[Measurement of the depth of anaesthesia]

Application of Advanced Technologies-Nanotechnology, Genomics Technology, and 3D Printing Technology-In Precision Anesthesia: A Comprehensive Narrative Review

There has been increasing interest and rapid developments in precision medicine, which is a new medical concept and model based on individualized medicine with the joint application of genomics, bioinformatics engineering, and big data science. By applying numerous emerging medical frontier technologies, precision medicine could allow individualized and precise treatment for specific diseases and patients. This article reviews the application and progress of advanced technologies in the anesthesiology field, in which nanotechnology and genomics can provide more personalized anesthesia protocols, while 3D printing can yield more patient-friendly anesthesia supplies and technical training materials to improve the accuracy and efficiency of decision-making in anesthesiology. The objective of this manuscript is to analyze the recent scientific evidence on the application of nanotechnology in anesthesiology. It specifically focuses on nanomedicine, precision medicine, and clinical anesthesia. In addition, it also includes genomics and 3D printing. By studying the current research and advancements in these advanced technologies, this review aims to provide a deeper understanding of the potential impact of these advanced technologies on improving anesthesia techniques, personalized pain management, and advancing precision medicine in the field of anesthesia.

Comparison of Effects of Stress and Midazolam on Retrograde and Anterograde Amnesia in Patients Undergoing General Anesthesia

Background

The identification of different factors affecting anesthesia and physiological changes during anesthesia can be effective in improving the quality of anesthesia. Midazolam is a benzodiazepine that has been used for many years for sedation under anesthesia. Stress is also an important factor affecting memory and other physiological changes, such as blood pressure and heart rate.

Objectives

his study aimed to investigate the effects of stress on retrograde and anterograde amnesia among patients undergoing general anesthesia.

Methods

This multi-center, parallel, stratified, randomized controlled trial was performed on patients undergoing non-emergency abdominal laparotomy. The patients were divided into high- and low-stress groups according to the Amsterdam Preoperative Anxiety and Information Scale. Then, both groups were randomly divided into three subgroups receiving 0, 0.02, or 0.04 mg/kg of midazolam. Recall cards were shown to patients at 4 minutes, 2 minutes, and immediately before injection to determine retrograde amnesia and at 2 minutes, 4 minutes, and 6 minutes after injection to determine anterograde amnesia. Hemodynamic changes were recorded during intubation. The chi-square and multiple regression tests were used to analyze the data.

Results

Midazolam injection was associated with the development of anterograde amnesia in all groups (P < 0.05); however, it had no effect on the development of retrograde amnesia (P < 0.05). Midazolam could decrease the systolic and diastolic blood pressure and heart rate during intubation (P < 0.05). Stress also caused retrograde amnesia in patients (P < 0.05); nevertheless, it had no effect on anterograde amnesia (P > 0.05). Stress and midazolam injection could not affect the oxygen levels during intubation.

Conclusions

The results showed that midazolam injection could induce anterograde amnesia, hypotension, and heart rate; nonetheless, it had no effect on retrograde amnesia. Stress was associated with retrograde amnesia and increased heart rate; however, it was not associated with anterograde amnesia.

Effects of isoflurane, remifentanil and dexmedetomidine on selected EEG parameters derived from a Narcotrend Monitor before and after nociceptive stimulation at different MAC multiples in cats

Background

The aim of this prospective and complete cross-over study was to evaluate the effects of isoflurane, remifentanil and dexmedetomidine on EEG parameters derived from the Narcotrend® Monitor before and after nociceptive stimulation at different isoflurane MAC (minimal alveolar concentration) multiples. Seven adult European Domestic Short Hair cats were used. Each cat went through 3 experimental treatments. Group I received isoflurane, group IR received isoflurane and a constant rate infusion (CRI) of remifentanil (18 μg/kg/h IV), and group ID received isoflurane and a CRI of dexmedetomidine (3 μg/kg/h IV). The isoflurane MAC in each group was determined via supramaximal electrical stimulation. The EEG parameters were derived by a Narcotrend Monitor at specific time points before and after nociceptive stimulation at 0.75, 1.0 and 1.5 MAC.

The depth of anaesthesia was also assessed by a clinical score.

