Non-oncotic properties of albumin. A multidisciplinary vision about the implications for critically ill patients

INTRODUCTION

Effective resuscitation with human albumin solutions is achieved with less fluid than with crystalloid solutions. However, the role of albumin in today's critical care unit is also linked to its multiple pharmacological effects. Areas covered: The potential clinical benefits of albumin in select populations of critically ill patients like sepsis seem related to immunomodulatory and anti-inflammatory effects, antibiotic transportation and endothelial stabilization. Albumin transports many drugs used in critically ill patients. Such binding to albumin is frequently lessened in critically ill patients with hypoalbuminemia. These changes could result in sub-optimal treatment. Albumin has immunomodulatory capacity by binding several bacterial products. Albumin also influences vascular integrity, contributing to the maintenance of the normal capillary permeability. Moreover, the albumin molecule encompasses several antioxidant properties, thereby significantly reducing re-oxygenation injury, which is especially important in sepsis. In fact, most studies of albumin administration are a combination of a degree of resuscitation with a degree of maintenance or supplementation of albumin. Expert commentary: The potential clinical benefits of the use of albumin in selected critically ill patients such as sepsis seem related to its immunomodulatory and anti-inflammatory effects, antioxidant properties, antibiotic transportation and endothelial stabilization. Additional studies are warranted to further elucidate the underlying physiologic and molecular rationale.

Microvascular reactivity measured by vascular occlusion test is an independent predictor for postoperative bleeding in patients undergoing cardiac surgery

The purpose of the study is to investigate the relationship between microvascular reactivity and postoperative bleeding in cardiac surgery. The authors retrospectively analyzed a prospectively collected registry of cardiac surgery patients. Data from 154 patients enrolled in the registry were analyzed. A linear mixed model was performed to evaluate the association between the amount of postoperative chest tube output (CTO, milliliter, repeatedly measured at 0-8, 8-24, and 24-48 h) and tissue oxygen saturation (StO₂₎ recovery slope (%/s) measured by vascular occlusion test (VOT) at skin closure. A logistic regression was carried out to see the relationship between StO₂ recovery slope and packed red blood cell (PRBC) transfusion during the 48-h postoperative period. In the multivariable adjusted model, the effect of StO₂ recovery slope on postoperative CTO (log-transformed) was statistically significant, and the degree of StO₂ recovery slope was inversely related to the amount of CTO (exp(estimate) = 0.935; exp(95% CI) 0.881-0.992; p = 0.027). StO₂ recovery slope was also inversely associated with postoperative PRBC transfusion possibility (OR = 0.795; 95% CI 0.633-0.998; p = 0.048). Microvascular reactivity measured by VOT is independently and inversely associated with postoperative bleeding in patients undergoing cardiac surgery.

Safety of Recombinant Human Factor XIII in a Cynomolgus Monkey Model of Extracorporeal Blood Circulation

Factor XIII (FXIII) is a thrombin-activated plasma coagulation factor critical for blood clot stabilization and longevity. Administration of exogenous FXIII to replenish depleted stores after major surgery, including cardiopulmonary bypass, may reduce bleeding complications and transfusion requirements. Thus, a model of extracorporeal circulation (ECC) was developed in adult male cynomolgus monkeys ( Macaca fascicularis) to evaluate the nonclinical safety of recombinant human FXIII (rFXIII). The hematological and coagulation profile in study animals during and after 2 h of ECC was similar to that reported for humans during and after cardiopulmonary bypass, including observations of anemia, thrombocytopenia, and activation of coagulation and platelets. Intravenous slow bolus injection of 300 U/kg (2.1 mg/kg) or 1000 U/kg (7 mg/kg) rFXIII after 2 h of ECC was well tolerated in study animals, and was associated with a dose-dependent increase in FXIII activity. No clinically significant effects in respiration, ECG, heart rate, blood pressure, body temperature, clinical chemistry, hematology (including platelet counts), or indicators of thrombosis (thrombin:antithrombin complex and D-Dimer) or platelet activation (platelet factor 4 and beta-thromboglobulin) were related to rFXIII administration. Specific examination of brain, heart, lung, liver, and kidney from rFXIII-treated animals provided no evidence of histopathological alterations suggestive of subclinical hemorrhage or thrombosis. Taken as a whole, the results demonstrate the ECC model suitably replicated the clinical presentation reported for humans during and after cardiopulmonary bypass surgery, and do not suggest significant concerns regarding use of rFXIII in replacement therapy after extracorporeal circulation.

