title: Hypoxemia During Extreme Hyperleukocytosis: How Spurious?
abstract: BACKGROUND
  Spurious hypoxemia has been described in case reports during extreme hyperleukocytosis and has led to recommendations for immediate cooling and analysis of arterial blood gases (ABGs). We sought to determine, in samples processed as recommended, the magnitude of spurious hypoxemia in acute leukemia subjects with hyperleukocytosis.
  
  
  METHODS
  A retrospective chart review was conducted of all subjects admitted between 2003 and July 2014 for acute leukemia, who presented with white blood cell (WBC) count > 50 × 10(9) cells/L and had ABGs performed. For each ABG, we collected PaO2 , SaO2 , simultaneous WBC count, and SpO2 when available. Bland and Altman analysis was used to assess the agreement between SpO2 and SaO2 .
  
  
  RESULTS
  One-hundred forty-six samples (from 45 subjects) were included, of which 57 samples (from 18 subjects) had data available for Bland and Altman analysis. Mean (SpO2 - SaO2 ) was 2.5%, and 95% CI for limits of agreement between SpO2 and SaO2 was (-10.1,15.1)%. The mean (SpO2 - SaO2 ) was significantly higher for WBC count > 100 × 10(9)/L as compared with WBC count < 100 × 10(9)/L (3.8% vs 0.4%, P = .04), and the 95% CIs for limits of agreement were (-10.3,18)% versus (-7.9,8.6)%. SpO2 and SaO2 were poorly correlated (r(2) = 0.19), whereas the difference (SpO2 - SaO2 ) was fairly correlated with WBC count (r(2) = 0.44). Overall, 11 of 19 samples with WBC count > 150 × 10(9)/L had PaO2 < 55 mm Hg whereas SpO2 was > 94%, the proportion being 5 of 62 samples for WBC count < 150 × 10(9)/L (P < .001). Three subjects with WBC count > 150 × 10(9)/L exhibited large SpO2 to SaO2 differences (10-20%) before leukapheresis, which decreased to below 5% afterward.
  
  
  CONCLUSIONS
  In subjects with acute leukemia and hyperleukocytosis, despite cooling and quickly analyzing the samples, we observed poor correlation and agreement between SpO2 and SaO2 , unacceptably low for WBC count > 100 × 10(9)/L. Our results suggest that current guidelines may not totally prevent the diagnosis of spurious hypoxemia.
authors.affiliation: Division of Pulmonary and Critical Care Medicine avandelouw@hmc.psu.edu.
authors.forename: Andry
authors.initials: A
authors.lastname: Van de Louw
authors.affiliation: Department of Internal Medicine.
authors.forename: Ruchi J
authors.initials: RJ
authors.lastname: Desai
authors.affiliation: Department of Internal Medicine.
authors.forename: Coursen W
authors.initials: CW
authors.lastname: Schneider
authors.affiliation: Division of Hematology and Oncology, Penn State Milton S Hershey Medical Center and College of Medicine, Hershey, Pennsylvania.
authors.forename: David F
authors.initials: DF
authors.lastname: Claxton
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis / Q000379:methods; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D007937:Leukapheresis; D015470:Leukemia, Myeloid, Acute / Q000150:complications*; D015473:Leukemia, Promyelocytic, Acute / Q000150:complications; D007958:Leukocyte Count; D007964:Leukocytosis / Q000097:blood* / Q000209:etiology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D010100:Oxygen
keywords: acute leukemia; blood gas analysis; hypoxemia; leukocytosis; oximetry; oxygen