Internal Medicine

0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:16

980 Metabolic Alkalosis Methemoglobinemia

complications and prognosis

■prognosis generally related to etiology of metabolic alkalosis

■metabolic alkalosis can contribute to mortality under certain cir-

cumstances

■increased pH can lead to respiratory depression, vasoconstriction of

coronary and cerebral circulation, and cause tissue hypoxia

■metabolic alkalosis in the setting of low EABV is generally reversible

with therapy and has a good prognosis

■with mineralocorticoid excess syndromes chronic therapy may be

required when underlying cause cannot be corrected, correction of

hypertension is critical

METHEMOGLOBINEMIA

XYLINA GREGG, MD and JOSEF PRCHAL, MD

history & physical

History

■Clinical suspicion when cyanosis occurs in presence of normal PaO2

■Acquired – Acute toxic

➣Most common form

➣Exposure to local anesthetics, oxidants – antifreeze, acetami-

nophen, many others

Persons heterozygous for cytochrome b5 reductase deficiency

may develop after exposure to agents harmless to normal indi-

viduals in

➣Infants – developmentally decreased cytochrome b5 reductase

activity

Occurs after diarrheal illness or exposure to nitrate-containing

well water

➣Symptoms related to impaired tissue O2 delivery

Early – headache, SOB, lethargy

Late – respiratory depression, altered consciousness, seizures,

death

■Chronic, congenital

➣Cyanotic, but usually asymptomatic; may develop compensatory

polycythemia

➣However, type 2 cytochrome b5 reductase deficiency (defect

not restricted to erythrocytes) associated with neurological syn-

drome/failure to thrive