Automatic algorithm for monitoring systolic pressure variation and difference in pulse pressure.
BACKGROUND
Difference in pulse pressure (dPP) reliably predicts fluid responsiveness in patients. We have developed a respiratory variation (RV) monitoring device (RV monitor), which continuously records both airway pressure and arterial blood pressure (ABP). We compared the RV monitor measurements with manual dPP measurements.


METHODS
ABP and airway pressure (PAW) from 24 patients were recorded. Data were fed to the RV monitor to calculate dPP and systolic pressure variation in two different ways: (a) considering both ABP and PAW (RV algorithm) and (b) ABP only (RV(slim) algorithm). Additionally, ABP and PAW were recorded intraoperatively in 10-min intervals for later calculation of dPP by manual assessment. Interobserver variability was determined. Manual dPP assessments were used for comparison with automated measurements. To estimate the importance of the PAW signal, RV(slim) measurements were compared with RV measurements.


RESULTS
For the 24 patients, 174 measurements (6-10 per patient) were recorded. Six observers assessed dPP manually in the first 8 patients (10-min interval, 53 measurements); no interobserver variability occurred using a computer-assisted method. Bland-Altman analysis showed acceptable bias and limits of agreement of the 2 automated methods compared with the manual method (RV: -0.33% +/- 8.72% and RV(slim): -1.74% +/- 7.97%). The difference between RV measurements and RV(slim) measurements is small (bias -1.05%, limits of agreement 5.67%).


CONCLUSIONS
Measurements of the automated device are comparable with measurements obtained by human observers, who use a computer-assisted method. The importance of the PAW signal is questionable.
Pestel
Gunther
G
Department of Anesthesiology, Johannes Gutenberg-University, Mainz, Germany.
Fukui
Kimiko
K
Hartwich
Volker
V
Schumacher
Peter M
PM
Vogt
Andreas
A
Hiltebrand
Luzius B
LB
Kurz
Andrea
A
Fujita
Yoshihisa
Y
Inderbitzin
Daniel
D
Leibundgut
Daniel
D
D000005:Abdomen / Q000601:surgery; D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology; D000465:Algorithms; D001331:Automation; D001794:Blood Pressure / Q000502:physiology*; D001810:Blood Volume / Q000502:physiology; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D015588:Observer Variation; D011674:Pulse; D012015:Reference Standards; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology