Background and objective: The aim was to examine the course of intraocular pressure after relaxation with different doses of cisatracurium.

Methods: The investigation was carried out as a prospective, randomized double-blind study in a crossover design in 30 postoperative patients with stable haemodynamic and respiratory function (ASA I and II). To exclude any disrupting factors, patients remained intubated and continuously sedated. Twenty patients received an intubation dose (2 × ED95) of cisatracurium (0.1 mg kg−1) compared with atracurium (0.5 mg kg−1). In a second series, 10 patients were given an effective dose, ED95 (0.05 mg kg−1), and a repeat dose (0.02 mg kg−1) of cisatracurium. The intraocular pressure was determined before (T0) as well as 1 (T1), 5 (T5), 10 (T10), 15 (T15), 20 (T20) and 45 (T45) min after bolus administration.

Results: Intraocular pressure decreased after an intubation dose of either cisatracurium or atracurium, and reached a minimum after 10 min (6.7 ± 2.2 and 7.9 ± 2.1 mmHg, respectively). There was no significant difference between either muscle relaxant (P = 0.27). When lower doses of cisatracurium (0.05 and 0.02 mg kg−1) were applied, the intraocular pressure also decreased, albeit to a lesser extent and with a delayed onset (8.4 ± 1.9 mmHg after 10 min, 9.9 ± 3.4 mmHg after 15 min). There was no significant difference between dosages (P = 0.44).

Conclusions: Cisatracurium is a useful drug in patients when a decrease of intraocular pressure is wanted and where muscle relaxation is necessary and acceptable.

Laudanosine is a metabolite of the neuromuscular-blocking drugs atracurium and cisatracurium with potentially toxic systemic effects. It crosses the blood-brain barrier and may cause excitement and seizure activity. Its interest in recent years has increased because of the recognized interaction with γ-aminobutyric acid, opioid and nicotinic acetylcholine receptors. It has been shown to produce analgesia in animals. In the cardiovascular system, high plasma concentrations produce hypotension and bradycardia. In hepatic failure, its elimination halflife is prolonged but only moderate accumulation occurs in adults, whereas in infants and children plasma concentration are greater. In patients undergoing liver transplantation, laudanosine concentrations are increased during preanhepatic, anhepatic and postanhepatic stages. Patients with renal failure have higher plasma concentrations and a longer mean elimination half-life. In pregnancy, laudanosine crosses the placental barrier. The mean transplacental transfer is 14% of maternal blood concentrations. Except for prolonged administration of atracurium in intensive care units, laudanosine accumulation and related toxicity seem unlikely to be achieved in clinical practice. When cisatracurium is used, plasma concentrations of laudanosine are lower. Further studies are needed, especially around the interactions with γ-aminobutyric acid, opioid and nicotinic acetylcholine receptors.

Background and objective: The addition of alfentanil or atracurium to lidocaine solution for intravenous regional anaesthesia of the arm may have advantages with respect to improved muscle relaxation and better analgesia. The study investigates these possibilities.

Methods: We investigated 33 patients. Plain lidocaine solution was administered to Group 1 (n = 11). Alfentanil (0.5 mg) and atracurium (3 mg) were added to the lidocaine solution in Groups 2 (n = 11) and 3 (n = 11), respectively. The onset of sensory and motor block, intra- and postoperative pain scores, and the duration of postoperative analgesia were evaluated.

Results: There was a significant difference in the speed of the onset of sensory block in the hand, but not at the tourniquet site. The onset of the motor block, intra- and postoperative pain scores, and the duration of postoperative analgesia were similar in all groups.

Conclusions: No clinical benefits of adding alfentanil or atracurium to lidocaine solution for intravenous regional anaesthesia of the arm could be shown.

It has been estimated that more than 60% of all paediatric surgery is performed on a day case basis. The benefits of this type of surgery in children include reduced costs, avoidance of the stress of hospitalization and less disruption to family life. The growth of day surgery in children has been facilitated by the development of non-depolarizing neuromuscular blocking agents characterized by short and intermediate duration of action and fewer side-effects. The more rapid onset and shorter duration of action of non-depolarizing neuromuscular blocking agents in children should facilitate the use of these agents in place of succinylcholine for day case procedures.

Background and objective Inflammatory liver dysfunction in rats leads to a prolonged vecuronium-induced neuromuscular blockade due to insufficient metabolism. A coexisting resistance against the drug partly counteracts this prolongation. The present study investigates the pharmacodynamics of atracurium whose metabolism does not depend on liver function.

Methods Male Sprague–Dawley rats (n = 14; 290 ± 30 g) were randomly allocated to either a group in which liver inflammation was induced by intravenous injection of 60 mg kg−1 heat-killed Corynebacterium parvum or to a control group. On day 5 after injection, liver function was assessed using the aminopyrine breath test. Under propofol anaesthesia, duration of action of atracurium (4.8 mg kg−1) was measured by evoked mechanomyography (stimulation of the sciatic nerve; contraction of the gastrocnemius muscle). Nitric oxide concentrations, as variables for the severity of the inflammation, were assessed by measurement of nitrite/nitrate plasma concentrations.

