[Effect of duration of infusion on elimination rate of alfentanil]. / Einfluss der Infusionsdauer auf das Eliminationsverhalten von Alfentanil.

In the present study the disposition of alfentanil after cessation of a constant rate infusion was compared with intravenous bolus injections. In 11 patients undergoing intervertebral disk surgery general anaesthesia was induced with midazolam, alfentanil and vecuronium; anaesthesia was maintained with a constant rate infusion (1.5 to 2 micrograms/kg/min, 1.0 micrograms/kg/min at the end of the infusion period) of alfentanil. The parameters of bolus injections were obtained from 5 patients undergoing lithotripter therapy; an intravenous bolus of 15 micrograms/kg was given. After infusion times of 60 to 120 minutes the mean elimination half life of alfentanil was significantly increased (227 +/- 166 min) compared to the bolus injection (50.8 +/- 9.5 min). There were significant correlations of the elimination half life with the age (r = 0.53, p = 0.03) of the patients, the total dose (r = 0.607, p = 0.01) and the infusion time (r = 0.612, p = 0.01). The total clearance of alfentanil in the bolus group was 385 +/- 138 ml/min and in the infusion group 620 +/- 215 ml/min. There were no significant correlations between the total clearance of alfentanil and the total dose and between the duration of infusion and total clearance. The clinical implications of our study: After prolonged continuous infusions of alfentanil a significant reduction of the elimination rate has to be considered. The patients must be observed very carefully in the recovery room in order to prevent a possible respiratory depression.

Simultaneous measurement of cardiac output by thermodilution, thoracic electrical bioimpedance and Doppler ultrasound.

To evaluate the accuracy of two non-invasive techniques for cardiac output (CO) measurement, we have measured CO simultaneously by thoracic electrical bioimpedance (TEB), pulsed Doppler ultrasound (DU) and standard thermodilution methods (TD) under different clinical conditions. Measurements were made in 10 patients: (I) during steady state anaesthesia with controlled IPPV ventilation (n = 131), spread over the entire ventilatory cycle; (II) during apnoea (n = 56); (III) during spontaneous breathing (n = 152) in the intensive care unit. Mean (SD) cardiac output values were: (I) COTD 3.5 (1.0) litre min-1, COTEB 3.4 (0.7) litre min-1, CODU 2.8 (0.7) litre min-1; (II) COTD 3.6 (0.6) litre min-1, COTEB 3.5 (0.4) litre min-1, CODU 2.9 (0.7) litre min-1; (III) COTD 7.7 (1.5) litre min-1, COTEB 7.6 (1.9) litre min-1, CODU 5.2 (1.4) litre min-1. The mean percentage deviation of TEB from TD ranged from -2.2% to 1.4% and that of DU from TD was from -16% to -32%. There were no statistically significant differences between TD and TEB, but TD and DU differed significantly during IPPV, apnoea and spontaneous ventilation (P < 0.0001).

Urapidil permeates the intact blood-brain barrier.

OBJECTIVE: To determine the plasma and cerebrospinal fluid (CSF) levels of urapidil after i.v. administration and the effect on CSF serotonin and 5-hydroxyindoleacetic acid (5-HIAA) concentrations. DESIGN: Open, single-dose study. SETTING: Post-surgery following neurosurgical removal of the hypophysis (n = 5) or aneurysm clipping (n = 1). PATIENTS: 6 patients, aged 32-71 years, with intact blood-brain barrier (BBB); 1 patient was studied twice. INTERVENTIONS: Single dose of 25 mg urapidil i.v. as prophylaxis of BP increase during extubation or as treatment of hypertensive episodes. MEASUREMENTS AND RESULTS: Urapidil, serotonin and 5-HIAA were measured by HPLC in CSF during 8 h after urapidil administration. Urapidil was detected in CSF as soon as 5 min after injection in 3 patients. The concentration ratio of plasma/CSF after the distribution phase was about 5:1. No significant effect on serotonin and 5-HIAA in CSF was seen. CONCLUSION: After administration of a therapeutic dose, urapidil permeates the BBB and may interact with central 5-HT1A-receptors.

[The behavior of the stress hormones cortisol, somatotropin (STH) and prolactin during anesthesia induction with midazolam-alfentanil in comparison with thiopental]. / Verhalten der Stresshormone Cortisol, Somatotropin (STH) und Prolactin bei Narkoseinduktion mit Midazolam-Alfentanil im Vergleich zu Thiopental.

