Development of a New Aggregation Method to Remove Nanoplastics from the Ocean: Proof of Concept Using Mussel Exposure Tests.

The overproduction and mismanagement of plastics has led to the accumulation of these materials in the environment, particularly in the marine ecosystem. Once in the environment, plastics break down and can acquire microscopic or even nanoscopic sizes. Given their sizes, microplastics (MPs) and nanoplastics (NPs) are hard to detect and remove from the aquatic environment, eventually interacting with marine organisms. This research mainly aimed to achieve the aggregation of micro- and nanoplastics (MNPs) to ease their removal from the marine environment. To this end, the size and stability of polystyrene (PS) MNPs were measured in synthetic seawater with the different components of the technology (ionic liquid and chitosan). The MPs were purchased in their plain form, while the NPs displayed amines on their surface (PS NP-NH2). The results showed that this technology promoted a significant aggregation of the PS NP-NH2, whereas, for the PS MPs, no conclusive results were found, indicating that the surface charge plays an essential role in the MNP aggregation process. Moreover, to investigate the toxicological potential of MNPs, a mussel species (M. galloprovincialis) was exposed to different concentrations of MPs and NPs, separately, with and without the technology. In this context, mussels were sampled after 7, 14, and 21 days of exposure, and the gills and digestive glands were collected for analysis of oxidative stress biomarkers and histological observations. In general, the results indicate that MNPs trigger the production of reactive oxygen species (ROS) in mussels and induce oxidative stress, making gills the most affected organ. Yet, when the technology was applied in moderate concentrations, NPs showed adverse effects in mussels. The histological analysis showed no evidence of MNPs in the gill's tissues.

Incidence of postoperative residual neuromuscular blockade - A multicenter, observational study in Portugal (INSPIRE 2).

Background: Although the use of neuromuscular blocking agents (NMBAs) optimizes surgical conditions and facilitates tracheal intubation, it can lead to residual neuromuscular blockade (RNMB), with postoperative complications. This study aimed to assess RNMB incidence and management in Portugal. Methods: Prospective observational study of patients admitted for elective surgery requiring general anesthesia with nondepolarizing NMBAs between July 2018 and July 2019 at 10 Portuguese hospitals. The primary endpoint was the proportion of patients arriving at postanesthesia care unit (PACU) with a TOF ratio <0.9. Results: A total of 366 patients were included, with a median age of 59 years, and 89.1% classified as ASA II or III. Rocuronium was the most used NMBA (99.5%). A total of 96.2% of patients received a reversal agent, 96.6% of which sugammadex and 3.4% neostigmine. Twenty patients displayed a TOF ratio <0.9 at PACU arrival, representing an RNMB incidence of 5.5% (95% CI, 3.1%-7.8%). Only two patients displayed a TOF ratio <0.7. RNMB incidence was 16.7% with neostigmine and 5.3% with sugammadex (P = .114). In patients with intraoperative neuromuscular blockade (NMB) monitoring, RNMB incidence was 5% (95% CI, 2%-8%), which varied significantly according to the type of monitoring (P = .018). Incidence of adverse events was 3.3% (2 severe and 10 moderate). Conclusions: The reported overall incidence of 5.5% is numerically lower than results from similar observational studies. An appropriate pharmacological neuromuscular reversal strategy, guided by quantitative neuromuscular monitoring, has the potential to achieve even better results, converting RNMB from an unusual to a very rare or even inexistent event.

Comparison of two pharmacokinetic-pharmacodynamic models of rocuronium bromide during profound neuromuscular block: analysis of estimated and measured post-tetanic count effect.

BACKGROUND: Profound neuromuscular block (NMB) is important in surgeries where complete immobility is considered essential to improve tracheal intubation and surgical conditions. Rocuronium bromide is a commonly used NMB agent. This work describes a noninvasive approach for estimation of post-tetanic count (PTC) based on two pharmacokinetic (PK) models, the Saldien and the De Haes models. The aim was to investigate the rocuronium bromide PK-pharmacodynamic (PD) relationship in estimating the PTC effect during profound NMB. METHODS: In this prospective, non-randomised, observational study, an induction bolus of rocuronium bromide was administered followed by continuous infusion for maintenance of a PTC of 1-2. measured every 3 min. Measurements were analysed as discrete categorical data and by applying the nonlinear mixed-effect modelling approach. Performance of the selected models was evaluated through simulation model-based diagnostics, further assessing the precision of the parameter estimates and the performance of the models at the individual level. RESULTS: Data from 30 adult patients undergoing elective abdominal or neurosurgical procedures were included. Post-tetanic count response profiles during rocuronium bromide infusion were successfully characterised using the population PD analysis. The models showed a good performance for all PTC categories, albeit with a moderate over-prediction of PTC >6. CONCLUSIONS: Our findings indicate that using plasma concentrations of rocuronium bromide estimated with either of the two models, combined with a PD model, provides equal model performance when predicting PTC. These promising results may provide an important advance in guiding rocuronium bromide administration when profound NMB in routine clinical practice is desired.

