Mapping general anesthesia states based on electro-encephalogram transition phases.

Cortical electro-encephalography (EEG) served as the clinical reference for monitoring unconsciousness during general anesthesia. The existing EEG-based monitors classified general anesthesia states as underdosed, adequate, or overdosed, lacking predictive power due to the absence of transition phases among these states. In response to this limitation, we undertook an analysis of the EEG signal during isoflurane-induced general anesthesia in mice. Adopting a data-driven approach, we applied signal processing techniques to track θ- and δ-band dynamics, along with iso-electric suppressions. Combining this approach with machine learning, we successfully developed an automated algorithm. The findings of our study revealed that the dampening of the δ-band occurred several minutes before the onset of significant iso-electric suppression episodes. Furthermore, a distinct γ-frequency oscillation was observed, persisting for several minutes during the recovery phase subsequent to isoflurane-induced overdose. As a result of our research, we generated a map summarizing multiple brain states and their transitions, offering a tool for predicting and preventing overdose during general anesthesia. The transition phases identified, along with the developed algorithm, have the potential to be generalized, enabling clinicians to prevent inadequate anesthesia and, consequently, tailor anesthetic regimens to individual patients.

Clinical Practice: Should we Radically Alter our Sedation of Critical Care Patients, Especially Given the COVID-19 Pandemics?

The high number of patients infected with the SARS-CoV-2 virus requiring care for ARDS puts sedation in the critical care unit (CCU) to the edge. Depth of sedation has evolved over the last 40 years (no-sedation, deep sedation, daily emergence, minimal sedation, etc.). Most guidelines now recommend determining the depth of sedation and minimizing the use of benzodiazepines and opioids. The broader use of alpha-2 adrenergic agonists ('alpha-2 agonists') led to sedation regimens beginning at admission to the CCU that contrast with hypnotics+opioids ("conventional" sedation), with major consequences for cognition, ventilation and circulatory performance. The same doses of alpha-2 agonists used for 'cooperative' sedation (ataraxia, analgognosia) elicit no respiratory depression but modify the autonomic nervous system (cardiac parasympathetic activation, attenuation of excessive cardiac and vasomotor sympathetic activity). Alpha-2 agonists should be selected only in patients who benefit from their effects ('personalized' indications, as opposed to a 'one size fits all' approach). Then, titration to effect is required, especially in the setting of systemic hypotension and/or hypovolemia. Since no general guidelines exist for the use of alpha-2 agonists for CCU sedation, our clinical experience is summarized for the benefit of physicians in clinical situations in which a recommendation might never exist (refractory delirium tremens; unstable, hypovolemic, hypotensive patients, etc.). Because the physiology of alpha-2 receptors and the pharmacology of alpha-2 agonists lead to personalized indications, some details are offered. Since interactions between conventional sedatives and alpha-2 agonists have received little attention, these interactions are addressed. Within the existing guidelines for CCU sedation, this article could facilitate the use of alpha-2 agonists as effective and safe sedation while awaiting large, multicentre trials and more evidence-based medicine.

Inflammation increases MMP levels via PGE2 in human vascular wall and plasma of obese women.

BACKGROUND AND OBJECTIVES: Matrix metalloproteinases (MMPs) are involved in several inflammatory processes including obesity-related vascular diseases and graft failure of coronary artery (CA) bypass grafts [internal mammary artery (IMA), saphenous vein (SV)]. In these inflammatory conditions, the release of prostaglandin E2 (PGE2) is increased via the activity of inducible microsomal PGE synthase-1 (mPGES-1). Our aim was to investigate whether MMPs and their endogenous inhibitor (TIMPs) may be regulated by PGE2 under inflammatory conditions in human vasculature and perivascular adipose tissue (PVAT), as well as in plasma of obese patients. METHODS: MMP-1,-2 and TIMP-1,-2 densities were measured in human plasma (n = 68) as well as in supernatants of human vascular wall (IMA n = 16, SV n = 14, CA n = 13) and their PVAT. The effects of inflammation and mPGES-1 inhibitor (Compound III, 10 µM) on MMPs regulation were evaluated. The correlations between PGE2 and several parameters were calculated in plasma from patients with or without obesity. RESULTS: The vascular wall and PVAT from SV exhibited the greatest MMP-1,-2 release. An increase of MMP-1,-2 and/or a decrease of TIMP-1 quantities have been detected under inflammation only in vascular wall not in PVAT. These changes under inflammation were completely reversed by inhibition of mPGES-1. In obesity, C-reactive protein (CRP), biomarker of inflammation, and PGE2 levels were increased. PGE2 contents were positively correlated with some anthropometric parameters and plasmatic CRP in both genders, while the correlation with the plasmatic MMP-1 density was significant only in women. CONCLUSIONS: The greater MMP activity observed in SV may contribute to the increased prevalence of graft failure. Under inflammation, the greater mPGES-1 and PGE2 levels lead to enhanced MMP activity in human vascular walls. The positive association between PGE2 and MMP-1 or CRP has been observed in plasma of women. We suggest that mPGES-1 inhibitors could prevent graft failure and obesity-related vascular remodeling mostly in women.

