[Small volume--large benefits?]

Small-volume resuscitation with hyperoncotic albumin: a systematic review of randomized clinical trials

Background

Small-volume resuscitation can rapidly correct hypovolemia. Hyperoncotic albumin solutions, long in clinical use, are suitable for small-volume resuscitation; however, their clinical benefits remain uncertain.

Methods

Randomized clinical trials comparing hyperoncotic albumin with a control regimen for volume expansion were sought by multiple methods, including computer searches of bibliographic databases, perusal of reference lists, and manual searching. Major findings were qualitatively summarized. In addition, a quantitative meta-analysis was performed on available survival data.

Results

In all, 25 randomized clinical trials with a total of 1,485 patients were included. In surgery, hyperoncotic albumin preserved renal function and reduced intestinal edema compared with control fluids. In trauma and sepsis, cardiac index and oxygenation were higher after administration of hydroxyethyl starch than hyperoncotic albumin. Improved treatment response and renal function, shorter hospital stay and lower costs of care were reported in patients with liver disease receiving hyperoncotic albumin. Edema and morbidity were decreased in high-risk neonates after hyperoncotic albumin administration. Disability was reduced by therapy with hyperoncotic albumin in brain injury. There was no evidence of deleterious effects attributable to hyperoncotic albumin. Survival was unaffected by hyperoncotic albumin (pooled relative risk, 0.95; 95% confidence interval 0.78 to 1.17).

Conclusion

In some clinical indications, randomized trial evidence has suggested certain benefits of hyperoncotic albumin such as reductions in morbidity, renal impairment and edema. However, further clinical trials are needed, particularly in surgery, trauma and sepsis.

[Hemodilution and infusion therapy for hypovolemic shock. Clinical physiological and pharmacological aspects]

Hypovolemic shock is not a form of disease and can be subdivided into four special types with varying therapeutic demands. The decisive approach in the therapy of hypovolemic shock is to initially attain normovolemia by rapid administration of volume replacement agents in the sense of controlled hemodilution. This allows an adequate increase in the cardiac output resulting in delivery of sufficient oxygen to tissues. In the following article the limits of intervention will be described and the advantages and disadvantages of these measures for patients suffering from hypovolemic shock will be critically considered.

Die Behandlung des hämorrhagischen Schocks

The future of shock treatment depends on the importance of scientific results, and the willingness of physicians to optimize, and to reconsider established treatment protocols. There are four major potentially promising approaches to advanced trauma life support. First, control of hemorrhage by administration of local hemostatic agents, and a better, target-controlled management of the coagulation system. Second, improving intravascular volume by recruiting blood from the venous vasculature by preventing mistakes during mechanical ventilation, and by employing alternative spontaneous (i.e. use of the inspiratory threshold valve) or artificial ventilation strategies. In addition, artificial oxygen carriers may improve intravascular volume and oxygen delivery. Third, pharmacologic support of physiologic, endogenous mechanisms involved in the compensation phase of shock, and blockade of pathomechanisms that are known to cause irreversible vasoplegia (arginine vasopressin and K(ATP) channel blockers for hemodynamic stabilization). Fourth, employing potentially protective strategies such as mild or moderate hypothermia. Finally, the ultimate vision of trauma resuscitation is the concept of "suspended animation" as a form of delayed resuscitation after protection of vital organ systems.

Hypertonic-hyperoncotic solutions reduce the release of cardiac troponin I and s-100 after successful cardiopulmonary resuscitation in pigs

In some patients, cardiopulmonary resuscitation (CPR) can revive spontaneous circulation (ROSC). However, neurological outcome often remains poor. Hypertonic-hyperoncotic solutions (HHS) have been shown to improve microvascular conductivity after regional and global ischemia. We investigated the effect of infusion of HHS in a porcine CPR model. Cardiac arrest was induced by ventricular fibrillation. Advanced cardiac life support was begun after 4 min of nonintervention and 1 min of basic life support. Upon ROSC, the animals randomly received 125 mL of either normal saline (placebo, n = 8) or 7.2% NaCl and 10% hydroxyethyl starch 200,000/0.5 (HHS, n = 7). Myocardial and cerebral damage were assessed by serum concentrations of cardiac troponin I and astroglial protein S-100, respectively, up to 240 min after ROSC. In all animals, the levels of cardiac troponin I and S-100 increased after ROSC (P < 0.01). This increase was significantly blunted in animals that received HHS instead of placebo. The use of HHS in the setting of CPR may provide a new option in reducing cell damage in postischemic myocardial and cerebral tissues.

IMPLICATIONS

Infusion of hypertonic-hyperoncotic solutions (HHS) after successful cardiopulmonary resuscitation in pigs significantly reduced the release of cardiac troponin I and cerebral protein S-100, which are sensitive and specific markers of cell damage. Treatment with HHS may provide a new option to improve the outcome of cardiopulmonary resuscitation.

Blood substitutes

Blood substitutes are solutions intended to replace transfusion of banked red blood cells. Several variations of products based on either hemoglobin (animal or human) or perfluorocarbon emulsions are in advanced stages of clinical development. The need for such products is pressing as shortages of banked blood worsen and awareness of the dangers of blood transfusion increases. Animal and human studies with these cell-free oxygen carriers have led to new concepts of how oxygen is delivered to tissue and how the microcirculation is regulated. Although development of products is exciting and timely, understanding how they function to perfuse and oxygenate tissue could be at least as important. Because cell-free oxygen carriers will perfuse every organ of the body, their effects are far-reaching, and the transition from the laboratory to the bedside can be expected to be slow and deliberate. Comparison of oxygen carriers with more traditional starch-based products provides new insight into the interaction of oxygen transport, microvascular perfusion, and blood volume expansion.