Biomedical subjects

J Nadstawek

Publications and source records attributed to J Nadstawek.

At least 19 recordsLinked to original sources

PubMed2006

The effects of morphine on human 5-HT3A receptors.

5-HT3 receptors are ligand-gated ion channels that are involved in the modulation of emesis and pain. In this study, we investigated whether the opioid analgesic, morphine, exerts specific effects on human 5-HT3 receptors. Whole-cell patches from HEK-293 cells stably transfected with the human 5-HT3A receptor cDNA were used to determine the effects of morphine on the 5-HT-induced currents using the patch clamp technique. At negative membrane potentials, 5-HT induced inward currents in a concentration-dependent manner. The 5-HT3 receptor antagonist, ondansetron, (0.3 nM) reversibly inhibited the 5-HT-induced signals. Morphine reversibly suppressed 5-HT-induced peak currents as a function of concentration (IC50 = 1.1 microM, Hill coefficient = 1.2). The block by morphine decreased with increasing 5-HT concentrations, suggesting a competitive effect. In addition, the activation, as well as the inactivation, kinetics of the currents were significantly slowed in the presence of morphine. The morphine antagonist, naloxone, also inhibited 5-HT-induced currents (e.g., at 3 microM by 17%). The effects of morphine and naloxone were not additive. The potency of morphine and the competitivity of the blocking effect points to a specific mechanism at a receptor site rather than an unspecific membrane effect.

Animals↗

PubMed2003

[Managing patients with chronic orofacial pain in the outpatient departments of dental and maxillofacial surgeons. Results of a survey].

OBJECTIVE: The aim of this study was to evaluate the significance attributed by dental and maxillofacial surgeons to the ambulatory management of chronic orofacial pain syndromes. MATERIALS AND METHODS: All the dentists and oral and maxillofacial surgeons working in ambulatory capacities within a county of the German Rhine Area were asked to answer a questionnaire on demographic data, diagnostic and therapeutic principles, and the use of analogue scales, surgical, minimal-invasive or pharmacological procedures. RESULTS AND DISCUSSION: Seventy-two ambulatory institutions reported 985 patients suffering from temporomandibular disorders (40.2%), headache-syndromes associated with facial pain (18.2%), and atypical odontalgia respectively phantom tooth pain (17.0%). Patients were characterized by prior dental treatment or trauma (41.9%), female gender (66.8%), middle age (81.1%, 20-60 years), very frequent change of therapists (54.6%) and long-term perseverance of pain (61.1% >6 months). Only 7% of therapists used visual or numerical analogue scales to assess pain intensity. Therapeutic procedures consisted of analgesics (15.7%) and further surgical procedures (47.7%). Pain therapists were rarely involved (12.5%). CONCLUSION: Dental and maxillofacial surgeons should apply an interdisciplinary and multimodal approach to diagnostics and therapy at an earlier stage in order to optimize the pain management of patients with chronic orofacial pain.

Adult↗

PubMed1999

Influence of fentanyl, alfentanil, and sufentanil on motor evoked potentials.

The effects of the opioids fentanyl, alfentanil, and sufentanil on motor pathways were studied in a total of 30 rabbits. Compound muscle action potentials (CMAP) were recorded from the extensor muscles of the upper extremity as well as evoked spinal cord potentials (ESCP) from the thoracic epidural space in response to electrical stimulation of the motor cortex. After establishing stable baseline values, an equipotent intravenous bolus of one of the three opioids was applied that abolished reflex motor response to noxious stimulation. Motor evoked potentials (MEP) were recorded from the time of bolus administration until recovery of MEP amplitudes and latencies. Afterwards, the opioids were administered continuously with cumulative dosage up to total absence of motor evoked response. Our results show a dose-dependent suppression of the CMAP: When reflex movement to noxious stimulation was extinguished, we found a significant (P < .001) reduction of the amplitudes to 34+/-18% (mean +/- SD) in the fentanyl group, to 43+/-24% in the alfentanil group, and to 53+/-20% of baseline values in the sufentanil group. Increasing opioid plasma levels were associated with complete extinction of the CMAP. We hypothesize that the descending volleys within motor pathways are mainly inhibited at a spinal level, because ESCP, particularly the number of spinal I-waves, are not severely affected even when CMAP are completely suppressed. In conclusion, intraoperative monitoring of descending pathways by means of MEP during anesthesia with opioids is feasible at anesthetic plasma concentrations maintaining a surgical level of analgesia. Even with high opioid plasma levels, a valid MEP monitoring could be performed evaluating neural activity of spinal MEP.

