Fluid therapy requirements

During the administration of fluids, the newborn infant requires that one periodically assay for the various conq>onents discussed above, so as to see whether the fluids being administered are serving their purpose or need to be changed. The newborn infant does not have the reserve capacity that the adult has in being able to buffer and adjust for various problems which may arise during fluid therapy. For this reason, the newborn infant during acute treatment may require repetitive analyses, at relatively short intervals. Even when the condition is stabilized it is customary for the pediatrician to require analyses for electrolytes at periodic intervals for the security of the patient. 

What initial pharmacologic/fluid therapy is required at this time ... 

The clinical scenario and the severity of the volume abnormality dictate monitoring parameters during fluid replacement therapy. These may include a subjective sense of thirst, mental status, skin turgor, orthostatic vital signs, pulse rate, weight changes, blood chemistries, fluid input and output, central venous pressure, pulmonary capillary wedge pressure, and cardiac output. Fluid replacement requires particular caution in patient populations at risk of fluid overload, such as those with renal failure, cardiac failure, hepatic failure, or the elderly. Other complications of IV fluid therapy include infiltration, infection, phlebitis, thrombophlebitis, and extravasation. 

In patients with peritonitis, hypovolemia is often accompanied by acidosis, so large volumes of a solution such as lac-tated Ringers may be required initially to restore intravascular volume. Maintenance fluids should be instituted (after intravascular volume is restored) with 0.9% sodium chloride and potassium chloride (20 mEq/L) or 5% dextrose and 0.45% sodium chloride with potassium chloride (20 mEq/L). The administration rate should be based on estimated daily fluid loss through urine and nasogastric suction, including 0.5 to 1.0 L for insensible fluid loss. Potassium would not be included routinely if the patient is hyperkalemic or has renal insufficiency. Aggressive fluid therapy often must be continued in the postoperative period because fluid will continue to sequester in the peritoneal cavity, bowel wall, and lumen. 

Concentrated sodium chioride- As an additive in parenteral fluid therapy for use in patients who have special problems of sodium electrolyte intake or excretion. It is intended to meet the specific requirements of the patient with unusual fluid and electrolyte needs. After available clinical and laboratory information is considered and correlated, determine the appropriate number of milliequivalents of concentrated sodium chloride injection, USP and dilute for use. 

The dosage as an additive in parenteral fluid therapy is predicated on specific requirements of the patient. The appropriate volume is then withdrawn for proper dilution. Having determined the mEq of sodium chloride to be added, divide by 4 to calculate the number of mL to be used. Withdraw this volume and transfer into appropriate IV solutions, such as 5% dextrose injection. The properly diluted solution may be given IV. 

The fundamental treatment for DKA includes aggressive intravenous hydration and insulin therapy and maintenance of potassium and other electrolyte levels. Fluid and insulin therapy is based on the patient s individual needs and requires frequent reevaluation and modification. Close attention has to be given to hydration and renal status, the sodium and potassium levels, and the rate of correction of plasma glucose and plasma osmolality. Fluid therapy generally begins with normal saline. Regular human insulin should be used for intravenous therapy with a usual starting dose of about 0.1 IU/kg/h. 

Sodium When patients present with hypernatremia and elevated serum osmolality, they are suffering from severe fluid deficits. Depending on the patient s hemodynamic stability, fluid therapy should generally be instituted as a moderate-to-slow intravenous infusion of 0.9% normal saline over a period of 48-72 h to avoid cerebral edema. Patients with evidence of circulatory compromise will require more aggressive fluid resuscitation. Estimated plasma osmolality and corrected serum sodium concentrations are calculated using the following formulas ... 

Conditions that result in the loss of large volumes of body fluids, such as high-volume diarrhea and gastric reflux, obviously require aggressive fluid therapy. However, many other horses may require fluid therapy because of prolonged mild-to-moderate fluid losses or prolonged reduced fluid intake. In neonatal foals, reduced fluid intake can rapidly result in hypovolemia and severe dehydration. This section addresses the identification of these horses and foals. 

The use of colloids has recently been advocated for the resuscitation of hypovolemic horses and for the treatment of severe hypoproteinemia (McFarlane 1999). Colloids have two advantages over crystalloids that makes them attractive for fluid therapy. Firstly, because of their persistence in the circulation, a three to six times lower volume of a colloid solution is required to produce the same resuscitative effect as a crystalloid solution (Rackow et al 1987). This is particularly useful in acute resuscitation of severely dehydrated horses or in the field where large amounts of crystalloids may be difficult to transport. Secondly, the administration of colloids can increase colloidal oncotic pressure, in contrast to the administration of large volumes of crystalloids, which decreases the colloidal oncotic pressure (Jones et al 1997,2001). 

