0071643192.pdf

■ Hyperkalemic normal gap acidosis:
■ Adrenal insufficiency
■ Renal insufficiency
■ Posthypocapnia
■ Increased anion gap [Na+−(K++Cl−)]> 20
■ Causes of a high anion gap acidosis can be remembered with the
MUDPILES mnemonic.
■ For patients with a high anion gap without obvious identifiable cause,
such as DKA, lactic acidosis, or known ingestion, calculating a serum
osmolar gap is a screen for the presence of toxic alcohols. See “Fluids”
for a more detailed explanation.

TREATMENT

Treating the underlying cause is the most important action.

■ Sodium bicarbonate treatment is a controversial and potentially dangerous
treatment because of the risk of electrolyte disturbances and paradoxical cere-
bral acidosis. The cerebral acidosis occurs 2°to the inability of HCO 3 −to
quickly cross the blood-brain barrier. Bicarbonate for the treatment of acidosis
should only be considered for extremely ill patients with severe acidosis.
■ A brief reminder of some special treatments of underlying causes of meta-
bolic acidosis includes:
■ Ethylene glycol and methanol: Ethanol or 4-methylpyrazole and dialysis
■ Salicylate toxicity: HCO 3 −to keep serum pH between 7.3 and 7.5 with
resultant urine alkalinization; dialysis
■ Iron overdose: Deferoxamine
■ Isoniazid: Pyridoxine (vitamin B 6 )

Metabolic Alkalosis (↑pH + ↑HCO 3 −)

CAUSES

Increased bicarbonate usually occurs in the setting of:

■ Gastric acid loss from vomiting or NG suctioning
■ Diuretic use
■ Adrenocrotical hormone excess

DIAGNOSIS

Diagnosisof type can be categorized as:

■ Chloride (saline) sensitive (most common)
■ Diuretic or GI losses of K+and Cl−→responds to replacement.
■ Chloride (saline) resistant
■ Mineralocorticoid excess →renal absorption of Na+and HCO 3 −and
excretion of K+, H+, and Cl−→large K+replacement required.

Respiratory Acidosis (åpH + åHCO 3 - )

CAUSES

Primarily caused by inadequate ventilation or increased dead space. Causes
include:

■ Head or chest trauma
■ Oversedation, obtundation, or coma
■ Neuromuscular disorders

ENDOCRINE, METABOLIC, FLUID, AND

ELECTROLYTE DISORDERS

Measure the serum osmolar

gap to screen for toxic alcohol

ingestion in patients with AMS

and an increased anion gap.

Normal rate is <10 mOsm/L.