Predictors of Perioperative Acute Kidney Injury in Obese Patients Undergoing Laparoscopic Bariatric Surgery: a Single-Centre Retrospective Cohort Study.

BACKGROUND: Obesity has been associated with increased risk of perioperative acute kidney injury (AKI). We aim to establish the incidence of AKI among patients undergoing laparoscopic bariatric surgery and identify potential risk factors. METHODS: Records of 1230 patients who underwent laparoscopic bariatric surgery in a tertiary centre from 1 December 2009 to 31 January 2014 were retrospectively studied. AKI diagnosis was made by comparing the baseline and post-operative serum creatinine to determine the presence of predefined significant change based on the Kidney Disease: Improving Global Outcomes (KDIGO) definition. Univariate analyses were performed to determine significant clinical factors, and multiple logistic regression analysis was subsequently done to determine independent predictors of AKI. RESULTS: Thirty-five (2.9 %) patients developed AKI during the first 72 h post-surgery. Multivariate logistic regression analysis revealed impaired renal function (OR 10.429, 95 % CI 3.560 to 30.552), use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (OR 3.038, 95 % CI 1.352 to 6.824), and body mass index (OR 1.048, 95 % CI 1.005 to 1.093) as independent predictors of perioperative acute kidney injury in the obese patients who underwent laparoscopic bariatric surgery. CONCLUSIONS: We found that the incidence of perioperative AKI among patients who underwent laparoscopic bariatric surgery is at 2.9 %. Impaired renal function, use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and raised body mass index were found to be independent predictors of AKI. Patients with these risk factors could be considered at risk for developing perioperative AKI, and extra perioperative vigilance should be undertaken.

Neutrophil Lymphocyte Ratio as a predictor of systemic inflammation - A cross-sectional study in a pre-admission setting.

BACKGROUND: Neutrophil:lymphocyte ratio (NLR)  is an emerging biomarker that is used to predict postoperative mortality and morbidity in cardiac and cancer surgeries. The association of this biomarker with systemic illness and its usefulness in risk assessment of preoperative patients has not been fully elucidated. OBJECTIVES: To determine the prevalence of elevated NLR in preoperative patients and to examine the relationship between elevated NLR and the presence of systemic illnesses as well as anaesthesia risk indices such as American Society of Anesthesia (ASA) and the revised cardiac risk index (RCRI) scores.   DESIGN: Cross-sectional study Setting: Anaesthesia pre-admission clinic, Toronto Western Hospital, Toronto, Canada Patients: We evaluated 1117 pre-operative patients seen at an anesthesia preadmission clinic. RESULTS: NLR was elevated (>3.3) in 26.6% of target population. In multivariate analysis, congestive cardiac failure, diabetes mellitus and malignancy were independent risk factors predicting raised NLR. After regression analysis, a relationship between NLR and ASA score (Odds Ratio 1.78; 95% CI: 1.42-2.24) and revised cardiac risk index (RCRI, odds ratio 1.33; 95% CI: 1.09-1.64, p-value: 0.0063) was observed. CONCLUSIONS:  NLR was elevated (> 3.3) in 26.6% of patients. Congestive cardiac failure and malignancy were two constant predictors of elevated NLR at >3.3 and > 4.5. There was a strong association between NLR and anesthesia risk scoring tools of ASA and RCRI.

Neutrophil-lymphocyte ratio as predictor of mortality and morbidity in cardiovascular surgery: a systematic review.

BACKGROUND: Neutrophil-lymphocyte ratio (NLR) is an emerging biomarker of inflammation and predicts poorer outcome in cancer surgery. The prognostic value of NLR in cardiovascular surgery is unclear. METHODS: Systematic review and meta-analysis of studies of in cardiovascular surgical patients were conducted to assess the role of perioperative NLR in predicting post-operative mortality and morbidity. Electronic searches were conducted on Ovid Medline, EMBASE, Cochrane Central Register of Controlled Trials and Cochrane Database of Systemic Reviews for all prospective clinical studies reporting on NLR and post-operative morbidity and mortality in cardiovascular surgical patient population. Our primary end point was all-cause post-operative mortality and the secondary end point was post-operative morbidity. Mortality outcome from prospective studies were pooled for a meta-analysis using a random-effect model. RESULTS: Of the 999 citations identified, five studies with 3487 patients met the inclusion criteria. In a pooled analysis of three prospective studies of 3108 patients, a preoperative increase in NLR (>3.3 in cardiac surgery, >5 in vascular surgery) was associated with increased mortality at a mean follow-up of 34.8 months (hazard ratio 1.85, 95% confidence interval 1.46-2.36; P < 0.00001). Raised NLR value was also associated with increased cardiac mortality, amputation in vascular operations and raised risk of post-operative re-intubation. CONCLUSIONS: Elevated NLR were associated with increased long-term mortality and morbidity after major cardiac and vascular surgery. NLR may guide perioperative management and risk-stratification of patients.

