DO PLASMA SUBSTITUTES HAVE ADDITIONAL PROPERTIES BEYOND CORRECTING VOLUME DEFICITS?

Fluid therapy in organ transplantation

PURPOSE OF REVIEW

Fluid management remains a controversial subject in perioperative medicine and organ transplantation. Various case series, anecdotes and tradition guide many fluid choices, especially when good evidence is lacking. Recent advances in the understanding of pharmacokinetic and pharmodynamic profiles of fluids, as well as transplantation physiology and pathophysiology, can guide us in new approaches to common problems.

RECENT FINDINGS

This review is intended to describe some of the latest thinking on subjects like saline-induced hyperchloraemic metabolic acidosis, the use of goal-directed approaches to volume resuscitation in perioperative medicine, the relative lack of evidence for low central venous pressure techniques in liver transplantation, some of the drug effects of intravenous fluids, as well as the complex issue of different crystalloids and colloids in renal transplantation.

SUMMARY

Fluid therapy in transplant medicine is usually best practiced using goal-directed approaches and balanced electrolyte formulations when possible, even in renal failure. Some fluids may exert drug effects that could alter organ preservation and reperfusion, while the certain hydroxyethyl starches appear to be less toxic in renal transplantation than first suspected, especially when clinicians consider free water requirements in these settings.

Hypertonic Saline Dextran Ameliorates Organ Damage in Beagle Hemorrhagic Shock

OBJECTIVE

The goal of this study was to investigate the effect of hypertonic saline with 6% Dextran-70 (HSD) resuscitation on organ damage and the resuscitation efficiency of the combination of HSD and lactated ringers (LR) in a model of hemorrhage shock in dogs.

METHODS

Beagles were bled to hold their mean arterial pressure (MAP) at 50 ± 5 mmHg for 1 h. After hemorrhage, beagles were divided into three groups (n = 7) to receive pre-hospital resuscitation for 1 h (R1): HSD (4 ml/kg), LR (40 ml/kg), and HSD+LR (a combination of 4 ml/kg HSD and 40 ml/kg LR). Next, LR was transfused into all groups as in-hospital resuscitation (R2). After two hours of observation (R3), autologous blood was transfused. Hemodynamic responses and systemic oxygenation were measured at predetermined phases. Three days after resuscitation, the animals were sacrificed and tissues including kidney, lung, liver and intestinal were obtained for pathological analysis.

RESULTS

Although the initial resuscitation with HSD was shown to be faster than LR with regard to an ascending MAP, the HSD group showed a similar hemodynamic performance compared to the LR group throughout the experiment. Compared with the LR group, the systemic oxygenation performance in the HSD group was similar but showed a lower venous-to-arterial CO2 gradient (Pv-aCO2) at R3 (p < 0.05). Additionally, the histology score of the kidneys, lungs and liver were significantly lower in the HSD group than in the LR group (p < 0.05). The HSD+LR group showed a superior hemodynamic response but higher extravascular lung water (EVLW) and lower arterial oxygen tension (PaO2) than the other groups (p < 0.05). The HSD+LR group showed a marginally improved systemic oxygenation performance and lower histology score than other groups.

CONCLUSIONS

Resuscitation after hemorrhagic shock with a bolus of HSD showed a similar hemodynamic response compared with LR at ten times the volume of HSD, but HSD showed superior efficacy in organ protection. Our findings suggest that resuscitation with the combination of HSD and LR in the pre-hospital setting is an effective treatment.

Critical care considerations in the management of the trauma patient following initial resuscitation

Background

Care of the polytrauma patient does not end in the operating room or resuscitation bay. The patient presenting to the intensive care unit following initial resuscitation and damage control surgery may be far from stable with ongoing hemorrhage, resuscitation needs, and injuries still requiring definitive repair. The intensive care physician must understand the respiratory, cardiovascular, metabolic, and immunologic consequences of trauma resuscitation and massive transfusion in order to evaluate and adjust the ongoing resuscitative needs of the patient and address potential complications. In this review, we address ongoing resuscitation in the intensive care unit along with potential complications in the trauma patient after initial resuscitation. Complications such as abdominal compartment syndrome, transfusion related patterns of acute lung injury and metabolic consequences subsequent to post-trauma resuscitation are presented.

