Comparison between effect of desflurane/remifentanil and propofol/remifentanil anesthesia on somatosensory evoked potential monitoring during scoliosis surgery-A randomized controlled trial

The capacity of neurological pupil index to predict the absence of somatosensory evoked potentials after cardiac arrest - An observational study

Background

In neurologic prognostication of comatose survivors from cardiac arrest, two independent predictors of poor outcome are the loss of the Pupillary light reflex (PLR) and the loss of the N20 response from Somatosensory Evoked potentials (SSEP). The PLR can be quantitatively assessed by pupillometry. Both tests depend on the midbrain, in which a dysfunction reflects a severe hypoxic injury. We reasoned that a certain level of defective PLR would be predictive of a bilaterally absent SSEP N20 response.

Method

Neurological Pupil index (NPi) from the pupillometry and the SSEP N20 response were registered >48 h after cardiac arrest in comatose survivors. Clinical data were retrospectively analyzed. A receiver operating characteristic curve was used to evaluate the capacity of NPi to predict bilaterally absent SSEP N20 response. An NPi threshold value resulting in <5% false positive rate (FPR) for bilaterally absent N20 response was identified.

Results

From February 2020 to August 2022, we included 54 patients out of which 49 had conclusive pupillometry and SSEP examinations. The NPi threshold value with FPR < 5% was 3.4, yielding 36% sensitivity (95% CI 18-55) and significantly discriminated between respective groups with preserved and bilaterally absent N20 response to SSEP (p-value <0.01).

Conclusion

In this limited cohort, NPi < 3.4 in patients remaining comatose >48 hours after cardiac arrest predicted bilateral loss of the SSEP N20 response with a FPR < 5%. If validated in a larger cohort, an NPi threshold may be clinically applied in settings where SSEP is unavailable.

Clinical characteristics and anaesthetic management of severe scoliosis patients with spinal muscular atrophy: case series

Introduction and importance

There is no expert consensus or guidance on perioperative anaesthesia management for spinal surgery of spinal muscular atrophy (SMA) patients with severe scoliosis (Cobb≧90°). We provide a comprehensive summary of the perioperative characteristics observed in patients with SMA and propose an optimized perioperative management strategy for anaesthesia.

Methods

This study is a retrospective single-centre research. Twenty-six SMA patients with severe scoliosis underwent posterior spinal fusion surgery from September 2019 to September 2022 were enroled. The main outcomes were to show the patients' characteristics in anaesthesia, intra- and post-operative periods.

Outcomes

Nineteen patients underwent awake transnasal/transairway intubation. The median anaesthesia time of 25 patients treated under total intravenous anaesthesia was 425 min. After operation, the Cobb angle and correction rate in the coronal plane were median 54.0° and 54.4%. The length of mechanical ventilation with endotracheal intubation in ICU was median 17.5 h in 8 patients. The ICU length of stay of postoperative hospital was median 19 days. Postoperative pneumonia developed in nine patients, atelectasis in two patients, and pleural effusion in six patients. All patients did not need special oxygen therapy after discharge.

Conclusion

Multidisciplinary consultation, lung-protective ventilation strategy, appropriate anaesthetic drugs and reasonable blood transfusion scheme and postoperative monitoring were important in anaesthesia, intraoperative and postoperative periods in the patients of severe scoliosis with spinal muscular atrophy.

Long-latency gamma modulation after median nerve stimulation delineates the central sulcus and contrasts the states of consciousness

OBJECTIVE

To evaluate the functional use of sub-band modulations in somatosensory evoked potentials (SSEPs) to discriminate between the primary somatosensory (S1) and motor (M1) areas and contrast the states of consciousness.

METHODS

During routine intraoperative cortical mapping, SSEPs were recorded with electrocorticography (ECoG) grids from the sensorimotor cortex of eight patients in the anesthetized and awake states. We conducted a time-frequency analysis on the SSEP trace to extract the spectral modulations in each state and visualize their spatial topography.

