Phase lag entropy as a hypnotic depth indicator during propofol sedation.

Phase lag entropy, an electro-encephalography-based hypnotic depth indicator, calculates diversity in temporal patterns of phase relationship. We compared the performance of phase lag entropy with the bispectral index™ in 30 patients scheduled for elective surgery. We initiated a target-controlled infusion of propofol using the Schnider model, and assessed sedation levels using the Modified Observer's Assessment of Alertness/Sedation scale every 30 s with each stepwise increase in the effect-site propofol concentration. Phase lag entropy and bispectral index values were recorded. The correlation coefficient and prediction probability between phase lag entropy or bispectral index and the sedation level or effect-site propofol concentration were analysed. We calculated baseline variabilities of phase lag entropy and bispectral index. In addition, we applied a non-linear mixed-effects model to obtain the pharmacodynamic relationships among the effect-site propofol concentration, phase lag entropy or bispectral index and sedation level. As sedation increased, phase lag entropy and bispectral index both decreased. The prediction probability values of phase lag entropy and bispectral index for sedation levels were 0.697 and 0.700 (p = 0.261) and for the effect-site concentration of propofol were 0.646 and 0.630 (p = 0.091), respectively. Baseline variability in phase lag entropy and bispectral index was 3.3 and 5.7, respectively. The predicted propofol concentrations, using the Schnider pharmacokinetic model, producing a 50% probability of moderate and deep sedation were 1.96 and 3.01 µg.ml-1 , respectively. Phase lag entropy was found to be useful as a hypnotic depth indicator in patients receiving propofol sedation.

Predictive performance of the modified Marsh and Schnider models for propofol in underweight patients undergoing general anaesthesia using target-controlled infusion.

BACKGROUND: : In our preliminary study, the modified Marsh (M-Marsh) model caused an inadvertent underdosing of propofol in underweight patients. However, the predictive performance of the M-Marsh and Schnider models incorporated in commercially available target-controlled infusion (TCI) pumps was not evaluated in underweight patients. METHODS: : Thirty underweight patients undergoing elective surgery were randomly allocated to receive propofol via TCI using the M-Marsh or Schnider models. The target effect-site concentrations (Ces) of propofol were, in order, 2.5, 3, 4, 5, 6 and 2 µg ml -1 . Arterial blood samples were obtained at least 7 min after achieving each pseudo-steady-state. RESULTS: A total of 172 plasma samples were used to determine the predictive performance of both models. The pooled median (95% confidence interval) biases and inaccuracies at a target Ce ≤ 3 µg ml -1 were -22.6 (-28.8 to -12.6) and 31.9 (24.8-36.8) for the M-Marsh model and 9.0 (1.7-16.4) and 28.5 (21.7-32.8) for the Schnider model, respectively. These values at Ce ≥ 4 µg ml -1 were -9.6 (-16.0 to -6.0) and 24.7 (21.1-27.9) for the M-Marsh model and 19.8 (12.9-25.7) and 36.2 (31.4-39.7) for the Schnider model, respectively. CONCLUSIONS: The pooled biases and inaccuracies of both models were clinically acceptable. However, the M-Marsh and Schnider models consistently produced negatively and positively biased predictions, respectively, in underweight patients. In particular, the M-Marsh model showed greater inaccuracy at target Ce ≤ 3 µg ml -1 and the Schnider model showed greater inaccuracy at target Ce ≥ 4 µg ml -1 . Therefore, it is necessary to develop a new pharmacokinetic model for propofol in underweight patients. CLINICAL TRIAL REGISTRATION: KCT0001502.

Outcomes after implementing a tailored endoscopic step-up approach to walled-off necrosis in acute pancreatitis.

