The effects of 30% and 60% xenon inhalation on pial vessel diameter and intracranial pressure in rabbits

Xenon may increase cerebral blood flow and intracranial pressure (ICP). To evaluate the effects of xenon on brain circulation, we measured pial vessel diameter changes, CO(2) reactivity, and ICP during xenon inhalation in rabbits. Minimum alveolar anesthetic concentration (MAC) for xenon was established in rabbits (n = 6). By using a cranial window model, pial vessel diameters were measured at 30% and 60% xenon inhalation and in time control groups (n = 15). ICP, mean arterial blood pressure, and heart rate were recorded during 30% and 60% xenon inhalation (n = 5). Pial vessel diameters were measured during hypocapnia and hypercapnia conditions in 60% Xenon and Control groups (n = 14). MAC for xenon was 85%. Xenon (0.35 and 0.7 MAC) dilated the arterioles (10% and 18%, respectively) and venules (2% and 4%, respectively) (P < 0.05). Dilation of arterioles was more prominent than that of venules. ICP, mean arterial blood pressure, and heart rate did not change during xenon inhalation. No difference in CO(2) reactivity was observed between Xenon and Control groups (P = 0.79). Sixty percent xenon (0.7 MAC) dilated brain vessels, but venule changes were small. Xenon did not increase ICP and preserved CO(2) reactivity of the brain vessels.

IMPLICATIONS

Xenon might increase cerebral blood flow; however, 0.7 minimum alveolar anesthetic concentration xenon preserved both low intracranial pressure and CO(2) reactivity of the cerebral vessels in the normal rabbit.

[Dose-response study of preincisional buprenorphine on emergence time and postoperative analgesic requirement in patients anesthetized with sevoflurane]

The effect of intravenous buprenorphine on emergence time from sevoflurane anesthesia and postoperative analgesic requirement was evaluated after otolaryngeal surgeries. Forty-five patients were randomly assigned to one of three treatment groups (n = 15 each): Control-group received saline as a control; 2 micrograms-group received buprenorphine 2 micrograms.kg-1; and 4 micrograms-group received buprenorphine 4 micrograms.kg-1, respectively. Study drug was administered intravenously at the induction of general anesthesia. Anesthesia was maintained with sevoflurane (1.5%) and nitrous oxide (66%) in oxygen. The pain score, postoperative analgesic requirement, and incidence of nausea and/or vomiting were examined. The emergence times were 16.4 +/- 3.5, 14.7 +/- 5.2, and 17.8 +/- 7.7 min [mean +/- SD], in the control-group, the 2 micrograms-group, and the 4 micrograms-group, respectively. There were no differences among the groups in term of the end-tidal sevoflurane concentration immediately before tracheal extubation. In the control-group, the 2 micrograms-group, and the 4 micrograms-group, 10, 1, and 3 patients, requested additional analgesics during the first 24 hours after surgery, respectively (control-group vs. 2 micrograms-group and 4 micrograms-group, P < 0.05). Nausea and vomiting occurred more frequently in the 2 micrograms-group and the 4 micrograms-group. We conclude that buprenorphine (2 or 4 micrograms.kg-1) reduced analgesic requirement during the first 24 hours after surgery without delaying emergence from sevoflurane anesthesia.

[Anesthetic management for left ventricular assist device implantation in patients waiting for heart transplantation]

We report the anesthetic management of patients with dilated cardiomyopathy who underwent left ventricular assist device implantation (LVAD). Anesthesia was induced and maintained with midazolam and fentanyl. Transesophageal echocardiography (TEE) and a PA catheter were useful for hemodynamic monitoring and management of the patients. Furthermore, TEE is useful for the early detection of inflow of the air which is absorbed by negative pressure derived from high LVAD support pressure. On starting LVAD support, evaluation of right ventricular function and treatment for right ventricular failure were important and necessary for the patients. Added to conventional therapy using catecholamines, inhaled nitric oxide may provide a favorable effect for right ventricular failure.

