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Retrograde autologous priming: is it useful in elective on-pump coronary artery bypass surgery?

BACKGROUND: The effect of reduced cardiopulmonary bypass (CPB) prime volume by retrograde autologous priming (RAP) was studied. METHODS: Twenty patients undergoing elective coronary artery bypass grafting were randomized to either standard prime (SP) volume (1,602 +/- 202 mL crystalloid prime, n = 10) or RAP (395 +/- 150 mL). RAP was performed by draining crystalloid prime from the arterial and venous lines into a recirculation bag before CPB. Cardiac index, pulmonary vascular resistance index, systemic vascular resistance index, alveolar-arterial oxygen tension difference, pulmonary shunt fraction, extravascular lung water (EVLW), plasma colloid osmotic pressure (COP), crystalloid fluid balance, body weight, and clinical parameters were evaluated perioperatively. RESULTS: Demographic data and operative parameters were equal for patients in both groups. During CPB, COP was reduced by 55% in the SP group (9.8 +/- 2.0 vs 21.4 +/- 2.1 mm Hg) and by 41% in the RAP group (12.4 +/- 1.1 vs 20.9 +/- 1.8 mm Hg) (p = 0.008, SP vs RAP group). Compared with preoperatively, EVLW was unchanged in the RAP group 2 hours post-CPB, but it was elevated by 21% in the SP group (p = 0.002, SP vs RAP group). End-CPB crystalloid fluid balance was significantly reduced in the RAP group (1,857 +/- 521 vs 2,831 +/- 637 mL). Postoperative (day 2) weight gain in the SP group (1.5 +/- 1.2 kg, p = 0.021) was absent in the RAP group (0.1 +/- 0.9, NS). Postoperative time to full mobilization was shorter in the RAP group. Postpump cardio-respiratory function did not differ among groups. CONCLUSIONS: This small-scale pilot study indicates that by reducing crystalloid fluid administration and fall of COP during CPB, RAP reduces postpump EVLW accumulation and weight gain in uncomplicated coronary artery bypass graft patients with no associated effects on cardio-respiratory function.

Blood Transfusion, Autologous↗

Plasma volume substitution.

Blood loss up to 10-15% of the total blood volume can be substituted by mere crystalloids. A quicker and more stable volume replacement can be accomplished with colloid solutions. Combination of artificial colloids (e.g., dextran 60, dextran 70 or hydroxyethyl starches with high degree of hydroxyethylation) with crystalloids (isotonic balanced solutions) produces a long lasting volume effect. Due to dose limitation recommendations for the artificial colloids, volume substitution may be continued, at a later stage, by albumin.

Blood Volume↗

Isolyte S, a physiologic multielectrolyte solution, is preferable to normal saline to wash cell saver salvaged blood: conclusions from a prospective, randomized study in a canine model.

