Effects Of Anesthetic Drugs Research Articles

The influence of propofol anesthesia exposure on nonaversive memory retrieval and expression of molecules involved in memory process in the dorsal hippocampus in peripubertal rats.

The effects of anesthetic drugs on postoperative cognitive function in children are not well defined and have not been experimentally addressed. The present study aimed to examine the influence of propofol anesthesia exposure on nonaversive hippocampus-dependent learning and biochemical changes involved in memory process in the dorsal hippocampus, in peripubertal rats as the rodent model of periadolescence. The intersession spatial habituation and the novel object recognition tasks were used to assess spatial and nonspatial, nonaversive hippocampus-dependent learning. The exposure to anesthesia was performed after comparably long acquisition phases in both tasks. Behavioral testing lasted for 2 consecutive days (24-hour retention period). Changes in the expression of molecules involved in memory retrieval/reconsolidation were examined in the dorsal hippocampus by Western blot and immunohistochemistry, at the time of behavioral testing. Exposure to propofol anesthesia resulted in inappropriate assessment of spatial novelty at the beginning of the test session and affected continuation of acquisition in the spatial habituation test. The treatment did not affect recognition of the novel object at the beginning of the test session but it attenuated overall preference to novelty, reflecting retrieval of a weak memory. The expression of phosphorylated extracellular signal-regulated kinase 2 (involved in memory retrieval) was decreased while the level of phosphorylated Ca2+ /calmodulin-dependent protein kinase IIα and early growth response protein 1 (involved in memory reconsolidation) was increased in the dorsal hippocampus. The level of Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog B (neuronal activity indicator) was increased in the dorsal dentate gyrus. Enhanced exploratory activity was still evident in the propofol anesthesia exposure (PAE) group 48hour after the treatment in both tasks. In peripubertal rats, propofol anesthesia exposure affects memory retrieval and acquisition of new learning in the spatial and nonspatial, nonaversive learning tasks 24hour after the treatment, along with the expression of molecules that participate in memory retrieval/reconsolidation in the dorsal hippocampus. These results may have clinical implications, favoring control of basic cognitive functions in older children after the propofol exposure.

Delineating the Trajectory of Cognitive Recovery From General Anesthesia in Older Adults: Design and Rationale of the TORIE (Trajectory of Recovery in the Elderly) Project.

Mechanistic aspects of cognitive recovery after anesthesia and surgery are not yet well characterized, but may be vital to distinguishing the contributions of anesthesia and surgery in cognitive complications common in the elderly such as delirium and postoperative cognitive dysfunction. This article describes the aims and methodological approach to the ongoing study, Trajectory of Recovery in the Elderly (TORIE), which focuses on the trajectory of cognitive recovery from general anesthesia. The study design employs cognitive testing coupled with neuroimaging techniques such as functional magnetic resonance imaging, diffusion tensor imaging, and arterial spin labeling to characterize cognitive recovery from anesthesia and its biological correlates. Applying these techniques to a cohort of age-specified healthy volunteers 40-80 years of age, who are exposed to general anesthesia alone, in the absence of surgery, will assess cognitive and functional neural network recovery after anesthesia. Imaging data are acquired before, during, and immediately after anesthesia, as well as 1 and 7 days after. Detailed cognitive data are captured at the same time points as well as 30 days after anesthesia, and brief cognitive assessments are repeated at 6 and 12 months after anesthesia. The study is underway. Our primary hypothesis is that older adults may require significantly longer to achieve cognitive recovery, measured by Postoperative Quality of Recovery Scale cognitive domain, than younger adults in the immediate postanesthesia period, but all will fully recover to baseline levels within 30 days of anesthesia exposure. Imaging data will address systems neuroscience correlates of cognitive recovery from general anesthesia. The data acquired in this project will have both clinical and theoretical relevance regardless of the outcome by delineating the mechanism behind short-term recovery across the adult age lifespan, which will have major implications for our understanding of the effects of anesthetic drugs.

Anesthesia-Associated Relative Hypovolemia: Mechanisms, Monitoring, and Treatment Considerations.

