Treatment of twin-reversed arterial perfusion sequence using high-intensity focused ultrasound

We describe our experience of high-intensity focused ultrasound (HIFU) for fetal therapy in twin-reversed arterial perfusion (TRAP) sequence. Six pregnant women underwent HIFU therapy, five before 16 weeks and one at 26 weeks. Two types of HIFU system were used: the first-generation system, which comprised a biaxial transducer and continuous exposure pattern, and the second-generation system, which comprised a coaxial transducer and sequential exposure pattern. The first-generation apparatus was used in four cases and the second-generation apparatus was used in two. In three cases, occlusion of the blood vessels mediating flow to the acardiac twin was achieved by HIFU. Two cases experienced intrauterine fetal death despite vessel occlusion. The total survival rate of pump fetuses 2 years after HIFU was 67% and the efficiency rate (the proportion of cases with occlusion or reduced blood flow on ultrasound after HIFU) was 83%. After more than 2 years of follow-up, the surviving infants had no severe clinical complications and no postnatal developmental problems. There was no significant difference in survival rate compared with TRAP cases managed expectantly. Given that complete occlusion of the blood vessels was not achieved in half of the cases, we could not show that HIFU therapy is superior to other treatments. However, HIFU can reduce the cardiac load of the pump fetus and, as it does not require uterine puncture for fetal therapy, there were no fatal complications, such as bleeding, rupture of membranes or infection. Thus, HIFU therapy may represent a less-invasive treatment for TRAP sequence in early pregnancy. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Performance of the EuroSCORE II and the Society of Thoracic Surgeons Score in patients undergoing aortic valve replacement for aortic stenosis

Aim. The aim of this study was to evaluate the performance of the new European System for Cardiac Operative Risk Evaluation (EuroSCORE) II and the Society of Thoracic Surgeons (STS) score in patients undergoing aortic valve replacement (AVR) for aortic stenosis (AS). This study also evaluated the performance of the EuroSCORE II in high-risk patients. Methods. Three hundred and six consecutive adult patients underwent AVR with or without coronary artery bypass grafting at our institution from August 2002 to June 2012. The cut-off value of 6% for the EuroSCORE II and 10% for the STS score was used to identify high-risk in this study. Results. Operative mortality was 3.5% (N.=11). The mean expected mortality for all patients was 3.1% (O/E ratio=1.12) for the EuroSCORE II and 5.1% (O/E ratio=0.68) for the STS score. Observed versus expected mortality for the high-risk patients was 17.2% versus 11.9% (O/E ratio=1.44) for the EuroSCORE II (N.=29) and 19.3% versus 18.5% (O/E ratio=1.04) for the STS score (N.=31), and that for the low-risk was 2.1% versus 2.2% (O/E ratio=0.95) for the EuroSCORE II and 1.8% versus 3.5% (O/E ratio=0.51) for the STS score. Discrimination power of the STS score was good (area under the receiver operating characteristics curve [AUC] 0.74), but that of the EuroSCORE II was suboptimal (AUC 0.66). Conclusion. Good calibration ability of the EuroSCORE II for low-risk patients and that of the STS score for high-risk are observed. However, the EuroSCORE II underestimates the operative mortality in high-risk patients and the STS score overestimates the risk in low-risk patients.

The antinociceptive activity of intrathecally administered amiloride and its interactions with morphine and clonidine in rats

In this study, we aimed to evaluate the antinociceptive interaction between intrathecally administered amiloride and morphine or clonidine. Using rats chronically implanted with lumbar intrathecal catheters, we examined the ability of intrathecal amiloride, morphine, clonidine, and mixtures of amiloride-morphine and amiloride-clonidine to alter tail-flick latency. To characterize any interactions, isobolographic analysis was performed. The effects of pretreatment with intrathecally administered naloxone or yohimbine were tested. Intrathecal administration of amiloride (25-150 μg), morphine (.25-10 μg), or clonidine (.5-10 μg) alone produced significant dose-dependent antinociception in the tail-flick test. The median effective dose (ED(50)) values for intrathecally administered amiloride, morphine, and clonidine were 120.5 μg, 5.0 μg, and 4.4 μg, respectively. Isobolographic analysis exhibited a synergistic interaction after coadministration of amiloride-morphine and amiloride-clonidine. Intrathecal pretreatment with naloxone (10 μg) completely blocked the antinociceptive effects of morphine and the amiloride-morphine mixture. Intrathecal pretreatment with yohimbine (20 μg) completely blocked the antinociceptive effect of clonidine and antagonized the effect of the amiloride-clonidine mixture. There was no motor dysfunction or significant change in blood pressure or heart rate after the intrathecal administration of amiloride, amiloride-morphine, and amiloride-clonidine. The synergistic effect observed after the coadministration of amiloride and morphine or clonidine suggests a functional interaction among calcium channels, μ-receptors and α(2)-receptors at the spinal cord level of the nociceptive processing system.

PERSPECTIVE

Although intrathecal morphine and clonidine produces pronounced analgesia, antinociceptive doses of intrathecal morphine and clonidine produce several side effects, including hypotension, bradycardia, sedation, and tolerance. This article presents antinociceptive synergistic interaction between amiloride and morphine, amiloride, and clonidine on thermal nociceptive tests in the rat.

Continuous cardiac output measurement with a Doppler-equipped pulmonary artery catheter

BACKGROUND

We developed a Doppler-equipped pulmonary artery catheter that provides continuous measurement of the true main pulmonary blood flow velocity independent of the angle of incidence formed by the pulmonary artery catheter and the main pulmonary artery blood flow. This device uses 2 orthogonally positioned Doppler transducers that allow trigonometric correction for differences in the angle of blood flow between each transducer. We tested the accuracy of the Doppler-equipped pulmonary artery catheter by comparing its cardiac output measurements with those done by conventional techniques in animals.