In the present study, not only circulatory parameters but also serum concentrations of the stress hormones cortisol, Somatotropin and prolactin after endotracheal intubation were determined during narcosis. In 19 patients undergoing neurosurgical vertebra disc operations, general anaesthesia was induced with midazolam and alfentanil, while a control group of 8 patients was given thiopentone. The stress hormones were determined by radioimmunoassay immediately prior to and 1, 3 and 6 minutes after intubation. The induction of anaesthesia with the combination midazolam-alfentanil resulted in considerably fewer alterations of hemodynamic parameters such as arterial blood pressure and heart rate than the induction with thiopentone in both groups could be observed. A direct effect of thiopentone and midazolam on prolactin release could be excluded in a comparative study in which comparable amounts of these substances were administered without intubation. After alfentanil a slight, insignificant rise in the prolactin level occurred. Evaluation of such a short stimulus as endotracheal intubation by so-called stress hormones has not yet been satisfactorily achieved.

[Oral premedication with midazolam in children]. / Die orale Prämedikation mit Midazolam bei Kindern.

One hundred children aged between 6 months and 10 years undergoing elective urological surgery, received 0.4 mg/kg midazolam orally about 20 minutes prior to the arrival in the operation theatre. The physiological state of the children was estimated and recorded pre- and postoperatively at defined, comparable and representative circumstances by a specially developed design. In the preoperative period orally administered midazolam had only a mild or non sedative effect in 76-84% of the children, 67-88% of the small patients behaved cooperatively or passively and 70-84% showed an indifferent or euphoric state of mind. Postoperatively 57-89% of the children were markedly sedated; therefore, the estimation of behaviour and state of mind was of minor significance. The circulatory parameters were altered only minimally. Systolic blood pressure and heart rate changed slightly but significantly compared to the preoperative values the day before surgery: a preoperative increase to a maximum immediately after the insertion of the venous cannula and a postoperative maximum after recovery. Side effects were rare (hiccough 5%, vomitus 4%, laryngospasm 1%, stridor 1%). Our results suggest that oral premedication with midazolam in children can be recommended to avoid traumatic or unpleasant alterations resulting from intramuscular injections or rectal applications. Therefore, we prefer this kind of premedication in paediatric patients.

[Psychosomatic, sedative and hemodynamic reactions following preoperative administration of midazolam in children]. / Psychosomatische, sedative und hämodynamische Reaktionen nach präoperativer oraler Gabe von Midazolam bei Kindern.

Since children's intellectual perception is limited, the preoperative visit by an anesthesiologist alone can rarely help to free the small patients from fear and restlessness prior to elective surgery. In order to relieve anxiety which should be the primary goal of premedication in any patient - children need anxiolytic premedication agents. Drugs for premedication administered by intramuscular or rectal route in children often cause pain, fear and discomfort. The present study was performed in order to investigate oral given midazolam in the premedication of children with special regard to the practical suitability of this method. 100 children, 0.5 to 10 years of age (group A: 0.5-4 years, group B: 5-10 years) undergoing elective urological surgery received 0.4 mg/kg midazolam orally about 20 minutes prior to the arrival in the operation unit. After insertion of a venous cannula into a forearm vein anesthesia was induced with thiopental and maintained by inhalation with Isoflurane, nitrous oxide and oxygen (fi O2:0.3). Degree of sedation, state of mind and behaviour (for 100 children) as well as blood pressure and heart rate (separately for group A and B) were registered preoperatively at defined, comparable and representative circumstances. Side effects prior and during induction phase of anesthesia were documented. The personal data are representative for a normal population of children with typical urological diseases. Oral administered midazolam had only a mild or non sedative effect in 76-84% of the children 70-84% of the small patients showed an indifferent or euphoric state of mind and 67-88% behaved cooperatively or passively.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of cardiac output during positive end-expiratory pressure--noninvasive electrical bioimpedance compared with standard thermodilution.

Many investigators have demonstrated the accuracy and reliability of thoracic electrical bioimpedance (TEB) in spontaneously breathing patients and under mechanical intermittent positive-pressure ventilation. Most of these studies showed a good correlation between TEB and invasive methods, such as thermodilution (TD) or the Fick method. But during PEEP, contrary results occur when comparing TEB and TD. In six patients undergoing neurosurgical interventions, TEB cardiac output measurements were compared during zero end-expiratory pressure (ZEEP) and during PEEP at 8 cm H2O with a low respiratory rate. The data revealed a good correlation during ZEEP (r = .93) and during PEEP (r = .91). There was no significant statistical difference when measuring cardiac output by TEB during ventilation with PEEP. During normal or decreased cardiac output, TEB overestimated cardiac output compared with TD, whereas TEB underestimated cardiac output compared with TD during increased cardiac output, especially during PEEP.

[A computer-assisted noninvasive monitoring system with graphic display of online determination of cardiovascular parameters]. / Ein computergestütztes nicht-invasives Uberwachungssystem mit graphischer Darstellung von on-line erfassten kardiovaskulären Parametern.

During anesthesia the cardiovascular system is usually assessed on the basis of heart rate and arterial pressure, although the most important hemodynamic measurement is that of flow. A method for the non-invasive measurement of cardiac output is based on thoracic electrical bio-impedance. The NCCOM3-R7 is a non-invasive cardiac output monitor that makes use of thoracic electrical bioimpedance, which has been shown to provide results comparable with thermodilution in various hemodynamic states both in animals and humans. A new on-line hemodynamic monitoring system has been developed using the non-invasive NCCOM3-R7 (BoMed) cardiac output monitor, a portable microcomputer (NEC Multispeed) in connection with a software package CDDP-1 (BoMed), a Dinamap automatic arterial pressure monitor (Critikon) and an additional 14" display. Every 16 heart beats the cardiac output monitor transfers 11 cardiodynamic parameters in ASCII-format to the microcomputer, where the data are stored. Using the CDDP-1 program the current cardiodynamic status of the patient is displayed numerically and graphically on the monitor screen. Mean arterial pressure is determined by Dinamap and the data must be entered manually in the menu. The program then calculates systemic vascular resistance and left ventricular work index, the CVP being set to 3 torr and PAOP to 6 torr. In the graphic display the current hemodynamic status is shown and the underlying situation is analyzed in terms of systemic vascular resistance and volume-dependent contractility. The reliability of this on-line monitoring system is demonstrated in a high-risk patient.(ABSTRACT TRUNCATED AT 250 WORDS)

[Postoperative monitoring following short duration surgery of the ear, nose and throat. Experiences with midazolam as an anesthesia induction agent]. / Postoperative Vigilanz nach kurzdauernden Eingriffen im Hals-Nasen-Ohren-Bereich. Erfahrungen mit Midazolam als Narkose-Induktionsmittel.

A combination of midazolam and alfentanil was used on 24 patients for induction of general anaesthesia. Anaesthesia was maintained with N2O/O2 and repeated injections of alfentanil. The mean operation time was 40.8 min. At the end of surgery the patients recovered 4.8 min after antagonisation of the alfentanil with naloxon, and the endotracheal tube could be removed. Thirty, 60 and 120 min after extubation the patients were asked to perform a Marschner's test, which measures the ability to concentrate on fast intellectual work. Up to 660 simple arithmetical additions could be checked within 7.5 min. The intellectual performance recovered quickly: after 30 min 79% of the pre-operative values were reached, after 60 min 85% and after 120 min 90%. Midazolam is suitable as an induction agent for shortlasting otorhinolaryngological surgery.

[Intra- and postoperative effect of various plasma substitutes on blood rheology and conjunctival oxygen partial pressure in microsurgical intervertebral disk operations]. / Intra- und postoperativer Einfluss verschiedener Plasmaersatzmittel auf die Fliessfähigkeit des Blutes und den konjunktivalen Sauerstoffpartialdruck bei Mikrobandscheibenoperationen.

In a prospective, randomized, controlled, parallel group study the effect of different infusion solutions (HES 200/0.5 10%, dextran 40 10% and electrolyte solution) during and after intervertebral disc microsurgery on blood fluidity and conjunctival partial oxygen pressure was measured. At the beginning of the operation all patients showed a reduction in conjunctival oxygen pressure - independent of the infusion solution. Both fluidity of blood and oxygen partial pressure changed according to the plasma substitute used. Thus after the administration of medium molecular weight hydroxyethyl starch an improvement in the fluidity of blood with a consecutive significant increase in the conjunctival oxygen pressure could be observed, whereas there was no increase after the administration of electrolyte solution and only a slight one (according to tendency) after infusion of dextran.