title: Are nocturnal hypoxemia and hypercapnia associated with desaturation immediately after adenotonsillectomy?
abstract: BACKGROUND
  Children who undergo adenotonsillectomy for sleep-disordered breathing frequently have postoperative oxygen desaturations. Nocturnal hypoxia has been shown to predict postoperative respiratory complications; however, other gas exchange abnormalities detected on polysomnography (PSG) have not been evaluated.
  
  
  OBJECTIVE
  We sought to determine whether hypercapnia seen on preoperative nocturnal PSG can predict postoperative hypoxemia.
  
  
  METHODS
  We conducted a retrospective review of 319 children who underwent polysomnography before adenotonsillectomy. Saturation levels were recorded for at least 2 h postoperatively, and the primary outcome was desaturation (<90%).
  
  
  RESULTS
  The median patient age was 5 years (range, 5 months-17 years). Patients who desaturated postoperatively had higher median peak endtidal CO2 (EtCO2 ) levels (55.5 vs 52 mmHg; P = 0.02), lower saturation nadirs (80.5% vs 88%; P = 0.048), and were younger (2 vs 6 years; P < 0.001) than those without desaturation. Age was significantly correlated with peak EtCO2 (r = -0.16), respiratory disturbance index (RDI; r = -0.23), and oxygen saturation nadir (r = 0.25; all P < 0.01). In unadjusted analysis, age <3 years compared to ≥9 years (odds ratio [OR] = 10.09; 95% confidence interval [CI] = 2.13-96.26), peak EtCO2  > 55 mmHg (OR = 3.38; 95% CI = 1.21-9.47), and RDI ≥ 10 (OR = 2.89; 95% CI = 1.05-8.42) were associated with increased odds of desaturation. Multivariable logistic regression on age, race, sex, peak EtCO2 , RDI, opioid use, and saturation nadir showed that only age was significantly associated with postoperative desaturation. Patients 0-2 years old were 10.43 (95% CI = 1.89-110.9) times more likely to have desaturation than patients 9-17 years old.
  
  
  CONCLUSIONS
  Patients <3 years of age are most likely to have postoperative hypoxemia after adenotonsillectomy. Gas exchange abnormalities did not correlate with postoperative desaturations, although age and peak EtCO2 did strongly correlate.
authors.affiliation: Division of Pediatric Anesthesiology/Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.|Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Dalesio
authors.affiliation: Division of Pediatric Anesthesiology/Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Douglas H
authors.initials: DH
authors.lastname: McMichael
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Benke
authors.affiliation: Division of Pediatric Anesthesiology/Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Owens
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Carson
authors.affiliation: Division of Pediatric Anesthesiology/Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Schwengel
authors.affiliation: Department of Internal Medicine-Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Schwartz
authors.affiliation: Division of Otolaryngology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.|Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.|Department of Otolaryngology-Head & Neck Surgery, University of Cincinnati School of Medicine, Cincinnati, OH, USA.|Department of Pediatrics, University of Cincinnati School of Medicine, Cincinnati, OH, USA.
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Ishman
mesh_terms: D000233:Adenoidectomy; D000293:Adolescent; D000367:Age Factors; D001784:Blood Gas Analysis / Q000706:statistics & numerical data; D002245:Carbon Dioxide / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000453:epidemiology*; D000860:Hypoxia / Q000453:epidemiology*; D007223:Infant; D008297:Male; D010100:Oxygen / Q000378:metabolism; D017286:Polysomnography / Q000706:statistics & numerical data; D011183:Postoperative Complications / Q000453:epidemiology*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000706:statistics & numerical data*; D014068:Tonsillectomy
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: desaturation; hypercapnia; polysomnography; postoperative complications; sleep apnea, obstructive; tonsillectomy