Results

The mean MAC sparing effects in group IR and group ID were 9.8 and 55.2%, respectively. The best correlation of EEG and MAC multiples was found for the Narcotrend Index (NI) in group I (r = − 0.67). The NI was also able to differentiate between 0.75 MAC and 1.5 MAC in group IR. Spectral edge frequency had a lower correlation with MAC multiples in group I (r = − 0.62) but was able to differentiate between 0.75 MAC and 1.5 MAC in groups I and IR, and between 1.0 MAC and 1.5 MAC in group IR. Narcotrend Index, SEF 95 and MF increased significantly after nociceptive stimulation at 1.0 MAC in group I, and SEF 95 increased significantly at 0.75 MAC in group ID. The clinical score correlated closer than any of the EEG parameters with MAC in all groups, with highest correlation values in group I (r = − 0.89). Noxious stimulation led to a significant increase of the clinical score at 0.75 MAC and 1.0 MAC in group I.

Conclusions

The EEG parameters derived from the Narcotrend Monitor show correlation to isoflurane MAC multiples in cats, but the anaesthetic protocol and especially the addition of dexmedetomidine have great influence on the reliability. The Narcotrend Monitor can be used as an additional tool to assess anesthetic depth in cats.

[Undesired awareness phenomena during general anesthesia: Evidence-based state of knowledge, current discussions and strategies for prevention and management]

Patient awareness during general anesthesia and the later recall of what happened during surgery can be experienced by patients as horrifying events that leave lasting mental trauma in the form of posttraumatic stress syndrome (PTSS). Awareness is related to a temporary insufficient depth of anesthesia. This phenomenon has been discussed for more than 20 years. According to randomized controlled studies, in the absence of risk factors awareness phenomena occur in 1-2 per 1000 operations involving general anesthesia (0.1-0.2%) and are classified as occasionally occurring critical events. An astonishing twist occurred elicited by the recent data from the 5th National Audit Project from Great Britain (NAP5) published in the British Journal of Anaesthesia and in Anaesthesia. The NAP5 evaluated patient reports of accidental awareness during general anesthesia (AAGA) in a multicenter manner in more than 2.7 million cases and indicated incidences of awareness of only 1:19,600, a frequency 20 times less than previously reported. These results gave rise to some controversy. It seems likely that, due to the absence of structured interviews, the NAP5 data only demonstrated the tip of the iceberg and may have vastly underestimated the real incidence of intraoperative awareness. The present overview summarizes the current knowledge about awareness. Furthermore, it addresses the question whether the awareness problem has been overestimated by evidence-based criteria or underestimated by the results of the NAP5. The responsibility for sufficient anesthesia in the clinical routine requires knowledge of awareness risks and potential sequelae. A formal recommendation from the German Society of Anesthesia and Intensive Care Medicine (DGAI) concerning awareness is not yet available; however, the recognition of evidence-based strategies in the management of anesthesia may minimize the occurrence of awareness and its sequelae.

Computer-based diagnostic expert systems in rheumatology: where do we stand in 2014?

Background. The early detection of rheumatic diseases and the treatment to target have become of utmost importance to control the disease and improve its prognosis. However, establishing a diagnosis in early stages is challenging as many diseases initially present with similar symptoms and signs. Expert systems are computer programs designed to support the human decision making and have been developed in almost every field of medicine. Methods. This review focuses on the developments in the field of rheumatology to give a comprehensive insight. Medline, Embase, and Cochrane Library were searched. Results. Reports of 25 expert systems with different design and field of application were found. The performance of 19 of the identified expert systems was evaluated. The proportion of correctly diagnosed cases was between 43.1 and 99.9%. Sensitivity and specificity ranged from 62 to 100 and 88 to 98%, respectively. Conclusions. Promising diagnostic expert systems with moderate to excellent performance were identified. The validation process was in general underappreciated. None of the systems, however, seemed to have succeeded in daily practice. This review identifies optimal characteristics to increase the survival rate of expert systems and may serve as valuable information for future developments in the field.

Awareness under general anesthesia

BACKGROUND

Awareness while under general anesthesia, and the later recall of what happened during surgery, can be experienced by patients as horrific events that leave lasting mental trauma behind. Patients may have both auditory and tactile perception, potentially accompanied by feelings of helplessness, inability to move, pain, and panic ranging to an acute fear of death. For some patients, the experience of awareness under anesthesia has no sequelae; for others, however, it can lead to the development of post-traumatic stress disorder, consisting of complex psychopathological phenomena such as anxiety, insomnia, nightmares, irritability, and depression possibly leading to suicidality.

METHODS

The literature on the subject was selectively reviewed.

