Maintaining the communication and information tool of the Belgian anesthesiology community
in Acta Anaesthesiologica Belgica (2011), 62(4), 173-174Detailed reference viewed: 13 (0 ULg)
Influence of anesthesia on cerebral blood flow, cerebral metabolic rate, and brain functional connectivity.
BONHOMME, Vincent ; BOVEROUX, Pierre ; HANS, Pol et al
in Current Opinion in Anaesthesiology (2011), 24(5), 474-9
PURPOSE OF REVIEW: To describe recent studies exploring brain function under the influence of hypnotic anesthetic agents, and their implications on the understanding of consciousness physiology and ... [more ▼]
PURPOSE OF REVIEW: To describe recent studies exploring brain function under the influence of hypnotic anesthetic agents, and their implications on the understanding of consciousness physiology and anesthesia-induced alteration of consciousness. RECENT FINDINGS: Cerebral cortex is the primary target of the hypnotic effect of anesthetic agents, and higher-order association areas are more sensitive to this effect than lower-order processing regions. Increasing concentration of anesthetic agents progressively attenuates connectivity in the consciousness networks, while connectivity in lower-order sensory and motor networks is preserved. Alteration of thalamic sub-cortical regulation could compromise the cortical integration of information despite preserved thalamic activation by external stimuli. At concentrations producing unresponsiveness, the activity of consciousness networks becomes anticorrelated with thalamic activity, while connectivity in lower-order sensory networks persists, although with cross-modal interaction alterations. SUMMARY: Accumulating evidence suggests that hypnotic anesthetic agents disrupt large-scale cerebral connectivity. This would result in an inability of the brain to generate and integrate information, while external sensory information is still processed at a lower order of complexity. [less ▲]Detailed reference viewed: 56 (12 ULg)
Unexpected entropy response to saline spraying at the end of posterior fossa surgery: a few cases report.
; BONHOMME, Vincent ; et al
in Acta anaesthesiologica Belgica (2011), 62(2), 87-90
The Spectral Entropy proposed to monitor the depth of anesthesia includes the State Entropy (SE) computed from the EEG (0.8-32 Hz frequency band), and the Response Entropy (RE) computed from EEG and ... [more ▼]
The Spectral Entropy proposed to monitor the depth of anesthesia includes the State Entropy (SE) computed from the EEG (0.8-32 Hz frequency band), and the Response Entropy (RE) computed from EEG and facial muscles activity (0.5-47 Hz frequency band). We report an unexpected Entropy response to saline spraying at the end of posterior fossa surgery. Six patients undergoing scheduled functional surgery of the posterior fossa were included in this report. They were anesthetized with propofol and remifentanil using TCI and received an intubation dose of rocuronium. At the end of surgery, saline spraying, performed for hemostatic purpose and wreckage elimination, resulted in a sustained increase in RE and SE without hemodynamic modification in four patients, while no change was observed in the two other ones. In one of the responding patients, 0.1 mg kg(-1) rocuronium attenuated the Entropy response. In the two non responders, repetition of spraying or rocuronium administration did not change Entropy value. Recovery from anesthesia was comparable in all patients and none of them complained from awareness. We conclude that Entropy can increase during posterior fossa surgery in non-paralyzed patients. This response probably reflects an increase in facial muscle activity rather than a change in depth of anesthesia, as far as it can be attenuated by a small dose of rocuronium. While this hypothesis requires further investigation, these observations suggest that saline spraying may confound interpretation of Entropy during posterior fossa surgery. [less ▲]Detailed reference viewed: 82 (4 ULg)
Intravenous lidocaine infusion reduces bispectral index-guided requirements of propofol only during surgical stimulation.
