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The Toxic Environment and Its Medical Implications with Special Emphasis on Smoke Inhalation
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Jacob Loke, Richard A. Matthay, G. J. Walker. Smith
In laboratory studies, arterial blood gas analysis has revealed a near normal arterial oxygen tension (PaO2) and a metabolic acidosis with increased serum lactate (Buehler et al., 1975;Landa et al., 1972). Anticoagulated whole blood should be obtained to determine the blood carboxyhemoglobin (COHb) level. The COHb level is valuable in assessing the severity of acute smoke inhalation. Hemoglobin and methemoglobin are other parameters that can be measured when the blood carboxyhemoglobin level is obtained using the CO-Oximeter analyzer. Patients with elevation in COHb may have a normal Pa02 and a normal calculated oxygen saturation (Eckfeldt, 1978). However, the measured arterial oxygen saturation and arterial oxygen content will both be decreased. In a patient who has arterial hypoxemia, as well as a reduced measured oxygen saturation, the lung inhalation injury may be more severe than in an individual who has a reduction in measured arterial oxygen saturation and a normal PaO2. Falsely elevated values of blood hemoglobin and carboxyhemoglobin can occur in patients with markedly increased levels of triglycerides and chylomicrons (Hodgkin and Chan, 1975).
Leprosy: Therapy-related emergencies
Published in Biju Vasudevan, Rajesh Verma, Dermatological Emergencies, 2019
Diagnosis of methemoglobinemia is normally based on characteristic clinical symptoms and raised serum methemoglobin level. Serum methemoglobin levels are not routinely available in a resource-poor setup. Therefore, the typical oxygen “saturation gap” observed between arterial blood gas analysis and pulse oximetry readings is very helpful for making the diagnosis of methemoglobinemia. Once other forms of hemoglobin such as methemoglobin rise, the oxygen saturation on pulse oximetry falls and plateaus at 85%. This situation, where oxygen saturation levels measured with pulse oximetry are substantially lower than arterial blood gas oxygen saturation levels, should alarm the treating physician. Also, in cases of methemoglobinemia, arterial blood samples will have a typical chocolate-brown color (Figure 59.3) [28,29]. Since its advent, the carbon monoxide (CO) oximeter has become the gold standard in diagnosing methemoglobinemia [29].
Gases
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
The clinical presentation of CO poisoning depends on the time of exposure and the concentration of CO in the area, as noted previously. Acute, high-concentration exposure, such as might occur in an enclosed space (automobile exhaust in a closed garage), will produce more severe signs and symptoms than chronic, low-concentration exposure (as with faulty heating systems). The latter scenario may be misdiagnosed as mimicking a bacterial or viral infection. Symptoms from acute, mild exposure range from asymptomatic to headache, dizziness, malaise, and fatigue. Moderate exposure may present with confusion, lethargy, ataxia, syncope, and nystagmus.* Severe intoxication manifests as seizures, pulmonary edema, myocardial infarction, and coma. The classic cherry-red discoloration of the face and extremities, due to uncompensated peripheral vasodilation, is evident only in severe poisoning. Blood samples for gas analysis must be obtained immediately after exposure (using blood gas CO-oximetry). The calculation of percentage of arterial blood oxyhemoglobin (SaO2), based on blood gas analysis, is often falsely elevated because of COHb high-affinity binding. Other routine clinical laboratory values may also lead to inaccurate conclusions.
Cyanosis, hemolysis, decreased HbA1c and abnormal co-oximetry in a patient with hemoglobin M Saskatoon [HBB:c.190C > T p.His64Tyr]
Published in Hematology, 2021
Eva-Leonne Göttgens, Kristian Baks, Cornelis L. Harteveld, Kristel Goossens, Adriaan J. van Gammeren
Due to the cyanotic appearance and indication of low oxygen saturation by a portable finger pulse-oximeter (Beurer), methemoglobin analysis was performed. The blood gas analyser (Siemens Rapidpoint500) indicated abnormal spectral absorbance and issued a warning for methemoglobin. Quantitation of methemoglobin could not be performed. Co-oximetry analysis was also performed using a second blood gas analyser (Radiometer ABL90 Flex Plus). This instrument also could not detect oxygen saturation or methemoglobin values, because of interference attributed to the presence of unstable methemoglobinemia. In a previous case of a patient carrying the Hb M Hyde Park variant, in which the histidine residue at position 92 of the β-globin chain has been substituted by a tyrosine residue, which is at the opposite (proximal) side of the porphyrin ring compared to the Hb M Saskatoon, methemoglobin also could not be detected [23]. This observation indicates that unstable Hb M variants interfere with absorption spectra of stable variants in blood gas co-oxymetry, disabling the measurements of the of stable hemoglobins, like oxyHb (OHb), deoxyHb (HHb), carboxy Hb (COHb) and stable methemoglobin (metHb) [24].
Carbon monoxide poisoning from waterpipe smoking: a retrospective cohort study
Published in Clinical Toxicology, 2018
Lars Eichhorn, Dirk Michaelis, Michael Kemmerer, Björn Jüttner, Kay Tetzlaff
In our cohort, there were a substantial number of cases in whom COHb levels had been measured on site by noninvasive pulse CO-oximetry. CO pulse oximetry can be used for screening [55], but it’s limited reliability and accuracy require the presence of patients’ history or clinical signs of CO poisoning [56]. We did not find a close correlation between COHb values and the initial symptoms, whether measured noninvasively or by venous blood gas analysis. However, we could find that a higher number of syncope was associated with high COHb levels. Symptoms may be mild or even not present as in three subjects in our study. Thus, CO poisoning may be largely under-reported, and it is tempting to speculate that patients with mild or temporary unspecific symptoms might not have called an ambulance. Although waterpipe smoking is quite popular, the actual number of case reports in the literature is scarce. In our cohort, the most common symptoms [i.e. syncope (n = 46), dizziness (n = 38) and headache (n = 35)] were prevalent amongst referred patients with the majority of cases having two or more symptoms.
Reliability of transcutaneous hemoglobin measurements in an outpatient pediatric clinic
Published in Postgraduate Medicine, 2022
Shae Margulies, Molly Posa, Melissa Fitzgerald, Stephanie Filipp, Diane Howell, Puneet Tung, Maria Kelly
This quality improvement study was implemented at one University of Florida (UF) Health outpatient pediatric clinic between July 2019 and June 2020. Institutional Review Board (IRB) approval was waived as the study was entered into the institution’s Quality Improvement Project Registry (QIPR). All patients in a single pediatric outpatient clinic were eligible to be screened for anemia via both methodologies when clinically indicated. When screening for anemia, obtaining a capillary point-of-care hemoglobin measurement is standard of care for children at this pediatric clinic. All clinic staff (nurses and pediatric providers) were trained on how to properly use the Pronto Pulse Co-Oximeter in order to obtain accurate hemoglobin readings. They were encouraged to utilize both methods for all patient hemoglobin measurements in order to obtain comparison data. Following the one-year study period, a list of medical record numbers (MRN) for all pediatric patients that concurrently received both a transcutaneous and standard of care capillary hemoglobin measurement during an office visit was obtained from the electronic medical record (EMR). The list included all patients where both methodologies were attempted regardless of whether a result was successfully obtained or not. A chart review was conducted and additional patient data was extracted for comparison. Basic patient demographics, the presence of co-morbid conditions, and both transcutaneous and capillary hemoglobin measurements were entered into a Research Electronic Data Capture (REDCap) database following the chart review [11,12]. REDCap is a web-based research tool with a user-friendly interface that allows for validation of fields promoting rigorous data collection.