Neuromonitoring in der Kardioanästhesie

Reduction of the acquisition time needed to obtain somatosensory evoked potentials by estimation of the required averaging sweep count by an algorithm

Somatosensory evoked potentials are frequently acquired by stimulation of the median or tibial nerves (mSEPs and tSEPs) for intraoperative monitoring of sensory pathways. Due to their low amplitudes it is common practice to average 200 or more sweeps to discern the evoked potentials from the background EEG. The aim of this study was to investigate if an algorithm designed to determine the lowest sweep count needed to obtain reproducible evoked potentials in each patient significantly reduces the median necessary sweep count to under 200. 30 patients undergoing spinal surgery at the Department of Neurosurgery were included in the study. Beginning with a sweep count of 200 an algorithm was designed to determine the lowest sweep count that yielded reproducible evoked potentials in each patient. By this algorithm the minimal sweep count was determined in 15 patients for mSEPs and in 15 patients for tSEPs. The required sweep count was below 200 in 14 of 15 patients for mSEPs (93.3%) with a mean sweep count of 56 ± 51. For tSEPs the sweep count was below 200 in 11 of 15 patients (73.3%) with a mean sweep count of 106 ± 70 (mean ± SD). The calculated mean time to average the potentials could thereby be reduced from 48.8s to 13.7s for mSEPs and from 48.8s to 25.9s for tSEPs. The proposed algorithm allowed sweep count and acquisition time reduction in roughly 90% of all patients for mSEPs and in 70% of all patients for tSEPs.

[Anesthesia for aortic valve stenosis : Anesthesiological management of patients with aortic valve stenosis during noncardiac surgery]

Aortic valve stenosis is a common condition that requires an anesthesiologist's in-depth knowledge of the pathophysiology, diagnostics and perioperative features of the disease. A newly diagnosed aortic valve stenosis is often initially identified from the anamnesis (dyspnea, syncope, angina pectoris) or a suspicious auscultation finding during the anesthesiologist's preoperative assessment. Interdisciplinary collaboration is essential to ensure the optimal management of these patients in the perioperative setting. An accurate anamnesis and examination during the preoperative assessment are crucial to select the most suitable anesthetic approach. Additionally, a precise understanding of the hemodynamic peculiarities associated with aortic valve stenosis is necessary. After a short summary of the overall pathophysiology of aortic valve stenosis, this review article focuses on the specific anesthetic considerations, risk factors for complications, and the perioperative management for noncardiac surgery in patients with aortic valve stenosis.

Extended neuromonitoring in aortic arch surgery : A case series

BACKGROUND

Aortic arch repair for aortic dissection is still associated with a high mortality rate. Providing adequate means of neuromonitoring to guide cerebral hemodynamics is advantageous, especially during selective anterior cerebral perfusion (SACP).

OBJECTIVE

We aimed to investigate an easy multimodal neuromonitoring set-up consisting of processed electroencephalography (EEG), near infrared spectroscopy (NIRS), and transcranial doppler sonography (TCD).

MATERIAL AND METHODS

We collected intraoperative data from six patients undergoing surgery for aortic dissection. In addition to standard hemodynamic monitoring, patients underwent continuous bilateral NIRS, processed EEG with bispectral index (BIS), and intermittent transcranial doppler sonography of the medial cerebral artery (MCA) with a standard B‑mode ultrasound device. Doppler measurements were taken bilaterally before cardiopulmonary bypass (CPB), during CPB, and during SACP at regular intervals.

RESULTS

Of the patients four survived without neurological deficits while two suffered fatal outcomes. Of the survivors two suffered from transient postoperative delirium. Multimodal monitoring led to a change in CPB flow or cannula repositioning in three patients. Left-sided mean flow velocities of the MCA decreased during SACP, as did BIS values.

CONCLUSION

Monitoring consisting of BIS, NIRS, and TCD may have an impact on hemodynamic management in aortic arch operations.

Effects of a dual-filter-based cerebral embolic protection device in transcatheter aortic valve replacement on cerebral oxygen saturation: A prospective pilot study

PURPOSE

The Sentinel Cerebral Protection System (Sentinel-CPS) is increasingly used in transcatheter aortic valve replacement (TAVR). However, the impact of inserting the Sentinel-CPS inside the brain-supplying arteries on cerebral perfusion and oxygenation is unknown.

METHODS

Twenty patients undergoing transfemoral TAVR with (n = 10) and without (n = 10) cerebral embolic protection using the Sentinel-CPS were prospectively observed. All patients received conscious sedation and cerebral oxygen saturation (rSO₂ ) was continuously measured with near-infrared spectroscopy (NIRS). The cumulative perioperative cerebral desaturation was calculated for each patient by multiplying rSO₂ below an individualized desaturation threshold by time. In addition, rSO₂ values at the time of Sentinel-CPS insertion, filter positioning, and device retraction were analyzed.