Foreseeing postoperative pain in neurosurgical patients: pupillometry predicts postoperative pain ratings-an observational study.

Pupillary reflex dilation (PRD) is triggered by noxious stimuli and diminished by opioid administration. In the postoperative period, PRD has been shown to be correlated with pain reporting and a useful tool to guide opioid administration. In this study we assessed whether pupillary measurements taken before extubation were related with the patient's reported pain in the Post-Anesthesia Care Unit (PACU) using the Numerical Rating Scale (NRS). Our objective was to evaluate the correlation of PRD and pupillary variables measured intraoperatively with postoperative pain under the same opioid concentration. This was a prospective observational study of 26 neurosurgical patients undergoing general anesthesia exclusively with propofol and remifentanil. A portable infrared pupillometer was used to provide an objective measure of pupil size and PRD (using the Pupillary Pain Index) before extubation. Pain ratings were obtained from patients after recovery of consciousness, while remifentanil was maintained at 2 ng/mL. A significant correlation was observed between NRS scores and pre-extubation PPI (rS = 0.62; P = 0.002), as well as between NRS scores and pupil diameter before tetanic stimulation PPI (rS = 0.56, P = 0.006). We also found a negative correlation between pupil diameter and age (rS = - 0.42, P = 0.04). The statistically significant correlation between pre-extubation PPI scores and NRS scores, as well as between the pupillary diameter before tetanic stimulation and NRS scores suggest the possibility of titrating analgesia at the end of the intraoperative period based on individual responses. This could allow clinicians to identify the ideal remifentanil concentration for the postoperative period.

Systematic Review on Rocuronium Continuous Infusion for Deep Neuromuscular Blockade.

BACKGROUND: Rocuronium is a muscle relaxant with increased use due to its binding relation with the reversal agent sugammadex. The purpose of this review entails the investigation of its use for the maintenance of Deep Neuromuscular Block (NMB) via continuous infusion. METHODS: Based on PRISMA systematic search guidelines, databases included PubMed, ISI Web of Science, Cochrane Library and Google Scholar. This comprehensive search addresses surgical patients under deep muscle relaxation via continuous rocuronium infusion. The main indicators were the rocuronium administration, NMB monitoring approaches and effects in order to maintain the deep level of relaxation, as well as reversal time after a standard dose of sugammadex. RESULTS: Despite the variance in approaches found in the literature, findings show the overall maintenance of deep NMB requires approximately 0.758 mg.kg-1h-1 of rocuronium (according to the PTC target of 0-10, 0-5 and 1-2, mean estimates are 0.445, 0.65 and 0.833 mg.kg-1h-1 respectively), suggesting that a lower range and a smaller maximum of PTC response require higher amount of rocuronium for its maintenance. The standard dose of sugammadex (4 mg/kg), administered at the end of the surgery takes longer [2.85 (1.17) min] than when they are administered after moderate NMB recovery [1.68 (0.47) min]. CONCLUSION: Continuous infusion for deep NMB presents inherent advantages in terms of maintenance and stability of muscle relaxation. Monitoring and rocuronium administration approaches are fundamental and intrinsically connected to provide a stable and improved maintenance of deep NMB.

Performance of blink reflex in patients during anesthesia induction with propofol and remifentanil: prediction probabilities and multinomial logistic analysis.

BACKGROUND: The amount of propofol needed to induce loss of responsiveness varied widely among patients, and they usually required less than the initial dose recommended by the drug package inserts. Identifying precisely the moment of loss of responsiveness will determine the amount of propofol each patient needs. Currently, methods to decide the exact moment of loss of responsiveness are based on subjective analysis, and the monitors that use objective methods fail in precision. Based on previous studies, we believe that the blink reflex can be useful to characterize, more objectively, the transition from responsiveness to unresponsiveness. The purpose of this study is to investigate the relation between the electrically evoked blink reflex and the level of sedation/anesthesia measured with an adapted version of the Richmond Agitation-Sedation Scale, during the induction phase of general anesthesia with propofol and remifentanil. Adding the blink reflex to other variables may allow a more objective assessment of the exact moment of loss of responsiveness and a more personalized approach to anesthesia induction. RESULTS: The electromyographic-derived features proved to be good predictors to estimate the different levels of sedation/anesthesia. The results of the multinomial analysis showed a reasonable performance of the model, explaining almost 70% of the adapted Richmond Agitation-Sedation Scale variance. The overall predictive accuracy for the model was 73.6%, suggesting that it is useful to predict loss of responsiveness. CONCLUSIONS: Our developed model was based on the information of the electromyographic-derived features from the blink reflex responses. It was able to predict the drug effect in patients undergoing general anesthesia, which can be helpful for the anesthesiologists to reduce the overwhelming variability observed between patients and avoid many cases of overdosing and associated risks. Despite this, future research is needed to account for variabilities in the clinical response of the patients and with the interactions between propofol and remifentanil. Nevertheless, a method that could allow for an automatic prediction/detection of loss of responsiveness is a step forward for personalized medicine.

