Is applanation tonometry a reliable method for monitoring blood pressure in morbidly obese patients undergoing bariatric surgery?
BACKGROUND
The aim of this study was to evaluate the validity of non-invasive continuous BP measurement by applanation tonometry in morbidly obese patients undergoing bariatric surgery.


METHODS
Arterial blood pressure (AP) was recorded intraoperatively both by applanation tonometry (AT) (T-Line 200pro, Tensys Medical(®), USA) and an arterial line (AL) after radial cannulation in obese patients undergoing bariatric surgery. Discrepancies between the two methods were assessed as bias, limits of agreement and percentage error. Mean, systolic, and diastolic arterial pressures were assessed (MAP, SAP, DAP respectively). Trending ability was assessed by concordance based on four-quadrant plotting.


RESULTS
Mean (sd) BMI of the 28 patients was 49.4 (9.7 kg m(-2)). A total of 201 907 time points were available for analysis. Bias for MAPAT compared with MAPAL was +3.97 mm Hg (SAPAT +3.45 mm Hg; DAPAT +3.66 mm Hg) with limits of agreement for MAPAT of -14.47 and +22.41 mm Hg (SAPAT -22.0 and +28.9 mm Hg; DAPAT -15.7 and +23.1 mm Hg). Percentage error for MAPAT was 23.5% (23.4% for SAPAT; 30.5% for DAPAT). Trending ability for MAP, SAP, and DAP revealed a concordance of 0.74, 0.72, and 0.71, respectively.


CONCLUSIONS
Continuous BP assessment by applanation tonometry is feasible in morbidly obese patients undergoing bariatric surgery. However, despite a low mean difference, 95% limits of agreement and trending ability indicate that the technology needs to be improved further, before being recommended for routine use in this group of patients.
Department of Anaesthesiology g.greiwe@uke.de.
G
G
Greiwe
Department of Intensive Care Medicine, University Medical Centre Hamburg-Eppendorf, Centre of Anaesthesiology and Intensive Care Medicine, Martinistrasse 52, 20246 Hamburg, Germany.
P A
PA
Tariparast
Department of Anaesthesiology.
C
C
Behem
Department of Anaesthesiology.
M
M
Petzoldt
University of Cologne, Institute of Medical Statistics, Informatics and Epidemiology, Kerpener Str.62, 50937 Köln, Germany.
L
L
Herich
Department of Anaesthesiology.
C J
CJ
Trepte
Department of Anaesthesiology.
D A
DA
Reuter
Department of Anaesthesiology.
S A
SA
Haas
D000328:Adult; D000368:Aged; D062186:Arterial Pressure; D050110:Bariatric Surgery / Q000379:methods*; D001795:Blood Pressure Determination / Q000379:methods*; D015992:Body Mass Index; D003422:Critical Care; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery*; D011446:Prospective Studies; D015203:Reproducibility of Results; D055815:Young Adult
arterial pressure; bariatric surgery; blood pressure monitors; monitoring, intraoperative