Warning criteria for MEP monitoring during carotid endarterectomy: a retrospective study of 571 patients.

Monitoring of transcranial electrical motor evoked potentials (tcMEP) during carotid endarterectomy (CEA) has been shown to effectively detect intraoperative cerebral ischemia. The unique purpose of this study was to evaluate changes of MEP amplitude (AMP), area under the curve (AUC) and signal morphology (MOR) as additional MEP warning criteria for clamping-associated ischemia during CEA. Therefore, the primary outcome was the number of MEP alerts (AMP, AUC and MOR) in the patients without postoperative motor deficit (false positives). We retrospectively reviewed data from 571 patients who received CEA under general anesthesia. Monitoring of somatosensory evoked potentials (SSEP) and tcMEP was performed in all cases (all-or-none MEP warning criteria). The percentages of false positives (primary parameter) of AMP, AUC and MOR were evaluated according to the postoperative motor outcome. In the cohort of 562 patients, we found significant SSEP/MEP changes in 56 patients (9.96%). In 44 cases (7.83%) a shunt was inserted. Nine patients (1.57%) were excluded due to MEP recording failure. False positives were registered for AMP, AUC and MOR changes in 121 (24.01%), 148 (29.36%) and 165 (32.74%) patients, respectively. In combination of AMP/AUC and AMP/AUC/MOR false positives were found in 9.52% and 9.33% of the patients. This study is the first to evaluate the correctness of the MEP warning criteria AMP, AUC and MOR with regard to false positive monitoring results in the context of CEA. All additional MEP warning criteria investigated produced an unacceptably high number of false positives and therefore may not be useful in carotid surgery for adequate detection of clamping-associated ischemia.

A 'metabolic bundle' including Oxandrolone in optimising the metabolic status of severely burn injured patients: a retrospective analysis of the first 50 patients.

Objective: Severe burn injuries are associated with a rapid escalating hypermetabolic state and catabolism of muscle mass. To ameliorate this process a standardized approach using pharmacological and non-pharmacological interventions was implemented within a single burns center. Whilst individual components of this standardized package are well documented in the literature, their collective or bundled effect has not as yet been assessed. The aim of this study was to evaluate the efficacy of this standardized bundle of metabolic modulators and assess the safety of including the anabolic steroid oxandrolone within it. Methods: This retrospective observational study constituted all patients in whom the metabolic bundle including oxandrolone therapy was applied. The other elements of the metabolic bundle consisted of early surgical burn excision within seven days to completion, early active mobilization, increased ambient room temperature, expediated carbohydrate and protein rich enteral feeding with glutamine and trace element supplements (such as copper and zinc). Finally, administration of propranolol as a non-selective beta-blocker. Data collection was through review of the patient data management system focusing on the outcome criteria and hepatic blood values. Results: The study looked at fifty consecutive patients meeting the inclusion criteria. Median patient age and burned total body surface area (TBSA) were 62 years [51.75; 73] and 33.75% [24.75; 51] respectively with an abbreviated burn severity index (ABSI) of 10 [9; 10.25]. Definitive surgical burn wound excision was completed in 44 patients [88%] within 7 days. 39 patients (78%) received propranolol over a therapeutic period of 29 days [19; 44]. Glutamine was supplemented in 45 patients (90%), while zinc and copper were applied to 42 (84%) and 31 (62%) respectively. Significant low zinc values were noted at therapeutic onset (6.5 mmol/l [4.7; 7.9]) requiring sustained substitution over 37.5 days [22; 46.75]). In respect of the inclusion criteria, all patients received oxandrolone at 20 mg/day [20; 20]. This was commenced on day 6.5 [4; 14] post burn injury and continued over 26 days [19; 31]. Despite a transitory elevation of hepatic enzyme values (ALT, GGT), these were only clinically relevant (>10 µmol/l*S) in 2.4% and 4.6% of all measurements respectively. None were sufficiently of concern to merit cessation of treatment. Conclusion: The application of a standardised bundle of metabolic treatment options of severe burns injured patients is reliable, repeatable and safe. Potential concerns of oxandrolone treatment regarding hepatic compromise remain unfounded.

Perioperative management of patients with severe pulmonary hypertension in major orthopedic surgery: experience-based recommendations.

INTRODUCTION: It is known that pulmonary hypertension is associated with worse outcome in both cardiac and non-cardiac surgery. The aims of our retrospective analysis were to evaluate the outcomes of our patients with pulmonary hypertension undergoing major orthopedic surgery and to give experience-based recommendations for the perioperative management. MATERIAL AND METHODS: From 92 patients with pulmonary hypertension undergoing different kinds of surgical procedures from 2011-2014 in a tertiary academic hospital we evaluated 16 patients with major orthopedic surgery for perioperative morbidity and mortality. RESULTS: Regarding the in-hospital morbidity and mortality, one patient died postoperatively due to pulmonary infection and right heart failure (6.25%) and 6 patients suffered significant postoperative complications (37.5%; bleeding = 1, infection = 1, wound healing deficits = 3; dysrhythmia = 1). CONCLUSION: Our data show that major orthopedic surgery is feasible with satisfactory outcome even in cases of severe pulmonary hypertension by an individualized, disease-adapted interdisciplinary treatment concept.