Low end-tidal CO2 as a real-time severity marker of intra-anaesthetic acute hypersensitivity reactions.

BACKGROUND: Prompt diagnosis of intra-anaesthetic acute hypersensitivity reactions (AHR) is challenging because of the possible absence and/or difficulty in detecting the usual clinical signs and because of the higher prevalence of alternative diagnoses. Delayed epinephrine administration during AHR, because of incorrect/delayed diagnosis, can be associated with poor prognosis. Low end-tidal CO2 (etCO2) is known to be linked to low cardiac output. Yet, its clinical utility during suspected intra-anaesthetic AHR is not well documented. METHODS: Clinical data from the 86 patients of the Neutrophil Activation in Systemic Anaphylaxis (NASA) multicentre study were analysed. Consenting patients with clinical signs consistent with intra-anaesthetic AHR to a neuromuscular blocking agent were included. Severe AHR was defined as a Grade 3-4 of the Ring and Messmer classification. Causes of AHR were explored following recommended guidelines. RESULTS: Among the 86 patients, 50% had severe AHR and 69% had a confirmed/suspected IgE-mediated event. Occurrence and minimum values of arterial hypotension, hypocapnia and hypoxaemia increased significantly with the severity of AHR. Low etCO2 was the only factor able to distinguish mild [median 3.5 (3.2;3.9) kPa] from severe AHR [median 2.4 (1.6;3.0) kPa], without overlap in inter-quartile range values, with an area under the receiver operator characteristic curve of 0.92 [95% confidence interval: 0.79-1.00]. Among the 41% of patients who received epinephrine, only half received it as first-line therapy despite international guidelines. CONCLUSIONS: An etCO2 value below 2.6 kPa (20 mm Hg) could be useful for prompt diagnosis of severe intra-anaesthetic AHR, and could facilitate early treatment with titrated doses of epinephrine. CLINICAL TRIAL REGISTRATION: NCT01637220.

Anaphylactic bronchospasm during general anesthesia is not related to asthma.

In the general population, a history of asthma (HA) is associated with a higher risk of mortality of anaphylactic shock (AS), but it is unknown whether this association remains valid for intra-operative AS. The goal of this retrospective study was to investigate whether a HA was associated with a higher risk of bronchospasm during intra-operative AS. We analyzed 106 patients (January 2009-December 2012) with intra-operative AS: 57% of them had a confirmed IgE-mediated reaction and 27% had a HA. On logistic regression, the only factor statistically associated with bronchospasm was a neuromuscular blocking drug, with both IgE- or non-IgE-mediated reactions. These results suggest that the mechanisms of bronchospasm in AS may be different from those of asthma and that, in the presence of bronchospasm during anesthesia, AS should be considered to be the most likely cause.

[Veno-venous extracorporeal oxygenation and veno-arterial extracorporeal oxygenation. Questions, answers]. / Assistance respiratoire veino-veineuse et assistance circulatoire veino-artérielle avec oxygénation extracorporelle. Questions, réponses.

A round table, organized by the French Society of Perfusion (Sofraperf) at the French national congress on extracorporeal circulations (Perfusion 2013), was attended by perfusionists, anaesthesiologists, intensivists and surgeons around the theme of respiratory veno-venous support and veno-arterial circulatory support with extracorporeal oxygenation in intensive care units. The debate was conducted in a participatory manner by bi-directional questions-answers session between moderators and assistance. The authors report management of this type of therapy that is not perfectly homogeneous, supported on literature data. Cannulae, cannulation, circuit, oxygenator, anticoagulation, control, surveillance, weaning are subject to paragraphs with defined entry whose contents are mutually enriching.

