Predictive value of the respiratory exchange ratio for the occurrence of postoperative complications in laparoscopic surgery: a prospective and observational study.

Indirect measurement of the respiratory exchange ratio (RER) has been shown to predict the occurrence of postoperative complications after major open non-cardiac surgery. Our main objective was to demonstrate the ability of the RER, indirectly measured by the anaesthesia respirator, to predict the occurrence of postoperative complications following laparoscopic surgery. We performed an observational, prospective and monocentric study. Haemodynamic and respiratory parameters were collected at several timepoints to calculate the RER by a non-volumetric method: RER = (FetCO2-FiCO2)/(FiO2-FetO2). Fifty patients were prospectively included. Nine patients (18%) had at least one postoperative complication. The mean RER was significantly higher for the subgroup of patients with complications than the subgroup without (1.04 ± 0.27 vs 0.88 ± 0.13, p < 0.05). The RER could predict the occurrence of post-operative complications with an area under the ROC curve of 0.73 (95% CI 0.59-0.85, p = 0.021). The best cut off was 0.98, with a sensitivity of 56% and a specificity of 88%. One hour after insufflation, the FiO2-FetO2 difference was significantly lower and the RER was significantly higher in the complications subgroup than in the subgroup without complications (4.4/- 1.6% vs 5.8/- 1.2%, p = 0.001 and 0.95 [0.85-1.04] vs 0.83 [0.75-0.92], p = 0.04, respectively). The RER measured during laparoscopic surgery can predict the occurrence of postoperative complications.Trial registration The objectives and procedures of the study was registered at Clinicaltrials.gov (NCT03751579); date: November 23, 2018.

Predicting postoperative complications with the respiratory exchange ratio after high-risk noncardiac surgery: A prospective cohort study.

BACKGROUND: The respiratory exchange ratio (RER), defined as the ratio of CO2 production (VCO2) to O2 consumption (VO2), is reported to be a noninvasive marker of anaerobic metabolism. The intubated, ventilated patient's inspired and expired fractions of O2 and CO2 (FiO2, FeO2, FiCO2 and FeCO2) are monitored in the operating room and can be used to calculate RER. OBJECTIVE: To investigating the ability of the RER to predict postoperative complications. DESIGN: An observational, prospective study. SETTING: Two French university hospitals between March 2017 and September 2018. PATIENTS: A total of 110 patients undergoing noncardiac high-risk surgery. MAIN OUTCOME MEASURES: The RER was calculated as (FeCO2 - FiCO2)/(FiO2 - FeO2) at five time points during the operation. The primary endpoint was at the end of the surgery. The secondary endpoints were systemic oxygenation indices (pCO2 gap, pCO2 gap/arteriovenous difference in O2 ratio, central venous oxygen saturation) and the arterial lactate level at the end of the surgery. Complications were classified according to the European Peri-operative Clinical Outcome definitions. RESULTS: Postoperative complications occurred in 35 patients (34%). The median [interquartile range] RER at the end of surgery was significantly greater in the subgroup with complications, 1.06 [0.84 to 1.35] than in the subgroup without complications, 0.81 [0.75 to 0.91], and correlated significantly with the arterial lactate (r = 0.31, P < 0.001) and VO2 (r = -0.23, P = 0.001). Analysis of the area under the receiver operating characteristic curve for the predictive value of RER for postoperative complications revealed a value of 0.77 [95% confidence interval (CI) 0.69 to 0.88, P = 0.001]. The best cut-off for the RER was 0.94, with a sensitivity of 71% (95% CI 54 to 85) and a specificity of 79% (95% CI 68 to 88). CONCLUSION: As a putative noninvasive marker of tissue hypoperfusion and anaerobic metabolism, the RER can be used to predict complications following high-risk surgery. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03471962.

Low-positive pressure ventilation improves non-hypoxaemic apnoea tolerance during ear, nose and throat pan-endoscopy: A randomised controlled trial.

