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A453
October 13, 2007 3:30 PM - 5:00 PM Room Room 301 |
| Ability of a Novel Algorithm for Fluid Responsiveness Monitoring in the Operating Room |
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Bertrand Delannoy, M.D., Olivier Desebbe, M.D., Olivier Bastien, M.D., Ph.D., Jean-Jacques Lehot, M.D., Ph.D., Maxime Cannesson, M.D. Anesthesiology, Hospices Civils de Lyon, Hôpital Louis Pradel, Lyon, France |
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Background: Respiratory variations in arterial pulse pressure (ΔPPman) are accurate predictors of fluid responsiveness in mechanically ventilated patients (Michard et al. Am J Respir Crit Care Med 2000;162:134-8). However, they can not be continuously monitored. The aim of our study was to assess the clinical utility of a novel algorithm based on automtaic detection algorithm, kernel smoothing, and rank-order filters (Aboy et al. IEEE Trans Biomed Eng 2004;51:2198-203) for automatic estimation of ΔPP (ΔPPauto). Methods: We studied 25 patients referred for coronary artery bypass grafting. ΔPPauto was continuously displayed using a method based on automatic detection algorithms, kernel smoothing, and rank-order filters (Intellivue MP70, Philips, Suresnes, France). This method only requires a standard, non specific, intra arterial catheter. All patients were under general anesthesia, mechanical ventilation, and were equipped with a pulmonary artery catheter. Central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), ΔPPman and ΔPPauto were recorded simultaneously at eight steps during surgery including before and after a volume expansion (VE) (500 ml hetastarch). ΔPPman was calculated as previously described : ΔPPman = (PPmax - PPmin)/[(PPmax + PPmin)/2] (Michard et al. Am J Respir Crit Care Med 2000;162:134-8). Responders to VE were defined as patients presenting > 15 % increase in cardiac index following VE. Receiver operating characteristic (ROC) curves were used to determine the ability of CVP, PCWP, ΔPPman and ΔPPauto to discriminate between responders and non responders to volume expansion. A p value < 0.05 was considered as statistically significant. Results: There was a strong and significant relationship (r=0.86; p < 0.01) and a good agreement (bias = 0.7 ± 3.4 %) between ΔPPman and ΔPPauto over the 200 pairs of collected data. Seventeen patients were responders to VE. A threshold ΔPPman value of 12 % allowed discrimination of responders to VE with a sensitivity of 88 % and a specificity of 100 %. A threshold ΔPPauto value of 10 % allowed discrimination of responders to VE with a sensitivity of 82 % and a specificity of 88 %. The areas under the ROC curves (± SE) were as follow: 0.923 ± 0.060 for ΔPPman, 0.919 ± 0.058 for ΔPPauto, 0.750 ± 0.106 for CVP, 0.651 ± 0.135 for PCWP (Figure). The area for ΔPPauto was significantly higher than the area for CVP and PCWP(p < 0.05 for both). Difference in area under the curve between ΔPPauto and ΔPPman did not reach significance (p = 0.86). Conclusion: ΔPPauto is strongly correlated to ΔPPman, is an accurate predictor of fluid responsiveness, and allows continuous monitoring of ΔPP. This novel algorithm has potential clinical applications.[figure1] Anesthesiology 2007; 107: A453 |
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