[Estimation of daily dietary intake of aluminum]

The daily dietary intake of aluminum was estimated through a total diet study from 1996 to 1998. In ten institutes, total diet study samples were prepared and their aluminum concentration was determined. The average daily intake of aluminum was 3.5 mg and the range was 1.8-8.4 mg. The validity of the analytical result was supported by analyses of certified reference materials.

Plasma lidocaine, monoethylglycinexylidide, and glycinexylidide concentrations after epidural administration in geriatric patients

BACKGROUND AND OBJECTIVES

The purpose of this study was to evaluate the effect of age on the pharmacokinetics of lidocaine after epidural administration.

METHODS

Two percent lidocaine with epinephrine (5 microg/mL) was administered in two different age groups: an adult group (age 42 +/- 6 years, n = 10) and an elderly group (age 77 +/- 4 years, n = 10). Concentrations of lidocaine and its active metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), were measured in plasma samples obtained after 15, 30, 45, 60, 90, 120, 150, and 180 minutes of administration using high-performance liquid chromatography with ultraviolet detection.

RESULTS

No significant differences in plasma concentrations of lidocaine and its metabolites were observed between the two groups during the 3 hours of study. However, the elderly group showed significantly longer mean residence times (MRTs) and lower plasma clearance of lidocaine during the period compared with the adult group (P < .05). Plasma concentration ratios of MEGX/lidocaine were significantly lower in the elderly group after 2 hours of lidocaine administration (P < .05).

CONCLUSIONS

The increase in plasma lidocaine concentration after epidural anesthesia in elderly patients was not as high as anticipated. However, the elderly patients showed longer MRTs, lower clearance, and lower ratios of MEGX/lidocaine than did the adult (middle-age) patients.

Modifications of the hemodynamic consequences of theophylline intoxication with landiolol in halothane-anesthetized dogs

PURPOSE

To examine the effect of landiolol (ONO-1101), a new ultra-short acting, highly selective beta1 blocker, on hemodynamic response to acute theophylline intoxication in anesthetized dogs.

METHODS

Thirty-four dogs were studied during halothane anesthesia. Aminophylline (50 mg x kg(-1) over 20 min followed by infusion at 1.75 mg x kg(-1) x hr(-1)) was administered as a model of acute theophylline intoxication. Dogs were randomly enrolled into four landiolol groups (0, 1, 10, 100 microg x kg(-1) x min(-1)) to treat tachyarrhythmias. Hemodynamic variables, heart rate (HR), systemic blood pressure (SBP), pulmonary artery pressure, pulmonary artery occlusion pressure, and cardiac output (CO) were measured along with plasma concentrations of theophylline, epinephrine, and norepinephrine.

RESULTS

After 60 min, plasma concentration of theophylline reached 46.6+/-4.0 (mean +/- SD) microg x ml(-1), HR increased from 129+/-21 to 193+/-27 bpm (P<0.0001) and CO increased from 1.6+/-0.5 l x min(-1) to 2.1+/-0.4 l x min(-1) (P<0.0001), whereas SBP decreased from 139+/-25 to 121+/-25 mm Hg (P<0.0001), with decreasing systemic vascular resistance. After intoxication, plasma epinephrine concentration increased from 125 +/-112 to 325+/-239 pg x ml(-1) (P<0.0001), and norepinephrine concentration from 103+/-61 to 133+/-61 pg x ml(-1) (P<0.0011). Landiolol 10 microg x kg(-1) x min(-1) decreased HR to pre-intoxication level, whereas HR returned to the intoxication baseline by 30 min after cessation of landiolol infusion.

CONCLUSIONS

Landiolol controlled tachyarrhythmias associated with theophylline toxicity. The optimal effective dose of landiolol was 10 microg x kg(-1) x min(-1).

S-Nitroso-N-acetylpenicillamine (SNAP) during hemorrhagic shock improves mortality as a result of recovery from vascular hyporeactivity

Nitric oxide donors are protective against hemorrhagic shock (HS). However, no detailed investigation has been performed. We investigated this mechanism using S-nitroso-N-acetylpenicillamine (SNAP). HS (mean arterial pressure: 40 mm Hg) was induced in 20 dogs. Sixty min after HS, the animals were treated with saline (Cont-Gr: n = 7) or SNAP; 5 microg. kg(-1). 10 min(-1) followed by 5 microg. kg(-1). h(-1) (SNAP-Gr: n = 7). After another 60 min, the shed blood was reinfused. Reactivities to noradrenalin (NA), changes in hemodynamics, the plasma catecholamines, and nitric oxide derivatives were determined. In Cont-Gr, 3 dogs died at 90, 98, and 102 min after HS. In Cont-Gr, % changes of systolic arterial blood pressure to 1 and 2.5 microg/kg of NA after the recovery from HS decreased from 23.7% +/- 4.1% (before HS) to 6.5% +/- 0.6% and from 50.1% +/- 7.7% (before HS) to 14.5% +/- 2.6%, respectively (P < 0. 01). In SNAP-Gr, reactivity to NA was maintained. At 120 min after HS, mean arterial pressure and cardiac output in SNAP-Gr increased but not in Cont-Gr. Plasma catecholamine levels in SNAP-Gr were suppressed compared with those of Cont-Gr. In conclusion, a small dose of SNAP during HS decreased the mortality of the dogs. This might have been caused in part by residual vascular hyporeactivity.

IMPLICATIONS

The administration of a small dose of S-nitroso-N-acetylpenicillamine (a nitric oxide donor), a dose which did not exert a significant vasodilator effect, was administered during hemorrhagic shock in dogs. S-nitroso-N-acetylpenicillamine improved the vascular hyporeactivity to noradrenaline and decreased the mortality rate.

[Epidural anesthesia for cesarean section in a patient with dilated cardiomyopathy (DCM)]

A 23-year-old patient with dilated cardio myopathy (DCM) was scheduled for a cesarean section. We inserted an epidural catheter at the L 2/3 interspace and injected 1.5% lidocaine 6 ml with epinephrine 30 micro g and fentanyl 50 micro g. The analgesic level 15 minutes after injection was achieved up to the eighth thoracic dermatome. Dopamin 5 micro g.kg-1.min-1 was infused simultaneously. Analgesia was sufficient for the surgery, and heart rate and blood pressure were stable throughout the operation. The infant's apgar scores were 9 and 10. Epidural anesthesia is one of the options for cesarean section in pregnant women with DCM.

Plasma concentrations of lidocaine and its principal metabolites during continuous epidural infusion of lidocaine with or without epinephrine

BACKGROUND AND OBJECTIVES

The purpose of this study was to evaluate the effect of epinephrine on the absorption of lidocaine and the accumulation of active metabolites of lidocaine during continuous epidural anesthesia.

METHODS

Lidocaine was administered as an initial bolus of 5 mg/kg of 2% lidocaine solution followed by continuous infusion at 2.5 mg/kg/h. Patients in group I (n = 10) received lidocaine alone and patients in group II (n = 10) received lidocaine + epinephrine (5 pg/mL). Concentrations of lidocaine and its active metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), were measured in plasma samples obtained after 15 minutes, 30 minutes, and 1, 2, and 3 hours of infusion using high-performance liquid chromatography with ultraviolet detection.

RESULTS

Plasma lidocaine concentrations were higher in group I for the first 30 minutes; however, after 1 hour the levels were the same. Plasma MEGX and GX increased continuously in both groups. MEGX levels the were significantly higher in group I, but there was no significant difference in the sum of lidocaine + MEGX after 2 hours. There was no significant difference in GX levels between the two groups.

CONCLUSIONS

With respect to continuous epidural administration, addition of epinephrine to lidocaine solutions is ineffective after 2 hours for reducing the potential for systemic toxicity, because the sum of the plasma concentrations of lidocaine and its principal active metabolite, MEGX, are unaffected.

Effect of plasma alpha1-acid glycoprotein concentration on the accumulation of lidocaine metabolites during continuous epidural anesthesia in infants and children

OBJECTIVE

Alpha1-acid glycoprotein (AAG) is an acute-phase protein that is responsible for binding basic drugs such as lidocaine (LDC). The effect of AAG on the duration of LDC during continuous epidural anesthesia in infants and young children was investigated.

