Managing One-Lung Ventilation in Tracheostomized Patients: A 6-Year Retrospective Analysis.

BACKGROUND: To ensure safe and optimal surgical conditions in thoracic surgery, one-lung ventilation is crucial. Various techniques exist to achieve one-lung ventilation. Tracheotomized patients who require one-lung ventilation represent a unique and rare subgroup that demands specialized knowledge and skills. The very limited literature has discussed alternative methods, no randomized controlled trials have addressed this issue yet. METHODS: We performed a retrospective analysis of patients who underwent one-lung ventilation in the Department of Thoracic Surgery of a German University Hospital between 2016 and 2021. The study assessed patient demographics, airway management techniques, ventilation parameters, and adverse events. RESULTS: In 3,197 anesthesia procedures during the observation period, 152 patients had an existing tracheostomy, of which 56 required one-lung ventilation. Among others in 42 cases, a tracheostomy tube was combined with a bronchial blocker, and in 10 cases, a double-lumen tracheostomy tube was used. There were no severe complications. Intraoperative dislocations that required repositioning of the device occurred in six patients (13.3%) with bronchial blockers and one patient with double-lumen tracheostomy tube (10%). CONCLUSION: The management of one-lung ventilation in tracheotomized patients presents unique challenges. While double-lumen tracheostomy tubes have specific advantages, we recommend considering their use carefully. For most tracheotomized patients, bronchial blockers in conjunction with a tracheostomy tube are used, which offers safety and practicality, irrespective of the tracheostomy's age or type. Further research and randomized controlled trials are warranted to establish best practices for one-lung ventilation in this unique patient population.

Rapid response flow cytometric assay for the detection of antibody responses to SARS-CoV-2.

SARS-CoV-2 has emerged as a previously unknown zoonotic coronavirus that spread worldwide causing a serious pandemic. While reliable nucleic acid-based diagnostic assays were rapidly available, only a limited number of validated serological assays were available in the early phase of the pandemic. Here, we evaluated a novel flow cytometric approach to assess spike-specific antibody responses.HEK 293T cells expressing SARS-CoV-2 spike protein in its natural confirmation on the surface were used to detect specific IgG and IgM antibody responses in patient sera by flow cytometry. A soluble angiotensin-converting-enzyme 2 (ACE-2) variant was developed as external standard to quantify spike-specific antibody responses on different assay platforms. Analyses of 201 pre-COVID-19 sera proved a high assay specificity in comparison to commercially available CLIA and ELISA systems, while also revealing the highest sensitivity in specimens from PCR-confirmed SARS-CoV-2-infected patients. The external standard allowed robust quantification of antibody responses among different assay platforms. In conclusion, our newly established flow cytometric assay allows sensitive and quantitative detection of SARS-CoV-2-specific antibodies, which can be easily adopted in different laboratories and does not rely on external supply of assay kits. The flow cytometric assay also provides a blueprint for rapid development of serological tests to other emerging viral infections.

Testing mechanical chest compression devices of different design for their suitability for prehospital patient transport - a simulator-based study.

BACKGROUND: Mechanical chest compression (mCPR) offers advantages during transport under cardiopulmonary resuscitation. Little is known how devices of different design perform en-route. Aim of the study was to measure performance of mCPR devices of different construction-design during ground-based pre-hospital transport. METHODS: We tested animax mono (AM), autopulse (AP), corpuls cpr (CC) and LUCAS2 (L2). The route had 6 stages (transport on soft stretcher or gurney involving a stairwell, trips with turntable ladder, rescue basket and ambulance including loading/unloading). Stationary mCPR with the respective device served as control. A four-person team carried an intubated and bag-ventilated mannequin under mCPR to assess device-stability (displacement, pressure point correctness), compliance with 2015 ERC guideline criteria for high-quality chest compressions (frequency, proportion of recommended pressure depth and compression-ventilation ratio) and user satisfaction (by standardized questionnaire). RESULTS: All devices performed comparable to stationary use. Displacement rates ranged from 83% (AM) to 11% (L2). Two incorrect pressure points occurred over 15,962 compressions (0.013%). Guideline-compliant pressure depth was > 90% in all devices. Electrically powered devices showed constant frequencies while muscle-powered AM showed more variability (median 100/min, interquartile range 9). Although physical effort of AM use was comparable (median 4.0 vs. 4.5 on visual scale up to 10), participants preferred electrical devices. CONCLUSION: All devices showed good to very good performance although device-stability, guideline compliance and user satisfaction varied by design. Our results underline the importance to check stability and connection to patient under transport.

