883 Ⅵ CASE REPORTS Anesthesiology 2000; 93:883–4 © 2000 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Sulfhemoglobinemia Presenting as Pulse Oximetry Desaturation Nadarajah Aravindhan, M.B.B.S., M.R.C.P., F.R.C.A.,* David George Chisholm, M.B.B.S., M.R.C.P., F.R.C.A.† SULFHEMOGLOBIN is a rare cause of cyanosis that is pressure of oxygen (PO2) of 99 mmHg, with the patient breathing room usually drug induced. The effects of sulfhemoglobin on air. A diagnosis of methemoglobinemia was presumed, so the sampleDownloaded from http://pubs.asahq.org/anesthesiology/article-pdf/93/3/883/400717/0000542-200009000-00040.pdf by guest on 01 October 2021 pulse oximetry have not been reported widely. We was sent for analysis by hemoximeter (Chiron Rapidlab 865; Bayer Diagnostics, Tarrytown, NY). This showed a methemoglobin concen- present the case of a 48-yr-old woman who was sched- tration of 0.3% and a carboxyhemoglobin concentration of 0.3%, but a uled to undergo palliative surgery. Before anesthesia, she sulfhemoglobin concentration greater than 1.5%. Because the he- had an oxygen saturation, measured by pulse oximetry moximeter was able to indicate only the presence of sulfhemoglobin, rather than an absolute concentration, anesthesia was postponed for (SpO2), of 85%. This apparent desaturation subsequently was discovered to be the result of a blood sulfhemoglo- further investigation. A sample of arterial blood was analyzed by use of a manual assay bin concentration of 28%. She had been prescribed met- with a variable wavelength spectrophotometer (Cecil Series 2; Cecil oclopramide daily for more than 1 yr. Long-term inges- Instruments, Cambridge, UK); this showed a sulfhemoglobin concen- tion of metoclopramide is a cause of drug-induced tration of 28%.1 The patient’s surgery was planned for the week after sulfhemoglobinemia. blood transfusion. However, the patient decided against operative treatment. She was discharged to outpatient hospice care and declined further investigation of her sulfhemoglobinemia. Case Report Discussion The patient, a 48-yr-old woman with locally advanced carcinoma of the cervix, presented for palliative surgery for a rectovaginal fistula. At In the case described, the presence of significant pulse admission, she was being administered 100 mg slow-release morphine oximetry desaturation associated with a normal arterial (MST) twice a day and 25 mg amitriptyline at night. For the previous year, she had also been prescribed 10 mg metoclopramide three times oxygen tension (PaO2) alerted us to the possibility of an a day for persistent nausea and vomiting. At preoperative assessment, abnormal hemoglobin species interfering with the pulse her cardiorespiratory function was normal, although she was anemic, oximeter. Pulse oximeters use two light wavelengths with a hemoglobin concentration of 8.2 g/dl. (660 and 940 nm) to determine the ratio of pulse-added The patient was premedicated with 2 mg oral lorazepam 2 h preop- 2 absorbencies. This ratio is associated with SpO by eratively. At arrival in the operating room, a pulse oximeter (Hewlett 2 Packard 54S; Hewlett Packard, Avondale, CA) was connected to her. means of a table derived from data from healthy volun- Her SpO2 while breathing room air was recorded as 85%, with the teers. Dyshemoglobin molecules that have light absor- sensor on her index finger. At close observation, the patient was bance peaks at 660 or 940 nm affect the ratio of light cyanotic but not dyspneic. A radial arterial cannula was inserted, and absorbencies at these wavelengths and lead to spurious arterial blood was analyzed. Blood gas analysis (CIBA-Corning 288; SpO readings. Methemoglobin has significant absorben- CIBA-Corning Diagnostics, Medfield, MA) showed a pH of 7.41, a 2 cies at both of these wavelengths and has been reported partial pressure of carbon dioide (PCO2) of 38 mmHg, and a partial widely to interfere with pulse oximetry.3,4 Sulfhemoglo- bin has a greater absorbance at 660 nm than do oxyhe- * Specialist Registrar in Anesthesia. moglobin, deoxyhemoglobin, and methemoglobin.5,6 † Consultant Anesthetist. We could not find data relating to the absorbance of Received from the Department of Anesthesia, The Royal Marsden sulfhemoglobin at 940 nm. Therefore, it is difficult to Hospital, London, United Kingdom. Submitted for publication October predict how increasing concentrations of sulfhemoglo- 27, 1999. Accepted for publication April 21, 2000. Support was pro- vided by The Royal Marsden National Health Service Trust. bin might interfere with pulse oximetry. The effects of Address reprint requests to Dr. Chisholm: The Royal Marsden Hos- increasing concentrations of methemoglobin on pulse pital, Fulham Road, London SW3 6JJ, United Kingdom. Address