METHODS

The Doppler-equipped pulmonary artery catheter was evaluated in dogs. A pair of ultrasound Doppler transducers positioned at a fixed angle (90°) was mounted on the distal part of the thermodilution pulmonary artery catheter. The Doppler shifts (Δf1, Δf2) were detected by the 2 transducers sampling at 2 closely spaced points in the main pulmonary artery. The values of Δf1 and Δf2 were used to compute 2 velocity measurements. The true flow velocity of the main pulmonary artery was calculated with the following equation: V(pulm) = {(V(transducer1))(2) + (V(transducer2))(2)}(1/2) (V(pulm) = true main pulmonary artery velocity; V(transducer1) and V(transducer2) = velocity detected by transducers 1 and 2, respectively). The flow velocities were calculated by using a phase differential technique. Cardiac output was calculated as V(pulm) multiplied by a coefficient value. The coefficient value was calculated by dividing cardiac output, derived from conventional techniques, by V(pulm) at the beginning of each experiment. After thoracotomy, an electromagnetic flowprobe was placed around the main pulmonary artery in dogs. Cardiac output was simultaneously measured by the Doppler-equipped pulmonary artery catheter (CO-Doppler), and the electromagnetic flowmeter (CO-EMF) or the thermodilution technique (CO-Thermo). Cardiac output was manipulated by dobutamine and propranolol.

RESULTS

CO-Doppler was highly correlated with CO-EMF (y = 1.16 × -0.26, r(2) = 0.99, P < 0.001) and CO-Thermo (y = 1.24 × -0.90, r(2) = 0.85, n = 48, P < 0.001). The bias between CO-EMF and CO-Doppler was -0.02 L/min; 95% limits of agreement were -0.32 to 0.28 L/min. The percentage error was 16%. The bias between CO-Thermo and CO-Doppler was 0.18 L/min; 95% limits of agreement were -0.62 to 0.98 L/min.

CONCLUSIONS

The newly developed Doppler-equipped pulmonary artery catheter with 2 orthogonally positioned Doppler transducers allowed accurate and continuous measurements of cardiac output independent of the angle of incidence formed by the pulmonary artery catheter and the main pulmonary artery blood flow.

Phosphorylation status of heat shock protein 27 regulates the interleukin-1β-induced interleukin-6 synthesis in C6 glioma cells

Heat shock protein 27 (HSP27), a low-molecular-weight HSP, is recognized as a molecular chaperone. In response to various stimuli, HSP27 expression is induced in the CNS. However, the exact roles of HSP27 in the CNS have not yet been clarified. It has been reported that interleukin (IL)-1β stimulates IL-6 synthesis in C6 glioma cells. In the present study, we investigated the role of HSP27 in the IL-1β-induced IL-6 synthesis in C6 cells. IL-1β alone did not affect the levels of HSP27. The IL-1β-induced IL-6 release in HSP27-downregulated C6 cells were enhanced compared with those in control siRNA-transfected cells. On the other hand, the IL-1β-induced IL-6 release was significantly enhanced in C6 cells transfected with HSP27 than those in control cells in time- and dose-dependent manner. The IL-1β-induced IL-6 release and the mRNA expression were markedly suppressed in C6 cells transfected with phosphorylated HSP27, while those in the cells transfected with unphosphorylated HSP27 were enhanced. In conclusion, these results strongly suggest that phosphorylated status of HSP27 has a switching role in the IL-1β-induced IL-6 synthesis in C6 glioma cells.

[Evaluation of urine specific gravity as an index of hypotension after spinal anesthesia for cesarean section]

BACKGROUND

Although most cesarean sections are done under spinal anesthesia, we often experience severe hypotension. Fluid resuscitation is usually carried out for prevention of hypotension, but it is difficult to assess the suitable infusion volume. We examined whether the urine specific gravity can predict hypotension after spinal anesthesia for cesarean section.

METHODS

Ninety nine patients (ASA 1 or 2) undergoing elective cesarean section were recruited. After dural puncture, we collected the cerebrospinal fluid and injected 2 ml of hyperbaric 0.5% bupivacaine. Thereafter urethral catheters were inserted, and then we collected the urine sample. The specific gravity of each sample was measured by using refractometer after the operation.

RESULTS

There was a good correlation between the urinary output and the urine specific gravity. The minimum systolic blood pressure until delivery, the total dose of ephedrine, and the maximum sensory block level showed a significant, but not particularly strong correlation with the urine specific gravity.

CONCLUSIONS

We concluded that it was difficult to predict hypotension by using urine specific gravity because the correlation was too weak.

Mechanisms of tumor necrosis factor-alpha-induced interleukin-6 synthesis in glioma cells

BACKGROUND

Interleukin (IL)-6 plays a pivotal role in a variety of CNS functions such as the induction and modulation of reactive astrogliosis, pathological inflammatory responses and neuroprotection. Tumor necrosis factor (TNF)-alpha induces IL-6 release from rat C6 glioma cells through the inhibitory kappa B (IkappaB)-nuclear factor kappa B (NFkappaB) pathway, p38 mitogen-activated protein (MAP) kinase and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK). The present study investigated the mechanism of TNF-alpha-induced IL-6 release in more detail than has previously been reported.

METHODS

Cultured C6 cells were stimulated by TNF-alpha. IL-6 release from the cells was measured by an enzyme-linked immunosorbent assay, and the phosphorylation of IkappaB, NFkappaB, the MAP kinase superfamily, and signal transducer and activator of transcription (STAT)3 was analyzed by Western blotting. Levels of IL-6 mRNA in cells were evaluated by real-time reverse transcription-polymerase chain reaction.

RESULTS

TNF-alpha significantly induced phosphorylation of NFkappaB at Ser 536 and Ser 468, but not at Ser 529 or Ser 276. Wedelolactone, an inhibitor of IkappaB kinase, suppressed both TNF-alpha-induced IkappaB phosphorylation and NFkappaB phosphorylation at Ser 536 and Ser 468. TNF-alpha-stimulated increases in IL-6 levels were suppressed by wedelolactone. TNF-alpha induced phosphorylation of STAT3. The Janus family of tyrosine kinase (JAK) inhibitor I, an inhibitor of JAK 1, 2 and 3, attenuated TNF-alpha-induced phosphorylation of STAT3 and significantly reduced TNF-alpha-stimulated IL-6 release. Apocynin, an inhibitor of NADPH oxidase that suppresses intracellular reactive oxygen species, significantly suppressed TNF-alpha-induced IL-6 release and mRNA expression. However, apocynin failed to affect the phosphorylation of IkappaB, NFkappaB, p38 MAP kinase, SAPK/JNK or STAT3.