Action Potentials↗

PubMed1998

Isoflurane plus nitrous oxide versus propofol for recording of motor evoked potentials after high frequency repetitive electrical stimulation.

The goal of this study was to test the influence of two widespread techniques of general anesthesia on motor evoked potentials (MEP) in response to transcranial and direct cortical high frequency repetitive electrical stimulation. Total intravenous anesthesia (TIVA) based on propofol and alfentanil was examined in 17 patients (group A), and balanced anesthesia (BA), based on nitrous oxide, isoflurane and fentanyl, was studied in 13 patients (group B). Distinct motor responses were available in 15 of 17 patients (88%) of group A, and in one of 13 patients (8%) of group B. Amplitudes increased significantly with increasing stimulus intensity and number of pulses under conditions of TIVA. At the same time, latencies decreased significantly with increasing stimulus intensity and decreasing interstimulus interval, but not with increasing number of pulses. It is hypothesized that propofol suppresses corticospinal I-waves at the cortical level, resulting in a conduction block at the level of the alpha-motoneuron, and that this effect may be overcome by high frequency repetitive stimulation. In contrast, nitrous oxide and isoflurane seem to have an additional suppressive effect on corticospinal D-waves, which may be overcome by higher stimulation intensity. In conclusion, transcranial high frequency repetitive stimulation and TIVA provide a feasible setting for intraoperative MEP monitoring, while higher doses of nitrous oxide and isoflurane are not compatible with recording of muscular activity elicited by the stimulation technique as described.

Adolescent↗

PubMed1997

Influence of nitrous oxide on motor-evoked potentials.

STUDY DESIGN: Rabbits were used as an experimental model in the study of motor-evoked potentials. OBJECTIVES: To evaluate the effect of nitrous oxide on motor-evoked potentials while monitoring direct muscle and spinal cord responses. SUMMARY OF BACKGROUND DATA: Motor-evoked potential monitoring provides a promising tool for intraoperative assessment of descending pathways function. However, to date, this technique is still at an experimental stage, since its routine use is mainly limited because of intraoperative recording difficulties caused by the influence of anesthesia. METHODS: Eight male rabbits weighing between 3000 g and 3500 g were studied. Motor-evoked potentials were recorded from the extremity muscles and from the epidural space of the thoracic cord in response to electrical stimulation of the motor cortex at baseline conditions and at increasing nitrous oxide concentrations (10-70 vol%). RESULTS: The authors found a major suppressive effect of high nitrous oxide concentrations on the electromyographic responses. With 50 vol% nitrous oxide, electromyographic amplitudes were suppressed to 46% (fore leg) and 14% (hind leg) of the baseline values, whereas latencies did not change significantly. In contrast to muscular activity, spinal evoked responses representing neural activity were not affected by any concentration of nitrous oxide. CONCLUSIONS: Intraoperative monitoring of descending pathways by means of motor-evoked potentials during anesthesia of the rabbits based on nitrous oxide is feasible when neural activity is evaluated. Higher doses of nitrous oxide, however, are not compatible with recording of muscular activity.

Anesthetics, Inhalation↗

PubMed1996

Transcranial high-frequency repetitive electrical stimulation for recording myogenic motor evoked potentials with the patient under general anesthesia.