Postdural puncture headache in the obstetric population: a new approach?

BACKGROUND AND OBJECTIVES: The gold standard for the treatment of postdural puncture headache (PDPH) is the epidural blood patch (EBP). Regional techniques-sphenopalatine ganglion block (SPGB), greater occipital nerve block (GONB) and trigger point infiltration (TPI)-can also be used for the treatment of PDPH. Our objective was to evaluate the efficacy of these peripheral nerve blocks (PNBs) in the treatment of PDPH. METHODS: A retrospective study was conducted including all patients with PDPH in the obstetrics department of our institution between April 2016 and December 2017. Data were retrieved from clinical records regarding anesthetic technique, symptoms, treatment, Numeric Pain Score (NPS) before and after treatment, among others. RESULTS: We observed 50 cases of PDPH: 25 following spinal anesthesia, 19 following epidural block and 6 following combined spinal-epidural. Of these, seven were managed conservatively and one received EBP as first-line treatment. The remaining 42 patients received PNB as first-line treatment. Of these, 27 received only 1 course of PNB, while 15 received 2 courses. We observed a statistically significant improvement in the NPS after the first course of blocks (n=42), with a reduction of the median NPS by 6.0 (IQR 4.0-7.5; p<0.001). Improvement was also observed after the second course of blocks (n=15), with a reduction of the median NPS of 3.5 (IQR 1.5-5.0; p=0.02). Due to treatment failure, 9 of the 42 patients treated with PNB required EBP. None of these were cases following spinal anesthesia. CONCLUSION: SPGB, GONB and TPI can be safe and effective options for treatment of PDPH, but do not completely eliminate the need for EBP. Prospective studies designed to identify factors associated with unsuccessful treatment are required.

Patterns of Hysteresis Between Induction and Emergence of Neuroanesthesia Are Present in Spinal and Intracranial Surgeries.

BACKGROUND: Recovery of consciousness is usually seen as a passive process, with emergence from anesthesia depicted as the inverse process of induction resulting from the elimination of anesthetic drugs from their central nervous system sites of action. However, that need not be the case. Recently it has been argued that we might encounter hysteresis to changes in the state of consciousness, known as neural inertia. This phenomenon has been debated in neuroanesthesia, as manipulation of the brain might further influence recovery of consciousness. The present study is aimed at assessing hysteresis between induction and emergence under propofol-opioid neuroanesthesia in humans using estimated propofol concentrations in both spinal and intracranial surgeries. METHODS: We identified the moments of loss (LOR) and recovery of responsiveness (ROR) in 21 craniotomies and 25 spinal surgeries. Propofol was given slowly until loss of responsiveness and stopped at the end of surgery. An opioid was present at induction and recovery. Propofol infused was recorded and plasma and effect-site concentrations were estimated using 2 pharmacokinetic models. Dose-response curves were generated. Estimated propofol plasma and effect-site concentrations were compared to assess hysteresis. RESULTS: Estimated propofol concentrations at LOR and ROR showed hysteresis. Whether for spinal or intracranial surgeries, the EC50 of propofol at which half of the patients entered and exited the state of responsiveness was significantly different. CONCLUSIONS: Hysteresis was observed between propofol concentrations at LOR and ROR, in both patients presenting for spinal and intracranial surgeries. Manipulation of the brain does not appear to change patterns of hysteresis, suggesting that neural inertia may occur in humans, in a way similar to that found in animal species. These findings justify performing a clinical study in patients using measured propofol concentrations to assess neural inertia.

CR-POSSUM and Surgical Apgar Score as predictive factors for patients' allocation after colorectal surgery / Escore CR-POSSUM e Índice de Apgar Cirúrgico como fatores preditivos para a alocação de pacientes após cirurgia colorretal