BACKGROUND: The aim of the study was to compare the outcomes of patients with pancreatic or peripancreatic walled-off necrosis by endoscopy using the conventional approach versus an algorithmic approach based on the collection size, location and stepwise response to intervention. METHODS: This was an observational before-after study of consecutive patients managed over two time intervals. In the initial period (2004-2009) symptomatic patients with walled-off necrosis underwent conventional single transmural drainage with placement of two stents and a nasocystic catheter, followed by direct endoscopic necrosectomy, if required. In the later period (2010-2013) an algorithmic approach was adopted based on size and extent of the walled-off necrosis and stepwise response to intervention. The main outcome was treatment success, defined as a reduction in walled-off necrosis size to 2 cm or less on CT after 8 weeks. RESULTS: Forty-seven patients were treated in the first interval and 53 in the second. There was no difference in patient demographics, clinical or walled-off necrosis characteristics and laboratory parameters between the groups, apart from a higher proportion of women and Caucasians in the later period. The treatment success rate was higher for the algorithmic approach compared with conventional treatment (91 versus 60 per cent respectively; P < 0·001). On multivariable logistic regression, management based on the algorithm was the only predictor of treatment success (odds ratio 6·51, 95 per cent c.i. 2·19 to 19·37; P = 0·001). CONCLUSION: An algorithmic approach to pancreatic and peripancreatic walled-off necrosis, based on the collection size, location and stepwise response to intervention, resulted in an improved rate of treatment success compared with conventional endoscopic management.

Acute kidney injury after infrarenal abdominal aortic aneurysm surgery: a comparison of AKIN and RIFLE criteria for risk prediction.

BACKGROUND: Although both Acute Kidney Injury Network (AKIN) and risk, injury, failure, loss, and end-stage (RIFLE) kidney disease criteria are frequently used to diagnose acute kidney injury (AKI), they have rarely been compared in the diagnosis of AKI in patients undergoing surgery for infrarenal abdominal aortic aneurysm (AAA). This study investigated the incidence of, and risk factors for, AKI, defined by AKIN and RIFLE criteria, and compared their ability to predict mortality after infrarenal AAA surgery. METHODS: This study examined 444 patients who underwent infrarenal AAA surgery between January 1999 and December 2011. Risk factors for AKI were assessed by multivariable analyses, and the impact of AKI on overall mortality was assessed by a Cox's proportional hazard model with inverse probability of treatment weighting (IPTW). Net reclassification improvement (NRI) was used to assess the performance of AKIN and RIFLE criteria in predicting overall mortality. RESULTS: AKI based on AKIN and RIFLE criteria occurred in 82 (18.5%) and 55 (12.4%) patients, respectively. The independent risk factors for AKI were intraoperative red blood cell (RBC) transfusion and chronic kidney disease (CKD) by AKIN criteria, and age, intraoperative RBC transfusion, preoperative atrial fibrillation, and CKD by RIFLE criteria. After IPTW adjustment, AKI was related to 30 day mortality and overall mortality. NRI was 15.2% greater (P=0.04) for AKIN than for RIFLE criteria in assessing the risk of overall mortality. CONCLUSIONS: Although AKI defined by either AKIN or RIFLE criteria was associated with overall mortality, AKIN criteria showed better prediction of mortality in patients undergoing infrarenal AAA surgery.

Randomized trial comparing fanning with standard technique for endoscopic ultrasound-guided fine-needle aspiration of solid pancreatic mass lesions.

BACKGROUND AND STUDY AIMS: The fanning technique for endoscopic ultrasound-guided fine-needle aspiration (EUS - FNA) involves sampling multiple areas within a lesion with each pass. The aim of this study was to compare the fanning and standard techniques for EUS - FNA of solid pancreatic masses. PATIENTS AND METHODS: Consecutive patients with solid pancreatic mass lesions were randomized to undergo EUS - FNA using either the standard or the fanning technique. The main outcome measure was the median number of passes required to establish diagnosis. The secondary outcome measures were the diagnostic accuracy, technical failure, and complication rate of the two techniques. RESULTS: Of 54 patients, 26 were randomized to the standard technique and 28 to the fanning technique. There was no difference in diagnostic accuracy (76.9 % vs. 96.4 %; P = 0.05), technical failure or complication rates (none in either cohort). There was a significant difference in both the number of passes required to establish diagnosis (median 1 [interquartile range 1 - 3] vs. 1 [1 - 1]; P = 0.02) and the percentage of patients in whom a diagnosis was achieved on pass one (57.7 % vs. 85.7 %; P = 0.02) between the standard and fanning groups, respectively. CONCLUSIONS: The fanning technique of FNA was superior to the standard approach because fewer passes were required to establish the diagnosis. If these promising data are confirmed by other investigators, consideration should be given to incorporating the fanning technique into routine practice of EUS - FNA. Registered at Clinical Trials.gov (NCT 01501903).

Lactate and liver function tests after living donor right hepatectomy: a comparison of solutions with and without lactate.

