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Objective: Blockade of the stellate ganglion is an established and highly effective diagnostic and therapeutic procedure for management of certain acute and chronic pain syndromes or other disorders. The paratracheal injection of a local anaesthetic is the simplest and most frequently used approach for blocking the cervicothoracic sympathetic nerves (ganglion stellate). However, since serious complications can occur during or following the anterior paratracheal technique including accidental intravenous or intraarterial injection, non-invasive methods for blockade of the stellate ganglion have been suggested. In 1980 Jenkner (15) reported the successful interruption of the sympathetic outflow from the stellate ganglion together with the relief of pain by transcutaneous electrical nerve stimulation (TENS), followed by the development of an "optimal wave form" in 1981 (14). Since we were unable to reproduce Jenkner's results of sympathetic blockade in our patients, this study was designed to investigate the effects of TENS on the sympathetic activity of the stellate ganglion in healthy volunteers., Methods: 50 healthy volunteers were randomised into two groups (n = 25). In group I the left stellate ganglion was stimulated for 20 min by the mode described by Jenkner (monophasic pulse, small anode, large cathode, frequency 20 Hz), while group II was stimulated by conventional TENS (biphasic pulse, electrodes of identical size, frequency 100 Hz). The method of stimulation was blinded to both the investigator and the subjects investigated. Measurements included cutaneous blood flow of the volar forearm (laser Doppler), skin temperature on two sites of the cheeks (thermistor), pupil diameter and size of the palpebral fissures, sweat production (ninhydrine test) and global sensitivity and pain perception thresholds on both sides (electrical stimulation). Measurements were performed before TENS of the stellate ganglion, after 5, 10, 15 and 20 min of stimulation and 10 min after termination of TENS. Statistical analysis of the obtained data was performed by Friedman-Test and by Mann-Whitney-U-Test. p < 0.05 was assigned statistical significance., Main Results: Skin temperature increased in both groups and on both sides by 1.2 degrees C, while skin perfusion rate, pupil size, size of the palpebral fissure and sweat production remained unchanged. Global sensitivity and pain perception thresholds of forehead decreased in both groups and on both sides, while there was no change of both parameters on the hands., Conclusion: No signs and symptoms of sympathetic blockade could be demonstrated in any of the groups, neither by TENS of the stellate ganglion as described by Jenkner nor by unspecific TENS. Thus, pain relief by TENS of the stellate ganglion as reported in the literature must involve other mechanisms than sympathetic blockade. In addition, TENS may not replace traditional blockade of the stellate ganglion by local anesthetics, if sympathetic blockade is required for diagnostic and therapeutic purposes.

Objective: Increasing age and anaesthetics diminish the baroreflex response to acute changes in blood pressure. This study was designed to investigate the effects of propofol and the combination of propofol with fentanyl on the baroreflex activity in geriatric patients., Methods: Baroreflex sensitivity was studied by the method of Smyth et al. in 10 elderly (72 +/- 6 yrs) and in 10 younger (48 +/- 6 yrs) patients. Nitroprusside (depressor test) and phenylephrine (pressor test) were used to induce changes in blood pressure of 20 mmHg each to alter the stimulation of the baroreceptor sites. Anaesthesia was induced with propofol, 2 mg x kg-1 b.w.m, and maintained by a continuous infusion of 12 mg x kg-1 x h-1 for 10 min and thereafter with 6 mg x kg-1 x h-1. Then a bolus of fentanyl, 7 micrograms x kg-1 b.w. was injected. Haemodynamic parameters and baroreflex activity were measured in the awake state, 10 min after induction of anaesthesia and 10 min after the administration of fentanyl. Plasma propofol concentrations were determined by HPLC 10 min after induction of anaesthesia with propofol and 10 min after injection of fentanyl. The slope of the linear regression changes in RR-interval [ms] per changes in systolic pressure [mmHg] was used as an index of the baroreflex sensitivity., Results: In the awake state the depressor slopes were significantly reduced by 60% in the elderly patients when compared to the younger patients. In both groups propofol decreased reflex sensitivity by 38% and 41% respectively; this effect was enhanced by the addition of fentanyl in the younger patients, while there was no further effect in the elderly. The pressor slopes did not change significantly in both groups neither with propofol nor with the combination of fentanyl, but again reflex response was significantly less in the elderly patients., Conclusion: Our data demonstrate that in geriatric patients the baroreflex control of heart rate already is attenuated in the awake state. Propofol produces a further reduction in reflex sensitivity to an acute decrease in blood pressure; this effect is more pronounced in elderly patients as compared to younger individuals. Acute changes in posture or circulating blood volume during propofol anaesthesia may result in greater cardiovascular instability in older patients due to the greater impairment of circulatory control mechanisms.

Objective: Neuromuscular blocking drugs may produce cardiovascular effects by virtue of drug-induced release of histamine or other vasoactive substances from circulating mast cells, effects at cardiac muscarinic receptors or effects at nicotinic receptors at autonomic ganglia. These haemodynamic reactions may be more pronounced in elderly patients, since cardiovascular compensating mechanisms are attenuated with advancing age. The present study was designed to investigate the cardiovascular effects of atracurium with special regard to the reactions in younger adults and in elderly patients., Methods: 20 patients, ASA class I-II, who underwent a neurosurgical operation (posterior fossa surgery) were studied. The patients were divided into two groups including patients below (group A) and above (group B) 65 years of age. Anaesthesia was induced with propofol (2.5 mg/kg) and maintained with a Propofol/O2/N2O sequence. Under steady state conditions with propofol every patient received 0.5 mg/kg atracurium besylate. Haemodynamic parameters were recorded and plasma concentrations of epinephrine and norepinephrine were determined before (control) and 2, 5 and 10 minutes after the injection of the neuromuscular blocking agent. All measurements were performed before surgical stimulation in supine position., Results: In the younger adults diastolic blood pressure and systemic vascular resistance decreased significantly 2 minutes after injection of atracurium and reached control level 5 minutes after application of the muscle relaxant. In the elderly patients peripheral vascular resistance decreased significantly after 5 minutes and returned to control 10 minutes after the application of atracurium. In both groups cardiac index, systolic and mean arterial pressure, central venous pressure and the parameters related to the pulmonary circulation were not affected. Plasma concentrations of epinephrine and norepinephrine remained essentially unchanged. Side effects due to a release of histamine such as facial or body blush or bronchial spasms were not noted., Conclusion: Since the results of the present study suggest that haemodynamic reactions in younger adults and in the elderly are rare, atracurium can be recommended for neuromuscular blockade in elderly patients under propofol anaesthesia.