The effect of adjusting tracheal tube cuff pressure during deep hypothermic circulatory arrest: a randomised trial.

BACKGROUND: Regular endotracheal tube cuff monitoring may prevent silent aspiration. OBJECTIVES: We hypothesised that active management of the cuff of the tracheal tube during deep hypothermic cardiac arrest would reduce silent subglottic aspiration. We also determined to study its effect on postoperative mechanical ventilation and the incidence of postoperative positive tracheal cultures. DESIGN: A randomised clinical trial. SETTING: The study was conducted in a University Teaching Hospital from September 2008 to November 2009. PATIENTS: Twenty-four patients undergoing elective pulmonary endarterectomy were included in the study. INTERVENTION: After induction of general anaesthesia and tracheal intubation, the cuff of the tracheal tube was inflated to 25 cmH2O. Following this, 1 ml of methylene blue dye diluted in 2 ml of physiological saline was injected into the hypopharynx. Patients were randomly assigned to active cuff management during cooling and warming (where cuff pressure was monitored and the cuff was reinflated if it dropped below 20 cmH2O, or deflated if pressure exceeded 30 cmH2O) or passive monitoring (where cuff pressure was monitored but volume was not altered). Before weaning from cardiopulmonary bypass, fibreoptic bronchoscopy was performed. Silent aspiration was then diagnosed if blue dye was seen in the trachea below the cuff of the tube. MAIN OUTCOME MEASURES: The primary aim of this study was to determine the incidence of silent aspiration. Secondary outcomes included duration of postoperative mechanical ventilation of the lungs and incidence of positive culture of tracheal aspirate. RESULTS: Active cuff management patients were younger than controls (51.2 ±â€Š11.6 vs. 63.2 ±â€Š9 years, P = 0.028), but otherwise the two groups were similar. The primary endpoint was reached because we showed that silent aspiration was significantly less frequent in the study group (0/12 vs. 8/12 patients, P = 0.001). Significantly lower intracuff pressures were measured in the control group patients at several timepoints during cooling, just before hypothermic arrest and at all timepoints during rewarming. CONCLUSION: We recommend that the cuff of the tracheal tube should be checked regularly during surgery under deep hypothermia, and the cuff pressure adjusted as required.

Bio-based unsaturated polyester resin from post-consumer PET.

This study explores the utilization of post-consumer poly(ethylene terephthalate) (PET) as a material in the synthesis of styrene-free unsaturated polyester (UP) resin. The process involves glycolysis of PET waste with diethylene glycol and condensation polymerization with bio-based itaconic acid. The resulting unsaturated polyester possesses reactive methylidene functions that, in contrast to commonly employed fumarates/maleates, facilitate copolymerization with non-styrene reactive diluents. To formulate the resins, methacrylates and itaconates were used for dilution, and the curing process is achieved through a redox initiation system at room temperature, followed by post-curing at elevated temperatures. The cured formulations were characterized by their glass transition temperature, determined by DMA analysis. Mechanical properties were evaluated using standardized tests in tension, flexure, and compression. Particularly promising characteristics are observed in formulations incorporating bio-based dimethyl itaconate (DMI), allowing the formulation of materials with a high ultimate flexural strength (σf,max = 161.4 MPa) and compressive yield point (σc,yield = 131.3 MPa). Furthermore, the low volatility of DMI addresses the health, safety, and ecological concerns associated with the commonly used styrene. This technology not only presents a promising avenue for sustainable UP resin for glass fiber reinforced composites but also allows upcycling PET waste.

Does preoperative B-type natriuretic peptide better predict adverse outcome and prolonged length of stay than the standard European System for Cardiac Operative Risk Evaluation after cardiac surgery?

OBJECTIVES: Although B-type natriuretic peptide (BNP) strongly predicts cardiac morbidity and mortality, the European System for Cardiac Operative Risk Evaluation (EuroSCORE) has a modest predictive value to identify a composite operative risk after cardiac surgery. The authors tested the hypothesis that a single preoperative BNP measurement would be superior to standard EuroSCORE in predicting composite adverse outcomes after cardiac surgery. DESIGN: A prospective observational study. SETTING: A teaching university hospital. PARTICIPANTS: Two hundred eight adult patients. INTERVENTIONS: Conventional cardiac surgery with cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: The preoperative additive EuroSCORE and BNP measurement were performed in all patients. Postoperative nonfatal major adverse cardiac events (malignant ventricular arrhythmia, myocardial infarction, and cardiac dysfunction), all-cause mortality, and prolonged lengths of stay were chosen as study endpoints. Predictive abilities of both EuroSCORE and BNP were assessed using logistic regression and compared with receiver operating characteristic (ROC) curves. Thirty-six (17%, 95% confidence interval [CI], 12%-22%) patients experienced 49 events over the study period. The areas under the ROC curves assessing the utility of EuroSCORE and BNP in predicting adverse outcome and prolonged in-hospital stay were 0.59 (95% CI, 0.48-0.69) versus 0.76 (95% CI, 0.68-0.85; p < 0.001) and 0.65 (95% CI, 0.57-0.74) versus 0.71 (95% CI, 0.63-0.80; p = 0.147), respectively. Using logistic regression, BNP considered as a dichotomized variable was the only independent predictor of adverse cardiac outcome (adjusted odds ratio = 10.7; 95% CI, 4.1-27.8; p < 0.001). CONCLUSIONS: Preoperative BNP measurement is a strong, independent, and more accurate predictor of adverse outcome than EuroSCORE in patients undergoing cardiac surgery. BNP could be considered as a simple and objective tool for the detection of high-risk patients after cardiac surgery.

