Is propofol neurotoxic to the developing brain?
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Anesthetics, Intravenous↗
Biomedical subjects
Hossam El-Beheiry
Publications and source records attributed to Hossam El-Beheiry.
General anesthetics attenuate gap junction coupling in P19 cell line.
Gap junction communication is widespread throughout the mammalian nervous system among neurons as well as glia. We addressed the hypothesis that general anesthetics attenuate gap junction mediated coupling in P19 cell line that can differentiate into neuronal-like cells and astrocytes and oligodendrocytes. We characterized the extent of dye coupling over time in the P19 cell line using colocalization of chlormethylbenzamido-1,1 dioctadecyl-3,3,3',3'-tetramethylindocarbocyamine (CM-DiI) and calcein-AM in donor and recipient cells in cocultures. After seeding, the gap junction permeant dye calcein spreads from donor to recipient cells. CM-DiI and calcein fluorescence identified donor and recipient cells, respectively. The extent of intercellular connections was evaluated using cell counting and flow cytometry up to 2 hr after treatment. Clinically relevant concentrations of the intravenous anesthetics propofol (15 microM) and thiopental (10 microM) attenuated gap junction permeability in P19 cell cultures. In contrast, halothane, a volatile anesthetic in a concentration (0.64 mM) relevant to its free aqueous EC50 had no effect on gap junction coupling; however, very high halothane concentrations (2.8 mM) blocked dye transfer by approximately 90%. The results indicate that halothane concentrations pertinent to clinical anesthesia were unable to attenuate gap junction communication in a cell line that can express neuronal and glial gap junction proteins; however, clinically relevant concentrations of propofol and thiopental depressed gap junction coupling.
Anesthetics, General↗
Calcium chelation improves spatial learning and synaptic plasticity in aged rats.
Impaired regulation of intracellular calcium is thought to adversely affect synaptic plasticity and cognition in the aged brain. Comparing young (2-3 months) and aged (23-26 months) Fisher 344 rats, stratum radiatum-evoked CA1 field EPSPs were smaller and long-term potentiation (LTP) was diminished in aged hippocampal slices. Resting calcium, in presynaptic axonal terminals in the CA1 stratum radiatum area, was elevated in aged slices. Loading the slice with the calcium chelator, BAPTA-AM, depressed LTP in young slices, but enhanced this plasticity in old slices. Forty-five minutes following LTP-inducing high frequency stimulation, resting calcium levels were significantly increased in both young and old presynaptic terminals, and significantly reduced by pretreatment with BAPTA-AM. In vivo, intraperitoneal administration of BAPTA-AM prior to training in the reference memory version of the Morris water maze test, significantly improved the acquisition of spatial learning in aged animals, without a significant effect in young rats. These results support the hypothesis that increasing intracellular neuronal buffering power for calcium in aged rats ameliorates age-related impaired synaptic plasticity and learning.
Aging↗
Venous air embolism during awake craniotomy in a supine patient.
PURPOSE: To report a non-fatal case of intraoperative venous air embolism (VAE) during an awake craniotomy. VAE presented with unusual clinical features. CLINICAL FEATURES: VAE during an awake craniotomy has not been reported frequently. The patient we describe presented with persistent coughing followed by tachypnea, hypoxia and reduction in end-tidal CO(2) during dural opening while undergoing an awake craniotomy in the supine position. Cardiovascular variables were stable during the episode except for transient hypertension. Having ruled out airway obstruction and low cardiac output, we concluded that air embolism was the cause. The patient responded immediately to the standard treatment of air embolism and recovered without any complication. CONCLUSION: This case illustrates a VAE during an awake craniotomy and emphasizes the importance of early diagnosis in the management.
Brain Neoplasms↗
Disclosure of risks associated with regional anesthesia: a survey of academic regional anesthesiologists.
BACKGROUND AND OBJECTIVES: In view of the relatively few large studies available to estimate the rates of complications following regional anesthesia, we aimed to identify and quantify the risks that academic regional anesthesiologists and regional anesthesia fellows disclose to their patients before performing central and peripheral nerve blockade. METHODS: We asked 23 North American regional anesthesia fellowship program directors to distribute a questionnaire to the regional anesthesiologists and regional anesthesia fellows at their institutions. The questionnaire was designed to capture the risks and corresponding incidences that are routinely disclosed to patients before performing the most common central and peripheral nerve block techniques. RESULTS: The total number of respondents was 79 from 12 different institutions. Fifty-eight (74%) respondents disclose risks of regional anesthesia in order to allow their patients to make an informed choice, whereas 20 (26%) disclose risks for medicolegal reasons. For central neural blockade, the most commonly disclosed risks are headache, local pain/discomfort, and infection. For peripheral nerve blockade, the most commonly disclosed risks are transient neuropathy, local pain/discomfort, and infection. For both central and peripheral nerve blockade, the risks most commonly disclosed are also those with the highest-reported incidences. CONCLUSIONS: The risks of regional anesthesia most commonly disclosed to patients by academic regional anesthesiologists and regional anesthesia fellows are benign in nature and occur frequently. Severe complications of regional anesthesia are far less commonly disclosed. The incidences of severe complications disclosed by academic regional anesthesiologists and their fellows can be inconsistent with those cited in the contemporary literature.
Anesthesia, Conduction↗