Pleth variability index versus pulse pressure variation for intraoperative goal-directed fluid therapy in patients undergoing low-to-moderate risk abdominal surgery: a randomized controlled trial.

BACKGROUND: Goal-directed fluid therapy (GDFT) based on dynamic indicators of fluid responsiveness has been shown to decrease postoperative complications and hospital length of stay (LOS) in patients undergoing major abdominal surgery. The usefulness of this approach still needs to be clarified in low-to-moderate risk abdominal surgery. Both pulse-pressure variation (PPV) and pleth variability index (PVI) can be used to guide GDFT strategies. The objective of this prospective randomized controlled trial was to determine if the use of PVI guided GDFT, when compared to PPV guided GDFT, would lead to similar hospital LOS in patients undergoing low-to-moderate risk surgery. Secondary outcomes included amount of fluid administered and incidence of postoperative complications. METHODS: Patients were randomized into either PVI or PPV guided GDFT groups. Both received a baseline 2 ml kg- 1 h- 1 Lactated Ringer infusion. Additional fluid boluses consisted of 250 mL of colloid that was infused over a 10 min period if PVI was > 15% or PPV was > 13% for at least five minutes. The primary outcome was to determine if hospital LOS, which was defined as the number of days from surgery up to the day the surgeon authorized hospital discharge, was equivalent between the two groups. RESULTS: A total of 76 patients were included and they were randomized into two groups of 38 patients. Baseline characteristics were similar in both groups. Both PVI and PPV guided GDFT strategies were equivalent for the primary outcome of LOS (median [interquartile range]) (days) 2.5 [2.0-3.3] vs. 3.0 [2.0-5.0], p = 0.230, respectively. Fluids infused, postoperative complications, and all other outcomes were not different between groups. CONCLUSION: In patients undergoing low-to-moderate risk abdominal surgery, PVI seems to guide GDFT similarly to PPV in regards to hospital LOS, amount of fluid, and incidence of postoperative complications. However, in low-risk patients undergoing these surgical procedures optimizing stroke volume may have limited impact on outcome. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02908256 , September 2016, retrospectively registered.

Impact of entropy monitoring on volatile anesthetic uptake.

BACKGROUND: Electroencephalogram-derived monitoring to assess anesthetic depth may allow more accurate hypnotic drug administration, resulting in decreased anesthetic drug consumption. The authors hypothesized that the use of M-Entropy monitoring (Datex-Ohmeda, Helsinki, Finland) is associated with reduced sevoflurane uptake (primary outcome) in patients undergoing major abdominal surgery. METHODS: A total of 50 patients with an American Society of Anesthesiology score of II-III, scheduled for elective laparoscopic rectosigmoidectomy were randomized into two groups in this randomized controlled trial. In the control group, the target expiratory fraction of sevoflurane was adapted according to standard clinical practice. In the study group, the target expiratory fraction of sevoflurane was adapted to maintain state entropy values between 40 and 60. State entropy values were continuously recorded in both groups but were not available to the anesthesiologist in the control group. In both groups, patients were ventilated using the auto-control mode of the Zeus® (Dräger, Lübeck, Germany) respirator, which allows precise measurements of sevoflurane uptake. Sufentanil was administered using a target-controlled infusion system. RESULTS: Demographics did not differ between groups. During the anesthesia maintenance phase, state entropy values were lower in the control group than the study group (P < 0.0001). Sevoflurane uptake was higher in the control group than the study group (5.2 ± 1.4 ml/h vs. 3.8 ± 1.5 ml/h; P = 0.0012). Three patients in the control group developed intraoperative hypotension compared with none in the study group (P = 0.03). CONCLUSIONS: Monitoring the depth of anesthesia using M-Entropy was associated with a significant reduction in sevoflurane uptake.

A randomised trial comparing sufentanil versus remifentanil for laparoscopic gastroplasty in the morbidly obese patient.

