الفهرس 
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Abstract
The patient suffered from a major burn has undergone one of the most severe forms of trauma. This injury results in loss of the essential function of the skin, which is the largest organ in the body that protects it from heat loss, evaporative losses of fluids and microbial invasion.
The treatment of patients with extensive burns remains a major challenge due to the lack of available autologous skin. Even with advances in burn care over recent decades, rates of mortality remain high among severely burned patients. Recent U.S. data indicate a 69% mortality rate among patients with burns over 70% of the total body surface area (TBSA).
Burn shock is a complex process of circulatory and microcirculatory dysfunction, not easily nor fully repaired by fluid resuscitation. Severe burn injury results in significant hypovolemic shock and substantial tissue trauma, both of which cause the formation and release of many local and systemic mediators.these mediators released from damaged tissues and cause increased capillary permeability.
The increased capillary permeability is a part of the edema process, especially in full thickness burns, where most of the capillary bed is occluded soon after injury. The protein rapidly leaves the plasma space through the “leaky” capillaries into the burn. Therefore, the effect of plasma colloid osmotic pressure is markedly diminished.
Early fluid resuscitation of burn shock proved to be effective in restoring normal tissue oxygenation to minimize complications and improve outcome. When resuscitation is delayed, recovery can be complicated by sepsis and multiple organ failure secondary to prolonged tissue hypoxia and reperfusion injury.
Fluid resuscitation is aimed at supporting the patient throughout the initial 24 to 48-hours period of hypovolemia. The primary goal of therapy is to replace the fluid sequestered as a result of thermal injury. The critical concept in burn shock is that massive fluids shifts can occur even though total body water remains unchanged. The resuscitation fluids should be minimized to decrease iatrogenic complication such as abdominal compartment syndrome. trials of alternate fluid types like hypertonic solutions, colloids and dextran, as original resuscitation efforts frequently lead to over-resuscitation.
Several resuscitation formulae for calculation of the fluid requirement are used worldwide. The best known formulae are: Evans, Brooke, modified Brooke, Monafo and Parkland.
The first documented interest in studying burn shock resuscitation was tied to burn disasters. Underhill published his experience with the Rialto Theater fire in 1921. He documented the understanding that burn shock was related to fluid loss. The Coconut Grove disaster in 1942 was an impetus for many developments in burn care. The first burn resuscitation formula on body surface area burn and bodyweight was described by Evans in 1952. The “Evans Formula” was the standard for years. Clearly, a major focus of research during the 1960s and 1970s was the investigation of fluid shifts during the first 24 hours after burn injury. There has not been such an effort since that time. One of the key figures in burn resuscitation was Charles Baxter, who was instrumental in developing the Parkland Formula, which today is the most frequently used resuscitation formula. He and his colleagues understood that fluid requirements should be dictated by the urine output of the burn patients. He also realized that this was an approximation and the best indicator of fluid requirements should be based on urine output. The “Parkland Formula” has remained the most commonly used formula today.
Monitoring of burn shock resuscitation had traditionally relied on clinical assessment of cardiovascularand renal systems and biochemical parameters as indicators of vital organ perfusion. Heart rate, blood pressure, and electrocardiographic recordings are the primary modalities for monitoring the cardiovascular status in any patient. In major burns, the traditional clinical parameters (urine output and mean arterial blood pressure) provide insufficient information to serve as a guide for resuscitation. Other semi invasive or invasive methods have some potential hazards and need expensive equipment. The Pulmonary Artery Catheter (PAC), Central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP) and blood lactate level has been suggested as resuscitative parameters.
Ideal endpoints in major burn fluid resuscitation are still a matter of controversial discussion in the literature. Several formulas have been developed to estimate the required fluid amount. Fluid administration should be adjusted to the individual needs of the patient. Hence, it is important to identify treatment-related factors influencing survival of patients with severe burns.
In our study we review the pathophysiology of burn shock and edema, the fluid resuscitation of burn shock and the endpoints of monitoring of adequacy of fluid resuscitation. Despite the great effort done in developing of several resuscitation formulas and new techniques in patient monitoring no resuscitation formula prove to be superior in patient resuscitation. The “Parkland Formula” has remained the most commonly used formula today.
In patient monitoring the traditional end points of monitoring like urine output, heart rate and mean arterial blood pressure lack the accuracy needed in burn shock resuscitation and frequently lead to over resuscitation. The advanced methods like pulmonary artery catheter and transpulmonary thermodilution technique are invasive, carry high risk of morbidity and mortality, high cost and unavailable in many centers.so the combination between laboratory investigations like blood lactate level and base deficit and clinical parameters especially peripheral skin temperature and urine output seem to be a good option in monitoring of burn shock resuscitation.