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ABSTRACT: We report 2 patients for whom anesthetic management using aortic occlusion balloon catheter (AOBC) was performed thrice. A 14-year-old boy and a 43-year-old man with sacral giant cell tumor underwent tumor resection. In both patients, transcatheter arterial embolization (TAE) was performed several times before the operation. Before the surgery, an AOBC was inserted via the right femoral artery. For tumor resection, the AOBC was inflated, and a slight decrease in hemorrhage was observed. The occlusion was maintained for 40-55 min, with a loss of 1,400-3,700 ml of blood. In case 1, moderate bleeding from the epidural venous plexus was observed. In case 2, packed red blood cell transfusion was needed, and the patient returned to surgery for hemostasis. Because the AOBC could not decrease the severity of venous hemorrhage, we expected increased hemorrhage with an increase in the extent of surgery. In addition, preoperative multiple TAE might lead to the development of collateral circulation around the sacrum and augment the amount of blood loss in that region. Although the AOBC could reduce intraoperative hemorrhage, uncontrollable bleeding may occur if the sacral giant cell tumor shows extensive dissemination.
Masui. The Japanese journal of anesthesiology 06/2012; 61(6):610-3.
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ABSTRACT: Opioids inhibit excitatory neurotransmission and produce antinociception through μ opioid receptors (MORs). Although MORs are expressed in the spinal ventral horn, their functions and effects are largely unknown. Therefore, we examined the neuromodulatory effects of μ opioids in spinal lamina IX neurons at the cellular level.
The effects of the selective μ agonist [D-Ala(2),-N-Me-Phe(4), Gly(5)-ol]enkephalin (DAMGO) on synaptic transmission were examined in spinal lamina IX neurons of neonatal rats using the whole-cell patch-clamp technique.
DAMGO produced outward currents in 56% of the lamina IX neurons recorded, with a 50% effective concentration of 0.1 μM. Analysis of the current-voltage relationship revealed a reversal potential of approximately -86 mV. These currents were not blocked by tetrodotoxin but were inhibited by Ba(2+) or a selective μ antagonist. Moreover, the currents were suppressed by the addition of Cs(+) and tetraethylammonium or guanosine 5'-[β-thio]diphosphate trilithium salt to the pipette solution. In addition, DAMGO decreased the frequency of spontaneous excitatory and inhibitory postsynaptic currents, and these effects were unaltered by treatment with tetrodotoxin.
Our results suggest that DAMGO hyperpolarizes spinal lamina IX neurons by G protein-mediated activation of K(+) channels after activation of MORs. Furthermore, activation of MORs on presynaptic terminals reduces both excitatory and inhibitory transmitter release. Although traditionally opioids are not thought to affect motor function, the present study documents neuromodulatory effects of μ opioids in spinal lamina IX neurons, suggesting that MORs can influence motor activity.
Anesthesia and analgesia 05/2012; 115(3):703-12. · 3.08 Impact Factor
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ABSTRACT: The minimum alveolar concentration is determined in the spinal cord rather than in the brain. Xenon inhibits glutamatergic excitatory synaptic transmission in the dorsal horn neurons. However, its actions in the ventral horn neurons have not been investigated.
The effects of 50 or 75% xenon on excitatory and inhibitory synaptic transmission were examined in the spinal lamina IX neurons of neonatal rats by using a whole cell patch clamp technique.
Fifty percent xenon inhibited the α-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid-induced currents (amplitudes = 72 ± 9% and integrated area = 73 ± 13% of the control values), and α-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid receptor-mediated electrically evoked excitatory postsynaptic currents (amplitudes = 69 ± 13% of the control values). Seventy-five percent xenon similarly inhibited α-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid-induced currents. However, xenon had no effect on the N-methyl-D-aspartate-induced currents or N-methyl-D-aspartate receptor-mediated electrically evoked excitatory postsynaptic currents. Xenon decreased the amplitude, but not the frequency, of miniature excitatory postsynaptic currents. There were no discernible effects on the currents induced by γ-aminobutyric acid or glycine or on miniature inhibitory postsynaptic currents.
