The use of rocuronium (ORG 9426) in patients with chronic renal failure

The pharmacodynamics of an initial dose of 0.6 mg.kg-1 rocuronium followed by three maintenance doses of 0.15 mg.kg-1 were studied during nitrous oxide/oxygen/isoflurane anaesthesia in patients with normal renal function (n = 12) and chronic renal failure (n = 12). The mean (SD) duration (min) of block after the initial dose was 28.0 (5.5) and 25.6 (11.7) respectively. The mean (SD) duration (min) of the effect of the three maintenance doses was 15.3 (4.0) and 14.2 (7.0); 17.3 (3.2) and 17.4 (8.7); 18.1 (2.8) and 19.1 (10.1) for the normal and renal failure patients respectively. The induced and spontaneous recovery indices were 3.7 (0.7) and 17.1 (6.9) in the normal group compared with 3.9 (0.5) and 19.0 (12.5) in the renal failure group and these values did not differ between the two groups. In this small study rocuronium appears to be suitable for patients with chronic renal failure. There is no evidence of prolonged block even when the drug is given in repeated doses for maintenance.

Evaluation of the time course of action of maintenance doses of rocuronium (ORG 9426) under halothane anaesthesia

The time course of action of rocuronium was compared using three different sizes of maintenance doses after at least three subsequent administrations of the same repeat dose in each patients under halothane anaesthesia. Following endotracheal intubation facilitated with 0.6 mg.kg-1 rocuronium (ORG 9426), muscle relaxation was maintained in three groups each consisting of ten patients, using increments of equal repeat doses of either 75 micrograms.kg-1, 150 micrograms.kg-1 or 225 micrograms.kg-1 equivalent to 1/4, 1/2 and 3/4 of the ED95 of this new compound, respectively. Maintenance doses were administered when the twitch height depression induced by the previous dose returned to 25% of its control value. The clinical duration of the intubating dose averaged 27 +/- 7.5 min (mean +/- s.d.). The time course of action of the various maintenance doses depended on their size, but not on the number of administrations. The durations of repeat doses averaged 8-9 min, 14-16 min and 19-23 min after the low, medium and high maintenance doses, respectively. No overt cumulative effects were observed.

Antagonism of vecuronium by one of its metabolites in vitro

The neuromuscular-blocking agent vecuronium bromide undergoes hydrolysis to three pharmacologically active metabolites (3-desacetyl, 17-desacetyl and 3,17-desacetyl vecuronium) which might modify the neuromuscular-blocking action of their parent compound. In order to elucidate the possible role of the interaction between vecuronium and its metabolites in the complications reported after long-term use of vecuronium in intensive care unit (ICU) patients, the relative potency of vecuronium, 3-desacetyl and 3,17-desacetyl vecuronium was determined in the rat hemidiaphragm in vitro and the mode of interaction of the above-mentioned compounds investigated. Dose-response relationships were established for each substance alone and for combinations of vecuronium with its metabolites. The relative potency at the EDmax50 levels (% maximal effect) were in the order of 1:1.2:27 for vecuronium, the 3-desacetyl derivative and the 3,17-desacetyl derivative, respectively. The mode of interaction characterized by isobolographic and algebraic (functional) analysis showed vecuronium and 3-desacetyl vecuronium to interact in an additive fashion while the combined effect of the parent compound and its 3,17-desacetyl derivative was less than additive, indicating antagonism.

Atrial natriuretic peptide (ANP), aldosterone, angiotensin II and renin in the 'low T3 syndrome' in organ donors

The present prospective study was conducted in order to investigate the effect of an acute decrease in serum T3 levels on ANP, aldosterone, angiotensin II, renin and ADH. All patients showed a pathologic TRH stimulation test prior to organ harvesting. Our patients developed secondary T3 hypothyroidism of different severity dependent on intensive care unit (ICU) stay. T3 values in group 1 (ICU stay > or = 77 h) were smaller than 70 ng/dl, those of group 2 (ICU stay < or = 53 h) were greater than 70 ng/dl. In both groups a severe elevation of plasma renin activity was measured, with almost high-normal values for ANP in group 1 and slightly elevated values in group 2 [not significant (n.s.)]. Results demonstrate that, contrary to patients who are not critically ill, brain-dead patients develop a dissociation of the renin-angiotensin-aldosterone mechanism. No statistical significant difference was found between the groups in serum levels of ADH and aldosterone. This endocrine dissociation, however, seems to have no clinical significance with regard to organ function after transplantation in kidney recipients.