BACKGROUND: Hyperlactatemia can predict the prognosis of patients undergoing liver resection. The effects of lactated Ringer's solution on liver function have not been evaluated in patients undergoing major liver resection. We therefore compared the effects of two different crystalloid solutions, with and without lactate, on liver function test data and serum lactate level in living donors undergoing right hepatectomy. METHODS: A total of 104 donors undergoing right hepatectomy for liver transplantation were randomly allocated to receive lactated Ringer's (LR) solution (n=52) or Plasmalyte (n=52). Anesthetic and fluid management were standardized. Acid-base status, lactate concentration, and liver function tests were analyzed at predetermined time points during the first 5 post-operative days. RESULTS: The lactate concentrations were significantly higher in the LR group than in the Plasmalyte group 1 h after hepatectomy [4.2 (3.2-5.7) vs. 3.3 (2.6-4.6) mmol/l; P=0.005, median (interquartile ranges)]. In addition, the nadir concentration of albumin was significantly lower and the peak total bilirubin concentration and prothrombin time were significantly higher in the LR group compared with the Plasmalyte group. However, these changes in the LR group subsided within the first or second post-operative days, without apparent complications or prolongation of hospital stay. Post-operative peak concentrations of lactate were not correlated with nadir albumin concentration, peak bilirubin, or peak prothrombin time, in either group. CONCLUSION: This prospective randomized study showed that non-lactate-containing crystalloid solution may have important advantages over LR solution, concerning lactate and liver profiles, in living donors undergoing right hepatectomy.

Assessment of GABA concentration in human brain using two-dimensional proton magnetic resonance spectroscopy.

A quantitative method to assess in vivo brain gamma-aminobutyric acid (GABA) levels is proposed using a J-resolved, two-dimensional (2D) magnetic resonance spectroscopy (MRS) technique. Localized, J-resolved 2D MR spectra were obtained from a 12-cm(3) voxel in the occipital lobe of 36 healthy volunteers (18 male and 18 female, age: 25.1+/-4.8 years). Based on phantom measurements, a GABA resonance peak located at 2.94 ppm, 7.45 Hz, in J-resolved 2D MRS overlaps the least with other resonance peaks which arise from N-acetylaspartate, choline, creatine, glutamate and glutamine. Measurements of this resonance peak yield in vivo GABA concentrations of 1.01+/-0.36 micromol/cm(3) for male and 1.16+/-0.43 micromol/cm(3) for female volunteers, without correction for T1 and T2 relaxation effects. These results are in good agreement with previously reported data and suggest that, with further development, 2D MRS may provide a practical means to estimate the concentration of this important neurotransmitter.

Increased B-type natriuretic peptide during liver transplantation: relationship to invasively measured hemodynamic parameters.

BACKGROUND: The role of B-type natriuretic peptide (BNP) concentration in predicting cardiac dysfunction has been extensively investigated in many clinical conditions. Little is known, however, about its relationships with hemodynamic parameters from right heart catheterization in patients undergoing liver transplant surgery. METHODS: We retrospectively evaluated 525 patients who underwent liver transplantation. Hemodynamic variables from a Swan-Ganz catheter and BNP concentrations were measured 1 hour after induction of general anesthesia. Patients were stratified by quintiles of BNP concentrations. Univariate and multivariate logistic regression analysis were used to identify hemodynamic parameters associated with BNP ≥ 135 pg/mL, a cutoff point for the 5th quintile. RESULTS: Univariate analysis showed that factors significantly associated with BNP ≥ 135 pg/mL included model for end-stage liver disease (MELD) score, diastolic blood pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP), cardiac index, right ventricular end-diastolic volume index (RVEDVI), systemic vascular resistance index, pulmonary vascular resistance index (PVRI), and right ventricular stroke work index. Multivariate analysis revealed that MELD score (odds ratio [OR] = 1.059, P < .001), PCWP (OR = 1.116, P = .026), RVEDVI (OR = 1.010, P = .009), and PVRI (OR = 1.009, P = .002) were independent determinants of BNP ≥ 135 pg/mL. CONCLUSIONS: Severity of liver disease, preload dependent hemodynamic parameters, and pulmonary vascular resistance were found to be significantly associated with increased BNP concentration, reinforcing the utility of BNP as a marker of cardiac strain and ventricular volume overload in liver failure patients undergoing liver transplant surgery.

