Non-invasive measurement of pulse pressure variation using a finger-cuff method in obese patients having laparoscopic bariatric surgery.

Pulse pressure variation (PPV) is a dynamic cardiac preload variable used to predict fluid responsiveness. PPV can be measured non-invasively using innovative finger-cuff systems allowing for continuous arterial pressure waveform recording, e.g., the Nexfin system [BMEYE B.V., Amsterdam, The Netherlands; now Clearsight (Edwards Lifesciences, Irvine, CA, USA)] (PPV). However, the agreement between PPV and PPV derived from an arterial catheter (PPV) in obese patients having laparoscopic bariatric surgery is unknown. We compared PPV and PPV at 6 time points in 60 obese patients having laparoscopic bariatric surgery in a secondary analysis of a prospective method comparison study. We used Bland-Altman analysis to assess absolute agreement between PPV and PPV. The predictive agreement for fluid responsiveness between PPV and PPV was evaluated across three PPV categories (PPV < 9%, PPV 9-13%, PPV > 13%) as concordance rate of paired measurements and Cohen's kappa. The overall mean of the differences between PPV and PPV was 0.5 ± 4.6% (95%-LoA - 8.6 to 9.6%) and the overall predictive agreement was 72.4% with a Cohen's kappa of 0.53. The mean of the differences was - 0.7 ± 3.8% (95%-LoA - 8.1 to 6.7%) without pneumoperitoneum in horizontal position and 1.1 ± 4.8% (95%-LoA - 8.4 to 10.5%) during pneumoperitoneum in reverse-Trendelenburg position. The absolute agreement and predictive agreement between PPV and PPV are moderate in obese patients having laparoscopic bariatric surgery.