CONCLUSION

These results strongly suggest that TNF-alpha induces IL-6 synthesis through the JAK/STAT3 pathway in addition to p38 MAP kinase and SAPK/JNK in C6 glioma cells, and that phosphorylation of NFkappaB at Ser 536 and Ser 468, and NADPH oxidase are involved in TNF-alpha-stimulated IL-6 synthesis.

Mechanisms of interleukin-1beta-induced GDNF release from rat glioma cells

Glial cell line-derived neurotrophic factor (GDNF) is highly expressed both in neurons and astrocytes in injured tissues. Astrocytes support neurons by releasing neurotrophic factors including GDNF. It has been reported that various agents including cytokines such as interleukin (IL)-1beta induce GDNF mRNA expression and the release in astrocytes. However, the mechanism behind the GDNF synthesis and release remains unclear. Herein, we investigated the mechanisms of the IL-1beta-induced GDNF release from rat C6 glioma cells. IL-1beta time dependently stimulated GDNF release from C6 cells. IL-1beta induced the phosphorylation of inhibitor kappa B (IkappaB), p38 mitogen-activated protein (MAP) kinase, p44/p42 MAP kinase, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) and signal transducer and activator of transcription (STAT) 3. The IL-1beta-stimulated levels of GDNF were suppressed by wedelolactone, an inhibitor of IkappaB kinase, SB203580, an inhibitor of p38 MAP kinase, PD98059, an inhibitor of MAP kinase kinase 1/2 or Janus family of tyrosine kinase (JAK) inhibitor I, an inhibitor of upstream kinase of STAT3. On the contrary, SP600125, an inhibitor of SAPK/JNK, failed to reduce the IL-1beta-effect. These results strongly suggest that IL-1beta stimulates GDNF release through the pathways of IkappaB-nuclear factor kappa B, p38 MAP kinase, p44/p42 MAP kinase and JAK-STAT3, but not through the SAPK/JNK pathway in glioma cells.

[Case of pulmonary edema and transient heart failure during difficult airway management]

Many kinds of side effects are likely to occur while managing difficult airway. This article describes a case of a man who fell into pulmonary edema and heart failure during the difficult airway management. He was to undergo arthroscopic surgery on his knee. At first, we planed spinal anesthesia but he took an antiplatelet drug (aspirin). Since we wanted to avoid the epidural hematoma, we chose general anesthesia. After induction of general anesthesia, positive pressure ventilation via face mask was possible, but laryngeal mask ventilation was impossible. Although tracheal intubation was attempted, we recognized that he had difficult airway. After some intubation trials, we decided to quit the operation and awoke the patients. Spontaneous breathing appeared soon, but the oxygenation was getting worse. We performed fiberoptic nasal intubation under spontaneous breathing. Although his blood pressure was quite high during intubation, after intubation the vasopressor was needed to maintain blood pressure. Ventilation with 100% O2 could not maintain the oxygenation well. Chest X-ray revealed the pulmonary edema. We presumed that hypertension associated with airway stimulation had caused acute pulmonary edema and heart failure resulting from diastolic dysfunction induced by increased catecholamine.

[Off-pump coronary artery bypass grafting as standard operation; surgical strategies and results]

We report the clinical results of 799 cases of isolated coronary artery bypass grafting (CABG) performed during the recent 5 years. We performed off-pump CABG (OPCAB) as standard operation, in which arterial grafts were mainly used. The mean number of distal anastomoses was 3.6 +/- 1.4 per patient Four hundred and fifty-five cases (57.0%) were done only with arterial grafts. Bilateral internal thoracic arteries were used in 326 cases. The mean number of saphenous vein grafts was 1.6 +/- 0.8 per patient. Continuous hemodiafiltraion (CHDF) was performed in 22 cases (2.8%) postoperatively. Among the OPCAB cases, 10 cases (1.3%) were converted to on-pump CABG. There were 7 cases (0.9%) of hospital death. The mean length of postoperative hospital stay was 10.2 +/- 5.3 days. The ratio of the patients with left main trunk disease and that of the patients who required postoperative CHDF increased year by year. The mean length of postoperative hospital stay decreased every year, and the reduced length was 2.7 days in the 5 years (8.7+/- 3.6 days in 2007). It is expected that patients who have severe calcified lesions or who are on hemodialysis may increase in the near future. In such cases, CABG rather than percutaneous catheter intervention may be suitable for revascularization. Therefore, not only appropriate choice of treatment strategies, but also accurate surgical techniques may become more importance.

[Postoperative epidural hematoma remote from the site of craniotomy for STA-MCA anastomosis]

We experienced a case in which the cause of acute brain swelling following resection of dura matter could not be recognized until the postoperative CT scan. A 30-year-old woman presented with a 4-year history of Moyamoya disease. Right hemiplegia developed a month before operation, so that the anti-platelet therapy was continued. At the end of dural resection the brain started to bulge and the brain swelling increased progressively. The patient was immediately placed on a head up position and received a rapid administration of mannitol for the treatment. The operator performed the echo examination for clarifying the cause of the brain swelling, but they could not find it. As the brain swelling slightly improved by the treatment, the surgery was performed continuously At the end of the operation the patient was moved for a CT scan and it showed mass effect caused by epidural hematoma over the left temporal region distant from the site of craniotomy. Evacuation of the hematoma was carried out urgently. At discharge, she was conscious and had no focal neurological deficits. The occurrence of the epidural hematoma is one of the reasons for unknown brain swelling during surgery. We strongly recommend that any sudden deterioration during the operation should be treated with emergency CT scan.

