title: Pressure recording analytical method for measuring cardiac output in critically ill children: a validation study.
abstract: BACKGROUND
  Pressure recording analytical method (PRAM) is a novel, arterial pulse contour-based method for measuring cardiac output (CO). Validation studies of PRAM in children are few, and have not assessed both absolute accuracy and ability to track changes in CO across a broad case mix. We aimed to compare CO as measured by PRAM with that using a transpulmonary dilution method in a cohort of critically ill children.
  
  
  METHODS
  Forty-eight, mechanically ventilated children with a median (inter-quartile) weight of 10.7 (5.5-15) kg with arterial and central venous catheters in situ were studied. CO was measured simultaneously using PRAM and the comparator method, transpulmonary ultrasound dilution (UD). Measurements were repeated before and after therapeutic interventions that were intended to augment CO (e.g. fluid bolus).
  
  
  RESULTS
  In total, 210 paired measurements were compared. The mean (sd) CO was 1.9 (1.2) litre min(-1) with UD when compared with 1.92 (0.5) litre min(-1) using PRAM. The mean bias was 0.02 litre min(-1) with wide limits of agreement: ± 2.21 litre min(-1), giving a percentage error of 116%. The concordance between PRAM and UD for measuring changes in CO was also poor, with only 37% of measurements falling within the pre-defined polar plot limits of ±30°.
  
  
  CONCLUSIONS
  There is an unacceptably poor agreement between UD and PRAM. We do not recommend the use of PRAM for measuring CO in critically ill children with the current algorithm.
authors.affiliation: Paediatric Intensive Care Unit, Evelina Children's Hospital, Guy's and St Thomas' NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK.
authors.forename: R
authors.initials: R
authors.lastname: Saxena
authors.forename: A
authors.initials: A
authors.lastname: Durward
authors.forename: N K
authors.initials: NK
authors.lastname: Puppala
authors.forename: I A
authors.initials: IA
authors.lastname: Murdoch
authors.forename: S M
authors.initials: SM
authors.lastname: Tibby
mesh_terms: D000465:Algorithms; D062186:Arterial Pressure / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D002405:Catheterization, Central Venous; D002675:Child, Preschool; D015331:Cohort Studies; D003422:Critical Care; D016638:Critical Illness / Q000628:therapy*; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D007223:Infant; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D012015:Reference Standards; D012121:Respiration, Artificial