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Spurious Hypoxia: Consideration of Hemoglobinopathies

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Spurious Hypoxia: Consideration of Hemoglobinopathies Central Annals of Pediatrics & Child Health Case Report *Corresponding author Stephanie Phillips DO, Department of Pediatric Hematology/Oncology, Medical University of South Spurious Hypoxia: Consideration Carolina, MSC 558, 135 Rutledge Ave, Cahrleston, SC 29425, USA, Tel: 843-792-1053, Email: Submitted: 05 October 2015 of Hemoglobinopathies Accepted: 04 December 2015 Published: 07 December 2015 1 2 3 Stephanie Phillips DO *, John Lazarchick , Michael Bowman and Copyright 4 Shayla Bergmann © 2015 Stephanie Phillips et al. 1 Department of Pediatric Hematology/Oncology, Medical University of South Carolina, OPEN ACCESS USA 2Department of Pathology and Laboratory Medicine, Medical University of South Keywords Carolina, USA • Unstable hemoglobin • Hemoglobinopathy 3Department of Pediatric Pulmonology, Medical University of South Carolina, USA • Hypoxia 4 Departnent of Pediatric Hematology/Oncology, Medical University of South Carolina, • Hemoglobin sabine USA • Hemoglobin aalborg Abstract The use of the pulse oximeter to estimate oxygen saturation has revolutionized monitoring capabilities in medicine. However, there can be circumstances in which there is a discordance between oxygen saturation measurements via pulse oximeter (SpO2) and actual arterial oxygen levels (PaO2). In these situations, there is a possibility the patient could have a variant hemoglobin as the etiology of this discordance. This finding is generally incidental, and the patients are asymptomatic. However, knowledge of these variants is crucial and may spare patients unnecessary medical investigations. In this case report, two patients with variant hemoglobins found to have low oxygen saturations via pulse oximeter are presented, both of who underwent extensive medical workup and prolonged hospital stays. ABBREVIATIONS oxygen saturation readings by pulse oximeter and yet have normal oxygen saturation levels when measured by arterial blood SpO2: Oxygen Saturation via pulse Oximeter; PaO2: Arterial Oxygen Level; paO2 Partial Pressure of Oxygen; ABG Arterial : : programming is based upon a normal oxygen-hemoglobin Blood Gas gas analysis. It’s important to remember that pulse oximeter INTRODUCTION dissociation curve. Therefore, in the circumstance of discordance The use of the pulse oximeter to estimate oxygen saturation between SpO2 and PaO2 measurements, it’s wise to consider the has revolutionized monitoring capabilities in medicine, and in possibility of a variant hemoglobin as the cause. In most cases, variantthis finding hemoglobinopathies is usually incidental is crucial and the and patients may spareare otherwise patients can alert healthcare professionals when something may have healthy and asymptomatic. Therefore, knowledge of these affectedsome realms the cardio-pulmonary is even referred to systems as the fifthand vitalprompt sign the [1]. need Its usefor present two patients with variant hemoglobins found to have low oxygenunnecessary saturations medical via investigations pulse oximeter, [3]. both In thisof whom case underwentreport, we because it does not require a blood draw which is likely to cause further investigation. In pediatrics, the pulse oximeter is crucial extensive medical workup and prolonge in respiratory pattern immediately changes the blood gas d hospital stays. crying and/or breath-holding in children. This perturbation Table 1: measurement of oxygen saturation via pulse oximeter (SpO2) has IntrinsicPotential Factors Factors Affecting ExtrinsicPulse Oximetry Factors Measurements. values, making accurate interpretation challenging. As a result, Hemoglobinopathies Nail Polish Methemoglobin Calibration Assumptions becomeHowever, the universal there are measure well documentedof arterial oxygen instances levels in(PaO2). which Environmental interference – ie the use of these devices to measure oxygen saturation may not Carbon Monoxide Poisoning excessive movement be accurate, including motion artifact, poor perfusion, venous Low amplitude pulse – ie hypotension, hypovolemia, situations, patients may be unexpectedly found to have low hypothermia pulsation and nail polish [2-5] (Table 1). In other unique Cite this article: Stephanie Phillips DO, Lazarchick J, Bowman M, Bergmann S (2015) Spurious Hypoxia: Consideration of Hemoglobinopathies. Ann Pediatr Child Health 3(10): 1093. Stephanie Phillips et al. (2015) Email: Central CASE PRESENTATION Case report 1 facility. During his hospitalization, he had an echocardiogram blood gas was obtained and showed a paO2 and spiral chest CT done which were both normal. An arterial A 7 year old previously healthy male presented to an outside clinically and remained asymptomatic with ofnormal 116 mmHg lung