Fluids, Electrolytes, Acid-Base Disorders, and Nutrition Support

ECF volume

status

Hypervolemic

Euvolemic

Hypovolemic

Physiologic

Findings

Edema, large positive

fluid balance, pulmonary

infiltrates without pneu-

monia, enlarged heart,

increased PCWP, EDVI

No evidence of fluid overload or

dehydration, fluid equilibrium,

normal hemodynamics

Poor skin turgor, dry mucous

membranes, decreased urine

output, concentrated urine,

tachycardia, increased BUN/SCr

ratio

Urine Osm

(mOsm/kg)

> 100

< 100

> 100

> 450

Urine Na

(mEq/L)

< 20

>20

< 20

> 20

< 20

>20

Potential

etiologies

CHF,

Cirrhosis

with

ascites,

Nephrotic

syndrome

Renal

failure

Psychogenic

polydipsia,

Excessive

hypotonic fluid

intake,

Beer potomania

SIADH,a

Cortisol

deficiency,

Hypothyroidism,

Drug-induced

Extra-renal

losses (e.g.,

GI fluid

losses), Third

space losses

Diuretics,

Adrenal

insufficiency,

Cerebral

salt wasting,

Thiazide

diuretics,

Salt wasting

nephropathy

Central nervous system (CNS) disorders – Trauma, stroke, infection, brain tumors

Malignancy – Small cell carcinoma of the lung, pancreatic carcinoma, lymphoma, Hodgkin disease, sarcoma

Pulmonary infection, respiratory failure with positive pressure ventilation

Endocrine disorders – Pituitary tumor, hypothyroidism, adrenal insufficiency

Stress response (surgery, trauma, thermal injury, sepsis, pain)

Drugs

BUN=blood urea nitrogen; CHF = congestive heart failure; EDVI = end-diastolic volume index; GI = gastrointestinal; PCWP = pulmonary capillary wedge pressure;

SIADH = syndrome of inappropriate antidiurestic hormone.

Mechanism

Examples

Increased hypothalamic production

of ADH

Amitriptyline, imipramine

Thioridazine, trifluoperazine

Haloperidol

Carbamazepine, oxcarbazepine, valproic acid

Vincristine, vinblastine, cisplatin, carboplatin, ifosfamide, methotrexate

Nicotine

Bromocriptine

Monamine oxidase inhibitors

Increased sensitivity to or

exogenous administration of ADH

DDAVP, desmopressin

Lamotrigine