OBJECTIVES: The purpose of this study is to compare normal saline with Isolyte S as the wash solutions during high-volume cell saver autologous blood transfusion. Normal saline, the standard wash solution in cell saver autologous blood transfusion, is associated with acid-base and electrolyte derangements. Isolyte S is a physiologic, balanced multielectrolyte crystalloid solution that approximates the electrolyte content of plasma. DESIGN: Open-label, prospective, randomized study. SETTING: Research laboratory in a Department of Veterans Affairs medical center. SUBJECTS: Fourteen mongrel dogs, weighing 22 to 23 kg each. INTERVENTIONS: Fourteen mongrel dogs were prospectively randomized to receive normal saline (n = 7) or Isolyte S (n = 7). Animals were anesthetized, received heparin for anticoagulation, and underwent 18 cycles of cell saver autotransfusion. In each cycle, 125 mL of blood was arterially withdrawn, and washed with either normal saline (mEq/L) (sodium 154, chloride 154) or Isolyte S (mEq/L) (sodium 141, potassium 5, magnesium 3, chloride 98, phosphate 1, acetate 28, and gluconate 23). The washed blood was retransfused. MEASUREMENTS AND MAIN RESULTS: Acid-base and electrolyte analyses were performed throughout the study on the systemic blood of each group and compared. By the end of the study, the Isolyte S group had a normal pH and an increased bicarbonate concentration (mEq/L: normal values 24 to 32; normal saline 9.0 +/- 1.9 vs. Isolyte S 13.2 +/- 3.0 [p < .01]) and an increased magnesium concentration (mg/dL: normal values 1.6 to 2.4; normal saline 1.6 +/- 0.2 vs. Isolyte S 2.2 +/- 0.2 [p < .0001]). Additionally, the Isolyte S group had a lower chloride concentration (mEq/L: normal values 95 to 110; normal saline 130 +/- 9 vs. Isolyte S 117 +/- 7 [p < .02]) and a lower potassium concentration (mEq/L: normal values 3.5 to 5.0; normal saline 4.4 +/- 0.5 vs. Isolyte S 3.7 +/- 0.3 [p < .01]). There were no significant differences between normal saline or Isolyte S in the values of PCO2, lactic acid, sodium, total and ionized calcium, inorganic phosphorus, total protein, albumin, hemoglobin, and hematocrit. CONCLUSIONS: Fewer systemic acid-base and electrolyte derangements were observed when blood was washed with Isolyte S. Differences between the normal saline and Isolyte S groups are ascribed primarily to the constituents of the wash solution. We conclude that Isolyte S, a physiologic, balanced, multielectrolyte solution, should be considered as the wash solution in high-volume autologous cell saver blood processing and transfusion.

Animals↗

Acute moderate hyponatraemia and its rapid correction: effects on striatal and pontine ultrastructure in an animal model of the TURP syndrome.

BACKGROUND AND OBJECTIVE: To investigate the effects of moderate hyponatraemia, induced by intravenous application of an electrolyte-free irrigation fluid, as a model of the human transurethral prostate resection syndrome and of its rapid correction by hypertonic saline infusion in rats. METHODS: Experimental animals received irrigation fluid (Purisole SM) 20 mL kg(-1) body weight, intravenously. In one group, hyponatraemia was subsequently rapidly corrected by infusion of hypertonic saline (NaCl 5.85%), while rats of group two were 'sham-corrected' by infusion of a balanced salt crystalloid solution. Plasma sodium concentrations were analysed during and at the end of the experiments. After 10 days, experimental and untreated control animals were killed humanely, fixed by perfusion and the brains were prepared for electron microscopic investigation of myelin sheets and glial cell numbers in the striatum and pons. RESULTS: The myelin appearance was unaltered in experimental groups compared to controls, but glial cell numbers were distinctly altered in the pons but not in the striatum. In the pons, oligodendrocytes were significantly reduced in number upon rapid correction of hyponatraemia, while astrocyte numbers were increased in rats with uncorrected hyponatraemia. CONCLUSIONS: Our electron microscopic data demonstrate that the effects of hyponatraemia and of its rapid correction are multifarious in animals. This may also apply for human patients during transurethral prostate resection.

Animals↗

Inflammatory mediator removal by zero-balance ultrafiltration during cardiopulmonary bypass.

The abnormal conditions to which blood is subjected during cardiopulmonary bypass (CPB) trigger an activation of the inflammatory response in all patients to varying degrees. Both complement activation and the release of cytokines characterize this response. Most inflammatory mediators have a molecular weight that is below the membrane pore size of commonly used ultrafilters, which should allow them to be freely filtered. However, some mediators have been shown to fail to cross through the membrane even though they are small enough to cross. The purpose of the present study was to determine whether certain inflammatory mediators could be removed by ultrafiltration when performed during the rewarming phase of CPB. Thirty adult patients undergoing a single, open-heart procedure were randomized to either control (no ultrafiltration) or to the zero-balance ultrafiltration (ZBUF) group. ZBUF was performed by removing 3 l/m2 blood using a 65-kDa ultrafilter with 1.3-m2 surface area. A volume of a balanced salt crystalloid solution (Plasmalyte) equal to the filtered blood volume was given to replace the fluid removed. Patient data was taken before CPB (T1), immediately following CPB (T2), and 12 h following the procedure (T3). The average volume of filtrate removed during ZBUF was 6405 ml, which was analyzed for the presence of interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF-alpha), C3a, and C5a. The average concentrations of the mediators measured in the effluent were: IL-1, 0.17 pg/ml; IL-6, 0.64 pg/ml; TNF-alpha, 1.25 ng/ml; C3a, 782.6 ng/ml; C5a, 25.6 ng/ml. In every case except for IL-1, the amounts of mediators removed were significantly greater than zero. This study demonstrates that ultrafiltration is a strategy that can be used during CPB in the adult to remove significant amounts of inflammatory mediators.