OBJECTIVE: To demonstrate the feasibility of transcranial high-frequency electrical stimulation with the patient under general anesthesia with propofol and alfentanil. This method may be a useful tool for intraoperative monitoring of the motor pathways during cerebral and spinal operations. METHODS: A short train from one to eight monopolar anodal electrical pulses was applied transcranially to the motor cortex with a frequency from 100 to 500 Hz in 10 patients. Myogenic motor evoked potentials (MEPs) were recorded from forearm flexor muscles, thenar, and hypothenar. Amplitude and latency of MEPs were evaluated after different stimulation parameters. This combination of anesthetic and transcranial stimulation technique allows recording of myogenic MEPs during general anesthesia, which was found not to be possible with single pulse transcranial stimulation. RESULTS: To elicit myogenic MEPs from the target muscles, stimulation had to be applied within the following parameters: minimum threshold intensity was 60 mA for forearm flexor and thenar and 80 mA for hypothenar; minimum number of pulses was two for forearm flexor muscles and thenar and three for hypothenar; minimum stimulation frequency was 200 Hz for thenar and hypothenar and 100 Hz for forearm flexor muscles. CONCLUSION: Transcranial high-frequency repetitive electrical stimulation seems to be a new method for monitoring the motor tract. With this method, it is possible to monitor the motor function without interfering with the surgical team or with the surgical treatment of infratentorial and spinal lesions. Monitoring of relaxation is necessary to compare the amplitude of MEPs.

Adolescent↗

PubMed1995

[Effect of premedication and barbiturate hypnotics on motor evoked potentials induced by magnetic cortex stimulation].

OBJECTIVE: The aim of this study was to investigate the influence of the premedication and the influence of the two barbiturates methohexital and thiopental on magnetically evoked compound muscle action potentials (magnet MEP) in humans. METHODS: 40 Patients (ASA-PS I-II) undergoing lumbar nucleotomy were included in this study after obtaining written informed consent. The study was approved by the local ethical committee. All patients were premedicated with 0.5 mg atropine, 25 mg promethazine and 50 mg pethidine. For induction of anaesthesia patients randomly received methohexital or thiopental by continuous infusion with increasing infusion rates every 15 seconds up to a minimal anaesthesia level in 15 minutes. Transcranial magnetic stimulation was delivered by the magstim 200 magnetic stimulator. Magnetic MEPs were recorded from the surface of the short abductor pollices muscle. MEP-examination was performed preoperatively, after premedication and every two minutes during the induction of anaesthesia. Every other two minutes the patients level of consciousness were assessed and documented. Statistical calculations were performed with the U-test. RESULTS: No statistical differences were found for the mean induction time in the two groups. No statistical difference in amplitude and latency could be observed between the preoperative values and the values measured after premedication. During anaesthesia induction the amplitude decreased in both groups. In 25 of the 40 cases, the MEP disappeared completely before the patients fell asleep. The thiopental group showed a significantly lower incidence of MEP preservation (20%) compared to methohexital (50%). CONCLUSIONS: Premedication with atropine, promethazine and pethidine has no influence on magnetic MEP. Methohexital allows the highest incidence of successful MEP recordings with sufficient anaesthesia. A success rate of only 50% even in cases without motorpathway affection makes the application of magnetic MEP an unreliable tool for intraoperative monitoring.

Adjuvants, Anesthesia↗

PubMed1993

Effects of four intravenous anesthetic agents on motor evoked potentials elicited by magnetic transcranial stimulation.

The influence of four intravenous anesthetic agents on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (magnetic MEP) was examined in 77 subjects. The patients were anesthetized by a continuous intravenous infusion of one of the following anesthetic agents: propofol, etomidate, methohexital, or thiopental. Comparable anesthetic effects among the four agents were achieved by computing an infusion scheme for each drug. Infusion rates were increased slowly in a step-wise manner in order to reach minimal anesthetic blood concentrations within 15 minutes. During anesthesia induction, magnetic MEPs were recorded every 2 minutes from the abductor pollicis brevis muscle. The patient's level of consciousness was assessed and documented in the alternating minutes. A dose-related reduction of the MEP amplitudes was seen in all drug groups, while the latencies remained constant. Reduction of the amplitude was occasionally so prominent that the MEP was completely abolished before adequate anesthesia was achieved. MEPs were obtainable at the end of anesthesia induction in 14% of the propofol group (n = 22), 57% of the etomidate group (n = 21), 53% of the methohexital group (n = 19), and 20% of the thiopental group (n = 15). Propofol and thiopental showed significantly stronger suppression of MEP, when compared to etomidate (both P < 0.01) and to methohexital (P = 0.01 and 0.05, respectively). Etomidate was the least detrimental anesthetic agent for intraoperative monitoring of magnetic MEP. Nonetheless, the low incidence of 57% of preserved MEP in subjects without motor deficits indicated the inadequacy of this technique for intraoperative monitoring. More effective transcranial stimulation techniques are required for successful intraoperative MEP monitoring.