A Prospective Study of Outcomes, Healthcare Resource Utilization, and Costs Associated With Postoperative Nosocomial Infections

Objective.

We evaluated 4 important outcomes associated with postoperative nosocomial infection: costs, mortality, excess length of stay, and utilization of healthcare resources.

Design.

The outcomes for patients who underwent general, cardiothoracic, and neurosurgical operations were recorded during a previous clinical trial. Multivariable analyses including significant covariates were conducted to determine whether nosocomial infection significantly affected the outcomes.

Setting.

A large tertiary care medical center and an affiliated Veterans Affairs Medical Center.

Patients.

A total of 3,864 surgical patients.

Results.

The overall nosocomial infection rate was 11.3%. Important covariates included age, Karnofsky score, McCabe and Jackson classification of the severity of underlying disease, National Nosocomial Infection Surveillance system risk index, and number of comorbidities. After accounting for covariates, nosocomial infection was associated with increased postoperative length of stay, increased costs, increased hospital readmission rate, and increased use of antimicrobial agents in the outpatient setting. Nosocomial infection was not associated independently with a significantly increased risk of death in this surgical population.

Conclusion.

Postoperative nosocomial infection was associated with increased costs of care and with increased utilization of medical resources. To accurately assess the effects of nosocomial infections, one must take into account important covariates. Surgeons seeking to decrease the cost of care and resource utilization must identify ways to decrease the rate of postoperative nosocomial infection.

Estimating the Proportion of Healthcare-Associated Infections That Are Reasonably Preventable and the Related Mortality and Costs

Objective.

To estimate the proportion of healthcare-associated infections (HAIs) in US hospitals that are “reasonably preventable,” along with their related mortality and costs.

Methods.

To estimate preventability of catheter-associated bloodstream infections (CABSIs), catheter-associated urinary tract infections (CAUTIs), surgical site infections (SSIs), and ventilator-associated pneumonia (VAP), we used a federally sponsored systematic review of interventions to reduce HAIs. Ranges of preventability included the lowest and highest risk reductions reported by US studies of “moderate” to “good” quality published in the last 10 years. We used the most recently published national data to determine the annual incidence of HAIs and associated mortality. To estimate incremental cost of HAIs, we performed a systematic review, which included costs from studies in general US patient populations. To calculate ranges for the annual number of preventable infections and deaths and annual costs, we multiplied our infection, mortality, and cost figures with our ranges of preventability for each HAI.

Results.

AS many as 65%–70% of cases of CABSI and CAUTI and 55% of cases of VAP and SSI may be preventable with current evidence-based strategies. CAUTI may be the most preventable HAI. CABSI has the highest number of preventable deaths, followed by VAP. CABSI also has the highest cost impact; costs due to preventable cases of VAP, CAUTI, and SSI are likely less.

Conclusions.

Our findings suggest that 100% prevention of HAIs may not be attainable with current evidence-based prevention strategies; however, comprehensive implementation of such strategies could prevent hundreds of thousands of HAIs and save tens of thousands of lives and billions of dollars.

Transfusion strategy: impact of haemodynamics and the challenge of haemodilution

Blood transfusion is associated with increased morbidity and mortality and numerous reports have emphasised the need for reduction. Following this there is increased attention to the concept of patient blood management. However, bleeding is relatively common following cardiac surgery and is further enhanced by the continued antiplatelet therapy policy. Another important issue is that cardiopulmonary bypass leads to haemodilution and a potential blood loss. The basic role of blood is oxygen transport to the organs. The determining factors of oxygen delivery are cardiac output, haemoglobin, and saturation. If oxygen delivery/consumption is out of balance, the compensation mechanisms are simple, as a decrease in one factor results in an increase in one or two other factors. Patients with coexisting cardiac diseases may be of particular risk, but studies indicate that patients with coexisting cardiac diseases tolerate moderate anaemia and may even benefit from a restrictive transfusion regimen. Further it has been shown that patients with reduced left ventricular function are able to compensate with increased cardiac output in response to bleeding and haemodilution if normovolaemia is maintained. In conclusion the evidence supports that each institution establishes its own patient blood management strategy to both conserve blood products and maximise outcome.