Although the utility and benefits of anesthesia and analgesia are irrefutable, their practice is not void of risks. Almost all drugs that produce anesthesia endanger cardiovascular stability by producing dose-dependent impairment of cardiac function, vascular reactivity, and compensatory autoregulatory responses. Whereas anesthesia-related depression of cardiac performance and arterial vasodilation are well recognized adverse effects contributing to anesthetic risk, far less emphasis has been placed on effects impacting venous physiology and venous return. The venous circulation, containing about 65–70% of the total blood volume, is a pivotal contributor to stroke volume and cardiac output. Vasodilation, particularly venodilation, is the primary cause of relative hypovolemia produced by anesthetic drugs and is often associated with increased venous compliance, decreased venous return, and reduced response to vasoactive substances. Depending on factors such as patient status and monitoring, a state of relative hypovolemia may remain clinically undetected, with impending consequences owing to impaired oxygen delivery and tissue perfusion. Concurrent processes related to comorbidities, hypothermia, inflammation, trauma, sepsis, or other causes of hemodynamic or metabolic compromise, may further exacerbate the condition. Despite scientific and technological advances, clinical monitoring and treatment of relative hypovolemia still pose relevant challenges to the anesthesiologist. This short perspective seeks to define relative hypovolemia, describe the venous system’s role in supporting normal cardiovascular function, characterize effects of anesthetic drugs on venous physiology, and address current considerations and challenges for monitoring and treatment of relative hypovolemia, with focus on insights for future therapies.

The effects of anesthetic drug choice on heart rate variability in dogs.

Objective:The objective of this study was to assess the effects of anesthetic drugs on heart rate (HR) and heart rate variability (HRV) in dogs.Materials and Methods:Twelve healthy client-owned dogs of various breeds, including five females and seven males were used for elective surgery in this study. The dogs were pre-medicated with four protocols; (1) alfaxalone [at 3 mg/kg body weight (bwt)], (2) zolazepam + tiletamine (Zoletil) (at 5 mg/kg bwt), (3) diazepam (at 0.3 mg/kg bwt) + ketamine (at 5 mg/kg bwt), and (4) diazepam (at 0.3 mg/kg bwt) + propofol (at 5 mg/kg bwt). The HR and HRV of 12 dogs were recorded 20 min before and after the administration of the anesthetic drugs. Doppler was used to obtain systolic, diastolic, and mean blood pressures.Results:After anesthetic drug administration, the dogs pre-medicated and inducted with alfaxalone had the lowest HR values as compared with those of other protocols. The HRV low frequency and high frequency power ratio decreased in the dogs pre-medicated and intubated with alfaxalone.Conclusion:This study demonstrates that alfaxalone preserves the cardiovascular function; and hence, is considered as safe to use for the surgical applicability in dogs.

Magnitude of Airway Problems at a University Teaching and Referral Hospital Recovery Room of Low Resource Setting-A Cross Sectional Study

Background: Airway management is a basic life-saving intervention which is used when the patient’s breathing effort is compromised due to various reasons. Postsurgical patients are at risk of developing airway problems due to co-morbidities, intraoperative complications, surgery and anaesthetic drug effects. The severity of illness, analgesic drugs like narcotics and postoperative standard of monitoring may impact on breathing process of the patients. We aimed to assess the magnitude of airway problems at the recovery room. Methods and material: Cross sectional study conducted at a referral hospital recovery room, 2014. Standardized checklist used for data collection. All patients with airway problem who admitted at the recovery room during the study period were included in the study. Descriptive statistics and Chi-square were used. Results: One hundred seventy seven patients developed airway problems over five months duration. Of these, 47.5%, 32.2%, and 20.3% patients developed mild, moderate and severe airway problems respectively. The major airway problems were desaturation (62.7%), respiratory arrest (14.7%), aspiration (18.1%), bronchospasm (3.4%) and laryngospasm (1.1%) respectively. Factors associated with severity of airway problems were ASA status (P=0.031), type of trauma (P=0.026), intraoperative analgesia (P=0.020) and type of patient (P=0.049). The interventions made were ETTI or LMA (35%) patients, nasopharyngeal airway insertion (21.5%), oral airway (14.1%), oxygen supplementation (10.2%), surgical airway (9.6%), recovery position (7.3%) and emergency airway manoeuvre (2.3%) respectively. Anaesthetists involved in airway management in 30.5% of patients. Conclusion: The magnitude of airway problem was high. We recommend the availability of well trained staff for airway management and fulfilment of basic equipments and drugs for patient monitoring and resuscitation. High airway problems are an alarm for the need for well-equipped recovery room with well trained staff, patient monitoring and resuscitation materials.