Workload and influencing factors in non-emergency medical transfers: a multiple linear regression analysis of a cross-sectional questionnaire study.

BACKGROUND: Human workload is a key factor for system performance, but data on emergency medical services (EMS) are scarce. We investigated paramedics' workload and the influencing factors for non-emergency medical transfers. These missions make up a major part of EMS activities in Germany and are growing steadily in number. METHODS: Paramedics rated missions retrospectively through an online questionnaire. We used the NASA-Task Load Index (TLX) to quantify workload and asked about a variety of medical and procedural aspects for each mission. Teamwork was assessed by the Weller teamwork measurement tool (TMT). With a multiple linear regression model, we identified a set of factors leading to relevant increases or decreases in workload. RESULTS: A total of 194 non-emergency missions were analysed. Global workload was rated low (Mean = 27/100). In summary, 42.8% of missions were rated with a TLX under 20/100. TLX subscales revealed low task demands but a very positive self-perception of performance (Mean = 15/100). Teamwork gained high ratings (Mean TMT = 5.8/7), and good teamwork led to decreases in workload. Aggression events originating from patients and bystanders occurred frequently (n = 25, 12.9%) and increased workload significantly. Other factors affecting workload were the patient's body weight and the transfer of patients with transmittable pathogens. CONCLUSION: The workload during non-emergency medical transfers was low to very low, but performance perception was very positive, and no indicators of task underload were found. We identified several factors that led to workload increases. Future measures should attempt to better train paramedics for aggression incidents, to explore the usefulness of further technical aids in the transfer of obese patients and to reconsider standard operating procedures for missions with transmittable pathogens.

Influence of Cardiac Output on the Pharmacokinetics of Sufentanil in Anesthetized Pigs.

BACKGROUND: Sufentanil is used for general anesthesia and analgesia. The study aim was to determine the effect of pharmacologically induced changes in cardiac output on the pharmacokinetics of sufentanil in anesthetized pigs. METHODS: Twenty-four pigs were randomly assigned to low, high, and control cardiac output groups. Cardiac output was decreased or increased from baseline by at least 40%, or maintained within ± 10% of baseline, respectively. Sufentanil was administered as a bolus followed by a continuous infusion for 120 min. Timed arterial samples were drawn for sufentanil concentration measurements. RESULTS: Data from 20 animals were analyzed. The cardiac outputs (means ± SD) were 2.9 ± 0.7, 5.4 ± 0.7, and 9.6 ± 1.6 l/min in the low, control, and high cardiac output groups, respectively. The parameters of the two-compartment pharmacokinetic model for these cardiac outputs were: CL1: 0.9, 1.2, and 1.7 l/min; CL2: 0.9, 3.1, and 6.9 l/min; V1: 1.6, 2.9, and 5.2 l; and V2: 27.5, 47.0, and 79.8 l, respectively. Simulated sufentanil doses to maintain a target plasma concentration of 0.5 ng/ml for 3 h were 99.5, 128.6, and 157.6 µg for cardiac outputs of 3, 5, and 7 l/min, respectively. The context-sensitive half-times for these cardiac outputs increased from 3.1 to 19.9 and 25.9 min, respectively. CONCLUSIONS: Cardiac output influences the pharmacokinetics of sufentanil. Simulations suggest that in the case of increased cardiac output, the dose should be increased to avoid inadequate drug effect at the expense of prolonged recovery, whereas for low cardiac output the dose should be reduced, and a faster recovery may be expected.

Comparison of Metal and Plastic Disposable Laryngoscope Blade with Reusable Macintosh Blade in Difficult and Inhalation Injury Airway Scenario: A Manikin Study.