Use of high-thoracic epidural analgesia in pulmonary endarterectomy: a randomized feasibility study.

BACKGROUND: The suitability of combined high-thoracic epidural anesthesia for pulmonary endarterectomy was studied. METHODS: A prospective randomized clinical study was conducted in a university medical center from November 2005 to December 2006. The primary endpoint of this study was to evaluate perioperative hemodynamic data; secondary endpoints were to evaluate the duration of artificial ventilation, length of stay in the intensive care unit, and the impact on postoperative morbidity and mortality. RESULTS: The 16 patients in the study group received high-thoracic epidural anesthesia plus general anesthesia; the 16 control patients received total intravenous anesthesia alone. Hemodynamic parameters and drug use, as well as the time to extubation, rate of complications, postoperative pain, the length of intensive care unit stay, and mortality, were recorded. The 2 groups were comparable with respect to hemodynamic stability during induction of anesthesia. The study group patients had significantly lower sufentanil consumption (mean +/- SD, 2.1 +/- 0.7 microg/kg versus 9.1 +/- 3.1 microg/kg; P <.001), a shorter period of artificial ventilation (34 +/- 35 hours versus 52 +/- 49 hours; P = .0318), and lower postoperative pain scores at 3 hours (0.10 +/- 0.26 versus 0.93 +/- 1.38; P = .015), 12 hours (0.14 +/- 0.53 versus 0.93 +/- 0.79; P = .002), and 24 hours (0.35 +/- 0.49 versus 1.33 +/- 1.04; P = .007). CONCLUSIONS: This study has shown that combined epidural and general anesthesia is a suitable anesthetic option in patients who are selected for pulmonary endarterectomy. It provides hemodynamic stability and reduces the duration of tracheal intubation postoperatively and improves postoperative pain relief, although this option has not been shown to decrease either the length of the intensive care unit stay or mortality.

Comparison of three protocols for tight glycemic control in cardiac surgery patients.

OBJECTIVE: We performed a randomized trial to compare three insulin-titration protocols for tight glycemic control (TGC) in a surgical intensive care unit: an absolute glucose (Matias) protocol, a relative glucose change (Bath) protocol, and an enhanced model predictive control (eMPC) algorithm. RESEARCH DESIGN AND METHODS: A total of 120 consecutive patients after cardiac surgery were randomly assigned to the three protocols with a target glycemia range from 4.4 to 6.1 mmol/l. Intravenous insulin was administered continuously or in combination with insulin boluses (Matias protocol). Blood glucose was measured in 1- to 4-h intervals as requested by the protocols. RESULTS: The eMPC algorithm gave the best performance as assessed by time to target (8.8 +/- 2.2 vs. 10.9 +/- 1.0 vs. 12.3 +/- 1.9 h; eMPC vs. Matias vs. Bath, respectively; P < 0.05), average blood glucose after reaching the target (5.2 +/- 0.1 vs. 6.2 +/- 0.1 vs. 5.8 +/- 0.1 mmol/l; P < 0.01), time in target (62.8 +/- 4.4 vs. 48.4 +/- 3.28 vs. 55.5 +/- 3.2%; P < 0.05), time in hyperglycemia >8.3 mmol/l (1.3 +/- 1.2 vs. 12.8 +/- 2.2 vs. 6.5 +/- 2.0%; P < 0.05), and sampling interval (2.3 +/- 0.1 vs. 2.1 +/- 0.1 vs. 1.8 +/- 0.1 h; P < 0.05). However, time in hypoglycemia risk range (2.9-4.3 mmol/l) in the eMPC group was the longest (22.2 +/- 1.9 vs. 10.9 +/- 1.5 vs. 13.1 +/- 1.6; P < 0.05). No severe hypoglycemic episode (<2.3 mmol/l) occurred in the eMPC group compared with one in the Matias group and two in the Bath group. CONCLUSIONS: The eMPC algorithm provided the best TGC without increasing the risk of severe hypoglycemia while requiring the fewest glucose measurements. Overall, all protocols were safe and effective in the maintenance of TGC in cardiac surgery patients.