title: Impact of rapid leukodepletion on the outcome of severe clinical pertussis in young infants.
abstract: OBJECTIVE
  Bordetella pertussis is a common, underrecognized, and vaccine-preventable cause of critical illness with a high mortality in infants worldwide. Patients with severe cases present with extreme leukocytosis and develop refractory hypoxemia and pulmonary hypertension that is unresponsive to maximal intensive care. This may reflect a hyperviscosity syndrome from the raised white blood cell (WBC) count. Case reports suggest improved outcomes with exchange transfusion to reduce the WBC count. Our objective was to quantify possible benefits of aggressive leukodepletion.
  
  
  METHODS
  We, as a regional PICU and extracorporeal membrane oxygenation referral center, adopted a strategy of aggressive leukodepletion in January 2005. The impact of this strategy on crude and case mix-adjusted survival of all infants who were critically ill with B pertussis were compared with control subjects from January 2001 to December 2004 and Extracorporeal Life Support Organisation registry data.
  
  
  RESULTS
  Nineteen infants (7 [37%] boys) received intensive care for B pertussis from 2001 to 2009. Admission WBC counts were equivalent in 2 time periods: 2001-2004 (mean: 52,000/μL) and 2005-2009 (mean: 75,000/μL). In 2001-2004, 5 (55%) of 9 patients survived the ICU. Between 2005 and 2009, 9 (90%) of 10 patients survived. When case-mix adjustment for age, WBC count, and extracorporeal membrane oxygenation referral were considered, the 2001-2004 predicted survival (4.4 [49%] of 9.0) was equivalent to the observed mortality (4.0 [44%] of 9.0). Between 2005 and 2009, observed mortality (1.0 [10%] of 10.0) was significantly better than predicted (4.7 [47%] of 10.0).
  
  
  CONCLUSIONS
  Leukodepletion should be considered in critically ill infants with B pertussis and leukocytosis.
authors.affiliation: Cardiac Critical Care Unit, Great Ormond Street Hospital for Children NHS Trust, and Critical Care Group, Portex Unit, Institute of Child Health, University College London, London, UK.
authors.forename: Helen E
authors.initials: HE
authors.lastname: Rowlands
authors.forename: Allan P
authors.initials: AP
authors.lastname: Goldman
authors.forename: Karen
authors.initials: K
authors.lastname: Harrington
authors.forename: Ann
authors.initials: A
authors.lastname: Karimova
authors.forename: Joe
authors.initials: J
authors.lastname: Brierley
authors.forename: Nigel
authors.initials: N
authors.lastname: Cross
authors.forename: Sophie
authors.initials: S
authors.lastname: Skellett
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Peters
mesh_terms: D016638:Critical Illness; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D006801:Humans; D007223:Infant; D015278:Intensive Care Units, Pediatric; D047589:Leukocyte Reduction Procedures; D007964:Leukocytosis / Q000150:complications / Q000628:therapy; D008297:Male; D012307:Risk Factors; D014917:Whooping Cough / Q000097:blood / Q000401:mortality / Q000628:therapy*