Obesity is becoming an epidemic health problem, and the number of surgical patients with a body mass index of more than 50 kg m−2 requiring anaesthesia is increasing. Obesity is associated with physiopathological changes such as metabolic syndrome, cardiovascular disorders, or sleep apnoea syndrome, most of which improve with weight loss. Regarding pharmacokinetics, volumes of distribution are increased for both lipophilic and hydrophilic drugs. Consequently, doses should be adjusted to total body weight (propofol for maintenance, succinylcholine, vancomycin), or lean body mass (remifentanil, non-depolarizing neuromuscular blocking agent). For all drugs, titration based on monitoring of effects is recommended. To minimize recovery delays, drugs with a rapid offset of action such as remifentanil and desflurane are preferable. Poor tolerance to apnoea with early hypoxaemia and atelectasis warrant rapid sequence induction and protective ventilation. Careful positioning will prevent pressure injuries and minimize rhabdomyolysis which are frequent. Because of an increased risk of pulmonary embolism, multimodal prevention is mandatory. Regional anaesthesia, albeit technically difficult, is beneficial in obese patients to treat postoperative pain and improve rehabilitation. Maximizing the safety of anaesthesia for morbidly obese patients requires a good knowledge of the physiopathology of obesity and great attention to detail in planning and executing anaesthetic management. Even in elective surgery, many cases can be technical challenges and only a step-by-step approach to the avoidance of potential adverse events will result in the optimal outcome.

Characterization of anaesthesia is tricky, in particular, to go beyond the usual definition of a 'state of non-responsiveness to various types of stimulations', and to find indicators useful for titrating drug administration. General anaesthesia is usually split into two main domains: unconsciousness (non-response to verbal stimulation and amnesia) and analgesia (non-response to noxious stimulations).1Prys-Roberts C Anaesthesia: a practical or impractical construct?.Br J Anaesth. 1987; 59: 1341-1345Abstract Full Text PDF PubMed Scopus (179) Google Scholar 2Shafer SL Stanski DR Defining depth of anesthesia.Handb Exp Pharmacol. 2008; : 409-423Crossref PubMed Scopus (35) Google Scholar Unconsciousness may be directly assessed at induction of anaesthesia (loss of verbal contact) and after recovery (absence of recall), but usually not during maintenance. The adequacy of the balance between analgesia and stimulation can be clinically estimated through movement, haemodynamic changes, and autonomic nervous system responses (sweat and lacrimation, modification in pupil diameter); these clinical endpoints have limitations when used for titrating anaesthetic drugs in clinical practice, specifically in paralysed patients. Furthermore, as adequate anaesthesia is defined as non-responsiveness, clinical assessment cannot distinguish between adequate drug delivery and overdosing if overdosing does not induce adverse effects. Monitoring systems have been developed to compensate for these limitations. These are based on indirect (surrogate) measures, including the observation and analysis of cortical EEG. Several parameters have thus been proposed, such as the bispectral index (BIS™)3Kearse Jr, LA Manberg P Chamoun N deBros F Zaslavsky A Bispectral analysis of the electroencephalogram correlates with patient movement to skin incision during propofol/nitrous oxide anesthesia.Anesthesiology. 1994; 81: 1365-1370Crossref PubMed Scopus (181) Google Scholar which still plays a predominant role, mainly due to the fact that it was the first commercially available device with a clearly defined range supposed to correspond to an adequate 'depth of anaesthesia'. As adrenergic stimuli induce arousal reactions which can be reflected on cortical EEG, the BIS™ has also been used to assess the adequacy of analgesia.4Guignard B Menigaux C Dupont X Fletcher D Chauvin M The effect of remifentanil on the bispectral index change and hemodynamic responses after orotracheal intubation.Anesth Analg. 