Perioperative blood transfusions in hip and knee arthroplasty: a retrospective assessment of combined risk factors.

INTRODUCTION: Accurate identification of patients at risk of blood transfusion can reduce complications and improve institutional resource allocation. Probabilistic models are used to detect risk factors and formulate patient blood management strategies. Whether these predictors vary among institutions is unclear. We aimed to identify risk factors among our patients who underwent total hip (THA) or knee (TKA) arthroplasty, and combine these predictors to improve our model. MATERIALS AND METHODS: We retrospectively assessed risk factors among 531 adults who underwent elective THA or TKA from January 2016 to November 2018. Using relevant surgical and patient characteristics gathered from electronic medical records, we conducted univariable and multivariable analyses. For our logistic regression model, we measured the impact of independent variables (age, gender, operation type (THA or TKA) and preoperative hemoglobin concentration) on the need for a transfusion. RESULTS: Of the 531 patients, 321 had THA (uncemented) and 210 had TKA. For the selected period, our transfusion rate of 8.1% (10.6% THA and 4.3% TKA) was low. Univariable analyses showed that lower BMI (p < 0.001) was associated with receiving a transfusion. Important factors identified through logistic regression analyses were age (estimated effect of an interquartile range increase in age: OR 3.89 [CI 95% 1.96-7.69]), TKA (OR - 0.77 [CI 95% - 1.57-0.02]), and preoperative hemoglobin levels (estimated effect of interquartile range increase in hemoglobin: OR 0.47 [CI 95% 0.31-0.71]). Contrary to findings from previous reports, gender was not associated with transfusion. CONCLUSIONS: Previously published predictors such as advanced age, low preoperative hemoglobin, and procedure type (THA) were also identified in our analysis. However, gender was not a predictor, and BMI showed the potential to influence risk. We conclude that, when feasible, the determination of site-specific transfusion rates and combined risk factors can assist practitioners to customize care according to the needs of their patient population. LEVEL OF EVIDENCE: Level 3, retrospective cohort study.

Placement of TOF-Cuff® on the lower leg for neuromuscular and blood pressure monitoring during anesthetic induction for shoulder surgeries.

PURPOSE: The aim of this study was to compare two devices for neuromuscular monitoring during anesthetic induction. TOF-Cuff® was installed on the lower leg stimulating the tibial nerve, while the more conventional TOF-Scan® was installed over the ulnar nerve at the wrist. Methods Twenty adult patients were enrolled in this prospective, controlled study. Train-of-four (TOF) was recorded every 15 s until TOF ratio of 0%. Mean arterial blood pressure (MAP) was assessed with TOF-Cuff® and with standard anesthesia monitoring from the brachial artery. MAP was measured before and after anesthetic induction. Time to TOF ratio = 0% was compared with one-sample t test and Bland-Altman plots. Results Patients received 0.53 ± 0.09 mg atracurium per kg body weight intravenously. Mean time to TOF ratio = 0% was 150.8 s (± 43.7) for TOF-Scan®, and 174.4 s (± 42.7) for TOF-Cuff® (p = 0.1356). Bias was - 15.9 (95% confidence interval - 37.5 to 5.6) with 95% limits of agreement of - 95.2 to 63.3. Twenty-five percent of the patients had a technical issue with a TOF-Cuff® measurement. For MAP, mean difference was 1.4 (95% confidence interval - 2.4 to 5.2) with 95% limits of agreement of - 22.7 to 25.5. Conclusion The time from administration of a common dose of atracurium to a TOF ratio of 0% assessed with TOF-Cuff® stimulating the tibial nerve compared to TOF-Scan® stimulating the ulnar nerve showed large limits of agreement in Bland-Altman analysis. There was a high failure rate with TOF-Cuff® measurements on the lower leg.

Viscoelastic Monitoring to Guide the Correction of Perioperative Coagulopathy and Massive Transfusion in Patients with Life-Threatening Hemorrhage.