Differences between state entropy and bispectral index during analysis of identical electroencephalogram signals: a comparison with two randomised anaesthetic techniques.

BACKGROUND: It is claimed that bispectral index (BIS) and state entropy reflect an identical clinical spectrum, the hypnotic component of anaesthesia. So far, it is not known to what extent different devices display similar index values while processing identical electroencephalogram (EEG) signals. OBJECTIVE: To compare BIS and state entropy during analysis of identical EEG data. Inspection of raw EEG input to detect potential causes of erroneous index calculation. DESIGN: Offline re-analysis of EEG data from a randomised, single-centre controlled trial using the Entropy Module and an Aspect A-2000 monitor. SETTING: Klinikum rechts der Isar, Technische Universität München, Munich. PATIENTS: Forty adult patients undergoing elective surgery under general anaesthesia. INTERVENTIONS: Blocked randomisation of 20 patients per anaesthetic group (sevoflurane/remifentanil or propofol/remifentanil). Isolated forearm technique for differentiation between consciousness and unconsciousness. MAIN OUTCOME MEASURES: Prediction probability (PK) of state entropy to discriminate consciousness from unconsciousness. Correlation and agreement between state entropy and BIS from deep to light hypnosis. Analysis of raw EEG compared with index values that are in conflict with clinical examination, with frequency measures (frequency bands/Spectral Edge Frequency 95) and visual inspection for physiological EEG patterns (e.g. beta or delta arousal), pathophysiological features such as high-frequency signals (electromyogram/high-frequency EEG or eye fluttering/saccades), different types of electro-oculogram or epileptiform EEG and technical artefacts. RESULTS: PK of state entropy was 0.80 and of BIS 0.84; correlation coefficient of state entropy with BIS 0.78. Nine percent BIS and 14% state entropy values disagreed with clinical examination. Highest incidence of disagreement occurred after state transitions, in particular for state entropy after loss of consciousness during sevoflurane anaesthesia. EEG sequences which led to false 'conscious' index values often showed high-frequency signals and eye blinks. High-frequency EEG/electromyogram signals were pooled because a separation into EEG and fast electro-oculogram, for example eye fluttering or saccades, on the basis of a single EEG channel may not be very reliable. These signals led to higher Spectral Edge Frequency 95 and ratio of relative beta and gamma band power than EEG signals, indicating adequate unconscious classification. The frequency of other artefacts that were assignable, for example technical artefacts, movement artefacts, was negligible and they were excluded from analysis. CONCLUSION: High-frequency signals and eye blinks may account for index values that falsely indicate consciousness. Compared with BIS, state entropy showed more false classifications of the clinical state at transition between consciousness and unconsciousness.

Comparison of Aintree and Fastrach techniques for low-skill fibreoptic intubation in patients at risk of secondary cervical injury: a randomised controlled trial.

BACKGROUND: We compared two methods of asleep fibreoptic intubation in patients at risk of secondary cervical injury: the Aintree Intubation Catheter via a classic laryngeal mask airway (cLMA) versus the Fastrach technique via the intubating laryngeal mask airway (iLMA). OBJECTIVE: To test which system has the highest rate of successful intubations in the clinical setting. DESIGN: A randomised controlled study. SETTING: Single-centre, between 2007 and 2010. PATIENTS: We randomly allocated 80 patients (30 women and 50 men) who underwent elective neurosurgery of the cervical spine to either group, placed in a neutral position and wearing a soft cervical collar. Entry criteria were ASA status 1 to 3, age 18 to 80 years and written informed consent. Exclusion criteria were patients with cervical instability, known or predicted difficult airway, BMI greater than 40  kg  m⁻² and symptomatic gastro-oesophageal reflux. INTERVENTIONS: Two anaesthetists who were experienced in both techniques performed all anaesthesia procedures within the study. There was a maximum of three attempts for performing each technique. MAIN OUTCOME MEASURES: The primary outcome was the rate of successful fibreoptic intubation in a neutral position. We also investigated the timing sequence for both techniques, the Brimacombe and Berry Bronchoscopy Score, and differences in technical aspects. RESULTS: All 40 patients in the Aintree group but only 31 patients in the Fastrach group were intubated successfully. Thus, fibreoptic intubation failed significantly less using the Aintree technique (P = 0.002). For secondary outcomes, the cLMA was faster (260 versus 289  s, P = 0.039) and easier (P = 0.036) to insert than the iLMA. The fibreoptic view of the glottis according to the Brimacombe and Berry Bronchoscopy Score was better (P = 0.016) and the tracheal tube was easier to insert (P = 0.010) in the Aintree group. CONCLUSION: Fibreoptic intubation using the Aintree system was more successful than the Fastrach technique in our population of patients in a neutral position wearing a soft cervical collar. The differences in the time to successful intubation between the two groups are unlikely to be clinically relevant.