2000; 90: 161-167Crossref PubMed Scopus (282) Google Scholar The BIS™ is a complex and not completely accessible parameter established to statistically quantify the hypnotic effect of propofol.3Kearse Jr, LA Manberg P Chamoun N deBros F Zaslavsky A Bispectral analysis of the electroencephalogram correlates with patient movement to skin incision during propofol/nitrous oxide anesthesia.Anesthesiology. 1994; 81: 1365-1370Crossref PubMed Scopus (181) Google Scholar It was further found able to discriminate hypnotic levels induced by isoflurane and midazolam, albeit with less precision.5Glass PS Bloom M Kearse L Rosow C Sebel P Manberg P Bispectral analysis measures sedation and memory effects of propofol, midazolam, isoflurane, and alfentanil in healthy volunteers.Anesthesiology. 1997; 86: 836-847Crossref PubMed Scopus (1105) Google Scholar However, 'depth of anaesthesia' monitors based on the EEG have demonstrated their usefulness in allowing adjustments of drug delivery to individual needs in clinical practice, decreasing both the risks of overdosing and of awareness, and slightly decreasing the recovery time.6Punjasawadwong Y Boonjeungmonkol N Phongchiewboon A Bispectral index for improving anaesthetic delivery and postoperative recovery.Cochrane Database Syst Rev. 2007; : CD003843PubMed Google Scholar Liu and colleagues7Liu N Le Guen M Boichut N et al.Nitrous oxide does not produce a clinically important sparing effect during close-loop delivered propofol–remifentanil anaesthesia guided by the bispectral index: a randomized multicentre study.Br J Anaesth. 2014; 112: 842-851Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar consider the sparing effect of nitrous oxide (N2O) on propofol and remifentanil consumptions when those drugs are administered through a closed-loop system using the BIS™ as the control parameter. They do not find any clinically significant difference in propofol or remifentanil consumption whether or not nitrous oxide is added to the inhaled mixture. Liu and colleagues' system uses the BIS™ to control both propofol and remifentanil administrations, the hypnotic being driven by progressive changes in the parameter, and the opioid by rapid changes seemingly corresponding to arousal reactions. They claim that their system, being independent from the clinician, is more reliable to detect any difference induced by nitrous oxide administration than all the other studies published so far which were based on haemodynamic and clinical observation. However, no other descriptors of 'adequacy of anaesthesia' are considered in their system. Nitrous oxide has actually initiated the era of modern anaesthesia more than 150 yr ago, when it was used in dental surgery. It has a weak sedative action, with a minimum alveolar concentration (MAC) around 1.04 (0.10) (se) atm absolute, measured in hyperbaric conditions,8Hornbein TF Eger II, EI Winter PM Smith G Wetstone D Smith KH The minimum alveolar concentration of nitrous oxide in man.Anesth Analg. 1982; 61: 553-556Crossref PubMed Scopus (152) Google Scholar and may provoke loss of consciousness through a mechanism called dissociative anaesthesia, similar to that obtained with ketamine, both agents acting through the N-methyl-d-aspartate (NMDA) receptor.9Sleigh JW Barnard JP Entropy is blind to nitrous oxide. Can we see why?.Br J Anaesth. 2004; 92: 159-161Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar However, nitrous oxide is nowadays mainly considered as an analgesic. As such, it reduces the amount of both volatile and propofol required to blunt motor responses to skin incision (MAC, EC50) by about 30%.10Davidson JA Macleod AD Howie JC White M Kenny GN Effective concentration 50 for propofol with and without 67% nitrous oxide.Acta Anaesthesiol Scand. 1993; 37: 458-464Crossref PubMed Scopus (100) Google Scholar 11Torri G Damia G Fabiani ML Effect on nitrous oxide on the anaesthetic requirement of enflurane.Br J Anaesth. 