Hans, Grégory ; Lauwick, Séverine ; Kaba, Abdourahmane et al
in British Journal of Anaesthesia (2010), 105(4), 471-9
BACKGROUND: I.V. lidocaine reduces volatile anaesthetics requirements during surgery. We hypothesized that lidocaine would also reduce propofol requirements during i.v. anaesthesia. METHODS: A randomized ... [more ▼]
BACKGROUND: I.V. lidocaine reduces volatile anaesthetics requirements during surgery. We hypothesized that lidocaine would also reduce propofol requirements during i.v. anaesthesia. METHODS: A randomized controlled study of 40 patients tested the effect of i.v. lidocaine (1.5 mg kg(-1) then 2 mg kg(-1) h(-1)) on propofol requirements. Anaesthesia was maintained with remifentanil and propofol target-controlled infusions (TCI) to keep the bispectral index (BIS) around 50. Effect-site concentrations of propofol and remifentanil and BIS values were recorded before and after skin incision. Data were analysed using anova and mixed effects analysis with NONMEM. Two dose-response studies were then performed with and without surgical stimulation. Propofol TCI titrated to obtain a BIS around 50 was kept constant. Then patients were randomized into four groups: A, saline; B, 0.75 mg kg(-1) bolus then infusion 1 mg kg(-1) h(-1); C, 1.5 mg kg(-1) bolus and infusion 2 mg kg(-1) h(-1); and D, 3 mg kg(-1) bolus and infusion 4 mg kg(-1) h(-1). Lidocaine administration coincided with skin incision. BIS values and haemodynamic variables were recorded. Data were analysed using linear regression and two-way anova. RESULTS: Lidocaine decreased propofol requirements (P<0.05) only during surgery. In the absence of surgical stimulation, lidocaine did not affect BIS nor haemodynamic variables, whereas it reduced BIS increase (P=0.036) and haemodynamic response (P=0.006) secondary to surgery. CONCLUSIONS: The sparing effect of lidocaine on anaesthetic requirements seems to be mediated by an anti-nociceptive action. [less ▲]Detailed reference viewed: 68 (4 ULg)
Sevoflurane facial mask induction in children: using two different techniques end to comparable intubation conditions but different Bispectral Index values
Dabee, Loïc ; Hallet, Claude ; Venneman, Ingrid et al
in Acta Anaesthesiologica Belgica (2010, June 19), 61(2), 94Detailed reference viewed: 38 (0 ULg)
User-independent calculation of resting state connectivity patterns in Propofol sedated subjects.
Guldenmund, Justus Pieter ; BOVEROUX, Pierre ; VANHAUDENHUYSE, Audrey et al
Poster (2010)Detailed reference viewed: 7 (3 ULg)
Breakdown of within- and between-network resting state functional magnetic resonance imaging connectivity during propofol-induced loss of consciousness.
Boveroux, Pierre ; Vanhaudenhuyse, Audrey ; Bruno, Marie-Aurélie et al
in Anesthesiology (2010), 113(5), 1038-53
BACKGROUND: Mechanisms of anesthesia-induced loss of consciousness remain poorly understood. Resting-state functional magnetic resonance imaging allows investigating whole-brain connectivity changes ... [more ▼]
BACKGROUND: Mechanisms of anesthesia-induced loss of consciousness remain poorly understood. Resting-state functional magnetic resonance imaging allows investigating whole-brain connectivity changes during pharmacological modulation of the level of consciousness. METHODS: Low-frequency spontaneous blood oxygen level-dependent fluctuations were measured in 19 healthy volunteers during wakefulness, mild sedation, deep sedation with clinical unconsciousness, and subsequent recovery of consciousness. RESULTS: Propofol-induced decrease in consciousness linearly correlates with decreased corticocortical and thalamocortical connectivity in frontoparietal networks (i.e., default- and executive-control networks). Furthermore, during propofol-induced unconsciousness, a negative correlation was identified between thalamic and cortical activity in these networks. Finally, negative correlations between default network and lateral frontoparietal cortices activity, present during wakefulness, decreased proportionally to propofol-induced loss of consciousness. In contrast, connectivity was globally preserved in low-level sensory cortices, (i.e., in auditory and visual networks across sedation stages). This was paired with preserved thalamocortical connectivity in these networks. Rather, waning of consciousness was associated with a loss of cross-modal interactions between visual and auditory networks. CONCLUSIONS: Our results shed light on the functional significance of spontaneous brain activity fluctuations observed in functional magnetic resonance imaging. They suggest that propofol-induced unconsciousness could be linked to a breakdown of cerebral temporal architecture that modifies both within- and between-network connectivity and thus prevents communication between low-level sensory and higher-order frontoparietal cortices, thought to be necessary for perception of external stimuli. They emphasize the importance of thalamocortical connectivity in higher-order cognitive brain networks in the genesis of conscious perception. [less ▲]Detailed reference viewed: 208 (12 ULg)
Side effects of the addition of clonidine 75 microg or sufentanil 5 microg to 0.2% ropivacaine for labour epidural analgesia.
