Blood methemoglobin

Five workers at an Ohio rubber plant became ill with symptoms, including yellow discoloration of the hands, blue discoloration of the lips and nail beds, headache, nausea, chest pain, dizziness, confusion, and difficulty in concentrating one worker suffered a seizure." Medical examinations showed that blood methemoglobin levels ranged from 3.8% to 41.2%. Effects were attributed to dermal exposure to an adhesive containing 1% by weightp-DNB. After replacement of the adhesive, symptoms disappeared and methemoglobin levels were within normal limits. 

The nitrite-induced formation of blood methemoglobin has been used successfully to treat hydrogen sulfide poisoning. Like cyanide, hydrogen sulfide bonds to iron(III) in methemoglobin so that it is not available to inhibit cytochrome oxidase.15... 

Increased levels of blood methemoglobin have been reported in rats exposed to nitrobenzene at levels as low as 10 ppm for two weeks (Medinsky and Irons 1985) or 5 ppm for 90 days (Hamm 1984). 

The most important requirements for safe NO inhalation therapy include (I) continuous measurement of NO and NOj concentrations using either chemiluminescence or electrochemical analyzers (2) frequent calibration of monitoring equipment (S) intermittent analysis of blood methemoglobin levels (4) the use of certified tanks of NO and (5) administration of the lowest NO concentration required for therapeutic effect. 

Fig. 6.13 TOP MRA artifact. Blood (methemoglobin) in the prepontine cistern has high signal on the time of flight MRA (a) because signal from substances with short T1 is not adequately...

METHEMOGLOBIN INDUCERS Methemoglobin in blood During or end of shift 1.5% of haemoglobin B, Ns,... 

The oxides of nitrogen are somewhat sol in w, reacting with it in the presence of oxygen to form nitric and nitrous acids. This is the action that takes place deep in the respiratory system. The acids formed are irritants, causing congestion of the throat and bronchi, and edema of the lungs. The acids are neutralized by the alkalies present in the tissues, with the formation of nitrates and nitrites. The latter may cause some arterial dilation, fall in blood press, headache and dizziness, and there may be some formation of methemoglobin. However, the nitrite effect is of secondary importance... 

Blood transfusions may be indicated with methemoglobin levels >50% and evidence of tissue hypoxia... 

FIGURE 1—1 Formation and disappearance of methemoglobin from blood of rats exposed at 100 ppm for 8 or 12 h. Source Modified from Kim and Carlson 1986. 

In an in vitro study in which phenylhydroxylamine (0.5 milligram per milliliter (mg/ mL)) was added to samples of rat and human blood, blood from the human subjects produced less methemoglobin in the human subjects than in the rats (approximately 35% in human blood and 60% in rat blood) (Jenkins et al. 1972). There was no more variation in methemoglobin levels among the cells from different humans than among the cells from different rats. 

Mier (1988) reported on the ingestion of aniline by a 4.5-y-old child weighing 16 kg. Ingestion of approximately 1 teaspoon (approximately 0.3125 mg/kg) produced a methemoglobin level of 68% by 6 h after ingestion. At this time, treatment consisted of intravenous methylene blue to which she was poorly responsive followed by blood exchange 13 h after ingestion. 

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