Adult↗

PubMed1992

[Muscle relaxation with no effect on oxygen uptake during isoflurane anesthesia?].

To determine the effects of vecuronium neuromuscular blockade on O2 consumption (VO2) during isoflurane anaesthesia 12 patients were studied. 12 patients (ASA-PS I-II, 37.1 +/- 12.1 yr, 173 +/- 8 cm, 70.1 +/- 8.6 kg), scheduled for urological lower abdominal surgery, received isoflurane-N2O-O2-anaesthesia under steady-state conditions (1.3 MAC). Duration of anaesthesia was 169 +/- 32 min and 0.057 +/- 0.016 mg/kg/h vecuronium were needed. The desired level of neuromuscular transmission was set to 10% of control. This level of neuromuscular blockade was kept constant for 60 min by a negative feedback controlled infusion of vecuronium. VO2 was measured by an indirect calorimetry device (MMC Horizon, STPD). During and after recovery of neuromuscular function anaesthesia was maintained and oxygen measurements were continued. Preanaesthetic values of VO2 were in the predicted range for basal metabolism. Steady-state general anaesthesia lead to an 26-28% reduction of VO2 (Range: 144-232 ml/min) compared to the preanaesthetic values (202-288 ml/min, p < 0.01). Neuromuscular blockade showed no significant effect on O2 uptake. We conclude that in patients with adequate depth of anaesthesia vecuronium-induced neuromuscular blockade does not lead to a further reduction of oxygen consumption, since muscular tone is already reduced by general anaesthesia.

Abdomen↗

PubMed1992

Total intravenous anesthesia for improvement of intraoperative monitoring of somatosensory evoked potentials during aneurysm surgery.

Two anesthetic regimens for monitoring somatosensory evoked potentials (SEPs) during intracranial aneurysm surgery were compared. Eighty-four sequential cases of intracranial aneurysms were operated on employing SEP monitoring. The first group of 22 cases was anesthetized with "balanced anesthesia" and the second group of 62 cases received total intravenous anesthesia (TIVA) consisting of propofol and alfentanil. In the TIVA group, the amplitude of early cortical SEP responses (N20-P25, or P40-N50) was significantly higher than that of responses in the balanced anesthesia group. In median nerve SEPs, the averaged amplitude of N20-P25 was 3.22 microV with TIVA and 1.69 microV with balanced anesthesia (P = 0.006). Similarly, posterior tibial nerve SEPs showed a P40-N50 response of 1.85 microV and 1.00 microV, respectively (P = 0.017). The superior signal-to-noise ratio obtained with TIVA allowed more frequent and reliable intraoperative SEP recordings than was possible with balanced anesthesia, resulting in rapid and reliable feedback for the surgeon. In 19% of median nerve SEPs recorded with TIVA, the cortical responses were over 5 microV in amplitude, so that reproducible N20-P25 responses were obtainable by averaging only 10 to 50 serial responses, that is, two to three recordings per minute. The higher amplitude of posterior tibial nerve SEPs recorded with TIVA made monitoring during surgery for anterior communicating artery aneurysms possible in all cases. This was not always the case with balanced anesthesia. The late deflection of median nerve SEPs (N30) was more frequently observed with TIVA.(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil↗

PubMed1992

[Total intravenous anesthesia using propofol and alfentanil as compared to combined inhalation anesthesia reduces the flow velocity in the middle cerebral artery. A Doppler sonographic study].