Adult↗

Cardiac surgical conditions induced by beta-blockade: effect on myocardial fluid balance.

BACKGROUND: Both crystalloid and blood cardioplegia result in cardiac dysfunction associated with myocardial edema. This edema is partially due to the lack of myocardial contraction during cardioplegia, which stops myocardial lymph flow. As an alternative, acceptable surgical conditions have been created in patients undergoing coronary artery bypass operations with esmolol-induced minimal myocardial contraction. We hypothesized that minimal myocardial contraction during circulatory support using either standard cardiopulmonary bypass (CPB) or a biventricular assist device would prevent myocardial edema by maintaining cardiac lymphatic function and thus prevent cardiac dysfunction. METHODS: We placed 6 dogs on CPB and 6 dogs on a biventricular assist device and serially measured myocardial lymph flow rate and myocardial water content in both groups and preload recruitable stroke work only in the CPB dogs. In all dogs we minimized heart rate with esmolol for 1 hour during total circulatory support. RESULTS: Although myocardial lymph flow remained at baseline level during CPB and increased during biventricular assistance, myocardial water accumulation still occurred during circulatory support. However, as edema resolved rapidly after separation from circulatory support, myocardial water content was only slightly increased after CPB and biventricular assistance, and preload recruitable stroke work was normal. CONCLUSIONS: Our data suggest that minimal myocardial contraction during both CPB and biventricular assistance supports myocardial lymphatic function, resulting in minimal myocardial edema formation associated with normal left ventricular performance after circulatory support. The concept of minimal myocardial contraction may be a useful alternative for myocardial protection, especially in high-risk patients with compromised left ventricular function.

Adrenergic beta-Antagonists↗

Intraoperative endogenous erythropoietin levels and changes in intravascular blood volume in healthy humans.

There is accumulating evidence of a relationship between changes in intravascular blood volume and endogenous erythropoietin (EPO) levels. In this study, eight healthy adult American Society of Anesthesiologists class-I patients due for prolonged elective surgery were randomised either to preoperative hypervolaemic haemodilution using hydroxyethyl starch, followed by intraoperative crystalloid infusion, or to standard intraoperative normovolaemic fluid balance management using crystalloids (control group). Electrolytes, creatinine, urea, osmolality, urine output and blood gases were monitored pre- and intraoperatively for 6 h, Comparable cardiopulmonary and renal homeostasis were maintained in both groups. We found that central venous pressure increased and EPO levels decreased, both significantly, in the hypervolaemic haemodilution group relative to controls. There were no significant intergroup changes in any other parameters. By controlling for other known determinants of EPO levels, our data indicate a relationship between EPO levels and changes in intravascular blood volume in humans, supporting the notion of EPO as a volume-regulated, and possibly volume-regulating, hormone.

Adult↗

Dilutional re-expansion with crystalloid after massive hemorrahage: saline versus balanced electrolyte solution for maintenance of normal blood volume and arterial pH.

