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.

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.

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.

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.

Combined recurrent laryngeal nerve monitoring and one-lung ventilation using the EZ-Blocker and an electromyographic endotracheal tube.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

The EZ-blocker for one-lung ventilation in patients undergoing thoracic surgery: clinical applications and experience in 100 cases in a routine clinical setting.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Can we rely on out-of-hospital blood samples? A prospective interventional study on the pre-analytical stability of blood samples under prehospital emergency medicine conditions.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. DISCUSSION: 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. CONCLUSION: We conclude the validity of blood samples from a prehospital environment.

Hydroxyethyl starch solution for extracorporeal tissue perfusion.

In the field of free flap transfer in reconstructive surgery, the trans- or replanted tissue always undergoes cell damage during ischemia to a more or less strong extent. In previous studies we already showed that conserving muscle transplants by means of extracorporeal perfusion over a period of 6 hours by using a crystalloid solution for perfusion. However, we observed significant edema formation. In this study we aimed at reducing the edema formation by using an iso-oncotic colloid as perfusion solution. This way we wanted to evaluate a possible new application of hydroxyl-ethyl starch in an extracorporeal setup to exploit potential benefits of the colloid.Examined parameters include the muscles' functionality with external field stimulation, histological examination and edema formation. Perfused muscles showed a statistically significant higher ability to exert force compared to nonperfused ones. These findings can be confirmed using Annexin V as marker for cell damage, as perfusion of muscle tissue limits damage significantly compared to nonperfused tissue. Substituting the electrolyte perfusion solution with a colloidal one shows the tendency to reduce the edema formation however without statistical significance.

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.

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.

Immunohistochemical evaluation after ex vivo perfusion of rectus abdominis muscle flaps in a porcine model.

BACKGROUND: The purpose of this study was to investigate whether and how the extracorporal perfusion of muscle flaps with a miniaturized perfusion system could change the expression of the proapoptotic protein caspase 3 and of the ischemia-sensitive protein hypoxia-inducible factor (HIF)-1α as a first step toward the development of a clinically reliable tool for circumventing ischemia problems in free muscle flap transfer. METHODS: In this study, 25 porcine rectus abdominis muscles were used and assigned to five different groups. In the baseline group (group I), the muscle flap remained in situ; in groups II and III, the muscle flap was harvested and remained ex vivo without or with subsequent single-shot heparinized flush; and in groups IV and V, the flaps were perfused with either heparinized autologous whole blood or crystalloid fluid (Jonosteril), using a miniaturized perfusion system without Exogen oxygenation. Muscle samples were taken for immunohistochemical evaluation. The proportion of positive cells for HIF-1α and caspase 3 was compared for each group (groups II through V) to the baseline group (group I). RESULTS: The expression of HIF-1α and caspase 3 was increased in both groups without perfusion and was low during in vivo perfusion and extracorporal perfusion with crystalloid fluid. Heparinized autologous whole blood perfusion shows no protective effect, in contrast to the crystalloid fluid. CONCLUSIONS: The data of this study indicate that the extracorporal perfusion of muscle flaps with crystalloid fluid is a possible protective strategy against ischemia. Autologous heparinized whole blood seems to have no additional protective effect in a pure perfusion setting without oxygenation.

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.

Laryngeal morbidity after intubation with or without neuromuscular block in thyroid surgery using recurrent laryngeal nerve monitoring.

OBJECTIVE: The avoidance of neuromuscular blocking agents (NMBA) for endotracheal intubation is associated with a higher incidence of laryngeal discomfort and lesions, but could impair effectiveness of intra operative recurrent laryngeal nerve monitoring (IONM). METHODS: In a retrospective quality assessment study over a period of 30 months, a collective that had been intubated without NMBA was compared with a group, which had received NMBA. Endolaryngeal EMG was accomplished with a MagStim(®)-EMG-electrode. RESULTS: Out of the 127 patients with 224 nerves at risk (NAR; NMBA 102 NAR, no NMBA 122 NAR), more than 90% received a total intravenous anaesthesia with propofol, and 88% had remifentanil. Laryngeal side effects and damage scores did not differ significantly. CONCLUSIONS: In this special setting of IONM and thyroid surgery, avoidance of NMBA for endotracheal intubation seems not to increase the incidence of laryngeal side effects and lesions. If endotracheal intubation without NMBA is required, the authors suggest a standardized approach using induction agents as propofol and remifentanil.

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.

Guided bone regeneration: dynamic procedures versus static shielding in an animal model.

Due to its osteoinductive potential, the periosteum plays a crucial role in the process of neoosteogenesis. Therefore, periosteal elevation can lead to new bone formation in an artificially created space. In this study, we compared dynamic periosteal elevation with static shielding in an animal experiment. Different elevation/shielding heights of 5, 10, and 15 mm were tested with regard to various consolidation periods. Histological analysis, histomorphometry, and microradiography were used to measure the quantity and quality of the newly formed bone. No significant differences regarding bone quantity or quality were found between the two techniques. The cumulative results for the bone regeneration in the space created by distraction/elevation were about 66% in the dynamic and 67% in static procedure. The main advantages of both techniques are minimal invasion and low morbidity. In terms of clinical applications, periosteal elevation could be applied in cranio-maxillofacial surgery, in pre-implant augmentation and in reconstructive surgery.

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.

Dynamic periosteal elevation.

The osteoinductive potential of the periosteum can be stimulated by raising the periosteum using a type of distraction. This was tested and confirmed in an animal experiment in 6 Goettingen minipigs. A titanium mesh was implanted beneath the periosteum and then raised. Bone formed underneath the mesh, with rows of micro-pillars similar to those found after osteodistraction. The main advantages of dynamic periosteal elevation are that invasion and morbidity are minimal. Clinically it might be applicable in craniomaxillofacial surgery, in augmentation before implantation, and in reconstruction of the skull.