Abstract
An asymptomatic 81-year-old woman was referred by her general practitioner regarding a pulse-oximetry oxygen saturation (SpO2) of 74%. An arterial blood gas analysis (ABG) on air showed PaO2 12.9 kPa, oxygen saturation 80%, with normal pH, PaCO2, methaemoglobin and carboxyhaemoglobin levels. After a normal chest x-ray, tinzaparin was administered empirically for possible occult pulmonary embolus. This diagnosis was subsequently excluded with an unremarkable computed tomography pulmonary angiogram (CTPA). She was further investigated as an out patient. DNA globin-gene analysis identified a variant haemoglobin revealed to be haemoglobin Saint Mande (HbSM). Following reassurance regarding the benign nature of her condition, she has remained well.
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References
- Arous N, Braconnier F, Thillet J, et al. Hemoglobin Saint Mandé beta 102 (G4) asn replaced by tyr: a new low oxygen affinity variant. FEBS Letters. 1981; 126(1): 114–116.
- Verhovsek M, Henderson M, Cox G, et al. Unexpectedly low oximetry measurements associated with variant hemoglobins: A systematic review. American Journal of Hematology. 2011; 85(11):882–885.
- Nagel RL. Disorders of Hemoglobin Function and Stability. In Steinberg MH. et al. Disorders of Hemoglobin: Genetics, Pathophysiology, and Clinical management. 2nd ed. Cambridge University Press, 2009.
- Kutlar F, Unguru Y, Dixon N, et al. Two New Hemoglobin Variants: Hb Tallahassee [α3(A1)Ser Tyr; HbA2: c. 11C>A] and Hb Madison-NC [β119 (GH2) Gly Ser; HBB: c. 358G>A].Hemoglobin. 2014; 38(3): 207–210.
- Bonaventura J. & Riggs A. Hemoglobin Kansas, a human haemoglobin with a neutral amino acid substitution and an abnormal oxygen equilibrium. The Journal of Biological Chemistry. 1968; 243: 980.
- Nagel RL, Lynfield J, Johnson J, et al. Hemoglobin Beth Israel. A mutant causing clinically apparent cyanosis. New England Journal of Medicine. 1976; 295: 125.
- Feller-Kopman D. & Schwartzstein R. The role of hypoventilation and ventilation perfusion redistribution in oxygen-induced hypercapnia during acute exacerbations of chronic obstructive pulmonary disease. American Journal of Respiratory & Critical Care Medicine 2001; 163: 1755.
- Downs JB. Has oxygen administration delayed appropriate respiratory care? Fallacies regarding oxygen therapy. Respiratory Care 2003; 48: 611–20.
- Thomson AJ, Webb DJ, Maxwell SR, et al. Oxygen therapy in acute medical care. British Medical Journal 2002; 324: 1406–7.
- Rehman HU. Methaemoglobinaemia. Western Journal of Medicine. 2001; 175(3): 193–196.
- Chan ED, Chan MM, & Chan MM. Pulse oximetry: Understanding its basic principles facilitates appreciation of its limitations. Respiratory Medicine 2013; 107(6): 789–799
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