Rapid automated classification of anesthetic depth levels using GPU based parallelization of neural networks.

The effect of anesthesia on the patient is referred to as depth of anesthesia. Rapid classification of appropriate depth level of anesthesia is a matter of great importance in surgical operations. Similarly, accelerating classification algorithms is important for the rapid solution of problems in the field of biomedical signal processing. However numerous, time-consuming mathematical operations are required when training and testing stages of the classification algorithms, especially in neural networks. In this study, to accelerate the process, parallel programming and computing platform (Nvidia CUDA) facilitates dramatic increases in computing performance by harnessing the power of the graphics processing unit (GPU) was utilized. The system was employed to detect anesthetic depth level on related electroencephalogram (EEG) data set. This dataset is rather complex and large. Moreover, the achieving more anesthetic levels with rapid response is critical in anesthesia. The proposed parallelization method yielded high accurate classification results in a faster time.

Are females predisposed to complications in head and neck cancer free flap reconstruction?

PURPOSE: To investigate gender and other possible factors affecting the frequency and severity of postoperative complications in head and neck cancer free flap reconstruction. MATERIALS AND METHODS: A prospective longitudinal cohort study was conducted at the Greek Anticancer Institute, St. Savvas Hospital in head and neck cancer free flap reconstruction concerning postoperative complications. We documented the patients' demographic characteristics, social habits, and perioperative factors (ie, duration of general anesthesia), reconstructive techniques, neoadjuvant radiotherapy, and physical status. Initially, univariate statistical analysis was performed to confirm which predictor variables might influence the presence and severity of complications. Next, multivariate statistical analysis was performed using logistical regression and including the factors that were statistically significant on univariate analysis. RESULTS: From 1999 to 2009, we assessed 95 patients who had undergone surgery for head and neck cancer. Of the 95 patients, 24 were women and 71 were men. The patient age range was 20 to 87 years (mean 52, median 55). A total of 55 complications occurred in 49 patients (51.57%). Of the 55 complications, 12 (12.63%) were of major severity, 21 (22.10%) of median severity, and 22 (23.15%) of low severity. The statistical analysis revealed that the factors associated with complications were preoperative radiotherapy, female gender, and operation time. The factors associated with severe complications were female gender and alcohol use. CONCLUSIONS: Multivariate analysis of the data revealed that the factor associated with an increased incidence of postoperative complications was preoperative radiotherapy. Moreover, the variable that remained statistically significant and correlated with an increased incidence and severity of free flap reconstruction complications was female gender. Identifying the etiology of these findings is an intriguing field for additional research.

Pharmacodynamic considerations for moderate and deep sedation.

Moderate and deep sedation can be provided using various classes of drugs, each having unique mechanisms of action. While drugs within a given classification share similar mechanisms and effects, certain classes demonstrate superior efficacy but added concern regarding safety. This continuing education article will highlight essential principles of pharmacodynamics and apply these to drugs commonly used to produce moderate and deep sedation.

Influence of anesthetic drugs and concurrent psychiatric medication on seizure adequacy during electroconvulsive therapy.

OBJECTIVE: Electroconvulsive therapy (ECT) is performed under anesthesia and muscle relaxation. Only well-generalized seizures seem to have the high "adequacy" or "quality" that have been claimed to reflect positive predictive power for the outcome of an ECT course. The induction of well-generalized seizures can be potentially influenced by several variables. One major variable is concurrent medication including anesthetic drugs, since most anesthetic drugs are potent anticonvulsives. We hypothesized a negative influence of anesthetics and benzodiazepines but a positive effect of antidepressants and antipsychotics concurrently applied during ECT on seizure adequacy. METHOD: We included inpatients (n = 41) with a DSM-IV-diagnosed major depressive episode treated with ECT (411 ECT sessions) during a period of 20 months (May 2005 to December 2006) in an open label and noncontrolled study. A repeated measurement regression analysis was performed with 8 seizure adequacy parameters as dependent variables. We indirectly quantified narcotic agent influence with bispectral index monitoring. RESULTS: In contrast to the impact of psychiatric comedication, this measure of "depth of narcosis" prior stimulation turned out to influence most seizure adequacy parameters in a highly significant manner. CONCLUSIONS: Thus, we concluded that the anticonvulsive properties of narcotic agents have much higher influence than concomitant psychotropic medication. Our data support the view that a significant influence of concurrent psychotropic drugs on seizure adequacy markers is missing, especially when directly compared with other confounders like stimulation energy, age, and depth of narcosis. The latter suggests to further prove the idea that lighter anesthesia is indeed an important tool to get patients faster into remission.