Time to achieve target mean arterial pressure during resuscitation from experimental anaphylactic shock in an animal model. A comparison of adrenaline alone or in combination with different volume expanders.

Anaphylactic shock is a rare, but potentially lethal complication, combining life-threatening circulatory failure and massive fluid shifts. Treatment guidelines rely on adrenaline and volume expansion by intravenous fluids, but there is no solid evidence for the choice of one specific type of fluid over another. Our purpose was to compare the time to achieve target mean arterial pressure upon resuscitation using adrenaline alone versus adrenaline with different resuscitation fluids in an animal model and to compare the tissue oxygen pressures (PtiO2) with the various strategies. Twenty-five ovalbumin-sensitised Brown Norway rats were allocated to five groups after anaphylactic shock induction: vehicle (CON), adrenaline alone (AD), or adrenaline with isotonic saline (AD+IS), hydroxyethyl starch (AD+HES) or hypertonic saline (AD+HS). Time to reach a target mean arterial pressure value of 75 mmHg, cardiac output, skeletal muscle PtiO2, lactate/pyruvate ratio and cumulative doses of adrenaline were recorded. Non-treated rats died within 15 minutes. The target mean arterial pressure value was reached faster with AD+HES (median: 10 minutes, range: 7.5 to 12.5 minutes) and AD+IS (median: 17.5 minutes, range: 5 to 25 minutes) versus adrenaline alone (median: 25 minutes, range: 20-30 minutes). There were also reduced adrenaline requirements in these groups. The skeletal muscle PtiO2 was restored only in the AD+HES group. Although direct extrapolation to humans should be made with caution, our results support the combined use of adrenaline and volume expansion for resuscitation from anaphylactic shock. When used with adrenaline the most effective fluid was hydroxyethyl starch, whereas hypertonic saline was the least effective.

[Temporary epicardial pacing following cardiac surgery: practical aspects]. / Entraînement électrosystolique épicardique temporaire post-chirurgie cardiaque: modalités pratiques.

OBJECTIVES: To review the practical aspects of temporary epicardial pacing following open heart surgery. METHODS: Review of articles published in English or French within the last five years and investigating temporary epicardial pacing (indications, pacing modes, epicardial wires and temporary generators). The studies were extracted from the databases ScienceDirect and Pubmed. RESULTS: Temporary epicardial pacing is used to treat severe conduction and/or rhythm disorders, but also to improve hemodynamics by optimizing selected temporary pacing settings. Temporary epicardial pacing consists in choosing the most suitable pacing mode according to the situation (surgery, patient, conduction and/or rhythm abnormalities) and setting its parameters that ensure : i) optimal pacemaker functioning; ii) epicardial electrodes longevity; iii) the most favorable hemodynamic profiles. Management of temporary pacing settings and their regular adjustment, at least daily and based on thresholds, are part of good clinical practices. Nevertheless, the French literature lacks official recommendations for temporary epicardial pacing. CONCLUSION: Temporary epicardial pacing following cardiac surgery is a simple method, more effective than transcutaneous pacing and easier to implement than transvenous pacing. Its practical management should be known by all physicians (anesthetists, cardiac surgeons) as well as paramedical personnel in order to avoid the risks of suboptimal functioning. A good practice protocol is proposed at the end of the manuscript.

[Anaesthetic management of patients with bicuspid aortic valve for delivery. About two consecutive cases]. / Prise en charge anesthésique de l'accouchement des patientes porteuses d'une bicuspidie aortique. À propos de deux cas consécutifs.

Cardiac diseases are the second cause of non-obstetrical death during pregnancy in France. Bicuspid aortic valve is the most frequent congenital cardiac disease but its characteristics are little known. We report two consecutive cases of pregnant patients with aortic bicuspidy, one with a severe aortic stenosis and one with a severe dilatation of the ascending aorta. We describe the anaesthetic management of delivery for these two cases and summarize the current recommendations for management of this condition during pregnancy.

