Joachim Schmidt

Intraoperative neuromuscular monitoring (IONM) is a widespread procedure to identify and protect the recurrent laryngeal nerve (RLN) during thyroid surgery. However, for left thoracic surgery with high risk of RLN injury, both reliable recurrent laryngeal nerve monitoring and one-lung ventilation could interfere. In this prospective study, a new method for IONM during one-lung ventilation combining RLN monitoring with an electromyographic (EMG) endotracheal tube (ETT) and lung separation using the EZ-Blocker (EZB) is described and its clinical feasibility and effectiveness were assessed. A total of 14 patients undergoing left upper lobe surgery and left upper mediastinal lymph node dissection were enrolled. The EZB was introduced and positioned without any problems and sufficient lung collapse was achieved in all patients. No tracheobronchial injuries or immediate complications occurred. A stable EMG signal was present in all patients and no RLN palsy and no negative side effects of the NIM EMG ETT or the EZB were observed postoperatively. The described method is technically feasible, easy to apply and save. It provides both reliable IONM and independent lung separation for optimal surgical exposure. The combined use of the EZB and the NIM EMG ETT might reduce the risk for RLN palsy and impaired lung separation during left thoracic surgery with high risk for RLN injury.

Background: The effects of environmental changes on the somato-sensory system during long-distance air ambulance flights need to be further investigated. Changes in nociceptive capacity are conceivable in light of previous studies performed under related environmental settings. We used standardized somato-sensory testing to investigate nociception in healthy volunteers during air-ambulance flights. Methods: Twenty-five healthy individuals were submitted to a test compilation analogous to the quantitative sensory testing battery – performed during actual air-ambulance flights. Measurements were paired around the major changes of external factors during take-off/climb and descent/landing. Bland-Altman-Plots were calculated to identify possible systemic effects. Results: Bland-Altman-analyses suggest that the thresholds of stimulus detection and pain as well as above-threshold pain along critical waypoints of travel are not subject to systemic effects but instead demonstrate random variations. Conclusions: We provide a novel description of a real-life experimental setup and demonstrate the general feasibility of performing somato-sensory testing during ambulance flights. No systematic effects on the nociception of healthy individuals were apparent from our data. Our findings open up the possibility of future investigations into potential effects of ambulance flights on patients suffering acute or chronic pain.

Aspiration is a main contributor to morbidity and mortality in anaesthesia. The ideal patient positioning for rapid sequence induction remains controversial. A head-down tilt and full cervical spine extension (Sellick) might prevent aspiration but at the same time compromise airway management. We aimed to determine the influence of three different positions during induction of general anaesthesia on the volume of aspirate and on participants’ airway management. Eighty-four anaesthetic trainees and consultants participated in a prospective randomised simulation study. Anaesthesia was induced in reverse Trendelenburg position (+ 15°) in a manikin capable of dynamic fluid regurgitation. Participants were randomised to change to Trendelenburg position (− 15°) a) as soon as regurgitation was noticed, b) as soon as ‘patient’ had been anaesthetised, and c) as soon as ‘patient’ had been anaesthetised and with full cervical spine extension (Sellick). Primary endpoints were the aspirated volume and the time to intubation. Secondary endpoints were ratings of the laryngoscopic view and the intubation situation (0–100 mm). Combining head-down tilt with Sellick position significantly reduced aspiration (p < 0.005). Median time to intubate was longer in Sellick position (15 s [8–30]) as compared with the head in sniffing position (10 s [8–12.5]; p < 0.05). Participants found laryngoscopy more difficult in Sellick position (39.3 ± 27.9 mm) as compared with the sniffing position (23.1 ± 22.1 mm; p < 0.05). Both head-down tilt intubation situations were considered equally difficult: 34.8 ± 24.6 mm (Sniffing) vs. 44.2 ± 23.1 mm (Sellick; p = n.s). In a simulated setting, using a manikin-based simulator capable of fluid regurgitation, a − 15° head-down tilt with Sellick position reduced the amount of aspirated fluid but increased the difficulty in visualising the vocal cords and prolonged the time taken to intubate. Assessing the airway management in the identical position in healthy patients without risk of aspiration might be a promising next step to take.

In certain clinical situations the insertion of a double-lumen tube (DLT) for one-lung ventilation (OLV) is not feasible or unfavorable. In these cases, the EZ-Blocker (EZB) may serve as an alternative. The aim of our analysis was to report on the clinical applications and our experience with the EZB for one-lung ventilation in 100 patients undergoing thoracic surgery. All anesthetic records from patients older than 18 years of age undergoing general anesthesia in the department of thoracic surgery with intraoperative use of an EZB for OLV at the University Hospital of Erlangen in four consecutive years were analyzed retrospectively. Most frequently, EZB was used in difficult airway (27%) and for surgical procedures with high risk for left recurrent laryngeal nerve injury (21%), followed by application in intubated (12%) or tracheostomized (11%) patients. 11% of the patients had an increased risk of gastric regurgitation. Almost all EZBs were placed free of complications (99%). Clinically sufficient lung collapse was achieved in all patients. No serious airway injuries or immediate complications were documented. The EZB is an efficient, easy-to-use and safe airway device and enables OLV in several clinical situations, when conventional DLTs are not feasible or less favorable. Three major applications were depicted from the data: expected difficult airway, surgical procedures with necessity of intraoperative recurrent laryngeal nerve monitoring and already intubated or tracheostomized patients.

Prehospital intravenous access provides the opportunity to sample blood from an emergency patient at the earliest possible moment in the course of acute illness and in a state prior to therapeutic interventions. Our study investigates the pre-analytical stability of biomarkers in prehospital emergency medicine and will answer the question whether an approach of blood sampling out in the field will deliver valid laboratory results. We prepared pairs of blood samples from healthy volunteers and volunteering patients post cardio-thoracic surgery. While one sample set was analysed immediately, the other one was subjected to a worse-than-reality treatment of 60 min time-lapse and standardized mechanical forces outside of the hospital through actual ambulance transport. We investigated 21 parameters comprising blood cells, coagulation tests, electrolytes, markers of haemolysis and markers of cardiac ischemia. Bland-Altman analysis was used to investigate differences between test groups. Differences between test groups were set against the official margins of test accuracy as given by the German Requirements for Quality Assurance of Medical Laboratory Examinations. Agreement between immediate analysis and our prehospital treatment is high as demonstrated by Bland-Altman plotting. Mechanical stress and time delay do not produce a systematic bias but only random inaccuracy. The limits of agreement for the tested parameters are generally within clinically acceptable ranges of variation and within the official margins as set by the German Requirements for Quality Assurance of Medical Laboratory Examinations. We subjected blood samples to a standardized treatment marking a worse-than-reality scenario of prehospital time delay and transport. Biomarkers including indicators of myocardial ischemia showed high pre-analytical stability. We conclude the validity of blood samples from a prehospital environment.

Introduction: The critically-ill undergoing inter-hospital transfers commonly receive sedatives in continuation of their therapeutic regime or to facilitate a safe transfer shielded from external stressors. While sedation assessment is well established in critical care in general, there is only little data available relating to the special conditions during patient transport and their effect on patient sedation levels. The aim of this prospective study was to investigate the feasibility and relationship of clinical sedation assessment (Richmond Agitation-Sedation Scale (RASS)) and objective physiological monitoring (bispectral index (BIS)) during patient transfers in our Mobile-ICU. Methods: The levels of sedation of 30 pharmacologically sedated patients were evaluated at 12 to 17 distinct measurement points spread strategically over the course of a transfer by use of the RASS and BIS. To investigate the relation between the RASS and the BIS, Spearman’s squared rank correlation coefficient (ρ²) and the Kendall’s rank correlation coefficient (τ) were calculated. The diagnostic value of the BIS with respect to the RASS was investigated by its sensitivity and positive predictive value for possible patient awakening. Therefore, measurements were dichotomized considering a clinically sensible threshold of 80 for BIS-values and classifying RASS values being nonnegative. Results: Spearman’s rank correlation resulted to ρ² = 0.431 (confidence interval (CI) = 0.341 to 0.513). The Kendall’s correlation coefficient was calculated as τ = 0.522 (CI = 0.459 to 0.576). Awakening of patients (RASS ≥0) was detected by a BIS value of 80 and above with a sensitivity of 0.97 (CI = 0.89 to 1.00) and a positive predictive value of 0.59 (CI = 0.45 to 0.71). Conclusions: Our study demonstrates that the BIS-Monitor can be used for the assessment of sedation levels in the intricate environment of a Mobile-ICU, especially when well-established clinical scores as the RASS are impracticable. The use of BIS is highly sensitive in the detection of unwanted awakening of patients during transfers.