PATIENTS, MATERIALS AND METHODS

Plasma levels of LDC and its active metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), were monitored in 20 infants and children, 5 months to 6 years of age, who received continuous epidural infusion of 2.5 mg kg(-1) LDC hourly during abdominal or thoracic surgeries.

RESULTS

Plasma LDC concentrations were constant after the first hour of injection. In contrast, the concentrations of MEGX and GX increased continuously during epidural infusion in all patients. The plasma AAG concentration correlated significantly (r = 0.814, p<0.001) with the steady-state LDC level. In addition, significant inverse correlation was observed between the plasma AAG concentration and the accumulation rate of MEGX (r = 0.742, p = 0.002). The plasma AAG concentration and the accumulation rate of GX correlated weakly (r = 0.474, p = 0.035). There was no correlation between the age of the patient and the plasma AAG concentrations (r = 0.295, p = 0.206).

CONCLUSION

Our results suggest that the plasma AAG concentration is a valuable index in preventing the toxicity caused by accumulation of MEGX during continuous epidural anesthesia of LDC.

A survey of ochratoxin A and aflatoxins in domestic and imported beers in Japan by immunoaffinity and liquid chromatography

Analyses of ochratoxin A (OTA) and aflatoxins (AFs) in 94 imported beer samples from 31 producing countries and in 22 Japanese beer samples were performed by immunoaffinity column and reversed-phase liquid chromatography (LC) with fluorescence detection. Recoveries of OTA from beer samples spiked at 25 and 250 pg/mL were 86.1 and 88.2%, respectively. Recoveries of AFs were 98.4 and 98.9%, 95.4 and 95.5%, 101.2 and 97.8%, and 98.9 and 96.0%, respectively, from beer samples spiked at 4.1 and 41 pg AF B1, 4.45 and 44.5 pg AF B2, 4.7 and 47 pg AF G1, and 4.65 and 46.5 pg AF G2/mL. Detection limits were 1.0 pg/mL for OTA, 0.5 pg/mL for AFs B1 and B2, and 1.0 pg/mL for AFs G1 and G2. OTA was detected in 86 (91.5%) of 94 imported beer samples at a mean level of 10.1 pg/mL and in 21 (95.5%) of 22 Japanese beer samples at a mean level of 12.5 pg/mL. AF B1 was detected in 11 of 94 imported beer samples at a level of 0.5-83.1 pg/mL and in 2 of 22 Japanese beer samples at 0.5 and 0.8 pg/mL. Except for one beer sample from Peru, the samples contaminated with AFs were also contaminated with OTA. Although OTA was detected in most samples from various countries, AFs were detected in the beer samples from only a limited number of countries where AF contamination might be expected to occur because of their warm climate.

Landiolol decreases a dysrhythmogenic dose of epinephrine in dogs during halothane anesthesia

PURPOSE

To examine the effect of landiolol (ONO-1101), a new ultra-short acting and highly selective beta blocker, on epinephrine-induced ventricular arrhythmias in halothane-anesthetized dogs.

METHODS

We administered five different doses (0, 0.1, 0.5, 1.0, 10 microg x kg(-1) x min(-1)) landiolol and determined the dysrhythmogenic dose of epinephrine (DDE), defined as the smallest dose producing four or more PVCs within 15 sec, at each dose of landiolol and after cessation of infusion.

RESULTS

The control value of DDE during 1.3 MAC halothane anesthesia was 1.26 +/- 0.44 (mean +/- SD) microg x kg(-1) x min(-1) and the corresponding plasma concentration of epinephrine (PCE) was 12.2 +/- 8.3 ng x ml(-1). Concomitant administration of 10 microg x kg(-1) x min(-1) landiolol increased DDE and corresponding PCE (P < 0.05). At 30 min after cessation of landiolol infusion, DDE and corresponding PCE returned to the control values.