Postoperative blood loss and transfusion associated with use of Hextend in cardiac surgery patients at a blood conservation center

BACKGROUND

Hydroxyethyl starch (HES) solutions are readily available colloids, but their widespread use is shadowed by controversies surrounding their effects on bleeding. This retrospective study was conducted to evaluate the relationship between Hextend (HEX; Hospira, Inc.) doses of 1 to 20 mL/kg and allogeneic transfusion and 24-hour chest tube drainage (CTD) in cardiac surgeries at a blood conservation center.

STUDY DESIGN AND METHODS

After institutional review board approval, data on 748 patients undergoing coronary artery bypass grafting (CABG), valve, or combined CABG and valve surgeries were collected. Cases not receiving HEX (due to contraindications, e.g., renal failure, bleeding diathesis) or receiving more than 20 mL per kg HEX, not accepting transfusions, or requiring more extensive surgery were excluded, and the remaining 621 cases were analyzed.

RESULTS

Overall transfusion rate and mean CTD were 12.7 percent and 460.4 mL, respectively. Patients who received transfusions received more HEX (10.8 mL/kg vs. 9.8 mL/kg; p = 0.043) but HEX per kg was not associated with higher transfusion rates in multivariate analysis (p = 0.077). HEX per kg was associated with CTD in both uni- and multivariate analyzes (p < 0.001) with 1.66 percent increase in CTD for every 1 mL per kg increase in HEX.

CONCLUSIONS

Although HEX was associated with transfusion in univariate analysis and with CTD in uni- and multivariate analysis, the former was no longer significant when adjusted for other predictors of transfusion in our selected patient population at a blood conservation center. The clinical significance of the observed increase in CTD remains undetermined. To minimize transfusion and bleeding in these patients, it is recommended that HEX be used in amounts of not more than 20 mL per kg together with point-of-care coagulation tests and other blood conservation strategies.

Recombinant Activated Factor VII: Treating Postoperative Hemorrhage in Cardiac Surgery

BACKGROUND

The purpose of this study is to review the effect of recombinant activated factor VII (rFVIIa) as rescue therapy in continuing severe postoperative hemorrhage, despite conventional measures in a series of cardiac patients at our institution.

METHODS

A series of all patients who received rFVIIa as rescue therapy for uncontrollable postoperative hemorrhage after cardiac surgery over a 2-year period was analyzed. We assessed and compared the use of blood products, coagulation indicators (international normalized ratio [INR], activated partial thromboplastin [APTT], and fibrinogen), and platelet levels immediately before and after the rFVIIa was given.

RESULTS

Twelve patients received rFVIIa. Eight patients (75%) had thoracic aortic surgery. Bleeding stopped in all cases. Prior to the administration of rFVIIa, mean blood product usage was the following: fresh frozen plasma (FFP) 18.7 units (range, 10-40); packed cells 7.7U (range, 0-18); cryoprecipitate 19.5U (range, 8-32); and platelets 22.5U (range, 10-40). The mean coagulation results immediately prior to rFVIIa were the following: INR 2.0 (range, 1.3-8.5); APTT 60 seconds (range, 30-220); fibrinogen 3.2 gm/L (range, 1.6-6.4), and platelet count was 174,000 (range, 78,000-257,000). After rFVIIa administration the mean blood product usage was the following: FFP 0U (range, 0-2); red cells 0U (range, 0-1); cryoprecipitate 0 (range, 0); and platelets 0 (range, 0); p less than 0.0005. The mean INR was 0.9 (range, 0.7-1.5), p less than 0.001; mean APTT was 42 seconds (range, 30-87), mean fibrinogen was 3.1 (range, 1.7-4.5), and the mean platelet count was 170,000 (range, 93,000-289,000); p values not significant. There were no thrombotic complications, no cardiac ischemic events, and no deaths.