Introduction: It is well known that etomidate may cause adrenal insufficiency. However, the clinical relevance of adrenal suppression after a single dose of etomidate remains vague. The aim of this study was to investigate the association between the administration of a single dose of etomidate or an alternative induction regime ahead of major cardiac surgery and clinical outcome parameters associated with adrenal suppression and onset of sepsis. Methods: The anesthesia and intensive care unit (ICU) records from patients undergoing cardiac surgery over five consecutive years (2008 to 2012) were retrospectively analyzed. The focus of the analysis was on clinical parameters like mortality, ventilation hours, renal failure, and sepsis-linked serum parameters. Multivariate analysis and Cox regression were applied to derive the results. Results: In total, 3,054 patient records were analyzed. A group of 1,775 (58%) patients received a single dose of etomidate; 1,279 (42%) patients did not receive etomidate at any time. There was no difference in distribution of age, American Society of Anesthesiologists physical score, duration of surgery, and Acute Physiology and Chronic Health Evaluation II score. Postoperative data showed no significant differences between the two groups in regard to mortality (6.8% versus 6.4%), mean of mechanical ventilation hours (21.2 versus 19.7), days in the ICU (2.6 versus 2.5), hospital days (18.7 versus 17.4), sepsis-associated parameters, Sequential Organ Failure Assessment score, and incidence of renal failure. Administration of etomidate showed no significant influence (P = 0.6) on hospital mortality in the multivariate Cox analysis. Conclusions: This study found no evidence for differences in key clinical outcome parameters based on anesthesia induction with or without administration of a single dose of etomidate. In consequence, etomidate might remain an acceptable option for single-dose anesthesia induction.

This study was designed to assess efficacy and safety in the treatment of perivascular malignant liver lesions using percutaneous, computed tomography (CT)-guided irreversible electroporation (IRE). Fourteen patients (mean age 58 ± 11 years) with 18 malignant liver lesions were consecutively enrolled in this study. IRE was performed in patients not eligible for surgery and lesions abutting large vessels or bile ducts. Follow-up exams were performed using multislice-CT (MS-CT) or MRI. Medium lesion diameter was 20 ± 5 mm. Ten of 14 (71 %) were successfully treated with no local recurrence to date (mean follow-up 388 ± 160 days). One case left initial tumor control unclear and additional RFA was performed 4 weeks after IRE. Complications occurred in 4 of 14 (29 %) cases. In one case, intervention was terminated and abdominal bleeding required laparotomy. In two cases, a postinterventional hematothorax required intervention. In another case, abdominal bleeding could be managed conservatively. No complications related to the bile ducts occurred. Percutaneous IRE seems to be effective in perivascular lesions but is associated with a higher complication rate compared with thermoablative techniques.

Background Hypoxemia caused by difficulties in airway management presents a major cause for perioperative morbidity and mortality. The ability to predict difficult laryngoscopy more accurately would enable anesthesiologists to take specific precautions to reduce airway risks and prevent patient-threatening events. Methods Over a 6-year period of time, all anesthesia records with a documented direct laryngoscopic view were retrieved from the electronic data management system and statistically processed. The Cormack–Lehane four-point scale of grading laryngoscopy was used to assess visibility of the vocal cords. Results Of 102,306 cases, the overall rate of difficult laryngoscopy was 4.9 %. Male gender (6.5 %), Mallampati score III and IV (17.3 %), obesity with a BMI ≥35 kg/m² (6.1 %), as well as physical status ASA III or IV (6.2 %), were identified as risk factors for difficult laryngoscopy. Patients undergoing surgery in the departments of oromaxillofacial (8.9 %), ear nose throat surgery (ENT) (7.4 %), and cardiac surgery (7.0 %) showed the highest rates of difficult laryngoscopy. Conclusions The results indicate that the risk for difficult airway situations might substantially differ between surgical patient groups. In hospitals with departmental structures and spatially separated operating rooms, the deduction might be increased awareness and particular structural preparation for difficult airway situations in the respective subspecialties.