Synthetic Patient Database of Drug Effect in General Anesthesia for Evaluation of Estimation and Control Algorithms

This paper describes a database of synthetic patients for the use in estimation and control design in closed-loop anesthesia. The synthetic patients are represented by pharmacokinetic-pharmacodynamic (PKPD) Wiener models for the Depth of Anesthesia estimated from clinical data. The input of the Wiener model is given by the flow rates of propofol and remifentanil while the output is the bispectral index. A positive stable realization of the Wiener model describing the system dynamics is adopted to ensure a biologically feasible behavior of the PKPD system. Both time-varying and time-invariant versions of the models are available. An Extended Kalman filter (EKF) is applied to the clinical data to estimate the patient-dependent parameters of the Wiener model. The time-invariant version of a model is obtained by averaging of the time-varying estimates produced by the EKF. The performance of the Wiener model with estimated parameters is assessed and discussed. To illustrate the utility of the database, a PID controller is evaluated over the synthetic patient cohort.

Perioperative events influence cancer recurrence risk after surgery.

Surgery is a mainstay treatment for patients with solid tumours. However, despite surgical resection with a curative intent and numerous advances in the effectiveness of (neo)adjuvant therapies, metastatic disease remains common and carries a high risk of mortality. The biological perturbations that accompany the surgical stress response and the pharmacological effects of anaesthetic drugs, paradoxically, might also promote disease recurrence or the progression of metastatic disease. When cancer cells persist after surgery, either locally or at undiagnosed distant sites, neuroendocrine, immune, and metabolic pathways activated in response to surgery and/or anaesthesia might promote their survival and proliferation. A consequence of this effect is that minimal residual disease might then escape equilibrium and progress to metastatic disease. Herein, we discuss the most promising proposals for the refinement of perioperative care that might address these challenges. We outline the rationale and early evidence for the adaptation of anaesthetic techniques and the strategic use of anti-adrenergic, anti-inflammatory, and/or antithrombotic therapies. Many of these strategies are currently under evaluation in large-cohort trials and hold promise as affordable, readily available interventions that will improve the postoperative recurrence-free survival of patients with cancer.

Postoperative delirium and postoperative cognitive dysfunction: updates in pathophysiology, potential translational approaches to clinical practice and further research perspectives.

Postoperative delirium, the onset of confusion/delirium during the early postoperative phase, is the most common postoperative complication in older adults and represents a medical emergency that requires immediate assessment and treatment. On the other hand, the term postoperative cognitive decline or dysfunction refers to a wide spectrum of clinical conditions featuring a decline in a variety of neuropsychological domains including memory, executive functioning, and speed of processing emerging week to months after anesthesia and surgery. Postoperative delirium and postoperative cognitive decline represent two distinct clinical entities along the continuum of cognitive impairment after anesthesia and surgery. All patients experiencing delirium does however not develop postoperative dysfunction and likewise all patients showing various degree of postoperative decline have not explicitly exhibited postoperative delirium. Although neuroinflammation seems to be main cause, the exact pathophysiology of both phenomena is very difficult to ascertain because it involves the crossroads of many mechanisms. This paper aimed to provide an update in the pathophysiology of these conditions with special attention to the roles of the neuroinflammation, the microglia activation, the surgical stress response, the impairment of neurotransmitter systems, and the direct neurotoxic effect of general anesthetic drugs. Potential translational approaches to clinical practice and further research perspectives are also given.

Sugammadex Rescue in Avoiding Intensive Care Unit Admission in an Octogenarian Undergoing Emergency Laparotomy

Postlaparotomy management for elderly patients with underlying comorbidities is always a challenge because of poor cardiorespiratory reserves and prolonged effect of anesthetic drugs. For these reasons, such patients usually require intensive care unit (ICU) admission in the postoperative period. We report a case of an 85-year-old chronic smoker with controlled diabetes mellitus who needed an emergency laparotomy for a perforated gastric ulcer. Unfortunately, there was a shortage of ICU backup. With the successful conduct of an early surgery using combined general and regional anesthesia, the use of sugammadex (Bridion, Merck Sharp & Dohme Corp, Oss, the Netherlands) as a reversal agent, a skilled surgeon, and good postanesthesia care, the patient did not require ICU admission. He recovered fast and was discharged home 4days after surgery. This case study aims to contribute to the literature on experience of a successful conduct of anesthesia in a high-risk geriatric patient when ICU facilities are limited.

Bottom-Up and Top-Down Mechanisms of General Anesthetics Modulate Different Dimensions of Consciousness.

There has been controversy regarding the precise mechanisms of anesthetic-induced unconsciousness, with two salient approaches that have emerged within systems neuroscience. One prominent approach is the “bottom up” paradigm, which argues that anesthetics suppress consciousness by modulating sleep-wake nuclei and neural circuits in the brainstem and diencephalon that have evolved to control arousal states. Another approach is the “top-down” paradigm, which argues that anesthetics suppress consciousness by modulating the cortical and thalamocortical circuits involved in the integration of neural information. In this article, we synthesize these approaches by mapping bottom-up and top-down mechanisms of general anesthetics to two distinct but inter-related dimensions of consciousness: level and content. We show how this explains certain empirical observations regarding the diversity of anesthetic drug effects. We conclude with a more nuanced discussion of how levels and contents of consciousness interact to generate subjective experience and what this implies for the mechanisms of anesthetic-induced unconsciousness.

Influence of general anaesthesia on the brainstem

The exact role of the brainstem in the control of body functions is not yet well known and the same applies to the influence of general anaesthesia on brainstem functions. Nevertheless in all general anaesthesia the anaesthesiologist should be aware of the interaction of anaesthetic drugs and brainstem function in relation to whole body homeostasis. As a result of this interaction there will be changes in consciousness, protective reflexes, breathing pattern, heart rate, temperature or arterial blood pressure to name a few. Brainstem function can be explored using three different approaches: clinically, analyzing changes in brain electric activity or using neuroimaging techniques. With the aim of providing the clinician anaesthesiologist with a global view of the interaction between the anaesthetic state and homeostatic changes related to brainstem function, the present review article addresses the influence of anaesthetic drug effects on brainstem function through clinical exploration of cranial nerves and reflexes, analysis of electric signals such as electroencephalographic changes and what it is known about brainstem through the use of imaging techniques, more specifically functional magnetic resonance imaging.

Effect of age on the performance of bispectral and entropy indices during sevoflurane pediatric anesthesia: a pharmacometric study.

Bispectral index (BIS) and entropy monitors have been proposed for use in children, but research has not supported their validity for infants. However, effective monitoring of young children may be even more important than for adults, to aid appropriate anesthetic dosing and reduce the chance of adverse consequences. This prospective study aimed to investigate the relationships between age and the predictive performance of BIS and entropy monitors in measuring the anesthetic drug effects within a pediatric surgery setting. We concurrently recorded BIS and entropy (SE/RE) in 48 children aged 1 month-12 years, undergoing general anesthesia with sevoflurane and fentanyl. Nonlinear mixed effects modeling was used to characterize the concentration-response relationship independently between the three monitor indicators with sevoflurane. The model's goodness-of-fit was assessed by prediction-corrected visual predictive checks. Model fit with age was evaluated using absolute conditional individual weighted residuals (|CIWRES|). The ability of BIS and entropy monitors to describe the effect of anesthesia was compared with prediction probabilities (PK ) in different age groups. Intraoperative and awakening values were compared in the age groups. The correlation between BIS and entropy was also calculated. |CIWRES| vs age showed an increasing trend in the model's accuracy for all three indicators. PK probabilities were similar for all three indicators within each age group, though lower in infants. The linear correlations between BIS and entropy in different age groups were lower for infants. Infants also tended to have lower values during surgery and at awakening than older children, while toddlers had higher values. Performance of both monitors improves as age increases. Our results suggest a need for the development of new monitor algorithms or calibration to better account for the age-specific EEG dynamics of younger patients.