Evaluation of the endotracheal intubating conditions of rocuronium (ORG 9426) and succinylcholine in outpatient surgery

The time-course of action and tracheal intubating conditions of rocuronium and succinylcholine under intravenous anesthesia with propofol, alfentanil, and nitrous oxide were studied in 30 patients undergoing outpatient surgery. The neuromuscular effects of both drugs were quantified by recording the indirectly evoked twitch response of the adductor pollicis muscle after ulnar nerve stimulation (0.1 Hz, 0.2 ms supramaximal stimuli). Patients were given either 0.6 mg/kg rocuronium (n = 20) or 1 mg/kg succinylcholine (n = 10) intravenously. Sixty seconds after the administration of the muscle relaxant, the trachea was intubated and the intubating conditions were scored by a "blinded" assessor. Intubating conditions were not different (P = 0.34) between the rocuronium and succinylcholine groups. The onset and duration of neuromuscular blockade were shorter with succinylcholine than with rocuronium. The depression of the twitch response to 5% of control value occurred in 0.8 +/- 0.1 min with 1 mg/kg succinylcholine and 1.2 +/- 0.5 min with 0.6 mg/kg rocuronium (P less than 0.01). The recovery of the twitch response to 25%, 75%, and 90% of its control value was shorter after succinylcholine (P less than 0.001) and occurred at 8.1 +/- 2.6, 10.3 +/- 3.9, 11.3 +/- 4.6 and 25.3 +/- 5.0, 33.1 +/- 5.9, 36.1 +/- 6.3 min after succinylcholine and rocuronium, respectively. Also the time required for spontaneous recovery from 25% to 75% of the control twitch response was significantly shorter (P less than 0.001) after succinylcholine (2.2 +/- 1.4 min) than after rocuronium (7.8 +/- 2.1 min). It is concluded that in spite of the pharmacodynamic differences between succinylcholine and rocuronium, the intubating conditions after administration of both compounds are similar and develop at the same rate.

High-tension electrical-arc-induced thermal burns caused by railway overhead cables

Eleven patients with high-tension electrical-arc-induced thermal burns due to railway overhead cables were treated at the Bratislava Burn Department during a relatively short period of 18 months. All the injuries occurred by the same mechanism, that is persons climbing on top of railway carriages and approaching the 25,000 V a.c. overhead cables. All the burns were the result of an electrical arc passing externally to the body, with subsequent ignition of the victim's clothes. The cutaneous burns, ranging from 24 to 79 per cent of the BSA, were mostly deep partial to full skin thickness injuries. One patient died on day 5 postburn, the other survived. In spite of high-tension aetiology, no true electrical injuries appear to have occurred and no amputations were necessary. The pathophysiology and possible preventive measures are discussed. It must be stressed that arcing can be induced by an earthed object approaching, but not touching, a cable carrying a high voltage.

Comparison of vecuronium- and atracurium-induced neuromuscular blockade in postpartum and nonpregnant patients

The time-course of action of 0.1 mg/kg vecuronium and 0.5 mg/kg atracurium was investigated in nonpregnant and in postpartum patients within 4 days after delivery. The clinical duration of vecuronium, but not that of atracurium, was significantly prolonged in the latter group (P less than 0.001) and averaged 36 +/- 6 and 37 +/- 4 min for atracurium and 32 +/- 6 and 49 +/- 10 min for vecuronium in nonpregnant and in postpartum patients, respectively (mean +/- SD). In additional in vitro experiments in the rat phrenic nerve-hemidiaphragm preparation no difference could be observed in the neuromuscular blocking effects of vecuronium in postpartum and nonpregnant female rats. It is concluded that pregnancy-induced changes in liver blood flow and/or competition for the liver uptake of sexual hormones might interfere with the hepatic clearance of vecuronium in postpartum patients and thereby cause the observed prolongation of neuromuscular blockade.

[Initial experience with a new blood pump]

A new type of blood pump was tested in calves for 6 hours. The pump consists of a rigid housing with a trochoidal internal surface, an inlet and outlet, and two lateral walls. A two-corner piston rotating on an eccentric shaft, describes a trochoidal path, thus creating a gap seal, the gap measuring a constant 10-35 microns. The pump is driven by a watercooled DC motor. For right ventricular assist, a cannula is inserted into the right ventricle through the right atrium, and into the left ventricle for left ventricular assists. From a total of 10 experiments, two left ventricular assists, two right ventricular assists, and three biventricular assists were evaluated. The pump produced a pulsatile flow of 31 at 70 rpm. Energy requirements were 2.19 watts for left, 2.06 for right, and 7.26 for biventricular assists. Plasma hemoglobin remained as low as 10 mg/dl during monoventricular, and increased during biventricular assists to 20 mg/dl after 3 hours, and returned to 16 mg/dl after 6 hours. From these preliminary results it is concluded that this new rotary blood pump may be suitable as a circulatory assist device.

