Acute moderate hyponatraemia and its rapid correction: effects on striatal and pontine ultrastructure in an animal model of the TURP syndrome.

BACKGROUND AND OBJECTIVE: To investigate the effects of moderate hyponatraemia, induced by intravenous application of an electrolyte-free irrigation fluid, as a model of the human transurethral prostate resection syndrome and of its rapid correction by hypertonic saline infusion in rats. METHODS: Experimental animals received irrigation fluid (Purisole SM) 20 mL kg(-1) body weight, intravenously. In one group, hyponatraemia was subsequently rapidly corrected by infusion of hypertonic saline (NaCl 5.85%), while rats of group two were 'sham-corrected' by infusion of a balanced salt crystalloid solution. Plasma sodium concentrations were analysed during and at the end of the experiments. After 10 days, experimental and untreated control animals were killed humanely, fixed by perfusion and the brains were prepared for electron microscopic investigation of myelin sheets and glial cell numbers in the striatum and pons. RESULTS: The myelin appearance was unaltered in experimental groups compared to controls, but glial cell numbers were distinctly altered in the pons but not in the striatum. In the pons, oligodendrocytes were significantly reduced in number upon rapid correction of hyponatraemia, while astrocyte numbers were increased in rats with uncorrected hyponatraemia. CONCLUSIONS: Our electron microscopic data demonstrate that the effects of hyponatraemia and of its rapid correction are multifarious in animals. This may also apply for human patients during transurethral prostate resection.

[Intubation requirements after rocuronium and succinylcholine]. / Intubationsbedingungen nach Rocuronium und Succinylcholin.

OBJECTIVE: Rocuronium is a new non-depolarising steroidal muscle relaxant with a short onset time. The present study was undertaken to compare intubating conditions as well as onset and clinical duration of a single dose of 0.6 mg/kg (2 x ED95) with a single dose of 1 mg/kg suxamethonium (3 x ED95). METHODS: After obtaining informed consent and approval of the Ethics Committee, 40 adult patients (ASA I-III) participated in this study. After premedication with oxazepam, anaesthesia was induced with fentanyl and propofol and maintained with propofol, N2O and supplements of fentanyl as needed. Muscular relaxation was assessed by EMG recording of adductor pollicis muscle after supramaximal single twitch stimulation of the ulnar nerve every 10 s. Patients were allocated randomly to receive either rocuronium 0.6 mg/kg or suxamethonium 1 mg/kg. The following parameters were measured: intubating conditions 60 s after injection, onset time and clinical duration of neuromuscular block, % block at intubation, heart rate, blood pressure and arterial oxygen saturation. RESULTS: (mean +/- SD). Intubating conditions after rocuronium and suxamethonium were found to be clinically acceptable (excellent or good) in 90% of patients, though there was only a partial blockade of the adductor pollicis muscle with rocuronium (71 +/- 23%) compared to suxamethonium (95 +/- 14%) (p < 0.05). The onset time and clinical duration of relaxation was shorter after suxamethonium (p < 0.05) and occurred at 0.8 +/- 0.2, 7 +/- 2.1 and 3.2 +/- 1.3, 29 +/- 11 min after suxamethonium and rocuronium respectively. CONCLUSION: At a dosage of 0.6 mg/kg, rocuronium has an onset time of about 3 min and a clinical duration of relaxation of nearly half an hour. These data are supported by various studies, while others show shorter times, probably due to different monitoring techniques. In spite of the pharmacodynamic differences between suxamethonium and rocuronium, the intubating conditions after administration of both compounds are comparable and develop at the same rate.

[What's new in cardiopulmonary resuscitation? American Heart Association]. / Was ist neu in der kardiopulmonalen Reanimation?

A strong consensus was reached for several changes in the guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC) in the 1992 conference on CPR and ECC held by the Emergency Cardiac Care Committee of the American Heart Association. These new recommendations, together with differing recommendations of the European Resuscitation Council, are described. An unresponsive person with spontaneous respirations should be placed in the recovery position if no cervical trauma is suspected. Compared with endotracheal intubation, other airway-protecting devices such as combination esophageal-tracheal tubes are of minor acceptance. During ventilation, the time for filling the lungs is increased to 1.5-2 s to decrease the likelihood of gastric insufflation. Delivery of i.v. drugs can be enhanced by an i.v. flush of sodium chloride. In endotracheal drug administration, higher doses and drug dilution are recommended. In infants and children up to 6 years of age, the value of intraosseous drug administration is emphasized. For pulseless adult victims, the initial dosage of epinephrine of 1 mg i.v. remains unchanged. For repeat doses, high-dose epinephrine up to 0.1 mg/kg is classified as of uncertain but possible efficacy. For lidocaine, the recommended i.v. dosage is 1.5 mg/kg. Sodium bicarbonate and calcium are not routinely recommended for resuscitation. For atropine, the maximum dose is 0.04 mg/kg. If hypomagnesaemia is present in recurrent and refractory ventricular fibrillation, it should be corrected by administration of 1 to 2 g magnesium sulfate i.v. Thrombolytic agents are classified as useful and effective in acute myocardial infarction and should be administered as early as possible. Glucose-containing fluids are discouraged for resuscitative efforts.