Xenon inhibits α-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid receptor-mediated glutamatergic excitatory transmission in the spinal lamina IX neurons via a postsynaptic mechanism. In contrast, there are no substantial effects on N-methyl-D-aspartate receptor-mediated or inhibitory synaptic transmission. The suppressive effects on excitatory synaptic transmission in the ventral horn neurons partly account for the mechanism behind xenon's ability to produce immobility in response to noxious stimuli and to determine the minimum alveolar concentration.
Anesthesiology 03/2012; 116(5):1025-34. · 5.36 Impact Factor
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Anesthesiology 11/2011; 116(2):485-7. · 5.36 Impact Factor
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ABSTRACT: The essential elements of anesthesia are : hypnosis, amnesia, analgesia, immobility, and inhibition of untoward reflexes. The spinal cord is responsible for the latter three. Suppression of excitatory transmission and stimulation of inhibitory transmission are the anesthetic mechanisms in the spinal cord. Each anesthetic, however, has a unique effect on the transmission systems in the spinal cord. Some exclusively suppress excitatory transmission or stimulate inhibitory transmission, and others have a dual effect. The minimum alveolar/anesthetic concentration (MAC) is spinally mediated. Furthermore neurons in the ventral horn of spinal cord seem to be more depressed by anesthetics than neurons in the dorsal horn of the spinal cord. The ventral spinal cord also has relation to spinal cord ischemia. Investigation of the neuroprotective effect against spinal ischemia as well as the anesthetic effect in the ventral spinal cord is a very important subject of research.
Masui. The Japanese journal of anesthesiology 05/2011; 60(5):582-9.
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ABSTRACT: To clarify the vulnerability of spinal motoneurons to excitotoxicity, we analyzed the agonal current induced by experimental ischemia in ventral lamina IX neurons of spinal cord slices from neonatal rats by using whole-cell patch-clamp. Ischemia was simulated in vitro by oxygen/glucose deprivation. Superfusion with ischemia-simulating medium elicited an agonal inward current, which was initially slow and then became rapid. We compared 8-, 9-, 10-, 11-, and 12-day postnatal rats and found age-dependent shortening of the latency of the rapid inward current. Furthermore, the membrane capacitance (Cm) and resting membrane potential (RMP) of the lamina IX neurons demonstrated significant negative correlations with the latency of the rapid inward current. Logistic regression analysis showed that postnatal age, Cm, and RMP were independent contributing factors to ischemic vulnerability. These results suggest that not only cell volume and ionic balance but also early postnatal maturation of the intracellular environment is vital for developing vulnerability to excitotoxicity.
Neuroscience Letters 03/2011; 494(2):161-4. · 2.11 Impact Factor
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ABSTRACT: We report successful epidural anesthetic management in a patient with severely impaired respiratory function. A 47-year-old woman (39 kg, 158 cm) was scheduled for right thoracoplasty. She had undergone fenestration surgery for empyema three months previously and required supplemental oxygen. Her vital capacity was 700 ml and forced expiratory volume in one second was 650 ml, indicating a severe restrictive pulmonary disorder. Hence, in order to avoid general anesthesia with tracheal intubation, we opted for epidural anesthesia. An epidural catheter was inserted in the T6-7 interspace and a bolus of 4.5 ml each of 1% mepivacaine and 1% ropivacaine was injected through the epidural catheter after a test dose. Ten minutes after the injection, the patient complained of difficulty in breathing and her oxygen saturation fell from 96% to 93%. We applied noninvasive positive pressure ventilation (NPPV) via a nasal mask to the patient, with the ventilator set at spontaneous/timed mode with inspiratory/expiratory positive airway pressure of 14/5 cmH2O. With this therapy, the patient's respiratory symptoms subsided rapidly and we could maintain adequate oxygenation and ventilation throughout the operation. We believe that epidural anesthesia with NPPV is a useful option for patients with compromised respiratory function.
Masui. The Japanese journal of anesthesiology 04/2010; 59(4):467-9.