Conscious sedation v. monitored anaesthesia care--20 years in the South African context.

Sedation of patients for minor procedures is here to stay. However, it is the responsibility of every physician to be aware of the potential complications associated with the combination of drugs administered and to practise in an environment where no risks are taken and no procedures performed outside the circle of safety. Furthermore, as an anaesthetic service, monitored anaesthesia care (MAC) is clearly distinct from moderate sedation and it is important for patient safety that these differences are recognised and adhered to. In essence, all practitioners must observe the strict distinctions between sedation and MAC to prevent the drift into deeper sedation under inappropriate circumstances.

Resultados del tratamiento conservador de las fracturas de cotilo / Results of the conservative treatment of acetabular fractures

Objetivos. Estudiar la evolución de pacientes con fracturas de cotilo tratadas de forma conservadora. Material y método. Se recogieron de forma consecutiva 37 casos de fracturas de cotilo, tratados de forma conservadora con un seguimiento mínimo de 5 años. Las fracturas se trataron con reposo en cama y tracción seguido de un período de descarga y otro de carga parcial. Los pacientes se valoraron clínica y radiográficamente. El tipo de tratamiento fue evaluado según la tracción empleada, el tiempo de descarga y de carga parcial. Se evaluó el grado de desplazamiento y su relación con la evolución posterior. Resultados. Veinte fracturas no presentaron desplazamiento, 8 un desplazamiento entre 2-5 mm y en 9 casos fue superior a 5 mm. Al final del seguimiento 8 pacientes presentaron dolor, 15 movilidad limitada y 8 signos radiográficos de artrosis. El grado de desplazamiento se correlacionó con el resultado final. Conclusiones. El tratamiento conservador puede ser una indicación en las fracturas de cotilo cuando el estado del paciente, el tipo de fractura o la calidad de hueso no permitan una osteosíntesis (AU)

Purpose. To study the evolution of patients with acetabular fractures treated conservatively Material and methods. A series of 37 consecutive cases treated conservatively was analyzed. The minimum follow-up was 5 years. Fractures were treated with bed rest and traction, which were followed by a non weight-bearing period and a partial weight period. Patients were clinically and radiographically assessed. The different kinds of treatment were evaluated on the basis of the type of traction used, the length of the non weight-bearing period and the duration of the partial weight bearing one. The degree of displacement was also considered, in particular as it related with the patients’ subsequent evolution. Results. Twenty fractures did not undergo any sort of displacement, 8 had a displacement of 2-5 mm, with 9 cases having a displacement higher than a 5 mm. At the end of follow-up, 8 patients experienced pain, 15 limited mobility and 8 had radiographic signs of osteoarthritis. The degree of displacement was correlated with the final result obtained. Conclusions. Conservative treatment can be an appropriate indication for acetabular fractures when the patient’s condition, the type of fracture or bone quality advise against performing an osteosynthetic procedure (AU)

Laryngoplasty with ventriculectomy or ventriculocordectomy in 104 draft horses (1992-2000).