The resuscitation of patients with traumatic hemorrhage remains a challenging clinical scenario. The appropriate and aggressive support of the patient's coagulation is of critical importance. Conventional coagulation assays present several shortcomings in this setting. The integration of viscoelastic monitoring in clinical practice has the potential to result in significant improvements. In order to be successful, the provider must understand basics of the methodology, read outs, and the limitations of the technique.

Dimensional Variations of Left-Sided Double-Lumen Endobronchial Tubes.

BACKGROUND: Tube size selection is critical in ventilating patients' lungs using double-lumen endobronchial tubes (DLTs). Little information about relevant parameters is readily available from manufacturers. The aim of this study is to provide reference data for relevant dimensions of conventionally available DLTs. METHODS: In this study in a benchmark in vitro setup, several dimensional parameters of four sizes of left-sided double-lumen endobronchial tubes from six different manufacturers were assessed, such as distances and diameters of tube shaft, cuff lengths, and diameters as well the angle at the tip. RESULTS: Endobronchial tubes of ostensibly the same size revealed wide variation in measured parameters between brands from different manufacturers. In some parameters, there was an overlap between different sizes from the same manufacturer, i.e., diameters and distances did not increase with increasing nominal endobronchial tube size. The information about dimensions of endobronchial tubes provided by manufacturers' leaflets is insufficient. CONCLUSIONS: Endobronchial tube size selection carries unnecessary uncertainty because clinically relevant parameters are unknown and vary considerably between different manufacturers.

Endotracheal tube cuff pressure changes during manual cuff pressure control manoeuvres: An in-vitro assessment.

BACKGROUND: Endotracheal tube (ETT) cuffs are designed to seal the lower airway for precise ventilation and to protect against ingress of pathogens from the pharyngeal space. Therefore, a minimal continuous cuff pressure must be maintained. Aim of this study was to analyse the course of cuff pressure in an in-vitro model during manual cuff pressure control manoeuvres. METHODS: An artificial trachea was intubated with an appropriately sized ETT and cuff pressure set to 20 cm H2 O. Thirty-two experienced ICU nurses each performed six cuff pressure control manoeuvres (three times in two different ETTs) using a manual cuff pressure manometer. Course of cuff pressure from connecting the manometer to disconnecting it from the cuff pilot balloon was recorded using a pressure transducer. RESULTS: There were 190 cuff pressure control manoeuvres suitable for analysis. In all control manoeuvres a cuff pressure below 20 cm H2 O was noted. In 20.0% of the control manoeuvres the cuff pressure dropped below 10 cm H2 O. Cuff pressure drops were mainly caused by initially connecting the manometer to the pilot balloon, less frequently by manipulating the pressure gauge of the manometer. Disconnecting the manometer after the control manoeuvre caused a cuff pressure drop in 78.1% of cases, contributing to a final cuff pressure below 20 cm H2 O in 31.3% of control manoeuvres. CONCLUSION: Routine manual cuff pressure control manoeuvres in ETT cuffs result in considerable cuff pressure drops. This may have an impact on silent aspiration of pharyngeal contents passing along the cuff into the lower airway.

Anesthetic management of patients undergoing bariatric surgery: two year experience in a single institution in Switzerland.

BACKGROUND: In the field of anesthesia for bariatric surgery, a wide variety of recommendations exist, but a general consensus on the perioperative management of such patients is missing. We outline the perioperative experiences that we gained in the first two years after introducing a bariatric program. METHODS: The perioperative approach was established together with all relevant disciplines. Pertinent topics for the anesthesiologists were; successful airway management, indications for more invasive monitoring, and the planning of the postoperative period and deposition. This retrospective analysis was approved by the local ethics committee. Data are mean [SD]. RESULTS: 182 bariatric surgical procedures were performed (147 gastric bypass procedures (GBP; 146 (99.3%) performed laparascopically). GBP patients were 43 [10] years old, 78% female, BMI 45 [7] kg/m(2), 73% ASA physical status of 2. 42 patients (28.6%) presented with obstructive sleep apnea syndrome. 117 GBP (79.6%) patients were intubated conventionally by direct laryngoscopy (one converted to fiber-optic intubation, one aspiration of gastric contents). 32 patients (21.8%) required an arterial line, 10 patients (6.8%) a central venous line. Induction lasted 25 [16] min, the procedure itself 138 [42] min. No blood products were required. Two patients (1.4%) presented with hypothermia (<35 °C) at the end of their case. The emergence period lasted 17 [9] min. Postoperatively, 32 patients (21.8%) were transferred to the ICU (one ventilated). The other patients spent 4.1 [0.7] h in the post anesthesia care unit. 15 patients (10.2%) required take backs for surgical revision (two laparotomies). CONCLUSIONS: The physiology and anatomy of bariatric patients demand a tailored approach from both the anesthesiologist and the perioperative team. The interaction of a multi-disciplinary team is key to achieving good outcomes and a low rate of complications. TRIAL REGISTRATION: DRKS00005437 (date of registration 16(th) December 2013).