Methods

A non-systematic literature search was conducted using PubMed and the Cochrane Database of Systematic Reviews up to May 2012.

Results and conclusion

Polytrauma patients with severe shock from hemorrhage and massive tissue injury present major challenges for management and resuscitation in the intensive care setting. Many of the current recommendations for “damage control resuscitation” including the use of fixed ratios in the treatment of trauma induced coagulopathy remain controversial. A lack of large, randomized, controlled trials leaves most recommendations at the level of consensus, expert opinion. Ongoing trials and improvements in monitoring and resuscitation technologies will further influence how we manage these complex and challenging patients.

Polyvalent immunoglobulin significantly attenuated the formation of IL-1β in Escherichia coli-induced sepsis in pigs

Evidence suggests that adjunctive treatment with intravenous immunoglobulin preparations enriched with IgA and IgM reduce mortality in sepsis. The mode of action of polyvalent immunoglobulin is complex, including neutralization of toxins and modulation of complement activation and cytokine formation toward an anti-inflammatory profile. In this study we explored the effect of Pentaglobin, containing IgG, IgA and IgM, on the initial inflammatory reaction as well as on hemodynamics, using a well characterized and standardized porcine model of sepsis. Anesthetized and mechanically ventilated pigs, mean weight 14.9 kg, were allocated into two groups of 8 animals, receiving either Pentaglobin or saline, before sepsis was induced by intravenous Escherichia coli infusion. Five negative controls received saline only. All animals were observed for 4 h under extensive invasive monitoring. Pentaglobin significantly (p < 0.05) attenuated IL-1β formation by 38% at the end of the experiment, and markedly increased (p < 0.05) the formation of IL-10 at 60 min. TNF-α, IL-6, IL-8 and expression of the cell surface marker wCD11R3 were lower in the Pentaglobin group, but the differences were not significant. The serum concentration of LPS was three times higher in the Pentaglobin group (p < 0.005), indicating binding of LPS to Pentaglobin. Complementary in vitro experiments showed a higher binding affinity for IgM and IgA to LPS than for IgG. LPS-induced formation of IL-6 was significantly (p < 0.05) attenuated by Pentaglobin in an in vitro whole blood model. In conclusion, Pentaglobin decreased the key inflammasome IL-1β molecule in an E. coli-model of pigs sepsis.

Systematic analysis of hydroxyethyl starch (HES) reviews: proliferation of low-quality reviews overwhelms the results of well-performed meta-analyses

PURPOSE

Hydroxyethyl starch (HES) is a synthetic colloid used widely for resuscitation despite the availability of safer, less costly fluids. Numerous HES reviews have been published that may have influenced clinicians' practice. We have therefore examined the relationship between the methodological quality of published HES reviews, authors' potential conflicts of interest (pCOI) and the recommendations made.

METHODS

Systematic analysis of reviews on HES use.

RESULTS

Between 1975 and 2010, 165 reviews were published containing recommendations for or against HES use. From the 1990s onwards, favorable reviews increased from two to eight per year and HES's share of the artificial colloid market tripled from 20 to 60 %. Only 7 % (12/165) of these reviews of HES use contained meta-analyses; these 7 % had higher Overview Quality Assessment Questionnaire (OQAQ) scores [median (range) 6.5 (3-7)] than reviews without meta-analysis [2 (1-4); p < 0.001]. The rates of recommending against HES use are 83 % (10/12) in meta-analyses and 20 % (31/153) in reviews without meta-analysis (p < 0.0001). Fourteen authors published the majority (70/124) of positive reviews, and ten of these 14 had or have since developed a pCOI with various manufacturers of HES.

