The accuracy of Pleth Variability Index for directed fluid optimization in donors in living donor liver transplantation

Background Fluid management strongly affects hepatic resection and aims to reduce intraoperative bleeding during living donation. The Pleth Variability Index (PVI) is a tool to assess the fluid responsiveness from the pulse oximeter waveform; we evaluated the efficacy and accuracy of finger PVI compared to pulse pressure variation (PPV) from arterial waveform in predicting the fluid response in donor hepatectomy patients with the guide of non-invasive cardiac output (CO) measurements. We recruited forty patients who were candidates for right lobe hepatectomy for liver transplantation under conventional general anesthesia methods. During periods of intraoperative hypovolemia not affected by surgical manipulation, PVI, PPV, and CO were recorded then compared with definitive values after fluid bolus administration of 3–5 ml/kg aiming to give a 10% increase in CO which classified the patients into responders and non-responders. Results Both PPV and PVI showed a significant drop after fluid bolus dose (P < 0.001) leading to an increase of the CO (P < 0.0001), and the area under the curve was 0.934, 0.842 (95% confidence interval, 0.809 to 0.988, 0.692 to 0.938) and the standard error was 0.0336, 0.124, respectively. Pairwise comparison of PPV and PVI showed non-significant predictive value between the two variables (P = 0.4605); the difference between the two areas was 0.0921 (SE 0125 and 95% CI − 0.152 to 0.337). Conclusions PVI is an unreliable indicator for fluid response in low-risk donors undergoing right lobe hepatectomy compared to PPV. We need further studies with unbiased PVI monitors in order to implement a non-invasive and safe method for fluid responsiveness.

The use of oxygen reserve index in one-lung ventilation and its impact on peripheral oxygen saturation, perfusion index and, pleth variability index

Background Our goal is to investigate the use of the oxygen reserve index (ORi) to detect hypoxemia and its relation with parameters such as; peripheral oxygen saturation, perfusion index (PI), and pleth variability index (PVI) during one-lung ventilation (OLV). Methods Fifty patients undergoing general anesthesia and OLV for elective thoracic surgeries were enrolled in an observational cohort study in a tertiary care teaching hospital. All patients required OLV after a left-sided double-lumen tube insertion during intubation. The definition of hypoxemia during OLV is a peripheral oxygen saturation (SpO2) value of less than 95%, while the inspired oxygen fraction (FiO2) is higher than 50% on a pulse oximetry device. ORi, pulse oximetry, PI, and PVI values were measured continuously. Sensitivity, specificity, positive and negative predictive values, likelihood ratios, and accuracy were calculated for ORi values equal to zero in different time points during surgery to predict hypoxemia. At Clinicaltrials.gov registry, the Registration ID is NCT05050552. Results Hypoxemia was observed in 19 patients (38%). The accuracy for predicting hypoxemia during anesthesia induction at ORi value equals zero at 5 min after intubation in the supine position (DS5) showed a sensitivity of 92.3% (95% CI 84.9–99.6), specificity of 81.1% (95% CI 70.2–91.9), and an accuracy of 84.0% (95% CI 73.8–94.2). For predicting hypoxemia, ORi equals zero show good sensitivity, specificity, and statistical accuracy values for time points of DS5 until OLV30 where the sensitivity of 43.8%, specificity of 64%, and an accuracy of 56.1% were recorded. ORi and SpO2 correlation was found at DS5, 5 min after lateral position with two-lung ventilation (DL5) and at 10 min after OLV (OLV10) (p = 0.044, p = 0.039, p = 0.011, respectively). Time-dependent correlations also showed that; at a time point of DS5, ORi has a significant negative correlation with PI whereas, no correlations with PVI were noted. Conclusions During the use of OLV for thoracic surgeries, from 5 min after intubation (DS5) up to 30 min after the start of OLV, ORi provides valuable information in predicting hypoxemia defined as SpO2 less than 95% on pulse oximeter at FiO2 higher than 50%.