Abstract Background and objectives Surgical patients frequently require admission in high-dependency units or intensive care units. Resources are scarce and there are no universally accepted admission criteria, so patients' allocation must be optimized. The purpose of this study was to investigate the relationship between postoperative destination of patients submitted to colorectal surgery and the scores ColoRectal Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (CR-POSSUM) and Surgical Apgar Score (SAS) and, secondarily find cut-offs to aid this allocation. Methods A cross-sectional prospective observational study, including all adult patients undergoing colorectal surgery during a 2 years period. Data collected from the electronic clinical process and anesthesia records. Results A total of 358 patients were included. Median score for SAS was 8 and CR-POSSUM had a median mortality probability of 4.5%. Immediate admission on high-dependency units/intensive care units occurred in 51 patients and late admission in 18. Scores from ward and high-dependency units/intensive care units patients were statistically different (SAS: 8 vs. 7, p < 0.001; CR-POSSUM: 4.4% vs. 15.9%, p < 0.001). Both scores were found to be predictors of immediate postoperative destination (p < 0.001). Concerning immediate high-dependency units/intensive care units admission, CR-POSSUM showed a strong association (AUC 0.78, p = 0.034) with a ≥9.16 cut-off point (sensitivity: 62.5%; specificity: 75.2%), outperforming SAS (AUC 0.67, p = 0.048), with a ≤7 cut-off point (sensitivity: 67.3%; specificity: 56.1%). Conclusions Both CR-POSSUM and SAS were associated with the clinical decision to admit a patient to the high-dependency units/intensive care units immediately after surgery. CR-POSSUM alone showed a better discriminative capacity.

Resumo Justificativa e objetivos Os pacientes cirúrgicos com frequência precisam de internação em unidade de alta dependência ou unidade de terapia intensiva. Os recursos são escassos e não há critérios de admissão universalmente aceitos; portanto, a alocação dos pacientes precisa ser aprimorada. O objetivo primário deste estudo foi investigar a relação entre o destino dos pacientes após cirurgia colorretal e o Índice de Apgar Cirúrgico (IAC) e o escore CR-POSSUM - do inglês ColoRectal Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity - e, secundariamente, descobrir pontos de corte para auxiliar essa alocação. Métodos Estudo prospectivo de observação transversal, incluiu todos os pacientes adultos submetidos à cirurgia colorretal durante um período de dois anos. Os dados foram coletados do prontuário clínico eletrônico e dos registros de anestesia. Resultados Foram incluídos 358 pacientes. A mediana para o IAC foi 8 e para a probabilidade de mortalidade no CR-POSSUM, 4,5%. A admissão imediata em unidade de alta dependência/unidade de terapia intensiva ocorreu em 51 pacientes e a admissão tardia em 18. Os escores dos pacientes na enfermaria e na unidade de alta dependência/unidade de terapia intensiva foram estatisticamente diferentes (tempo de internação: 8 vs. 7, p < 0,001; CR-POSSUM: 4,4% vs. 15,9%, p < 0,001). Os dois escores foram preditivos do destino imediato pós-cirurgia (p < 0,001). Em relação à admissão imediata em UAD/UTI, CR-POSSUM mostrou uma forte associação (ASC 0,78; p = 0,034) com um ponto de corte ≥ 9,16 (sensibilidade: 62,5%; especificidade: 75,2%), superou o IAC (ASC 0,67, p = 0,048), com ponto de corte ≤ 7 (sensibilidade: 67,3%; especificidade: 56,1%). Conclusões Tanto o CR-POSSUM quanto o IAC foram associados à decisão clínica de admitir um paciente em unidade de alta dependência/unidade de terapia intensiva imediatamente após a cirurgia. CR-POSSUM isolado mostrou uma capacidade discriminativa melhor.

[CR-POSSUM and Surgical Apgar Score as predictive factors for patients' allocation after colorectal surgery]. / Escore CR­POSSUM e Índice de Apgar Cirúrgico como fatores preditivos para a alocação de pacientes após cirurgia colorretal.

BACKGROUND AND OBJECTIVES: Surgical patients frequently require admission in high-dependency units or intensive care units. Resources are scarce and there are no universally accepted admission criteria, so patients' allocation must be optimized. The purpose of this study was to investigate the relationship between postoperative destination of patients submitted to colorectal surgery and the scores ColoRectal Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (CR-POSSUM) and Surgical Apgar Score (SAS) and, secondarily find cut-offs to aid this allocation. METHODS: A cross-sectional prospective observational study, including all adult patients undergoing colorectal surgery during a 2 years period. Data collected from the electronic clinical process and anesthesia records. RESULTS: A total of 358 patients were included. Median score for SAS was 8 and CR-POSSUM had a median mortality probability of 4.5%. Immediate admission on high-dependency units/intensive care units occurred in 51 patients and late admission in 18. Scores from ward and high-dependency units/intensive care units patients were statistically different (SAS: 8 vs. 7, p<0.001; CR-POSSUM: 4.4% vs. 15.9%, p<0.001). Both scores were found to be predictors of immediate postoperative destination (p<0.001). Concerning immediate high-dependency units/intensive care units admission, CR-POSSUM showed a strong association (AUC 0.78, p=0.034) with a ≥9.16 cut-off point (sensitivity: 62.5%; specificity: 75.2%), outperforming SAS (AUC 0.67, p=0.048), with a ≤7 cut-off point (sensitivity: 67.3%; specificity: 56.1%). CONCLUSIONS: Both CR-POSSUM and SAS were associated with the clinical decision to admit a patient to the high-dependency units/intensive care units immediately after surgery. CR-POSSUM alone showed a better discriminative capacity.