BACKGROUND: Single-use plastic blades (SUPB) and single-use metal blades (SUMB) for direct laryngoscopy and tracheal intubation have not yet been compared with reusable metal blades (RUMB) in difficult airway scenarios. OBJECTIVE: The purpose of our manikin study was to compare the effectiveness of these different laryngoscope blades in a difficult airway scenario, as well as in a difficult airway scenario with simulated severe inhalation injury. METHODS: Thirty anesthetists performed tracheal intubation (TI) with each of the three laryngoscope blades in the two scenario manikins. RESULTS: In the inhalation injury scenario, SUPB were associated with prolonged intubation times when compared with the metal blades. In the inhalation injury scenario, both metal laryngoscope blades provided a quicker, easier, and safer TI. In the difficult airway scenario, intubation times were significantly prolonged in the SUPB group in comparison to the RUMB group, but there were no significant differences between the SUPB and the SUMB. In this scenario, the RUMB demonstrated the shortest intubation times and seems to be the most effective device. CONCLUSIONS: Generally, results are in line with previous studies showing significant disadvantages of SUPB in both manikin scenarios. Therefore, metal blades might be beneficial, especially in the airway management of patients with inhalation injury.

Ischaemia-related cell damage in extracorporeal preserved tissue - new findings with a novel perfusion model.

Tissue undergoing free transfer in transplant or reconstructive surgery always is at high risk of ischaemia-related cell damage. This study aims at assessing different procedures using an extracorporeal perfusion and oxygenation system to investigate the expression of hypoxia inducible factor (HIF)-1-α as marker for hypoxia and of the pro-apoptotic protein Caspase-3 in skeletal muscle to elucidate potential improvements in tissue conservation. Twenty-four porcine rectus abdominis muscles were assigned to five different groups and examined after they had been extracorporeally preserved for 60 min. time. Group I was left untreated (control), group II was perfused with a cardioplegic solution, group III was flushed with 10 ml of a cardioplegic solution and then left untreated. Group IV and V were perfused and oxygenated with either an isotone crystalloid solution or a cardioplegic solution. Among others, immunohistochemistry (Caspase-3 and HIF-1-α) of muscle samples was performed. Furthermore, oxygen partial pressure in the perfusate at the arterial and venous branch was measured. Expression of Caspase-3 after 60 min. was reduced in all groups compared to the control group. Furthermore, all groups (except group III) expressed less HIF-1-α than the control group. Oxygenation leads to higher oxygen levels at the venous branch compared to groups without oxygenation. Using an extracorporeal perfusion and oxygenation system cell damage could be reduced as indicated by stabilized expressions of Caspase-3 and HIF-1-α for 60 min. of tissue preservation. Complete depletion of oxygen at the venous branch can be prevented by oxygenation of the perfusate with ambient air.

Video double-lumen tube for one lung ventilation: implementation and experience in 343 cases of routine clinical use during the first 20 months of the SARS-CoV-2 pandemic.

BACKGROUND: Double-lumen tubes (DLTs) are the preferred device for lung isolation. Conventional DLTs (cDLT) need a bronchoscopic position control. Visualisation of correct DLT positioning could be facilitated by the use of a video double-lumen tube (vDLT). During the SARS-CoV-2-pandemic, avoiding aerosol-generation was suggesting using this device. In a large retrospective series, we report both general and pandemic related experiences with the device. METHODS: All anesthesia records from patients aged 18 years or older undergoing surgery from April 1st, 2020 to December 31st, 2021 in the department of thoracic surgery requiring intraoperative lung isolation were analyzed retrospectively. RESULTS: During the investigation period 343 left-sided vDLTs (77.4%) and 100 left-sided cDLTs (22.6%) were used for one lung ventilation. In the vDLT group bronchoscopy could be reduced by 85.4% related to the cDLT group. Additional bronchoscopy to reach or maintain correct position was needed in 11% of the cases. Other bronchoscopy indications occured in 3.6% of the cases. With cDLT, in 1% bronchoscopy for other indications than conforming position was observed. CONCLUSIONS: The Ambu® VivaSight™ vDLT is an efficient, easy-to-use and safe airway device for the generation of one lung ventilation in patients undergoing thoracic surgery. The vDLT implementation was achieved easily with full interchangeability to the left-sided cDLT. Using the vDLT can reduce the need for aerosol-generating bronchoscopic interventions by 85.4%. Continuous video view to the carina enabling position monitoring of the DLT without need for bronchoscopy might be beneficial for both employee's and patient's safety.

