Shock fluid resuscitation

Use when an appropriate fluid challenge fails to restore adequate hemodynamics and organ perfusion or in the face of life-threatening shock when fluid challenge is in progress. Should be utilized in patients who have been adequately fluid resuscitated... 

Major treatment goals in hypovolemic shock following fluid resuscitation are as follows arterial systolic blood pressure greater than 90 mm Hg within 1 hour, organ dysfunction reversal, and normalization of laboratory measurements as rapidly as possible (less than 24 hours). 

Successful treatment of hypovolemic shock is measured by the restoration of blood pressure to baseline values and reversal of associated organ dysfunction. The likelihood of a successful fluid resuscitation will be directly related to the expediency of treatment. Therapy goals include ... 

For peritonitis, early and aggressive intravenous fluid resuscitation and electrolyte replacement therapy are essential. A common cause of early death is hypovolemic shock caused by inadequate intravascular volume expansion and tissue perfusion. 

In the early phase of serious intraabdominal infections, attention should be given to preserving major organ system function. With generalized peritonitis, large volumes of intravenous (IV) fluids are required to maintain intravascular volume, to improve cardiovascular function, and to ensure adequate tissue perfusion and oxygenation. Adequate urine output should be maintained to ensure appropriate fluid resuscitation and to preserve renal function. A common cause of early death is hypovolemic shock caused by inadequate intravascular volume expansion and tissue perfusion. 

Septic shock Sepsis with hypotension, despite fluid resuscitation, along with the presence of perfusion abnormalities. Patients who are on inotropic or vasopressor agents may not be hypotensive at the time perfusion abnormalities are measured. Multiple-Organ Dysfunction Syndrome (MODS) Presence of altered organ function requiring intervention to maintain homeostasis. 

Vasopressin levels are increased during hypotension to maintain blood pressure by vasoconstriction. However, there is a vasopressin deficiency in septic shock. Low doses of vasopressin increase MAP, leading to the discontinuation of vasopressors. However, routine use of vasopressin is not recommended because of lack of evidence of efficacy. Vasopressin is a direct vasoconstrictor without inotropic or chronotropic effects and may result in decreased cardiac output and hepatosplanchnic flow. Vasopressin use may be considered in patients with refractory shock despite adequate fluid resuscitation and high-dose vasopressors.24,27-28... 

Adequate fluid resuscitation to maintain circulating blood volume is essential in managing all forms of shock. Different therapeutic options are discussed in the next section. 

Initial fluid resuscitation consists of isotonic crystalloid (0.9% sodium chloride or lariated Ringer s solution), colloid (5% Plasmanate or albumin, 6% hetastarch), or whole blood. Choice of solution is based on 02-carrying capacity (e.g., hemoglobin, hematocrit), cause of hypovolemic shock, accompanying disease states, degree of fluid loss, and required speed of fluid delivery. 

Vasopressin causes vasoconstrictive effects that, unlike adrenergic receptor agonists, are preserved during hypoxia and severe acidosis. It also causes vasodilation in the pulmonary, coronary, and selected renal vascular beds that may reduce pulmonary artery pressure and preserve cardiac and renal function. However, based on available evidence, vasopressin is not recommended as a replacement for norepinephrine or dopamine in patients with septic shock but may be considered in patients who are refractory to catecholamine vasopressors despite adequate fluid resuscitation. If used, the dose should not exceed 0.01 to 0.04 units/min. 

Systemic infections are those that have microorganisms (bacteria, viruses, yeasts, parasites) spread, usually via the bloodstream, beyond the portal of entry or original site of localized infection to multiple compartments of the body. When infections, either localized or systemic, are accompanied by signs and symptoms of a systemic inflammatory response (fever, rapid pulse, increase in white blood cells) the syndrome is called sepsis. Severe sepsis is defined by the additional occurrence of organ failure (either kidney, liver, brain, lungs), and is a potentially fatal condition (mortality around 50%). If there is hypotension not responding on fluid resuscitation it is called septic shock and the mortally is even higher (60-70%). 

Extensive burn injuries produce a systemic response that pulls fluid from the vascular system into the interstitial space. This is exacerbated in burns greater than 20% TBSA by a significant capillary leak into the microvasculature and generalized edema. Without proper treatment, intravascular fluid loss and hypovolemic burn shock result. This is why immediate initiation of fluid resuscitation is important. A successful fluid resuscitation will maintain intravascular volume and organ perfusion until capillary membrane integrity is restored (approximately 24 to 48 hours postinjury). 

After adequate fluid resuscitation has been established, inotropic support is usually required. Noradrenaline is the inotrope of choice for septic shock its potent a-adrenergic effect increases the mean arterial pressure and its modest Pj effect may raise cardiac output, or at least maintain it as the peripheral vascular resistance increases. Dobutamine may be added further to augment cardiac output. 

Kerger, II. Tsai, A.G. Saltzman, D.J. Winslow, R.M. Intaglietta, M. Fluid resuscitation with O2 Vs. non-02 carriers after 2H of hemorrhagic shock in conscious hamsters. Am. J. Physiol. 1997, 272, H525-H537(Heart Circ Physiol 41). 

Journal of Trauma 46 216-223 Carcillo J A, Davis A L, Zaritsky A 1991 Role of early fluid resuscitation in pediatric septic shock. Journal of the American Medical Association 266 1242-1245 Carlson G P 1999 Quantative estimation of fluid and electrolyte deficits. In Proceedings of the Bluegrass Equine Medical and Critical Care Symposium, Lexington, KY 1999 pp. 

Early goal-directed therapy with aggressive fluid resuscitation in the emergency department within the first 6 hours of presentation improves survival in sepsis and septic shock. 

There are three clinical trials using phenylephrine in septic shock evaluating 38 patients. Phenylephrine (0.5 to 9 mcg/kg per minute), when used alone or in combination with dobutamine or low doses of dopamine, improves blood pressure and myocardial performance in fluid-resuscitated septic patients. Incremental doses of phenylephrine over 3 hours result in linear dose-related increases in MAP, SVR, heart rate, and stroke index when administered as a single agent in stable, nonhypotensive but hyperdynamic, volume-resuscitated... 

Isotonic crystalloids, such as 0.9% sodium chloride (normal saline) or lactated Ringer s solution, are used commonly for fluid resuscitation. A patient in septic shock typically requires up to 10 L of crystalloid solution during the first 24-hour period. These solutions distribute into the extracellular compartment. Approximately 25% of the infused volume of crystalloid remains in the intravascular space, whereas the balance distributes to extravascular spaces. Although this could impair diffusion of oxygen to tissues, clinical impact is unproven. 

Phenylephrine, a selective a i-agonist, has a rapid onset, short duration, and primary vascular effects, making it an attractive agent in the management of hypotension associated with septic shock. The limited available information suggests that it can increase blood pressure in fluid-resuscitated patients, and it does not appear to impair cardiac or renal function. Phenylephrine appears useful when tachycardia limits the use of other vasopressors. 

McSwain NE, Frame S, Paturas, JL, eds. Shock and Fluid Resuscitation in Basic and Advanced Prehospital Trauma Life Support. 4th Ed. St. Louis, MO Mosby, 1999. 

Antimony. Large-volume intravenous fluid resuscitation may be necessary for shock caused by gastroenteritis (see p 16). 

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