RESULTS

There was no significant difference in cumulative cerebral desaturation in patients with Sentinel-CPS (median [IQR]) (0 [0/81] s%) and without (median [IQR]) (0 [0/23] s%), p = .762. A total of 6 patients (33.3%) experienced a perioperative decrease in rSO₂ below the individualized desaturation threshold (n = 3 with Sentinel-CPS, n = 3 without Sentinel-CPS; p = 1.000). Cerebral desaturation was detected during valve deployment (n = 5) and after postdilatation (n = 1). No desaturation events occurred during Sentinel-CPS insertion, filter positioning, or retraction.

CONCLUSION

Our pilot study revealed no difference in cumulative perioperative cerebral desaturation between TAVR with and without Sentinel-CPS. Catheter- and filter-based manipulations in the brain-supplying arteries for Sentinel-CPS application were not associated with a decrease of cerebral perfusion and oxygenation.

[Anesthesiological implications of minimally invasive valve interventions : Transcatheter aortic valve implantation, clip reconstruction on the mitral and tricuspid valve]

Catheter-guided interventional implantation of cardiac valves is one of the main developments in cardiology over the past 15 years. It is characterized by a close interdisciplinary cooperation in the heart team (H-team), which consists of cardiac anesthesiologists, cardiologists and heart surgeons. This co-responsibility for anesthesia, which is demanded by the legislator (Federal Joint Committee, G‑BA, July 2015), includes not only qualified training for the cardiac anesthesiologist, including transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) but also several years of experience in cardiac anesthesia and correlates with the recommendations of the German Society for Anaesthesiology and Intensive Care Medicine. In accompaniment with the demographic development, the number of heart valve diseases increases with age. More than 50% of all heart operations are performed on patients over the age of 70 years and nearly 20% on patients over the age of 80 years. Minimally invasive procedures are outstanding opportunities for patients who were initially classified as inoperable. Therefore, anesthesiologists must have precise knowledge of the possible complications related to the procedure itself. Additionally, it challenges the anesthesiologist with unconventional situations in the care of older patients who are exposed to a higher risk. The aforementioned risks are organic functional restrictions, increasing number of comorbidities and more severe exposure due to malnutrition and frailty; however, monitoring methods are also being developed aiming for patient-specific anesthesia management and analgesia treatment. This article discusses the interventional procedures of heart valvular diseases as well as the hemodynamic changes associated with the procedures from the anesthesiologist's point of view. To present examples, we have selected transcatheter aortic valve replacement (TAVR) and the interventional procedure of mitral and tricuspid valve insufficiency called MitraClip and TricaClip. A thorough examination of the procedural risk rate shows that despite minimizing the surgical intervention by miniaturizing the devices, the presence of an experienced cardiac anesthesiologist is obligatory.

Intraoperative reduction of vasopressors using processed electroencephalographic monitoring in patients undergoing elective cardiac surgery: a randomized clinical trial

Intraoperative vasopressor and fluid application are common strategies against hypotension. Use of processed electroencephalographic monitoring (pEEG) may reduce vasopressor application, a known risk factor for organ dysfunction, in elective cardiac surgery patients. Randomized single-centre clinical trial at Jena University Hospital. Adult patients operated on cardiopulmonary bypass or off-pump coronary artery bypass grafting were randomised to receive anesthesia with visible or blinded pEEG using Narcotrend™. In blinded-Narcotrend (NT) depth of anesthesia was extrapolated from clinical signs, hemodynamic response and anesthetic concentration, supplemented by target indices between 37 and 64 in the visible-NT group. Intraoperative norepinephrine requirement (primary endpoint), fluid balance, extubation time, delirium occurrence and adverse events were evaluated. Patients of the intent-to-treat population (visible-NT: n = 123, blinded-NT: n = 122) had similar patient and procedural characteristics. Adjusted for type of surgery intraoperative Norepinephrine application was significantly reduced in visible-NT (n = 120, robust mean of cumulative dose 4.71 µg/kg bodyweight) compared to blinded-NT patients (n = 119, 6.14 µg/kg bodyweight) (adjusted robust mean difference 1.71 (95% CI 0.33-3.10) µg/kg bodyweight). Although reduction in patients operated on cardiopulmonary bypass was higher the interaction was not significant in post-hoc subgroup analysis. Intraoperative fluid balance was similar among both groups and strata. Extubation time was non-significantly lower in visible than in blinded-NT group. Overall postoperative delirium risk was 16.4% without differences among the groups. Adverse events-sudden movement/coughing, perspiration or hypertension-occurred more often with visible-NT, while one blinded-NT patient experienced intraoperative awareness. Titration of depth of anesthesia in elective cardiac surgery patients using pEEG allows to reduce application of norepinephrine.