W Lamadé

Real-time monitoring of the recurrent laryngeal nerve: An observational clinical trial

BACKGROUND A variety of tools has been developed to identify nerve structures and to lower the risk of nerval injury during thyroid surgery. These tools are usually based on intermittent electrophysiological tracing of the nerves, but its use is still associated with permanent recurrent laryngeal nerve (RLN) injury. We are now presenting the results of the implementation of a novel real-time nerve monitoring system, based on a new vagal nerve cuff electrode. METHODS Nineteen consecutive patients scheduled for thyroid surgery (17 with benign, 2 with malignant disease), were enrolled in this observational trial. The flexible cuff electrode was implanted during each operation and atraumatically surrounded the vagal nerve. The evoked potentials were sensed by standard thyroid electrodes. Electrical stimulation and recording were achieved through a multichannel electromyography (EMG) system. The signal analysis was performed in real-time by specially designed software. RESULTS The cuff electrode did not cause any complications during or after the surgery. In all patients, stable and reproducible signals were easily evoked. The mean time required to place the electrode was 6.5 min. The mean overall vagal nerve stimulation time was 65 min. No permanent RLN lesions were detected in any patient. One patient with a postoperative bleeding from a strap muscle vein required a wound revision, which was performed without nerve monitoring. This patient experienced a temporary partial impairment of the left vocal cord. No hypoparathyroidism was observed in any patient postoperatively. CONCLUSIONS The presented technique of real-time continuous RLN monitoring by stimulation of the vagal nerve is feasible, safe, reproducible, and easy to perform. In addition, this new system is compatible with existing equipment and can be used as an add-on with conventional nerve monitoring devices during thyroid surgery.

A new system for continuous recurrent laryngeal nerve monitoring

Existing nerve monitoring devices in thyroid surgery are ‐ except for one ‐ mainly intermittently working nerve identification tools. We present a new vagal electrode which allows true continuous monitoring of the recurrent laryngeal nerve (RLN). The electrode was designed as a tripolar hybrid cuff electrode consisting of polyimide, gold and platinum layers embedded in a flexible silicon cuff which can be opened at the long side for introducing the nerve. It is fully implantable and atraumatic. The evoked potentials are sensed by standard thyroid electrodes. Real‐time signal analysis and audio feedback are achieved by specially designed software. Homogeneous and stable signals were recorded throughout the operations. Thus real‐time computer‐based signal analysis was possible. Evoked potentials reached 300–900 mV. Mean time to place the cuff electrode was 5.5 min. The nerve was stimulated a mean of 63 min (range 55–99 min). No RLN lesions were detected postoperatively. The new vagal electrode was easy to handle and led to stable and reproducible signals. The stimulation current could be kept extremely low due to the special geometry of the electrode. It offers the possibility for uninterrupted, continuous laryngeal nerve monitoring in thyroid surgery. In an ongoing clinical trial its compatibility as an add‐on for existing nerve monitoring devices is being tested.

Impact of continuous intraoperative neuromonitoring on autonomic nervous system during thyroid surgery

Continuous intraoperative neuromonitoring (CIONM) via vagal nerve stimulation (VNS) is a new option for recurrent laryngeal nerve (RLN) protection during thyroid surgery. The aim of this study was to evaluate the safety of VNS for CIONM and to assess its effects on the autonomic nervous system (ANS) through analyzing heart rate variability (HRV).

Safety analysis of vagal nerve stimulation for continuous nerve monitoring during thyroid surgery.

Intraoperative neuromonitoring (IONM) facilitates recurrent laryngeal nerve (RLN) identification, but various studies affirm virtually unchanged postoperative RLN palsy rates. Several authors meanwhile suggest continuous intraoperative neuromonitoring (CIONM) via vagal nerve stimulation (VNS) to improve RLN protection. However, knowledge of side effects of electrical VNS derives mainly from its therapeutic applications in the fields of neurology and psychiatry. The presented study was conducted to further evaluate the safety of CIONM and identify possible VNS related side effects.

Auditory support for resection guidance in navigated liver surgery.

An alternative mode of interaction with navigation systems for open liver surgery was requested. Surgeons who use such systems are impeded by having to constantly switch between viewing the navigation system screen and the patient during an operation.

New backstrap vagus electrode for continuous intraoperative neuromonitoring in thyroid surgery.

