Fluid replacement

Oral rehydration therapy (ORT) is a simple treatment for dehydration associated with diarrhea, particularly gastroenteritis/gastroenteropathy, such as that caused by cholera or rotavirus. ORT consists of a solution of salts and sugars which is taken by mouth. For most mild to moderate dehydration in children, the preferable treatment in an emergency department is ORT over intravenous replacement of fluid. It is used around the world, but is most important in the developing world, where it saves millions of children a year from death due to diarrhea—the second leading cause of death in children under five. ==Intravenous==

Similar precaution should be taken in administration of resuscitation fluid as to drug prescription. Fluid replacement should be considered as part of the complex physiological in the human body. Therefore, fluid requirements should be adjusted from time to time in those who are severely ill. In severe dehydration, intravenous fluid replacement is preferred, and may be lifesaving. It is especially useful where there is depletion of fluid both in the intracellular space and the vascular spaces. Fluid replacement is also indicated in fluid depletion due to hemorrhage, extensive burns and excessive sweating (as from a prolonged fever), and prolonged diarrhea (cholera). During surgical procedures, fluid requirement increases by increased evaporation, fluid shifts, or excessive urine production, among other possible causes. Even a small surgery may cause a loss of approximately 4 ml/kg/hour, and a large surgery approximately 8 ml/kg/hour, in addition to the basal fluid requirement. The table to the right shows daily requirements for some major fluid components. If these cannot be given enterally, they may need to be given entirely intravenously. If continued long-term (more than approx. 2 days), a more complete regimen of total parenteral nutrition may be required. Types Resuscitation fluid can be broadly classified into: albumin solution, semisynthetic colloids, and crystalloids. Maintenance Maintenance fluids are used in those who are currently normally hydrated but unable to drink enough to maintain this hydration. In children isotonic fluids are generally recommended for maintaining hydration. The amount of maintenance IV fluid required in 24 hours is based on the weight of the patient using the Holliday-Segar formula. For weights ranging from 0 to 10 kg, the caloric expenditure is 100 cal/kg/day; from 10 to 20 kg the caloric expenditure is 1000 cal plus 50 cal/kg for each kilogram of body weight more than 10; over 20 kg the caloric expenditure is 1500 cal plus 20 cal/kg for each kilogram more than 20. More complex calculations (e.g., those using body surface area) are rarely required. Procedure It is important to achieve a fluid status that is good enough to avoid low urine production. Low urine output has various limits, and varies for children, infants, and adults (see low urine production). The Parkland formula is not perfect and fluid therapy will need to be titrated to hemodynamic values and urine output. The speed of fluid replacement may differ between procedures. For example, the planning of fluid replacement for burn patients is based on the Parkland formula (4mL Lactated Ringers X weight in kg X % total body surface area burned = Amount of fluid ( in ml) to give over 24 hours). The Parkland formula gives the minimum amount to be given in 24 hours. Half of the volume is given over the first eight hours after the time of the burn (not from time of admission to hospital) and the other half over the next 16 hours. In dehydration, 2/3 of the deficit may be given in 4 hours, and the rest during approximately 20 hours. ==Clinical uses==

Septic shock Fluid replacement in patients with septic shock can be divided into four stages as shown below: • Resuscitation phase - The goal of this phase is to correct the hypotension. Intravenous crystalloid is the first choice of therapy. Surviving Sepsis Campaign recommends 30 ml/kg fluid resuscitation in this phase. Earlier fluid resuscitation is associated with improved survival. Mean arterial pressure should be targeted at more than 65 mmHg. Higher mean arterial pressures can be used in patients with chronic hypertension in order to reduce the usage of renal replacement therapy. However, if fluid replacement is inadequate in raising blood pressure, then vasopressor have to be used. However, there is no definite timing of starting vasopressors. Initiation of vasopressors within the first hour of sepsis can lead to poor organ perfusion and poor organ function. Late initiation of vasopressor can lead to organ damage and increase the risk of death. Frequent monitoring of fluid status of the patient is required to prevent fluid overload. • Optimisation phase - In this phase, the goal is to increase the oxygen delivery to tissues in order to meet the oxygen demands of the tissues. Oxygen delivery can be improved by increasing stroke volume of the heart (through fluid challenge), haemoglobin concentration (through blood transfusion), and arterial oxygen saturation (through oxygen therapy). Fluid challenge is the procedure of giving large amounts of fluid in a short period of time. However, 50% of patients do not respond to fluid challenge. Additional fluid challenges only causes fluid overload. However, there is no gold standard on determining the fluid responsiveness. Among other ways of determining the fluid responsiveness and the end point of fluid resuscitation are: Central venous oxygen saturation (ScvO2), passive leg raising test, ultrasound measurements of pulse pressure variation, stroke volume variation, and respiratory variations at superior vena cava, inferior vena cava and internal jugular vein. In acute respiratory distress syndrome (ARDS), conservative fluid management is associated with better oxygenation and lung function with less prevalence of dialysis in the first 60 days of hospitalization when compared with liberal fluid management. The goal of fluid therapy is to maintain fluid and electrolyte levels and restore levels that may be depleted. Intravenous fluid therapy is used when a person cannot control their own fluid intake and it can also reduce nausea and vomiting. Goal-directed fluid therapy is a perioperative strategy in which the person is administered fluids continuously and the amount of fluids given are based on the person's physiological and haemodynamic (blood flow) measurements. A second approach to fluid management during surgical procedures is called perioperative restrictive fluid therapy, also known as near-zero or zero-balance perioperative fluid approach; this approach recommends lower amounts of fluids during surgery, replacing fluids when the person is low (basal fluid requirements) or loses fluid due to a surgical procedure or bleed. The effectiveness of goal-directed fluid therapy compared to restrictive fluid therapy is not clear as evidence comparing both approaches have very low certainty. ==Fluid overload==

Fluid overload is defined as an increase in body weight of over 10%. ==Other treatments==

Proctoclysis, an enema, is the administration of fluid into the rectum as a hydration therapy. It is sometimes used for very ill persons with cancer. The Murphy drip is a device by means of which this treatment may be performed. ==See also==