Improving the C-MAC video laryngoscopic view when applying cricoid pressure by allowing access of assistant to the video screen.

Cricoid pressure, as part of rapid sequence induction, may on occasion worsen laryngoscopic views and intubating conditions. We investigated whether allowing the assistant applying cricoid pressure to view the video laryngoscope screen would improve the laryngoscopic views compared to when they were blinded to the video screen. Laryngoscopy using the C-MAC video laryngoscope was performed in 51 patients undergoing elective general anaesthesia. Photographs were recorded sequentially under the following conditions: A) cricoid pressure by an assistant unable to see the video monitor, and B) cricoid pressure optimised by an assistant able to see the video monitor. These photographs were analysed offline by assessors blinded to whether the photo was obtained with blinded or non-blinded cricoid pressure application. Subjectively, 41% of views were improved when the assistant applying cricoid pressure was able to see the C-MAC screen, compared to those unable to see the screen. The view was unchanged in 45%, but initially worsened in 14%. These findings suggest that assistants applying cricoid pressure when a C-MAC is used should have access to the video image, but must also respond to requests for change from the person performing the intubation.

I(f) channel inhibitor ivabradine lowers heart rate in mice with enhanced sympathoadrenergic activities.

1. Ivabradine selectively reduces heart rate (HR) by inhibiting the cardiac pacemaker I(f) current, thus prolonging the duration of spontaneous depolarization in the sinus node. The activity of ivabradine under conditions of enhanced sympathoadrenergic activity has been addressed by investigating the effects of repeated oral administration in mice with sympathoadrenergic activation due to either stress, cardiac-restricted overexpression of beta(2)-adrenergic receptors (beta(2)AR), or beta-agonist administration. HR and left ventricular fractional shortening (FS) were determined by echocardiography. 2. Initial experiments showed that the conscious restrained state was associated with stress-mediated sympathetic activation, while sympathetic withdrawal occurred under anaesthetized conditions. In wild-type mice, ivabradine reduced HR under both conscious and anaesthetized states, with a similar degree in absolute reduction under both states. FS was unchanged by the treatment. 3. Ivabradine was similarly effective in reducing HR in the beta(2)AR transgenic mice. Further, ivabradine at 10 mg kg(-1) day(-1) reduced the maximal HR increase in response to the beta-agonist isoproterenol, without modifying the response of contractile parameters. 4. These data indicate that oral administration of ivabradine in mice reduces HR while ventricular performance is maintained. This specific HR-reducing action of ivabradine is well preserved under conditions that are associated with significant activation of the sympathoadrenergic system.

Assessment of cardiac function by echocardiography in conscious and anesthetized mice: importance of the autonomic nervous system and disease state.

In this study, the authors sought to evaluate the mechanisms responsible for echocardiographically determined differences in cardiac structure and function between conscious and anesthetized mice to determine whether such differences were more or less evident in diseased states. Cardiac parameters were determined by transthoracic echocardiography. Mice anesthetized with a mixture of ketamine and xylazine showed reductions in heart rate (HR, 252 +/- 16 beats/min versus 734 +/- 9 beats/min) and fractional shortening (FS, 35% +/- 2% versus 59% +/- 2%) compared with conscious mice. Conscious mice responded little to the beta-agonist isoproterenol or atropine, but showed profound reductions in HR and FS in response to the beta(1)-antagonist atenolol. In contrast, both isoproterenol and atropine led to increases in HR and FS in anesthetized mice. The stress in conscious animals was reduced by the sedative midazolam, leading to partial restoration of responses to isoproterenol. Mice with constitutive activation of the beta-adrenergic system, due to cardiac overexpression of beta(2)-adrenergic receptors or with heart disease (myocardial infarct and pressure-overload hypertrophy) showed few differences in functional parameters between conscious and anesthetized states, attributable to pre-existing activation of the sympathetic and beta-adrenergic systems, even during anesthesia. The results indicate that the autonomic nervous system plays a critical role in the observed differences in cardiac structure and function between anesthetized and conscious mice.