OBJECTIVE: To evaluate efficacy and safety of laryngoplasty with vetriculectomy (VE) or ventriculocordectomy (VCE) for treatment of laryngeal hemiplegia (LH) in draft horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: One hundred four draft horses used for competitive hitch competitions. METHODS: Medical records and postoperative endoscopy for competitive hitch draft horses diagnosed with left LH and treated with laryngoplasty and VE or VCE between January 1992 and December 2000 were reviewed. Follow-up information was obtained from telephone interviews with owners and trainers, and performance scores of 1 to 3 were assigned in which 1 was defined as a horse that was unable to perform (abnormal respiratory noise with or without exercise intolerance), 2 was able to perform but not for its intended use (exercise tolerant but abnormal respiratory noise), and 3 was performing as expected for its intended use (exercise tolerant, no abnormal respiratory noise). RESULTS: One hundred four horses that had 111 laryngoplasty procedures were included. All horses had preoperative performance scores of 1. Follow-up information was available for 79 horses. Improvement in postoperative performance (exercise tolerant, with or without abnormal respiratory noise) was reported in 92% of horses. Respiratory noise was eliminated in 72% (57 horses) of horses. Postoperative performance scores were the following: 3 in 57 (72%) horses, 2 in 16 (20%) horses, and 1 in 6 (8%) horses. There was no significant difference in postoperative performance based on preoperative grade of LH. There was a trend for horses with >/=70% of possible maximal abduction postoperatively to have a performance score of 3. Postanesthetic complications included prolonged recovery (4 horses, 4%) and myopathy or neuropathy (7 horses, 7%). One of these horses was killed because it did stand; triceps myopathy and encephalopathy were confirmed on necropsy. CONCLUSIONS: Laryngoplasty with VE or VCE is an effective and safe procedure for the treatment of LH in the draft horse. Repeat laryngoplasty can be performed successfully, with good performance outcome after laryngoplasty failure. Complications associated with general anesthesia and laryngoplasty in draft horses are higher than reported for light breed horses under similar conditions. CLINICAL RELEVANCE: For LH, laryngoplasty with VCE or VE under general anesthesia is recommended to eliminate abnormal respiratory noise and improve performance in most competitive hitch draft horses.

General anaesthesia: practical recommendations and recent advances.

General anaesthesia has become, thanks to recently developed drugs, monitoring devices and delivery systems, a very well tolerated method of making the great surgical opportunities of the last few years available to all ages of patient. With a balanced and rational use of drug profiles, general anaesthesia allows even frail and very ill patients a margin of tolerability inconceivable just a few years ago. For the vast majority of patients, the risk from the general anaesthetic technique is so small it can be considered negligible. However, the majority of general anaesthetic drugs are both highly potent and very toxic, with many of the volatile agents still having a therapeutic ratio of about 4:1. The anaesthetic staff have to continually upgrade their skills and knowledge to ensure that harm does not result. It is, however, reasonable to offer some practical guidelines from the current literature on when to choose a general anaesthetic technique, either alone or with a regional local anaesthetic method, and when to avoid loss of consciousness. The complications expected from the use of general anaesthesia are reviewed, and the basis for these complications investigated. The currently available drugs and their place in anaesthetic practice are also assessed. Recent developments in the area of total intravenous anaesthesia and monitoring for potential awareness using bispectral analysis suggest that this technique should now be included in the choice of anaesthetic. Recommendations are made on both the selection of the technique, and the appropriate agents for a given group of patients.

Post-tetanic burst count and train-of-four during recovery from vecuronium-induced intense neuromuscular block under different types of anaesthesia.

Recovery of neuromuscular blockade after vecuronium 0.2 mg kg-1 was measured by post-tetanic burst count (PTBC) and train-of-four (TOF) in 120 adult patients anaesthetized by one of four techniques: neuroleptanaesthesia or one minimum alveolar concentration of isoflurane, enflurane, or sevoflurane. Onset of recovery was taken when there was reflex movement in response to carinal stimulation. The time course of recovery measured by burst count was similar for all four types of anaesthesia. Recovery of each of the twitches of the TOF was significantly shorter under neuroleptanaesthesia than under isoflurane, enflurane, or sevoflurane anaesthesia [times to return of T1 were 41.4 +/- 5.4, 51.5 +/- 10.6, 52.2 +/- 10.0, or 55.3 +/- 11.2 min (mean +/- SD). P < 0.05]. The burst count at the onset of reflex movement was less under neuroleptanaesthesia than under isoflurane, enflurane, or sevoflurane anaesthesia (16.3 +/- 4.8, 26.7 +/- 6.7, 27.7 +/- 6.8, 28.0 +/- 8.4, P < 0.05). The ratio of first twitch to control twitch at the onset of reflex movement was the same for all four types of anaesthesia.