Alpha2 adrenoreceptor agonist regulates protein kinase C-induced heat shock protein 27 phosphorylation in C6 glioma cells

Dexmedetomidine (Dexmd), a potent and highly specific alpha(2) adrenoreceptor agonist, is an efficient therapeutic agent for sedation. Dexmd has been recently reported to have a neuroprotective effect. Heat shock protein (HSP) 27, a low-molecular weight HSP has been shown to be expressed following cerebral ischemia in astrocytes but not in neurons. HSP27 expression is involved in ischemic tolerance of the brain. This study investigated the effect of Dexmd on HSP27 in rat C6 glioma cells. 12-O-tetradecanoylphorbol-13-actate (TPA), a direct activator of protein kinase C (PKC), stimulated the phosphorylation of HSP27 at Ser82, but not Ser15 in a time-dependent manner. Prostaglandin (PG) E(1) or PGE(2) which activates the adenylyl cyclase-cAMP system as well as forskolin and dibutyryl-cAMP, suppressed the TPA-induced phosphorylation of HSP27. Dexmd reversed the suppression of HSP27 phosphorylation by the adenylyl cyclase-cAMP system. Therefore, these results strongly suggest that Dexmd reverses the suppression of HSP27 phosphorylation by the adenylyl cyclase-cAMP system activation through the inhibition of its system in C6 cells. alpha(2) Adrenoreceptor agonists may therefore show a neuroprotective effect through the modification of HSP27 phosphorylation induced by PKC activation.

[Use of high-dose dexmedetomidine infusion for anesthesia and sedation in a patient for microlaryngeal surgery maintained with spontaneous breathing]

We experienced the anesthetic management using high-dose dexmedetomidine for microlaryngeal surgery maintaining spontaneous breathing. The anesthesia was maintained with dexmedetomidine infusion (initial dose 6 microg x kg(-1) x hr(-1) over 10 min followed by continuous infusion of 0.5 microg x kg(-1) x hr(-1)), intermittent small doses of fentanyl and topical application of lidocaine on the tongue, pharynx and larynx. The infusion of dexmedetomidine was increased over 30 min to 3 microg x kg(-1) x hr(-1) to reach the adequate sedation level and maintained at this rate for a further 15 min during the operation. During the whole perioperative period, there was no respiratory depression as measured by arterial blood gas analysis that recorded normal PaCO2 in the patient breathing supplemental oxygen. Hypotension (systemic arterial blood pressure less than 100 mmHg) occurred twice during dexmedetomidine administration, but was normolized by ephedrine administration. The preservation of respiratory drive offers the possibility that this anesthetic technique may be another method for providing anesthesia for the patient with a difficult airway. Moreover, there is one consensus on the importance of the basic principle that adequate topical or intravenous anesthesia is also essential during high-dose dexmedetomidine infusion.

Rho-kinase inhibitor and Nicotinamide Adenine Dinucleotide PHosphate oxidase inhibitor prevent impairment of endothelium-dependent cerebral vasodilation by acute cigarette smoking in rats

Introduction. We previously reported that acute cigarette smoking can cause a dysfunction of endothelium-dependent vasodilation in cerebral vessels, and that blocking the angiotensin II (Ang II) type 1 (AT1) receptor with valsartan prevented this impairment. Our aim was to investigate the effects of a Rho-kinase inhibitor (fasudil) and a Nicotinamide Adenine Dinucleotide PHosphate (NADPH) oxidase inhibitor (apocynin) on smoking-induced endothelial dysfunction in cerebral arterioles.

Method. In Sprague—Dawley rats, we used a closed cranial window preparation to measure changes in pial vessel diameters following topical acetylcholine (ACh) before smoking. After one-minute smoking, we again examined the arteriolar responses to ACh. Finally, after intravenous fasudil or apocynin pre-treatment we re-examined the vasodilator responses to topical ACh (before and after cigarette smoking).

Results. Under control conditions, cerebral arterioles were dose-dependently dilated by topical ACh (10-6 M and 10-5 M). One hour after a one-minute smoking (1 mg-nicotine cigarette), 10-5 M ACh constricted cerebral arterioles. However, one hour after a one-minute smoking, 10-5 M ACh dilated cerebral pial arteries both in the fasudil pre-treatment and the apocynin pre-treatment groups, responses that were significantly different from those obtained without fasudil or apocynin pre-treatment.

Conclusion. Thus, inhibition of Rho-kinase and NADPH oxidase activities may prevent the above smoking-induced impairment of endothelium-dependent vasodilation.

Antinociceptive Synergistic Interaction Between Clonidine and Ouabain on Thermal Nociceptive Tests in the Rat

The antinociceptive effect produced by spinal injection of clonidine (an alpha(2)-adrenergic agonist) is mediated by a cholinergic mechanism. We aimed in the current study to evaluate the antinociceptive interaction between intrathecally administered ouabain, an inhibitor of Na(+), K(+)-ATPase, and clonidine. We used rats chronically implanted with lumbar intrathecal catheters to examine the ability of intrathecal clonidine and ouabain and the mixtures of clonidine-ouabain to alter tail-flick latency. To characterize the interaction, isobolographic analysis was performed. Intrathecal clonidine (0.5-10 microg) and ouabain (0.1-5 microg) produced significant dose- and time-dependent antinociception in the tail-flick tests. The median effective dose (ED(50)) values for intrathecally administered ouabain and clonidine were 2.3 microg and 4.7 microg, respectively. The experimental point for the ouabain-clonidine combination decreased significantly (P < .05) below the lines of additivity. Isobolographic analysis exhibited a synergistic interaction after the coadministration of ouabain and clonidine. No motor impairment was observed in the animals after intrathecal administration of the combination of ouabain and clonidine or clonidine alone. Intrathecal pretreatment with atropine but not yohimbine blocked the antinociceptive effect of ouabain and attenuated its interaction with spinal clonidine. These results suggest that the synergistic interaction of ouabain and clonidine were probably mediated, at least in part, via an enhancement of cholinergic transmission in the spinal nociceptive processing system.

PERSPECTIVE

Although intrathecal clonidine produces pronounced analgesia, antinociceptive doses of intrathecal clonidine produce several side effects, including hypotension, bradycardia, and sedation. This article presents antinociceptive synergistic interaction between clonidine and ouabain on thermal nociceptive tests in the rat.

Human atrial natriuretic peptide prevents the increase in pulmonary artery pressure associated with aortic unclamping during abdominal aortic aneurysmectomy

OBJECTIVE

To assess the effect of human atrial natriuretic peptide (HANP) on the pulmonary and systemic circulations during infrarenal abdominal aortic aneurysmectomy.

DESIGN

A prospective, randomized study.

SETTING

A university hospital.