Late pharmacologic conditioning with volatile anesthetics after cardiac surgery.

INTRODUCTION: The aim of this randomized controlled trial was to investigate whether volatile anesthetics used for postoperative sedation have any beneficial effects on myocardial injury in cardiac surgery patients after on-pump valve replacement. METHODS: Anesthesia was performed with propofol. After arrival in the intensive care unit (ICU), 117 patients were randomized to be sedated for at least 4 hours with either propofol or sevoflurane. Sevoflurane was administered by using the anesthetic-conserving device. Troponin T, creatine kinase, creatine kinase from heart muscle tissue, myoglobin, and oxygenation index were determined on arrival at the ICU, 4 hours after sedation, and in the morning of the first postoperative day (POD1). Primary end points were cardiac injury markers on POD1. As secondary end points oxygenation, postoperative pulmonary complications, and ICU and hospital stay were documented. RESULTS: Fifty-six patients were analyzed in the propofol arm, and 46 patients in the sevoflurane arm. Treatment groups were comparable with regard to patient demographics and intraoperative characteristics. Concentration of troponin T as the most sensitive marker for myocardial injury at POD1 was significantly lower in the sevoflurane group compared with the propofol group (unadjusted difference, -0.4; 95% CI, -0.7 to -0.1; P < 0.01; adjusted difference, -0.2; 95% CI, -0.4 to -0.02; P = 0.03, respectively). CONCLUSIONS: The data presented in this investigation indicate that late postconditioning with the volatile anesthetic sevoflurane might mediate cardiac protection, even with a late, brief, and low-dose application. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00924222.

Anesthetic-induced improvement of the inflammatory response to one-lung ventilation.

BACKGROUND: Although one-lung ventilation (OLV) has become an established procedure during thoracic surgery, sparse data exist about inflammatory alterations in the deflated, reventilated lung. The aim of this study was to prospectively investigate the effect of OLV on the pulmonary inflammatory response and to assess possible immunomodulatory effects of the anesthetics propofol and sevoflurane. METHODS: Fifty-four adults undergoing thoracic surgery with OLV were randomly assigned to receive either anesthesia with intravenously applied propofol or the volatile anesthetic sevoflurane. A bronchoalveolar lavage was performed before and after OLV on the lung side undergoing surgery. Inflammatory mediators (tumor necrosis factor alpha, interleukin 1beta, interleukin 6, interleukin 8, monocyte chemoattractant protein 1) and cells were analyzed in lavage fluid as the primary endpoint. The clinical outcome determined by postoperative adverse events was assessed as the secondary endpoint. RESULTS: The increase of inflammatory mediators on OLV was significantly less pronounced in the sevoflurane group. No difference in neutrophil recruitment was found between the groups. A positive correlation between neutrophils and mediators was demonstrated in the propofol group, whereas this correlation was missing in the sevoflurane group. The number of composite adverse events was significantly lower in the sevoflurane group. CONCLUSIONS: This prospective, randomized clinical study suggests an immunomodulatory role for the volatile anesthetic sevoflurane in patients undergoing OLV for thoracic surgery with significant reduction of inflammatory mediators and a significantly better clinical outcome (defined by postoperative adverse events) during sevoflurane anesthesia.