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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].
Nursing, monitoring and transport of the sick neonate
Published in Janet M Rennie, Giles S Kendall, A Manual of Neonatal Intensive Care, 2013
Janet M Rennie, Giles S Kendall
The correct shorthand for a pulse oximeter reading is SpO2. Pulse oximetry is easy to use, requires no calibration and gives immediate information. The technique has revolutionized oxygen monitoring and is extremely valuable during resuscitation. Oximetry estimates the percentage oxygen saturation of haemoglobin in arterial blood (SpO2), not the partial pressure of oxygen (PaO2); it is not the same as true saturation (SaO2) measured in vitro with a co-oximeter. The technique of oximetry is dependent on the differential absorption of red (circa 660 nm) and infra-red (circa 940 nm) light by deoxyhaemoglobin and oxyhaemoglobin, respectively.
Correlation of refractory hypoxemia with biochemical markers and clinical outcomes of COVID-19 patients in a developing country: A retrospective observational study
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Muhammad Sohaib Asghar, Iftekhar Ahmed, Haris Alvi, Sadia Iqbal, Ismail Khan, Rabia Seher Alvi, Zara Saeed, Saboohi Irfan, Maria Akhtar, Ibraj Fatima
There were a few limitations of our study, we did not utilize the measurement of oxygen saturation of arterial blood gases as a partial oxygen pressure (arterial PaO2) but instead as pulse oximetry. PaO2 should be cautiously interpreted as measured by pulse oximetry [38]. Estimated CO-oximeter oxygen saturation (SpO2) may be roughly ±4% distinct from recorded arterial oxygen saturation. The validation of findings using calculated arterial oxygen saturation may also be a stronger criterion. Furthermore, to be able to accurately determine the lung potential for gas exchange, it is important to know the fraction of inspired oxygen (FiO2), which was not utilized in our study [40]. We solely relied on measurements by pulse oximeter to determine hypoxemia. Lastly, the biomarkers were evaluated in hospitalized patients and thus results cannot be generalizable to patients with milder COVID-19 disease who do not require hospitalization.
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.