CONCLUSIONS

Landiolol, at a dose of 10 microg x kg(-1) x min(-1), has an antiarrhythmic effect on epinephrine-induced ventricular arrhythmias in dogs during anesthesia with halothane.

[Ketamine infusion therapy for refractory neuralgia in spinal disease: report of two cases]

We report two cases of refractory pain in a spinal disease. One case was a 60-year-old male who presented intractable pain in bilateral upper extremities after anterior fusion (C5/6, 6/7) for cervical spondylosis. The other was a 63-year-old female who also had intractable pain in the left anterio-lateral chest wall with no remarkable past history. Both cases were refractory to nonsteroidal anti-inflammatory drugs (NSAIDs) or minor tranquilizer or local anesthesia with bupivacaine. However, their pain was significantly relieved by the intravenous administration of a test dose (5mg) of ketamine which is a noncompetitive blocker of N-methyl-D-aspartate (NMDA) receptors. As for case 1, the effect of the injection of the test dose lasted, so continuing infusion therapy of ketamine was cancelled. In case 2, recurrence of the pain was recognized gradually. She underwent continuing infusion therapy of 2mg/kg of ketamine, and it brought about continued pain relief. We conclude that ketamine infusion therapy should also be considered for therapy of refractory neuralgia in spinal disease.

Nitric oxide in the liver may not be involved in blood redistribution during hemorrhagic shock in the dog

We previously reported that nitric oxide (NO) in the brain cortex increases during hemorrhagic shock (HS) and then recovers to a baseline level by a retransfusion. Accordingly, we suggested that NO may play a role in blood redistribution during HS. To ascertain whether or not NO contributes to blood redistribution, we have investigated the changes in the liver's NO production during HS. Mongrel dogs were used in the study. After each dog was anesthetized with pentobarbital, an NO-selective electrode was placed in its liver, and a probe to measure hepatic blood flow (HF) was placed on the liver's surface. HS was induced until a mean arterial blood pressure of <40 mmHg was reached. In Group I (n=5), HS was maintained for 30 min. In Group II (n=7), shed blood was reinfused at 10 min after HS. In Group III (n=7), 10 min after NG-nitro-L-arginine methyl ester 30 mg/kg intravenously (i.v.), the same procedures were performed as in Group II. In Groups II and III, although 10 min of HS produced an increase in NO-related electrical current [Group II, 2,197+/-786 pA; Group III, 983+/-77 pA (mean+/-standard error)], reinfusion of shed blood restored the NO-related electrical current to its baseline value. HF in Groups I and II decreased continuously during HS, and it recovered to baseline after the restoration from HS in Group II. In Group III, NG-nitro-L-arginine methyl ester 30 mg/kg i.v. decreased HF 12.7+/-.7 to 10.2+/-.6 mL/min/100 g (mean+/-standard error, p < .05). In conclusion, although NO produced in the liver might play an important pathophysiologic role in HS, it may not affect the blood redistribution during HS, such as in mean arterial blood pressure <40 mmHg.

Thoracic epidural block attenuates cardiovascular response to apnea in rabbits

PURPOSE

Apnea is one of the potential complications during anaesthesia. If sympathetic nerve activity is blocked by epidural anaesthesia, circulatory responses to apnea might change. Our objective was to assess the potential modifying effects of epidural anaesthesia on the cardiovascular responses to apnea in the animals.

METHODS

Twenty rabbits anaesthetised with pentobarbital (25 mg.kg-1 i.v., 8 mg.kg-1.hr-1) and pacuronium bromide (0.2 mg.kg-1.hr-1 i.v.) were randomly assigned to one of two groups: control (n = 10) and epidural (n = 10). In the control group, 0.6 ml saline, and in the epidural group, 0.6 ml lidocaine 1% was injected into the epidural space respectively. After mechanical ventilation with FIO2 0.4, apnea was induced by disconnecting the anaesthetic circuit from the endotracheal tube, and mean arterial pressure (MAP), heart rate (HR), and time to cardiac arrest were measured.