Early Intravenous Magnesium Sulfate and Its Impact on Cerebral Vasospasm as well as Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage: A Retrospective Matched Case-Control Analysis.

BACKGROUND: Magnesium sulfate (MgSO4) is a potential neuroprotective agent for patients with aneurysmal subarachnoid hemorrhage (SAH). We analyzed the effect of early application of intraoperative intravenous MgSO4 and compared cerebral vasospasm (CV), delayed cerebral ischemia (DCI), and neurological outcome in 2 patient cohorts. METHODS: A retrospective matched-pair analysis from patients at a single center in Germany was performed without (group A) and with (group B) MgSO4 application <24 hours after diagnosis. Pairs were matched according to the known risk factors for DCI and CV (age, Fisher grade, smoking, severity of SAH). Incidence of CV and DCI and neurological outcome using the modified Rankin Scale score 3 and 12 months after SAH were recorded. RESULTS: The inclusion criteria were met by 196 patients. After risk stratification, 48 patients were included in the final analysis (age 54.2 ± 8.1 years; 30 women and 18 men) and were assigned to group A (n = 24) or group B (n = 24). CV occurred less frequently in group B (33%) than in group A (46%). Likewise, DCI was present in 13% in group B compared with 42% in group A. After 12 months, 22 patients in group B had a favorable functional outcome (modified Rankin Scale score 0-3) compared with 15 patients in group A. CONCLUSIONS: In this study, the incidence of CV and DCI was lower in patients receiving intravenous MgSO4 within 24 hours after aneurysmal SAH onset. Favorable functional outcome was more likely in the MgSO4 group after 12 months of follow-up.

Incidence and predictors of poor laryngoscopic view in children undergoing pediatric cardiac surgery.

OBJECTIVE: Previous investigations reported a higher incidence of poor laryngoscopic views in pediatric patients undergoing cardiac surgery. The objective of this study was to analyze why children undergoing cardiac surgery have such an increased incidence of poor laryngoscopic views during anesthesia induction. DESIGN: This study was designed as a retrospective analysis. SETTING: This analysis was based on a single-center cohort of a university hospital. PARTICIPANTS: One thousand one hundred seventy-seven general anesthesia procedures, including a direct laryngoscopic view over a period of 6 consecutive years, in pediatric patients undergoing cardiac surgery. INTERVENTIONS: Because of the retrospective character of this study, there were no study-related interventions. MEASUREMENTS AND MAIN RESULTS: Poor laryngoscopic views were defined as Cormack and Lehane (CML) grade III and IV. The overall incidence of poor laryngoscopic views was 3.5%. In patients younger than 1 year of age, the incidence of CML III or IV was significantly higher than in the older patients (5.6% v 1.7%). None of the patients with CML III/IV findings had Down syndrome; whereas in 9 of 41 patients with CML grade III/IV, a concomitant congenital syndrome like DiGeorge syndrome or CHARGE syndrome was found. CONCLUSIONS: The general incidence of CML III/IV findings during the induction of anesthesia for pediatric cardiac surgery is more than twice as high as reported in unselected pediatric cohorts. In patients below 1 year of age and in male patients, difficult laryngoscopy is more frequent. Concomitant Down syndrome was not associated with difficult laryngoscopy.

Incidence and predictors of difficult laryngoscopy in 11,219 pediatric anesthesia procedures.