PARTICIPANTS

Forty-five patients undergoing infrarenal abdominal aortic aneurysmectomy.

INTERVENTIONS

Abdominal aortic aneurysmectomy patients were randomly assigned to 1 of 3 groups (n = 15 for each group). They were infused with normal saline solution (SA), 0.02 microg/kg/min of HANP (LH), or 0.05 microg/kg/min of HANP (HH), starting 5 minutes after clamping. Hemodynamic variables were measured before/after clamping and unclamping.

MEASUREMENTS AND MAIN RESULTS

Both mean pulmonary arterial pressure (MPAP) and the pulmonary vascular resistance index (PVRI) increased (v baseline) in the SA group. HANP attenuated the rises in MPAP and PVRI dose dependently (LH and HH groups v SA). Mean arterial pressure and systemic vascular resistance index were not significantly different among the 3 groups.

CONCLUSION

HANP, infused during aortic clamping and abdominal aortic aneurysmectomy, attenuates the rises in pulmonary artery pressure and vascular resistance without severe systemic hypotension. This may result from direct and/or indirect pulmonary vascular effects of HANP because no HANP-induced changes in endothelin-1, angiotensin-II, and thromboxane B(2) were detected.

Effects of ifenprodil on voltage-gated tetrodotoxin-resistant Na+ channels in rat sensory neurons

BACKGROUND AND OBJECTIVE

To examine a possible mechanism for the antinociceptive action of the N-methyl-D-aspartate receptor antagonist ifenprodil, we compared its effects with those of ketamine on tetrodotoxin-resistant Na+ channels in rat dorsal root ganglion neurons, which play an important role in the nociceptive pain pathway.

METHODS

Experiments were performed on dorsal root ganglion neurons from Sprague-Dawley rats, recordings of whole-cell membrane currents being made using patch-clamp technique.

RESULTS

Both drugs blocked tetrodotoxin-resistant Na+ currents dose dependently, their half-maximal inhibitory concentrations being 145+/-12.1 micromol (ketamine) and 2.6+/-0.95 micromol (ifenprodil). Ifenprodil shifted the inactivation curve for tetrodotoxin-resistant Na+ channels in the hyperpolarizing direction and shifted the activation curve in the depolarizing direction. Use-dependent blockade of tetrodotoxin-resistant Na+ channels was more marked with ifenprodil than with ketamine. When paired with lidocaine, these drugs produced similar additive inhibitions of tetrodotoxin-resistant Na+ channel activity.

CONCLUSIONS

The observed suppressive effects on tetrodotoxin-resistant Na+ channel activity may, at least in part, underlie the antinociceptive effects of these N-methyl-D-aspartate receptor antagonists.

Effects of alpha2-adrenoceptor agonists on tetrodotoxin-resistant Na+ channels in rat dorsal root ganglion neurons

BACKGROUND AND OBJECTIVE

When intrathecally or epidurally administered, alpha2-adrenoceptor agonists produce potent antinociception by affecting the activity of primary afferent fibres and spinal cord neurons. Recent reports have indicated that in dorsal root ganglion neurons, tetrodotoxin-resistant Na+ channels play important roles in the conduction of nociceptive sensation. We therefore investigated the effects of alpha2-adrenoceptor agonists on tetrodotoxin-resistant Na+ currents.

METHODS

Using the whole-cell patch-clamp technique, we recorded tetrodotoxin-resistant Na+ currents from rat dorsal root ganglion neurons.

RESULTS

Both clonidine and dexmedetomidine reduced the peak amplitude of the tetrodotoxin-resistant Na+ current concentration- and use-dependently. The concentration required for a half-maximal effect was significantly lower for dexmedetomidine (58.0 +/- 10.2 micromol) than for clonidine (257.2 +/- 30.9 micromol) at holding potential -70 mV. The current inhibitions induced by these agonists were not prevented by 1 micromol yohimbine, an alpha2-adrenoceptor antagonist. Both clonidine and dexmedetomidine shifted the inactivation curve for the tetrodotoxin-resistant Na+ current in the hyperpolarizing direction. The combinations clonidine with lidocaine and dexmedetomidine with lidocaine produced an additive blockade-type interaction on the tetrodotoxin-resistant Na+ current.

CONCLUSIONS

The results suggest that a direct inhibition of tetrodotoxin-resistant Na+ channels may contribute to the antinociceptive effects of clonidine and dexmedetomidine when used as additives to regional anaesthesia.

Effects of Pericardial Lidocaine on Hemodynamic Parameters and Responses in Dogs Anesthetized With Midazolam and Fentanyl

OBJECTIVE

Tachycardia during anesthesia should be avoided, especially during off-pump coronary artery bypass graft surgery. Decreasing heart rate without reducing cardiac contractility is an ideal goal. To achieve this, the authors attempted to block the cardiac nerves by pericardial administration of local anesthetic.

DESIGN

A prospective study.

SETTING

A laboratory.

PARTICIPANTS

Anesthetized, mechanically ventilated dogs (n = 69).

INTERVENTIONS

The pericardial space was infused with 2.5 or 5 mL of 1% lidocaine, 5 mL of 2% lidocaine, or normal saline solution. The hemodynamic changes and the cardiac responses to atropine or isoproterenol were measured during cardiac nerve blockade. To examine the inhibitory action of pericardial lidocaine on arrhythmias, an electrical fibrillator was installed. Furthermore, the blood level of lidocaine was measured.

MEASUREMENTS AND MAIN RESULTS

Pericardial injection of lidocaine significantly decreased heart rate without a change in stroke volume. Under pericardial lidocaine, the tachycardia response to isoproterenol was similar to that observed without pericardial lidocaine, but response to atropine was significantly reduced. Pericardial lidocaine increased the voltage thresholds for inducing arrhythmias and ventricular fibrillation. Intravenous injection of lidocaine elevated the plasma concentration of lidocaine immediately, whereas the plasma concentration peaked at 10 minutes after pericardial administration.

CONCLUSIONS

Pericardial lidocaine (1) decreased heart rate without affecting stroke volume, (2) preserved the tachycardiac response to isoproterenol but completely blocked the response to atropine, and (3) increased the voltage thresholds for arrhythmias and ventricular fibrillation induced by an electrical fibrillator. These results suggest that pericardial lidocaine may be useful for controlling heart rate during off-pump coronary artery bypass graft surgery.

