Crystalloid versus Colloids: Optimizing Fluid Resuscitation Following Trauma
Blunt force trauma to the chest cavity can cause tremendous structural damage, resulting in compromised functional integrity to essential organs, such as the heart and the lungs. Because these primary organs facilitate perfusion to the rest of the body, damage can result in massive hypoperfusion leading to shock. Many researchers concur on the subject of fluid resuscitation to abate affects of cardiogenic shock and even death; however, the debate arises when considering types of fluid resuscitative therapy. Perpetual debates and literature has advocated for resuscitation with either crystalloid or colloid; supporting studies proclaim that one is superior to the other. To provide adequate treatment for patients experiencing cardiogenic shock, the practitioner must understand the pathophysiology of cardiac trauma and the anesthetic goals, and the role albumin plays in metabolic activity; furthermore, the practitioner should be aware of current literature contrasting crystalloid and colloid therapy in cardiogenic shock treatment.
Pathophysiology of Cardiac Trauma and Anesthetic Goals
Penetrating cardiac injuries often lead to immediate cardiovascular collapse, which patients rarely survive. Injuries associated with penetrating cardiac trauma include pericardial tamponade, cardiac perforation, rupture of a chamber, and fistula formation. Blunt cardiac trauma injuries include cardiac contusion; which are most common, pericardial ruptures, rupture of a chamber, valvular tears, coronary artery injuries, and ventricular aneurysms. The primary complication of pericardial tamponade is a decrease in cardiac output secondary to pericardial pressure causing severe diastolic dysfunction.
Cardiac tamponade, which occurs when the pericardial sac surrounding the heart begins to fill with blood, can severe reduce forward flow. It presents as Beck’s triad: hypotension, distended neck veins, muffled heart sounds and pulsus paradoxus (Yao, 2012). The decrement of cardiac output by way of either these pathophysiologies can severely decrease perfusion to the renal, hepatic and neurological systems. Due to the decrease in oxygen deliver, metabolic acidosis can ultimately result.
The anesthetic goal for treating acute cardiac trauma and cardiogenic shock is to maintain intrinsic sympathetic tone and preload (Yao, 2012). Therefore, use of vasopressors is essential. When considering maintenance of preload, researchers who advocate for resuscitation with colloids argue that albumin plays a major role in metabolic activity; therefore, it not only replaces volume, but it also induces essential metabolic activity that aids in healing and drug delivery.
The role of Albumin in Metabolic Activity
Serum albumin is a single-chain protein synthesized in and secreted from liver cells. Many researchers have studied the structure of serum albumin, its properties and functions to understand the protein’s interactions with a number of ligands (Alekseev & Rebane, 2012). It has been discovered that albumin not only acts as a carrier protein for drugs, but also participates in catabolic activity such as hydrolysis. The albumin molecule consist of three domains: I, II and III; each of these domains have a subdomain A and subdomain B. Researchers has found these subdomains of the albumin molecule are essential for binding and transportation of antibiotics as well as other pharmaceuticals. The domain II and III of albumin contain two primary drug binding sites, known as Sudlow’s site I and site II (Alekseev & Rebane, 2012).
Albumin has been reported to exert irreversible effects on some beta lactam antibiotics. It was found that albumin of different purity obtained from a variety of sources, showed significant beta-lactamase activity.
Purified albumin was shown to have a hydrolase activity, catalyzing the decomposition of the chromogenic cephalosporin. Furthermore, It was found that only cefuroxime, ceftazidime and cefoperazone interacted slightly with site I on serum albumin, while site II possessed the capacity to bind cephradine, cephalexin, ceftazidime, ceftriaxone, cefoperazone, cefaclor and cefsulodin (Alekseev & Rebane, 2012). Therefore, albumin may facilitate healing by ensure the effective transport of antibiotics, which can decrease risk of infection and sepsis, which can lead to the triad of death. Along with the deliver of drugs, it is essential to maintain normal cellular activity, which is done through by series of serum enzymes such as esterase.
Albumin plays a key role in hydrolytic activity. Stability of albumin was observed under conditions unfavorable for other blood serum esterases, in particular, in the absence of necessary co-factors, in the presence of specific inhibitors, or after preliminary heating. It was found that albumin was able to maintain its structure to a greater degree than other serum esterases. However, albumin hydrolysis activity turnover time is considerable slower than other esterase; thus, catalytic activity of serum albumin is classified as esterase-like or pseudo-esterase activity (Alekseev & Rebane, 2012). Nonetheless, because of its sustainability and contribution of to catabolic activity, albumin replacement is essential.