1974; 46: 468-472Abstract Full Text PDF PubMed Scopus (31) Google Scholar The influence of nitrous oxide on the central nervous system is very complex. Conversely to GABA-ergic hypnotics which induce mainly cortical EEG depression (i.e. slowing and synchronization preceding burst suppression), nitrous oxide, antagonist of the NMDA receptor, also stimulates the EEG and increases fast frequencies activity (>30 Hz), specially in the frontal area.12Foster BL Liley DT Nitrous oxide paradoxically modulates slow electroencephalogram oscillations: implications for anesthesia monitoring.Anesth Analg. 2011; 113: 758-765Crossref PubMed Scopus (31) Google Scholar 13Yamamura T Fukuda M Takeya H Goto Y Furukawa K Fast oscillatory EEG activity induced by analgesic concentrations of nitrous oxide in man.Anesth Analg. 1981; 60: 283-288Crossref PubMed Scopus (53) Google Scholar This activation occurs early after introducing nitrous oxide and is associated with phase coupling peaks around 4 Hz (delta) and 10 Hz (spindle).14Hagihira S Takashina M Mori T Mashimo T The impact of nitrous oxide on electroencephalographic bicoherence during isoflurane anesthesia.Anesth Analg. 2012; 115: 572-577PubMed Google Scholar Thereafter, fast frequency activity decreases unmasking low frequencies activity.15Rampil IJ Kim JS Lenhardt R Negishi C Sessler DI Bispectral EEG index during nitrous oxide administration.Anesthesiology. 1998; 89: 671-677Crossref PubMed Scopus (153) Google Scholar For intermediate duration administration or concentrations, both effects may neutralize and EEG-derived parameters may show no change. Moreover, nitrous oxide also acts at the spinal level, where it stimulates superficial neurones and depresses deep neurones,16Antognini JF Atherley RJ Laster MJ Carstens E Dutton RC Eger II, EI A method for recording single unit activity in lumbar spinal cord in rats anesthetized with nitrous oxide in a hyperbaric chamber.J Neurosci Methods. 2007; 160: 215-222Crossref PubMed Scopus (3) Google Scholar and at the midbrain level to modulate ascendant nociceptive inputs17Shafer SL Hendrickx JF Flood P Sonner J Eger II, EI Additivity versus synergy: a theoretical analysis of implications for anesthetic mechanisms.Anesth Analg. 2008; 107: 507-524Crossref PubMed Scopus (50) Google Scholar and stimulate reticular neurones. As all single EEG-derived parameters, BIS™ is unable to describe all these complex phenomena. It is recorded through a single frontal sensor, and therefore will catch accurately frontal changes but neither alterations in other territories such as the parietal area which is deeply depressed by nitrous oxide nor changes in the parietal/frontal equilibrium.18Kuhlmann L Foster BL Liley DT Modulation of functional EEG networks by the NMDA antagonist nitrous oxide.PLoS One. 2013; 8: e56434Crossref PubMed Scopus (24) Google Scholar To limit EMG and environment artifacts, BIS™ signal processing is filtered at 32 Hz (as State Entropy and PSI). It may therefore miss fast frequency peaks, and appear 'blind' to nitrous oxide effect if predominant in fast frequencies. Laboratory (volunteers) studies were able to describe accurately nitrous oxide effects because they could record EEG in a quiet noise-free environment which is certainly not the case in an operating theatre. Lastly, spinal and midbrain effects of nitrous oxide, particularly relevant to the analgesic component of anaesthesia are not directly displayed on cortical EEG whatever the analysis technique used. Clinical results illustrate these limitations. Quite a few clinical works have studied the influence of nitrous oxide on BIS™ values before and during surgery and their results are deeply confusing. When nitrous oxide 70% was used as the sole hypnotic administered to healthy volunteers, it induced loss of consciousness without modifying the BIS™, in contrast with what was observed with sevoflurane.19Barr G Jakobsson JG Owall A Anderson RE Nitrous oxide does not alter bispectral index: study with nitrous oxide as sole agent and as an adjunct to i.v. anaesthesia.Br J Anaesth. 