Introduction. Continuous intraoperative neuromonitoring (CIONM) via vagal nerve stimulation allows real-time surveillance of the recurrent laryngeal nerve during thyroid surgery. However, for effective CIONM, subtle changes in recurrent laryngeal nerve conductivity have to be detected. A newly developed stimulation electrode that provides stable nerve stimulation and safe application is presented. Methods. For electrode validation, current distribution was simulated with the finite element method. Mechanical characteristics were assessed through bench testing. Clinical evaluation was initiated with 11 thyroid surgeries. Results. Experimental and clinical results led to the development of a tripolar gold/polyimide electrode mounted onto a backstrap-shaped silicone body. It facilitated rapid electrode implantation and extraction (median implantation time 4 ± 19 seconds). Peak extraction force was 570 mN. Median supramaximal stimulation currents were 2.00 ± 0.95 mA and resulted in reliable electromyogram responses (median 3.1 ± 3.0 mV). No intraoperative electrode dislocations occurred, and no postoperative nerve palsy was observed. Conclusion. The new backstrap vagal stimulation electrode meets the requirements for reliable CIONM.

Virtuelle Operationsplanung: Aktueller Stand und Perspektiven

Bereits heute sind schon Software-Programme für die 3D-Analyse und die Therapieplanung parenchymatöser Organe, insbesondere der Leber, für den klinischen Einsatz verfügbar und werden bereits im OP eingesetzt. Die Aufarbeitung der CT-Datensätze mit Segmentierung der Organstrukturen ist allerdings sehr zeit- und personalaufwändig. Die computergenerierten Resektionsvorschläge werden bereits erfolgreich in den OP-Situs übertragen. Dieser Übertragungsschritt soll in Zukunft durch eine Echtzeit-OP-Navigation erfolgen. Die Mehrzahl der Navigationsprojekte stützen sich auf intraoperativen 2D- und 3D-Ultraschall sowie auf optische Registrierungsverfahren. Elektromagnetische Registrierungssensoren werden nur vereinzelt erprobt, da sie sehr störanfällig auf Metallgegenstände reagieren. Wenn ein Registrierungsprozess abgeschlossen ist, gelten die Daten nur so lange, wie das Organ nicht bewegt wird. Im Falle von nichtrigiden Organen wie der Leber muss daher ein Daten-Update in Echtzeit und in kurzen Zeitabständen erfolgen. Ein solches System, das eine Navigation über einen längeren Zeitraum sicherstellt, ist zur Zeit nicht verfügbar. Die Validierung der Planungsdaten existiert bisher nur in Ansätzen. Die Ergonomie, d. h. die Verfügbarkeit der Daten in intuitiv erfassbarer und manipulierbarer Weise, muss noch erheblich verbessert werden. Die Zukunft gehört möglicherweise einem intelligenten Skalpell, das seine Dissektionsaktivität herabsetzt, wenn der geplante Resektionspfad verlassen wird. Die Endverantwortung der Operation wird jedoch auch in Zukunft beim Chirurgen verbleiben.

Prolonged capnoperitoneum does not cause postoperative ileus in pigs: Safety of prolonged capnoperitoneum

Abstract Introduction: Operative time is an accepted risk factor for the development of postoperative ileus (POI). Innovative surgical procedures such as robotic surgery and natural orifice transluminal endoscopic surgery (NOTES) will be associated with longer operative times. Although intraabdominal manipulation is a major factor for POI the impact of prolonged capnoperitoneum on postoperative gastrointestinal transit time (GIT-TT) has rarely been studied. Material and methods: IRB approved survival pilot study to assess postoperative GIT-TT using fecal collection and chromium-oxide (Cr2O3) labeling in pigs. Twelve female pigs were randomly assigned to three groups of four animals each. Group A received eight hours anesthesia and pressure-controlled high flow capnoperitoneum (15 mmHg), group B eight hours of anesthesia only and group C no intervention. No intraoperative manipulation. The pilot study was terminated after eight days. Results: None of the animals developed POI. In Group A one animal died after eight hours of general anesthesia. No differences in postoperative fecal output, Cr2O3 excretion rate or weight gain were found. Conclusion: This study is the first to investigate eight hours of capnoperitoneum in a survival model. GIT-TT is not affected by prolonged capnoperitoneum in pigs. No POI occurred with prolonged capnoperitoneum. Prolonged capnoperitoneum is safe regarding postoperative gastrointestinal function in innovative surgical procedures.