OBJECTIVE: Difficult laryngoscopy in pediatric patients undergoing anesthesia. AIM: This retrospective analysis was conducted to investigate incidence and predictors of difficult laryngoscopy in a large cohort of pediatric patients receiving general anesthesia with endotracheal intubation. BACKGROUND: Young age and craniofacial dysmorphy are predictors for the difficult pediatric airway and difficult laryngoscopy. For difficult laryngoscopy, other general predictors are not yet described. METHODS: Retrospectively, from a 5-year period, data from 11.219 general anesthesia procedures in pediatric patients with endotracheal intubation using age-adapted Macintosh blades in a single center (university hospital) were analyzed statistically. RESULTS: The overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was 1.35%. In patients younger than 1 year, the incidence of CML III or IV was significantly higher than in the older patients (4.7% vs 0.7%). ASA Physical Status III and IV, a higher Mallampati Score (III and IV) and a low BMI were all associated (P < 0.05) with difficult laryngoscopy. Patients undergoing oromaxillofacial surgery and cardiac surgery showed a significantly higher rate of CML III/IV findings. CONCLUSION: The general incidence of difficult laryngoscopy in pediatric anesthesia is lower than in adults. Our results show that the risk of difficult laryngoscopy is much higher in patients below 1 year of age, in underweight patients and in ASA III and IV patients. The underlying disease might also contribute to the risk. If the Mallampati score could be obtained, prediction of difficult laryngoscopy seems to be reliable. Our data support the existing recommendations for a specialized anesthesiological team to provide safe anesthesia for infants and neonates.

Online oxygen measurements in ex vivo perfused muscle tissue in a porcine model using dynamic quenching methods.

INTRODUCTION: Transplantation of autologous free tissue flaps is the best applicable technique for treating large and complex tissue defects and still has one major failure criterion. Tissue--and in particular muscle tissue--is strongly sensitive to ischemia, thus after a critical period of oxygen depletion the risk of a partial or total flap loss is high. MATERIALS AND METHODS: For that reason a miniaturized ex vivo perfusion system has been developed, that supplies the tissue during operational delays. The purpose of this study was to determine the oxygenation levels during such a perfusion using different perfusates and therefore to objectify if a complementary oxygenation unit is required to improve perfusion quality. The oxygen levels of the tissue, as well of the perfusate, were measured by using minimal invasive optical oxygen sensors that are based on dynamic quenching. The ex vivo perfused tissue was the porcine rectus abdominis muscle. RESULTS: Results show, that during perfusion with heparinized crystalloid fluid (Jonosteril) and heparinized autologous whole blood, additional oxygenation of the perfusion reactor led to different ex vivo oxygen tissue saturations, which can be detected by dynamic quenching. CONCLUSION: Dynamic quenching methods are a promising and valuable technique to perform online oxygen measurements in ex vivo perfused muscle tissue in a porcine model.

Comparison of two electromyographical endotracheal tube systems for intraoperative recurrent laryngeal nerve monitoring: reliability and side effects.

BACKGROUND: Recurrent laryngeal nerve (RLN) monitoring systems should be reliable and safe. Monitoring via electromyographical systems on an endotracheal tube (ETT) is widely spread. The MagStim™ system consists of an adhesive electrode to be fixed on an endotracheal tube. The Xomed™ endotracheal tube provides integrated electrodes. Reliability and side effects had never been compared. As both systems have very different morphological properties, we hypothesized that there might be differences in reliability and the incidence of side effects. METHODS: In a retrospective quality management analysis of 118 patients (MagStim™ electrode, 57 patients; Xomed™ ETT, 61 patients), we compared laryngeal side effects according to the Chilla score and detection rate of the RLN. RESULTS: Both systems had comparable detection rates of the RLN above 95%. Both electrode systems seemed to have similar reliability. Difficulties to detect the nerve were observed in seven patients (four with MagStim, three with Xomed). In the group with the Xomed™ ETT, significantly less mild laryngeal side effects were observed. CONCLUSION: Both MagStim™ and Xomed™ ETT were reliable in detecting the RLN. The Xomed™ ETT, however, might cause milder laryngeal side effects compared with the MagStim™ electrode.

Extracorporeal perfusion of free muscle flaps in a porcine model using a miniaturized perfusion system.

