Fluid restriction

P. Marsh, G. Rickayzen, M. Calleja. The structure of a hard sphere fluid restricted by permeable walls. Mol Phys 54 799, 1995. 

Fluid restriction not necessary unless serum sodium <120-125 mEq/L... 

Regardless of volume status, treat with 0.9% or 3% saline see below) until signs and symptoms resolve ° The patient can be placed on fluid restriction once signs and symptoms have resolved... 

Fluid restriction to between 1000 and 1200 mL/d ° Utilize a loop diuretic... 

Nonpharmacologic treatment involves dietary modifications such as sodium and fluid restriction, risk factor reduction including smoking cessation, timely immunizations, and supervised regular physical activity. 

Educate the patient on lifestyle modifications such as salt restriction (maximum 2 to 4 grams per day), fluid restriction if appropriate, limitation of alcohol, tobacco cessation, participation in a cardiac rehabilitation and exercise program, and proper immunizations such as the pneumococcal vaccine and yearly influenza vaccine. 

Adequate fluid intake is also important the recommended intake for people who do not require fluid restriction is 6 to 8 eight-ounce glasses of water daily. 

Fluid restriction is generally unnecessary as long as sodium intake is controlled. The thirst mechanism remains intact in CKD to maintain total body water and plasma osmolality near normal levels. Fluid intake should be maintained at the rate of urine output to replace urine losses, usually fixed at approximately 2 L/day as urine concentrating ability is lost. Significant increases in free water intake orally or intravenously can precipitate volume overload and hyponatremia. Patients with stage 5 CKD require renal replacement therapy to maintain normal volume status. Fluid intake is often limited in patients receiving hemodialysis to prevent fluid overload between dialysis sessions. 

Hypotonic hyponatremia with an increase in ECF is also known as dilutional hyponatremia. In this scenario, patients have an excess of total body sodium and TBW however, the excess in TBW is greater than the excess in total body sodium. Common causes include CHF, hepatic cirrhosis, and nephrotic syndrome. Treatment includes sodium and fluid restriction in conjunction with treatment of the underlying disorder—for example, salt and water restrictions are used in the setting of CHF along with loop diuretics, angiotensin-converting enzyme inhibitors, and spironolactone.15... 

Patients who experience encephalopathy, severe hyponatremia despite fluid restriction, or renal insufficiency should have diuretic therapy discontinued. 

More concentrated CAA solutions (i.e., 15% to 20%) are attractive for patients who have large protein needs, such as the critically ill, but are fluid restricted. 

Peripheral PN (PPN) is a relatively safe and simple method of nutritional support. PPN candidates do not have large nutritional requirements, are not fluid restricted, and are expected to begin enteral intake within 10 to 14 days. 

Patient case A patient s daily nutritional requirements have been estimated to be 100 g protein and 2,000 total kcal. The patient has a central venous access and reports no history of hyperlipidemia or egg allergy. The patient is not fluid restricted. The PN solution will be compounded as an individualized regimen using a single-bag, 24-hour infusion of a 2-in-1 solution with intravenous fat emulsion (IVFE) piggybacked into the PN infusion line. Determine the total PN volume and administration rate by calculating the macronutrient stock solution volumes required to provide the desired daily nutrients. The stock solutions used to compound this regimen are 10% crystalline amino acids (CAA), 70% dextrose, and 20% IVFE. 

Patients with hypervolemic hypotonic hyponatremia should be treated with 3% saline and prompt initiation of fluid restriction. Loop diuretic therapy will also likely be required to facilitate urinary excretion of free water. 

Watchful waiting involves reassessment at yearly intervals. Patients should be educated about behavior modification such as fluid restriction before bedtime, avoiding caffeine and alcohol, frequent emptying of the bladder, and avoiding drugs that exacerbate symptoms. 

Lab test abnormalities Serum sodium levels less than 125 mmol/L have been observed in patients treated with oxcarbazepine. Experience from clinical trials indicates that serum sodium levels return toward normal when the oxcarbazepine dosage is reduced or discontinued or when the patient was treated conservatively (eg, fluid restriction). 

Hyponatraemia impaired excretion of water and enhanced sodium retention is a feature of advanced cirrhosis. Fluid restriction is often imposed, but does not reverse the problem. Administration of hypertonic saline will exacerbate fluid retention. 

Since the effectiveness of many diuretics ultimately depends on establishing a negative Na balance to mobilize edema fluid, restriction of dietary Na intake is generally an essential part of diuretic therapy. Therefore, one cause of therapeutic failure or apparent patient refractoriness to diuretics could be the patient s continued ingestion of large quantities of NaCl. 

