Seguridad y eficiencia de sedación balanceada con propofol y remifentanil en endoscopia digestiva alta diagnóstica. Una experiencia exitosa / A Successful Experience: Safety and Efficiency of Balanced Sedation with Propofol and Remifentanil in Diagnostic Endoscopy

Resumen La sedación es una técnica anestésica de amplio uso en los procedimientos endoscópicos digestivos actuales dado su claro beneficio en la tolerancia y comodidad para el paciente y el endoscopista. El medicamento de mayor uso en la actualidad para utilizarse como monosedación es el propofol, pero los esquemas balanceados utilizando más de un medicamento ahora son ampliamente usados en endoscopia diagnóstica o terapéutica. La sedación balanceada utilizando propofol y remifentanilo permite la potenciación sinérgica de un sedante con un opioide de ultracorta acción, lo que a su vez favorece la disminución respectiva de cada dosis. Se presenta una serie de 1148 pacientes llevados a endoscopia digestiva alta diagnóstica con dosis promedio de remifentanilo de 0,9 µg/kg de peso y de propofol de 0,47 mg/kg de peso, sin eventos adversos graves, con excelente satisfacción para el endoscopista y con muy bajo costo de la dosis por medicamento, con lo que se infiere que es un esquema seguro y eficiente.

Abstract Sedation is an anesthetic technique that is widely used in current digestive endoscopic procedures because of its clear benefits for patients' tolerance and comfort and for the endoscopist. Propofol is the most commonly used drug in monosedation, but balanced regimens using more than one drug are now widely used in diagnostic and therapeutic endoscopy. Balanced sedation using Propofol and Remifentanil allows synergistic potentiation of a sedative with an ultra-short acting opioid which in turn favors decreases of each dose. This is a series of 1,148 patients who underwent diagnostic endoscopy under balanced sedation with average Remifentanil doses of 0.9 mcg/kg of body weight and average Propofol doses of 0.47 mg/kg of body weight. There were no serious adverse events, endoscopists were highly satisfied with the procedures, and costs per drug dose were very low. This is clearly a safe and efficient scheme.

Treatment of symptomatic HyperLp(a)lipoproteinemia with LDL-apheresis: a multicentre study.

LDL-apheresis (LDLa) efficacy in the treatment of symptomatic HyperLp(a)lipoproteinemia -HyperLp(a)- has been studied in a multicentre trial. After 3.1+/-2.7 years of weekly and biweekly treatment, the data from 19 patients (males:12; females:7; aged 53.8+/-9.3 years; mean body mass index: 24.6+/-2.3 Kg/m²) were evaluated. Data were collected using the same questionnaire shared by 5 participating centres. A total of 2331 procedures were performed. A mean of 3593.7+/-800.3 ml of plasma or 8115.3+/-2150.1 ml of blood, depending upon the technique used (H.E.L.P., D.A.LI., Dextransulphate, Lipocollect 200), was regularly treated on average every 10.1+/-2.6 days. Baseline mean Lp(a) levels were 172.3+/-153.8 mg/dL. The mean pre-/post-apheresis Lp(a) levels decreased from 124.5+/-107.2 mg/dL (p<0.001 vs baseline) to 34.2+/-40.6 mg/dL (p<0.001 vs pre-). Baseline mean LDL-cholesterol (LDLC) levels were 152.3+/-74.6 mg/dL. The mean pre-/post-apheresis LDLC levels decreased from 130.4+/-61.1 mg/dL (p<0.004 vs baseline) to 41.2+/-25.1 mg/dL (p<0.001 vs pre-). The hypolipidemic drugs given to the patients during LDLa were: ezetimibe+simvastatin, atorvastatin, rosuvastatin, pravastatin, acipimox, and omega-3 fatty acids. 58% of the patients had arterial hypertension. Cigarette smokers were 5.3%. Alcohol intake was present in 21%. 52.6% were physically active. Patients with coronary artery disease (CAD) submitted to coronary catheterization before LDLa were 95%. In 5.5% (#1) CAD recurred despite treatment with LDLa. 79% were submitted to coronary revascularization before LDLa. CAD was: monovasal in 8 patients (42.1%), bivasal in 5 (26.4%), trivasal in 4 (21%), plurivasal in 2 (10.5%). In 94.5% of the sample the lesions were stable (< 0% deviation) over 3.1+/-2.7 years. 37% had both CAD and extra-coronary artery disease. This multicentre study confirmed that long-term treatment with LDLa was at least able to stabilize CAD in the majority of the individuals with symptomatic HyperLp(a).

Trans-synaptic modulation of striatal ACh release in vivo by the parafascicular thalamic nucleus.

