Effects of Ca2+ channel antagonists and benzodiazepine receptor ligands in normal and skinned rat urinary bladder.

The effects of Ca2+ channel antagonists and benzodiazepine receptor ligands against concentration-dependent contractions of rat urinary bladder induced by CaCl2 (0.1-50 mM, in K(+)-depolarized tissues), KCl (1-100 mM) and acetylcholine (0.1 microM to 1 mM) were studied. Nifedipine (0.001-0.1 microM), verapamil (0.01-1 microM), diltiazem (0.01-1 microM), cinnarizine (1-100 microM), and trifluoperazine (1-100 microM) each produced a concentration-related inhibition of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (25 mM)-induced contraction of depolarized bladder, was nifedipine (0.01 microM) > diltiazem (0.36 microM) approximately verapamil (0.41 microM) > or = cinnarizine (2.57 microM) > trifluoperazine (17.4 microM). These antagonists depressed KCl-induced contractions with an effectiveness and potency similar to that displayed against CaCl2-induced contractions. Nifedipine, verapamil, and diltiazem but not cinnarizine and trifluoperazine had a preferential inhibitory effect on the contractions elicited by KCl when compared to those elicited by acetylcholine. Ro 5-4864, diazepam, midazolam and the non-benzodiazepine PK 11195, each at 1-100 microM, depressed CaCl2- and KCl-induced contractions (IC50 values in the micromolar range). Benzodiazepines and PK 11195, all at 100 microM, markedly depressed acetylcholine-induced contractions. Flumazenil was scarcely effective. Cinnarizine (100 microM) and trifluoperazine (100 microM), but not the other Ca2+ channel antagonists and benzodiazepine receptor ligands tested, depressed Ca2+ (20 microM)-evoked contractions of skinned bladder. It is concluded that the action of nifedipine, verapamil, and diltiazem is restricted to the plasmalemma whereas cinnarizine and trifluoperazine also act on the intracellular contractile apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of midazolam on the delivery and consumption of myocardial oxygen in the postoperative period of children undergoing heart surgery]. / Efectos del midazolam sobre el aporte y demanda de oxígeno miocárdico en el postoperatorio de niños intervenidos de cirugía cardíaca.

INTRODUCTION: The aim of this study was to evaluate the effect of midazolam on the variables which determine myocardial oxygen delivery and consumption relationship (endocardiac viability index) in children undergoing cardiac surgery under extracorporal circulation. METHODS: The study was carried out in 15 children to whom a doses of midazolam of 0.2 mg/kg was given in immediate postoperative period upon hemodynamic stabilization. The determinations were performed prior to administration of the drug, at 5, 15, and 30 minutes thereafter. The variables analyzed were mean systemic blood pressure, mean diastolic pressure in aorta, mean pressure in the left auriculum, diastolic-systolic time relation, arterial blood O2 content and index of endocardiac viability. RESULTS: The following variables were modified with respect to the basal contributing to an improvement in the endocardiac viability index. Mean aortic diastolic pressure decreased 10.05% at 5 min and 6.17% at 15 min (p < 0.05, p < 0.005); mean systemic arterial pressure decreased 10.64% at 5 min and 6.9% at 15 min (p < 0.05, p < 0.005); the mean pressure in the left auriculum decreased 6.28% at 5 and 8.32% at 15 min (p < 0.05); the diastolic-systolic time relation increased 24.04% at 5 min (p < 0.05, p < 0.005). The index of delivery and consumption of endocardiac oxygen increased 23.4% at 5 min (p < 0.05). CONCLUSIONS: The intravenous administration of midazolam to children at doses of 0.2 mg/kg during the postoperative period of cardiac surgery produced an improvement in the delivery and consumption of oxygen to endocardium at 5 minutes of its administration.

[Application of continuous positive pressure to the uppermost lung in patients ventilated through a single lung]. / Aplicación de presión positiva continua al pulmón proclive en pacientes ventilados a un solo pulmón.

We have studied the oxygenation process in a series of 20 patients who underwent thoracic surgery and were ventilated through a single lung. There were 19 men and one woman with a mean age (+/- SD) of 63 +/- 10.5 years, a mean height of 166 +/- 37.9 cm and a mean weight of 67 +/- 14.1 kg. Premedication and anesthesia were comparable among all patients. Endotracheal intubation was performed with a double lumen Robersthaw cannula. After anesthetic induction the radial and pulmonary arteries were catheterized to obtain samples for gasometric investigation in arterial and venous mixed blood before and after exclusion of one lung with continuous positive pressure (CPAP). Gasometric analysis was also performed during the immediate postoperative period. All patients were ventilated with 100% oxygen concentration 20 min before blood sampling in order to remove the alveolar nitrogen. During single lung ventilation and during application of CPAP (5 cm H20) to the upright sided lung we observed a 50% increase in arterial p02 (Pa02) (p less than 0.001) without any change in mean alveolar p02 (PA02). There was also a 17% decrease in alveolo-arterial oxygen difference (D[A-a]02) (p less than 0.001) and a 16.6% reduction in the intrapulmonary shunt (Qs/Qt) (p less than 0.001). Improvement of oxygenation was attributed to a beneficial effect of CPAP applied to the upright sided lung while intermittent positive pressure was maintained in the recumbent lung.