When administered in sufficient amounts, normal saline and Lactated Ringer's Solution are equally effective in maintaining adequate circulatory volumes despite severe blood loss and resultant hypoproteinemia. Arterial pH is maintained within normal limits when either solution is used for resuscitation provided the circulatory volume has been re-expanded to adequate levels for good tissue perfusion and support of aerobic metabolism. The pH of the infused solutions has no effect on blood pH under these circumstances. Fourteen splenectomized dogs were subjected to continuous hemorrhage and simultaneous replacement with either normal saline or Lactated Ringer's Solution. The cumulative replacement volume ratio necessary for equilibration after 61% RBC depletion was 7:1 crystalloid to the whole "undiluted" blood shed, in both groups. Indicators of pulmonary-circulatory physiology remained stable within normal limits. Arterial pH did not exhibit significant changes from normal values after resuscitation with NS or LRS. The group infused with LRS exhibited no change in arterial pH, 7.40 plus or minus .07 initial and 7.40 plus or minus .09 final; in the group with NS replacement a slight decrease from control was noted, 7.40 plus or minus .07 initial and 7.36 plus or minus .06 final. These differences, however, are not statistically significant. Of the 14 subjects, 13 were long-term survivors. The one death was associated with a technical mishap shortly after completion of the experiment. Because banked blood imposes a "net" alkaline metabolic load (sodium citrate), patients expected to be transfused with large volumes of stored blood might be better resuscited with normal salin than with Ringer's Lactate Soultions, to minimize or avert the otherwise resultant metabolic alkalosis.

Animals↗

Albumin versus crystalloid prime solution for cardiopulmonary bypass in young children.

OBJECTIVE: To determine the effects of adding 5% albumin to the cardiopulmonary bypass prime on perioperative fluid status and fluid management in young children. DESIGN: Prospective randomized study. SETTING: Single university hospital. PATIENTS: Pediatric patients of <14 kg undergoing cardiac surgery requiring cardiopulmonary bypass. INTERVENTIONS: Patients received a 5% albumin prime or a crystalloid prime. Perioperative fluid intake, output, and daily weights were recorded. Serial hematocrits, colloid osmotic pressures, and serum albumins were measured. Outcomes and complications were documented. MEASUREMENTS AND MAIN RESULTS: There were 86 patients aged 3 days to 4 yrs; 44 patients had an albumin prime and 42 had a crystalloid prime. Patients in the albumin group had a net negative fluid balance at the end of cardiopulmonary bypass compared with a net positive fluid balance in the crystalloid group. Patients in the albumin group had significantly higher serum albumins and colloid osmotic pressures and gained less weight postoperatively. However, their hematocrits were lower, and more patients in the albumin group received packed red blood cells. By 24 hrs postoperatively, there were no differences in colloid osmotic pressures and hematocrits between groups, and by the fourth postoperative day, there was no difference in weight gain. No differences were found in length of mechanical ventilation, intensive care unit or hospital stay, complications, or mortality. CONCLUSIONS: Albumin in the prime may attenuate the extravasation of fluid out of the vascular space, but it may be associated with an increased transfusion rate. The risk/benefit ratio for this intervention warrants further study.

Albumins↗

Fluid balance in ANTU-injured lungs during crystalloid and colloid infusions.

A controversy exists as to the preferred solution for plasma volume replacement and cardiac output maintenance in the presence of lung injury. To evaluate these responses, crystalloid and colloid infusions were compared in dogs treated with 5 mg/kg of alpha-naphthylthiourea (ANTU), which produces a predictable increase in vascular permeability and extravascular water (QW) in the lung. A tracheobronchial lymphatic from the left lung was cannulated and left atrial (Pla) pressure, lymph flow, lymph-to-plasma protein concentration ratios, and thermal dilution cardiac output were monitored. Test infusions were either 15 ml/kg of 6% dextran 70 (DX) or 60 ml/kg of normal saline (NS) infused over 20 min. Solutions were infused 3 h after ANTU as follows: group I (DX); group II (NS), group III (DX, constant Pla); and group IV (NS, constant Pla). In groups III and IV, Pla was maintained constant by bleeding into a reservoir during an exchange transfusion. Postinfusion QW increased to 9.01 and 9.14 g/g blood-free dry wt for groups I and II, respectively, but there was no significant postinfusion increase in QW for groups III and IV compared with the 3-h preinfusion values. However, cardiac output was significantly higher at 5 h in group III compared with group IV. These studies indicate that capillary hydrostatic pressure was the major determinant of QW during the infusions but that DX maintained cardiac output significantly higher because of vascular retention of the colloids.

