changes following tube resorption. Shah minigrommet ventilation tubes were used as controls. In the second portion of this study, implanted PLGA-50 and PLA tubes were exposed weekly to a mixture of soap and water (1:5) until complete resorption was observed. Biocompatibility was assessed by periodic ABR testing and tympanic membrane examination. RESULTS: The PLA tubes remained in the tympanic membrane for a longer period (63.2 +/- 19.3 days) than the PLGA-50 (18.8 +/- 8.1 days). The tympanic membrane and resorbable tube interface demonstrated equivalent findings for auditory thresholds and tissue histopathology at the implant site compared to nonresorbable controls. The resorption behavior was not altered by exposure to soap and water. Tympanic membranes of all animals following tube degradation and soap water exposure were intact with minimal scarring and no signs of persistent foreign body response. The histological analysis showed that implantation of resorbable tubes was not accompanied by secondary infection with otorrhea through the tube, did not result in a permanent perforation or dislocation of the tube into the middle ear cavity, and was not followed by excess tympanosclerosis or localized or diffuse membrane atrophy. CONCLUSIONS AND SIGNIFICANCE: Resorbable polyester pressure equalization tubes demonstrate predictable resorption behavior and similar biocompatibility characteristics when compared with nonresorbable Shah minigrommet ventilation tubes. Exposure to soap water does not accelerate polyester tube degradation nor change the host tissue response during the indwelling period or after complete resorption. The data suggests that resorbable ventilation tubes are substantially equivalent to other FDA-approved tympanostomy devices with regard to safety and biocompatibility in the guinea pig model examined and may provide improved clinical performance by combining this approach with sustained release technology. EBM RATING: B-2.     

Plasma volume after dextran infusion in rats sensitive and non-sensitive to dextran.

Plasma volume determinations were done with RIHSA under normal conditions and after intravenous infusion of dextran solutions. The plasma volume of normal rats in millilitre was found to be 0.026 X body weight + 0.92. Infusion of dextran into dextran-sensitive Sprague-Dawley rats was followed by a marked plasma volume reduction and haemoconcentration as consequence of an anaphylactoid reaction. This reaction could be partially inhibited by pretreatment with cyproheptadine chloride. Plasma volume determination with the method used in this study can be used to evaluate the dextran-anaphylactoid reaction. In dextran non-sensitive Wistar rats, infusion of dextran had a strong plasma volume-expanding effect comparable to the plasma volume-expanding effect of dextran in humans. No signs of abnormal leakage of fluid out into the extravascular space were evident, which indicated that the Wistar rats really were non-sensitive to dextran.     

Diabetes mellitus in the guinea pig.

Spontaneous diabetes mellitus has been documented in a colony of guinea pigs. The contagious nature of the disease has been verified, but the nature of the infectious agent is not known. Animals from the original colony or animals exposed to the colony with normal glucose tolerance tests (GTT) became diabetic, as evidenced by elevated one- and four-hour GTT values, and in most cases have significant glycosuria. The severity of pathologic changes in the pancreatic islets parallel, in general, the severity of the clinical symptoms (glycosuria and abnormal GTT). Those animals with severe glycosuria and elevated FBS as well as one- and four-hour GTT values had the most pronounced degranulation and most prominent cytoplasmic inclusions in islet B cells. The severity of scarring in the islets can be correlated with the duration of the overt diabetic state. The other clinical parameters of note were elevated serum triglycerides, normal serum but elevated aortic cholesterol, and absence of ketonemia or ketonuria. The reproductive capacity of diabetic females was compromised. While the clinical manifestations are mild or variable, the presence of significant islet pathology is reminiscent of human juvenile diabetes mellitus. These findings lend support to the concept that infectious and/or immune mechanisms could be operative in the etiology and pathogenesis of human diabetes mellitus.     

The effect of plasma volume expansion on uteroplacental blood flow in hypertensive pregnancies

The effect of plasma volume expansion on uteroplacental blood flow was investigated in 20 hypertensive women in the 3rd trimester of pregnancy by measuring the radioactivity in the region of the placenta with a gamma camera after an intravenous injection of indium-113. Despite a significant increase in plasma volume there was no change in maternal blood pressure or in uteroplacental blood flow. This suggests an autoregulation of both blood pressure and uteroplacental blood flow.     

Effects of plasma volume expansion on renal salt handling in patients with the nephrotic syndrome

In 10 patients with the nephrotic syndrome (NS) and edema persisting despite a NaCl-poor diet, the effect of a single infusion of hyperoncotic albumin (75 g) on NaCl excretion was studied. 6 patients had minimal lesions, and 2 patients were studied twice. On half of the occasions the glomerular filtration rate was reduced. Blood volume (BV), calculated from plasma volume and hematocrit, was slightly elevated before infusion, and increased to 136 and 120% of normal at 4 and 20 h after it, respectively. Plasma renin activity (PRA) and plasma aldosterone (PA) both decreased to suppressed levels at 20 h after infusion. Sodium excretion increased from 9.2 +/- 7.6 muEq/min before, to 3.10 +/- 22.4 (0-4 h) and 43.1 +/- 36.3 muEq/min (4-20 h) after infusion. In 6 of these patients clearance studies were done before and after the infusion, maximal free water clearance being used as marker for distal NaCl reabsorption. Proximal fractional NaCl reabsorption was elevated before (94.9 +/- 1.4%) and decreased after the infusion (92.8 +/- 1.7%). Distal fractional NaCl reabsorption was also elevated before (93.0 +/- 6.4%), but unaltered after infusion (93.0 +/- 5.6%). Thus, after marked expansion of BV and suppression of PRA and PA, sodium excretion remained low despite the present edema. The results indicate that in many patients with the NS, including minimal lesion NS, intravascular hypovolemia is not the sole cause of sodium retention.     