Dewandre, Pierre-Yves ; ; Bonhomme, Vincent et al
in International Journal of Obstetric Anesthesia (2010), 19(2), 149-54
BACKGROUND: Sufentanil 5 microg and clonidine 75 microg produce a similar reduction in minimum local anaesthetic concentration of ropivacaine. The aim of the present study was to compare the side effects ... [more ▼]
BACKGROUND: Sufentanil 5 microg and clonidine 75 microg produce a similar reduction in minimum local anaesthetic concentration of ropivacaine. The aim of the present study was to compare the side effects of two equianalgesic solutions by combining 0.2% ropivacaine with either sufentanil 5 microg or clonidine 75 microg for labour epidural analgesia. METHODS: In a prospective double-blind study, 60 women at 5 cm cervical dilatation were randomly allocated to receive 0.2% ropivacaine with either sufentanil 5 microg or clonidine 75 microg to initiate labour analgesia. The analgesic efficacy and side effects of the two mixtures were compared. RESULTS: Onset, duration and quality of analgesia and subsequent ropivacaine consumption were similar in the two groups. Hypotension was significantly more frequent and severe with clonidine than with sufentanil (systolic blood pressure <100 mmHg: 17/26 vs. 6/24, P <0.05; systolic blood pressure <90 mmHg: 5/26 vs. 0/24, P <0.05) resulting in more frequent ephedrine administration (11/26 vs. 2/24, P <0.05) and larger fluid requirements (1696 +/- 583 mL vs. 1264 +/- 407 mL, P < 0.05). Conversely, pruritus was more frequent with sufentanil than with clonidine (6/26 vs. 1/24, P <0.05). CONCLUSIONS: Hypotension occurs more frequently when clonidine is added to epidural ropivacaine instead of an equianalgesic dose of sufentanil. Therefore, clonidine cannot be recommended for routine administration for labour epidural analgesia. [less ▲]Detailed reference viewed: 74 (0 ULg)
Intracranial subdural hematoma following spinal anesthesia: case report and review of the literature
; ; et al
in Acta Anaesthesiologica Belgica (2010), 61(2), 63-66Detailed reference viewed: 28 (2 ULg)
Effect of an intravenous infusion of lidocaine on cisatracurium-induced neuromuscular block duration: a randomized-controlled trial.