RESULTS

Before apnea MAP was lower in the epidural than in the control group (73 +/- 10 vs 91 +/- 10 mmHg, P < 0.05). Heart rate was not different between groups (264 +/- 36 vs 266 +/- 24 bpm). Mean arterial pressure increased in the control group after apnea, but not in the epidural group. The time to cardiac arrest was less in the epidural group than in the control group (420 +/- 67 vs 520 +/- 61 sec, P < 0.05). Heart rate decreased markedly after apnea in the control group whereas it decreased gradually in the epidural group.

CONCLUSION

Thoracic epidural anaesthesia attenuated cardiovascular response to apnea and reduced the time to cardiac arrest.

[Pre- and post-operative management of cesarean section in a parturient with severe preeclampsia accompanied by hyperdynamic state]

A 37-year-old parturient with severe preeclampsia accompanied by pulmonary edema underwent emergency cesarean section. Pulmonary artery (PA) catheter inserted while the patient was awake revealed hyperdynamic state with increased cardiac index and preload, and decreased systemic vascular resistance. Epidural anesthesia and analgesia were provided with a satisfactory outcome. Monitoring of PA pressure and cardiac index was continued postoperatively in ICU for fluid management. We conclude that preoperative PA catheterization provides useful hemodynamic information in severe preeclamptic patients associated with persistent oliguria, pulmonary edema and hyperdynamic state.

Nitric oxide in the brain increases during a short period of hemorrhagic shock in the rabbit

We investigated the changes in nitric oxide (NO) concentration in the brain of the rabbit by measuring NO-related electrical current. Seventeen Japanese white rabbits were anesthetized with pentobarbital sodium and mechanically ventilated with tracheotomy tubes. An NO-selective electrode was used for the detection of NO. After a round craniotomy in the left parietal lobe, an NO-sensitive electrode was placed in the brain. Rabbits were hemorrhaged to a mean arterial blood pressure of 35 +/- 7 mmHg, from a baseline of 112 +/- 12 mmHg (mean +/- SD). The shock was maintained for 5 min. The mean extracted blood volume was 77 +/- 17 mL. Then, retransfusion of shed blood caused a rapid restoration of mean arterial blood pressure. The amount of time required to induce hemorrhagic shock was 261 +/- 34 s. The time required to retransfuse the extracted blood was 233 +/- 43 s (p > .05). During shock, the NO-selective electrode produced an extensive increase in current, from 110 +/- 94.5 pA to 1010 +/- 543 pA (mean +/- SD, p < .001). The current continued to increase for a few minutes after the recovery from shock, with a maximal increase reaching 1245 +/- 515 pA (p < .001). This enhanced release of NO-related current (1,132%) recovered to the baseline level at 44 +/- 7 min after retransfusion. When the same investigation was performed on the same animals on which had been placed the same electrode pretreated with NG-nitro-L-arginine methylester (L-NAME) 30 mg/kg intravenously, NO-related current increased from 101 +/- 158 to a maximum of 860 +/- 406 pA (752%). Our results suggest that NO may play an important role in the brain during the early period of hemorrhagic shock, and that L-NAME 30 mg/kg intravenously might not inhibit the NO production in the parietal lobe, probably due to a blood-brain barrier to the nitric oxide synthase-inhibiting drug.

Comparative analysis of brain protection by N-methyl-D-aspartate receptor antagonists after transient focal ischemia in cats

OBJECTIVE

We tested the hypothesis that the administration of the competitive N-methyl-D-aspartate (NMDA) receptor antagonist 2R,4R,5S-(2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid) (NPC 17742) or cis-4-(phosphonomethyl) piperidine-2-carboxylic acid (CGS 19755) or the noncompetitive NMDA receptor antagonist dizocilpine (MK-801), at the appropriate doses, would all have efficacy in decreasing early postischemic brain injury in a feline model of transient focal ischemia.

DESIGN

Prospective, randomized, controlled animal trial.

SETTING

University research laboratory.

SUBJECTS

Forty mixed-breed cats.