The Use of Oxygen Reserve Index in One-Lung Ventilation and Its Impact On Peripheral Oxygen Saturation, Perfusion Index and Pleth Variability Index

Background: Our goal is to investigate the use of the Oxygen Reserve Index (ORi) and its relation with peripheral oxygen saturation, perfusion index (PI), and pleth variability index (PVI) during one-lung ventilation (OLV).Methods: Fifty patients undergoing general anesthesia and OLV for elective thoracic surgeries were enrolled in an observational cohort study in a tertiary care teaching hospital. During general anesthesia induction, propofol, fentanyl, and rocuronium at appropriate doses were administered intravenously. All patients required OLV after a left-sided double-lumen tube insertion during intubation. Hypoxemia during OLV was defined as peripheral oxygen saturation (SpO2) value of less than 95% when the inspired oxygen fraction (FiO2) is above 60% on a pulse oximetry device. ORi, pulse oximetry, PI, and PVI were measured continuously. Sensitivity, specificity, positive and negative predictive values, likelihood ratios, and accuracy were calculated for ORi equals zero in different anesthesia time points to predict hypoxemia. At Clinicaltrials.gov registry, the Registration ID is NCT05050552.Results: The accuracy for predicting hypoxemia during anesthesia induction at ORi value equals zero at five minutes after intubation in the supine position (DS5) showed a sensitivity of 92.3% (95% CI 84.9-99.6), specificity of 81.1% (95% CI 70.2-91.9), and an accuracy of 84.0% (95% CI 73.8- 94.2). ORi and SpO2 correlation was found at DS5 (p = 0.044), 5 minutes after lateral position with two-lung ventilation (DL5) (p = 0.039), and at 10 minutes after OLV (OLV10)(p = 0.011).Conclusions: ORi equals zero at the time point of five minutes after tracheal intubation in the supine position (DS5) showed high sensitivity and specificity for predicting hypoxemia at a less than 95% value.

Pleth variability index and fluid management practices: a multicenter service evaluation

Objectives The introduction of a new technology has the potential to modify clinical practices, especially if easy to use, reliable and non-invasive. This observational before/after multicenter service evaluation compares fluid management practices during surgery (with fluids volumes as primary outcome), and clinical outcomes (secondary outcomes) before and after the introduction of the Pleth Variability Index (PVI), a non-invasive fluid responsiveness monitoring. Results In five centers, 23 anesthesiologists participated during a 2-years period. Eighty-eight procedures were included. Median fluid volumes infused during surgery were similar before and after PVI introduction (respectively, 1000 ml [interquartile range 25–75 [750–1700] and 1000 ml [750–2000]). The follow-up was complete for 60 from these and outcomes were similar. No detectable change in the fluid management was observed after the introduction of a new technology in low to moderate risk surgery. These results suggest that the introduction of a new technology should be associated with an implementation strategy if it is intended to be associated with changes in clinical practice.

Pleth variability index may predict preload responsiveness in patients treated with nasal high flow: a physiological study

The purpose of this study was to determine whether the plethysmographic variability index (PVi) can predict preload responsiveness in nasal high flow (NHF) patients (≥30 L/min) with any sign of hypoperfusion. Preload responsiveness was defined as a ≥10% increase in stroke volume (SV), measured by transthoracic echocardiography, after passive leg raising. SV and PVi were reassessed in preload responders after receiving a 250-mL fluid challenge. Twenty patients were included, and 12 patients (60%) were preload responders. Responders showed higher baseline mean PVi (24% vs. 13%; p=0.001) and higher mean PVi variation (∆PVi) after passive leg raising (6.8% vs. -1.7%; p<0.001). No differences between mean ∆PVi after passive leg raising and mean ∆PVi after fluid challenge were observed (6.8 % vs. 7.4%; p=0.24), and both values were strongly correlated (r=0.84; p<0.001). Baseline PVi and ∆PVi after passive leg raising showed excellent diagnostic accuracy identifying preload responders (AUROC 0.92 and 1.00, respectively). Baseline PVi ≥16% had a sensitivity of 91.7% and a specificity of 87.5% for detecting preload responders. Similarly, ∆PVi after passive leg raising ≥2%, had a 100% of both sensitivity and specificity. Thus, PVi might predict preload responsiveness in patients treated with NHF, suggesting that it may guide fluid administration in these patients.