Effect of statins on insulin requirements during non-cardiac surgery.

Statins are thought to potentially impair glucose metabolism, increasing plasma glucose concentration. The effect of prolonged statin use on glucose metabolism among outpatients is thus well established. However, the impact of statin use on glucose concentrations and insulin requirements during surgery remains poorly characterised and may very well differ considering the substantial hyperglycaemic stress response to surgery. We conducted a study to test the hypothesis that patients taking statins preoperatively require more intraoperative insulin than non-users. We analysed 173 adults having major non-cardiac surgery who participated in the Dexamethasone, Light Anaesthesia and Tight Glucose Control Trial between 2007 and 2010. We compared statin and non-statin users on total amount of intraoperative insulin to maintain plasma glucose concentration within 4.4 to 6.1 mmol/l using the inverse propensity score weighting method. Sixty-seven patients were statin users and 106 were non-statin users. The estimated ratio of geometric means between the statin users and the non-users was 1.45 (95% confidence interval: 0.93, 2.26, statin versus non-statin, P=0.11). The total amount of intraoperative insulin usage did not differ significantly among patients taking different types of statins (P=0.50). While the total amount of intraoperative insulin used was not statistically different between the statin users and non-users, we observed a potentially important trend toward insulin resistance intraoperatively among statin users during major non-cardiac surgery. This result is consistent with non-operative settings and cardiac surgery. Further investigation is essential to determine whether this effect is real and, if so, determine which specific statins are more associated with insulin resistance.

Preoperative blood glucose concentrations and postoperative outcomes after elective non-cardiac surgery: an observational study.

BACKGROUND: The association between preoperative blood glucose (BG) concentration and outcomes after non-cardiac surgery and the impact of the diabetes diagnosis status remain unclear. We tested two hypotheses: that preoperative BG is related to surgical outcomes; and that this relationship depends on the diabetes diagnosis status of the patient. METHODS: We retrospectively analysed data on 61 536 consecutive elective non-cardiac surgery patients treated at our tertiary care facility. Logistic regression models were used to test the hypotheses before and after adjustment for baseline patient characteristics. Our primary outcome was a composite of in-hospital serious complications and mortality. A second primary outcome was 1 yr mortality. RESULTS: The crude incidence of the composite in-hospital outcome was significantly related to preoperative BG (P<0.001), but not after covariable adjustment (P=0.40). This relationship did not significantly differ between patients with and without diagnosed diabetes (P=0.09). One year mortality was significantly related to preoperative BG, both univariably (P<0.001) and after covariable-adjustment (P<0.001). Patients with diagnosed diabetes and preoperative euglycaemia generally had worse 1 yr mortality than those without diabetes at the same BG {e.g. odds ratio (OR) [95% confidence interval (CI)] of 1.27 (1.06, 1.53) at 6 mmol litre(-1) (108 mg dl(-1)), P=0.003}. Conversely, hyperglycaemic patients with diagnosed diabetes displayed a significantly lower 1 yr mortality than hyperglycaemic patients without diabetes [OR (95% CI) of 0.58 (0.44, 0.77) at 12 mmol litre(-1) (216 mg dl(-1)), P<0.001]. CONCLUSIONS: For elective non-cardiac surgery, preoperative hyperglycaemia should be given greater consideration in patients without diabetes than in those with diagnosed diabetes.

Dexamethasone, light anaesthesia, and tight glucose control (DeLiT) randomized controlled trial.

BACKGROUND: The inflammatory response to surgical tissue injury is associated with perioperative morbidity and mortality. We tested the primary hypotheses that major perioperative morbidity is reduced by three potential anti-inflammatory interventions: (i) low-dose dexamethasone, (ii) intensive intraoperative glucose control, and (iii) lighter anaesthesia. METHODS: We enrolled patients having major non-cardiac surgery who were ≥40 yr old and had an ASA physical status ≤IV. In a three-way factorial design, patients were randomized to perioperative i.v. dexamethasone (a total of 14 mg tapered over 3 days) vs placebo, intensive vs conventional glucose control 80-110 vs 180-200 mg dl(-1), and lighter vs deeper anaesthesia (bispectral index target of 55 vs 35). The primary outcome was a collapsed composite of 15 major complications and 30 day mortality. Plasma high-sensitivity (hs) C-reactive protein (CRP) concentration was measured before operation and on the first and second postoperative days. RESULTS: The overall incidence of the primary outcome was about 20%. The trial was stopped after the second interim analysis with 381 patients, at which all three interventions crossed the futility boundary for the primary outcome. No three-way (P=0.70) or two-way (all P>0.52) interactions among the interventions were found. There was a significantly smaller increase in hsCRP in patients given dexamethasone than placebo [maximum 108 (64) vs 155 (69) mg litre(-1), P<0.001], but none of the other two interventions differentially influenced the hsCRP response to surgery. CONCLUSIONS: Among our three interventions, dexamethasone alone reduced inflammation. However, no intervention reduced the risk of major morbidity or 1 yr mortality. TRIAL REGISTRATION IDENTIFIER: NCT00433251 at www.clinicaltrials.gov.