INTERVENTIONS

Halothane-anesthetized cats underwent 90 mins of left middle cerebral artery occlusion plus 4 hrs of reperfusion. At 75 mins of ischemia, control cats received intravenous saline (n = 10). Experimental cats (n = 10 in each group) were treated with NPC 17742 (5 mg/kg bolus and 2.5 mg/kg/hr throughout reperfusion), MK-801 (5 mg/kg intravenous bolus), or CGS 19755 (40 mg/kg intravenous bolus) in a randomized fashion.

MEASUREMENTS AND MAIN RESULTS

Microsphere-determined blood flow to the ipsilateral inferior temporal cortex and caudate nucleus decreased to the same extent during ischemia, and recovered to the same extent during early reperfusion, in the four groups. Triphenyltetrazolium-determined injury volume of the ipsilateral caudate nucleus in cats treated with NPC 17742 (105 +/- 25 [SEM] mm3), MK-801 (97 +/- 22 mm3), and CGS 19755 (97 +/- 13 mm3) was less than in control cats (198 +/- 21 mm3). Hemisphere injury volumes with NPC 17742 (1209 +/- 405 mm3) and MK-801 (1338 +/- 395 mm3) were less than that value in controls (2193 +/- 372 mm3), whereas injury volume with CGS 19755 (1553 +/- 519 mm3) treatment did not attain significance (p < .09).

CONCLUSIONS

NMDA receptor activation during reperfusion may contribute to the progression of injury in ischemic border regions after 90 mins of transient focal ischemia in the cat. At the doses chosen, there appear to be no major differences in therapeutic efficacy for competitive and noncompetitive NMDA receptor antagonists.

The effect of head-down tilt position on arterial blood pressure after spinal anesthesia for cesarean delivery

BACKGROUND AND OBJECTIVES

The effect of the head-down tilt position after induction of spinal anesthesia for cesarean delivery on blood pressure and level of sensory block was examined.

METHODS

Patients were allocated randomly into two groups, the head-down tilt group (n = 17) and the horizontal group (n = 17). In the head-down tilt group, patients were positioned with a 10 degrees head-down tilt immediately after supine positioning, while those in the horizontal group were maintained in a horizontal position. All patients received 500 mL of lactated Ringer's solution intravenously over 10 minutes prior to spinal injection, a wedge was placed under the patient's right hip, and the operating table was rotated 5 degrees in a counterclockwise direction to provide left uterine displacement. Hypotension (defined as systolic blood pressure below 100 mm Hg) was treated with 5 mg ephedrine intravenously and an increase in the infusion rate of lactated Ringer's solution. The change in systolic blood pressure was expressed as percent change from the baseline value.

RESULTS

Systolic blood pressure decreased 20% at 3 minutes after spinal block in both groups but recovered to half of this decrease. The incidence of postspinal hypotension was not different between the two groups. The total amount of ephedrine and lactated Ringer's solution administered during the first 20 minutes of spinal block did not differ between the two groups nor did the extent of the cephalad spread of analgesia 20 minutes after spinal block (T4 +/- 2 vs T4 +/- 1 for the head-down and horizontal groups, respectively).

CONCLUSIONS

The head-down position is concluded to have no effect on the incidence of hypotension during spinal anesthesia for cesarean delivery.

A case of acute pulmonary edema and bulbar paralysis after local epinephrine infiltration

An unusual case in which pulmonary edema and intracranial hemorrhage occurred during adenotonsillectomy is presented. The possible causes of this intracranial hemorrhage are discussed, especially in relationship to local epinephrine infiltration.

Comparison of the Jackson-Rees circuit, the pediatric circle, and the MERA F breathing system for pediatric anesthesia

