title: Effect of Inhalational Anesthetics and Positive-pressure Ventilation on Ultrasound Assessment of the Great Vessels: A Prospective Study at a Children's Hospital.
abstract: BACKGROUND
  Bedside ultrasound has emerged as a rapid, noninvasive tool for assessment and monitoring of fluid status in children. The inferior vena cava (IVC) varies in size with changes in blood volume and intrathoracic pressure, but the magnitude of change to the IVC with inhalational anesthetic and positive-pressure ventilation (PPV) is unknown.
  
  
  METHODS
  Prospective observational study of 24 healthy children aged 1 to 12 yr scheduled for elective surgery. Ultrasound images of the IVC and aorta were recorded at five time points: awake; spontaneous ventilation with sevoflurane by mask; intubated with peak inspiratory pressure/positive end-expiratory pressure of 15/0, 20/5, and 25/10 cm H2O. A blinded investigator measured IVC/aorta ratios (IVC/Ao) and changes in IVC diameter due to respiratory variation (IVC-RV) from the recorded videos.
  
  
  RESULTS
  Inhalational anesthetic decreased IVC/Ao (1.1 ± 0.3 vs. 0.6 ± 0.2; P < 0.001) but did not change IVC-RV (median, 43%; interquartile range [IQR], 36 to 58% vs. 46%; IQR, 36 to 66%; P > 0.99). The initiation of PPV increased IVC/Ao (0.64 ± 0.21 vs. 1.16 ± 0.27; P < 0.001) and decreased IVC-RV (median, 46%; IQR, 36 to 66% vs. 9%; IQR, 4 to 14%; P < 0.001). There was no change in either IVC/Ao or IVC-RV with subsequent incremental increases in peak inspiratory pressure/positive end-expiratory pressure (P > 0.99 for both).
  
  
  CONCLUSIONS
  Addition of inhalational anesthetic affects IVC/Ao but not IVC-RV, and significant changes in IVC/Ao and IVC-RV occur with initiation of PPV in healthy children. Clinicians should be aware of these expected vascular changes when managing patients. Establishing these IVC parameters will enable future studies to better evaluate these measurements as tools for diagnosing hypovolemia or predicting fluid responsiveness.
authors.affiliation: From the Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania (E.E.L., T.C., J.K., A.N.); Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania (E.E.L., A.E.C., N.P., T.C., D.C., A.N.); Department of Emergency Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania (A.E.C.); and Department of Emergency Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania (N.P., N.R.J.).
authors.forename: Elaina E
authors.initials: EE
authors.lastname: Lin
authors.forename: Aaron E
authors.initials: AE
authors.lastname: Chen
authors.forename: Nova
authors.initials: N
authors.lastname: Panebianco
authors.forename: Thomas
authors.initials: T
authors.lastname: Conlon
authors.forename: Na Rae
authors.initials: NR
authors.lastname: Ju
authors.forename: Dustin
authors.initials: D
authors.lastname: Carlson
authors.forename: Jason
authors.initials: J
authors.lastname: Kopenitz
authors.forename: Akira
authors.initials: A
authors.lastname: Nishisaki
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001011:Aorta / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006776:Hospitals, Pediatric / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D008297:Male; D019095:Point-of-Care Systems / Q000706:statistics & numerical data; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D014463:Ultrasonography; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging*
chemical_list: D018685:Anesthetics, Inhalation