[Plasma levels of atrial natriuretic peptide, cyclic guanosine monophosphate and renin following 7.5% NaCl + 6% hydroxyethyl starch or Ringer's lactate. A comparative study of 6 normal subjects]

Small-volume resuscitation with hypertonic saline in combination with dextran appears to be very successful in experimental animals, where better results are achieved than in animals treated with a traditional infusion regime. This effect is apparently related to improved organ blood flow due to reflex vasodilatation. This reflex is based on the arrival of hypertonic solution in the pulmonary circulation. The expansion of intravascular volume would seem to be of secondary importance. Atrial natriuretic peptide (ANP) is released from secretory granules located in atrial cardiocytes. Atrial distention appears to be the predominant stimulus triggering ANP production. In addition to the natriuretic and diuretic effects, ANP leads to vasodilation, especially when vascular tone is elevated; the sympathetic reflex seems to be attenuated. Cyclic Guanosine Monophosphate (cGMP) is an intracellular messenger and is partly released by ANP in the membrane-bound form. Renin excretion is highly influenced by ANP. The object of this study was to evaluate the influence of a hypertonic solution on this hormonal regulatory system. METHOD. This study compared a hypertonic sodium chloride solution (7.5%) in combination with hydroxyethyl starch (6%) (HH) to Ringer's lactate (RL). Six healthy volunteers received 4 ml/kg HH and 1 week later 500 ml RL. The infusion was administered in 20 minutes via a central venous catheter 70 cm in length. Blood pressure, heart rate, hemoglobin (Hb), hematocrit (Hk), colloid osmotic pressure (COP), sodium (Na+), chloride (Cl-), and plasma osmolarity were measured before starting and 5 and 30 min following infusion. At the same times ANP, cGMP, and plasma renin were also determined. RESULTS. Both groups showed no change in blood pressure or heart rate. The decrease of Hb, Hk, and COP in the HH and RL groups indicated the expansion of circulating plasma volume. HH infusion caused significant increases in ANP and cGMP, whereas plasma renin declined significantly. After RL infusion, ANP and renin values were very similar to the HH group except in one volunteer, who showed an extreme increase in ANP (760 pg/ml) 5 min after HH infusion. cGMP did not increase significantly in the RL group. On comparison of the two groups, only a significant difference in plasma osmolarity and in sodium and chloride levels was noted. CONCLUSION. We found that hypertonic NaCl (7.5%) with HH was well tolerated. Release of ANP and cGMP after HH infusion in healthy volunteers was not as high as expected, and the vasodilatory effect of hypertonic solutions was not explained by ANP or cGMP release in this investigation.

[The dose-response relationship and time course of the neuromuscular blockade by alcuronium]

Although alcuronium has been in clinical use for almost 40 years, there is still considerable controversy in the literature regarding its neuromuscular blocking potency, the time course of the drug action and the side effects. The aim of this study was to investigate the dose-response relationship of alcuronium and to compare the time course of its neuromuscular effects with vecuronium following intubation doses of both compounds. METHODS. The study was carried out in two parts. In the first part 60 patients and in the second part 30 consenting ASA class I or II patients 20-60 years of age were included. The patients were undergoing elective gynecological or intra-abdominal operations. In the first part the patients received six different doses of alcuronium (60, 90, 120, 150, 180 or 210 micrograms/kg) in order to establish its dose-response relationship. Each dose was administered to ten patients. In the second part patients received either 300 micrograms/kg alcuronium (n = 15) or 100 micrograms/kg vecuronium (n = 15), and the time course of these two compounds (onset time, duration 25%, duration 75% and the recovery index) were compared. To test the reversibility, ten patients in each group received 30 micrograms/kg neostigmine at 25% recovery of T1. The neuromuscular effects of alcuronium and vecuronium were quantitated by EMG using the DATEX relaxograph. RESULTS. The log-logit analysis of the dose response data revealed an ED50 of 111 micrograms/kg and an ED95 of 250 micrograms/kg, which is in reasonable agreement with the measured effects following 120 micrograms/kg and 210 micrograms/kg alcuronium, resulting in 52 +/- 21% and 96 +/- 4% T1 depression, respectively. The onset time, duration 25%, duration 75% and spontaneous recovery index following 300 micrograms/kg alcuronium (5.0 +/- 3.4 min, 62 +/- 25 min, 119 +/- 38 min and 58 +/- 34 min) appeared to be significantly longer (P less than 0.05) than those observed after 100 micrograms/kg vecuronium (3.2 +/- 1.2 min, 33 +/- 7 min, 49 +/- 9 min and 18 +/- 7 min), respectively. The most striking finding of this study is the enormous individual variations observed in both neuromuscular potency and the time course of action of alcuronium. Following 150 micrograms/kg (routinely employed in daily clinical practice), the magnitude of T1 depression ranged between 19% and 100%. The same vast individual variations were observed in the time course of action following 300 micrograms/kg of alcuronium. The onset time, duration 25%, duration 75% and spontaneous recovery index ranged between 1.3 and 14 min, 22 and 110 min, 93 and 186 min and 32 and 116 min, respectively. CONCLUSIONS. The ED50 and ED95 values for alcuronium found in this study are in the same order of magnitude as 106.8 micrograms/kg and 135 micrograms/kg for ED50 and with 280 micrograms/kg for ED95, respectively, as reported by others. The long duration with slow recovery and the wide individual variation in the neuromuscular effects observed in our study have been reported earlier. Based on the above observations and because of the availability of better alternatives with fewer side effects, we conclude that alcuronium should be added to the list of obsolete neuromuscular blocking agents, together with gallamine and d-tubocurarine.