Hans, Grégory ; Defresne, Aline ; et al
in Acta Anaesthesiologica Scandinavica (2010), 54(10), 1192-6
BACKGROUND: Intravenous lidocaine can be used intraoperatively for its analgesic and antihyperalgesic properties but local anaesthetics may also prolong the duration of action of neuromuscular blocking ... [more ▼]
BACKGROUND: Intravenous lidocaine can be used intraoperatively for its analgesic and antihyperalgesic properties but local anaesthetics may also prolong the duration of action of neuromuscular blocking agents. We hypothesized that intravenous lidocaine would prolong the time to recovery of neuromuscular function after cisatracurium. METHODS: Forty-two patients were enrolled in this randomized, double-blind, placebo-controlled study. Before induction, patients were administered either a 1.5 mg/kg bolus of intravenous lidocaine followed by a 2 mg/kg/h infusion or an equal volume of saline. Anaesthesia was induced and maintained using propofol and remifentanil infusions. After loss of consciousness, a 0.15 mg/kg bolus of cisatracurium was administered. No additional cisatracurium injection was allowed. Neuromuscular function was assessed every 20 s using kinemyography. The primary endpoint was the time to spontaneous recovery of a train-of-four (TOF) ratio >/= 0.9. RESULTS: The time to spontaneous recovery of a TOF ratio >/= 0.9 was 94 +/- 15 min in the control group and 98 +/- 16 min in the lidocaine group (P=0.27). CONCLUSIONS: No significant prolongation of spontaneous recovery of a TOF ratio >/= 0.9 after cisatracurium was found in patients receiving intravenous lidocaine. [less ▲]Detailed reference viewed: 69 (3 ULg)
Mécanismes de l'anesthésie générale: apport de l'imagerie fonctionnelle
Boveroux, Pierre ; Bonhomme, Vincent ; Kirsch, Murielle et al
in Revue Médicale de Liège (2009), 64(Synthèse 2009), 36-41Detailed reference viewed: 111 (22 ULg)
Management of the unstable cervical spine: elective versus emergent cases.
Bonhomme, Vincent ; Hans, Pol
in Current Opinion in Anaesthesiology (2009), 22(5), 579-85
PURPOSE OF REVIEW: The present review focuses on similarities and discrepancies in the management of emergent and elective unstable cervical spine (C-spine) patients. RECENT FINDINGS: During mobilization ... [more ▼]
PURPOSE OF REVIEW: The present review focuses on similarities and discrepancies in the management of emergent and elective unstable cervical spine (C-spine) patients. RECENT FINDINGS: During mobilization, lifting is superior to rolling in limiting spine movements. Before prone position surgery, the transfer of the patient on a rotating table is preferable to rolling. In trauma patients, helical computed tomography (CT) with sagittal reconstruction is the first choice for clearing the C-spine. In those patients, airway compromise may be related to hidden cervical edema or hematoma. Several devices can be of help in performing safe tracheal intubation in patients with limited neck movements, but awake fiberoptic intubation remains the safest procedure. The muscle relaxant antagonist sugammadex can improve safety for rapid sequence induction. It can rapidly reverse profound steroid-based neuromuscular blockade and allows avoidance of succinylcholine in this indication. Propofol anesthesia better prevents coughing upon emergence than inhaled anesthesia. Neuroprotection in cord-damaged patients is disappointing, and the controversy on the efficacy of high-dose methylprednisolone is not closed. Nevertheless, maintenance of homeostasis remains the cornerstone of neuroprotection. SUMMARY: Subtle details differentiate the management of emergent and elective unstable C-spine patients. In both situations, the presence or the absence of a neurological insult governs the therapeutic strategy. [less ▲]Detailed reference viewed: 25 (0 ULg)
Perioperative management of a child with von Willebrand disease undergoing surgical repair of craniosynostosis: looking at unusual targets.
Maquoi, Isabelle ; Bonhomme, Vincent ; et al
in Anesthesia and Analgesia (2009), 109(3), 720-4
We report the successful management of a craniosynostosis repair in a child with severe Type I von Willebrand disease diagnosed during the preoperative assessment and treated by coagulation factor VIII ... [more ▼]
We report the successful management of a craniosynostosis repair in a child with severe Type I von Willebrand disease diagnosed during the preoperative assessment and treated by coagulation factor VIII and ristocetin cofactor. Collaboration among the anesthesiologist, the neurosurgeon, the clinical pathologist, and the pediatric hematologist is important for successful management. [less ▲]Detailed reference viewed: 66 (18 ULg)
Acid-base status and hemodynamic stability during propofol and sevoflurane-based anesthesia in patients undergoing uncomplicated intracranial surgery.