The goal of the maintenance phase of fluid therapy is to supply the basal fluid requirement of the horse ("maintenance" rate) and replace ongoing fluid losses. The mean daily water intake (including the water content of feed) of normal... 

Clinically, the animals do not show signs until 24-48 or more hours after ingestion of the bait. The affected animals are depressed, have reduced urine production, and the urine is of low specific gravity. Severely poisoned animals have hematemesis, azotemia, and cardiac arrhythmias. Animals with renal impairment are more susceptible to cholecalciferol poisoning than those with normal renal function. Cholecalciferol poisoning requires protracted treatment, which may require as long as 3 weeks in severe intoxications. Appropriate treatment consists of fluid therapy to assist the kidneys in removing the excess calcium, corticosteroids to minimize inflammation, and calcitonin to enhance calcium resorption into the bone. Pamidronate disodium is the new antidote for this poison. 

HD is the most common method used to treat advanced and permanent kidney failure. Clinically, it is considered the default therapy that is utilized in the increasing numbers of patients unsuitable for other modalities of PD and kidney transplantation. Operationally, it involves connecting the patient to a hemodialyzer into which their blood flows. After filtration to remove the wastes and extra fluids, the cleansed blood is returned to the patient. It is stfll a complicated and inconvenient therapy requiring a coordinated effort from a healthcare team that includes the patient, nephrologist, dialysis nurse, dialysis technician, dietitian, and others. 

Aggressive fluid repletion and management are required for successful treatment of intraabdominal infections. Fluid therapy is instituted for the purposes of achieving or maintaining proper intravascular volume to ensure adequate cardiac output, tissue perfusion, and correction of acidosis. Loss of fluid through vomiting, diarrhea, or a nasogastric suction contributes to dehydration. Intravascular volume can be assessed by blood pressure and heart rate but more accurately... 

Septic patients have enormous fluid requirements as a result of peripheral vasodilation and capillary leakage. Rapid fluid resuscitation is the best initial therapeutic intervention for the treatment of hypotension in sepsis. The goal of fluid therapy is to maximize cardiac output by increasing the left ventricular preload, which ultimately will restore tissue perfusion. Fluid administration should be titrated to clinical end points such as heart rate, urine output, blood pressure, and mental status. An increased serum lactate level, a byproduct of cellular anaerobic metabolism, should normalize as the tissue perfusion improves. 

What other information do you require in order to prescribe the appropriate fluid therapy ... 

Crush injuries from collapsing buildings are common in terrorist bombings. Clinically, they do not differ from crush due to other causes, except in the nature of the associated injuries. Conventional treatment protocols should be followed. Crush injury to tissues, usually of the limbs, may require fasciotomy and debridement. Crush syndrome is managed with copious intravenous fluids and renal replacement therapy if required. Huid balance should be carefully monitored and fluid therapy may need reduction in the presence of active uncontrolled haemorrhage. Electrolyte imbalance must be monitored and corrected. 

Monitoring the patient in shock requires vigilance on the part of the nurse The patient s heart rate, blood pressure, and ECG are monitored continuously. The urinary output is measured often (usually hourly), and an accurate intake and output is taken. Monitoring of central venous pressure via a central venous catheter will provide an estimation of the patient s fluid status. Sometimes additional hemodynamic monitoring is necessary with a pulmonary artery catheter. The use of a pulmonary artery catheter allows the nurse to monitor a number of parameters, such as cardiac output and peripheral vascular resistance The nurse adjusts therapy according to the primary health care provider s instructions. 

Dryness of the mouth and throat caused by die cholinergic blocking action of this drug also may occur. The nurse provides an adequate amount of fluid and instructs die patient to take frequent sips of water to relieve diis problem. In addition, postural hypotension may occur during die first few weeks of disopyramide therapy. The patient is advised to make position changes slowly. In some instances, the patient may require assistance in getting out of the bed or chair. 

Whether a fluid or electrolyte imbalance occurs depends on the amount of fluid and electrolytes lost and the ability of the individual to replace them. For example, if a patient receiving a diuretic eats poorly and does not drink extra fluids, an electrolyte and water imbalance is likely to occur, especially during initial therapy with the drug. However, even when a patient drinks adequate amounts of fluid and eats a balanced diet, an electrolyte imbalance may still occur and require electrolyte replacement (see Chapter 58 and Display 58-2 for additional discussion of fluid and electrolyte imbalances). 

When normal enteral feeding in not possible or is inadequate to meet an individual s nutritional needs, intravenous (IV) nutritional therapy or total parenteral nutrition (TPN) is required. Products used to meet the IV nutritional requirements of the patient include protein substrates (amino acids), energy substrates (dextrose and fat emulsions), fluids, electrolytes, and trace minerals (see the Summary Drug Table Electrolytes). 

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