Results In C. parvum-injected rats, nitrite/nitrate plasma concentrations were increased (972 ± 597 vs. 25 ± 7 μmol L−1), the aminopyrine turnover was depressed (1.7 ± 0.4% vs. 3.5 ± 0.5%), and the atracurium-induced neuromuscular blockade was shortened (372 ± 128 s vs. 1081 ± 234 s).

Conclusions A systemic inflammatory response syndrome with liver dysfunction results in decreased sensitivity to atracurium. Further investigations are needed regarding a possible up-regulation of acetylcholine receptors or an increased protein binding of atracurium during sepsis to clarify reasons behind this phenomenon.

The aim of this study was to elucidate the influence of four neuromuscular blocking substances on coronary vascular tone using the model of isolated porcine coronary artery segments. We studied the effects of four muscle relaxants, atracurium, pancuronium, rocuronium, and vecuronium (0.1, 1, and 10 μg mL−1 each), on the contractile response to three vasoconstrictors: acetylcholine, histamine, and serotonin. None of the neuromuscular blocking agents under investigation exerted a significant influence on the vasoconstricting effects of these mediators except for pancuronium, which dose-dependently attenuated acetylcholine-mediated contractions (−10.8% attenuation for 10 μg mL−1 pancuronium, P < 0.05). There was no difference between vessels with intact endothelium and denuded preparations. It is concluded that high-dose pancuronium exerts an antimuscarinic effect in vascular smooth muscle. The other neuromuscular agents studied do not alter vascular reactivity of isolated porcine coronary arteries.

A 43-year-old male received intravenous propofol, atracurium and gentamicin and experienced cardiovascular collapse with the features of an acute drug reaction. Prolonged cardiopulmonary resuscitation with fluids and large amounts of adrenaline and nor-adrenaline led to full recovery without neurological deficit. No biochemical abnormality was detected.

In order to compare the neuromuscular effects following rocuronium 0.6 mg kg−1 and atracurium 0.5 mg kg−1 30 children aged from 18 to 67 months were studied under the same anaesthetic conditions. After induction of anaesthesia with etomidate and fentanyl, neuromuscular blockade was monitored by recording the electromyographic response of the adductor pollicis muscle to a supramaximal train-of-four (TOF) stimulation of the ulnar nerve at 2 Hz for 2 s at 20-s intervals. Intubation was performed when more than 90% muscle relaxation was achieved, thereafter anaesthesia was maintained with 70% nitrous oxide in oxygen and isoflurane 0.5% end-tidal. Mean onset of action was significantly faster following rocuronium (86±44.9 s) (mean±SD) compared with atracurium (126.3±61.0 s). Clinical duration with rocuronium was 22.8±5.31 min and thus significantly shorter than that of atracurium, which was 31.5±6.01 min. A statistically significant difference between rocuronium and atracurium also had been found for recovery of T1 to 50%, 75% and 90% as well as for the time taken to a TOF ratio of 70%. The recovery index for rocuronium and atracurium was not significantly different with 9.2±3.43 min and 10.9±2.65 min, respectively. Thus, rocuronium may be more advantageous than atracurium for short-lasting surgical procedures in young children.

Atracurium causes a decrease in systemic vascular resistance (SVR) and mean arterial blood pressure (MAP) which has been ascribed to histamine release. However, histamine receptor blockade does not prevent these decreases completely. The hypotensive side effects of atracurium may not only be caused by histamine. In this study we examined the vasoactive effects of atracurium with and without histamine receptor blockade in an isolated femoral artery preparation of the rabbit. We also investigated whether vasodilatation caused by atracurium depends on the presence of endothelial cells. Tyrode perfused, rabbit femoral arteries were constricted with noradrenaline (NA) to ±70% of their passive diameter. Endothelial function was checked with acetylcholine (ACh). The vessels were divided into two groups. In both groups the responses to histamine (1.0−10−6m) and atracurium (3.2−10−5m) were determined. In group one (n = 5), the histamine and atracurium responses were repeated during histamine receptor blockade. In group two (n = 5), the diameter responses to histamine and atracurium before and after endothelium removal were compared. Also, some vessel segments (n = 5) were histologically prepared and examined for mast cells. The vasodilatory responses to atracurium both with and without histamine receptor blockade were the same. Removal of endothelium caused an increase in the histamine response, while the dilating response to atracurium remained constant. We conclude that in the isolated femoral artery of the rabbit, atracurium induces vasodilatation that is not mediated by histamine release and cannot be prevented with histamine receptor blockade. The mechanism of atracurium induced dilation is independent of the endothelium and is located in the smooth muscle cell.