Tumor necrosis factor and interleukin 1 appearance in experimental gram-negative septic shock. The effects of plasma exchange with albumin and plasma infusion

To study the effect of plasma removal vs plasma administration on the appearance of tumor necrosis factor (TNF) and interleukin 1 in septic shock, 24 anesthetized piglets were inoculated with live Escherichia coli. Plasma exchange with albumin was performed in one group. Fresh-frozen plasma was administered to a second group. A third group served as nontreated controls. Following plasma exchange, a reduction in both TNF and interleukin 1 levels occurred, whereas plasma infusion was followed by a decrease in TNF levels only. No significant differences were observed between the two treated groups with respect to survival or cardiovascular performance, with both being significantly enhanced compared with the controls. High levels of TNF and interleukin 1 correlated with depressed cardiovascular performance in the early phase of the shock. Our results confirm the important role of TNF and interleukin 1 as early mediators of septic shock. However, the benefit of reducing cytokine activity in later stages of septicemia seems to be dubious.     

Labyrinthine fenestration in the guinea pig.

OBJECTIVE: To evaluate the auditory effects of single, double, and triple semicircular canal fenestration procedures, with and without sealing the labyrinthine defect. BACKGROUND: Violation of the inner ear remains a feared complication in otologic surgery because it commonly leads to profound sensorineural hearing loss. It has been assumed that the natural history of labyrinthine injury in the guinea pig is similar to that in human beings; however, this assumption has not been rigorously studied. DESIGN: Prospective, randomized, and controlled animal study. SUBJECTS: Sixty pigmented guinea pigs. OUTCOME: Click-evoked electrocochleographic response, with same-ear prefenestration control. RESULTS: All of the fenestration groups had elevated auditory thresholds at 1 hour when compared with controls (P < 0.01); however, this difference lost statistical significance at 1 and 4 weeks. The degree of labyrinthine injury did not correlate with the degree of hearing loss or with the incidence of anacusis. Hearing remained stable during the study period. Sealing the fenestration had no significant audiologic effect (P > 0.40). CONCLUSIONS: The guinea pig model of labyrinthine fenestration may not be representative of the human condition.     

Examination of the role of the colloids hydroxyethylstarch, dextran, human albumin, and plasma proteins in a modified UW solution.

The delayed contralateral nephrectomy procedure (three-step) produced inconsistent results, indicating that the preserved autotransplanted kidney tends to remain unfunctional and to regenerate incompletely unless the demand for work is placed upon it. Omission of HES in UW (UW-plain) did not affect preservation success, but resulted in increased graft edema. Substitution of HES in UW with plasma (SGF-V) or albumin (MAlb) gave significantly worse results than UW-like solutions with or without synthetic colloids. Replacement of HES in UW with UMdex-70 or UMdex-500 gave nonsignificantly worse results than UW-like solutions with or without synthetic colloids. The use of UMdex-40 as the main colloid in UW cheapened the solution, equalled the preservation success of UW and UW-plain but surpassed UW-plain in edema prevention, and exceeded UW concerning recovery of graft microcirculation.     

Infusion of albumin attenuates changes in serum protein binding of drugs in surgical patients compared with volume replacement with HAES

Background: In vitro studies have indicated that stabilizers present in pharmaceutical-grade albumin influence albumin-binding capacity for highly protein bound drugs.
Methods: A randomized study including 40 surgical patients, treated with either albumin or starch solutions, was performed. Volumes of colloids were given based on clinical indication. Blood samples were obtained. The serum samples were analyzed to determine the concentrations of albumin, tryptophan, N -acetyl- dl -tryptophan, caprylate and α-1-acid glycoprotein as well as in vitro drug binding of naproxen, warfarin and digitoxin.
Results: During surgery, the albumin concentration declined in the Starch group from 26.8 to 15.3 g/l. It remained unchanged in the Albumin group (29.2 g/l). The two groups were analyzed with the pre-operative sample acting as the control. In the starch group, the percent free concentration of the drugs increased significantly ( P <0.01): for naproxen from 0.2% to 0.6%, for warfarin from 1.2% to 1.8% and for digitoxin from 6.8% to 11.1%. In the Albumin group, the % free fraction of naproxen doubled from 0.1% to 0.2% ( P <0.05), whereas the % free fraction of warfarin decreased from 1.1% to 1.0% ( P <0.05). The free fraction of digitoxin remained unchanged.
Conclusions: Infusion of albumin during surgery resulted in maintained albumin values and almost maintained binding parameters for the study drugs, although some statistically significant changes were found. The use of starch solutions, however, led to in a reduction in albumin values and a significant reduction in binding parameters.