CONCLUSIONS

Low-quality HES reviews reached different conclusions than high-quality meta-analyses from independent entities, such as Cochrane Reviews. The majority of these low-quality positive HES reviews were written by a small group of authors, most of whom had or have since established ties to industry. The proliferation of positive HES reviews has been associated with increased utilization of an expensive therapy despite the lack of evidence for meaningful clinical benefit and increased risks. Clinicians need to be more informed that marketing efforts are potentially influencing scientific literature.

The impact of fluid therapy on microcirculation and tissue oxygenation in hypovolemic patients: a review

PURPOSE

An optimal volume replacement strategy aims to restore systemic hemodynamics with the ultimate goals of improving organ perfusion and microcirculation for sustaining adequate tissue oxygenation. This review presents the (patho)physiological basis of hypovolemia, microcirculation, and tissue oxygenation and presents a literature review on the effects of plasma substitutes on microperfusion and oxygenation in the clinical setting.

METHODS

Literature review of the effects of fluid therapy on microcirculation and tissue oxygenation using PubMed search including original papers in English from 1988 to 2009.

RESULTS

We identified a total of 14 articles dealing with the effects of different crystalloids and colloids on organ perfusion, microcirculation, and tissue oxygenation in patients. The results are divergent, but there is a general trend that colloids are superior to crystalloids in improving organ perfusion, microcirculation, and tissue oxygenation. Due to the limited number of studies and different study conditions, a meta-analysis on the effects of the volume replacement strategies on microcirculation is not possible.

CONCLUSIONS

Improving the microcirculation by volume replacement appears to be a promising issue when treating the critically ill. The growing insights from animal experiments have to be translated into the clinical setting to identify the optimal fluid regimen for correcting hypovolemia. New techniques for monitoring microcirculation at the bedside might provide such endpoints, although these have to be validated also in the clinical setting. Whether improved microperfusion and tissue oxygenation by fluid therapy will also improve patient outcomes will have to be proven by future studies.

Saline versus balanced hydroxyethyl starch: does it matter?

PURPOSE OF THE REVIEW

A total balanced volume replacement strategy is a new concept for correcting hypovolemia. To fulfill this concept, balanced colloids, for example, balanced hydroxyethyl starch (HES) solutions, are necessary in addition to balanced crystalloids. Conventional HES solutions consist of saline with abnormally high concentrations of sodium (154 mmol/l) and chloride (154 mmol/l).

RECENT FINDING

In animal as well as in human studies, the use of HES dissolved in a plasma-adapted solution showed beneficial effects on acid-base status compared with conventional HES dissolved in saline. As the base excess is an important surrogate marker for identifying patients with malperfused tissues, infusion of considerable amounts of unbalanced HES solutions producing low base excess would possibly result in inappropriate clinical interventions. Balancing the HES preparation was associated with significantly fewer alterations in coagulation; dilution of blood with balanced HES showed significantly fewer negative effects on thrombelastography and platelet aggregation than conventional HES.

SUMMARY

Although only a few studies using balanced HES solutions are available at present, it is difficult to argue against using HES preparations that are adapted to plasma instead of HES preparations that contain unphysiologic saline solution. First results are very promising - large clinical trials are necessary to assess the value of a total balanced volume replacement strategy including plasma-adapted HES solutions.

Comparison of the effects of gelatin and a modern hydroxyethyl starch solution on renal function and inflammatory response in elderly cardiac surgery patients

BACKGROUND

The effects of hydroxyethylstarch (HES) 130/0.4 6% and gelatin 4% on inflammation, endothelial integrity, and renal function after cardiac surgery were compared.