INTRODUCTION: The development of techniques in transplantation medicine--including various aspects--has made extraordinary progress within the past three decades. However, the transplantation of free tissue flaps with the common problem of limited ischemia time frames remains an area in which the understanding of mechanism during ischemia and reperfusion is still limited. Thus, similar to other organ transplantations, the prolongation of ischemic time and the possibility to perform an ex vivo perfusion is desirable. The purpose of this study was to create a closed and steady ex vivo perfusion system in order to analyze the possibility of using a miniaturized perfusion system for free muscle flaps that could also be clinically used for other solid organ transplantation. MATERIALS AND METHODS: The rectus abdominis muscles of six german pigs were used in the study. Each of these free muscle flaps was perfused for a period of 2 h using a pulsatile and closed pump perfusion system by cannulating the arterial and venous vessels of the flap pedicle. During the ex vivo perfusion parameters such as arterial and venous pressures were measured continuously. RESULTS: A total of six ex vivo, closed and steady perfusions have been successfully performed. The optimal arterial flow rate of ex vivo perfusion of rectus abdominis muscle flaps was evaluated to be 10 ml/min. The constant measurement of arterial (46 ± 13 mmHg) and venous (-1 ± 1 mmHg) pressure in this ex vivo setting showed steady parameters during a period for up to 2 h. CONCLUSION: The data of this study indicate that the ex vivo perfusion of free muscle flaps is technically feasible and a closed and steady circulation is manageable for a period of up to 2 h.

Job Satisfaction and Performance Orientation of Paramedics in German Emergency Medical Services-A Nationwide Survey.

(1) Background: Shortage of skilled workers is a relevant global health care problem. To remain competitive with other professions, job satisfaction is a critical issue; however, to date, there are no data available on the German EMS. This study aims to perform a statistical analysis of job satisfaction and performance orientation and to identify risk factors for low job satisfaction of paramedics in the German EMS. (2) Methods: Data were collected from 2590 paramedics through a nationwide cross-sectional survey, using the job satisfaction questionnaire by Neuberger and Allerbeck and the performance orientation questionnaire by Hippler and Krüger. Descriptive and regression statistical analysis were performed. (3) Results: The participants scored significantly lower than the reference sample on job satisfaction, with "organization and management" and "payment" being the lowest rated subscales. Around 9% of employees feared losing their jobs. While work attitude toward performance and success enhancement was high, fear of failure was also common. (4) Conclusions: Job satisfaction of paramedics in the German EMS is below that of the reference sample. Discontent with payment and organizational issues is common. Performance orientation is high, but fear of failure is frequent. Current and future efforts that aim at an attractive working environment should reflect on these findings.

Extracorporeal perfusion - reduced to a one-way infusion.

BACKGROUND: Extracorporeal perfusion (EP) is moving into focus of research in reconstructive and transplantation medicine for the preservation of amputates and free tissue transplants. The idea behind EP is the reduction of ischemia-related cell damage between separation from blood circulation and reanastomosis of the transplant. Most experimental approaches are based on a complex system that moves the perfusate in a circular course. OBJECTIVE AND METHODS: In this study, we aimed to evaluate if a simple perfusion by an infusion bag filled with an electrolyte solution can provide acceptable results in terms of flow stability, oxygen supply and viability conservation for EP of a muscle transplant. The results are compared to muscles perfused with a pump system as well as muscles stored under ischemic conditions after a one-time intravasal flushing with Jonosteril. RESULTS: With this simple method a sufficient oxygen supply could be achieved and functionality could be maintained between 3.35 times and 4.60 times longer compared to the control group. Annexin V positive nuclei, indicating apoptosis, increased by 9.7% in the perfused group compared to 24.4% in the control group. CONCLUSIONS: Overall, by decreasing the complexity of the system, EP by one-way infusion can become more feasible in clinical situations.