The purpose of this study was to compare the Jackson-Rees circuit with the pediatric circle and MERA F breathing system (MERA F system) for pediatric anesthesia from the viewpoint of work of breathing (WOB). Twenty-three children (2-10 yr old) were studied during spontaneous breathing under endotracheal anesthesia with 4 L/min nitrous oxide, 2 L/min oxygen, and 1% end-tidal concentration of sevoflurane. WOB, inspiratory and expiratory airway resistance, dynamic compliance (CDYN), pressure time product (PTP), and arterial blood gasses were measured in the three circuits. The inspiratory WOB was estimated directly by measuring the esophageal pressure-volume loop using the Campbell technique. In a laboratory study, we measured the compliances of the Jackson-Rees circuit, the pediatric circle, the MERA F system, and the adult circuit. WOB differed among the three circuits (MERA F system > pediatric circle > Jackson-Rees circuit). Inspiratory and expiratory resistances, and arterial carbon dioxide tension in the Jackson-Rees circuit were significantly lower than those of both the pediatric circle and MERA F system. The CDYN and PTP in the MERA F system were significantly higher than those in both the Jackson-Rees circuit and the pediatric circle. The MERA F system had significantly higher compliance than the Jackson-Rees circuit and pediatric circle. It is concluded that the Jackson-Rees circuit is most efficient, the pediatric circle is intermediate, and the MERA F system is the least efficient from the viewpoint of WOB during spontaneous breathing for pediatric anesthesia.

Correlation of the average water diffusion constant with cerebral blood flow and ischemic damage after transient middle cerebral artery occlusion in cats

Magnetic resonance water diffusion imaging can detect early ischemic changes in stroke. Using a middle cerebral artery occlusion model, we examined which range of values of the orientation-independent diffusion quantity Dav = 1/3Trace(D) = 1/3(Dxx + Dyy + Dzz) is an early noninvasive indicator of reduced cerebral perfusion and focal brain injury. Cats underwent either a 30-min occlusion followed by 3.5 h reperfusion (n = 7) or a 60-min occlusion followed by 4-h reperfusion (n = 6). Repeated measurements of CBF were made with radiolabeled microspheres, and acute focal injury was measured with triphenyltetrazolium chloride (TTC) staining. During occlusion, the decrease in Dav correlated with CBF for caudate [30-min occlusion (n = 13): p < 0.0001: 60-min occlusion (n = 6): p < 0.02] and for cortex [30-min occlusion (n = 12): p < 0.0001: 60-min occlusion (n = 5): p < 0.04]. Variable caudate and hemispheric injury levels were found among cats in both groups. The area of tissue injury demarcated by TTC began to correlate with the area of reduced Dav by 30 min of occlusion (p < 0.02), and this correlation improved (p < 0.0001) at 1, 1.5, and 2.0 h after the onset of occlusion. The time necessary to reach a one-to-one correspondence between the percent of hemisphere injured and the percent of hemispheric area with Dav < 0.65 x 10(-9) m2/s was 2 h after occlusion. Thus, the absolute value of Dav is a good indicator of the risk of tissue injury, whereas the combination of Dav and the length of time of Dav reduction is an excellent predictor of acute focal tissue injury demarcated by TTC staining.

[Effect of preoperative treatment with recombinant human erythropoietin in patients undergoing hemodilutional autologous transfusion]

This study evaluated whether a combination of recombinant human erythropoietin (rHuEPO) and hemodilutional autologous transfusion could reduce homologous blood transfusion in 37 patients who underwent elective urological surgery. A single dose of 6000 IU rHuEPO was administered 2 weeks before operation to patients whose preoperative hemoglobin was less than 12.0 g.dl-1 (8.5-12.0 g.dl-1) (EPO group, n = 15) and compared these with control subjects whose preoperative hemoglobin was more than 12.0 g.dl-1 (non-EPO group, n = 22). Both hemoglobin and hematocrit levels after administration of rHuEPO in the EPO group increased significantly to the same levels as in those in the non-EPO group and remained at these levels. The mean volume of donated autologous blood was 980 g in the EPO group and 110 g in the non-EPO group. The mean surgical blood loss was 1330 g in the EPO group and 1120 g in the non-EPO group. No homologous blood transfusion was required in 80 percent of the cases in both groups: however, homologous transfusions were added to 3 cases in the EPO group and 4 cases in the non-EPO group whose surgical blood loss was over 2500 g. We conclude that the combination of preoperative rHuEPO treatment and hemodilutional autologous transfusion can reduce homologous transfusion during surgery in anemic patients.