Post-operative pain after ultrasound transversus abdominis plane block versus trocar site infiltration in laparoscopic nephrectomy: a prospective study / Dor no período pós-operatório de nefrectomia laparoscópica com bloqueio do plano transverso abdominal guiado por ultrassom versus infiltração do sítio do trocarte: um estudo prospectivo

Abstract Background Transversus abdominis plane (TAP) block is useful in reducing post-operative pain in laparoscopic nephrectomy compared to placebo. The purpose of this work is to compare post-operative pain and recovery after TAP block or trocar site infiltration (TSI) in this surgery. Methods A prospective, single blinded study on patients scheduled for laparoscopic nephrectomy. Patients were assigned to two groups: TSI Group: trocar site infiltration at the end of surgery; TAP Group: unilateral ultrasound-guided TAP block after induction. Sevoflurane and remifentanil, in a target controlled infusion mode, were used for maintenance of general anesthesia. Before the end of surgery paracetamol, tramadol and morphine were administered. Visual analogue scale (VAS 0-100 mm) at rest and with cough was applied in three moments: in recovery room (T1 at admission and T2 before discharge) and 24 h after surgery (T3). Pain scores with incentive spirometer were also evaluated at T3. In recovery, morphine was administered as a rescue drug whenever VAS > 30 mm. Time to oral intake, chair sitting, ambulation and length of hospital stay were evaluated 24 h after surgery. Statistical analysis: Student's t-test and Chi-square test, and linear regression models. A p-value < 0.05 was considered significant. Data are presented as mean (SD). Results Forty patients were enrolled in the study. The primary outcome variable, VAS pain scores did not show a statistical significant difference between groups (p > 0.05). VAS at rest (TAP vs. TSI groups) was: T1 = 33 ± 29 vs. 39 ± 32, T2 = 10 ± 9 vs. 17 ± 18 and T3 = 7 ± 12 vs. 10 ± 18. VAS with cough (TAP vs. TSI groups) was: T1 = 51 ± 34 vs. 45 ± 32, T2 = 24 ± 24 vs. 33 ± 23 and T3 = 20 ± 23 vs. 23 ± 23. VAS with incentive spirometer (TAP vs. TSI groups) was: T3 = 21 ± 27 vs. 21 ± 25. Intraoperative remifentanil consumption was similar between TAP (0.16 ± 0.07 mcg.kg-1.min-1) and TSI (0.18 ± 0.9 mcg.kg-1.min-1) groups. There were no differences in opioid consumption between TAP (4.4 ± 3.49 mg) and TSI (6.87 ± 4.83 mg) groups during recovery. Functional recovery parameters were not statistically different between groups. Conclusions Multimodal analgesia with TAP block did not show a significant clinical benefit compared with trocar site infiltration in laparoscopic nephrectomies.

Resumo Justificativa O bloqueio do plano transverso abdominal (TAP) é útil para reduzir a dor no pós-operatório de nefrectomia laparoscópica comparado com o placebo. O objetivo deste estudo foi comparar a dor no pós-operatório e a recuperação após bloqueio TAP ou infiltração do sítio do trocarte (TSI) nesse tipo de cirurgia. Métodos Estudo prospectivo e cego com pacientes agendados para nefrectomia laparoscópica. Os pacientes foram divididos em dois grupos: Grupo TSI: infiltração do sítio do trocarte ao final da cirurgia; Grupo TAP: bloqueio TAP unilateral guiado por ultrassom após a indução. Sevoflurano e remifentanil administrado em perfusão alvo-controlada foram usados para a manutenção da anestesia geral. Paracetamol, tramadol e morfina foram administrados antes do fim da cirurgia. Escala analógica visual (VAS 0-100 mm), para avaliar a dor em repouso e durante a tosse, foi aplicada em três momentos: na sala de recuperação [na admissão (T1) e antes da alta (T2)] e 24 horas após a cirurgia (T3). Os escores de dor com espirômetro de incentivo também foram avaliados em T3. Durante a recuperação, morfina foi administrada como medicamento de resgate, sempre que VAS > 30 mm. Os tempos até a ingestão oral, sentar em cadeira, deambulação e de permanência hospitalar foram avaliados 24 horas após a cirurgia. Análise estatística: teste t de Student, teste do qui-quadrado e modelos de regressão linear. Um valor de p < 0,05 foi considerado significativo. Os dados foram expressos em média (DP). Resultados Quarenta pacientes foram incluídos no estudo. Os escores do desfecho primário e da VAS não apresentaram diferença estatística significativa entre os grupos (p > 0,05). Os escores VAS em repouso (TAP vs. TSI) foram: T1 = 33 ± 29 vs. 39 ± 32; T2 = 10 ± 9 vs. 17 ± 18 e T3 = 7 ± 12 vs. 10 ± 18. Os escores VAS durante a tosse (TAP vs. TSI) foram: T1 = 51 ± 34 vs. 45 ± 32; T2 = 24 ± 24 vs. 33 ± 23 e T3 = 20 ± 23 vs. 23 ± 23. Os escores VAS com espirômetro de incentivo (TAP vs. TSI) foram: T3 = 21 ± 27 vs. 21 ± 25. O consumo de remifentanil no intraoperatório foi semelhante entre os grupos TAP (0,16 ± 0,07 mcg.kg-1.min-1) e TSI (0,18 ± 0,9 mcg.kg-1.min-1). Não houve diferença no consumo de opioides entre os grupos TAP (4,4 ± 3,49 mg) e TSI (6,87 ± 4,83 mg) durante a recuperação. Os parâmetros funcionais de recuperação não foram estatisticamente diferentes entre os grupos. Conclusões A analgesia multimodal com bloqueio TAP não mostrou benefício clínico significativo comparado com a infiltração do sítio do trocarte em nefrectomia laparoscópica.