METHODS

Sixty patients aged >80 yr undergoing cardiac surgery were randomized to receive gelatin (n=30) or HES 130/0.4 (n=30). The colloid was used in the priming of the cardiopulmonary bypass circuit (500 ml) and for volume replacement until the second postoperative day (POD). Serum creatinine, creatinine clearance, IL-6, IL-10, intercellular adhesion molecule-1 (sICAM-1), urinary glutathione transferase-alpha, and neutrophil gelatinase-associated lipocalin (NGAL) were measured perioperatively. Serum creatinine was also reported approximately 60 days after discharge.

RESULTS

The mean(sd) volume of gelatin infused was 4180(440) ml, which was greater than the volume of HES infused 2910(330) ml (P=0.002). The mean(sd) volume of serum creatinine on the first POD was 151(24) micromol litre(-1) in the gelatin group and 126(13) micromol litre(-1) in the HES group (P=0.004). Values for the second POD were 161(0.26) and 133(16) micromol litre(-1), respectively (P=0.004). Creatinine clearance was lower in the gelatin group on the first POD [37(7) vs 46(8) ml min(-1) 1.73 m2 (P=0.004)] and the second POD [32(8) vs 45(10) ml min(-1) 1.73 m2 (P=0.002)]. Kidney function approximately 60 days after discharge did not differ between the groups. IL-6, IL-10, and sICAM-1 were significantly lower in the HES group than in the gelatin group on the first and second PODs. Urinary alpha-GST increased in both groups to a comparable extent. Urinary NGAL concentrations were higher in the gelatin than in the HES patients 5 h after surgery and on the first and second PODs.

CONCLUSIONS

In cardiac surgery patients aged >80 years, volume therapy with HES 130/0.4 6% was associated with less marked changes in kidney function and a less marked endothelial inflammatory response than gelatin 4%.

Tracheobronchiale Nekrose

Mediastinitis is a bacterial or non-bacterial infection of the mediastinum. Descending necrotizing mediastinitis (DNM) is a rare but life-threatening complication. The mostly feared form of mediastinitis very often has a fatal outcome. We report on a patient with tracheobronchial necrosis following DNM and emphasize the paramount importance of early and complex surgical therapy combined with immediate intensive care treatment. This case describes the intensive medicine and anaesthetic management, which was complicated by the tracheobronchial-pleural fistula and in particular by the respiratory therapy.

Pulmonary function is better preserved in pigs when acute normovolemic hemodilution is achieved with hydroxyethyl starch versus lactated Ringer's solution

Acute normovolemic hemodilution (ANH) has been proposed to decrease the need for allogenic blood transfusion. Consequently, great amounts of fluids are necessary to maintain hemodynamics during and after blood removal. The aim of this experiment was to evaluate the oxygenation, respiratory compliance, and lung structure during ANH performed with lactated Ringer's solution and hydroxyethyl starch (HES). Gas exchange, extravascular lung water, intrathoracic blood volume, serum osmolality, respiratory mechanics, and optical and electronic microscopy of lung biopsies were evaluated. Animals were randomized into three groups: CTL (control, n = 9), HES (HES 6% 200/0.5, n = 9), and LR (lactated Ringer's solution, n = 9). Animals in groups HES and LR underwent ANH to reach a preestablished hematocrit of around 15%. The removed blood was replaced with HES in a proportion of 1:1 and with lactated Ringer's solution 3:1. The LR group demonstrated a tendency for a marked time-dependence decrease in compliance (P = 0.013 in T2; P = 0.008 in T3) and in Pao2/fraction of inspired oxygen (Fio2) ratio (P = 0.033 in T2) as well as an increase in (A-a) Grad O2 (P = 0.037 in T2). Extravascular lung water and intrathoracic blood volume did not present any significant variation among the groups. In contrast, serum osmolality presented a significant decline in animals hemodiluted with lactated Ringer's solution. Optical and electronic microscopy of lungs biopsies revealed moderate to serious collapses and basement membrane enlargement in LR group. In this kind of experimental model, ANH with 6% HES (200/0.5) seems to preserve lung structure better as evidenced by maintenance of oxygenation indexes and respiratory compliance when compared with that in the Ringer's solution hemodiluted group.