[Prevalence of HIV antibody carriers in patients assisted in the recovery room]. / Prevalencia de portadores de anticuerpos VIH en pacientes asistidos en reanimación.

A study has been performed on 200 patients at the Recovery Department of our hospital during 1987. This study was carried out in order to determine patients with human immunodeficiency virus (HIV) antibody. This group was randomized and consisted of 154 men and 46 women, with an average age of 35.6 +/- 3.9, a total weight of 68 +/- 6 kg and a height of 1.69 +/- 0.2 m. The day entered at the Recovery Department we assessed the following parameters: a) addiction to drugs by parenteral way; b) bleeding; c) invasive procedures; d) etiology, and e) blood samples were drawn for plasma antibody to HIV. We detected five patients (2.5%) with antibody anti-HIV and all of these patients were male and they were aged in 20-39 years old. We noticed a close relation between addiction to drugs and HIV (p less than 0.001), nevertheless no relation has been found between invasive procedures, bleeding, etiology and antibody to HIV. We conclude that the number of patients that we detected with antibody from the HIV is similar to those found by other studies that has been carried out in emergency situation, but greater than those found in the screening of the general population.

Does discontinuation of desflurane at the time of neostigmine administration speed recovery from cisatracurium block compared to that with a propofol-based technique?

BACKGROUND: Volatile anaesthetics are known to influence the effect of neostigmine as an antagonist of neuromuscular block. The aim of the present study was to investigate whether discontinuation of desflurane at the time of neostigmine administration shortens reversal time from cisatracurium block, compared to that with a propofol-based anaesthesia. METHODS: Ten volunteers were studied twice. For one study, anaesthesia was induced with alfentanil and propofol and maintained with nitrous oxide 70% and propofol 150 microg. kg-1. min-1. For the other study, experimental conditions were replicated except that desflurane 6% was administered and the dose of propofol was only 50 microg. kg-1. min-1. The evoked mechanical response of the adductor pollicis to train-of-four (TOF) stimulation was recorded. Neuromuscular block was induced with cisatracurium 0.2 mg. kg-1. When the magnitude of the first TOF response (T1) had recovered to 10%, the block was antagonized with neostigmine 70 microg. kg-1. At this time, propofol was decreased to 50 microg. kg-1. min-1, or the desflurane was discontinued. RESULTS: There were no significant differences between the two techniques of anaesthesia in the rate of neostigmine-induced recovery of the TOF ratio. The times (mean+/-SD) to achieve TOF ratios of 0.7, 0.8, and 0.9 were (propofol first, desflurane second) 6.1+/-2.2 and 6.5+/-1.6 min; 10.4+/-4.2 and 9.6+/-2.7 min; 17.1+/-6.9 and 21.0+/-13.0 min, respectively. CONCLUSION: Discontinuing desflurane does not speed neostigmine-induced recovery from cisatracurium neuromuscular block, when compared to that during propofol-based anaesthesia.

Effect of renal failure and cirrhosis on the pharmacokinetics and neuromuscular effects of rapacuronium administered by bolus followed by infusion.

BACKGROUND: Recent trials indicate that rapacuronium's pharmacokinetic characteristics are influenced by both renal failure and cirrhosis but the time course of a single bolus dose of 1.5 mg/kg is affected minimally. The authors reassessed these pharmacokinetic findings and examined the time course of the same bolus dose followed by a 30-min infusion. METHODS: During nitrous oxide-isoflurane anesthesia, patients with normal renal and hepatic function (n = 25), those with renal failure (n = 28), and those with cirrhosis (n = 6) received a bolus dose of rapacuronium (1.5 mg/kg) followed by a 30-min infusion adjusted to maintain 90-95% twitch depression. At 25% recovery, neostigmine was administered. Blood was sampled until 8 h after the infusion to determine concentrations of rapacuronium and its active metabolite ORG9488. Rapacuronium's pharmacokinetic parameters were determined using mixed-effects modeling. RESULTS: Onset and facilitated recovery of twitch depression were similar in the three groups. Patients with renal failure required 22% less rapacuronium to maintain target twitch depression during the infusion. Rapacuronium's plasma clearance was 24% smaller in renal failure and decreased 0.5%/yr of age; rapid distribution clearance was 51% smaller in men than in women. After the infusion, ORG9488 concentrations decreased markedly more slowly in patients with renal failure. Cirrhosis did not alter the pharmacokinetics of rapacuronium. CONCLUSION: Rapacuronium's plasma clearance and infusion requirement were decreased by renal failure. By dosing to maintain target twitch depression, recovery was not prolonged. Cirrhosis does not affect the pharmacokinetics or neuromuscular effects of rapacuronium. Persistence of ORG9488 in patients with renal failure might prolong recovery after rapacuronium if target twitch depression is not maintained or with administration of rapacuronium for more than 30 min.

Parada cardíaca durante la anestesia espinal en la cesárea / Cardia arrest during a cesarean section with spinal anesthesia

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