Intraoperative tissue oxygenation and postoperative outcomes after major non-cardiac surgery: an observational study.

BACKGROUND: The relationship between tissue oxygen saturation (StO(2)) and serious postoperative complications remains unclear. We tested the hypothesis that perioperative in patients undergoing major non-cardiac surgery is inversely related to serious surgical outcomes. METHODS: We enrolled 124 patients, ASA physical status ≤IV, having elective major non-cardiac surgeries with general anaesthesia. An InSpectra Model 650 StO(2) monitor (Hutchinson Technology, Hutchinson, MN, USA) was used to measure at the thenar eminence throughout surgery and for two postoperative hours. Our primary outcome was a composite of 30 day mortality and serious in-hospital complications. The secondary outcome was an a priori subset of the primary composite outcome representing infectious and wound-healing complications. Multivariable logistic regression was used to evaluate the associations between our primary and secondary outcomes and time-weighted average (TWA) and minimum . RESULTS: Patients were 61 (12), mean (SD) yr old. The minimum was inversely associated with our primary composite outcome (P=0.02). The estimated odds ratio (97.5% CI) of having any major postoperative morbidity was 0.82 (0.67, 1.00) for a 5% increase in the minimum . In contrast, TWA was not significantly associated with major postoperative morbidity (P=0.35). Furthermore, neither TWA (P=0.65) nor minimum (P=0.70) was significantly associated with wound complications. CONCLUSIONS: Minimum perioperative peripheral tissue oxygenation predicted a composite of major complications and mortality from major non-cardiac surgery. This is an observational association and whether clinical interventions to augment tissue oxygenation will improve outcomes remains to be determined.

Neurological biomarkers in the perioperative period.

The rapid detection and evaluation of patients presenting with perioperative neurological dysfunction is of great clinical relevance. Biomarkers have been defined as biological molecules that can be used as an indicator of new onset or progression of a biological process or effect of treatment. Biomarkers have become increasingly important in this setting to supplement other modalities of diagnosis such as EEG, sensory- or motor-evoked potential, transcranial Doppler, near-infrared spectroscopy, or imaging methods. A number of neuro-proteins have been identified and are currently under investigation for potential to provide insights into injury severity, outcome, and the ability to monitor cellular damage and molecular events that occur during neurological injury. S100B is a protein released by glial cells and is considered a marker of blood-brain barrier dysfunction. Clinical studies in patients undergoing cardiac and non-cardiac surgery indicate that serum levels of S100B are increased intraoperatively and after operation. The neurone-specific enolase has also been extensively investigated as a potential marker of neuronal injury in the context of cardiac and non-cardiac surgery. A third biomarker of interest is the Tau protein, which has been linked to neurodegenerative disorders. Tau appears to be more specific than the previous two biomarkers since it is only found in the central nervous system. The metalloproteinase and ubiquitin C terminal hydroxylase-L1 (UCH-L1) are the most recently researched markers; however, their usefulness is still unclear. This review presents a comprehensive overview of S100B, neuronal-specific enolase, metalloproteinases, and UCH-L1 in the perioperative period.

GlideScope® vs flexible fibreoptic scope for elective intubation in obese patients.

We hypothesised that in obese patients, tracheal intubation with the GlideScope® would be advantageous compared with flexible fibreoptic intubation. Seventy-five anaesthetised obese patients were randomly assigned to oral intubation by either GlideScope or flexible fibreoptic bronchoscope. We compared the two devices for time to intubate (p = 0.19), difficulty of intubation (p = 0.58), successful intubation on first attempt (p = 0.29), number of attempts (p = 0.24), incidence of hypoxaemia (p = 0.57), amount of post-intubation bleeding (p = 0.79) and sore throat (p = 0.82). None differed significantly. Median (IQR [range]) time to intubation was 37 (25-48 [19-81]) s and 95% of the first attempts were successful with the GlideScope, vs 43 (35-58 [26-96]) s and an 86% first-attempt success rate with the flexible fibreoptic bronchoscope. For experienced users, the time required to intubate the trachea in anaesthetised obese patients is similar with the GlideScope and a flexible bronchoscope.