Animals↗

Ovarian hyperstimulation syndrome in novel reproductive technologies: prevention and treatment.

OBJECTIVE: To overview the world literature on ovarian hyperstimulation syndrome (OHSS) and modes of prevention and treatment of OHSS. STUDY SELECTION: All the pertinent literature on OHSS, its prevention, and strategies for treatment were reviewed. PREVENTION: Key to prevention is proper identification of the population at risk, which includes women with either the hormonal or the morphological signs of polycystic ovarian disease, high serum estradiol (E2) before human chorionic gonadotropin (hCG) administration (E2 greater than 4,000 pg/mL), multiple follicular response (greater than 35), younger age, and lean habitus. When a high risk situation is recognized, ovulatory dose of hCG may be reduced, avoided (with cycle cancellation), or substituted by gonadotropin-releasing hormone or its agonist. Luteal support with hCG is to be bypassed. To minimize risk of OHSS, endogenous pregnancy-drived hCG may be eluded by judicious cryopreservation of all embryos. Last, follicular aspiration will allow higher levels of E2 and larger number of follicles to be matured with lesser risk of OHSS than conventional ovulation induction without follicular aspiration. TREATMENT: In-house for the severe and intensive care for the critical form. Meticulous fluid and electrolyte balance using both crystalloids and colloids (albumin) until hemoconcentration abates. Paracentesis is indicated for tight ascites, deteriorating kidney functions, and symptomatic relief. Diuretics may be prudently used once hemodilution is achieved. Dopamine drip may be used as a renal rescue, whereas heparin is indicated for thromboembolic phenomena and surgery reserved for abdominal catastrophies. Therapeutic interruption of an early gestation may be lifesaving when all other measures have failed. CONCLUSIONS: Although severe and critical OHSS may not be completely avoided, early recognition of high-risk factors, judicious prevention schemes, and treatment strategies should reduce the complication and long-term sequelae of this iatrogenic syndrome.

Chorionic Gonadotropin↗

Influence of volume replacement with colloids versus crystalloids in neonates on venoarterial extracorporeal membrane oxygenation on fluid retention, fluid balance, and ECMO runtime.

In this retrospective study, we compared the effects of colloid versus crystalloid fluid replacement on the clinical signs of capillary leakage syndrome in 30 neonates with pulmonary hypertension due to meconium aspiration syndrome on venoarterial membrane oxygenation (VA-ECMO). Before 2000, 15 neonates received volume replacement with a pasteurized plasma protein solution (3.8% albumin); after 2000, 15 neonates received normal saline. Patient characteristics and pre-ECMO values did not differ between the two groups. Total fluid balance was also equal. Diuretic use was significantly higher in the colloid group (p < 0.001). The chest wall soft-tissue index was significantly higher in the crystalloid group (p < 0.005), as were the ventilator settings at the end of the ECMO runtime (p < 0.05). Serum colloid osmotic pressure, albumin, urea nitrogen, and creatinine were significantly higher in the colloid group (p < 0.0001, < 0.0001, < 0.001, and < 0.05, respectively). Duration of VA-ECMO, of artificial ventilation after ECMO treatment, and the mortality rate did not differ between the two groups. We conclude that volume replacement with crystalloids in neonates on VA-ECMO aggravated the edema in a preexisting situation of capillary leakage syndrome, whereas volume replacement with colloids could impair the kidney function.

Capillary Leak Syndrome↗

Long-term observation following traumatic-hemorrhagic shock in the dog: a comparison of crystalloidal vs. colloidal fluids.

