Markus Klimek

Trends but Not Individual Values of Central Venous Oxygen Saturation Agree with Mixed Venous Oxygen Saturation during Varying Hemodynamic Conditions

Background:Previous studies found contradictory results regarding the question whether mixed venous oxygen saturation (Svo2) and central venous oxygen saturation (Scvo2) are equivalent. The inconsistency of study results may result from different study designs and different, partly questionable, statistical approaches. Methods:The authors performed a prospective clinical trial comparing individual oxygen saturation values as well as the trend of values in blood from the superior vena cava (Scvo2), the right atrium (Srao2), and the pulmonary artery (Svo2) during varying hemodynamic situations. The subjects were 70 patients scheduled to undergo elective neurosurgical operations in the sitting position. Oxygen saturation was measured photospectrometrically in blood samples simultaneously taken at four different time points during supine and sitting positions. Statistical analysis was performed following the recommendations of Bland and Altman. Results:Five hundred two comparative sets of measurements were obtained. Ninety-five percent limits of agreement ranging from ±6.83 to ±9.30% for single values were interpreted as clinically unacceptable. In contrast, correlations between changes of Svo2 and Scvo2 as well as of Svo2 and Srao2 were interpreted as clinically acceptable (R ≥ 0.755, Pearson correlation coefficient; P ≤ 0.0001). Conclusions:In this sample of patients, exact numerical values of Scvo2 and Srao2 are not equivalent to those of Svo2 in varying hemodynamic conditions. However, for clinical purposes, the trend of Scvo2 may be substituted for the trend of Svo2. In addition, previous studies investigating the agreement between Svo2 and Scvo2 were found to be lacking in their chosen statistical approaches.

Reversal of rocuronium-induced (1.2 mg/kg) profound neuromuscular block by sugammadex: a multicenter, dose-finding and safety study.

Background: Reversal of rocuronium-induced neuromuscular blockade can be accomplished by chemical encapsulation of rocuronium by sugammadex, a modified &ggr;-cyclodextrin derivative. This study investigated the efficacy and safety of sugammadex in reversing rocuronium-induced profound neuromuscular blockade at 5 min in American Society of Anesthesiologists physical status I and II patients. Methods: Forty-five American Society of Anesthesiologists physical status I and II patients (aged 18–64 yr) scheduled to undergo surgical procedures (anticipated anesthesia duration ≥ 90 min) were randomly assigned to a phase II, multicenter, assessor-blinded, placebo-controlled, parallel, dose-finding study. Anesthesia was induced and maintained with propofol and an opioid. Profound neuromuscular blockade was induced with 1.2 mg/kg rocuronium bromide. Sugammadex (2.0, 4.0, 8.0, 12.0, or 16.0 mg/kg) or placebo (0.9% saline) was then administered 5 min after the administration of rocuronium. Neuromuscular function was monitored by acceleromyography, using train-of-four nerve stimulation. Recovery time was the time from the start of administration of sugammadex or placebo, to recovery of the train-of-four ratio to 0.9. Safety assessments were performed on the day of the operation and during the postoperative and follow-up period. Results: A total of 43 patients received either sugammadex or placebo. Increasing doses of sugammadex reduced the mean recovery time from 122 min (spontaneous recovery) to less than 2 min in a dose-dependent manner. Signs of recurrence of blockade were not observed. No serious adverse events related to sugammadex were reported. Two adverse events possibly related to sugammadex were reported in two patients (diarrhea and light anesthesia); however, both patients recovered without sequelae. Conclusions: Sugammadex rapidly and effectively reversed profound rocuronium-induced neuromuscular blockade in humans and was well tolerated.

Postoperative Analgesia with No Motor Block by Continuous Epidural Infusion of Ropivacaine 0.1% and Sufentanil After Total Hip Replacement