Anesthesia for craniotomies should guarantee hemodynamic stability, preservation of cerebral autoregulation, and rapid postoperative recovery of consciousness. Increases in intracranial pressure (ICP) and postoperative respiratory depression should be avoided. Combined anesthesia (KA) with N2O and volatile anesthetics may increase cerebral blood flow (CBF), ICP, and cerebral oxygen consumption. According to recent studies, total intravenous anesthesia (TIVA) with propofol and alfentanil seems to best fulfill the requirements. Using transcranial Doppler sonography (TCD) (TC2-64, EME), we studied the influence of TIVA and KA under normo- and hyperventilation on the blood flow velocity (BFV) and pulsatility of the middle cerebral artery (MCA). METHODS. Two groups of 10 patients each undergoing craniotomy were investigated. Systolic and mean BFV, pulsatility index, mean arterial blood pressure, heart rate, and arterial CO2 tension were measured at four time intervals: (1) preoperatively; (2) 15 min after anesthesia induction under normoventilation, preoperatively; (3) 25 min after anesthesia induction under hyperventilation, preoperatively; and (4) 6 h postoperatively. The patients were premedicated with flunitrazepam 1 mg PO. TIVA was induced with 60 mg propofol, 1 mg alfentanil, and 6 mg vecuronium; simultaneously infusions of propofol (15 mg/min) and alfentanil (0.3 mg/min) were started and were maintained until the dura was completely opened. The infusion rates were then reduced to 6 mg/min propofol until skin suturing and 0.1 mg/min alfentanil until dural suturing was completed. Patients were ventilated with O2/air (fiO2 = 0.5). In the KA group anesthesia was induced with 4-6 mg/kg thiopental, 0.15 mg fentanyl, and 6 mg vecuronium and maintained with boluses of fentanyl, N2O (fiO2 = 0.5), and isoflurane (1.3 MAC). The time course is illustrated in Figs. 1 and 2 and the results are shown in Tables 1 and 2. They were tested using a one-factor analysis of variance and the Kruskal-Wallis range test. RESULTS. There was a significant decrease in systolic and mean BFV combined with an increase in pulsatility index after induction of TIVA, while KA induction effected no significant change in cerebral hemodynamics. The subsequent hyperventilation caused a similar decrease in mean BFV and increase in pulsatility index in both groups. CONCLUSION. Using the assumption that the diameter of the MCA is nearly constant, the reduction in BFV associated with an increase in pulsatility during TIVA is explainable as a decrease in CBF. By having a comparable influence on hemodynamics, the reduction in CBF with increase in cerebral vascular resistance seems to make TIVA the more advantageous anesthesia technique for patients with reduced intracranial compliance.

Adult↗

PubMed1991

Barbiturates in severe head injuries?

Possible mechanisms for the therapeutic effects of barbituric acid derivatives in severe head injuries have been discussed for half a century. In the following, a survey of the literature, and a discussion of three controlled clinical studies available until now is presented. A proven effect in terms of a beneficial long-term outcome for all injured patients has not been established. On the other hand there might be a subgroup of patients with an intact CO2 reactivity of the brain vessels who may profit from barbiturates administered after head trauma.

Barbiturates↗

PubMed1991

[Optimal dosage strategies in total intravenous anesthesia using propofol and ketamine].

The combination of propofol and ketamine for total intravenous anesthesia was investigated; the intention was to minimize the side effects of each drug by the concomitant application of the other drug. METHODS. Twenty patients scheduled for lower abdominal interventions were divided into two groups. In the first group anesthesia was induced and maintained by a simple administration regimen based upon pharmacokinetic principles. Ketamine and propofol were given as bolus injections (60 mg each) with a time interval of 60 s for induction followed by a two-step infusion regimen for propofol (15.5 mg/min) and later on by an additional ketamine infusion (1-2 mg/min). Bolus injections (20 mg) of ketamine were administered to increase the depth of anesthesia if necessary (Fig. 1). The second group received propofol and ketamine by microprocessor-controlled infusion pumps requiring the anesthetist to operate a single dial to preset the desired blood levels of both drugs according to the needs of the individual patient (Fig. 2). RESULTS. There were no difference (Table 1) between the two groups in the demographic data of the patients or duration of surgery (30-120 min). The total doses of propofol (750 +/- 262 vs 624 +/- 468 mg) and ketamine (158 +/- 41 vs 99 +/- 48 mg) were smaller in the computer-controlled infusion group, though this difference just failed to be significant. The hemodynamic changes during induction were minor, with a small nonsignificant increase in all parameters (Fig. 3) for 10 min. The controllability of the pharmacodynamic effects of both drugs during anesthesia was very satisfactory in the computer-assisted infusion group and quite satisfactory in the first group. There were no psychic disturbances during induction of or recovery from anesthesia. Respiration was adequate within a few minutes after the end of surgery. The patients were awake about 10 min later and fully oriented after 20 min. No major side effects were observed with this anesthetic technique. CONCLUSION. Total intravenous anesthesia with propofol and ketamine proved to be very satisfactory from a clinical point of view. The major known side effects of propofol (reduced hemodynamics during induction) and ketamine (psychic disturbances and cardiovascular stimulation) were absent and respiratory function was adequate after the end of surgery. This technique, therefore, can be used in risk patients and under disaster conditions when i.v. access is the only possible route of drug administration. The use of computer-assisted infusion pumps markedly enhances handling and controllability of total i.v. anesthesia.