and an oxygen saturation of 98%. The patient continued to look well he was found to be hypoxic with an oxygen saturation in the clinic with a one-week history of cough. On initial evaluation, tocardiovascular do well and wasexaminations. discharged Hemoglobin home with closevariants follow were up withsent 80% range obtained via pulse oximeter. He was seen by his and were reported as 17.8% “other hemoglobin”. He continued pediatrician, and a chest x-ray was obtained after confirming hemoglobin cascade testing was sent to Mayo Clinic and returned outpatient pediatric hematology. At his outpatient follow up visit, bloodthe SpO2 gas (ABG)reading. was The done chest and x-ray showed was a reportedlypartial pressure normal. of Lung examination was also documented as normal. An arterial at that visit remained healthy and asymptomatic with normal as 9.6% hemoglobin Sabine. The patient was lost to follow up but lowoxygen SpO2 (paO2) readings of 93 were mmHg. obtained, Hemoglobin the patient electrophoresis was referred was to obtained in the office with results pending. After persistent DISCUSSIONexercise tolerance. ultimately had a three-week hospitalization for workup of this When patients present with low oxygen saturation readings, our hospital for further workup. The patient was admitted and hypoxia. During this time, he remained asymptomatic, denying it generally causes a lengthy list of possible etiologies to flood Theshortness patient of breath,was initially chest pain,admitted or increased to the pediatricwork of breathing.intensive However,the mind inof certain the healthcare situations, provider.the clinical From presentation pulmonary of theto Respiratory and cardiovascular examination remained normal. patientcardiovascular may be to discordant infectious disease,with the the readings list can obtainedbe quite extensive. on pulse care unit for the hypoxia. He had some minimal improvement of The modern pulse oximeter has been in use since the mid scan,his SpO2 pulmonary readings function on 8L oftests, supplemental and echocardiogram oxygen via performed, facemask. oximetry. During his hospitalization, he had multiple chest xrays, a chest CT 1970’s and has become an essential tool in estimating oxygen all of which were normal. The patient had consultations with obtained and was positive for human metapneumovirus and whilesaturations incredibly in patients useful, [5].the accuracyIts use can of providethese machines real-time, may non- be pulmonology and cardiology. A respiratory viral panel was mycoplasma pneumoniae limitedinvasive in assessments certain circumstances, of patients particularly oxygenation in status. cases whereHowever, the clinical appearance of the patient does not correlate with the . The patient was treated for atypical pneumonia with no improvement in oxygen saturations. An arterial blood gas analysis was done which showed a paO2 of 93 absorbancereadings. Carboxy- by using and 2 diodesdecarboxy-hemoglobin transmitting light have of differing mmHg and an oxygen saturation of 98%. did not improve following macrolide therapy, he was presumed wavelengthslight absorption across patterns. a tissue A topulse measure oximeter the intensitymeasures of thisthe to haveWhen macrolide-resistantthe patient’s oxygen mycoplasma saturations infectionvia pulse andoximeter was hemoglobin can then be derived using the known absorbance wavelengths at the other side. The percent oxygen saturation of caretreated physician with a ten-dayreturned course during of hisclindamycin. hospitalization The resultsshowing of the presence of a hemoglobinopathy, pulse oximetry alone may the hemoglobin electrophoresis done by the patient’s primary spectra of oxygenated and deoxygenated hemoglobin [5,6]. In despite persistent hypoxia measured by pulse oximeter and was circumstances, the hemoglobin molecule is altered often as a a hemoglobin variant. The patient remained asymptomatic not be reliable to accurately measure oxygen saturation. In these discharged home with 0.5L supplemental oxygen to use at night. result of an amino acid substitution that changes the molecule’s theHe hadpresence follow of upthe as hemoglobin an outpatient variant with and pediatric results showedhematology. 24% affinity for oxygen. Hemoglobin cascade testing was sent to Mayo Clinic to confirm In the first case reported above, the patient was found to have hemoglobin Aalborg. This rare hemoglobin variant is the hemoglobin Aalborg. The nighttime supplemental oxygen was patientsresult of anin argininegeneral residueare asymptomatic replacing glycine. and are As anot consequence, associated discontinued. The patient continues to do well despite incidental this unstable hemoglobin has a decreased oxygen affinity. These lowCase oxygen report saturations 2 on pulse oximetry. A 7-year-old male with a past medical history of hereditary
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