Effect of the relative position of electrode and stellate ganglion during thermal radiofrequency ablation: a simulation study

[EN] Purpose Stellate ganglion (SG) block by thermal radiofrequency ablation (RFA) is frequently conducted as a therapeutic intervention for sympathetic-maintained and neuropathic pain syndromes. RFA's partial lack of effectiveness could be partly due to the ablation zone (AZ) not completely covering the SG section and therefore preventing the 'cutting' of the afferent pathways. Our objective was to build a theoretical model to conduct computer simulations to assess the effect of the electrode position relative to the SG. Methods A three-dimensional model was built including the SG and adjacent tissues (vertebrae C7-T1-T2, trachea, carotid artery and vertebral artery). RFA (90-s, 80 degrees C) was simulated considering a 22 G-5 mm electrode. The AZ was computed using the 50 degrees C isotherm. Results An electrode displacement of 2 mm in any direction from the optimal position (centered on the SG) meant that the AZ did not fully cover the SG section. Likewise, SG size considerably affected the RFA effectiveness since the AZ fully covered the section of small but not large SGs. Conclusions The findings suggest that the currently used SG RFA settings (i.e., 22 G-5 mm electrode, 90-s, 80 degrees C) may not be appropriate due to their inability to achieve an AZ that fully covers the SG cross section under certain circumstances, such as a large SG and non-optimal positioning of the RF electrode with respect to the SG center.This work was supported by the Spanish Ministerio de Ciencia, Innovacion y Universidades under the 'Programa Estatal de I+D+i orientada a los retos de la Sociedad', Grant No 'RTI2018-094357-B-C21', the Universidad Nacional Arturo Jauretche - Argentina 'UNAJ Investiga' [80020170100019UJ], and by the 'Agencia Nacional de Promocion Cientifica y Tecnologica de Argentina' [PICT-2016-2303].Irastorza, RM.; Bovaira, M.; García-Vitoria, C.; Muñoz, V.; Berjano, E. (2021). Effect of the relative position of electrode and stellate ganglion during thermal radiofrequency ablation: a simulation study. International Journal of Hyperthermia. 38(1):1502-1511. https://doi.org/10.1080/02656736.2021.1974580S1502151138

Application of machine learning algorithms in thermal images for an automatic classification of lumbar sympathetic blocks

Purpose There are no previous studies developing machine learning algorithms in the classification of lumbar sympathetic blocks (LSBs) performance using infrared thermography data. The objective was to assess the performance of different machine learning algorithms to classify LSBs carried out in patients diagnosed with lower limbs Complex Regional Pain Syndrome as successful or failed based on the evaluation of thermal predictors. Methods 66 LSBs previously performed and classified by the medical team were evaluated in 24 patients. 11 regions of interest on each plantar foot were selected within the thermal images acquired in the clinical setting. From every region of interest, different thermal predictors were extracted and analysed in three different moments (minutes 4, 5, and 6) along with the baseline time (just after the injection of a local anaesthetic around the sympathetic ganglia). Among them, the thermal variation of the ipsilateral foot and the thermal asymmetry variation between feet at each minute assessed and the starting time for each region of interest, were fed into 4 different machine learning classifiers: an Artificial Neuronal Network, K-Nearest Neighbours, Random Forest, and a Support Vector Machine. Results All classifiers presented an accuracy and specificity higher than 70%, sensitivity higher than 67%, and AUC higher than 0.73, and the Artificial Neuronal Network classifier performed the best with a maximum accuracy of 88%, sensitivity of 100%, specificity of 84% and AUC of 0.92, using 3 predictors. Conclusion These results suggest thermal data retrieved from plantar feet combined with a machine learning-based methodology can be an effective tool to automatically classify LSBs performance

Clinical results of infrared thermography as a support tool to optimise the accuracy of lumbar sympathetic blocks in lower limb Complex Regional Pain Syndrome

