What are the three possible causes of methemoglobinemia?
People have developed methemoglobinemia after having medical procedures that used certain topical anesthetics that are often sprayed on to the skin. These include benzocaine, lidocaine, and prilocaine.
Which drug can cause methemoglobinemia?
Drugs that may cause Methemoglobinemia include nitrates derivatives (nitrates salt, nitroglycerin), nitrites derivatives (nitroprusside, amyl nitrite, nitric oxide), sulfonamides, dapsone, phenacetin, phenazopyridine, some local anesthetics such as prilocaine, topical anesthetics such as emla cream, benzocaine.
What can cause methemoglobinemia?
| Methemoglobinemia | |
|---|---|
| Causes | Benzocaine, nitrates, dapsone, genetics |
| Diagnostic method | Blood gas |
| Differential diagnosis | Argyria, sulfhemoglobinemia, heart failure |
| Treatment | Oxygen therapy, methylene blue |
Which of the following is most likely to cause methemoglobinemia?
The most common cause of congenital methemoglobinemia is cytochrome b5 reductase deficiency (type Ib5R). This enzymatic deficiency is endemic in certain Native American tribes (Navajo and Athabaskan Alaskans). Most cases of methemoglobinemia are acquired and result from exposure to certain drugs or toxins.
What is the cure for methemoglobinemia?
Methylene blue is used to treat severe cases of MetHb, and doctors may prescribe ascorbic acid to reduce the level of methemoglobin in the blood. In severe cases, a person may require a blood transfusion or exchange transfusion. Oxygen therapy will also be provided, if required.
What are the chances of getting methemoglobinemia?
Conclusions and relevance: The overall prevalence of methemoglobinemia is low at 0.035%; however, an increased risk was seen in hospitalized patients and with benzocaine-based anesthetics.
What is the antidote for methemoglobinemia?
Methylene blue is the most effective antidote for acquired methemoglobinemia. When methylene blue is not available, alternative treatments such as ascorbic acid and hyperbaric oxygen can be useful.
How does vitamin C treat methemoglobinemia?
Vitamin C is recommended for treatment of methemoglobinemia. It has been demonstrated that the reduction of the methemoglobin formation occurs at low vitamin C concentration in mice erythrocytes.
Can novocaine cause methemoglobinemia?
Methemoglobinemia is a potentially severe complication of lidocaine and benzocaine, especially when used concomitantly. Among the acquired causes of methemoglobinemia, although caine-induced methemoglobinemia is rare, it may have a fatal outcome.
Why is ascorbic acid used in the treatment of methemoglobinemia?
Ascorbic acid is an antioxidant and coenzyme for reduction. It may be helpful in the treatment of congenital methemoglobinemia if used daily and on a continual basis.
How is methemoglobinemia diagnosed?
The diagnosis is confirmed by direct measurement of methemoglobin by a multiple wavelength co-oximeter. On a blood gas, normal PaO2 concentrations are usually found on analysis. Clinical cyanosis in the presence of normal arterial oxygen tensions is highly suggestive of methemoglobinemia.
How is methemoglobinemia treated?
What happens to ferric hemoglobin in toxicokinetics?
Toxicokinetics Methemoglobinemia secondary to toxic exposures occurs when cytochrome-b5 reductase’s ability to reduce ferric hemoglobin, or methemoglobin, is overwhelmed by the induced oxidant stress. The result is increasing concentrations of methemoglobin leading to methemoglobinemia.
How are free radicals acquired in methemoglobinemia?
The free radicals that cause methemoglobinemia are most usually acquired through environmental exposure, or by ingestion of certain medications or dietary elements. In methemoglobinemia, oxidation of the iron in hemoglobin from the ferrous state (Fe ++) to the ferric state (Fe +++) forms methemoglobin.
How is methemoglobinemia a life-threatening condition?
Methemoglobinemia – StatPearls – NCBI Bookshelf Methemoglobinemia is a condition with life-threatening potential in which diminution of the oxygen-carrying capacity of circulating hemoglobin occurs due to conversion of some or all of the four iron species from the reduced ferrous [Fe2+] state to the oxidized ferric [Fe3+] state.
How is the percentage of methemoglobin calculated?
Percentage of methemoglobin is calculated by dividing the concentration of methemoglobin by the concentration of total hemoglobin. Percentage of methemoglobin is likely a better indicator of illness severity than overall concentration, as underlying medical conditions play an important role.