CONCLUSIONS

Our results support the use of rFVIIa as rescue therapy in severe, uncontrollable, nonsurgical, postoperative hemorrhage after cardiac surgery as efficacious and safe.

Albumin administration--what is the evidence of clinical benefit? A systematic review of randomized controlled trials

BACKGROUND AND OBJECTIVE

The advantages of albumin over less costly alternative fluids continue to be debated. Meta-analyses focusing on survival have been inconclusive, and other clinically relevant end-points have not been systematically addressed. We sought to determine whether albumin confers significant clinical benefit in acute illness compared with other fluid regimens.

METHODS

Database searches (MEDLINE, EMBASE, Cochrane Library) and other methods were used to identify randomized controlled trials comparing albumin with crystalloid, artificial colloid, no albumin or lower-dose albumin. Major findings for all end-points were extracted and summarized. A quantitative meta-analysis was not attempted.

RESULTS

Seventy-nine randomized trials with a total of 4755 patients were included. No significant treatment effects were detectable in 20/79 (25%) trials. In cardiac surgery, albumin administration resulted in lower fluid requirements, higher colloid oncotic pressure, reduced pulmonary oedema with respiratory impairment and greater haemodilution compared with crystalloid and hydroxyethylstarch increased postoperative bleeding. In non-cardiac surgery, fluid requirements, and pulmonary and intestinal oedema were decreased by albumin compared with crystalloid. In hypoalbuminaemia, higher doses of albumin reduced morbidity. In ascites, albumin reduced haemodynamic derangements, morbidity and length of stay and improved survival after spontaneous bacterial peritonitis. In sepsis, albumin decreased pulmonary oedema and respiratory dysfunction compared with crystalloid, while hydroxyethylstarch induced abnormalities of haemostasis. Complications were lowered by albumin compared with crystalloid in burn patients. Albumin-containing therapeutic regimens improved outcomes after brain injury.

CONCLUSIONS

Albumin can bestow benefit in diverse clinical settings. Further trials are warranted to delineate optimal fluid regimens, in particular indications.

Hetastarch and Bleeding Complications After Coronary Artery Surgery

STUDY OBJECTIVES

Controversy persists concerning the potential association between intraoperative use of hetastarch (ie, hydroxyethyl starch [HES]) and postoperative bleeding in patients undergoing surgery. To determine whether intraoperative HES use is associated with an increased risk of postoperative bleeding following coronary artery bypass graft (CABG) surgery.

DESIGN

Case-control study.

SETTING

A large academic medical center in the northeastern United States.

PARTICIPANTS

A consecutive sample of 238 patients undergoing CABG surgery.

MAIN OUTCOME MEASURES

Cases consisted of patients who had received either > or = 3 U packed RBCs, > or = 3 U platelets, > or= 3 U fresh frozen plasma, or any cryoprecipitate within 72 h after undergoing a CABG procedure, or who had undergone surgical revision for bleeding. All other CABG surgery patients served as control subjects.

RESULTS

In multivariate models that controlled for a wide variety of demographic and clinical characteristics, we found that, compared to patients who did not receive any HES during surgery, those who received 1 U intraoperative HES had more than twice the risk of a bleeding outcome (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.10 to 4.91), and those who received 2 or 3 U HES had more than four times the risk of postoperative bleeding (OR, 4.57; 95% CI, 1.74 to 12.00).

CONCLUSIONS

HES use in patients undergoing CABG surgery may be associated with a significant risk of postoperative bleeding. A double-blinded, randomized, controlled trial will be necessary to confirm this finding.

Chronic kidney disease as a risk factor for bleeding complications after coronary artery bypass surgery

BACKGROUND

The aim of the study is to define the role of chronic kidney disease (CKD) as a risk factor for postoperative bleeding in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

This is a retrospective cohort study of 238 consecutive patients who underwent isolated CABG surgery. Patients were followed up for the event of a significant bleed, defined as administration of either three or greater units of packed red blood cells, three or greater units of platelets, three or greater units of fresh frozen plasma, or any cryoprecipitate within 72 hours after a CABG procedure or undergoing a surgical revision for bleeding. Glomerular filtration rate (GFR) at baseline was calculated using the Cockroft-Gault formula. A final multiple logistic regression model was selected from a large set of presurgical and intraoperative covariates by using backward elimination (P > 0.20).