Can we reduce anesthesia exposure? Neonatal brain MRI: Swaddling vs. sedation, a national survey

Study objectiveNeonatal magnetic resonance imaging (MRI) is a diagnostic modality that requires minimal motion to acquire quality images. Sedation or even general anesthesia may be necessary to achieve acceptable scans. There is a growing body of literature, especially in animal studies, that links neurotoxicity with anesthetic exposure to the developing brain. There is no study outlining strategies used by neonatal intensive care units (NICU) to achieve quality MRI images with limited exposure to medications identified as possibly harmful to the developing brain. DesignA 15-question survey was sent to all NICU programs in the United States (US) with fellowship programs. SettingMRI suite. PatientsNeonates. InterventionsNone. MeasurementsThe programs were queried regarding their preferred method for obtaining MRIs of the brain and how successful they were in obtaining quality images. Main resultsOf the 96 programs surveyed, 58 responded (response rate of 60%). To obtain brain MRIs, 64%(n=37) used feed and swaddle; 32% (n=19) use sedation; and 3% (n=2) used general anesthesia (GA). Success rate of obtaining quality MRI images varied by technique. In the feed and swaddle group, 81% reported that a failure to obtain useful images occurred <25%; 11% reported that it occurred 25–75%; and 5% reported that it occurred >75%. In the sedation and GA group, 100% reported failure to obtain useful images occurred rarely. ConclusionsThe majority of NICUs in the US that responded to the survey utilized feed and swaddle as their primary technique for obtaining MRIs of the brain and reported a high success rate. Given the growing concern over the possible neurotoxic effects of anesthetic drugs on the developing brain, more centers should consider this technique as a first line method to obtain brain MRIs, with sedation and GA reserved for failed feed and swaddle attempts and special circumstances.

The Effect of Propofol on Plasma Membrane Ultrastructure in the Intact Cells

Despite many observed effects of anesthetic drugs, the mechanism of general anesthesia is still unknown.One well-studied drug used for human anesthesia, propofol, has been shown to interact with some ligand gated ion-channels. However, propofol also easily dissolves in the lipid bilayer and alters membrane fluidity. Which mechanism dominates in anesthesia or even how anesthesia arises are unclear. Here, we study the influence of propofol on plasma membrane (PM) ultrastructure in intact cells, which affect cell signaling. In the PM, transient submicroscopic nano-domains form by interactions between lipid-acyl-chains or lipid head groups, stabilized by cholesterol. In addition, membrane cytoskeleton may further regulate these nano-domains. These domains regulate receptor interactions and signaling.We study transient propofol affects on these domains from low to clinically relevant propofol concentrations by analyzing diffusion of GFP-tagged outer leaflet/inner leaflet membrane proteins.Using bimFCS we measure diffusion on multiple length scales simultaneously. We observe that at lower propofol concentrations (up to 2υM), the cholesterol nano-domains trap the GPI-mGFP less, which is consistent with the recent studies showing that propofoldecreases the phase transition temperature of plasma membrane derived vesicles. Interestingly, at higher concentrations of propofol (20υM to 150υM), the nanodomains trap the GPI-mGFP more strongly. This is only observed at physiological temperatures (37°C). By inhibiting myosin activity or actin filaments (de-)polymerization, we find that the activity of actin filaments further alters the behavior of cholesterol nano-domains due to propofol. We compare the effect of propofol and its analog confirming its specific effect as anesthetic drug. These results suggest that in intact cells, propofol induced cholesterol nano-domains changes are temperature dependent, regulated by cytoskeleton activities, and the effect is specific comparing to its analogs.

An innovative technique to improve safety of volatile anesthetics suction from the cardiopulmonary bypass circuit.

Context:Myocardial injury during cardiac surgery on cardiopulmonary bypass (CPB) is a major determinant of morbidity and mortality. Preclinical and clinical evidence of dose- and time-related cardioprotective effects of volatile anesthetic drugs exist and their use during the whole surgery duration could improve perioperative cardiac protection. Even if administering volatile agents during CPB are relatively easy, technical problems, such as waste gas scavenging, may prevent safe and manageable administration of halogenated vapors during CPB.Aims:The aim of this study is to improve the safe administration of volatile anesthesia during CPB.Settings and Design:Tertiary teaching hospital.Subjects and Methods:We describe an original device that collects and disposes of any volatile anesthetic vapors present in the exit stream of the oxygenator, hence preventing its dispersal into the operating theatre environment and adaptively regulates pressure of oxygenator chamber in the CPB circuit.Results:We have so far applied a prototype of this device in more than 1300 adult cardiac surgery patients who received volatile anesthetics during the CPB phase.Conclusions:Widespread implementation of scavenging system like the one we designed may facilitate the perfusionist and the anesthesiologist in delivering these cardioprotective drugs with beneficial impact on patients’ outcome without compromising on safety.