Identification of independent predictors for intravenous thiopental-induced yawning

PURPOSE

To explore risk factors for the yawning response induced by the intravenous administration of thiopental during the induction of general anesthesia.

METHODS

We analyzed data from a cohort of 1322 patients who underwent elective surgery under general anesthesia plus intravenous thiopental. The data collected were: (a) the patients' demographic findings (age, sex, height, weight, cigarette smoking, hypertension, and presence of cerebral lesion), and (b) anesthesia-related findings (the kind of preanesthetic medication, i.e., atropine, epidural lidocaine, priming dose of vecuronium, fentanyl, and the dose of intravenous thiopental). An association between an individual variable in the evaluation model and the likelihood of thiopental-induced yawning behavior was characterized by means of the odds ratio. Multiple logistic regression was used to examine the independent contribution of each candidate variable, while controlling for all variables.

RESULTS

After the intravenous administration of thiopental, 461 patients exhibited a yawning response. The probability of this response was decreased by the prior use of intravenous fentanyl, by female sex, and by premedication with clonidine, but the probability was unaffected by premedication with hydroxyzine, by the prior use of atropine, or by the presence of hypertension or a cerebral lesion.

CONCLUSION

Thiopental-induced yawning may be suppressed by female sex, prior use of intravenous fentanyl, and premedication with clonidine. These findings may allow insights into the physiologic and pharmacological aspects of yawning in humans, thereby leading to the development methods to prevent thiopental-induced yawning.

The comparative effects of intravenous nicardipine and prostaglandin E1 on the cerebral pial arteriolar constriction seen after unclamping of an aortic cross-clamp in rabbits

BACKGROUND

The potent vasodilators nicardipine and prostaglandin E1 (PGE1) are useful for the treatment of systemic hypertension or pulmonary hypertension during aortic surgery.

METHODS

We measured cerebral pial arteriolar diameters, using a rabbit closed cranial window preparation: before (baseline) and 15 min after the start of an IV infusion (preclamp) (0.9% saline [control group], nicardipine [at 0.1, 1.0, or 10 microg x kg(-1) x min(-1)], or PGE1 [at 0.1 or 1.0 microg x kg(-1) x min(-1)]), just after aortic clamping, 20 min after clamping, and at 0-60 min after unclamping.

RESULTS

In the control group, a significant decrease in diameter persisted for at least 60 min after unclamping (maximum [at 60 min], -16% for large [> or =75 microm], and -27% for small [<75 microm] arterioles versus baseline). Although the aortic unclamping-induced vasoconstriction was unaffected under the smallest dose of nicardipine, it was significantly attenuated under larger doses in both large and small arterioles (residual vasoconstriction, -10% and -6% for large and -18% and -10% for small arterioles; at 60 min). The pial arteriolar constriction observed at 5 min or more after unclamping in the control group was not altered by PGE1 in either large or small arterioles.

CONCLUSIONS

The larger doses of nicardipine, but neither dose of PGE1, attenuated aortic unclamping-induced sustained cerebral pial arteriolar constriction.

Identification of independent risk factors for fentanyl-induced cough

PURPOSE

To determine how the probability of fentanyl-induced cough is affected by patient characteristics and/or anesthetic technique.

METHODS

We analyzed data from a cohort of 1,311 adult patients undergoing elective surgery under general anesthesia, accompanied by i.v. fentanyl. The following data were collected: patient demographics, history of cigarette smoking, presence of bronchial asthma or chronic obstructive pulmonary disease, administration of angiotensin converting enzyme inhibitors; and anesthetic technique, including: preanesthetic anxiolytic medication, prior use of atropine, epidural lidocaine, a priming dose of vecuronium, and the dose of i.v. fentanyl. Associations between individual variables in the clinical evaluation model and the likelihood of fentanyl-induced cough were characterized by calculating odds ratios. Multiple logistic regression analysis was used to examine the independent contribution of each variable while controlling for all variables.

RESULTS

Fentanyl-induced cough was independently associated with the following: aging, cigarette smoking, a prior epidural injection of lidocaine, and a priming dose of vecuronium. Fentanyl-induced cough was unaffected by gender, the presence of either bronchial asthma or chronic obstructive pulmonary disease, or prior use of atropine.

CONCLUSIONS

Fentanyl-induced cough may be suppressed by aging, cigarette smoking, prior epidural injection of lidocaine, or a priming dose of vecuronium. These findings may allow insights into the mechanism of this phenomenon, thereby leading to its prevention.

Modulation by the steroid/thyroid hormone superfamily of TGF-beta-stimulated VEGF release from vascular smooth muscle cells

We previously reported that transforming growth factor-beta (TGF-beta) stimulates the release of vascular endothelial growth factor (VEGF) from aortic smooth muscle A10 cells via activation of p38 mitogen-activated protein (MAP) kinase. In the present study, we investigated whether nuclear hormone receptor superfamily members affect TGF-beta-stimulated VEGF release from A10 cells. Retinoic acid or 1,25-dihydroxyvitamin D3 enhanced TGF-beta-induced VEGF release in a concentration-dependent manner, whereas dexamethasone or corticosterone suppressed TGF-beta-induced VEGF release. 1,25-Dihydroxyvitamin D3 and TGF-beta stimulated phosphorylation of p38 MAP kinase in an additive manner. SB203580, an inhibitor of p38 MAP kinase, decreased the VEGF release induced by TGF-beta or 1,25-dihydroxyvitamin D3. However, retinoic acid, dexamethasone, or corticosterone did not affect phosphorylation of p38 MAP kinase. These results indicate that retinoic acid, 1,25-dihydroxyvitamin D3, and glucocorticoids affect TGF-beta-stimulated VEGF release from aortic smooth muscle cells. The stimulatory effect of 1,25-dihydroxyvitamin D3 occurs, in part, via modification of TGF-beta-induced activation of p38 MAP kinase.