[Post-operative pain after ultrasound transversus abdominis plane block versus trocar site infiltration in laparoscopic nephrectomy: a prospective study]. / Dor no período pós­operatório de nefrectomia laparoscópica com bloqueio do plano transverso abdominal guiado por ultrassom versus infiltração do sítio do trocarte: um estudo prospectivo.

BACKGROUND: Transversus abdominis plane (TAP) block is useful in reducing post-operative pain in laparoscopic nephrectomy compared to placebo. The purpose of this work is to compare post-operative pain and recovery after TAP block or trocar site infiltration (TSI) in this surgery. METHODS: A prospective, single blinded study on patients scheduled for laparoscopic nephrectomy. Patients were assigned to two groups: TSI Group: trocar site infiltration at the end of surgery; TAP Group: unilateral ultrasound-guided TAP block after induction. Sevoflurane and remifentanil, in a target controlled infusion mode, were used for maintenance of general anesthesia. Before the end of surgery paracetamol, tramadol and morphine were administered. Visual analogue scale (VAS 0-100mm) at rest and with cough was applied in three moments: in recovery room (T1 at admission and T2 before discharge) and 24h after surgery (T3). Pain scores with incentive spirometer were also evaluated at T3. In recovery, morphine was administered as a rescue drug whenever VAS>30mm. Time to oral intake, chair sitting, ambulation and length of hospital stay were evaluated 24h after surgery. STATISTICAL ANALYSIS: Student's t-test and Chi-square test, and linear regression models. A p-value<0.05 was considered significant. Data are presented as mean (SD). RESULTS: Forty patients were enrolled in the study. The primary outcome variable, VAS pain scores did not show a statistical significant difference between groups (p>0.05). VAS at rest (TAP vs. TSI groups) was: T1=33±29 vs. 39±32, T2=10±9 vs. 17±18 and T3=7±12 vs. 10±18. VAS with cough (TAP vs. TSI groups) was: T1=51±34 vs. 45±32, T2=24±24 vs. 33±23 and T3=20±23 vs. 23±23. VAS with incentive spirometer (TAP vs. TSI groups) was: T3=21±27 vs. 21±25. Intraoperative remifentanil consumption was similar between TAP (0.16±0.07mcg.kg-1.min-1) and TSI (0.18±0.9mcg.kg-1.min-1) groups. There were no differences in opioid consumption between TAP (4.4±3.49mg) and TSI (6.87±4.83mg) groups during recovery. Functional recovery parameters were not statistically different between groups. CONCLUSIONS: Multimodal analgesia with TAP block did not show a significant clinical benefit compared with trocar site infiltration in laparoscopic nephrectomies.

A novel multivariate STeady-state index during general ANesthesia (STAN).

The assessment of the adequacy of general anesthesia for surgery, namely the nociception/anti-nociception balance, has received wide attention from the scientific community. Monitoring systems based on the frontal EEG/EMG, or autonomic state reactions (e.g. heart rate and blood pressure) have been developed aiming to objectively assess this balance. In this study a new multivariate indicator of patients' steady-state during anesthesia (STAN) is proposed, based on wavelet analysis of signals linked to noxious activation. A clinical protocol was designed to analyze precise noxious stimuli (laryngoscopy/intubation, tetanic, and incision), under three different analgesic doses; patients were randomized to receive either remifentanil 2.0, 3.0 or 4.0 ng/ml. ECG, PPG, BP, BIS, EMG and [Formula: see text] were continuously recorded. ECG, PPG and BP were processed to extract beat-to-beat information, and [Formula: see text] curve used to estimate the respiration rate. A combined steady-state index based on wavelet analysis of these variables, was applied and compared between the three study groups and stimuli (Wilcoxon signed ranks, Kruskal-Wallis and Mann-Whitney tests). Following institutional approval and signing the informed consent thirty four patients were enrolled in this study (3 excluded due to signal loss during data collection). The BIS index of the EEG, frontal EMG, heart rate, BP, and PPG wave amplitude changed in response to different noxious stimuli. Laryngoscopy/intubation was the stimulus with the more pronounced response [Formula: see text]. These variables were used in the construction of the combined index STAN; STAN responded adequately to noxious stimuli, with a more pronounced response to laryngoscopy/intubation (18.5-43.1 %, [Formula: see text]), and the attenuation provided by the analgesic, detecting steady-state periods in the different physiological signals analyzed (approximately 50 % of the total study time). A new multivariate approach for the assessment of the patient steady-state during general anesthesia was developed. The proposed wavelet based multivariate index responds adequately to different noxious stimuli, and attenuation provided by the analgesic in a dose-dependent manner for each stimulus analyzed in this study.

