title: The relation between hyperventilation and pediatric syncope.
abstract: OBJECTIVE
  The objective was to evaluate prospectively the role of hyperventilation in the development of neurocardiogenic syncope in children during head-upright tilt testing (HUTT).
  
  
  METHODS
  Tilt testing was performed in 34 children (mean age 10.6 years) with clinical suspicion of syncope. Respiratory rate and end-tidal carbon dioxide pressure were continuously monitored during HUTT.
  
  
  RESULTS
  Tilt test was negative in 12 cases; 3 (25%) patients of this group exhibited hyperventilation any time during the test. In the remaining 22 cases the HUTT was positive, and 15 (68.2%) patients of this group exhibited hyperventilation at the onset of clinical symptoms and during syncope. In the positive HUTT group, the mean time elapsed from the tilt to the onset of syncope and the mean time elapsed from the onset of clinical symptoms to syncope (latency time) were significantly longer for patients who hyperventilated than for those who did not hyperventilate, (21.8 vs 11.5 minutes) (P =.002) and (78 vs 51 seconds) (P =.04), respectively.
  
  
  CONCLUSIONS
  Spontaneous hyperventilation could play a relevant role in the pathophysiology of pediatric neurocardiogenic syncope, and it could point out a specific subtype of response to orthostatic stress in susceptible patients. We suggest the inclusion of capnography in tilt-test protocols could improve the assessment of syncope in children.
authors.affiliation: Pediatric Critical and Emergency Care Division, Department of Pediatrics, Complejo Hospitalario Universitario de Santiago de Compostela, c/A Choupana s/n, 15706 Santiago de Compostela, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Martinón-Torres
authors.forename: A
authors.initials: A
authors.lastname: Rodríguez-Núñez
authors.forename: S
authors.initials: S
authors.lastname: Fernández-Cebrián
authors.forename: J
authors.initials: J
authors.lastname: Eirís-Puñal
authors.forename: A
authors.initials: A
authors.lastname: Perez-Muñuzuri
authors.forename: J M
authors.initials: JM
authors.lastname: Martinón-Sánchez
mesh_terms: D000293:Adolescent; D002245:Carbon Dioxide / Q000032:analysis; D002648:Child; D006801:Humans; D006985:Hyperventilation / Q000150:complications*; D011187:Posture; D011446:Prospective Studies; D019462:Syncope, Vasovagal / Q000209:etiology*
chemical_list: D002245:Carbon Dioxide