title: Echocardiographic estimation of mean pulmonary artery pressure in critically ill patients.
abstract: BACKGROUND
  Indirect assessment of mean pulmonary arterial pressure (MPAP) may assist management of critically ill patients with pulmonary hypertension and right heart dysfunction. MPAP can be estimated as the sum of echocardiographically derived mean right ventricular to right atrial systolic pressure gradient and right atrial pressure; however, this has not been validated in critically ill patients.
  
  
  METHODS
  This prospective validation study was conducted in patients undergoing pulmonary artery catheterisation during intensive care admission. Pulmonary artery catheter (PAC) measurements of MPAP were contemporaneously compared to MPAP estimated utilising transthoracic echocardiography (TTE)-derived mean right ventricular to right atrial systolic pressure gradient added to invasively measured right atrial pressure.
  
  
  RESULTS
  Of 53 patients assessed, 23 had estimable MPAP using TTE. The mean difference between TTE- and PAC-derived MPAP was 1.9 mmHg (SD 5.0), with upper and lower limits of agreement of 11.6 and -7.9 mmHg, respectively. The median absolute percentage difference between TTE- and PAC-derived MPAP was 7.5%. Inter-rater reliability assessment was performed for 15 patients, giving an intra-class correlation coefficient of 0.96 (95% confidence intervals, 0.89 to 0.99).
  
  
  CONCLUSIONS
  This echocardiographic method of estimating MPAP in critically ill patients was not equivalent to invasively measured MPAP, based on our predefined clinically acceptable range (±5 mmHg). The accuracy of this method in critically ill patients was similar to the results obtained in ambulatory patients and compared favourably with regard to the accuracy with echocardiographic estimation of systolic pulmonary arterial pressure. The utility of this technique is limited by frequent inability to obtain an adequate tricuspid regurgitant time-velocity integral in critically ill patients.
authors.affiliation: Intensive and Critical Care Unit, Flinders Medical Centre, Flinders Drive, Bedford Park, SA 5042, Australia.
authors.forename: Russell D
authors.initials: RD
authors.lastname: Laver
authors.affiliation: Intensive and Critical Care Unit, Flinders Medical Centre, Flinders Drive, Bedford Park, SA 5042, Australia.
authors.forename: Ubbo F
authors.initials: UF
authors.lastname: Wiersema
authors.affiliation: Intensive and Critical Care Unit, Flinders Medical Centre, Flinders Drive, Bedford Park, SA 5042, Australia ; School of Medicine, Flinders University, Sturt Road, Bedford Park, SA 5042, Australia.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bersten
keywords: Critical care; Echocardiography; Hypertension; Intensive care; Pulmonary