Analysis of risk factors for myocardial infarction and cardiac mortality after major vascular surgery.

BACKGROUND: Patients undergoing vascular surgical procedures are at high risk for perioperative myocardial infarction (PMI). This study was undertaken to identify predictors of PMI and in-hospital death in major vascular surgical patients. METHODS: From the Vascular Surgery Registry (6,948 operations from January 1989 through June 1997) the authors identified 107 patients in whom PMI developed during the same hospital stay. Case-control patients (patients without PMI) were matched at a 1x:x1 ratio with index cases according to the type of surgery, gender, patient age, and year of surgery. The authors analyzed data regarding preoperative cardiac disease and surgical and anesthetic factors to study association with PMI and cardiac death. RESULTS: By using univariable analysis the authors identified the following predictors of PMI: valvular disease (P = 0.007), previous congestive heart failure (P = 0.04), emergency surgery (P = 0.02), general anesthesia (P = 0.03), preoperative history of coronary artery disease (P = 0.001), preoperative treatment with beta-blockers (P = 0.003), lower preoperative (P = 0.03) and postoperative (P = 0.002) hemoglobin concentrations, increased bleeding rate (as assessed from increased cell salvage; P = 0.025), and lower ejection fraction (P = 0.02). Of the 107 patients with PMI, 20.6% died of cardiac cause during the same hospital stay. The following factors increased the odds ratios for cardiac death: age (P = 0.001), recent congestive heart failure (P = 0.01), type of surgery (P = 0.04), emergency surgery (P = 0.02), lower intraoperative diastolic blood pressure (P = 0.001), new intraoperative ST-T changes (P = 0.01), and increased intraoperative use of blood (P = 0.005). Patients who underwent coronary artery bypass grafting, even more than 12 months before index surgery, had a 79% reduction in risk of death if they had PMI (P = 0.01). Multivariable analysis revealed preoperative definitive diagnosis of coronary artery disease (P = 0.001) and significant valvular disease (P = 0.03) were associated with increased risk of PMI. Congestive heart failure less than 1 yr before index vascular surgery (P = 0. 0002) and increased intraoperative use of blood (P = 0.007) were associated with cardiac death. The history of coronary artery bypass grafting reduced the risk of cardiac death (P = 0.04) in patients with PMI. CONCLUSIONS: The in-hospital cardiac mortality rate is high for patients who undergo vascular surgery and experience clinically significant PMI. Stress of surgery (increased intraoperative bleeding and aortic, peripheral vascular, and emergency surgery), poor preoperative cardiac functional status (congestive heart failure, lower ejection fraction, diagnosis of coronary artery disease), and preoperative history of coronary artery bypass grafting are the factors that determine perioperative cardiac morbidity and mortality rates.

Anesthetic aspects of laparoscopic and open adrenalectomy for pheochromocytoma.

OBJECTIVES: To compare the anesthetic aspects and intraoperative hemodynamic data and immediate postoperative outcomes in patients whose pheochromocytoma resection was performed either laparoscopically or by traditional open surgery. METHODS: Fourteen consecutive patients who underwent laparoscopic procedures (a single surgeon) were compared with 20 patients who underwent open surgery. The patients' records were reviewed for demographic information, preoperative medical history and therapy, intraoperative hemodynamic data, fluid balance, and immediate postoperative course. RESULTS: No differences between the highest intraoperative blood pressures and number of hypertensive episodes between the two groups were found. However, in laparoscopic patients, the intraoperative hypotension was less severe (mean lowest blood pressure 98/57 mm Hg versus 88/50 mm Hg, P = 0.05), and the hypotensive episodes were less frequent (median 0 versus 2, P = 0.005) and required fewer interventions with vasopressors (P = 0.02). Extreme high and extreme low heart rates did not differ between the two groups. The estimated blood loss was lower in the laparoscopic group (P = 0.0001), but the total intraoperative fluid requirement and operative times were similar in the two groups. Patients in the laparoscopic group resumed walking earlier (median 1.5 versus 4 days, P = 0.002) and resumed oral food intake sooner (median 1 versus 3.5 days, P = 0.0001). The median duration of hospitalization in patients who underwent laparoscopic and open adrenalectomy was 3 and 7.5 days, respectively (P = 0.001). CONCLUSIONS: Intraoperative hemodynamic values during laparoscopic adrenalectomy for pheochromocytoma were comparable to those of traditional open surgery, but the patients who underwent the laparoscopic procedure had a faster postoperative recovery.