BACKGROUND AND OBJECTIVE: This prospective, randomised double-blind study compared the effects of target control infusion (TCI) of sufentanil and remifentanil on the quality of recovery and post-operative pain control in morbidly obese patients undergoing laparoscopic gastroplasty. METHODS: Following institutional Ethics Committee approval and written informed consent, 100 morbidly obese patients were randomised to receive either TCI sufentanil (0.3 ng ml⁻¹; S-group; N = 50) or TCI remifentanil (3 ng ml⁻¹; R-group; N = 50) in combination with desflurane (O2/air mixture: FiO2, 50%). Quality of recovery was estimated by means of the modified Aldrete score and by the ability to perform psychomotor tests with the same competence post-operatively as pre-operatively. Post-operative pain was evaluated by the quantity of piritramide needed to achieve a visual analogue scale (VAS) less than 3. Statistical analysis was performed using an unpaired Student's t-test, Mann-Whitney U-test and χ² test, as appropriate. RESULTS: Patient and surgical characteristics were similar among groups. In the R-group, time to extubation was significantly shorter, but VAS significantly higher than that in the S-group (P < 0.01). Quality of recovery and duration of post-anaesthesia care unit stay were comparable between groups (S-group: 119 ± 27 min and R-group: 119 ± 35 min). Piritramide consumption during the first 4 post-operative hours was higher in the R-group than in the S-group [S-group (median, range): 11.5 mg, 5.5-16.0; R-group: 18.0 mg, 14-22, P < 0.01], but not later on. CONCLUSION: In the conditions of the present study, although TCI sufentanil resulted in slower awakening than TCI remifentanil, it was associated with a better quality of recovery.

Effect of pneumoperitoneum on dynamic variables of fluid responsiveness (Delta PP and PVI) during Trendelenburg position.

BACKGROUND AND AIMS: Pulse pressure variation (ΔPP) is considered as one of the best predictors of fluid responsiveness in patients under mechanical ventilation. Pleth Variability Index (PVI) has been proposed as a noninvasive alternative. However, pneumoperitoneum has been recently suggested as a limitation to their interpretation. The aim of this study was to compare changes in ΔPP and PVI related to autotransfusion associated with a Trendelenburg maneuver before and during pneumoperitoneum. METHODS: 50 patients undergoing elective abdominal laparoscopic surgery were enrolled in this prospective observational study. All patients were equipped with an invasive radial artery catheter and a PVI probe. After obtaining a stable signal with both ΔPP and PVI, baseline values were recorded, before and after head-down tilts of 10°, with or without abdominal insufflation (10-12 mmHg). All measurements were made before any fluid challenge under standardized anaesthesia, while patients were paralyzed and mechanically ventilated with 8 mL/kg tidal volume. RESULTS: Changes in ΔPP and PVI associated with the Trendelenburg maneuver before and after insufflation of the pneumoperitoneum were significantly different (P < 0.001). In baseline conditions, the Trendelenburg maneuver was associated with a significant decrease in heart rate while mean arterial pressure remained unchanged. Both ΔPP and PVI decreased. After insufflation of the pneumoperitoneum, the Trendelenburg maneuver was associated with a significant decrease in heart rate and ΔPP and an increase in mean arterial pressure while PVI remained unchanged. CONCLUSION: Pneumoperitoneum did not alter the response of ΔPP to autotransfusion associated with the Trendelenburg maneuver, which was not the case for the PVI. This latter decreased during Trendelenburg maneuver performed alone and remained unchanged during Trendelenburg maneuver performed after insufflation of the pneumoperitoneum.

Does Lung Compliance Optimization Through PEEP Manipulations Reduce the Incidence of Postoperative Hypoxemia in Laparoscopic Bariatric Surgery? A Randomized Trial.

BACKGROUND: In obese patients (OP), the best intraoperative ventilation strategy remains to be defined. Dynamic lung compliance (Cdyn) and dead space fraction are indicators of efficient ventilation at an optimal positive end-expiratory pressure (PEEP). Herein, we investigated whether intraoperative dynamic lung compliance optimization through PEEP manipulations affects the incidence of postoperative hypoxemia (SpO2 < 90%) in OP undergoing laparoscopic bariatric surgery (LBS). METHODS: This was a single-center, prospective, randomized controlled study conducted from July 2013 to December 2015. After obtaining institutional review board approval and informed consent, 100 OP undergoing LBS under volume-controlled ventilation (tidal volume 8 mL/kg of ideal body weight) were randomized according to the PEEP level maintained during the surgery. In the control group, a PEEP of 10 cm H2O was maintained, while in the intervention group, the PEEP was adapted to achieve the best dynamic lung compliance. Anesthesia and analgesia were standardized. The patients received supplemental nasal oxygen on the first postoperative day and were monitored up to the second postoperative day with a portable pulse oximeter. RESULTS: Demographics were similar between groups. There was no difference in the incidence of hypoxemia during the first 2 postoperative days (control: 1.3%; intervention: 2.1%; p = 0.264). CONCLUSIONS: The incidence of postoperative hypoxemia was not reduced by an open-lung approach with protective ventilation strategy in obese patients undergoing LBS. A pragmatic application of a PEEP level of 10 cm H2O was comparable to individual PEEP titration in these patients. TRIAL REGISTRATION: Clinicaltrials.gov identifier, NCT02579798; https://clinicaltrials.gov/ct2/show/NCT02579798.

