title: Gender differences in cerebrovascular reactivity to carbon dioxide during sevoflurane anesthesia in children: preliminary findings.
abstract: BACKGROUND
  Cerebrovascular reactivity to carbon dioxide (CO(2) R) is affected by age, gender and anesthetic agents. While gender differences in CO(2) R are described in adults, there are no such data in children.
  
  
  OBJECTIVE
  To examine the gender differences in CO(2) R in children during sevoflurane anesthesia.
  
  
  METHODS
  Five girls and five boys <15 years of age and ASA physical status I, undergoing general anesthesia for elective surgery were enrolled. Under steady-state anesthesia with <1.0 MAC sevoflurane, middle cerebral artery blood flow velocity changes were monitored using Transcranial Doppler ultrasound while endtidal carbon dioxide (EtCO(2)) was adjusted from 40 to 30 mmHg (hypocapnia) and then from 40 to 50 mmHg (hypercapnia). CO(2)R was calculated between EtCO(2) ranges 30-40 and 40-50 mmHg. Cerebrovascular resistance (eCVR) was estimated as MAP/Vmca and the change in eCVR (ΔeCVR) between EtCO(2) 30 and 40 mmHg and between EtCO(2) 40 and 50 mmHg was calculated.
  
  
  RESULTS
  There was no gender difference in CO(2)R. However, both CO(2)R and ΔeCVR were lower in the EtCO(2) 40-50 mmHg range compared to EtCO(2) 30-40 mmHg range only in girls (P = 0.01 and P = 0.01, respectively). Vmca increased significantly with increase in CO(2) (P < 0.001) for both boys and girls. The coefficient of nonlinear correlation (r) between Vmca and EtCO(2) was 0.88 in girls vs 0.66 in boys.
  
  
  CONCLUSIONS
  While there were no gender differences in CO(2)R within the individual EtCO(2) ranges examined, girls but not boys had a significantly lower CO(2)R and ΔeCVR in the higher EtCO(2) range during <1.0 MAC sevoflurane anesthesia.
authors.affiliation: Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Arunotai
authors.initials: A
authors.lastname: Siriussawakul
authors.forename: Deepak
authors.initials: D
authors.lastname: Sharma
authors.forename: Pimwan
authors.initials: P
authors.lastname: Sookplung
authors.forename: William
authors.initials: W
authors.lastname: Armstead
authors.forename: Monica S
authors.initials: MS
authors.lastname: Vavilala
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D002245:Carbon Dioxide / Q000097:blood / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008738:Methyl Ethers; D020768:Middle Cerebral Artery / Q000502:physiology; D000077149:Sevoflurane; D012727:Sex Characteristics; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D002245:Carbon Dioxide; D000077149:Sevoflurane