Desflurane consumption during automated closed-circuit delivery is higher than when a conventional anesthesia machine is used with a simple vaporizer-O2-N2O fresh gas flow sequence

The Zeus® (Dräger, Lübeck, Germany), an automated closed-circuit anesthesia machine, uses high fresh gas flows (FGF) to wash-in the circuit and the lungs, and intermittently flushes the system to remove unwanted N₂. We hypothesized this could increase desflurane consumption to such an extent that agent consumption might become higher than with a conventional anesthesia machine (Anesthesia Delivery Unit [ADU®], GE, Helsinki, Finland) used with a previously derived desflurane-O₂-N₂O administration schedule that allows early FGF reduction.Journal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Pain management: physiopathology, future research and endpoints.

In this article, first, the different stages of acquisition and processing of nociceptive information from peripheral receptor to brain are reviewed and the plastic changes that accompany tissue injury are underlined. For instance, the subclassification of peripheral receptors in nociceptors and non-nociceptors (e.g. mechanoreceptors, thermoreceptors) must be understood in the light of peripheral sensitization. This phenomenon is the probable explanation for primary hyperalgesia, the decrease in pain threshold at the site of injury. The observation that substance P enhances N-methyl-D-aspartate (NMDA)-elicited responses suggests that these two receptors may operate in concert to prolong and amplify the afferent input generated by peripheral tissue injury. Such afferent barrage induces a state of central sensitization. Second, the major problems in the management of cancer pain, i.e. the development of tolerance to opioids and opioid-insensitive pain, are discussed. The loss of drug effect observed after chronic exposure of the opioid receptor (tolerance) may be the consequence of the down-regulation or desensitization phenomenon (where the total number of receptors coupled to the second messenger is reduced). The agonist dose-response begins to shift to the right. The dramatic analgesic improvement obtained with subanaesthetic doses of ketamine, an NMDA receptor antagonist, in those of our cancer patients who have become resistant to morphine is intriguing. As shown for tolerance, insensitivity to opioids may represent a rightward shift in the opioid dose-response curve and the analgesic effect of ketamine the reversal of that shift.Journal ArticleReviewSCOPUS: re.jinfo:eu-repo/semantics/publishe

Contribution à l'étude de l'analgésie spinale: rôle des récepteurs à l'adenosine et phénomène de tolérance aux opiacés, in vivo chez le rat

Doctorat en sciences médicalesinfo:eu-repo/semantics/nonPublishe

Differential cross-tolerance between intrathecal morphine and sufentanil in the rat.

By means of a subcutaneously implanted osmotic pump, groups of rats received a constant-rate (1 microliter/h), 7-day intrathecal infusion of saline or one of two mu opioid agonists: sufentanil (0.6 nmol/h) or morphine (20 nmol/h). These concentrations of morphine and sufentanil yielded a comparable near maximal hot-plate response latency on day 1 of the infusion. On day 7, the magnitude of tolerance was assessed in each group by establishing intrathecal dose-response curves and ED50 values for sufentanil and morphine given as a bolus injection. Each infused animal was used for a single bolus injection. In all cases, infusion with the opioid resulted in a rightward shift (increase in ED50) for both morphine and sufentanil as compared to saline-infused animals. The magnitude of the shift, however, was different for the two drugs. Thus in morphine-infused rats, the morphine ED50 increased as compared to saline-infused animals by a factor of 44, whereas the sufentanil ED50 shifted by a factor of 10. In sufentanil-infused animals, the respective shifts in the morphine and sufentanil ED50 values were increased by a factor of 9 and 3, respectively. Thus, a significantly greater shift as compared to saline-infused animals was observed in morphine-infused than in sufentanil-infused animals. Conversely, regardless of the opioid to which the animal was exposed, morphine-tested animals showed a greater rightward shift than did sufentanil-tested animals.(ABSTRACT TRUNCATED AT 250 WORDS)Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, P.H.S.info:eu-repo/semantics/publishe

Spinal administration of receptor-selective drugs as analgesics: new horizons.

