Kappa opioids inhibit physiologically identified medullary pain modulating neurons and reduce morphine antinociception.

Microinjection of kappa opioid receptor (KOR) agonists into the rostral ventromedial medulla (RVM) attenuates mu-opioid receptor mediated antinociception and stress-induced analgesia, yet is also reported to have an analgesic effect. To determine how KOR agonists produce both antinociceptive and antianalgesic actions within the RVM, the KOR agonist U69593 was microinjected directly into the RVM while concurrently monitoring tail flick latencies and RVM neuronal activity. Among RVM neurons recorded in vivo, two types show robust changes in activity just prior to the nocifensive tail flick reflex: ON cells burst just prior to a tail flick and their activity is pronociceptive, whereas OFF cells pause just prior to the tail flick and their activity is antinociceptive. Although RVM microinjection of U69593 did not affect tail flick latencies on its own, it did attenuate the on cell burst, an effect blocked by co-injection of the KOR antagonist, nor-binaltorphimine (nor-BNI). Furthermore, U69593 inhibited ongoing activity in subsets of OFF cells (4/11) and NEUTRAL cells (3/9). Microinjection of U69593 into the RVM also attenuated morphine antinociception and suppressed the excitation of off cells. Together with previous in vivo and in vitro studies, these results are consistent with the idea that KOR agonists can be either pronociceptive through direct inhibition of OFF cells, or antianalgesic through both postsynaptic inhibition and presynaptic inhibition of glutamate inputs to RVM OFF cells.

[Pseudohypoxemia in a patient with chronic myeloid leukemia and splenomegaly].

A 35-year-old man with chronic myeloid leukemia whose peripheral leukocyte count was 18.6 x 10(4).mm-3 underwent splenectomy. Perioperative arterial blood gas analysis showed lower oxygen saturations than those measured with pulse oximetry. The findings suggested pseudohypoxemia because of marked leukocytosis.

Delta opioid receptor mediated actions in the rostral ventromedial medulla on tail flick latency and nociceptive modulatory neurons.

The rostral ventromedial medulla (RVM) is critical for the modulation of dorsal horn nociceptive transmission. Three classes of RVM neurons (ON, OFF, and NEUTRAL) have been described that have distinct responses to noxious stimuli and mu opioid receptor (MOR) agonists. The present study in barbiturate anesthetized rats investigated the effects of the delta 2 opioid receptor (DOR2) agonist, [D-Ala2]deltorphin II (DELT), microinfused into the RVM on the tail flick reflex and activity of RVM neurons. Tail flick latencies increased dose-dependently after administration of DELT (0.6 nmol and 1.2 nmol). Furthermore, DELT inhibited the tail flick related increase in ON cell activity and shortened the tail flick related pause in OFF cell activity. The activity of NEUTRAL cells was not affected. The antinociceptive effects and corresponding changes in ON and OFF cell activity produced by DELT were antagonized by the DOR2 antagonist, naltriben methanesulfonate, administered at the same site. These DOR2 mediated effects on noxious stimulation-evoked changes in RVM neuronal activity are similar to those reported for MOR agonists and suggest that both DOR2 and MOR produce analgesia through activation of OFF cells.

Disappearance of wheezing during epidural lidocaine anesthesia in a patient with bronchial asthma.

BACKGROUND AND OBJECTIVES: Local anesthetics in blood absorbed from the epidural space attenuate bronchial hyperreactivity to chemical stimuli. However, it is not documented whether local anesthetics at clinically relevant concentrations improve active wheezing in patients with bronchial asthma. CASE REPORT: We managed a 60-year-old man with bronchial asthma and active wheezing under continuous epidural anesthesia using plain lidocaine. The wheezing gradually diminished 20 minutes after the epidural injection of 13 mL 2% lidocaine and completely disappeared over 155 minutes during continuous epidural injection of 2% lidocaine (6 mL/h). The plasma concentrations of lidocaine in arterial blood during the epidural anesthesia ranged from 2.5 to 3.9 microg/mL. Wheezing reappeared 55 minutes after termination of the continuous epidural injection of lidocaine. The plasma concentration of lidocaine at this time was 1.9 microg/mL. CONCLUSIONS: At clinically relevant concentrations, lidocaine in the blood absorbed from the epidural space may improve bronchospasm in patients with bronchial asthma.

Midbrain periaqueductal gray (PAG) inhibits nociceptive inputs to sacral dorsal horn nociceptive neurons through alpha2-adrenergic receptors.