UNLABELLED We assessed the analgesic efficacy of postoperative epidural ropivacaine 0.1% with and without sufentanil 1 microgram/mL in this prospective, randomized, single-blinded study of 30 ASA physical status I-III patients undergoing elective total hip replacement. Lumbar epidural block using 0.75% ropivacaine was combined with either propofol sedation or general anesthesia for surgery. After surgery, the epidural infusion was commenced. Fifteen patients in each group received either an epidural infusion of 0.1% ropivacaine with 1 microgram/mL sufentanil (R + S) or 0.1% ropivacaine without sufentanil (R) at a rate of 5-9 mL/h. All patients had access to i.v. piritramide via a patient-controlled analgesia device. The R + S group consumed six times less piritramide over a 48-h infusion period than the R group (median 12.7 vs 73.0 mg; P < 0.001). Motor block was negligible for the study duration in both groups. Patient satisfaction was excellent. The incidence of adverse events, such as nausea, was similar. We conclude that a continuous epidural infusion of 0.1% ropivacaine with 1 microgram/mL sufentanil is more effective than ropivacaine alone in treating pain after elective hip replacement without motor block. IMPLICATIONS This is the first randomized study comparing the efficacy of the epidural combination of ropivacaine 0.1% and sufentanil 1 microgram/mL versus plain ropivacaine 0.1% in treating pain after hip replacement. We found that ropivacaine 0.1% and sufentanil 1 microgram/mL led to a sixfold reduction in opioid requirements after total hip replacement by producing a negligible motor block.

A Simulation Model for Determining the Optimal Size of Emergency Teams on Call in the Operating Room at Night

BACKGROUND: Hospitals that perform emergency surgery during the night (e.g., from 11:00 pm to 7:30 am) face decisions on optimal operating room (OR) staffing. Emergency patients need to be operated on within a predefined safety window to decrease morbidity and improve their chances of full recovery. We developed a process to determine the optimal OR team composition during the night, such that staffing costs are minimized, while providing adequate resources to start surgery within the safety interval. METHODS: A discrete event simulation in combination with modeling of safety intervals was applied. Emergency surgery was allowed to be postponed safely. The model was tested using data from the main OR of Erasmus University Medical Center (Erasmus MC). Two outcome measures were calculated: violation of safety intervals and frequency with which OR and anesthesia nurses were called in from home. We used the following input data from Erasmus MC to estimate distributions of all relevant parameters in our model: arrival times of emergency patients, durations of surgical cases, length of stay in the postanesthesia care unit, and transportation times. In addition, surgeons and OR staff of Erasmus MC specified safety intervals. RESULTS: Reducing in-house team members from 9 to 5 increased the fraction of patients treated too late by 2.5% as compared to the baseline scenario. Substantially more OR and anesthesia nurses were called in from home when needed. CONCLUSION: The use of safety intervals benefits OR management during nights. Modeling of safety intervals substantially influences the number of emergency patients treated on time. Our case study showed that by modeling safety intervals and applying computer simulation, an OR can reduce its staff on call without jeopardizing patient safety.

Defining the learning curve for endotracheal intubation using direct laryngoscopy: A systematic review

More than two failed intubation attempts and failed endotracheal intubations (ETIs) are associated with severe complications and death. The aim of this review was to determine the number of ETIs a health care provider in training needs to perform to achieve proficiency within two attempts. A systematic search of the literature was conducted covering the time frame of January 1990 through July 2014. We identified 13 studies with a total of 1462 students who had attempted to intubate 19,108 patients. This review shows that in mostly elective circumstances, at least 50 ETIs with no more than two intubation attempts need to be performed to reach a success rate of at least 90%. However, the evidence is heterogeneous, and the incidence of difficult airways in non-elective settings is up to 20 times higher compared to elective settings. Taking this factor into account, training should include a variety of exposures and should probably exceed 50 ETIs to successfully serve the most vulnerable patients.

Train-of-four ratio recovery often precedes twitch recovery when neuromuscular block is reversed by sugammadex

Background: Sugammadex reverses rocuronium‐induced neuromuscular block (NMB). In all published studies investigating sugammadex, the primary outcome parameter was a train‐of‐four (TOF) ratio of 0.9. The recovery time of T1 was not described. This retrospective investigation describes the recovery of T1 vs. TOF ratio after the reversal of NMB with sugammadex.

Perioperative fluid management and use of vasoactive and antithrombotic agents in free flap surgery: a literature review and clinical recommendations.

LEARNING OBJECTIVES After reading this article, the participant should be able to (1) outline the rationale for different perioperative types of fluid therapy in free flap surgery and identify the methods considered best for flap survival; (2) understand the current views on the use of vasoactive agents and consider its possible safe use; (3) compare the most commonly used intraoperative and postoperative anticoagulant therapies and identify the risks and benefits associated with each. BACKGROUND Free flap surgery has become a reliable and efficient method for reconstruction of complex soft tissue and bony defects. Despite high success rates, free flap failure remains an important concern. A review of the literature was conducted on nonsurgical factors that may contribute to flap failure or success. Various anesthesiological and anticoagulant methods are applied in free flap surgery, but for the ideal approach there is no consensus. This article provides clinical recommendations on perioperative fluid management and the use of vasoactive and antithrombotic agents and offers a balanced view on the risks and benefits.