BACKGROUND: It has been suggested that oxygenation using pressure support ventilation (PSV) before general anaesthesia can reduce the duration of non-hypoxaemic apnoea. OBJECTIVE: The objective was to determine whether or not pre-oxygenation with PSV increases the duration of non-hypoxaemic apnoea in non-obese patients during pan-endoscopy. DESIGN: A randomised, controlled trial. SETTING: Amiens University Hospital, France. PATIENTS: Fifty patients scheduled for ENT pan-endoscopy with a BMI lower than 35  kg  m(-2). INTERVENTION: Patients scheduled for pan-endoscopy were enrolled to receive either 100% oxygen at neutral pressure (the control group) or 100% oxygen with positive-pressure ventilation (a positive inspiratory pressure of 4  cmH2O and a positive end-expiratory pressure of 4  cmH2O; the PSV group) during spontaneous ventilation with a face mask. The goal of pre-oxygenation was to obtain an end-tidal oxygen concentration of more than 90% prior to induction of anaesthesia. MAIN OUTCOME MEASURES: The primary efficacy criterion was the duration of non-hypoxaemic apnoea (i.e. before the peripheral capillary oxygen saturation fell to 90%). Secondary outcomes were duration of pre-oxygenation, pre-oxygenation failure and tolerance. RESULTS: The mean (interquartile range) duration of non-hypoxaemic apnoea was longer in the PSV group [598 (447 to 717) s] than in the control group [310 (217 to 451) s] (P < 0.001). Oxygenation time was shorter in the PSV group [190 (159 to 225) s] than in the control group [245 (151 to 435) s] (P = 0.037). Pre-oxygenation was unsuccessful (i.e. end-tidal oxygen concentration was < 90%) in 20% of the patients in the control group but none in the PSV group. The intergroup difference in the duration of pan-endoscopy was not significant. Tolerance was good or very good in all patients. CONCLUSION: Our results show that pre-oxygenation with PSV is associated with a longer duration of non-hypoxaemic apnoea and a lower frequency of manual reventilation during ENT pan-endoscopy. CLINICALTRIALS. GOV REGISTRATION NUMBER: NCT02167334.

Portal Vein Pulsatility Index as a Potential Risk of Venous Congestion Assessed by Magnetic Resonance Imaging: A Prospective Study on Healthy Volunteers.

High values of the portal vein pulsatility index (PI) have been associated with adverse outcomes in perioperative or critically ill patients. However, data on dynamic changes of PI related to fluid infusion are scarce. We aimed to determine if dynamic changes in PI are associated with the fluid challenge (FC). To address this challenge, we conducted a prospective single-center study. The population study included healthy subjects. FC consisted in the administration of 500 ml of Ringer lactate infusion over 5 min. The portal blood flow and PI were assessed by magnetic resonance imaging. The responsiveness to FC was defined as an increase in the cardiac stroke volume of at least 10% as assessed by echocardiography. We included 24 healthy volunteers. A total of fourteen (58%) subjects were responders, and 10 (42%) were non-responders. In the responder group, FC induced a significant increase in portal blood flow from 881 (762-1,001) at the baseline to 1,010 (778-1,106) ml min-1 (p = 0.005), whilst PI remained stable (from 31 [25-41] to 35 (25-42) %; p = 0.12). In the non-responder group, portal blood flow remained stable after FC (from 1,042 to 1,034 ml min-1; p = 0.084), whereas PI significantly increased from 32 (22-40) to 48% *(25-85) after FC (p = 0.027). PI was negatively correlated to portal blood flow (Rho coefficient = -0.611; p = 0.002). To conclude, PI might be a sensitive marker of early congestion in healthy subjects that did not respond to FC. This finding requires further validation in clinical settings with a larger sample size.

The predictability of dynamic preload indices depends on the volume of fluid challenge: A prospective observational study in the operating theater.

This study was designed to assess the association between volume of fluid challenge (FC) and predictability of respiratory variation of stroke volume (ΔrespSV) in the operating theater.Patients undergoing intermediate/high-risk surgery and monitored by esophageal Doppler monitoring (EDM) were prospectively included. All patients were under general anesthesia and mechanically ventilated. Exclusion criteria were frequent ectopic beats or preoperative arrhythmia, right ventricular failure, and spontaneous breathing. Hemodynamic parameters and esophageal Doppler indices (SV, cardiac output, ΔrespSV) were collected before, after infusion of 250 mL, and after infusion of 500 mL of crystalloid solution. Responders were defined by a >15% increase of stroke volume after FC at each step.After infusion of a 250 mL FC, 41 patients (32%) were classified as fluid responders (R250). After infusion of a 500 mL FC, 80 patients (63%) were classified as fluid responders (R500). The predictability of ΔrespSV was fair with an area under the curve (AUC) of 0.79 (95% CI 0.71-0.86, P < .001) to predict fluid responsiveness with a 250 mL FC. With an AUC of 0.94 (95% CI 0.88-0.97, P < .0001), ΔrespSV presented an excellent ability to predict fluid responsiveness with a 500-mL FC.Predictability of ΔrespSV changed with the volume of fluid infused to assess fluid responsiveness. The accuracy of ΔrespSV was higher with 500 mL than with 250 mL. Bedside studies evaluating the predictability of dynamic preload indices should define fluid responsiveness as a >15% increase of SV in response to a 500-mL FC.