Improved spectrum analysis in EEG for measure of depth of anesthesia based on phase-rectified signal averaging

The definition of the depth of anesthesia (DOA) is still controversial and its measurement is not completely standardized in modern anesthesia. Power spectral analysis is an important method for feature detection in electroencephalogram (EEG) signals. Several spectral parameters derived from EEG have been proposed for measuring DOA in clinical applications. In the present paper, an improved method based on phase-rectified signal averaging (PRSA) is designed to improve the predictive accuracy of relative alpha and beta power, a frequency band power ratio, total power, median frequency (MF), spectral edge frequency 95 (SEF95), and spectral entropy for assessing anesthetic drug effects. Fifty-six patients undergoing general anesthesia in an operating theatre are studied. All EEG signals are continuously recorded from the awake state to the end of the recovery state and then filtered using multivariate empirical mode decomposition (MEMD). All parameters are evaluated using the commercial bispectral index (BIS) and expert assessment of conscious level (EACL), respectively. The ability to predict DOA is estimated using the area under the receiver-operator characteristics curve (AUC). All indicators based on the improved method can clearly discriminate the conscious state from the anesthetized state after filtration (p < 0.05). A significantly larger mean AUC (p < 0.05) shows that the improved method performs better than the conventional method to measure the DOA in most circumstances. Especially for raw EEG contaminated by artifacts, when the BIS index is used to indicate the consciousness level, the improvement is 7.37% (p < 0.05), 9.04% (p < 0.05), 18.46% (p < 0.05), 27.73% (p < 0.05), 14.65% (p < 0.05), 2.52%, 5.38% and 6.24% (p < 0.05) for relative alpha and beta power, power ratio, total power, MF, SEF, RE and SE, respectively. However, when the EACL is used to indicate the consciousness level, the improvement is 3.30% (p < 0.05), 16.69% (p < 0.05), 15.08% (p < 0.05), 34.83% (p < 0.05), 27.78% (p < 0.05), 5.89% (p < 0.05), 26.05% (p < 0.05) and 23.42% (p < 0.05). Spectral parameters derived from PRSA are more useful to measure the DOA in noisy cases.

Intravenous nutrients for preventing inadvertent perioperative hypothermia in adults.

Inadvertent perioperative hypothermia (a drop in core temperature to below 36°C) occurs because normal temperature regulation is disrupted during surgery, mainly because of the effects of anaesthetic drugs and exposure of the skin for prolonged periods. Many different ways of maintaining body temperature have been proposed, one of which involves administration of intravenous nutrients during the perioperative period that may reduce heat loss by increasing metabolism, thereby increasing heat production. To assess the effectiveness of preoperative or intraoperative intravenous nutrients in preventing perioperative hypothermia and its complications during surgery in adults. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; November 2015) in the Cochrane Library; MEDLINE, Ovid SP (1956 to November 2015); Embase, Ovid SP (1982 to November 2015); the Institute for Scientific Information (ISI) Web of Science (1950 to November 2015); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL, EBSCO host; 1980 to November 2015), as well as the reference lists of identified articles. We also searched the Current Controlled Trials website and ClincalTrials.gov. Randomized controlled trials (RCTs) of intravenous nutrients compared with control or other interventions given to maintain normothermia in adults undergoing surgery. Two review authors extracted data and assessed risk of bias for each included trial, and a third review author checked details if necessary. We contacted some study authors to request additional information. We included 14 trials (n = 565), 13 (n = 525) of which compared intravenous administration of amino acids to a control (usually saline solution or Ringer's lactate). The remaining trial (n = 40) compared intravenous administration of fructose versus a control. We noted much variation in these trials, which used different types of surgery, variable durations of surgery, and different types of participants. Most trials were at high or unclear risk of bias owing to inappropriate or unclear randomization methods, and to unclear participant and assessor blinding. This may have influenced results, but it is unclear how results might have been influenced.No trials reported any of our prespecified primary outcomes, which were risk of hypothermia and major cardiovascular events. Therefore, we decided to analyse data related to core body temperature instead as a primary outcome. It was not possible to conduct meta-analysis of data related to amino acid infusion for the 60-minute and 120-minute time points, as we observed significant statistical heterogeneity in the results. Some trials showed that higher temperatures were associated with amino acids, but not all trials reported statistically significant results, and some trials reported the opposite result, where the amino acid group had a lower core temperature than the control group. It was possible to conduct meta-analysis for six studies (n = 249) that provided data relating to the end of surgery. Amino acids led to a statistically significant increase in core temperature in comparison to those receiving control (MD = 0.46°C 95% CI 0.33 to 0.59; I2 0.0%; random-effects; moderate quality evidence).Three trials (n = 155) reported shivering as an outcome. Meta-analysis did not show a clear effect, and so it is uncertain whether amino acids reduce the risk of shivering (RR 0.36, 95% CI 0.13 to 1.00; I2 = 93%; random-effects model; very low-quality evidence). Intravenous amino acids may keep participants up to a half-degree C warmer than the control. This difference was statistically significant at the end of surgery, but not at other time points. However, the clinical importance of this finding remains unclear. It is also unclear whether amino acids have any effect on the risk of shivering and if intravenous nutrients confer any other benefits or harms, as high-quality data about these outcomes are lacking.