Adult↗

PubMed1991

[O2 uptake in the recovery period. The effect of the anesthetic procedure and the postoperative administration of pethidine].

UNLABELLED: General anesthesia leads to a marked reduction in oxygen uptake (VO2), but during the recovery period O2 consumption can increase dramatically. A controversial discussion has continued in the literature concerning the role of different types of anesthesia with regard to metabolic changes. The aim of this comparative study was to evaluate the effects of two different techniques for general anesthesia and of postoperative meperidine on VO2, especially in the postanesthetic recovery period. METHODS: Twelve patients (K1: ASA class I-II, age: 39.9 +/- 16.1 years, height: 176 +/- 10.1 cm, weight: 76 +/- 12.8 kg) scheduled for urological lower abdominal surgery were given isoflurane-N2O-O2 (1.3 MAC); another group of 12 patients (K2: ASA class I-II, 35.9 +/- 14.5 years, 181.8 +/- 11.4 cm, 77.3 +/- 8.4 kg) received total intravenous anesthesia (TIVA) with propofol and alfentanil (ED95). Both groups were studied under steady-state conditions. Duration of anesthesia was 124.2 +/- 27.5 min (K2) versus 139.2 +/- 35.5 min (K1). VO2 was measured by an indirect calorimetric device (MMC Horizon, STPD). RESULTS: Preanesthetic values of VO2 were in the predicted range for basal metabolism. Steady-state general anesthesia led to approximately 30% reduction in VO2 (K1: 121-225 ml min, K2: 107-230 ml/min) compared to preanesthetic values (P less than 0.05). Both groups showed an increase in VO2 during the recovery period. When compared to the preanesthetic measurements, only K1 showed a statistically significant change. Shivering was observed during the recovery period in 8 patients in K1 (max VO2: 639 ml min) and 2 in K2 (max VO2: 584 ml min (P less than 0.05). Meperidine (25 mg i.v.) given to 5 patients from K1 because of postanesthetic shivering decreased VO2 significantly to the range of VO2 measured in K2. CONCLUSION: Oxygen consumption during general anesthesia was not defined by the type of anesthetic administered. During the recovery period however, VO2 depended on the type of anesthetic, as muscular hyperactivity was prominent in the isoflurane group. Meperidine could suppress visible shivering and reduce postoperative VO2 to the levels seen after TIVA.

Adult↗

PubMed1990

[The recovery period following total intravenous anesthesia using propofol and alfentanil versus inhalation anesthesia using nitrous oxide and enflurane at 1.3 MAC].

Recovery of motor and mental functions were investigated in two groups with 20 young patients each. One group received total intravenous anaesthesia (TIVA) with propofol and alfentanil for urological surgery and the other group received nitrous oxide-oxygen anaesthesia in combination with 1.3 MAC of enflurane for lumbar nucleotomy. The following parameters were investigated before and up to 100 minutes after extubation: simple and discriminating motor activities, vigilance and short and long term memory. --Simple and in discriminating motor actions show a significantly faster recovery was seen in the TIVA group during the first 20 minutes after extubation compared to the enflurane-treated patients. Speech-related functions were particularly inhibited in the inhalational anaesthesia group. After 30 to 40 minutes the propofol-alfentanil group was able to meet all requirements while patients with inhalational anaesthesia needed 80 minutes to reach the same level. Recovery of short and long-term memory was also significantly shorter in the TIVA group. This clearly indicates a faster return of mental and motor functions following total intravenous anaesthesia with propofol and alfentanil. However the large dosages of alfentanil may be a problem with regard to post-anaesthetic respiratory depression. Further studies with larger numbers of patients will be necessary to evaluate the potential side effects of continuous propofol/alfentanil infusion. Presently, safety demands require, at least a sixty-minute post anaesthesia monitoring for patients receiving this new anaesthesia method.