Effect of Boussignac continuous positive airway pressure ventilation on Pao2 and Pao2/Fio2 ratio immediately after extubation in morbidly obese patients undergoing bariatric surgery: a randomized controlled trial.

STUDY OBJECTIVE: Pathophysiological changes after laparoscopic Roux-en-Y gastric bypass may increase the risk of pulmonary complications in morbidly obese patients. The purpose of the study was to assess the impact of immediate postextubation use of Boussignac continuous positive airway pressure (CPAP) on arterial oxygenation in morbidly obese patients undergoing laparoscopic Roux-en-Y gastric bypass. The hypothesis is that the use of CPAP may improve oxygenation in the postoperative period when compared to Venturi mask. DESIGN: Randomized controlled study. SETTING: A tertiary referral hospital. PATIENTS: Recruited morbidly obese adult patients undergoing laparoscopic Roux-en-Y gastric bypass. INTERVENTIONS: Boussignac CPAP or Venturi mask was randomly applied immediately after extubation in the operating room and was maintained during the first 2 hours in the recovery room. MEASUREMENTS: Pao2 and Pao2/fraction of inspired oxygen (Fio2) ratio values were measured preoperatively and at 1 (T1), 2 (T2), and 24 hours (T24) after extubation, through arterial blood samples. Secondary outcomes (spirometric parameters) were measured at the same periods. For comparison between groups, Student t test, Mann-Whitney U nonparametric test, and χ(2) test were used. Statistical significance is at P < .05. MAIN RESULTS: Twenty-four patients were included, 12 in each group. There were no differences in preoperative evaluation. There were significant differences between groups in Pao2 and Pao2/Fio2 mean values at T1, T2, and T24, being superior in the Boussignac group. During the 24 hours postextubation, 9% of patients in the Boussignac group and 50% in the Venturi group had a Pao2 less than 60 mm Hg in at least 1 of the evaluations. After extubation, a Pao2/Fio2 ratio value less than 300 was observed in all patients in the Venturi group and in 55% in Boussignac group in at least 1 of the evaluations. There were no differences in spirometric parameters between groups at T1, T2, and T24. CONCLUSIONS: Application of Boussignac CPAP for 2 hours after extubation improved oxygenation but did not improve forced expiratory volume at 1 second and forced vital capacity.

The Effects of Different Concentrations of the α2-Adrenoceptor Agonist Medetomidine on Basal Excitatory Synaptic Transmission and Synaptic Plasticity in Hippocampal Slices of Adult Mice.

BACKGROUND: α2-Adrenoceptor agonists are used frequently in human and veterinary anesthesia as sedative/analgesic drugs. However, they can impair cognition. Little is known about the concentration-dependent effects of α2-adrenoceptor agonists on synaptic plasticity, the neurophysiological basis of learning and memory. Therefore, we investigated the effects of different concentrations of medetomidine, an α2-adrenoceptor agonist, on basal excitatory synaptic transmission and on 2 forms of synaptic plasticity: paired-pulse facilitation (PPF) and long-term potentiation (LTP). METHODS: Evoked field excitatory postsynaptic potentials were recorded in Schaffer fibers-CA1 pyramidal cell synapses of mouse hippocampal slices, and the initial field excitatory postsynaptic potentials slope was measured. For basal synaptic transmission and PPF, increasing concentrations of medetomidine (1-200 µM) were applied to each slice. For LTP experiments, individual slices were used for each tested concentration of medetomidine (0.1-0.4 µM), where LTP induction and LTP maintenance were measured. RESULTS: The lower tested concentrations of medetomidine decreased LTP in a concentration-dependent manner, whereas greater concentrations were required to decrease fiber volley amplitude and basal excitatory synaptic transmission. PPF was only affected by the greatest concentration (200 µM). CONCLUSIONS: Medetomidine decreased LTP in the mouse hippocampus, in accordance with the ability of medetomidine to induce memory deficits.

Effect of propofol and remifentanil on a somatosensory evoked potential indicator of pain perception intensity in volunteers.