Outcome of Transurethral Resection of Bladder Tumor: Does Antiplatelet Therapy Really Matter? Analysis of a Retrospective Series.

INTRODUCTION: Transurethral resection of bladder tumor (TURBT) is considered to be at a moderate or high risk of bleeding during surgical procedure. The number of patients on antiplatelet (AP) drugs has been increasing; we wanted to assess their impact on the outcome of patients undergoing scheduled TURBT. MATERIALS AND METHODS: A retrospective assessment of noninferiority of 450 consecutive procedures performed between April 2013 and June 2015 was conducted. Patients were divided in two groups: naive or AP drug users. The primary endpoint was the average length of stay (ALOS). Noninferiority was set at 1 day. A subgroup analysis comparing the acetylsalicylic acid (ASA) group and clopidogrel group to the naive group was performed. Multivariate analysis was performed to find the determinants of a longer ALOS. Chi-square or Fisher tests were used to analyze categorical variables, and Student's or Mann-Whitney tests were used to analyze quantitative variables. RESULTS: We included 325 patients who underwent TURBT: 117 received AP drugs (ASA, 85; clopidogrel, 32) and 208 were naive to AP drugs (of whom 117 were consecutively analyzed). The ALOSs were 2.5 days (naive group) and 2.9 days (AP group). The subgroup analysis showed ALOSs of 2.6 days (ASA group) and 3.7 days (clopidogrel group). Clopidogrel therapy (odds ratio = 4.1 [1.7-9.6]) and the duration and depth of resection emerged as determinants of a longer ALOS in multivariate analysis. Perioperative management of AP therapies was achieved according to recommended practices. CONCLUSIONS: The ALOS of patients receiving AP drugs was not clinically different from naive patients. This result was identical for patients receiving ASA. However, clopidogrel increased the length of stay, making us question its use in perioperative management.

Stroke volume changes induced by a recruitment maneuver predict fluid responsiveness in patients with protective ventilation in the operating theater.

During abdominal surgery, the use of protective ventilation with a low tidal volume, positive expiratory pressure (PEEP) and recruitment maneuvers (RMs) may limit the applicability of dynamic preload indices. The objective of the present study was to establish whether or not the variation in stroke volume (SV) during an RM could predict fluid responsiveness.We prospectively included patients receiving protective ventilation (tidal volume: 6 mL kg, PEEP: 5-7 cmH2O; RMs). Hemodynamic variables, such as heart rate, arterial pressure, SV, cardiac output (CO), respiratory variation in SV (ΔrespSV) and pulse pressure (ΔrespPP), and the variation in SV (ΔrecSV) as well as pulse pressure (ΔrecPP) during an RM were measured at baseline, at the end of the RM, and after fluid expansion. Responders were defined as patients with an SV increase of at least 15% after infusion of 500 mL of crystalloid solution.Thirty-seven (62%) of the 60 included patients were responders. Responders and nonresponders differed significantly in terms of the median ΔrecSV (26% [19-37] vs 10% [4-12], respectively; P < 0.0001). A ΔrecSV value more than 16% predicted fluid responsiveness with an area under the receiver-operating characteristic curve (AU) of 0.95 (95% confidence interval [CI]: 0.91-0.99; P < 0.0001) and a narrow gray zone between 15% and 17%. The area under the curve values for ΔrecPP and ΔrespSV were, respectively, 0.81 (95%CI: 0.7-0.91; P = 0.0001) and 0.80 (95%CI: 0.70-0.94; P < 0.0001). ΔrespPP did not predict fluid responsiveness.During abdominal surgery with protective ventilation, a ΔrecSV value more than 16% accurately predicted fluid responsiveness and had a narrow gray zone (between 15% and 17%). ΔrecPP and ΔrespSV (but not ΔrespPP) were also predictive.