Electrical stimulation of the parafascicular but not the ventrolateral or dorsomedial thalamic nucleus (ten 0.5 ms, 10 V pulses, 140 microA) of freely moving rats induced a frequency-dependent (2.5, 5, 10 and 20 Hz) increase in the extracellular acetylcholine (ACh) content of the dorsal striatum, assessed by trans-striatal microdialysis. The time-dependent effect of 10 Hz stimulation was studied. The peak increase, 39% above baseline, was attained during 4 min of stimulation. This was blocked by coperfusion with 5 microM tetrodotoxin, indicating that the release we measured represents a physiological process. The facilitatory effect of parafascicular nucleus stimulation does not appear to be associated with indirect action through the cerebral frontal cortex because acute lesion of the excitatory corticostriatal afferents, which by itself reduced basal ACh release by 40%, did not modify the effect of 10 Hz stimulation. The possible involvement of the fasciculus retroflexus in the facilitation of ACh release was also ruled out. The non-competitive NMDA-type receptor antagonist MK-801, applied by reversed dialysis (30 microM) or systemically injected (0.2 mg/kg), significantly reduced the basal ACh output and prevented the tetanus-evoked increase in ACh release. The results provide in vivo evidence that the activity of the cholinergic neurons in the dorsal striatum is trans-synaptically modulated by parafascicular nucleus excitatory afferents through activation of the NMDA subtype of glutamate receptors that is probably located in the striatum.

Role of vesicular dopamine in the in vivo stimulation of striatal dopamine transmission by amphetamine: evidence from microdialysis and Fos immunohistochemistry.

The role of vesicular and newly synthesized dopamine in the action of amphetamine was investigated by studying the effect of reserpine and alpha-methyl-p-tyrosine pretreatment on amphetamine-induced changes in extracellular dopamine and acetylcholine, estimated by brain microdialysis, and on c-fos expression, estimated by quantitative immunohistochemistry of the Fos antigene, in the dorsal caudate-putamen of rats. Blockade of dopamine synthesis by alpha-methyl-p-tyrosine pretreatment (1 or 2 h) only partially prevented the increase in extracellular dopamine concentrations elicited by 0.5 and 2 mg/kg s.c. of amphetamine. Inactivation of vesicular amine uptake by reserpine pretreatment (3 h) reduced the increase in extracellular dopamine by 2 mg/kg but not by 0.5 mg/kg of amphetamine. Combined pretreatment with reserpine (3 h) and alpha-methyl-p-tyrosine (1 h) drastically reduced the increase in extracellular dopamine by both doses of amphetamine (0.5 and 2 mg/kg s.c.). alpha-Methyl-p-tyrosine pretreatment reduced c-fos expression stimulated by amphetamine (2 mg/kg) in the dorsomedial and dorsolateral caudate-putamen while reserpine pretreatment reduced it only in the dorsolateral caudate-putamen. Amphetamine (2 mg/kg s.c.) stimulated acetylcholine release but this effect was not modified by reserpine or alpha-methyl-p-tyrosine pretreatment. The results indicate that blockade of dopamine synthesis, by itself, is insufficient to prevent the stimulation of dopamine transmission by amphetamine and, conversely, that inactivation of vesicular dopamine significantly reduces amphetamine effects at pre- and postsynaptic levels. Therefore, vesicular dopamine appears to contribute to the stimulation of dopamine transmission elicited by amphetamine in the dorsal caudate-putamen.

Impulse flow dependency of galanin release in vivo in the rat ventral hippocampus.

Using microdialysis and a sensitive RIA, we have studied the in vivo release of the neuropeptide galanin (GAL) from the ventral hippocampus of freely moving rats. The spontaneous outflow of GAL-like immunoreactivity (GAL-LI) (1.8 +/- 0.3 fmol per ml per 20 min) was dependent on the presence of extracellular Ca2+ and was inhibited by tetrodotoxin. Evoked release induced by infusion of KCl (60 mM) or veratridine (148 microM) was also Ca(2+)-dependent and sensitive to tetrodotoxin. Electrical stimulation of the ventral limb of the diagonal band nuclei induced a frequency-dependent (50-200 Hz) and tetrodotoxin-sensitive overflow of GAL-LI in the hippocampus. In vitro GAL-LI release (1.0 +/- 0.02 fmol per ml per 5 min), studied in slices of rat ventral hippocampus, was also Ca(2+)-dependent and was increased in a concentration-dependent manner by KCl depolarization. This study demonstrates the release of the neuropeptide GAL in the rat central nervous system. The in vivo release is related to the activity of the cholinergic GAL-LI-containing cells in the septal diagonal band nuclei. The results are discussed in relation to the coexistence of GAL and acetylcholine within the septal/diagonal band complex.

Serotonergic facilitation of acetylcholine release in vivo from rat dorsal hippocampus via serotonin 5-HT3 receptors.