Somatosensory evoked potentials (SEPs) have been linked to noxious activation and stimulus intensity. In this exploratory study we investigated the impact of anaesthetic drugs on SEPs and pain ratings, to assess their applicability as an objective measure of the nociception/anti-nociception balance. Following institutional approval and written informed consent, 10 healthy adult volunteers were enrolled (29.5 ± 9.1 years, 63.0 ± 8.9 kg and 171.4 ± 7.2). Median nerve electrical stimulation was adjusted according to volunteers' sensitive, motor and painful thresholds (PT). Baseline SEPs were registered, and remifentanil and propofol administered using a stair scheme TCI. For each drug combination a 1.3×PT stimulus was administered, and volunteers evaluated pain intensity in a numerical rating scale (0-10). SEPs' amplitudes and latencies were normalized by the baseline values, reducing volunteers' intervariability. Stimulation currents varied between 6-52 mA (1.3×PT) and pain ratings between 0 and 9. Cortical SEPs latencies were decreased for higher stimulus intensities (P < 0.01), accompanied by increased pain ratings (P < 0.01). An individually adjusted/normalized ratio based on cortical SEPs amplitude and interpeak latency is proposed([Formula: see text]): [Formula: see text] and NSR were significantly correlated in three out of nine subjects, and [Formula: see text] and remifentanil Ce were significantly correlated in two (low number of evaluation points). [Formula: see text] was shown to decrease with increasing doses of propofol and remifentanil (P < 0.05). The proposed metric was depressed by anaesthetics and reflected pain evaluations. Further research is necessary to increase the number of volunteers and drugs' combination, to assess its applicability during surgically adequate anesthetic leves.

Increased lung inflammation with oxygen supplementation in tracheotomized spontaneously breathing rabbits: an experimental prospective randomized study.

BACKGROUND: Mechanical ventilation is a well-known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation. METHODS: A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy. RESULTS: All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis. CONCLUSIONS: Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.

EMG contributes to improve Cerebral State Index modeling in dogs anesthesia.

Cerebral State Index (CSI) is a measure of depth of anesthesia (DoA) developed for humans, which is traditionally modeled with the Hill equation and the propofol effect-site concentration (Ce). The CSI has been studied in dogs and showed several limitations related to the interpretation of EEG data. Nevertheless, the CSI has a lot of potential for DoA monitoring in dogs, it just needs to be adjusted for this species. In this work, an adapted CSI model is presented for dogs considering a) both Ce and EMG as inputs and b) a fuzzy logic structure with parameters optimized using the ANFIS method. The new model is compared with traditional Hill model using data from dogs in routine surgery. The results showed no significant impact in the model performance with the change of model structure (Fuzzy instead of Hill). The residuals of the Hill model were significantly correlated with the EMG, indicating that the latter should be considered in the model. In fact, the EMG introduction in CSI model significantly decreased the modeling error: 11.8 [8.6; 15.2] (fuzzy logic) versus 20.9 [16.4; 29.0] (Hill). This work shows that CSI modeling in dogs can be improved using the current human anesthesia set-up, once the EMG signal is acquired simultaneously with the CSI index. However, it does not invalidate the search of new DoA indices more adjusted to use in dog's anesthesia.

Anaesthesia synchronization software: target controlled infusion system evaluation.

Target Controlled Infusion (TCI) systems are based in drug Pharmacokinetic (Pk) and Pharmacodynamic (Pd) models implemented in an algorithm to drive an infusion device. Several studies had compare manual titration of anesthesia and TCI system use; some studies evaluate the performance of the control algorithms for TCI systems, and a considerable number of studies assess the performance of Pk/Pd models implemented into TCI systems. This study presents a set of tests to validate the performance of a TCI system as a computer-aided. The goal of the current study was to assess the performance of the TCI system, Anaesthesia Synchronization Software (ASYS), on clinical set up to evaluate communication consistence (computer - infusion device) and controller performance in real time. These measures provided quantitative and qualitative evidences of software robustness and accuracy to be used at clinical environment.

A wavelet based method for steady-state detection in anesthesia.

With the recent concern on patient's outcome following general anesthesia, automatic control of drugs has been a field of interest. The Bispectral Index (BIS) is an EEG based hypnosis monitor, in current use at the operating theatre as a guiding tool for the anesthesiologist to titrate drugs, and prevent awareness. When trying to model a certain process, it's very important to obtain information of the system behavior under steady-state conditions. In this study the hypnotic and analgesic drugs' effect on the hypnosis index BIS was analyzed, in order to obtain steady-state information of the system response (inputs-output), and in the future model the drugs combined effect. A steady-state index was obtained using a wavelet analysis technique for trend detection. This tool may be used in the future to model the drug's combined effect on the hypnosis indices, and also to bring some insight on disturbances not related to drug changes.