Adult↗

PubMed1990

[Oxygen uptake and blood circulation parameters during anesthesia using EEG-assisted determination of anesthetic dosages].

Anaesthesia has significant effects on circulation and oxidative metabolism which are closely related to each other. Usually there is a marked reduction of oxygen uptake (VO2) and energy expenditure. A controversial discussion on the effects of the drugs administered and the degree of metabolic depression has continued in the literature fuelled by a lack of studies in patients under standardized conditions. 18 patients (ASA I-II) scheduled for major abdominal surgery were given closed-loop feedback control anaesthesia by quantitative EEG analysis. Group 1 received a total intravenous anaesthesia with methohexital and fentanyl whereas group 2 was given a combined anaesthesia with alfentanil and N2O. The aim of this comparative study was to evaluate the effects of different techniques for general anaesthesia on oxygen uptake and on the cardiovascular system. Preanaesthetic values of VO2 taken after flunitrazepam premedication were slightly below the predicted range determined by indirect calorimetry for basal metabolism. Steady-state general anaesthesia led to an approximately 30% reduction of VO2 for both groups. In contrast to oxygen uptake, blood pressure and especially heart rate were defined by the type of anaesthesia as in the methohexital fentanyl group higher values of both blood pressure and heart rate were observed.

Adult↗

PubMed1989

The influence of barbiturates on cerebral metabolism in patients with borderline cerebrovascular reserve during intraoperative transient carotid occlusion.

Sixty patients with borderline or frank insufficiency of their cerebrovascular reserve undergoing carotid endarterectomy were given enough short acting barbiturates, during cross clamping of the internal carotid artery, to cause EEG burst suppression. Arterial and venous concentrations of lactate were measured in blood samples taken before, 30 min after occlusion of the artery and 10 min after reperfusion. The amount of lactate produced depended on the length of time of burst suppression; the shorter it lasted, the larger the amount of lactate produced. Only in patients with the shortest burst suppression times did the blood lactate levels rise above normal levels. The lactate levels can be used as indicators of how effective barbiturates are being in preventing ischaemia during the time of carotid artery occlusion.

Barbiturates↗

PubMed1989

[Serum and cerebrospinal fluid kinetics of ceftazidime].

Ceftazidime serum concentrations and cerebrospinal fluid (CSF) penetration across non-inflamed meninges were evaluated in 10 patients after intravenous application of 2 g ceftazidime over a period of 30 min. After a continuous increase during infusion the highest level of ceftazidime in serum with 172.27 micrograms/ml (+/- 60.43 micrograms/ml) was ascertained at the end of the infusion. The further development demonstrated a continuous decrease of serum concentrations. Concentrations in serum followed a two-compartment open kinetic model. Mean distribution volume was 17.6 l, the total clearance was 142.97 ml/min, half-life was 1.8 h and the determined area under the curve was 139.89 micrograms x min/ml. Penetration of ceftazidime into CSF could only be pointed out in 5 patients. The highest level with 5.11 micrograms/ml (+/- 1.2 micrograms/ml) was observed 32 min after starting the infusion. A steady state with CSF-concentrations over 2 micrograms/ml could be ascertained during the following 4 hours in these patients. Obviously high statistic significance (p less than or equal to 0.01) was present when penetration into CSF was correlated to body surface area (BSA) using the exact Fisher test with Yates correction. Penetration of ceftazidime into CSF across non-inflamed meninges with therapeutic concentrations over a period of 4 hours could only be achieved when BSA was less than 1.95 m2. Further investigations in more patients are necessary to evaluate if BSA is the only parameter which affects distribution of ceftazidime into CSF.

Adult↗