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Biomedical subjects

T J Luger

Publications and source records attributed to T J Luger.

At least 19 recordsLinked to original sources
PubMed2003

Remifentanil and nitrous oxide reduce changes in cerebral blood flow velocity in the middle cerebral artery caused by pain.

BACKGROUND: Cerebral blood flow is affected by painful stimuli, and analgesic agents may alter the response of cerebral blood flow to pain. We set out to quantify the effects of remifentanil and nitrous oxide on blood flow changes caused by experimental pain. METHODS: We simulated surgical pain in 10 conscious volunteers using increasing mechanical pressure to the tibia. We measured changes in cerebral blood flow velocity in the middle cerebral artery (CBFV(MCA)) caused by the pain, using transcranial Doppler sonography. We gave increasing doses of remifentanil (0.025, 0.05 and 0.1 micro g kg(-1) min(-1)) or nitrous oxide [20%, 35% and 50% end-tidal concentration (FE'(N(2)O))] and compared these effects on blood flow changes. RESULTS: Nitrous oxide increased CBFV(MCA) only when given at 50% FE'(N(2)O). Remifentanil did not affect CBFV(MCA). Pain increased CBFV(MCA). Both agents attenuated this pain-induced change in CBFV(MCA) with the exception of nitrous oxide at 20% FE'(N(2)O). CONCLUSIONS: Inhalation of nitrous oxide or adminstration of remifentanil attenuated pain-induced changes in CBFV(MCA).

Adolescent↗
PubMed2002

The influence of nitrous oxide and remifentanil on cerebral hemodynamics in conscious human volunteers.

Remifentanil is increasingly used in the context of anesthesia, e.g., in patients presenting for MRI examinations, not only as an analgesic but also to replace nitrous oxide. Therefore, a comparative analysis of the effects of commonly used doses of remifentanil and of nitrous oxide on cerebral hemodynamics is warranted. The present study used contrast-enhanced magnetic resonance (MR) perfusion measurement to compare the effects of nitrous oxide (N(2)O/O(2) = 50%; n = 9) and remifentanil (0.1 microg/kg/min; n = 10) on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), and regional mean transit time (rMTT) in spontaneously breathing human volunteers. Remifentanil increased rCBF above all in basal ganglia, whereas in supratentorial gray matter the increase in rCBF was equal or even more pronounced when using nitrous oxide. In contrast, nitrous oxide produced a greater increase in rCBV in gray-matter regions than did remifentanil. In summary, nitrous oxide increased rCBV in all gray-matter regions more than did remifentanil. However, the increase in rCBF, especially in basal ganglia, was typically less pronounced than during infusion of remifentanil.

Adult↗
PubMed2001

Influence of equianaesthetic concentrations of nitrous oxide and isoflurane on regional cerebral blood flow, regional cerebral blood volume, and regional mean transit time in human volunteers.

Nitrous oxide and isoflurane have cerebral vasodilatory effects. The use of isoflurane in neuroanaesthesia is widely accepted, whereas the use of nitrous oxide in neuroanaesthesia is still the subject of debate. In the present study, contrast-enhanced magnetic resonance (MR) perfusion measurement was used to compare the effects of 0.4 MAC nitrous oxide (n=9) and 0.4 MAC isoflurane (n=9) on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and regional mean transit time (rMTT) in spontaneously breathing human volunteers. Nitrous oxide increased rCBF and rCBV in supratentorial regions more than did isoflurane. Isoflurane, by contrast, increased rCBF and rCBV in basal ganglia more than did nitrous oxide. An increased rMTT was caused by a relatively greater increase in rCBV than in rCBF supratentorially by isoflurane and infratentorially by nitrous oxide. In conclusion, nitrous oxide increases rCBF and rCBV predominantly in supratentorial grey matter, whereas isoflurane increases rCBF and rCBV predominantly in infratentorial grey matter.

Adult↗
PubMed2001

Cardiological monitoring of sailors via offshore Internet connection.