The role of prostaglandin E2 in human vascular inflammation.

Prostaglandins (PG) are the product of a cascade of enzymes such as cyclooxygenases and PG synthases. Among PG, PGE2 is produced by 3 isoforms of PGE synthase (PGES) and through activation of its cognate receptors (EP1-4), this PG is involved in the pathophysiology of vascular diseases. Some anti-inflammatory drugs (e.g. glucocorticoids, nonsteroidal anti-inflammatory drugs) interfere with its metabolism or effects. Vascular cells can initiate many of the responses associated with inflammation. In human vascular tissue, PGE2 is involved in many physiological processes, such as increasing vascular permeability, cell proliferation, cell migration and control of vascular smooth muscle tone. PGE2 has been shown to contribute to the pathogenesis of atherosclerosis, abdominal aortic aneurysm but also in physiologic/adaptive processes such as angiogenesis. Understanding the roles of PGE2 and its cognate receptors in vascular diseases could help to identify diagnostic and prognostic biomarkers. In addition, from these recent studies new promising therapeutic approaches like mPGES-1 inhibition and/or EP4-antagonism should be investigated.

[Dexmedetomidine and clonidine: a review of their pharmacodynamy to define their role for sedation in intensive care patients]. / Dexmédétomidine et clonidine : revue de leurs propriétés pharmacodynamiques en vue de définir la place des agonistes alpha-2 adrénergiques dans la sédation en réanimation.

Alpha-2 adrenergic agonists ("alpha-2 agonists") present multiple pharmacodynamic effects: rousable sedation, decreased incidence of delirium in the setting of critical care, preservation of respiratory drive, decreased whole body oxygen consumption, decreased systemic and pulmonary arterial impedance, improved left ventricular systolic and diastolic function, preserved vascular reactivity to exogenous catecholamines, preserved vasomotor baroreflex with lowered set point, preserved kidney function, decreased protein catabolism. These pharmacodynamic effects explain the interest for these drugs in the critical care setting. However, their exact role for sedation in critically ill-patients remains open for further studies. Given the few double-blind randomized multicentric trials available, the present non exhaustive analysis of the literature aims at presenting the utilization of alpha-2 agonists as potential first-line sedative agents, in the critical care setting. Suggestions regarding the use of alpha-2 agonists as sedatives are detailed.

[Regulation of vasomotor tone]. / Régulation du tonus vasomoteur.

This article provides a synthesis of physiology and pathophysiology of the cardiovascular system and briefly presents the principles of regulation at the level of the whole organism and regional circulations. Decision algorithms, based on knowledge of physiology and pathophysiology are proposed. Their goal is to contribute to the improvement of cardiopulmonary bypass practice.

PGE(2) receptor (EP(4)) agonists: potent dilators of human bronchi and future asthma therapy?

BACKGROUND: Asthma and chronic obstructive pulmonary disease are characterized by inappropriate constriction of the airway smooth muscle. In this context, the physiological response of the human airways to selective relaxant agonists like PGE(2) is highly relevant. The aim of this study was thus to characterize the PGE(2) receptor subtypes (EP(2) or EP(4)) involved in the relaxation of human bronchial preparations. METHODS: Human bronchial preparations cut as rings were mounted in organ baths for isometric recording of tension and a pharmacological study was performed using selective EP(2) or EP(4) ligands. RESULTS: In the presence of a thromboxane TP receptor antagonist and indomethacin, PGE(2) induced the relaxation of human bronchi (E(max) = 86 ± 04% of papaverine response; pEC(50) value = 7.06 ± 0.13; n = 6). This bronchodilation was significantly blocked by a selective EP(4) receptor antagonist (GW627368X, 1 and 10 µmol/L) with a pK(B) value of 6.38 ± 0.19 (n = 5). In addition, the selective EP(4) receptor agonists (ONO-AE1-329; L-902688), but not the selective EP(2) receptor agonist (ONO-AE1-259), induced potent relaxation of bronchial preparations pre-contracted with histamine or anti-IgE. CONCLUSION: PGE(2) and EP(4) agonists induced potent relaxations of human bronchial preparations via EP(4) receptor. These observations suggest that EP(4) receptor agonists could constitute therapeutic agents to treat the increased airway resistance in asthma.