The influence of various anesthetics on the release and metabolism of thyroid hormones : results of two clinical studies

Normal functioning of the thyroid gland during surgery is important, but few data are available on the possible interactions between anesthesia and thyroid hormones.In two independent studies we examined the influence of different types of general anesthesia on the plasma levels of the thyroid hormones. They revealed an intraoperative increase of free thyroxine (fT4) and total thyroxine (tT4) in plasma to approximately 150% of preanesthesia levels when enflurane was used. No increase in thyroid-stimulating hormone (TSH) secretion was noted prior to this. The increase was not due to a quantitative change in the binding proteins. The plasma levels of fT4 and tT4 returned to normal postoperatively; however, no accompanying increase in plasma triiodothyronine levels was observed. Hence we assume the increase to be due to hormone release from thyroid and/or extrathyroidal stores--an intercompartmental shifting. (Anesth Analg 1995;81:612-8)

Paravertebral block and persistent postoperative pain after breast surgery: meta-analysis and trial sequential analysis.

We examined whether paravertebral block has an effect on the prevalence of persistent postsurgical pain after breast surgery. Seven randomised, controlled trials (559 patients) which had the outcome assessor blinded were included, comparing patients who received paravertebral blocks after breast surgery with patients who did not. The risk ratio (95% CI) was 0.75 (0.48–1.15) for the incidence of postoperative pain at 3 months (four studies, 317 patients); the risk ratio (95% CI) obtained from three studies including 301 patients reporting on pain after 6 months was 0.57 (0.29–1.72), and the risk ratio (95% CI) for pain after 12 months (three trials, 237 patients) was 0.42 (0.15–1.23). Conventional meta‐analysis using the random effects model thus showed no statistically significant risk reduction for persistent postoperative pain at 3 months, 6 months or 12 months. Trial sequential analysis, used to consider the risk of type 1 and type 2 random error, showed that at 3 months, 6 months and 12 months, the number of subjects in the analyses were only 18.3%, 6.8% and 4.2% of the required information sizes at those time points, respectively. Our study is the first to evaluate data on pain 12 months postoperatively. Trial sequential analysis revealed that the current evidence is not sufficient to reach a conclusion. These findings stand in contrast to previous meta‐analyses with fewer studies that had concluded that paravertebral block effectively reduces chronic pain.

General Anaesthesia is Associated with Adverse Cardiac Outcome after Endovascular Aneurysm Repair

OBJECTIVES Endovascular aneurysm repair (EVAR) is associated with reduced cardiac stress compared with open repair and is an attractive therapeutic option, especially in cardiac fragile patients. General and locoregional anaesthesia differ regarding the stress response evoked by surgery. The aim of the study is to compare the incidence of cardiac events after EVAR under general or locoregional anaesthesia. METHODS A total of 302 consecutive patients undergoing infrarenal EVAR between 2002 and 2011 were analysed in this retrospective cohort study. Selection of anaesthesia type was at the discretion of the treating physicians. Medical history, medication use, anaesthesia technique and follow-up were obtained. The study end point was 30-day cardiac complications, including cardiac death, non-fatal myocardial infarction, heart failure, ventricular arrhythmia and troponin T release. Multivariable analysis, adjusted for the propensity of receiving a locoregional technique and cardiac risk factors according to the Revised Cardiac Risk Index, was used to assess the association between cardiac events and anaesthesia type. RESULTS A total of 173 patients underwent general anaesthesia and 129 locoregional anaesthesia. Obesity, aspirin use and therapeutic anticoagulation were more common in patients receiving general anaesthesia. Cardiac events were observed in 13.3% of patients receiving general anaesthesia and in 4.7% of patients receiving locoregional anaesthesia (P = 0.02), or 6.4% versus .8% (P = 0.02) when asymptomatic troponin release is excluded from the end point. In the general anaesthesia group, two cardiac deaths, six non-fatal myocardial infarctions, two cases of non-fatal heart failure, one non-fatal cardiac arrest and 12 cases of troponin T release were observed, compared with one myocardial infarction and five cases of troponin T release in the locoregional anaesthesia group. In multivariable analysis, general anaesthesia was associated with adverse cardiac events (odds ratio (OR) 3.8; 95%-confidence interval (CI) 1.1-12.9). Non-cardiac complications occurred in 11.6% of patients in both groups (P = 1.00). CONCLUSION General anaesthesia was associated with an increased risk of cardiac events in EVAR, compared with locoregional anaesthesia.