RESULTS

After controlling for age, sex, elective versus emergent surgery, intraoperative activated clotting time, serum albumin level, extracorporeal bypass time, and baseline hematocrit, we found that even mild levels of renal impairment were associated with increased risk for postoperative bleeding: patients with a GFR of 40 mL/min or less had six times the odds of postoperative bleeding than patients with a GFR greater than 100 mL/min (odds ratio [OR], 6.51; 95% confidence interval [CI], 1.87 to 22.66); those with a GFR of 41 to 60 mL/min had nearly four times the risk (OR, 3.87; 95% CI, 1.21 to 12.35). Even patients with mild CKD at a GFR of 61 to 80 mL/min were at an elevated risk (OR, 2.11); however, the 95% CI of 0.79 to 5.64 included the null value. Similar results were found when using the cruder Kidney Disease Outcomes Quality Initiative classification of CKD.

CONCLUSION

CKD is associated with risk for postoperative bleeding in patients undergoing CABG surgery, not only at more advanced stages, but probably at relatively mild levels of renal impairment, as well.

Hemorrhage after coronary artery bypass graft procedures

OBJECTIVES

To identify risk factors for excessive bleeding after coronary artery bypass graft (CABG) procedures and to quantify the outcomes related to this complication.

DESIGN

We conducted a case-control study to identify risk factors for hemorrhage following CABG surgery and a historical cohort study to quantify outcomes of hemorrhage.

SETTING

The cardiothoracic surgery service of a university hospital.

RESULTS

Factors associated with excessive blood loss were recent catheterization (odds ratio [OR] = 0.44; 95% confidence interval [CI95], 0.21 to 0.91); age older than 65 years (OR = 1.94; CI95, 0.96 to 3.93); bypass time of 150 minutes or more (OR = 2.91; CI95, 1.09 to 7.81); and postoperative platelet count of 160,000/mm3 or less (OR = 2.36; CI95, 1.06 to 5.22). The attributable cost of a postoperative hemorrhage was $3,866 (P = .0002) overall, $9,912 (P = .0001) for patients who required reoperation, and $3,316 (P = .03) for those treated medically. The median attributable postoperative length of stay was 1 day longer for cases than for controls (P = .011). Postoperatively, patients who hemorrhaged received significantly larger volumes of packed red blood cells (P < .0001), fresh frozen plasma (P < .0001), platelets (P < .0001), plasminate (P = .007), protamine sulfate (P < .0001), desmopressin acetate (P < .0001), and epsilon-aminocaproic acid (P < .0001) than did controls.

CONCLUSIONS

Age, duration of bypass, and postoperative platelet count were associated with excessive bleeding. Hemorrhage after CABG surgery significantly increased the length of stay and cost of care.

Albumin versus hydroxyethyl starch in cardiopulmonary bypass surgery: a meta-analysis of postoperative bleeding

BACKGROUND

This meta-analysis tested the hypothesis that cumulative blood loss during the first 24 hours after cardiopulmonary bypass is lower in patients exposed to albumin than hydroxyethyl starch (HES).

METHODS

Randomized controlled trials comparing albumin and HES in cardiopulmonary bypass patients were identified by bibliographic database searches and other methods.

RESULTS

Sixteen trials involving 653 randomized patients were included. In 88% of randomized comparisons, postoperative bleeding was lower in the albumin group, and the standardized mean difference in bleeding favoring albumin across all trials (-0.24; 95% confidence interval, -0.40 to -0.08) was statistically significant. Bleeding differences between albumin and either high or medium molecular weight HES were similar. In trials of adults, the pooled mean blood loss in the albumin group was 693+/-350 mL compared with 789+/-487 mL in the HES group. The estimated proportion of adult albumin group patients with blood loss of more than 1,000 mL was 19% compared with 33% of adult HES group patients. Conclusions. Postoperative blood loss is significantly lower in cardiopulmonary bypass patients exposed to albumin than HES.