BACKGROUND: Sailing is becoming increasingly popular as a form of holiday recreation. The purpose of the present study was to profile the heart rate characteristics of non-professional crew members on a Mediterranean sailboat trip. Additionally, the practicability of transferring electronic data via the Internet while sailing offshore was also studied. METHODS: Seven healthy male non-professional crew members responsible for steering and navigating the boat during the observation period were studied using continuous electrocardiographic recording (Holter). Manually measured blood pressure, side effects and sailing data were taped half-hourly. RESULTS: While sailing we observed that the heart rate increased typically into the 120-170 beats/min range, mean arterial pressure remained stable between 80-90 mmHg. Heart rate changes and the incidence of supraventricular arrhythmias correlated with activity on board, boat speed and wind velocity. No subject showed ventricular arrhythmias during sailing. The minimal blood pressure changes correlated only with activity on board. CONCLUSIONS: All these results indicate that sailboating on vacation, even in a non-professional status, does not promote disease-relevant changes in heart rhythm on trips in mild to moderate seas. Additionally, we were able to demonstrate that the online transfer of electronic data via the Internet from a sailboat offshore is possible, easy and inexpensive.

Adult↗
PubMed2000

Oxygen application by a nasal probe prevents hypoxia but not rebreathing of carbon dioxide in patients undergoing eye surgery under local anaesthesia.

BACKGROUND/AIM: Hypoxia and carbon dioxide rebreathing are potential problems during eye surgery in spontaneously breathing patients. The aim of the present study was to determine effectiveness of nasal application of oxygen to prevent hypoxia and carbon dioxide accumulation in spontaneously breathing patients undergoing cataract surgery. METHODS: Oxygenation and carbon dioxide rebreathing were examined in 40 elderly patients using two different methods of oxygen supply-nasal v ambient air-with a constant flow of 2 l/min. Partial pressure of carbon dioxide under ophthalmic drapes, transcutaneous pressure of carbon dioxide, and the respiratory rate were measured during 25 minutes while oxygen was supplied via a nasal cannula or into the ambient air under the drapes. RESULTS: In both groups carbon dioxide accumulation under the drapes, carbon dioxide rebreathing, tachypnoea, and an increase in peripheral oxygen saturation occurred. No significant differences were found between the two methods. CONCLUSION: Nasal application of oxygen prevented hypoxia but did not prevent carbon dioxide accumulation in patients undergoing eye surgery under retrobulbar anaesthesia. Additionally, as a side effect when using nasal probes, irritation of the nose was described in half of the patients investigated.

Aged↗
PubMed1999

Effect of fluvoxamine on sufentanil antinociception and tolerance under chronic intravenous infusion in rats.

Fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), significantly potentiates analgesia when administered in animals together with opioids. The aim of the present study was to investigate the effects of fluvoxamine on sufentanil antinociception and tolerance. Following animal care committee approval, the effects of continuous infusions of fluvoxamine and sufentanil were studied in behavioural tests (hot-plate test, tail-flick test, catalepsy test) in Sprague-Dawley rats with a jugular vein catheter. Saline was administered as a control. The time-effect curves for continuous intravenous sufentanil indicate dose-related antinociception and rapid development of tolerance in the hot-plate and tail-flick tests. Co-administration of fluvoxamine with continuous sufentanil enhances antinociception and attenuates development of tolerance, most clearly seen in the tail-flick test. Fluvoxamine alone and saline were not effective. No animal showed catalepsy. As a side effect we observed a marked loss of body weight. The IC50 values of sufentanil binding with and without fluvoxamine addition are 0.56+/-0.17 nM and 0.3+/-0.15 nM, respectively, indicating no direct effect on the occupancy of sufentanil on the mu-receptor by this serotonin reuptake inhibitor. In conclusion, we were able to show that the combination of an opioid with an SSRI at low doses improves analgesia and decreases development of tolerance in nociceptive tests in rats. The clinical implications of these promising results in an animal model, however, await further investigation.

Analgesics, Opioid↗
PubMed1998

Patient outcomes with positive pressure versus spontaneous ventilation in non-paralysed adults with the laryngeal mask.