RESULTS

In the absence of risk factors awareness phenomena occur in one to two per 1000 operations under general anesthesia (0.1% to 0.2%) and are thus classed as an occasionally occurring critical event. In children, the risk of such phenomena occurring is 8 to 10 times higher. These phenomena are due to an inadequate depth of anesthesia with incomplete unconsciousness. They can be promoted by a number of risk factors that are either patient-related (ASA class III or above, medication abuse), surgery-related (Caesarean section, emergency procedures, surgery at night), or anesthesia-related (anesthesia without benzodiazepines, use of muscle relaxants).

CONCLUSION

Strategies for avoiding awareness phenomena under anesthesia include the training of staff to know about the problem and, specifically, the use of benzodiazepines, the avoidance of muscle relaxants if possible, and shielding the patient from excessive noise. EEG monitoring is effective but provides no guarantee against awareness. If awareness under anesthesia occurs despite these measures, the patient must be given expert, interdisciplinary treatment as soon after the event as possible in order to minimize its potential sequelae.

Monitoring the depth of anaesthesia

One of the current challenges in medicine is monitoring the patients’ depth of general anaesthesia (DGA). Accurate assessment of the depth of anaesthesia contributes to tailoring drug administration to the individual patient, thus preventing awareness or excessive anaesthetic depth and improving patients’ outcomes. In the past decade, there has been a significant increase in the number of studies on the development, comparison and validation of commercial devices that estimate the DGA by analyzing electrical activity of the brain (i.e., evoked potentials or brain waves). In this paper we review the most frequently used sensors and mathematical methods for monitoring the DGA, their validation in clinical practice and discuss the central question of whether these approaches can, compared to other conventional methods, reduce the risk of patient awareness during surgical procedures.

Recovery index, attentiveness and state of memory after xenon or isoflurane anaesthesia: a randomized controlled trial

Background

Performance of patients immediately after anaesthesia is an area of special interest and so a clinical trial was conducted to compare Xenon with Isoflurane anaesthesia. In order to assess the early cognitive recovery the syndrome short test (SST) according to Erzigkeit (Geromed GmbH) was applied.

Methods

ASA I and II patients undergoing long and short surgical interventions were randomised to receive either general anaesthesia with Xenon or Isoflurane. The primary endpoint was the validated SST which covering memory disturbances and attentiveness. The test was used on the day prior to intervention, one and three hours post extubation. The secondary endpoint was the recovery index (RI) measured after the end of the inhalation of Xenon or Isoflurane. In addition the Aldrete score was evaluated up to 180 min. On the first post-operative day the patients rated the quality of the anaesthetic using a scoring system from 1-6.

Results

The demographics of the groups were similar. The sum score of the SST delivered a clear trend one hour post extubation and a statistically significant superiority for Xenon three hours post extubation (p < 0.01). The RI likewise revealed a statistically significant superiority of Xenon 5 minutes post extubation (p < 0.01). The Aldrete score was significantly higher for 45 min. The scoring system results were also better after Xenon anaesthesia (p < 0.001).

Conclusions

The results show that recovery from anaesthesia and the early return of post-operative cognitive functions are significantly better after Xenon anaesthesia compared to Isoflurane. The results of the RI for Xenon are similar with the previously published results.

Trial Registration

The trial was registered with the number ISRCTN01110844 http://www.controlled-trials.com/isrctn/pf/01110844.

Effect of tramadol on bispectral index during anesthesia with desflurane

BACKGROUND

This study is aimed to investigate the effect of tramadol on the bispectral index (BIS) during anesthesia with desflurane.

METHODS

One hundred fifty adults, ASA class 1 and 2 patients, scheduled for general anesthesia for elective surgical procedures were included in this study. None of the patients were premedicated and anesthesia was induced with propofol 2 mg/kg and maintained with air-oxygen (FiO2 0.5) and desflurane, adjusted to keep the BIS between from 50 and 60. Forty minutes before completing surgery, the subjects were randomly allocated into 3 groups to receive saline (control group), tramadol 1.5 mg/kg (T1 group) or 3.0 mg/kg (T2 group) intravenously. Hemodynamics and BIS values were then recorded every 5 minutes until completion of the operation, during which time the concentrations of desflurane were not modified.

RESULTS

The mean BIS values after tramadol administration weren't significantly different from the control group throughout the period of observation. No significant changes in the hemodynamics were noted, except systolic and diastolic arterial blood pressure in the T1 and T2 groups significantly increased in the first 5 minutes after the tramadol injection.

CONCLUSIONS

The results indicate that the administration of tramadol while maintaining anesthesia with desflurane, adjusted to keep the BIS between 50 and 60, does not modified BIS values. So, we propose that tramadol can be safely administered as an immediate postoperative analgesia without concern about intra-operative awareness.