The processing at the spinal cord levels of sensory information is subject to modulation by a number of local receptor systems, including opioids: alpha 2 adrenergic; and to a lesser extent serotonin, GABAB, neuropeptide Y, cholinergic, adenosine, and the NMDA-glutamate site. The functional utility of these multiple systems are only partially understood, but it appears that (a) they may act individually to alter different aspects of the nociceptive sensory message (b) they could be used synergistically to reduce the incidence of side effects by reducing the dose of agents required to yield analgesic effects, and (c) they may function variably in animals made tolerant to classes of receptor agonists.Journal ArticleReviewSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Role of spinal adenosine receptors in modulating the hyperesthesia produced by spinal glycine receptor antagonism.

The intrathecal administration of strychnine in rats yields a prominent touch-evoked allodynia. The effects of an intrathecally administered A1 adenosine agonist: N6-(L-2-phenylisopropyl)-adenosine (LPIA) or an A2 adenosine agonist: 5'-(N-ethyl carboxamido)-adenosine (NECA), on this touch-evoked hyperesthesia were examined. Over the range of 0.3-1.0 nmol these agents produced a dose-dependent inhibition of the strychnine-evoked hyperesthesia. This inhibition was reversed following intraperitoneal injection of caffeine, an adenosine receptor antagonist. No statistical differences between LPIA and NECA were recorded. The powerful effect of adenosine analogues on strychnine hyperesthesia occur at doses that have only a mild analgesic effect on the thermally evoked hot-plate response. This effect is in contrast to opioids, which have been reported to be only minimally effective against strychnine-evoked hyperesthesia. The characteristics of the strychnine hyperesthesia appear to mimic the clinical phenomenon observed in patients suffering from sensory dysesthesia following nerve injury and suggest a possible role for the adenosine receptor in certain pain states.Journal ArticleResearch Support, U.S. Gov't, P.H.S.info:eu-repo/semantics/publishe

The role of spinal and brainstem adenosine receptors in the modulation of the volume-evoked micturition reflex in the unanesthetized rat.

The pharmacology of the spinal, supraspinal and peripheral adenosine receptor subtypes (A1, A2) and their influence on the volume-evoked micturition reflex (VEMR) was studied in a chronic unanesthetised rat model by cystometrography after intrathecal (i.t.), intracerebroventricular (i.c.v.) and intravenous (i.v.) injection. Intrathecally administered A1 adenosine agonist: N6-(L-2-phenylisopropyl)adenosine (R-PIA) and A2 adenosine agonist: 5'-(N-ethylcarboxamido)adenosine (NECA) were equally active with 1.0 nmol reliably producing an increase in the volume necessary to induce the VEMR. At a higher dose (3 nmol), a long-lasting blockade of the VEMR was produced by both agonists. These effects were reversed following intraperitoneal injection of caffeine, an adenosine antagonist. This inhibition of the VEMR outlasted the spinal antinociceptive action which we have previously reported for these two agonists. Contrary to the spinal effect of these agonists, i.c.v. (0.3-3 nmol) and i.v. (100-1000 nmol) injections of R-PIA and NECA resulted in a significant decrease in the volume required to evoke the VEMR. We conclude that at the spinal level a xanthine-sensitive adenosine receptor(s) inhibits the VEMR. Based on several indirect lines of evidence, we speculate that these effects are not mediated by an action on primary afferent input or directly on preganglionic neurons, but on an excitatory interneuronal link.Journal Articleinfo:eu-repo/semantics/publishe

Le traitement des céphalées après ponction lombaire.

Journal Articleinfo:eu-repo/semantics/publishe

Receptors, Neuropathways, Mechanisms.

info:eu-repo/semantics/publishe

Perioperative acute coronary syndrome during functional endoscopic sinus surgery in a young HIV-infected patient. A case report.

We report a case of a young HIV-infected woman treated for more than ten years by highly active antiretroviral therapy, presenting a peroperative acute coronary syndrome caused by a hypertensive episode after systemic resorption of locally applied epinephrine during a functional endoscopic sinus surgery. Since patients with multiple risk factors for coronary artery desease seems to be more susceptible to complications of epinephrine injection, this reminds us of the higher cardiovascular risk for HIV patients with long term treatment. Therefore anesthesiologists should be susceptible to consider specifically the pre- and postoperative evaluation of patients with long term antiretroviral therapy.Case ReportsJournal Articleinfo:eu-repo/semantics/publishe