1999; 82: 827-830Abstract Full Text PDF PubMed Scopus (163) Google Scholar In another study including 48 patients with epidural analgesia, inhalation of increasing nitrous oxide concentrations resulted in a progressive reduction in the OAA/S without corresponding decrease in BIS™ values.20Park KS Hur EJ Han KW Kil HY Han TH Bispectral index does not correlate with observer assessment of alertness and sedation scores during 0.5% bupivacaine epidural anesthesia with nitrous oxide sedation.Anesth Analg. 2006; 103 (table of contents): 385-389Crossref PubMed Scopus (39) Google Scholar Similar results were observed with cerebral state index (CSI)21Anderson RE Barr G Jakobsson JG Cerebral state index during anaesthetic induction: a comparative study with propofol or nitrous oxide.Acta Anaesthesiol Scand. 2005; 49: 750-753Crossref PubMed Scopus (35) Google Scholar and Entropy.22Anderson RE Jakobsson JG Entropy of EEG during anaesthetic induction: a comparative study with propofol or nitrous oxide as sole agent.Br J Anaesth. 2004; 92: 167-170Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar During sevoflurane anaesthesia titrated on BIS™ (40–60), adding nitrous oxide consistently decreased BIS™ and Entropy23Hans P Bonhomme V Benmansour H Dewandre PY Brichant JF Lamy M Effect of nitrous oxide on the bispectral index and the 95% spectral edge frequency of the electroencephalogram during surgery.Anaesthesia. 2001; 56: 999-1002Crossref PubMed Scopus (20) Google Scholar 24Ozcan MS Ozcan MD Khan QS Thompson DM Chetty PK Does nitrous oxide affect bispectral index and state entropy when added to a propofol versus sevoflurane anesthetic?.J Neurosurg Anesthesiol. 2010; 22: 309-315Crossref PubMed Scopus (20) Google Scholar with the deepening of anaesthesia. This decrease was not observed with propofol,24Ozcan MS Ozcan MD Khan QS Thompson DM Chetty PK Does nitrous oxide affect bispectral index and state entropy when added to a propofol versus sevoflurane anesthetic?.J Neurosurg Anesthesiol. 2010; 22: 309-315Crossref PubMed Scopus (20) Google Scholar possibly because propofol inhibited reticular neurones, whereas sevoflurane did not. During gynaecological surgery with very low dose of alfentanil given at induction, adding nitrous oxide allowed decreasing the amount of sevoflurane necessary to maintain a chosen MPF (2–3 Hz) linearly with nitrous oxide fraction.25Ropcke H Schwilden H Interaction of isoflurane and nitrous oxide combinations similar for median electroencephalographic frequency and clinical anesthesia.Anesthesiology. 1996; 84: 782-788Crossref PubMed Scopus (26) Google Scholar During a deeper sevoflurane anaesthesia (BIS™ ∼35), adding nitrous oxide slightly decreased BIS™, markedly decreased State Entropy but left PSI unchanged.26Soto RG Smith RA Zaccaria AL Miguel RV The effect of addition of nitrous oxide to a sevoflurane anesthetic on BIS, PSI, and entropy.J Clin Monit Comput. 2006; 20: 145-150Crossref PubMed Scopus (15) Google Scholar During an isoflurane anaesthesia deep enough to achieve burst suppression, adding nitrous oxide decreased the burst suppression ratio and seemed to lighten anaesthesia.27Yli-Hankala A Lindgren L Porkkala T Jantti V Nitrous oxide-mediated activation of the EEG during isoflurane anaesthesia in patients.Br J Anaesth. 1993; 70: 54-57Abstract Full Text PDF PubMed Scopus (45) Google Scholar Several mechanisms have been proposed, such as an increase in cerebral blood flow or an activation of reticular neurones counteracting the effect on cortical neurones.27Yli-Hankala A Lindgren L Porkkala T Jantti V Nitrous oxide-mediated activation of the EEG during isoflurane anaesthesia in patients.Br J Anaesth. 1993; 70: 54-57Abstract Full Text PDF PubMed Scopus (45) Google Scholar After a noxious stimulation such as intubation, paradoxical BIS™ and SEF decreases have been observed in the presence of nitrous oxide, but this effect disappeared when an opioid bolus was added.28Oda Y Tanaka K Matsuura T Hase I Nishikawa K Asada A Nitrous oxide induces paradoxical electroencephalographic changes after tracheal intubation during isoflurane and sevoflurane anesthesia.Anesth Analg. 