Bonhomme, Vincent ; Demoitie, Jeannick ; Schaub, Isabelle et al
in Journal of Neurosurgical Anesthesiology (2009), 21(2), 112-9
Propofol anesthesia may induce metabolic disturbances and sevoflurane anesthesia arterial hypotension. This study compares both techniques regarding acid-base and hemodynamic status during intracranial ... [more ▼]
Propofol anesthesia may induce metabolic disturbances and sevoflurane anesthesia arterial hypotension. This study compares both techniques regarding acid-base and hemodynamic status during intracranial surgery. Sixty-one patients were randomized into 2 groups according to anesthesia maintenance, a propofol group (n=30), and a sevoflurane group (n=31). The anesthesia protocol including rocuronium and remifentanil infusion was otherwise similar in both groups. Arterial blood samples were drawn every 2 hours during the procedure and upon arrival in the intensive care unit to assess acid-base status. The number of hypotensive and hypertensive events served to assess hemodynamic stability. Metabolic acidosis was more frequent during propofol than sevoflurane anesthesia (7 out of 29 and 1 out of 31, P=0.02). Its severity was linearly correlated with lactate concentration (R=0.32), total dose of propofol (R=0.2), and length of procedure (R=0.28). Hyperlactacidemia was also observed during sevoflurane anesthesia, but without acidosis. Hypertension occurred more frequently during propofol than sevoflurane anesthesia (13 out of 30 vs. 1 out of 31, P<0.001), particularly in patients with a past medical history of hypertension. Higher remifentanil infusion rates reduced the risk of hypertension. Conversely, sevoflurane anesthesia favored arterial hypotension (22 out of 31 vs. 12 out of 30, P=0.015). Preoperative morning administration of antihypertensive medications to patients with a history of arterial hypertension was associated with a low probability of hypertensive events, at the cost of more frequent hypotension. In conclusion, propofol anesthesia for intracranial surgery is more frequently associated with lactic acidosis and hypertension; sevoflurane anesthesia may favor arterial hypotension. [less ▲]Detailed reference viewed: 42 (0 ULg)
Bonhomme, Vincent ; Franssen, Colette ; Hans, Pol
in European Journal of Anaesthesiology (2009), 26(11), 906-912
Awake craniotomy has become an increasingly frequent procedure. In this paper, the principles of its anaesthetic management are reviewed. The means allowing achievement of anaesthetic objectives are ... [more ▼]
Awake craniotomy has become an increasingly frequent procedure. In this paper, the principles of its anaesthetic management are reviewed. The means allowing achievement of anaesthetic objectives are described, with emphasis on points that determine success of the procedure. A careful and adequate selection and preparation of patients are mandatory, and the intervening team must be a skilled team. Choosing an awake technique or general anaesthesia depends on several factors, including the risk of obstructive apnoea, seizures, nausea and vomiting, patient's ability to cooperate, and localization of lesions. The main challenge of intraoperative anaesthetic management relies on the ability of rapidly adjusting the level of sedation and analgesia according to the sequence of surgical events, while ensuring haemodynamic stability, adequate ventilation, and minimal interference with eventual eletrophysiological recordings. Throughout the procedure, complications must be anticipated and managed according to predefined guidelines. More prospective randomized clinical trials are still needed to improve safety and efficacy of awake craniotomies, as well as to validate this technique in comparison with more conventional anaesthetic management. [less ▲]Detailed reference viewed: 83 (1 ULg)
Bispectral index correlates with regional cerebral blood flow during sleep in distinct cortical and subcortical structures in humans.