The effect of volume replacement with crystalloidal and colloidal solutions was analyzed in 40 anesthetized Foxhounds subjected to a standardized traumatic-hemorrhagic shock. Following trauma and hypotension (MAP 40 mmHg; 3.0 +/- 0.5 hr) the animals were randomized to treatment with autologous blood and hydroxyethyl starch 6% (HES 450/0.7), or human serum albumin 5% (ALB), dextran-60 6% (DX), Ringer's lactate (RL), and hyperosmolar saline 1.3% (HS), respectively. While analgesia and sedation were maintained, the hemodynamic measurements were continued for a 24-hr period. Crystalloids and colloids were found equally effective in maintaining the macrohemodynamics following resuscitation from traumatic-hemorrhagic shock. To keep central hemodynamics at pre-shock level required at least four times higher volumes of crystalloids than colloids. No specific advantage for one of the substitutes tested was found with regard to accumulation of water in the lung during the first 24 hr following shock in dogs. Extravascular lung water (thermo-dye) and organ water (gravimetry) were not different between the groups. However, fluid loss into the abdominal cavity as well as albumin extravasation into lung interstitium and abdominal cavity were more pronounced in the crystalloid-treated animals, whereas albumin redelivery by the lymph was decreased. The deterioration of tissue oxygen extractions as well as the changes in acid-base balance in both crystalloid-treated groups reflect the persistent microcirculatory inhomogeneity in spite of normal macrohemodynamics.

Acid-Base Equilibrium↗

Novel resuscitation strategy for pulmonary contusion after severe chest trauma.

BACKGROUND: Adenosine A2a receptor stimulation can increase coronary perfusion and also reduce leukocyte-mediated inflammatory responses in some conditions. Hextend is a novel colloid solution that may have antioxidant properties. All these actions might be beneficial after severe chest trauma, but have never been investigated. To fill these gaps, this study evaluated the therapeutic potential of a novel adenosine A2a agonist during fluid resuscitation from severe chest trauma with either standard-of-care crystalloid or Hextend. METHODS: Anesthetized, ventilated swine received unilateral, blunt trauma to the right chest via captive bolt gun, followed by a 10- to 12-mL/kg arterial hemorrhage. After 25 minutes of shock, ATL-146e was started (10 ng/kg/min intravenously for 180 minutes). After an additional 5 minutes, the minimum amount of either colloid (Hextend, 5% hetastarch in lactate-buffered, balanced electrolyte solution) or crystalloid (lactated Ringer's [LR] solution) was administered to maintain mean arterial pressure > 70 mm Hg and heart rate < 100 beats/min and to correct lactate for 180 minutes postinjury. Cardiopulmonary function was monitored and serial bronchoalveolar lavage samples were analyzed for protein, leukocyte infiltration, and expression of cyclooxygenase (COX)-1 and COX-2 isozymes as markers of the inflammatory cascade. RESULTS: Fluid requirements were reduced by half with Hextend compared with LR (p < 0.05). ATL-146e in either Hextend or LR transiently increased cardiac output, cardiac contractility, and systemic oxygen delivery (all p < 0.05). Pao(2)/Fio(2) ratio was 50 to 100 higher and bronchoalveolar lavage leukocytes were reduced by half with Hextend versus LR (both p < 0.05), but there was no added effect of ATL-146e. COX-1 expression was induced in macrophages (Mphis), whereas COX-2 was induced in neutrophils. Neither Hextend nor ATL-146e reduced COX expression. CONCLUSION: Hextend reduced the volume for initial resuscitation, which may offer logistical advantages in prehospital field conditions or whenever there is limited medical resources or prolonged transport times; ATL-146e improved early cardiac performance without causing hypotension or bradycardia; when administered 25 to 30 minutes after injury, neither Hextend nor ATL-146e altered inflammatory changes in pulmonary Mphis or infiltrating PMNs; and further studies are needed to determine whether these short-term benefits correlate with long-term outcome.

Animals↗

Crystalloid versus colloid resuscitation in experimental hemorrhagic pancreatitis.

