Electroencephalography (EEG) records brain electrical activity at the scalp level. As a functiona... more Electroencephalography (EEG) records brain electrical activity at the scalp level. As a functional and non invasive witness of brain activity, EEG has long raised the interest of researchers and practitioners, notably in the domain of anesthesia. Thanks to technical advances, this complex signal can now be dissected, and a huge amount of information can be extracted from it. This information gives the opportunity to quantify theeffects of general anesthesia on the brain, and provides a better understanding of the underlying mechanisms.
We report a case of intracranial subdural hematoma following spinal anesthesia in a 28-year-old w... more We report a case of intracranial subdural hematoma following spinal anesthesia in a 28-year-old woman. Subdural hematoma is a very rare, but life-threatening complication. When a patient complains of persistent post spinal headache, one should consider the possibility of subdural hematoma and carry out a careful examination, including MRI or CT scan.
Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation... more Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation by neuronal cells. We demonstrate that medium conditioned by 7‐day‐old rat cerebellar granule neurons or by 16‐day‐old rat embryo hippocampal neurons strongly inhibits the proliferation of cultured astroglial cells. Two neuronal cell lines, the PC12 rat pheochromocytoma and the neuro 2A (N2A) murine neuroblastoma also release such an activity. This release in N2A‐conditioned medium (CM) occurs when the cells are at high density and show a low proliferation rate. This activity is present in media conditioned by neuronal cells, but not in media conditioned by normal astrocytes, by two glioma cell lines, or by one fibroblastic cell line. This proliferation inhibitor addresses normal astrocytes: the proliferation of two glioma cell lines, of a fibroblastic cell line, and of the two neuronal cell lines (PC12, N2A) is not inhibited by N2A CM. Moreover, this activity is directed against type 1...
Obstructive Sleep Apnea (OSA) increases the perioperative risk of complications. Chronic use of C... more Obstructive Sleep Apnea (OSA) increases the perioperative risk of complications. Chronic use of Continuous Positive Airway Pressure (CPAP) by patients decreases the importance of comorbidities caused by the OSA. However, many patients do not adhere to the treatment. Given the postoperative complications, it is important for the anesthesiologist to identify non--adherent patients. This prospective study was designed to identify factors that would predict patient adherence. Ninety patients who were treated by CPAP for more than one year were recruited. Among them, and based on objective criteria such as length of use of CPAP during the night, 75 were considered as being adherent to CPAP, while the other 15 were not. Sixty--two potential causes of non--adherence were investigated (some have not been tested before), and further divided into five categories. Those categories included cultural, intellectual, or economic factors, OSA comorbidities, patient belief about health, ENT--related...
International journal of obstetric anesthesia, 2008
Addition of lipophilic opioids or alpha2-agonists to local anaesthetic solutions reduces local an... more Addition of lipophilic opioids or alpha2-agonists to local anaesthetic solutions reduces local anaesthetic requirements and side effects. While the efficacy and side effects of these adjuvants are dose-related, information about their relative analgesic potencies is lacking, making it difficult to draw meaningful clinical conclusions. The aim of the present study was to assess the relative sparing of ropivacaine by clinically relevant doses of sufentanil and clonidine using the minimum local analgesic concentration (MLAC) model. In this prospective, double-blind study, the sparing effect of sufentanil 5 microg and clonidine 75 microg on the MLAC of ropivacaine administered for labour epidural analgesia was compared in 78 women at <5 cm cervical dilatation. Women were randomly allocated to one of three groups: plain ropivacaine, ropivacaine with sufentanil 5 microg and ropivacaine with clonidine 75 microg. The MLAC of plain ropivacaine was 0.099% wt/vol (95%CI: 0.090 to 0.109) and...
This review aims at defining the link between physiological sleep and general anesthesia. Despite... more This review aims at defining the link between physiological sleep and general anesthesia. Despite common behavioral and electrophysiological characteristics between both states, current literature suggests that the transition process between waking and sleep or anesthesia-induced alteration of consciousness is not driven by the same sequence of events. On the one hand, sleep originates in sub-cortical structures with subsequent repercussions on thalamo-cortical interactions and cortical activity. On the other hand, anesthesia seems to primarily affect the cortex with subsequent repercussions on the activity of sub-cortical networks. This discrepancy has yet to be confirmed by further functional brain imaging and electrophysiological experiments. The relationship between the observed functional modifications of brain activity during anesthesia and the known biochemical targets of hypnotic anesthetic agents also remains to be determined.
The mechanisms underlying anesthesia-induced loss of consciousness remain a matter of debate. Rec... more The mechanisms underlying anesthesia-induced loss of consciousness remain a matter of debate. Recent electrophysiological reports suggest that while initial propofol infusion provokes an increase in fast rhythms (from beta to gamma range), slow activity (from delta to alpha range) rises selectively during loss of consciousness. Dynamic causal modeling was used to investigate the neural mechanisms mediating these changes in spectral power in humans. We analyzed source-reconstructed data from frontal and parietal cortices during normal wakefulness, propofol-induced mild sedation, and loss of consciousness. Bayesian model selection revealed that the best model for explaining spectral changes across the three states involved changes in corticothalamic interactions. Compared with wakefulness, mild sedation was accounted for by an increase in thalamic excitability, which did not further increase during loss of consciousness. In contrast, loss of consciousness per se was accompanied by a d...