Ensuring early discharge following major surgery: orthopedic surgery.

Managed care, critical pathways, and length of stay issues have a major impact on current hospital policy and patient care. In orthopedic surgery, significant strides have been made in improving efficiency, decreasing costs, and reducing length of stay. Use of vertical pathways, especially the first day of admission, the day of surgery, is important for efficient patient care. As anesthesiologists involved in the process, we must be certain that patient care is not compromised in an attempt to save money or achieve early discharge. In many studies, pain management, type of anesthesia, and amount of blood loss are not significant factors in length of hospital stay. These factors must be approached as quality-of-life issues and appropriate decisions made.

[Attempt at a definition of the individual anesthesia level by repetitive pain stimulation: correlation with EEG findings]. / Versuch einer Definition des individuellen Anästhesieniveaus über repetitive Schmerzreizung: Korrelation mit EEG-Befunden.

AIM: Previous studies using EEG for assessment of depth of anaesthesia correlate anaesthetic concentration with the anaesthetic stage. This procedure neglects the well known effect of individual different susceptibility to anaesthetics. Thus, patients receiving similar concentrations of anaesthetics may not necessarily be at the same level of "anaesthetic depth". The aim of this study was to define an interindividual comparable level of anaesthesia by recording the autonomic cardiovascular reaction to a standardised painful stimulus (tetanic stimulus, 80 mA, 100 Hz). METHODS: In 61 patients undergoing orthopaedic surgery general anaesthesia was performed with isoflurane in 66% N2O. Starting from 0.4% isoflurane, endtidal isoflurane concentration was increased in a stepwise manner (0.1% isoflurane) until the patient did not show any relevant cardiovascular reaction (increase of heart rate and/or blood pressure < 10%) after tetanic stimulation of the ulnar nerve. If patients demonstrated no haemodynamic changes at 0.4% isoflurane, the concentration was decreased until a relevant cardiovascular reaction was registered. During each steady state period multichannel EEG was recorded and mean values of power density (median: microV2/Hz) were computed. RESULTS: Comparing EEG-results between both groups exhibiting a cardiovascular reaction (CVR+ , median endtidal Iso: 0.5%) and without reaction (CVR- , median endtidal Iso: 0.6%) an increase in low frequency bands and a significant decrease in high frequencies was found (Wilcoxon-test, p < 0.05). In contrast, comparing EEG-data only in relation to endtidal isoflurane concentration neglecting individual haemodynamic responses, no differences of power density in high frequency bands were detected. CONCLUSION: This method to define individual depth of anaesthesia as described, results in more consistent EEG patterns and may be useful in relating EEG to depth of anaesthesia.

De la neuroleptoanalgesia a la anestesia analgésica

Detalle de la evolución de las técnicas anestésicas, de los componentes fundamentales de la anestesia:analgesia, protección neurovegetativas, hiporosis y relajación muscular. Química y farmacología y efectos adversos de los analgésicos centrales, morfinominéticos, neurolépticos. Asociaciones empleadas y farmacología de los medicamentos utilizados. Métodos de la neuroleptoanalgesia tipo I y II de la anestesia analgésica

De la neuroleptoanalgesia a la anestesia analgésica

Detalle de la evolución de las técnicas anestésicas, de los componentes fundamentales de la anestesia:analgesia, protección neurovegetativas, hiporosis y relajación muscular. Química y farmacología y efectos adversos de los analgésicos centrales, morfinominéticos, neurolépticos. Asociaciones empleadas y farmacología de los medicamentos utilizados. Métodos de la neuroleptoanalgesia tipo I y II de la anestesia analgésica