Interleukin-3 is a predictive marker for severity and outcome during SARS-CoV-2 infections.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide health threat. In a prospective multicentric study, we identify IL-3 as an independent prognostic marker for the outcome during SARS-CoV-2 infections. Specifically, low plasma IL-3 levels is associated with increased severity, viral load, and mortality during SARS-CoV-2 infections. Patients with severe COVID-19 exhibit also reduced circulating plasmacytoid dendritic cells (pDCs) and low plasma IFNα and IFNλ levels when compared to non-severe COVID-19 patients. In a mouse model of pulmonary HSV-1 infection, treatment with recombinant IL-3 reduces viral load and mortality. Mechanistically, IL-3 increases innate antiviral immunity by promoting the recruitment of circulating pDCs into the airways by stimulating CXCL12 secretion from pulmonary CD123+ epithelial cells, both, in mice and in COVID-19 negative patients exhibiting pulmonary diseases. This study identifies IL-3 as a predictive disease marker for SARS-CoV-2 infections and as a potential therapeutic target for pulmunory viral infections.

Electromyographic response persists after peripheral transection: endorsement of current concepts in recurrent laryngeal nerve monitoring in a porcine model.

BACKGROUND: Recurrent laryngeal nerve palsy is a serious complication of endocrine surgery to the neck. Permanent lesions are still occurring in about one in a hundred, despite standardized surgical approach to the nerve and the availability of recurrent laryngeal nerve monitoring. Intraoperative recurrent laryngeal nerve monitoring is based on the visual or acoustic registration of evoked electromyography of the laryngeal muscles. Primarily, it proves conductivity of the stimulated nerve segment towards the muscle, so that stimulation distal of the lesion should show persistent electromyographic response. METHODS: In a porcine model, an iatrogenic nerve lesion of the recurrent laryngeal nerve was set. Subsequently, the proximal and distal dissected nerve portion was stimulated and the evoked electromyographic response of the laryngeal muscles was recorded by needle and laryngeal surface electrodes. RESULTS: As expected, no signal was obtained from the proximal segment. Meanwhile, the distal segment showed unchanged amplitude of the electrophysiological response for the observation period of more than 1 h. CONCLUSION: This result demonstrated a remarkable pitfall for the neuromuscular monitoring at the recurrent laryngeal nerve: In the human surgical setting, this might have resulted in the false assumption of an anatomical intact nerve. The persistence of distal electromyographic conduction strengthens the proposal to stimulate the vagal nerve as the proximal portion of the nerve as a part of a systematic protocol.

Comparison of Glidescope® Go™, King Vision™, Dahlhausen VL, I­View™ and Macintosh laryngoscope use during difficult airway management simulation by experienced and inexperienced emergency medical staff: A randomized crossover manikin study.

BACKGROUND: In pre-hospital emergency care, video laryngoscopes (VLs) with disposable blades are preferably used due to hygienic reasons. However, there is limited existing data on the use of VLs with disposable blades by emergency medical staff. Therefore, the aim of this study was to compare the efficacy of four different VLs with disposable blades and the conventional standard Macintosh laryngoscope, when used by anesthetists with extensive previous experience and paramedics with little previous experience in endotracheal intubation (ETI) in a simulated difficult airway. METHODS: Fifty-eight anesthetists and fifty-four paramedics participated in our randomized crossover manikin trial. Each performed ETI with the new Glidescope® Go™, the Dahlhausen VL, the King Vision™, the I-View™ and the Macintosh laryngoscope. "Time to intubate" was the primary endpoint. Secondary endpoints were "time to vocal cords", "time to ventilate", overall success rate, number of intubation attempts and optimization maneuvers, Cormack-Lehane score, severity of dental compression and subjective impressions. RESULTS: The Glidescope® Go™, the Dahlhausen VL and the King Vision™ provided superior intubation conditions in both groups without affecting the number of intubation attempts or the time required for successful intubation. When used by anesthetists with extensive experience in ETI, the use of VLs did not affect the overall success rate. In the hands of paramedics with little previous experience in ETI, the failure rate with the Macintosh laryngoscope (14.8%) decreased to 3.7% using the Glidescope® Go™ and the Dahlhausen VL. Despite the advantages of hyperangulated video laryngoscopes, the I-View™ performed worst. CONCLUSIONS: VLs with hyperangulated blades facilitated ETI in both groups and decreased the failure rate by an absolute 11.1% when used by paramedics with little previous experience in ETI. Our results therefore suggest that hyperangulated VLs could be beneficial and might be the method of choice in comparable settings, especially for emergency medical staff with less experience in ETI.