2006; 102: 1094-1102Crossref PubMed Scopus (14) Google Scholar In another study, nitrous oxide inhibited both BIS™ changes during intubation and clinical response (isolated forearm) suggesting that an adequate level of analgesia had been achieved.29Coste C Guignard B Menigaux C Chauvin M Nitrous oxide prevents movement during orotracheal intubation without affecting BIS value.Anesth Analg. 2000; 91: 130-135PubMed Google Scholar In summary, the effect of nitrous oxide on EEG and EEG-derived parameters during anaesthesia is only one of all nitrous oxide pharmacodynamic effects, along with sedation, immobility, or haemodynamic control. It depends on both excitation/depression and cortical/subcortical balances. These balances vary with the associated drugs (volatile vs propofol), on the degree of EEG depression, and on the nociception/antinociception equilibrium. The results achieved by Liu and colleagues,7Liu N Le Guen M Boichut N et al.Nitrous oxide does not produce a clinically important sparing effect during close-loop delivered propofol–remifentanil anaesthesia guided by the bispectral index: a randomized multicentre study.Br J Anaesth. 2014; 112: 842-851Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar titrating anaesthesia entirely on a single EEG parameter, confirm a small influence of nitrous oxide to maintain a chosen value of this surrogate parameter through dosing of GABA-ergic drugs. These authors were unable to demonstrate any influence on the level of sedation in the absence of stimulation, because nitrous oxide was introduced after intubation, at a time when the doses required for surgery were far above those required for loss of consciousness. Moreover, considering control over adrenergic stimuli, one may even suspect that both groups were not at the same depth of analgesia (despite similar BIS™), since the incidence of movement was divided by three in the nitrous oxide group, and the incidence of antihypertensive medication by two. At a time when instrumental monitoring is more and more prominent in our anaesthesia practice, this work is a useful reminder of the fact that a mathematical construction based on cortical EEG may not (yet?) include all the complexity surrounding pharmacological loss of consciousness and control over adrenergic stimuli, and thus be unable to completely describe anaesthesia. The future of drug adjustments might well include more complex algorithms combining surrogate measures of sedation (EEG), surrogate measures of analgesia (i.e. pupil dilatation reflex),30Oka S Chapman CR Kim B Nakajima I Shimizu O Oi Y Pupil dilation response to noxious stimulation: effect of varying nitrous oxide concentration.Clin Neurophysiol. 2007; 118: 2016-2024Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar and clinical signs considered in their surgical context. None declared. BIS™Bispectral index of EEG including bispectrum, quasi burst, and β ratio.SEFSpectral edge frequency. Frequency of the spectrum below which are gathered 95% of the frequency components of an EEG epoch.MPFMedian power frequency is the frequency of the spectrum below which are gathered 50% of the frequency components of an EEG epoch.EntropyThis returns two indexes both expressing the irregularity, complexity, or unpredictability characteristics of EEG signal: state entropy (including frequencies from 0.5 to 32 Hz) and response entropy.Patient state indexQ EEG-derived parameter including EEG power, frequency, and phase information from anterior–posterior relationships of the brain and coherence between bilateral brain regions. Bispectral index of EEG including bispectrum, quasi burst, and β ratio. Spectral edge frequency. Frequency of the spectrum below which are gathered 95% of the frequency components of an EEG epoch. Median power frequency is the frequency of the spectrum below which are gathered 50% of the frequency components of an EEG epoch. This returns two indexes both expressing the irregularity, complexity, or unpredictability characteristics of EEG signal: state entropy (including frequencies from 0.5 to 32 Hz) and response entropy. Q EEG-derived parameter including EEG power, frequency, and phase information from anterior–posterior relationships of the brain and coherence between bilateral brain regions.