Modulation of sacral spinal dorsal horn neurons by the ventrolateral PAG was studied by extracellular recording combined with microiontophoretic applications of alpha-adrenergic agonists or antagonists. Bicuculline (BIC, 15 ng) microinjected into the ventrolateral PAG produced a consistent inhibition of the responses of nociceptive dorsal horn neurons. After PAG-BIC applications, the total number of spikes per heat stimulation period was significantly decreased to a mean of 37 +/- 19% (n = 8) of the pre-BIC control. Local iontophoresis of the selective alpha2-adrenoceptor antagonists idazoxan or yohimbine but not the selective alpha1 antagonist benoxathian significantly reversed PAG-BIC-evoked inhibition. At low ejection currents, clonidine, an alpha2-adrenoceptor agonist, markedly reduced noxious heat-evoked responses but had no consistent action on the responses to iontophoresed excitatory amino acids [EAA; N-methyl--aspartate (NMDA) or kainic acid]. At ejection currents higher than required to block descending inhibition, idazoxan potentiated responses to both heat and EAA iontophoresis. At higher ejection currents, EAA responses were inhibited by clonidine. This indicates that both presynaptic and postsynaptic alpha2 receptors are capable of inhibiting the recorded neurons. Activation of the alpha1 adrenoceptors by iontophoresis of methoxamine often led to a marked increase in the responses to kainic acid and, to a lesser extent, to NMDA iontophoresis or noxious heat. Together with previously reported work, the current experiments demonstrate that PAG neurons inhibit nociceptive dorsal horn neurons primarily through an indirect alpha2 adrenoceptor mechanism. In this same population of dorsal horn neurons, norepinephrine has a direct alpha1-mediated excitatory effect.

High thoracic epidural block relieves acute herpetic pain involving the trigeminal and cervical regions: comparison with effects of stellate ganglion block.

BACKGROUND AND OBJECTIVES: Stellate ganglion block can promptly relieve acute herpetic pain (AHP) involving the trigeminal and cervical regions. However, repeated blocks are needed to maintain pain relief in most patients with severe AHP. Because continuous epidural block is easily performed using an indwelling catheter, we compared the effect of high thoracic epidural block with that of stellate ganglion block to relieve moderate-to-severe AHP involving these regions. METHODS: Six patients received stellate ganglion blocks and seven patients received high thoracic epidural blocks. Six milliliters 1% of mepivacaine was given to each patient. Acute herpetic pain was evaluated before and up to 60 minutes after the blocks, using a visual analog scale (VAS) of pain. RESULTS: There was no significant difference in VAS pain scores before the blocks between the groups, but there were significant (P < .05) decreases in VAS pain scores for both groups between 10 and 60 minutes after the blocks. There were no significant differences in VAS pain scores between the groups after the blocks. CONCLUSIONS: High thoracic epidural block was as effective as stellate ganglion block in relieving moderate-to-severe AHP involving the trigeminal and cervical regions.

[Pediatric one-lung anesthesia with a Fogarty catheter].

One-lung anesthesia using a Fogarty catheter in pediatric patients is presented. Case 1 is an 8 year old male with coarctation of the aorta scheduled for coarctectomy. Case 2 is a 13 year old female with metastatic lung tumor scheduled for partial resection of the left upper lobe under thoracoscopic surgery. One-lung anesthesia was successfully established with a Fogarty catheter in both patients and no hypoxic episode was encountered during the one-lung anesthesia. Postoperatively, there was no evidence of atelectasis of the lung or barotrauma to the trachea or bronchus. Thus, the Fogarty catheter appears useful for pediatric one-lung anesthesia, especially when the double lumen endobronchial tubes or endobronchial blockers of smaller sizes are not available.

[Anesthesia for a patient with olivopontocerebellar atrophy].

Olivopontocerebellar atrophy (OPCA) is one of the spinocerebellar degenerative diseases. Reports of patients complicated with OPCA are scarce in anesthetic literature. We managed a 79-year-old woman with sialolithiasis of the left submandibular gland complicated with OPCA. She underwent a removal of the gland under general anesthesia using oxygen, nitrous oxide, and isoflurane (0.6-2.0%). Blood pressure decreased transiently after induction of anesthesia, but, no vasopressors were needed to maintain the blood pressure during the surgery. There were no untoward cardio-respiratory events after the surgery. Perioperative anesthetic management of patients with OPCA is also discussed.

[Evaluation of agar media for growth of Campylobacter pylori].

The supporting ability for the growth of Campylobacter pylori was tested on various agar plates. C. pylori grew on media supplemented with blood, serum or egg-yolk, and it showed good growth on Mueller Hinton agar with horse blood, and on brain-heart infusion agar with yeast extract and horse blood. The organism grew moderately on Mueller Hinton agar, but could not grow on the other unsupplemented media. Mueller Hinton medium may be of use as a proper base of blood agar for growth of C. pylori. Egg-yolk may be substituted as a low-priced enrichment material for blood.