Epidural morphine injection after combined spinal and epidural anaesthesia

BACKGROUND AND OBJECTIVE

Although combined spinal and epidural anaesthesia is efficient and easy to perform, the technique can be a double-edged sword having the potential risk that an increased flux of drugs across the meninges through the hole made in it may lead to severe adverse effects. The aim was to compare the incidence of adverse events when an epidural injection of morphine was given after combined spinal and epidural anaesthesia or after epidural anaesthesia.

METHODS

Fifteen patients had an epidural catheter inserted at the L2-3 interspace, and then a spinal block administered via the L3-4 interspace. Another 15 patients only had an epidural catheter inserted. After the onset of spinal or epidural anaesthesia had been confirmed, morphine 2 mg was injected into the epidural space, and a continuous epidural infusion of morphine was started. At the end of the operation and at 4, 8 and 12 h after the administration of epidural morphine and on the next day, the following variables were examined: blood pressure, heart rate, respiratory rate, arterial blood-gas analysis, visual analogue scale pain scores, nausea/vomiting scores, and pruritus scores.

RESULTS

In the study population, the epidural injection of morphine was not associated with a significantly higher incidence of adverse events when given after spinal anaesthesia than after epidural anaesthesia.

CONCLUSIONS

The adverse effects associated with epidural morphine given after spinal anaesthesia did not increase significantly when a 27-G Whitacre needle was used. Thus, the morphine flux through the meningeal hole into the cerebrospinal fluid was trivial.

Effects of dexmedetomidine on cerebral circulation and systemic hemodynamics after cardiopulmonary resuscitation in dogs

PURPOSE

Our purpose was to examine the effect of dexmedetomidine, when used with phenylephrine during cardiopulmonary resuscitation (CPR), on the cerebral and systemic circulations.

METHODS

In pentobarbital-anesthetized, mechanically ventilated dogs, we evaluated pial vessel diameters, cerebral oxygen extraction, and systemic hemodynamics before and after cardiac arrest (5 min) and resuscitation, in the presence or absence of dexmedetomidine (n = 7 each; dexmedetomidine or control group).

RESULTS

In both groups: (a) pial arterioles were dilated at 5 and 15 min after CPR, and had returned to baseline diameters at 30 min; (b) sagittal sinus pressure was significantly raised at 5 and 15 min after CPR; and (c) cerebral oxygen extraction was decreased at 5, 15, and 30 min after CPR, and had returned to baseline level at 60 min after CPR. We could find no differences between the two groups in the cerebral circulation after CPR. However, the number of defibrillation electric shocks required to restore spontaneous circulation (5.5 vs 3.6; P < 0.05), the dose of phenylephrine used for CPR (1193 microg vs 409 microg; P < 0.01), and the number of postresuscitation ventricular ectopic beats observed during the first 120 min after successful resuscitation (1606 vs 348; P < 0.05) were all significantly lower in the dexmedetomidine group.

CONCLUSION

Although intravenous dexmedetomidine, as used for CPR, does not have a beneficial effect on either cerebral vessels or cerebral oxygen extraction, it may reduce the number of defibrillation shocks needed and the number of postresuscitation ventricular ectopic beats, and help to bring about stable systemic circulation after CPR.

Modified nasal cannula for simultaneous oxygen delivery and end-tidal CO2 monitoring during spontaneous breathing

BACKGROUND AND OBJECTIVES

Supplemental oxygen is commonly given via nasal cannulae in spontaneously breathing patients. Our modified nasal cannula with a clamp between the nasal prongs can provide O2 via one nostril and CO2 can be sampled through the other one. We have studied whether this cannula can provide oxygenation similar to a standard cannula without affecting end-tidal CO2 monitoring.

METHODS

Eighty-six patients were studied during spinal anaesthesia and sedation. In 15 patients, arterial blood was sampled while O2 was delivered at flow rates of 0, 2 and 4 L min(-1), with or without clamping between the prongs of our modified nasal cannula. In the remaining 71 patients, arterial O2 was measured while using our modified nasal cannula with the clamp applied. End-tidal CO2 was recorded on a capnograph and the correlation between end-tidal and arterial values with our modified nasal cannula was investigated.

RESULTS

No end-tidal CO2 waveforms were found with oxygen flow greater than 2L min(-1) without clamping between the prongs. With clamping there was a significant correlation (r = 0.83) between arterial and end-tidal CO2. A Bland-Altman analysis revealed a bias of 0.49 kPa with precision of +/-0.76 kPa. Arterial oxygenation was not affected by our modified nasal prongs with clamp as compared to the standard cannula.

CONCLUSION

Our modified nasal cannula can provide continuous monitoring of end-tidal CO2 without affecting oxygen delivery in sedated, spontaneously breathing patients.

Angiotensin II type 1 (AT1)-receptor blocker prevents impairment of endothelium-dependent cerebral vasodilation by acute cigarette smoking in rats

Our aim was to test for smoking-induced endothelial dysfunction in rat cerebral vessels, then to evaluate the effect of valsartan [angiotensin II type I (AT1)-receptor blocker] on that impairment. In pentobarbital-anesthetized, mechanically ventilated Sprague-Dawley rats, we used a cranial window preparation to measure changes in pial vessel diameters following topical applications of acetylcholine (Ach) (before and after smoking or intravenous nicotine infusion; n = 6 in each group), and adenosine (n = 6 for before and after smoking). Then, after intravenous valsartan pretreatment we reexamined the pial vasodilator response to topical Ach (before and after cigarette smoking). Under control conditions, cerebral arterioles were dilated by 6.9 +/- 4.2% and 13.6 +/- 4.8% by topical Ach (10(-6) M and 10(-5) M, respectively) and by 6.4 +/- 2.5% and 12.2 +/- 3.1% by topical adenosine (10(-5) M and 10(-4) M, respectively). One hour after a 1-min inhalation of mainstream smoke (1-mg nicotine cigarette), 10(-5) M Ach constricted cerebral arterioles (-4.4 +/- 4.1%), while 10(-4) M adenosine dilated them by 13.4 +/- 3.4%. One hour after a 1-min nicotine infusion (0.05 mg), 10(-5) M Ach dilated cerebral arterioles by 9.9 +/- 2.4%. Thus, vasodilator response to topical Ach was impaired after smoking, whereas that to adenosine was unaffected. However, the vasodilator response to Ach was unaffected by intravenous nicotine. Valsartan prevented smoking from impairing Ach-induced vasodilation. In conclusion, acute single-cigarette smoking causes a dysfunction of endothelium-dependent, but not endothelium-independent, vasodilation of rat cerebral vessels in vivo, and the effect was not mimicked by intravenous nicotine. AT1-receptor blockade prevented the above smoking-induced impairment of endothelium-dependent vasodilation.