Effect of propranolol on the relationship between QT interval and vagal modulation of heart rate variability in cirrhotic patients awaiting liver transplantation.

BACKGROUND: Prolonged corrected QT (QT(c)) interval and vagal dysfunction are common occurrences in liver cirrhosis and are determinants of mortality in patients with chronic liver disease. We evaluated whether propranolol can affect the relationship between QT(c) interval and cardiac vagal control of heart rate variability (HRV) in cirrhotic patients awaiting liver transplantation. METHODS: We compared 50 cirrhotic patients (M/F = 43/7, 52.6 ± 8.4 years, Child-Pugh class A/B/C: 9/24/17) receiving propranolol with a sex-, age-, and liver disease severity-matched control group of 50 patients (M/F = 43/7, 52.0 ± 8.3 year, Child-Pugh class A/B/C: 9/24/17) not receiving propranolol. Among the parameters evaluated were QT(c) interval and cardiac vagal indices of HRV, including the root mean square of successive differences in R-R intervals (RMSSD); spectral power in the high-frequency range (HF); standard deviation (SD)1 in Poincare plot; and sample entropy. Correlations between QT(c) interval and vagal indices of HRV were analyzed. RESULTS: The mean duration of preoperative propranolol treatment in the propranolol group was 19.4 ± 24.7 months. QT(c) interval was significantly lower, whereas RMSSD, HF, SD1, and sample entropy were significantly higher in the propranolol group than in the control group. Correlation coefficients between QT(c) interval and RMSSD, HF, SD1, and sample entropy were higher in the propranolol group than in the control group. CONCLUSIONS: The prolonged QT(c) interval observed in cirrhotic patients may be reduced by propranolol administration, an effect attributable to improved vagal cardiac modulation. These findings suggest that propranolol may have a beneficial effect on perioperative mortality in cirrhotic patients awaiting liver transplantation.

A retrospective case-control study of intraoperative cardiac dysfunction in elderly patients (≥60 years) undergoing live donor liver transplantation.

BACKGROUND: The age range of patients accepted for the orthotopic liver transplantation (OLT) has widened. Concerns have arisen, therefore, about the ability of the hearts of elderly patients to manage these stressful conditions. The aim of this study was to investigate the preoperative echocardiographic findings and the intraoperative cardiac dysfunction among elderly cirrhotic recipients undergoing live donor OLT. METHODS: In this retrospective case-control study we evaluated clinical data, echocardiography, and intraoperative right-sided heart hemodynamic measurements from 2007 and 2009 among 56 recipients aged at least 60 years who were matched for gender and the severity of cirrhosis. Intraoperative cardiac dysfunction was defined as a decreased left ventricular stroke work index despite an increase in right ventricular end diastolic volume index (RVEDVI) or pulmonary artery occlusion pressure (PAOP). We compared measurements at predetermined times during the anhepatic and neohepatic periods with those at baseline. RESULTS: Older recipients (mean, 63 years; range, 60-69) showed significantly reduced early diastolic annular velocity (E'), early maximal ventricular filling velocity (E)/late filling velocity (A) ratio, and increased A on echocardiography versus younger recipients (mean 48 years; range, 31-56). We observed negative correlation between age and E' (r = -0.44; P < .001) and a positive correlation between age and E/E' (r = 0.31; P < .01). The incidence of intraoperative cardiac dysfunction did not differ between case and control groups with an increase of RVEDVI (11.4% vs 10.6%) or PAOP (27.2% vs 25.0%) during the anhepatic and neohepatic periods. A higher proportion of older recipients needed inotropic agents during OLT (60.7% vs 39.3%; P = .04). CONCLUSIONS: OLT patients of ar least 60 years of age may not show a greater incidence of cardiac dysfunction during OLT versus younger ones, although older recipients showed reduced diastolic function and more frequently required inotropic support.

Can a warning leak in a patient with unruptured aneurysm mask an underlying gastrointestinal pathology? A case report.

Aggravating headache accompanied by nausea and epigastric discomfort suggesting a warning leak in a 39-year-old woman with a giant thrombosed intracranial aneurysm prompted us to undertake coiling of the aneurysm. After uneventful coil embolization of the aneurysm, collapse of the lung related to bronchospam developed, and was found to have a gastrointestinal pathology which had gone undetected before the procedure. Despite its rarity, gastrointestinal pathology mimicking warning leak should have been considered in a patient with a warning leak sign.