Rotacor: a new rotary blood pump

A new rotary blood pump was tested in calves for 6 hr. The pump consists of a rigid housing with a trochoidal internal surface, an inlet and outlet, and two lateral walls. A two-corner piston rotates on an eccentric shaft in a trochoidal path, thus creating a gap seal. The pump is driven by a water-cooled DC motor. For right ventricular assist, a cannula was inserted into the right ventricle through the right atrium, and into the left ventricle for left ventricular assist. From a total of 10 experiments, two left ventricular assists, two right ventricular assists, and three biventricular assists were evaluated. The pump produced a pulsatile flow of 3 L at 70 rpm. Energy requirements were 2.19 watts for left, 2.06 for right, and 7.26 for biventricular assists. Plasma hemoglobin remained as low as 10 mg/dl during monoventricular, and increased during biventricular assists to 20 mg/dl after 3 hr, when it started to chop again; after 6 hr it was 16 mg/dl. From these preliminary results it is concluded that this new type of blood pump may be suitable as a circulatory assist device.

[The effect of donor conditioning and perioperative management of recipients on the initial and late function of kidney transplants]

On the basis of 88 consecutive cadaveric renal transplants, multiple variables concerning donor conditioning and perioperative recipient management which may have an influence on the occurrence of acute tubular necrosis (ATN), were analysed and their impact on long-term results assessed. Cold ischaemia time turned out to be the greatest risk factor and was seven hours shorter in patients with good initial function when compared with patients with ATN. Although actual one-year graft survival was similar in both groups, the postoperative course was more complicated in the ATN group and management more onerous. Furthermore, two patients of the initial non-function group died of complications directly related to renal replacement therapy. Seventeen hours cold ischaemia time was associated with more than 80% initial function. This time is sufficient to allow careful tissue typing and organ transportation.

Studies of the mechanism of tolerance induced by short-term immunosuppression with cyclosporine in high-risk corneal allograft recipients. I. Analysis of CTL precursor frequencies

Transplantation of unmatched allogeneic corneas into highly vascularized recipient eyes under the cover of short-term immunosuppression with cyclosporine enables permanent engraftment. The aim of this study was to further elucidate the mechanism(s) underlying this tolerant state. In eight "high-risk" cornea recipients the clone sizes of donor-specific and third-party reactive cytotoxic T cell precursors were assessed by limiting dilution analyses before and at three and six months after transplantation. Acquired allograft tolerance in these patients was not accompanied by clonal reduction of donor-specific CTL-p, whereas in the case of an irreversible rejection the donor-specific CTL pool size was significantly enlarged. This donor-specific CTL-p increase could already be seen two months before clinical manifestation. These patterns differed from that of tolerant renal transplant patients, in whom marked and donor-specific reduction of CTL-p was observed. During rejection identical patterns with increasing donor-specific CTL-p frequencies were seen in both groups of patients. We conclude that induction of tolerance by short-term CsA to unmatched cornea grafts is not caused by clonal reduction of the effector precursor cell pool.

Delayed neurological sequelae of high-tension electrical burns

Five patients showed delayed spinal cord damage following high-tension electrical injury. Early specialist care of this complication is necessary and is best carried out in burn units. Our experience shows that recovery may be complete or only partial.

[The contribution of x-ray computed tomography in acute pancreatitis]

In acute pancreatitis. CT realize the best morphological examination not only for pancreas but also for extrapancreatic spread. However, ultrasonography is necessary for biliary lithiasis detection. Prognostic value of CT findings remains controversial and further studies are needed to clarify this problem. CT also permits to survey evolution and to detect eventual complications. Interventional CT, consisting in single-step needle aspiration or catheter drainage, allows in selected cases to avoid an unnecessary surgery.