Carboxyhemoglobin

Pulse oximeters are known to be inaccurate in the presence of elevated concentrations of carboxyhemoglobin and methemoglobin. This paper attempts to alleviate some of the confusion that exists between fractional and functional saturation, and to clarify the comparison of each with SpO2. A series of theoretical relationships between pulse oximeter reading (SpO2) and actual oxygen saturation (both fractional and functional) is derived using simple absorption theory. The theoretical relationships are checked using an experimental in vitro test system. This consists of a blood circuit containing a model finger, capable of simulating the pulsatile transmission signals through a real finger. Theoretical predictions and experimental results are compared and are found to agree well in the presence of carboxyhemoglobin, but less well with methemoglobin. Possible reasons are discussed.

Mainstream smoke (MS) from experimental kretek cigarettes with three ingredient mixes at low (typical use level) and high (2.5 or 3 times that level) inclusion rates was compared to a control kretek cigarette of identical construction (cloves and humectants), but without the addition of ingredients. 350 ingredients, commonly used in various combinations and in a limited number in a given brand in the manufacture of marketed kretek cigarettes were assessed. The MS composition of the kretek cigarettes was characterized by a comprehensive set of analytes (55 smoke constituents). Furthermore, the smoke was assessed in vitro for its cytotoxicity in the Neutral Red Uptake assay (particle phase and gas/vapor phase separately) in mouse embryo BALB/c 3T3 cells, and for mutagenicity/genotoxicity in the Salmonella typhimurium reverse mutation assay and the mammalian cell mouse lymphoma TK assay in L5178Y cells, the latter with and without metabolic activation. There were some statistically sig...

The Nrf2/heme oxygenase-1 (HO-1) axis affords significant protection against oxidative stress and cellular damage. We synthesized a series of cobalt-based hybrid molecules (HYCOs) that combine an Nrf2 inducer with a releaser of carbon monoxide (CO), an anti-inflammatory product of HO-1. Two HYCOs markedly increased Nrf2/HO-1 expression, liberated CO and exerted anti-inflammatory activity in vitro. HYCOs also up-regulated tissue HO-1 and delivered CO in blood after administration in vivo, supporting their potential use against inflammatory conditions.

The guideline 'Treatment of acute carbon-monoxide poisoning' from doctors in clinics with a tank for hyperbaric ventilation Carbon-monoxide (CO) poisoning is a potentially life-threatening emergency. Its prognosis is determined by prompt recognition and treatment. CO is toxic because it binds to haemoglobin (Hb), thus impairing oxygen transport and causing tissue hypoxia. The most important symptoms are headache and altered consciousness, ranging from somnolence to coma. The diagnosis is based on a history ofCO exposure combined with an elevated carboxyhaemoglobin (HbCO) level in the blood. On the basis of the available literature, it is recommended that patients with a HbCO level > or = 10% should always be treated. In patients requiring artificial ventilation, 100% oxygen for 8 hours is recommended. In pregnant women and in patients who are or have been comatose, hyperbaric oxygen can be considered. In all other symptomatic patients, use of a non-rebreathing mask with 1...

... Sean Hays Exponent Boulder, Colorado E-mail: shays@exponent.com ... Discovery of lead poisoning through a family pet has been previously reported (Dowsett and Shannon 1994), and some have suggested that pets are good sentinels for poisoning of children (Berny et al. ...

Hemolysis may contribute to hyperbilirubinemia in Gilbert's syndrome. The authors examined blood carboxyhemoglobin corrected for inspired CO (COHbc) to index heme catabolism and serum conjugated bilirubin fractions to reflect bilirubin conjugation. Both parameters were related to UDP-glucuronosyltransferase 1A1 (UGT) promoter polymorphism, associated with Gilbert's syndrome, in term male newborns. COHbc was expressed as percentage of total hemoglobin, and total conjugated

Fifteen men were exposed to 6,683 ppm C18O for 3.09-6.65 min. Arterial and antecubital vein blood samples were drawn at 1-min intervals beginning at the start of C18O inhalation and ending 10 min later. Simultaneously, alveolar ventilation was calculated from the measured values of minute ventilation and dead space. All other parameters of the Coburn-Forster-Kane equation (CFKE), except the Haldane affinity ratio, were measured separately in each subject. Means of CFKE predictions of increases in venous HbCO (delta HbCO) in samples collected approximately 2 min after cessation of exposure were accurate, but the range in errors of prediction for individual subjects was +/- 3.8% HbCO, depending on the time after exposure cessation. Increases in venous and arterial HbCO were inaccurately predicted during and immediately after HbCO formation, however. Venous blood was overestimated during CO uptake because of a delayed appearance of HbCO. Individual subjects differed markedly in the deg...

To evaluate serial cyanide, methemoglobin, and carbon monoxide levels in smoke inhalation patients. Regional poison center and regional toxicology treatment center. Seven critically ill smoke inhalation patients referred to the regional poison center. Peak level and half-life were determined by obtaining serial carboxyhemoglobin, cyanide, and methemoglobin levels. The mean observed half-life of cyanide was 3.0 +/- 0.6 hours. Methemoglobinemia was evaluated in four patients after sodium nitrite administration. The peak measured methemoglobin levels (mean, 10.5% +/- 2%; range, 7.9% to 13.4%) did not occur until a mean of 50 minutes (range, 35 to 70 minutes) following administration of sodium nitrite. The total oxygen-carrying capacity reduced by the combination of carboxyhemoglobin and methemoglobin was never more than 21% (range, 10% to 21%) in this series. The administration of sodium nitrite to smoke inhalation patients in the presence of concomitant carbon monoxide poisoning may be relatively safe.

To determine whether endogenous carbon monoxide levels in exacerbations of Chronic Obstructive Pulmonary Disease patients were higher compared to healthy individuals and to investigate alteration of carbon monoxide levels across the three different severity stages of Global Initiative for Chronic Obstructive Lung Disease criteria related to Chronic Obstructive Pulmonary Disease exacerbations. The prospective study was conducted from January to March 2011 at two medical institutions in Ankara, Turkey, and comprised patients of acute Chronic Obstructive Pulmonary Disease exacerbations. The severity of the exacerbations was based on the Global Initiative for Chronic Obstructive Lung Disease criteria. Patients with active tobacco smoking, suspicious carbon monoxide poisoning and uncertain diagnosis were excluded. healthy control subjects who did not have any comorbid diseases and smoking habitus were also enrolled to compare the differences between carboxyhaemoglobin levels A two-tailed...

OBJECTIVE: This retrospective study examined the correlation between carboxyhaemoglobin (COHb) levels and vital signs in patients with carbon monoxide (CO) intoxication. METHODS: Over a 10-year period, patients > 16 years of age who presented to the emergency department due to CO intoxication were included. Age, gender, comorbidities, month/year of presentation, presenting symptoms, vital signs, blood pH, COHb level, treatment and outcome were recorded. RESULTS: In total, 476 patients were included. The mean ± SD age was 36.22 ± 13.65 years; 96.4% of the patients had a normal Glasgow Coma Scale score, 91.0% had normal blood pressure and 80.0% had a normal heart rate. COHb levels were stratified into three groups: < 10% ( n = 39), 10 – 20% ( n = 106) and > 20% ( n = 205); levels could not be obtained in the remaining 126 patients. In patients with COHb levels > 20%, 34 (16.6%) had alkalosis and nine (4.4%) had acidosis. Among patients with COHb levels > 20%, 140 (68.3%...