RESULTS

We observed late gamma modulation (60-250 Hz) in all subjects approximately 50 ms after stimulation onset, extending up to 250 ms in each state. The late gamma activity enhancement was predominant in S1 in the awake state, where it discriminated S1 from M1 at a higher accuracy (92 %) than in the anesthetized state (accuracy = 70 %).

CONCLUSIONS

These results showed that sensorimotor mapping does not need to rely on only SSEP phase reversal. The long latency gamma modulation can serve as a biomarker for primary sensorimotor localization and monitor the level of consciousness in neurosurgical practice.

SIGNIFICANCE

While the intraoperative assessment of SSEP phase reversal with ECoG is widely employed to delineate the central sulcus, the median nerve stimulation-induced spatio-spectral patterns can distinctly localize it and distinguish between conscious states.

Updates on Intraoperative Neurophysiology During Surgery for Spinal Dysraphism

Spinal dysraphism is a group of disorders resulting from an embryologic failure of spinal cord development which can lead to a radicular-medullary mechanical stretch that generates vascular compromise and hypoxic-ischemic damage to the nervous structures of the conus-cauda region.Thus, the clinical relevance of the different types of spinal dysraphism is related to the possible neurologic deficits resulting from spinal cord tethering. The clinical presentation is heterogenous: from asymptomatic to very compromised patients. The indications and the time of a detethering surgery are still subject of debate, although there is an agreement on the high standards of treatment that have to be offered by the surgery. Intraoperative neurophysiology (ION) contributes to the safety of tethered cord surgery in reducing the risks of iatrogenic neurological damages.

Neuroanaesthesia: should volatile anaesthetics or total intravenous anaesthesia be used?

The choice of anaesthesia technique for neurosurgical procedures has always been debatable. Despite the well-known effects of volatile anaesthetics on intracranial pressure, these are still widely used. This article explores the advantages and disadvantages of using volatile or total intravenous anaesthesia in patients undergoing neurosurgery.

A device to detect leakage at the patient end of total intravenous anaesthesia

The use of total intravenous anaesthesia (TIVA) is limited by concerns of disconnections of the tubing, resulting in accidental awareness. We designed a sensor device to detect leakages at the patient end and notify the medical personnel, thereby allowing immediate intervention in preventing awareness. For moisture detection, resistive sensing was selected as the working principle. The prototype was in proximity to the tubing from the TIVA pump and the patient's intravenous cannula, and able to detect leakages in all potential leakage sites and activate an alarm. Our device consists of a disposable bandage (sensor), attached to a reusable clamp that is directly coupled to a central module (SparkFun MicroView, a small microcontroller with built-in Organic Light-Emitting Diode (OLED) display). The disposable bandage is wrapped around the possible leakage sites. Crucially, the disposable bandage is integrated with two separate moisture sensing threads. When moisture is present, the central module detects a drop in resistance across the moisture sensing threads and activates a flashing LED and buzzer. We have successfully created a functional leak detection device, comprising a moisture sensing bandage and an audio and visual alert system, to address the problem of undetected TIVA leakages at the patient end.

The effect of low flow anesthesia on hemodynamic and peripheral oxygenation parameters in obesity surgery

Objectives:

To investigate the effects of low-flow anesthesia on hemodynamic parameters and recovery from anesthesia in obese individuals undergoing laparoscopic surgery.

Methods:

This randomized-controlled and prospective study included 44 obese patients who underwent laparoscopic sleeve gastrectomy operation. The patients were randomly allocated into 2 groups as low-flow and high-flow anesthesia. Further, the groups compared in terms of hemodynamic parameters, anesthesia recovery times, operation times, and arterial blood gas parameters.

Results:

The groups were similar with respect to demographic data. Heart rate, peripheral oxygen saturation, arterial blood pressure measurements, end-tidal, and CO₂, lactate levels measurements were similar in both groups during the entire procedure. There was also no statistically significant difference in terms of arterial blood gas parameters or anesthesia recovery periods.

Conclusion:

Low-flow anesthesia in laparoscopic obesity surgery seems to be safer compared to high-flow anesthesia in terms of the adequacy of tissue perfusion, depth of anesthesia, and postoperative recovery.