En Francia, por ejemplo, cada año se practican alrededor de 2 millones de endoscopias digestivas con la participación de un equipo de anestesia. La mayoría de las veces se trata de actos ambulatorios de baja morbilidad, pero en ocasiones se efectúan en pacientes hospitalizados muy ancianos y/o de clase ASA (American Society of Anesthesiology) elevada. Las necesidades de sedación para una endoscopia alta diagnóstica se presentan en alrededor del 40% de los pacientes. La exigencia de un anestesista para practicar la sedación difiere según el país. La colangiografía retrógrada se efectúa en decúbito lateral o prono y necesita una sedación profunda para asegurar que el paciente permanezca inmóvil. La intubación es rara vez necesaria, pero la medida del CO2 espirado, que además permite vigilar la frecuencia respiratoria, es muy recomendable. En la colonoscopia, el anestesista tiene libre acceso a la cabeza y las vías respiratorias. Por lo tanto, todos los protocolos anestésicos son posibles. El anestesista debe saber adaptar la técnica al paciente y a las condiciones locales. El principal agente anestésico es el propofol, en el mejor de los casos administrado mediante infusión intravenosa con objetivo de concentración (AIVOC), pero se están realizando estudios de evaluación del remifentanilo en AIVOC para esta indicación. Las endoscopias digestivas rara vez producen complicaciones, pero de haberlas suelen deberse a la hipoxia, razón por la cual conviene administrar oxígeno al paciente en todos los casos. Sin embargo, esto puede enmascarar la depresión respiratoria de forma prolongada, lo que refuerza el interés de vigilar el CO2 espirado y la frecuencia respiratoria. El 13% de los pacientes se encuentra bajo tratamiento a largo plazo con anticoagulantes y/o antiagregantes plaquetarios (AAP). En las endoscopias con riesgo hemorrágico bajo (incluidas las biopsias) no es necesario interrumpir la administración de antivitaminas K (AVK) o AAP.

PURPOSE OF REVIEW:To assess the influence of antiplatelet drugs (APDs) in outpatients' perioperative care and to propose up-to-date management of those patients.RECENT FINDINGS:Evidence is spreading on the risk of adverse cardiovascular events (ACEs) when APD therapy is discontinued, specifically in patients with coronary stents. Conversely, maintaining such treatments throughout the operative period appears usually safe. Bridging with low-molecular-weight heparins poorly protects against ACEs. In outpatients, major surgical bleeding is rare, but sometimes a minor hemorrhage may jeopardize the success of a surgical procedure. Despite the paucity of properly sized randomized trials in this setting, recommendations have been issued by scientific societies and can be used as guidelines. Variability in APD efficiency is now better appraised, and research on versatile bedside testing of platelet function is active. New drugs are expected to be launched in the near future, all this aiming at improving individualized drug dosage and therefore both safety and efficiency of APD therapies.SUMMARY:In surgical patients APD therapy should be maintained in all situations in which the risk of surgical bleeding is low, which is usually the case in the ambulatory setting. In clearly identified cases in which bleeding might threaten either the patient's life or the success of the surgical procedure in patients at high risk of ACE, the discontinuation protocol must be established in conjunction with the cardiologist and the APD therapy resumed as soon as possible. Bridging with low-molecular-weight heparins is not recommended.

Purpose of review This review is intended to provide an update on pharmacology of hypnotic drugs and current state of published research for new or improved agents. Recent findings Albeit no completely new drugs have been launched in the last few years, research on pharmacology of existing drugs is still ongoing, and new formulations of existing drugs are proposed (propofol, isoflurane). Xenon, an old but so far unavailable drug, has elicited new interests and this review will examine the recent publications on this fascinating agent. Summary These results will improve our handling of existing drugs and open new perspectives on drug monitoring through measurement of propofol concentrations in expired air.