Artificially enriching the training dataset of statistical shape models via constrained cage-based deformation.

The construction of a powerful statistical shape model (SSM) requires a rich training dataset that includes the large variety of complex anatomical topologies. The lack of real data causes most SSMs unable to generalize possible unseen instances. Artificial enrichment of training data is one of the methods proposed to address this issue. In this paper, we introduce a novel technique called constrained cage-based deformation (CCBD), which has the ability to produce unlimited artificial data that promises to enrich variability within the training dataset. The proposed method is a two-step algorithm: in the first step, it moves a few handles together, and in the second step transfers the displacements of these handles to the base mesh vertices to generate a real new instance. The evaluation of statistical characteristics of the CCBD confirms that our proposed technique outperforms notable data-generating methods quantitatively, in terms of the generalization ability, and with respect to specificity.

Delay and its related factors in seeking treatment in patients with acute myocardial infarction.

BACKGROUND: Early diagnosis and treatment of myocardial infarction can prevent life-threatening complications such as dysrhythmias and death. The aim of this study was to determine the length of delay and its related factors in seeking treatment among a group of patients with myocardial infarction. METHODS: In a cross-sectional design, all the patients who had referred to a general teaching hospital (Kashan, Iran) for treatment of myocardial infarction from April 2004 to March 2005 were recruited. Demographic characteristics, the amount of delay, and the causes of having delay were recorded. RESULTS: Two hundred patients were recruited for this study from which 131 (69%) patients had delay in seeking treatment. Factors such as gender, age, economical status, educational level, referring to a general physician before referring to the hospital, the severity of symptoms, residential place (urban vs. rural), and the time of the onset of the symptoms (day vs. night) were determined to be related to having delay. The most important causes of having delay were: "hoping the symptoms to alleviate spontaneously", "attributing the symptoms to other problems other than heart problems", and "disregarding the symptoms". CONCLUSION: Regarding the most important causes of having delay in this study, the importance of educating people about the symptoms of myocardial infarction and the importance of early referral to the hospitals is clarified.

Correction of oral contrast artifacts in CT-based attenuation correction of PET images using an automated segmentation algorithm.

PURPOSE: Oral contrast is usually administered in most X-ray computed tomography (CT) examinations of the abdomen and the pelvis as it allows more accurate identification of the bowel and facilitates the interpretation of abdominal and pelvic CT studies. However, the misclassification of contrast medium with high-density bone in CT-based attenuation correction (CTAC) is known to generate artifacts in the attenuation map (mumap), thus resulting in overcorrection for attenuation of positron emission tomography (PET) images. In this study, we developed an automated algorithm for segmentation and classification of regions containing oral contrast medium to correct for artifacts in CT-attenuation-corrected PET images using the segmented contrast correction (SCC) algorithm. METHODS: The proposed algorithm consists of two steps: first, high CT number object segmentation using combined region- and boundary-based segmentation and second, object classification to bone and contrast agent using a knowledge-based nonlinear fuzzy classifier. Thereafter, the CT numbers of pixels belonging to the region classified as contrast medium are substituted with their equivalent effective bone CT numbers using the SCC algorithm. The generated CT images are then down-sampled followed by Gaussian smoothing to match the resolution of PET images. A piecewise calibration curve was then used to convert CT pixel values to linear attenuation coefficients at 511 keV. RESULTS: The visual assessment of segmented regions performed by an experienced radiologist confirmed the accuracy of the segmentation and classification algorithms for delineation of contrast-enhanced regions in clinical CT images. The quantitative analysis of generated mumaps of 21 clinical CT colonoscopy datasets showed an overestimation ranging between 24.4% and 37.3% in the 3D-classified regions depending on their volume and the concentration of contrast medium. Two PET/CT studies known to be problematic demonstrated the applicability of the technique in clinical setting. More importantly, correction of oral contrast artifacts improved the readability and interpretation of the PET scan and showed substantial decrease of the SUV (104.3%) after correction. CONCLUSIONS: An automated segmentation algorithm for classification of irregular shapes of regions containing contrast medium was developed for wider applicability of the SCC algorithm for correction of oral contrast artifacts during the CTAC procedure. The algorithm is being refined and further validated in clinical setting.