Electroencephalography (EEG) records brain electrical activity at the scalp level. As a functiona... more Electroencephalography (EEG) records brain electrical activity at the scalp level. As a functional and non invasive witness of brain activity, EEG has long raised the interest of researchers and practitioners, notably in the domain of anesthesia. Thanks to technical advances, this complex signal can now be dissected, and a huge amount of information can be extracted from it. This information gives the opportunity to quantify theeffects of general anesthesia on the brain, and provides a better understanding of the underlying mechanisms.
We report a case of intracranial subdural hematoma following spinal anesthesia in a 28-year-old w... more We report a case of intracranial subdural hematoma following spinal anesthesia in a 28-year-old woman. Subdural hematoma is a very rare, but life-threatening complication. When a patient complains of persistent post spinal headache, one should consider the possibility of subdural hematoma and carry out a careful examination, including MRI or CT scan.
Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation... more Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation by neuronal cells. We demonstrate that medium conditioned by 7‐day‐old rat cerebellar granule neurons or by 16‐day‐old rat embryo hippocampal neurons strongly inhibits the proliferation of cultured astroglial cells. Two neuronal cell lines, the PC12 rat pheochromocytoma and the neuro 2A (N2A) murine neuroblastoma also release such an activity. This release in N2A‐conditioned medium (CM) occurs when the cells are at high density and show a low proliferation rate. This activity is present in media conditioned by neuronal cells, but not in media conditioned by normal astrocytes, by two glioma cell lines, or by one fibroblastic cell line. This proliferation inhibitor addresses normal astrocytes: the proliferation of two glioma cell lines, of a fibroblastic cell line, and of the two neuronal cell lines (PC12, N2A) is not inhibited by N2A CM. Moreover, this activity is directed against type 1...
Obstructive Sleep Apnea (OSA) increases the perioperative risk of complications. Chronic use of C... more Obstructive Sleep Apnea (OSA) increases the perioperative risk of complications. Chronic use of Continuous Positive Airway Pressure (CPAP) by patients decreases the importance of comorbidities caused by the OSA. However, many patients do not adhere to the treatment. Given the postoperative complications, it is important for the anesthesiologist to identify non--adherent patients. This prospective study was designed to identify factors that would predict patient adherence. Ninety patients who were treated by CPAP for more than one year were recruited. Among them, and based on objective criteria such as length of use of CPAP during the night, 75 were considered as being adherent to CPAP, while the other 15 were not. Sixty--two potential causes of non--adherence were investigated (some have not been tested before), and further divided into five categories. Those categories included cultural, intellectual, or economic factors, OSA comorbidities, patient belief about health, ENT--related...
International journal of obstetric anesthesia, 2008
Addition of lipophilic opioids or alpha2-agonists to local anaesthetic solutions reduces local an... more Addition of lipophilic opioids or alpha2-agonists to local anaesthetic solutions reduces local anaesthetic requirements and side effects. While the efficacy and side effects of these adjuvants are dose-related, information about their relative analgesic potencies is lacking, making it difficult to draw meaningful clinical conclusions. The aim of the present study was to assess the relative sparing of ropivacaine by clinically relevant doses of sufentanil and clonidine using the minimum local analgesic concentration (MLAC) model. In this prospective, double-blind study, the sparing effect of sufentanil 5 microg and clonidine 75 microg on the MLAC of ropivacaine administered for labour epidural analgesia was compared in 78 women at <5 cm cervical dilatation. Women were randomly allocated to one of three groups: plain ropivacaine, ropivacaine with sufentanil 5 microg and ropivacaine with clonidine 75 microg. The MLAC of plain ropivacaine was 0.099% wt/vol (95%CI: 0.090 to 0.109) and...
This review aims at defining the link between physiological sleep and general anesthesia. Despite... more This review aims at defining the link between physiological sleep and general anesthesia. Despite common behavioral and electrophysiological characteristics between both states, current literature suggests that the transition process between waking and sleep or anesthesia-induced alteration of consciousness is not driven by the same sequence of events. On the one hand, sleep originates in sub-cortical structures with subsequent repercussions on thalamo-cortical interactions and cortical activity. On the other hand, anesthesia seems to primarily affect the cortex with subsequent repercussions on the activity of sub-cortical networks. This discrepancy has yet to be confirmed by further functional brain imaging and electrophysiological experiments. The relationship between the observed functional modifications of brain activity during anesthesia and the known biochemical targets of hypnotic anesthetic agents also remains to be determined.
The mechanisms underlying anesthesia-induced loss of consciousness remain a matter of debate. Rec... more The mechanisms underlying anesthesia-induced loss of consciousness remain a matter of debate. Recent electrophysiological reports suggest that while initial propofol infusion provokes an increase in fast rhythms (from beta to gamma range), slow activity (from delta to alpha range) rises selectively during loss of consciousness. Dynamic causal modeling was used to investigate the neural mechanisms mediating these changes in spectral power in humans. We analyzed source-reconstructed data from frontal and parietal cortices during normal wakefulness, propofol-induced mild sedation, and loss of consciousness. Bayesian model selection revealed that the best model for explaining spectral changes across the three states involved changes in corticothalamic interactions. Compared with wakefulness, mild sedation was accounted for by an increase in thalamic excitability, which did not further increase during loss of consciousness. In contrast, loss of consciousness per se was accompanied by a d...
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Papers by V. Bonhomme