title: Continuous minimally invasive cardiac output monitoring with the COstatus in a neonatal swine model: recalibration is necessary during vasoconstriction and vasodilation.
abstract: BACKGROUND
  The COstatus monitor measures cardiac output via the transpulmonary ultrasound dilution method (COTPUD ) after injection of normal saline, and can calculate continuous cardiac output (CCO) from the arterial pressure waveform. The relationship between arterial waveform and COTPUD however, might be degraded during vasoconstriction/vasodilation.
  
  
  OBJECTIVE
  To examine if recalibration of arterial waveform-derived CCO is required during mild vasoconstriction/vasodilation.
  
  
  METHODS
  In 10 anesthetized piglets (6.6-10.1 kg), two COstatus monitors calculated the CCO from the same femoral arterial waveform before and during infusions of phenylephrine (PE; 1 or 3 mg·kg(-1) ·min(-1) ) and sodium nitroprusside (SNP; 1 or 5 mg·kg(-1) ·min(-1) ), administered in random order. One monitor was recalibrated (CCORecal ) after each intervention, while the other monitor was not (CCONon-Recal ). Recalibration was performed with COTPUD with 1 ml·kg(-1) normal saline as indicator. The effects of each infusion on hemodynamic parameters were compared with baseline using paired t-tests. The bias, limits of agreement (LOA), and percentage error between simultaneous measurements (CCORecal and CCONon-Recal ) were examined with Bland-Altman plots.
  
  
  RESULTS
  Infusion of PE significantly increased COTPUD , heart rate (HR), and arterial pressures but not systemic vascular resistance (SVR). Infusion of SNP decreased arterial pressures without affecting COTPUD , HR, and SVR. There was no bias between CCORecal and CCONon-Recal at the baseline, but a small bias was observed during PE and SNP infusions. The LOA increased approximately 10 fold during vasoconstriction and vasodilation. The percentage error increased from ≤ 5% to 32% and 27% during PE and SNP infusions, respectively.
  
  
  CONCLUSIONS
  Continuous cardiac output (CO) measured with the COstatus monitor requires recalibration during vasoconstriction and vasodilation, even if changes in COTPUD or SVR are not substantial.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
authors.forename: Alvaro F
authors.initials: AF
authors.lastname: Cisternas
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Martin-Flores
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
authors.forename: Robin D
authors.initials: RD
authors.lastname: Gleed
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002138:Calibration; D002302:Cardiac Output / Q000502:physiology*; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging*; D007201:Indicator Dilution Techniques; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D015203:Reproducibility of Results; D012965:Sodium Chloride / Q000008:administration & dosage; D013552:Swine; D014463:Ultrasonography; D014661:Vasoconstriction / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*
chemical_list: D012965:Sodium Chloride
keywords: anesthesia; hemodynamics; pediatric