[Fast recovery of haemodynamic and ventilatory functions after sugammadex bolus following rocuronium-induced anaphylactic shock refractory to conventional treatment]. / Récupération hémodynamique et ventilatoire rapide après injection de sugammadex lors d'un choc anaphylactique au rocuronium, réfractaire au traitement conventionnel.

Recently, three case reports have suggested the possible efficacy of sugammadex in anaphylactic shock refractory to conventional treatment induced by rocuronium. We report a new case of severe anaphylactic reaction to rocuronium treated with sugammadex. After 18 minutes of conventional treatment because of persistent cardiocirculatory failure and bronchospasm, a bolus of 2000 mg (18 mg/kg) of sugammadex was injected. This was associated with rapid correction of arterial hypotension and bronchoconstriction. The underlying pathophysiological mechanisms that explain the potential beneficial effect of sugammadex in this context are unknown but it is important to know that refractory anaphylactic shock to rocuronium can be potentially corrected with sugammadex.

Assessment of salivary amylase as a stress biomarker in pregnant patients.

BACKGROUND: Chronic stress during pregnancy has been associated with worsened maternal and fetal outcomes. Acute stress immediately before spinal anaesthesia for caesarean section may contribute to hypotension. Therefore objective measures of acute stress may help identify women at risk of adverse outcomes. Salivary alpha-amylase is a stress biomarker that has so far been poorly investigated during pregnancy. The reference change value is the difference between two sequential results that must be exceeded for a change to be considered clinically relevant. Our first aim was to determine if salivary alpha-amylase increased in pregnant patients when subjected to the stress of transfer to the operating room. Our second aim was to determine if changes in salivary alpha-amylase were likely to be clinically significant by measuring reference change value in healthy volunteers. METHODS: In 15 pregnant patients undergoing planned caesarean section under spinal anaesthesia, salivary alpha-amylase, systolic blood pressure, heart rate, and immediate anxiety were measured on the morning of surgery on the ward and again in the operating room. The reference change value was calculated from 18 healthy volunteers. RESULTS: A median 220% increase in salivary alpha-amylase activity (P=0.0015) and a 17% increase in systolic blood pressure (P=0.0006) were observed between the ward and operating room. No changes of immediate anxiety or heart rate were observed. Reference change value was ±76% in volunteers and 13 of the 15 pregnant patients had a salivary alpha-amylase increase greater than the reference change value. CONCLUSION: When pregnant women are taken to the operating room, a clinically and statistically significant increase in salivary alpha-amylase was observed. Further studies are required to define its clinical usefulness.

Impact of preoperative maintenance or interruption of aspirin on thrombotic and bleeding events after elective non-cardiac surgery: the multicentre, randomized, blinded, placebo-controlled, STRATAGEM trial.

BACKGROUND: Patients receiving anti-platelet agents for secondary cardiovascular prevention frequently require non-cardiac surgery. A substantial proportion of these patients have their anti-platelet drug discontinued before operation; however, there is uncertainty about the impact of this practice. The aim of this study was to compare the effect of maintenance or interruption of aspirin before surgery, in terms of major thrombotic and bleeding events. METHODS: Patients treated with anti-platelet agents for secondary prevention and undergoing intermediate- or high-risk non-cardiac surgery were included in this multicentre, randomized, placebo-controlled, trial. We substituted non-aspirin anti-platelets with aspirin (75 mg daily) or placebo starting 10 days before surgery. The primary outcome was a composite score evaluating both major thrombotic and bleeding adverse events occurring within the first 30 postoperative days weighted by their severity (weights were established a priori using a Delphi consensus process). Analyses followed the intention-to-treat principle. RESULTS: We randomized 291 patients (n=145, aspirin group, and n=146, placebo group). The most frequent surgical procedures were orthopaedic surgery (52.2%), abdominal surgery (20.6%), and urologic surgery (15.5%). No significant difference was observed neither in the primary outcome score [mean values (SD)=0.67 (2.05) in the aspirin group vs 0.65 (2.04) in the placebo group, P=0.94] nor at day 30 in the number of major complications between groups. CONCLUSIONS: In these at-risk patients undergoing elective non-cardiac surgery, we did not find any difference in terms of occurrence of major thrombotic or bleeding events between preoperative maintenance or interruption of aspirin.