Behavioral therapies are the treatment of choice for enuresis in both typically developing children and children with MR. No medical intervention should be undertaken before considering behavioral interventions, such as a star chart for dry nights, evening fluid restriction, bladder-stretching exercises (where children are asked to hold their urine for as long as they can, past the initial bladder spasm), and/or the buzzer-and-pad. However, some MR/DD patients will be unable to cooperate with such strategies and may need medical... 

The mainstay of medical treatment is fluid restriction, but this may not be appropriate in the surgical and critical care patient population. Severe (<120 mmol-L-l) or symptomatic hyponatraemia (mental status changes, seizure) requires more aggressive therapy to reduce cerebral oedema. Infusion of hypertonic saline to increase plasma sodium concentrations to 120-125 mmol L-1 alleviates symptoms. Adjunct therapy with demeclocycline (600 mg-day-1) may assist management in resistant SIADH. Demeclocycline is a tetracycline antibiotic which inhibits the actions of ADH at the renal tubules. 

A 63-year-old man reduced his dietary sodium intake to combat fluid retention and was taking furosemide 40 mg/ day, spironolactone 50 mg/day, and enalapril 2.5 mg/day (26). He then took amiodarone 800 mg/day for 7 days and his serum sodium concentration fell to 119 mmol/1 his plasma vasopressin concentration was raised at 2.6 pmol/1. The dose of amiodarone was reduced to 100 mg/day, with fluid restriction his sodium rose to 130 mmol/1 and his vasopressin fell to 1.4 pmol/1. 

A 67-year-old man, who had taken amiodarone 200 mg/ day for 3 months, developed hyponatremia (serum sodium concentration 117 mmol/1) (27). He was also taking furosemide 20 mg/day, spironolactone 25 mg/ day, and lisinopril 40 mg/day. His urine osmolality was 740 mosmol/kg with a normal serum osmolality. Fluid restriction was ineffective, but when amiodarone was withdrawn the sodium rose to 136 mmol/1. 

Fluid restriction is advisable to reduce the risk of fluid overload in the intrapartum and postpartum periods. Total fluids should be limited to 80 mL/h or 1 mL/kg per hour. Pulmonary oedema has been associated with inappropriate fluid management. There is no benefit of fluid expansion it may increase the risk of caesarean section. The regimen of fluid restriction should be maintained until there is a postpartum diuresis as oliguria is common with severe preeclampsia. 

Mr KT should be advised to reduce his weight and reduce his alcohol intake. He should restrict his intake of red meats and food with a high purine content (e.g. meat extracts, kidney, liver, crab, anchovies, mackerel and sardines) and he should aim to increase his fluid intake to about 2 litres per day (assuming that he is not fluid restricted). 

Factors that put patients at risk of lithium intoxication are those that increase intake (deliberately or accidentally), reduce excretion (kidney disease, dehydration, low sodium intake, drug interactions), or reduce body water (dehydration secondary to fluid restriction, vomiting, diarrhea, or polyuria) (66). Patients with lithium-induced polyuria are at a particular risk of toxicity if their ability to replace fluids is compromised (for example by anesthesia, over-sedation, CNS trauma). 

Patients unable to take sufficient fluids orally require fluid by nasogastric tube or intravenous hydration. Hyponatremia, probably reflecting salt wasting and the stress response, is particularly common after subarachnoid hemorrhage and, in general, should be treated by plasma volume expansion and not fluid restriction. Urinary tract infection and dehydration may cause renal failure. 

Secondary ischemia is a frequent complication after SAH and is responsible for a substantial proportion of patients with poor outcome. The cause of secondary ischemia is unknown, but hypovolemia and fluid restriction are important risk factors. Hypovolemia should be avoided and intravenous fluids given, at least 3 liters per day, to reduce the likelihood of delayed ischemia. Indeed, volume expansion therapy is frequently used in patients with SAH to prevent or treat secondary ischemia. However, the risks and benefits of volume expansion therapy have been studied properly in only two trials of patients with aneurysmal SAH, with very small numbers (Rinkel et al. 2004). At present, there is no good evidence for the use of volume expansion therapy in patients with aneurysmal SAH. 

Peripheral PN (PPN) is a relatively safe and simple method of nutritional support. PPN candidates do not have large nutritional requirements, are not fluid restricted, and are expected to begin enteral intake within lOto 14days. Thrombophlebitis is a common complication this risk is greater with solution osmolarities greater than 600 to 900 mOsm/L (Table 60-2). Solutions for PPN have lower final concentrations of amino acid (3% to 5%), dextrose (5% to 10%) and micronutrients as compared to central parenteral nutrition (CPN). 

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