COMPLICATIONS
■ Overly aggressive correction of chronic hypernatremia can lead to cerebral
edema.
A patient with a history of renal failure missed her last few dialysis ses-
sions and presents with weakness. When attached to the cardiac monitor
you notice a very wide QRS complex resembling a sine wave. What treat-
ments should be initiated? Which of these treatments is definitive?
Initiate treatment with calcium, insulin with glucose, kayexalate, and dialy-
sis. Consider sodium bicarbonate and albuterol as adjuncts. Ultimately only
kayexalate and dialysis are definitive.POTASSIUM■ While 98% of K+is intracellular, serum K+is usually a good indicator of
total body stores.
■ Changes in intracellular/extracellular gradient assist propagation of electri-
cal impulses.
■ K+is freely filtered through the glomerulus, absorbed in the proximal and
ascending tubules, and secreted in the distal tubules through a Na+/K+gate.
Hypokalemia (K+<3.5 mEq/L)
SYMPTOMS
■ Nonspecific
■ Weakness
■ Abdominal distention
EXAM
■ Muscle weakness
■ Hyporeflexia in severe cases but DTRs usually preserved
■ Paralysis if severe, ie, hypokalemic periodic paralysis
■ Ileus
■ Cardiac findings: not sensitive, but see Figure 7.2
■ Bradycardia and AV block
■ VFib or V-Tach
■ U waves and flat T waves
■ ST depression if severe
■ QT prolongation if severe
DIFFERENTIAL
■ CVA
■ Infection
■ Primary neuromuscular disorders such as:
■ Amyotrophic lateral sclerosis
■ Guillain-Barré syndrome
■ Myasthenia gravis
■ Botulism
ENDOCRINE, METABOLIC, FLUID, ANDELECTROLYTE DISORDERS