Does yawning represent a transient arousal-shift during intravenous induction of general anesthesia?

Although yawning occurs frequently during the IV induction of general anesthesia, the significance of this response remains unknown. In this study, we induced 30 surgical patients with 4 mg/kg thiopental IV, and 30 patients with 2 mg/kg propofol IV. Thereafter, the occurrence of yawning was continuously assessed, as the only clinical end-point, for 1 min. The electroencephalographic bispectral index was monitored throughout the observation period. The criterion for an arousal response was a transient increase during a continuing decrease in the bispectral index value. On the basis of this criterion, the sensitivity and specificity of the yawning response as an arousal sign were 77% and 80%, respectively. If a patient exhibited a yawning response, the chance of arousal was 84% (positive predictive value). With no yawning response, the chance of nonarousal was 71% (negative predictive value). According to simple logistic regression, the yawning response was predictive of a transient arousal-shift with an odds ratio of 13.5 (95% confidence interval: 3.8-48; P < 0.001). The occurrence of a yawning response during IV induction may be a clinical indicator of a transient arousal-shift during progressive loss of consciousness.

IMPLICATIONS

Yawning elicited by IV anesthetic induction was related to a transient increase during the continuing decrease in the electroencephalographic bispectral index value (sensitivity and specificity, 77% and 80%, respectively). This type of yawning may be a clinical indicator of a transient arousal-shift during progressive loss of consciousness.

Periorbital pain associated with hemifacial spasms that responded to botulinum toxin treatment and microvascular decompression surgery: a case report

Periorbital pain is unusual in patients with blepharospasms. We report a patient with hemifacial spasms who presented with severe ipsilateral periorbital aching pain. After treatment with botulinum toxin type A, the left hemifacial spasms and left periorbital pain improved temporarily. Microvascular decompression surgery was then performed for the facial spasms. The patient's left hemifacial spasms disappeared immediately after the operation, and his left periorbital pain was also totally resolved.

Both milrinone and colforsin daropate attenuate the sustained pial arteriolar constriction seen after unclamping of an abdominal aortic cross-clamp in rabbits

We previously reported that unclamping of an abdominal aortic cross-clamp causes initial dilation of pial arteries followed by sustained constriction. Both milrinone and colforsin daropate have a vasodilator action, and both have been used in such critical conditions as abdominal aortic aneurysmectomy. We measured cerebral pial arteriolar diameters using a rabbit closed cranial window preparation before (baseline) and 15 min after the start of an IV infusion of 0.9% saline (control group), milrinone, or colforsin daropate (0.05 and 0.5 microg . /kg(-1) . min(-1)) (pre-clamp), just after aortic clamping, 20 min after clamping, and at 0 to 60 min after unclamping. In the control group, a significant decrease in diameter persisted for at least 60 min after unclamping (maximum, -15% for large and -26% for small arterioles versus baseline). These values were significantly smaller after both doses of milrinone and the larger dose of colforsin daropate (-5% and -8%, 10% and 12%, and -2% and -5%, respectively vs baseline, at 60 min). In a second experiment, changes in regional cerebral blood flow and tissue oxygen tension reflected changes in vascular variables. Thus, sustained cerebral pial arteriolar constriction induced by aortic unclamping can be attenuated by IV milrinone or colforsin daropate.

[Bilateral recurrent laryngeal nerve paralysis in a child following a neurosurgical operation]

We experienced a case of 7-year-old boy who developed bilateral recurrent laryngeal nerve paralysis following an elective neurosurgical operation under oxygen-nitrous oxide-isoflurane anesthesia. He underwent a removal of brain tumor in the supratentorial region on supine position. After the removal of the endotracheal tube in the intensive care unit, he developed marked respiratory effort and inspiratory stridor. A diagnosis of bilateral recurrent laryngeal nerve paralysis was made by a direct diagnostic laryngoscopy. The patient needed continuous care for his airway patency with tracheotomy tube in place, and his normal vocal cord mobility recovered on the 23 rd postoperative day. Common cause of recurrent nerve injury following general anesthesia is either the procedure of endotracheal intubation itself or trauma due to surgical manipulation. In the present case, an endotracheal tube, a transesophageal stethoscope and a nasogastric tube inserted into the narrow laryngeal space might have been a cause of this complication. Moreover, accidental extreme flexion of his neck which occurred during the surgery might also be an additional cause. This case suggests that recurrent laryngeal nerve paralysis due to anesthetic instruments around the larynx is a possible cause of complications during general anesthesia in pediatric patients.

Possible involvement of p44/p42 MAP kinase in retinoic acid-stimulated vascular endothelial growth factor release in aortic smooth muscle cells

Retinoic acid modulates cell growth and differentiation of the vascular system. Vascular endothelial growth factor (VEGF) is known as a vascular permeability factor and a potent mitogen for vascular endothelial cells. In the present study, we investigated whether retinoic acid induces VEGF release in aortic smooth muscle A10 cells and if so, the mechanism of VEGF release. Retinoic acid stimulated VEGF release dose-dependently over the range 0.1 nM-0.1 microM. The retinoic acid-stimulated VEGF release was significantly reduced by actinomycin D. Retinoic acid induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase but not p38 MAP kinase or stress-activated protein kinase/c-Jun N-terminal kinase among the MAP kinase superfamily. This effect of retinoic acid was dose-dependent (30 nM-5 microM) and the maximum effect was observed at 0.3 microM. The retinoic acid-stimulated release of VEGF was significantly reduced by PD98059 and U0126, specific MEK inhibitors, which attenuated the retinoic acid-induced phosphorylation of p44/p42 MAP kinase. These results strongly suggest that retinoic acid stimulates the release of VEGF in a p44/p42 MAP kinase-dependent manner in aortic smooth muscle cells.