Influencia de la anestesia general sobre el tronco encefálico

The exact role of the brainstem in the control of body functions is not yet well known and the same applies to the influence of general anaesthesia on brainstem functions. Nevertheless in all general anaesthesia the anaesthesiologist should be aware of the interaction of anaesthetic drugs and brainstem function in relation to whole body homeostasis. As a result of this interaction there will be changes in consciousness, protective reflexes, breathing pattern, heart rate, temperature or arterial blood pressure to name a few. Brainstem function can be explored using three different approaches: clinically, analyzing changes in brain electric activity or using neuroimaging techniques. With the aim of providing the clinician anaesthesiologist with a global view of the interaction between the anaesthetic state and homeostatic changes related to brainstem function, the present review article addresses the influence of anaesthetic drug effects on brainstem function through clinical exploration of cranial nerves and reflexes, analysis of electric signals such as electroencephalographic changes and what it is known about brainstem through the use of imaging techniques, more specifically functional magnetic resonance imaging.

A desflurane and fentanyl dosing regimen for wake-up testing during scoliosis surgery: Implications for the time-course of emergence from anesthesia.

The Stagnara wake-up test assesses neurological deficits during scoliosis surgery, and response surface interaction models for opioids and inhaled agents predicts anesthetic drug effects. We hypothesized that there is an optimal desflurane-fentanyl dosing regimen that can provide a faster and more predictable wake-up time, while also ensuring adequate analgesia during wake-up testing. Twenty-three American Society of Anesthesiologists Class I-II scoliosis patients who received desflurane-fentanyl anesthetic regimens were enrolled in this posthoc study, and their intraoperative drug administration data were collected retrospectively. Desflurane and fentanyl effect site concentrations were calculated using pharmacokinetic models, and converted to equivalent remifentanil-sevoflurane concentrations. Results were fitted into Greco models for predicting the probability of an Observers Assessment of Alertness/Sedation score of <2. At time of wake-up, the models correctly predicted the probability that patients would respond to voice prompts and prodding was approximately 50%. The probability of pain intensity was distributed between 50% and 95%, indicating a low degree of pain at emergence. When comparing subgroups defined by calculated effect-site fentanyl concentrations, the wake-up time in the intermediate concentration group was significantly shorter than that in the high concentration group (p=0.024). This study provides evidence that desflurane-fentanyl-based anesthesia is conducive to rapid emergence followed by an immediate neurological evaluation. Intermediate fentanyl effect-site concentrations (1-2ng/mL) at time of wake-up were associated with good balance between rapid emergence and adequate analgesia. Furthermore, we believe that generalizing response surface models to a variety of inhalation agent-opioid combinations using simple relative potency relationships is possible and practical.

Anaesthesia and deep brain stimulation

AbstractDeep brain stimulation (DBS) is becoming an increasingly popular minimally invasive surgical procedure for various movement disorders, especially Parkinson’s disease. Different nuclei have been identified depending on patients’ symptoms, but the success or failure of the procedure depends on various other factors such as proper patient selection and risk-benefit analysis. While various techniques of anaesthesia including monitored anaesthesia care, conscious sedation and general anaesthesia are being used routinely, no clear-cut evidence exists as to the best technique for this procedure. This review article discusses the surgical procedure of DBS, devices currently available, perioperative anaesthetic concerns and techniques, effect of anaesthetic drugs on microelectrode recordings and macro-stimulation and associated complications.