Contrast effects of crystalloid and colloid resuscitation
When trauma occurs, replacing intravascular volume is pertinent to abate cardiac failure, which can lead to cardiogenic shock. The rationale lies in the ideal that replacing intravascular volume restores normal circulatory and metabolic activity; furthermore, it prevents continuous capillary leakage (Lira & Pinsky, 2014). Plasma, water, and solutes freely associate and move from the intravascular into the interstitial space at least once in a day. This movement is attributed by greater hydrostatic pressure in the vascular space, as compared in the interstitial space and the level of permeability of the vascular endothelium. Fluid return to the vascular space is minimal due to reabsorption by the lymphatic system (Lira & Pinsky, 2014). This binary system for fluid can prevent obstruction of the lymphatic system and vascular overload.
In the event of trauma, a marked reduction in the vascular endothelial junction occurs.
When tissue injury occurs, as often is the case in acute cardiac trauma, vascular endothelial tight junction disruption will also occur in areas typically relatively resistant to fluid translocation (Lira & Pinsky, 2014). This translocation of fluid can result in edema. Since different vascular regions of the body allow proteins to pass through the capillary membrane at different rates, as exemplified by the loose barrier in the liver and tight barrier in the brain, interstitial edema formation is not usually uniform throughout the body. Thus, the metabolic effect of differentially altered permeability and plasma leak may play a role in the regional expression of a generalized inflammatory response. Since most, if not all, fluid return from the extravascular space to the vasculature happens via lymphatic drainage, if transcapillary leakage is increased, the lymphatic system may become overwhelmed, further contributing to the development of edema and a relative intravascular volume deficit despite no actual loss of fluid outside the body (Lira & Pinsky, 2014).
Continuous lost of fluid to the interstitial space can cause compression of organs, such as in cardiac tamponade and render them functional crippled. The intuitive thought concerning albumin, considering its hydrostatic effects, would be that it would draw the leakage into the vascular space; therefore, adding to vascular volume and decreasing the futile state of edema.
Regrettably, according to the theoretical model by Lira & Pinsky (2014) this intuitive thought cannot be actualized. Lira & Pinsky (2014) found that volume requirements during resuscitation in septic shock with either albumin or crystalloids are similar when both fluids are given in a blinded fashion. Indeed, even if the goal were to sustain a normal intravascular oncotic pressure, it has been repeatedly observed that the most balanced approach does not occur with infusion of colloids to crystalloids at a ratio of 1:3 as initially postulated, but rather 1:1.3. Furthermore, due to the increased capillary permeability in critical illness, which results in accumulation of both fluid, and macromolecules in the extracellular space, colloids may theoretically worsen edema by increasing interstitial oncotic pressure, resulting in further impediment of tissue perfusion and lymphatic return (Lira & Pinsky, 2014). Thus, at the risk that albumin can contribute to edema because of broken tight junctions, it may behoove the practitioner to initial replace with crystalloids. However, it cannot be disputed that albumin possess essential qualities, so incorporation of both crystalloids and colloids may prove to be beneficial.
Blunt force trauma to the chest cavity can have devastating effects. Penetrating wounds to vital organs, such as the heart and lungs can be fatal; therefore, controlling variation of injuries, such as cardiac tamponade, hemorrhage and cardiogenic shock can prove to be a challenge to the practitioner. Understanding the pathophysiology of such conditions, such as breaking of the endothelial tissue and capillary leakage, is imperative to evoke an effective plan of treatment. It stands without debate that fluid resuscitation in all trauma cases is essential. However, when considering the pathophysiology of trauma and damage to internal structures, advocating for either crystalloids or colloids, may not be the solution. Albumin has many beneficial qualities, such as metabolic activity facilitation and ligand carrying capacity; however, in early stages of trauma, it may contribute to the detrimental cycle of capillary leakage and edema. Thus it can be concluded that uses of a mix therapy, crystalloids and colloids, can optimize circulation.
Alekseev, R., & Rebane, A. (2012). Protein biochemistry, synthesis, structure and cellular functions: Serum albumin: Structure, Function and Health Impact. New York, NY: Nova. Retrieved from http://www.ebrary.com
Khalid, R. (2012, July 16). Cardiogenic shock. Healthline. Retrieved from http://www.healthline.com/health/cardiogenic-shock#Overview1
Lira, A., & Pinsky, M. (2014, Dec 4). Choices in fluid type and volume during resuscitation: impact on patient outcomes. Annals of Intensive Care , 4(38), 1-13. http://dx.doi.org/10.1186/s13613-014-0038-4
Yao, F. F. (2012). Yao & Artusio’s Anesthesiology (7th ed.). Retrieved from http://www.r2library.com.une.idm.oclc.org/resource/title/1451102658