elec- oximetry have been determined experimentally in tronic mail to: [email protected] dogs.4 There is no similar report available for sulfhemo- Individual article reprints may be purchased through the Journal globin, possibly because of the difficulty of inducing Web site, www.anesthesiology.org sulfhemoglobinemia in vivo. In a literature search, we Key words: Abnormal hemoglobin; cyanosis; monitoring. could find only two cases of sulfhemoglobinemia in Anesthesiology, V 93, No 3, Sep 2000 884 CASE REPORTS which the use of pulse oximetry was reported. The first Only 0.5 g/dl sulfhemoglobin is needed to cause clini- report described an SpO2 of 88%, with a sulfhemoglobin cally detectable cyanosis, as compared with 1.5 g/dl concentration of more than 1.5%, as indicated by he- methemoglobin and 5 g/dl deoxygenated hemoglobin.5 moximetry.7 Unfortunately, although the presence of Sulfhemoglobin cannot carry oxygen; however, high sulfhemoglobin was proven by gas chromatography, no concentrations of sulfhemoglobin are well-tolerated, de- absolute concentration was reported. The second report spite the resulting physiologic anemia. This is caused by described an SpO2 of 92–94%, with a sulfhemoglobin a right shift in the hemoglobin–oxygen dissociation concentration of 16%, as measured by spectrophotome- curve of the normal heme in the presence of sulfhemo- 8 Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/93/3/883/400717/0000542-200009000-00040.pdf by guest on 01 October 2021 try. This compares with an SpO2 of 85% associated with globin, thus facilitating tissue oxygenation. This is in a sulfhemoglobin concentration of 28%, as seen in the contrast to methemoglobin, which causes a left shift in current patient. the curve. This can result in severely impaired tissue Hemoximeters use multiple wavelengths to determine oxygenation at higher concentrations. There is no spe- concentrations of oxyhemoglobin, deoxyhemoglobin, cific treatment for sulfhemoglobinemia, other than re- carboxyhemoglobin, and methemoglobin. Some ma- moving the suspected cause. The concentration of sulf- chines do not distinguish between methemoglobin and hemoglobin decreases as erythrocytes are destroyed and sulfhemoglobin because of their similar absorption replaced. peaks.9 This has caused inappropriate treatment of sulf- hemoglobinemia with methylene blue.7 Some machines, The authors thank Mr. Desmond Barton and Mr. Jhangir Iqbal, The such as the Chiron Rapidlab 865, indicate the presence Royal Marsden Hospital, London, United Kingdom, for their help with of sulfhemoglobin but cannot quantify the concentra- this case report. tion. The laboratory measurement of sulfhemoglobin re- lies on an absorption peak at 620 nm, which, unlike References methemoglobin, persists after the addition of cyanide or dithionate.1 1. Tietz NW: Textbook of Clinical Chemistry. Philadelphia, WB Saunders, 1986, pp 1536–40 Sulfhemoglobinemia is recognized as a rare cause of 2. Pologe JA: Pulse oximetry: Technical aspects of machine design. 10 cyanosis, including intraoperative cyanosis. Sulfhemo- Int Anesthesiol Clin 1987; 25:137–53 globin is a stable, green-pigmented molecule that lasts 3. Eisenkraft JB: Pulse oximeter desaturation due to methemoglo- the lifetime of the erythrocyte. Certain drugs and chem- binemia. ANESTHESIOLOGY 1988; 68:279–82 icals cause oxidation of hemoglobin, which, with the 4. Barker SJ, Tremper KK, Hyatt J: Effects of methemoglobinemia on pulse oximetry and mixed venous oximetry. ANESTHESIOLOGY 1989; addition of a sulfur atom, forms sulfhemoglobin. The 70:112–7 most common drugs known to cause sulfhemoglo- 5. Finch CA: Methemoglobinemia and sulfhemoglobinemia. New binemia are phenacetin, dapsone, and the sulfonamides. Engl J Med 1948; 239:470–8 It has also been described with occupational exposure to 6. Siggard-Andersen O, Norgaard-Pedersen B, Rem J: Hemoglobin sulfur compounds and with drug abuse.11 Long-term pigments. Spectrophotometric determination of oxy-, carboxy-, met-, and sulfhemoglobin in capillary blood. Clin Chim Acta 1972; 42:85– metoclopramide ingestion has been reported as a cause 100 12 of sulfhemoglobinemia. Short-term high-dose metoclo- 7. Lu HC, Shih RD, Marcus S, Ruck B, Jennis T: Pseudomethemoglo- pramide therapy combined with N-acetylcysteine has binemia. Arch Pediatr Adolesc Med 1998; 152:803–5 also caused sulfhemoglobinemia.7,8 Our patient had 8. Langford SL, Sheikh S: An adolescent case of sulfhemoglobinemia been prescribed 30 mg/day metoclopramide for more associated with high-dose metoclopramide and N-acetylcysteine. Ann Emerg Med 1999; 34:538–41 than 1 yr. She was not administered any other drugs 9. Wu C, Kenny M: A case of sulfhemoglobinemia and emergency known to cause sulfhemoglobinemia. Metoclopramide