Noirhomme, Quentin ; Boly, Mélanie ; Bonhomme, Vincent et al
in Archives Italiennes de Biologie (2009), 147(1-2), 51-7
The relationship between the Bispectral Index (BIS), an EEG-based monitor of anesthesia, and brain activity is still unclear. This study aimed at investigating the relationship between changes in BIS ... [more ▼]
The relationship between the Bispectral Index (BIS), an EEG-based monitor of anesthesia, and brain activity is still unclear. This study aimed at investigating the relationship between changes in BIS values during natural sleep and regional cerebral blood flow (rCBF) variations, as measured by Positron Emission Tomography (PET). Data were obtained from six young, healthy, right-handed, male volunteers (20-30 years old) using the H2(15)O infusion method. PET scans were performed both during waking and various stages of sleep. BIS values were monitored continuously and recorded during each PET scan. Positive correlations were detected between BIS and rCBF values in dorsolateral prefontal, parietal, anterior and posterior cingulate, precuneal, mesiofrontal, mesiotemporal and insular cortices. These areas belong to a frontoparietal network known to be related to awareness of self conscious sensory perception, attention and memory. BIS values also positively correlated with activity in brainstem and thalami, both structures known to be involved in arousal and wakefulness. These results show that BIS changes associated with physiological sleep depth co-vary with the activity of specific cortical and subcortical areas. The latter are known to modulate arousal, which in turn allows sustained thalamo-cortical enhancement of activity in a specific frontoparietal network known to be related to the content of consciousness. Thus, although mainly derived from frontal EEG, BIS could represent a wider index of cerebral activity. [less ▲]Detailed reference viewed: 62 (7 ULg)
Dose response curve of intravenous lidocaine on the depth of propofol - remifentanil anesthesia assessed byt the bispectral index (BIS) and A-line ARX index (AAI)
; Hans, Grégory ; Lauwick, Séverine et al
in Acta Anaesthesiologica Belgica (2008, June 14), 59(3), 205Detailed reference viewed: 22 (1 ULg)
The Effect of Clonidine Infusion on Distribution of Regional Cerebral Blood Flow in Volunteers
Bonhomme, Vincent ; Maquet, Pierre ; Phillips, Christophe et al
in Anesthesia and Analgesia (2008), 106(3), 899-909
BACKGROUND: Through their action on the locus coeruleus, alpha2-adrenoceptor agonists induce rapidly reversible sedation while partially preserving cognitive brain functions. Our goal in this ... [more ▼]
BACKGROUND: Through their action on the locus coeruleus, alpha2-adrenoceptor agonists induce rapidly reversible sedation while partially preserving cognitive brain functions. Our goal in this observational study was to map brain regions whose activity is modified by clonidine infusion so as to better understand its loci of action, especially in relation to sedation. METHODS: Six ASA I-II right-handed volunteers were recruited. Electroencephalogram (EEG) was monitored continuously. After a baseline H2(15)O activation scan, clonidine infusion was started at a rate ranging from 6 to 10 microg x kg(-1) x h(-1). A sequence of 11 similar scans was then performed at 8 min intervals. Plasma clonidine concentration was measured. Using statistical parametric mapping, we sought linear correlations between normalized regional cerebral blood flow (rCBF), an indicator of regional brain activity, and plasma clonidine concentration or spindle EEG activity. RESULTS: Clonidine induced clinical sedation and EEG patterns (spindles) comparable to early stage nonrapid eye movement sleep. A significant negative linear correlation between clonidine concentration and rCBF or spindle activity was observed in the thalamus, prefrontal, orbital and parietal association cortex, posterior cingulate cortex, and precuneus. CONCLUSIONS: The EEG patterns and decreases in rCBF of specific brain regions observed during clonidine-induced sedation are similar to those of early stage nonrapid eye movement sleep. Patterns of deactivated brain regions are also comparable to those observed during general anesthesia or vegetative state, reinforcing the hypothesis that alterations in the activity of a common network occur during these modified conscious states. [less ▲]Detailed reference viewed: 112 (14 ULg)
Delta down compared with delta pulse as an indicator of volaemia during intracranial surgery
; Bonhomme, Vincent ; Hans, Pol
in British Journal of Anaesthesia (2008), 100(2), 245-250Detailed reference viewed: 32 (4 ULg)
Impact of the addition of sufentanil 5ug or clonidine 75ug on the minimum local analgesic concentration of ropivacaine for epidural analgesia in labour: a randomized comparison
Dewandre, Pierre-Yves ; Kirsch, Murielle ; Bonhomme, Vincent et al
in International Journal of Obstetric Anesthesia (2008), 17Detailed reference viewed: 21 (4 ULg)