In a canine model of acute hemorrhagic pancreatitis, crystalloid resuscitation with a balanced salt solution adequately restored plasma volume, supported tissue perfusion and prevented excessive hemodilution without detrimental effects on pulmonary pressures or oxygenation. No advantages in using colloid resuscitation were apparent in our study.

Acute Disease↗

Acute plasmapheresis during cardiac surgery: volume replacement by crystalloids versus colloids.

Acute plasmapheresis (APP) is an additional tool for blood conservation during cardiac surgery. In a randomized study of 60 aortocoronary bypass patients undergoing APP, the influence of replacement of the withdrawn autologous plasma (10 mL/kg) by either colloids (low molecular weight hydroxyethyl starch solution [6% HES 200/0.5]) or crystalloids (Ringer's solution) was investigated. APP was performed by means of a centrifugation technique producing platelet-poor plasma. During and after cardiopulmonary bypass (CPB), either a cell saver (CS) or a hemofiltration (HF) device was also used for blood concentration. Almost three times as much crystalloid as HES solution was necessary for replacement of autologous plasma. Fluid balance during CPB was significantly more positive in the crystalloid patients, particularly when a CS was used. Blood loss was highest in the crystalloid patients in whom a CS was used in addition to APP, and these were the only patients who needed packed red cells. The platelet count, AT-III and fibrinogen plasma concentrations, colloid osmotic pressure, albumin, and total protein were significantly less compromised in the patients with colloid volume replacement. These parameters were closest to control values in patients receiving colloid replacement and HF. It is concluded that colloid is preferred for replacement of autologous plasma withdrawn by APP, and HF is superior to the CS when the combined technique for blood conservation is used.

Coronary Artery Bypass↗

Gastric intramucosal pH changes after volume replacement with hydroxyethyl starch or crystalloid in patients undergoing elective abdominal aortic aneurysm repair.

PURPOSE: Gastric intramucosal pH (pHi), a surrogate marker of tissue oxygenation, falls following abdominal aorta aneurysm (AAA) repair. We tested the hypothesis that volume replacement with a hydroxyethyl starch solution would result in better preserved splanchnic oxygenation than would volume replacement with crystalloid solutions. MATERIALS AND METHODS: This was a prospective, randomized, nonblinded study set in a university-affiliated community hospital. Thirty patients undergoing elective AAA repair were studied. Patients were randomly selected to receive intraoperative and postoperative fluid replacement with either hetastarch or crystalloid. According to the study protocol, patients could not receive in excess of 3,000 mL of hetastarch. Tissue oxygenation was assessed indirectly by measuring pHi using a nasogastric tonometer. Hemodynamic, oxygenation, and pHi data were collected preoperatively, preclamp, before unclamping, at the end of the procedure and postoperatively for 24 hours. Coagulation parameters were determined preoperatively and postoperatively for 24 hours. RESULTS: Fifteen patients were randomized to each group. There were 18 male and 12 female patients, whose mean age was 66 +/- 9 years. The intraoperative fluid balance was significantly greater in the crystalloid compared with the hetastarch group (4,194 +/- 1,500 mL v 2,949 +/- 1,123 mL; P = .05, 95% confidence interval [C] 23 to 2,519 mL). There were no significant differences in the amount of intraoperative blood loss or postoperative transfusion requirements between the two groups. The difference between the preoperative pHi and nadir was 0.07 +/- 0.03 in the hetastarch group compared with 0.13 +/- 0.04 in the crystalloid group (P = .001, Cl 0.03 to 0.09). By multivariate analysis the only variable that influenced the fall in pHi was the type of resuscitation fluid (F ratio of 7.63; P = .01). There were no significant differences in hemodynamic- and oxygenation-derived variables or coagulation parameters between the two groups of patients. The length of mechanical ventilation, intensive care unit, and hospital stay was comparable between the two groups of patients. CONCLUSION: In patients undergoing major surgery, volume resuscitation with hydroxyethyl starch solutions may improve microvascular blood flow and tissue oxygenation.

Aged↗