Fluid therapy phases

The fluid therapy plan should be divided into three stages initial resuscitation, rehydration and maintenance. The focus of resuscitation is the rapid reversal of hypovolemia. Rehydration aims to replace fluid losses. The maintenance phase aims to prevent the occurrence of further fluid deficits. In severely hypovolemic horses, a transition phase, in which fluid rates are higher than those calculated for the rehydration phase, may be necessary after initial resuscitation. The need for this should be assessed based on the clinical and laboratory responses to the initial resuscitation. Although plasma electrolyte imbalances may... 

The rehydration phase aims to replace extravascular fluid losses. Crystalloid fluids are a logical choice for rehydration as they readily diffuse into the interstitial fluid from the vasculature (Spalding Goodwin 1999, Vaupshas Levy 1990). Rehydration should take place over the first 12-24 h of therapy. The amount given should be based on the clinical estimate of the degree of dehydration and the response to fluid therapy. 

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... 

The volume to be infused and rate of delivery are only part of the therapeutic plan for fluid therapy, albeit the most important in acute resuscitation. The electrolyte and acid-base status of the horse should also be considered and fluids chosen to help to correct physiological imbalances. Unfortunately, it is not possible to predict electrolyte and acid-base disturbances accurately based on clinical signs. Seemingly similar clinical presentations may have a quite different pathophysiology (Brownlow Hutchins 1982, Svendsen et al 1979). The recent availability of relatively inexpensive, portable blood gas and electrolyte measuring equipment (Grosenbaugh et al 1998) has made determining the acid-base status possible in ambulatory equine practice and allows the field veterinarian to monitor and treat these disturbances. As stated earlier, in the absence of specific laboratory information, fluid therapy should probably be limited to isotonic polyionic crystalloid fluids, possibly with the addition of 10-20 mEq/1 potassium chloride in the maintenance phase. 

Mezlocillin, piperacillin, and ticarcillin are parenteral antibiotics formulated as sodium salts, so prescribers must consider the sodium content of these antibiotics when administering them to patients with congestive heart failure. During their distribution phase, antipseudomonal penicillins achieve orfly low concentrations in the cerebrospinal fluid. Consequently, antipseudomonal penicillins are not among the drugs of first choice for meningitis therapy. 

The pharmacokinetic properties of aztreonam are similar to those of the parenteral cephalosporins (Table 45.2). Aztreonam is not bioavailable after oral administration. During its distribution phase, the drug can achieve therapeutic concentrations in cerebrospinal fluid in the presence of inflamed meninges. Consequently, aztreonam is an alternative antibiotic to the cephalosporins for the therapy of meningitis caused by gram-negative bacilli. 

Fluid balance The total amount of fluid the patient takes in (including any from drug therapy) and excretes (urine) must be monitored. In the acute phase the aim is to remove more than is taken in and to limit the patient s fluid intake. 

Normally, the daily fluid Intake is 1,700-2,200 ml this includes water in a bound form (e.g. in fruit, yoghurt, tomatoes). If this amount is clearly reduced or exceeded, the cirrhotic patient may suffer considerable pathophysiological disturbances. From the clinical point of view, however, it is recommended to limit the fluid intake to 1,400-1,600 ml/day during this phase of therapy (in cases of hyponatraemia even to 800 ml). An increase in... 

Imatinib is relatively well tolerated, but it has some significant adverse effects. Some of the most common side effects include nausea, vomiting, diarrhea, edema, muscle cramps, and rash. The edema is usually characterized by periorbital swelling or lower limb edema but may manifest as pleural effusions, ascites, and pulmonary edema. The fluid retention is often managed with dose reduction, diuretics and other supportive care measures. Imatinib also may be associated with cytopenias (primarily neutropenia and thrombocytopenia). These effects are thought to be dose related and are more common in patients with accelerated phase or blast crisis compared with chronic phase CML. Dose reduction or interruption in imatinib therapy may be considered to manage the cytopenias. 

Initial treatment of the acute phase of lead intoxication involves supportive measures. Prevention of further exposure is important. Seizures are treated with diazepam or phenytoin (see Chapter 19), fluid and electrolyte balances must be maintained, and cerebral edema is treated with mannitol and dexamethasone or controlled hyperventilation. The concentration of lead in blood should be determined or at least a blood sample obtained for analysis prior to initiation of chelation therapy. Chelation therapy is indicated in symptomatic patients or in patients with a blood lead concentration in excess of 50-60 pg/dL (about 2.5 pM). Four chelators are employed edetate calcium disodium (CaNa EDTA), dimercaprol, D-penicillamine, and succimer (2,3-dimercaptosuccinic acid [DMSA], chemet). CaNa EDTA and dimercaprol usually are used in combination for lead encephalopathy. 

Because clot-bound thrombin is less effectively inhibited by UFH (attachment of fibrin to the fibrin-binding domain makes the heparinbinding domain inaccessible), it was proposed that the direct antithrombins had an advantage over UFH in STEMI patients treated with a fibrinolytic because of their greater ability to block both fluid-phase and clotbound thrombin. This thrombin hypothesis was the basis for several randomized trials. After the TIMI 9A, GUSTO Ila, and HIT 3 trials that tested hirudin as an adjunct to fibrinolytic therapy were... 

Timely measurements of blood and urine concentrations for suspected intoxicants are useful in guiding clinical therapy, especially when there is toxicity associated with the treatment agents. Unfortunately, analysis of cyanide in biological fluids is a difficult task for a variety of reasons.37 Also, measurements of blood cyanide concentrations are almost never available during the treatment phase. Blood concentrations of cyanide and associated clinical effects are shown in Table 10-3. 

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