The serotonin (5-HT) releaser d-fenfluramine and its active metabolite d-norfenfluramine, or the 5-HT-uptake inhibitor citalopram, by increasing synaptic 5-HT availability, facilitated in vivo release of acetylcholine (ACh) from dorsal hippocampi of freely moving rats as determined by the microdialysis technique. The effects of d-norfenfluramine (7.5 mg/kg i.p.) and citalopram (10 microM, applied by reverse dialysis) were prevented by a 14-day chemical lesion of the raphe nuclei, suggesting mediation by the 5-HT system in the cholinergic action of the drugs. The increase in extracellular ACh content induced by d-norfenfluramine (5 mg/kg i.p.) was antagonized by the 5-HT3 receptor antagonists tropisetron (0.5 mg/kg i.p.) and DAU 6215 (60 micrograms/kg i.p.), but not by the mixed 5-HT1 and 5-HT2 receptor antagonist metergoline (2 mg/kg s.c.). In accordance with an involvement of the 5-HT3 receptor in the ACh facilitation induced by d-norfenfluramine is the finding that the selective 5-HT3 receptor agonist 2-methylserotonin (250 micrograms i.c.v., or 10 microM applied by reverse dialysis) raised ACh release. The effect of the intracerebroventricular drug was prevented by the 5-HT3 antagonists DAU 6215 (60 micrograms/kg i.p.) and ondansetron (60 micrograms/kg s.c.). These antagonists by themselves did not modify the basal ACh release, indicating that 5-HT does not tonically activate the 5-HT3 receptors involved. In conclusion, the overall regulatory control exerted by 5-HT in vivo is to facilitate hippocampal ACh release. This is mediated by 5-HT3 receptors probably located in the dorsal hippocampi.

5-HT4 receptor stimulation facilitates acetylcholine release in rat frontal cortex.

The effect of the serotonergic 5-HT4 receptor agonists BIMU 1 and BIMU 8 on in vivo acetylcholine (ACh) release in brain hemispheric regions of freely moving rats was investigated using the microdialysis technique. Both agonists, applied intracerebroventricularly, facilitated the release of ACh selectively in the frontal cortex and were ineffective in the striatum or dorsal hippocampus. The facilitatory effect of BIMU 1 in frontal cortex was prevented by the selective 5-HT4 receptor antagonists GR 125487 and GR 113808 which by themselves did not alter basal release. the results provide the first evidence that serotonin facilitates ACh release in frontal cortex through stimulation of 5-HT4 receptors which are not tonically activated. 5-HT4 receptor agonists might thus offer a novel means of boosting central cholinergic function to overcome the cholinergic deficit in memory disorders.

Neuroleptics increase striatal acetylcholine release by a sequential D-1 and D-2 receptor mechanism.

In normal striata, pre-treatment with the D-1 antagonist SCH 23390 (250 and 25 micrograms kg-1, s.c.) completely and lastingly prevented the D-2 antagonist remoxipride (REM) from increasing acetylcholine (ACh) release; post-treatment did not affect REM action. In alpha-methyl-p-tyrosine (alpha-MpT) dopamine (DA)-depleted striata, however, pretreatment with SCH 23390 resulted in a transient impairment of REM induced stimulation of ACh release but post-treatment still had no effect. Two different mechanisms therefore seem to be involved in D-2 antagonist-induced stimulation of ACh release; the antagonists indirectly activate a D-1 receptor-mediated facilitatory mechanism regulating cholinergic function, and directly block a D-2 receptor-mediated inhibitory one. In normal rats, in an early phase after D-2 antagonist administration, only the first mechanism is operative; in a later phase, both mechanisms cooperate in the stimulation of ACh release. When DA release is impaired by alpha-MpT, the D-2 inhibitory receptor mechanism becomes more important than the D-1 facilitatory one in controlling ACh release.

Stimulation of dopamine transmission in the dorsal caudate nucleus by pargyline as demonstrated by dopamine and acetylcholine microdialysis and Fos immunohistochemistry.

The effect of pargyline on dopamine neurotransmission was investigated by trans-striatal microdialysis combined with Fos immunohistochemistry. Pargyline, 75 mg/kg i.p., increased dopamine and acetylcholine output while drastically decreased dopamine deaminated metabolites. Administration of pargyline resulted in the appearance of Fos-positive nuclei distributed along a gradient around the dialysis probe. Pretreatment with the D1 antagonist SCH 23390 potentiated the effect of pargyline on dopamine output while preventing that on acetylcholine output and on Fos formation. Similarly, lack of calcium in the perfusion medium abolished the effect of pargyline on dopamine and acetylcholine output and on Fos formation. In rats not implanted with dialysis probes pargyline administration resulted in only rare Fos-positive nuclei in the dorsal caudate. The present study indicates that pargyline stimulates dopamine transmission in the dorsal caudate in the area around the dialysis probe but not distant from the fibre or in unimplanted rats. This effect appears to reflect an interaction between the drug-induced changes and those locally elicited by the probe.