Clinical results of infrared thermography as a support tool to optimise the accuracy of lumbar sympathetic blocks in lower limb Complex Regional Pain Syndrom

Recomendaciones de prevención y tratamiento de las náuseas y vómitos postoperatorios y/o asociados a las infusiones de opioides

Las náuseas y los vómitos postoperatorios (NVPO) producen malestar e insatisfacción del paciente y aumentan la necesidad de cuidados. La infusión de opiáceos, frecuente como tratamiento analgésico postoperatorio, puede inducir náuseas y/o vómitos (NV). Este trabajo tiene como objetivo el desarrollo de recomendaciones de prevención y tratamiento de ambos problemas. Con este fin se constituyó un Grupo de Trabajo de acuerdo con los estatutos de la Sociedad Española de Anestesiología y Reanimación. Dicho grupo realizó una evaluación crítica de artículos relevantes sobre el manejo de las NV perioperatorios precoces y tardíos tanto en adultos como en niños. Tras varias reuniones y discusión se acordaron las siguientes recomendaciones (resumen): 1. Todos los pacientes sometidos a cirugía deben ser evaluados respecto al riesgo de desarrollar NVPO. Se recomiendan las escalas de Apfel et al. para adultos y de Eberhart et al. para niños, ambas son útiles y fáciles de aplicar; 2. En los adultos con riesgo moderado o alto y en todos los niños se deben adoptar medidas de reducción del riesgo basal; 3. La profilaxis con un fármaco es útil en pacientes de riesgo bajo (Apfel 1 ó Eberhart 1) sometidos a anestesia general. En los demás pacientes se debe realizar profilaxis con 2 o más fármacos y reducir el riesgo basal (abordaje multimodal); 4. Dexametasona, droperidol y ondansetrón (setrones en general) tienen similar eficacia. La elección de fármaco debe tener en consideración factores individuales en cada paciente; 5. El tratamiento de las NVPO establecidas debe hacerse preferentemente con un fármaco diferente al empleado en la profilaxis. El fármaco más efectivo es el ondansetrón; 6. Debe evaluarse la posibilidad de NVPO tras el alta del paciente en cirugía ambulatoria o en la sala de hospitalización en cirugía con ingreso. No existen evidencias suficientes para formular una estrategia de prevención de las NV tardíos; 7. El fármaco de elección en la prevención de las NV asociadas a infusión de opiáceos es droperidol.Postoperative nausea and vomiting (PONV) causes patient discomfort, lowers patient satisfaction, and increases care requirements. Opioid-induced nausea and vomiting (OINV) may also occur if opioids are used to treat postoperative pain. These guidelines aim to provide recommendations for the prevention and treatment of both problems. A working group was established in accordance with the charter of the Sociedad Española de Anestesiología y Reanimación. The group undertook the critical appraisal of articles relevant to the management of PONV and OINV in adults and children early and late in the perioperative period. Discussions led to recommendations, summarized as follows: 1) Risk for PONV should be assessed in all patients undergoing surgery; 2 easy-to-use scales are useful for risk assessment: the Apfel scale for adults and the Eberhart scale for children. 2) Measures to reduce baseline risk should be used for adults at moderate or high risk and all children. 3) Pharmacologic prophylaxis with 1 drug is useful for patients at low risk (Apfel or Eberhart 1) who are to receive general anesthesia; patients with higher levels of risk should receive prophylaxis with 2 or more drugs and baseline risk should be reduced (multimodal approach). 4) Dexamethasone, droperidol, and ondansetron (or other setrons) have similar levels of efficacy; drug choice should be made based on individual patient factors. 5) The drug prescribed for treating PONV should preferably be different from the one used for prophylaxis; ondansetron is the most effective drug for treating PONV. 6) Risk for PONV should be assessed before discharge after outpatient surgery or on the ward for hospitalized patients; there is no evidence that late preventive strategies are effective. 7) The drug of choice for preventing OINV is droperidol