Si l'espérance de vie augmente en France (82,5 ans en moyenne), l'espérance de vie en bonne santé est d'environ 20 ans de moins. Ces chiffres sont stables depuis 10 ans. Le vieillissement est un processus naturel qui s'accompagne de douleurs chroniques ou aiguës, ayant un retentissement sur la qualité de vie. La population âgée présente des situations variables en matière de santé, mais dont la douleur est souvent une constante. La douleur physique altère la qualité de vie et peut modifier un état général souvent précaire. De plus, l'âge est à l'origine de changements physiologiques et psychologiques. Des changements pharmacocinétiques et pharmacodynamiques compliquent l'utilisation de certains médicaments antalgiques. L'âge est aussi confronté à la maladie cancéreuse où la douleur est omniprésente. Certaines pathologies, comme le diabète et l'artérite, sont à l'origine de lésions cutanées des membres inférieurs. Enfin, la polymédication des personnes âgées, liée à la multiplication des pathologies du vieillissement, complique leur prise en charge. L'anesthésie locorégionale à visée analgésique, par cathéter périnerveux de longue durée, permet un soulagement puissant et efficace de la douleur, sans interférer avec les autres médicaments. Elle s'adapte aux modifications physiologiques du vieillissement. Elle permet aux soignants de faire des pansements sans douleur, améliorant ainsi la qualité des soins et la qualité de vie des patients. La suppression des réseaux de santé en 2019 nécessite l'intervention de prestataires de santé. Malgré leur efficacité et leur innocuité, ces techniques sont encore confidentielles à domicile du fait d'une législation en retard.While life expectancy is increasing in France (82.5 years on average), life expectancy in good health is around 20 years less. These figures have been stable for 10 years. Aging is a natural process that is accompanied by chronic or acute pain, having an impact on the quality of life. The elderly population presents variable health situations, but pain is often a constant. Physical pain affects the quality of life and can change an often precarious general condition. In addition, age is the cause of physiological and psychological changes. Pharmacokinetic and pharmacodynamic changes complicate the use of some analgesic drugs. Age is also faced with cancerous disease where pain is omnipresent. Certain pathologies, such as diabetes and arteritis, cause skin lesions in the lower limbs. Finally, the poly-medication of the elderly linked to the multiplication of aging pathologies complicates their management. Locoregional analgesic anesthesia, via a long-lasting peri-nerve catheter, provides powerful and effective pain relief without interfering with other medications. It adapts to the physiological changes of aging. It allows caregivers to make dressings without pain, thus improving the quality of care and the quality of life of patients. The elimination of health networks in 2019 requires the intervention of health providers. Despite their effectiveness and harmlessness, these techniques are still confidential at home due to backlogged legislation.

Most opioids used in anaesthesia are of the anilidopiperidine family, including fentanyl, alfentanil, sufentanil and remifentanil. While all share similar pharmacological properties, remifentanil, the newest one, is probably the most original, which is the reason this review focusses especially on this drug. Remifentanil is a potent μ-agonist that retains all the pharmacodynamic characteristics of its class (regarding analgesia, respiratory depression, muscle rigidity, nausea and vomiting, pruritus, etc.) but with a unique pharmacokinetic profile that combines a short onset and the fastest offset, independent of the infusion duration. Consequently, it offers a unique titratability when its effects need to be quickly achieved or suppressed, but it requires specific drug delivery schemes such as continuous infusion, target-controlled infusion and anticipated postoperative pain treatment. Kinetic differences between opioids used in anaesthesia and some clinical uses of remifentanil are reviewed in this chapter.

PURPOSE OF REVIEW:Remifentanil has now reached maturity, as reflected by the increasing number of clinical papers relating to its use. Its position among anaesthetic drugs is now better understood, and this review will attempt to place it in the context of current clinical practice.RECENT FINDINGS AND SUMMARY:Propofol reduces the initial distribution of remifentanil, leading to higher concentrations during induction. Propofol and remifentanil administered together at sedative doses display a major synergistic interaction on the respiratory drive. Remifentanil accelerates the penetration of sevoflurane to its site of effect. The risk of intraoperative awareness seems to be low when remifentanil is associated to very low concentrations of hypnotic drugs, but this field warrants further investigation. Acute tolerance to opioids and its prevention remain controversial.SUMMARY:Remifentanil is the opioid of choice for tracheal intubation without muscle relaxants. It provides an alternative to regional anaesthesia in labour pain control. Target-controlled infusion may further improve the administration of remifentanil.

Elderly patient care represents a growing part of the medical activity in developed countries. It is important to define the specificities of this heterogeneous population, first of all to improve patient care, but also to dispatch human and financial resources more effectively by assessing the relative risks and benefits of invasive treatments. All these concerns are well-reflected by the recently published papers in this field: demographic and outcome studies; basic science papers designed to improve our knowledge of normal ageing processes; and more clinical studies specifically on drug use in the elderly.