Endogenous dopamine facilitates striatal in vivo acetylcholine release by acting on D1 receptors localized in the striatum.

Intrastriatal application of the D1 antagonist SCH 23390 by two procedures, reverse dialysis (20 microM) and local injection (0.45 nmol per striatum), elicited a reduction in acetylcholine (ACh) release superimposable on that induced by systemic administration. The novel selective D1 antagonist SCH 39166 produced a similar decreasing effect on striatal ACh release on local injection (0.45 nmol per striatum). On the other hand, local application of SCH 23390 into the frontal cortices (0.45 nmol per side) failed to alter striatal ACh overflow, indicating that the drug does not diffuse out of its injection site to any significant extent. The dopamine release inducer d-amphetamine (2 mg/kg s.c.) and the dopamine uptake inhibitor cocaine raised ACh release like the D1 agonists. These effects were completely blocked by 10 microM SCH 23390 applied by reverse dialysis. The results suggest that D1 receptors regulating ACh release are located in the striatum.

Cyclazocine and norepinephrine uptake, metabolism, and turnover in the rat brain.

The effects of cyclazocine, a narcotic agonist/antagonist, on the uptake, metabolism, and turnover of norepinephrine in rat brains were studied. Cyclazocine significantly depressed the accumulation of intracisternally administered [3H]norepinephrine and the formation of 3,4-[3H]dihydroxymandelic acid but did not alter the formation of [3H]-normetanephrine. Comparatively, imipramine reduced the uptake of [3H]norepinephrine, decreased the formation of 3,4-[3H]dihydroxymandelic acid, and increased the formation of [3H]normetanephrine. Moreover, cyclazocine increased the formation of endogenous 3-methoxy-4-hydroxyphenylethylene glycol and produced a fall in endogenous norepinephrine. It is suggested that cyclazocine reduces the accumulation of [3H]norepinephrine, decreases endogenous norepinephrine levels, and increases the formation of 3-methoxy-4-hydroxyphenylethylene glycol by interacting with brain adrenergic nerves, presumably by inhibiting neuronal uptake and facilitating norepinephrine turnover.

Thymopentin treatment of selective IgA deficiency.

Thymic hormones have been shown to modulate immunoglobulin production in a number of experiments and it is generally agreed that this action is mediated by modulation of helper and/or suppressor T cell activities. The possibility of upregulating the immunoglobulins is of particular relevance in patients with hypogammaglobulinemias and this paper reports on the results of thymopentin treatment in 9 patients with selective IgA deficiency. Two out of 4 patients responded positively in an open-label trial; in one the serum IgA values remained stable up to 8 weeks after discontinuation of treatment whereas there was a rapid fall in the other. Both responders had consistently normal T4/T8 ratios during the treatment, whereas the nonresponders revealed high ratios with large fluctuations of the T4/T8 ratio. In a subsequent (still ongoing) double-blind trial in 5 patients (3 thymopentin, 2 placebo) no significant change of serum or secretory IgA levels has been observed. Taken together, the data suggest that the tested dose regimen of thymopentin (i.e. daily i.m. injections of 1 mg/kg for 2 weeks, then same dose 3 time weekly for 10 weeks) may only work in a subset of patients with selective IgA deficiency. In the present study we did not attempt to distinguish to which of the three known subgroups the 9 patients belonged, nor did we try alternative dose regimens of thymopentin.

Interaction of cyclazocine and the sympathetic nervous system.

Cyclazocine, a benzomorphan derivative narcotic agonist-antagonist, reduced the uptake of tritiated norepinephrine and reduced the recovery of [3H]3,4-dihydroxymandelic acid, but did not significantly alter the recovery of [3H]normetanephrine in the rat heart in vivo. Cyclazocine also reduced endogenous levels of norepinephrine in the rat heart. Comparatively, desipramine reduced the uptake of [3H]norepinephrine, the recovery of [3H]3,4-dihydroxymandelic acid, and the recovery of [3H]normetanephrine in the rat heart in vivo. Further, cyclazocine added to the perfusion medium or administered systemically reduced the uptake of radiolabeled norepinephrine by the isolated rat heart. The cyclazocine-induced decrease in the accumulation of [3H]norepinephrine in the rat heart in vivo and in vitro presumably is due to an alteration of sympathetic function through the inhibition of neuronal uptake. It is further suggested that cyclazocine has other actions on the sympathetic nervous system, such as promoting neurotransmitter release.

Effect of pentazocine on pressor responses of epinephrine and levarterenol.

In rats anesthetized with pentobarbital, pentazocine potentiated the pressor response of two exogenous amines, epinephrine and levarterenol. Although the mechanism for the pentazocine-induced potentiation of the pressor amines has not been proven, it is speculated that pentazocine may increase the blood pressure response of certain amines by interacting with the sympathetic nervous system.