PURPOSE: To compare patient outcomes for positive pressure ventilation (PPV) and spontaneous ventilation (SV) in non-paralysed patients with the LMA using either isoflurane or sevoflurane anaesthesia. METHODS: One hundred and sixty four adult patients were studied. Anaesthesia was with fentanyl/propofol and N2O 66% in O2 with 0.75 MAC isoflurane or sevoflurane and either PPV or SV. Positive pressure ventilation was with tidal volumes of 6-8 ml.kg-1. Peak airway pressures were < 15 cm H2O. Patients were evaluated for airway problems, cardiorespiratory effects, and anaesthesia emergence times. RESULTS: There were no failed episodes of PPV or SV. Gastric insufflation was not detected by epigastric auscultation. Airway problems and cardiovascular effects were similar among groups. During maintenance: SpO2 was greater in the PPV group than in the SV group (98.4 vs 97%, P < 0.001); also, (PETCO2) (34 vs 43 mmHg) and the respiratory rate (RR) (15 vs 19 min-1) were higher and the minute ventilation (MV) (5.7 vs 7.2 L) were lower in the SV groups (P < 0.0001). Shorter times to LMA removal and orientation were observed in the sevoflurane groups (P < 0.0001). CONCLUSIONS: Patient outcome is similar for SV and PPV in non-paralysed adult patients with the LMA. Isoflurane and sevoflurane at 0.75 MAC provide suitable conditions for maintenance and emergence, but emergence is more rapid with sevoflurane.

Adult↗
PubMed1998

Transcutaneous CO2/O2 and CO2/air suction in patients undergoing cataract surgery with retrobulbar anaesthesia.

We investigated transcutaneous partial CO2 and O2 pressures and respiratory rate in unpremedicated elderly patients of ASA physical status 1 to 3 who underwent cataract surgery under retrobulbar anaesthesia. In group A no air suction was used. In group B suction was applied under the sterile drapes to avoid rebreathing of CO2. In group A transcutaneous partial CO2 pressure and respiratory rate significantly increased compared with baseline, whereas in group B they remained constant. In both groups transcutaneous partial O2 pressure and oxygen saturation as measured by pulse oximetry significantly rose after insufflating oxygen 31.min-1. Heart rate and mean arterial blood pressure remained constant. Our results demonstrate that the application of suction near the patient's head prevents CO2 rebreathing and subsequent hypercapnia associated with an elevated respiratory rate. The use of suction makes it unnecessary to raise oxygen administration. Suction combined with monitoring of partial CO2 pressure using transcutaneous sensors should be used in all ophthalmological operations under retrobulbar anaesthesia.

Aged↗
PubMed1998

Cotreatment with racemic fenfluramine inhibits the development of tolerance to morphine analgesia in rats.

As a follow-up study to an earlier report that racemic fenfluramine can acutely potentiate the analgesic effects of morphine in humans, we investigated the effects of fenfluramine on the development of tolerance to morphine analgesia in rats. Antinociceptive effect, as measured by the tail-flick latency, was studied over 8 days in rats that received continuous i.v. infusion of 1) 22 mg/kg/day of morphine, 2) 20 mg/kg/day of fenfluramine, 3) both drugs concomitantly or 4) saline. Infusion with morphine alone resulted in a peak analgesia of 100% maximal possible effect, which declined with time; full tolerance was reached by day 4. Fenfluramine treatment alone had no effect. Fenfluramine coinfusion attenuated the development of tolerance to morphine; >70% maximal possible effect was still present on day 4. The effect of fenfluramine coinfusion occurred in the absence of a significant increase in plasma or brain morphine concentration, or a decrease in the accumulation of morphine's putative antagonistic metabolite, morphine-3-glucuronide. In another set of infusion experiments, rats were challenged with a single i.p. dose of morphine to characterize the morphine dose-response curves at 10 hr following 4-day i.v. infusion of 1) 22 mg/kg/day of morphine, 2) 20 mg/kg/day fenfluramine, 3) morphine plus fenfluramine or 4) saline. An acute i. p. morphine challenge dose response experiment was also conducted in naïve control rats and in rats receiving a concomitant i.p. injection of fenfluramine (2.4 mg/kg). Coinjection of fenfluramine acutely potentiated the antinociceptive potency of morphine. However, potentiation alone does not fully account for the apparent attenuation of tolerance during morphine i.v. infusion. ED50 of morphine was elevated to 7.0 mg/kg in the morphine-infused rats compared to 2.4 mg/kg in saline-infused rats. Coinfusion of fenfluramine increased ED50 to only 3.7 mg/kg. These results demonstrate that fenfluramine significantly attenuates tolerance development to morphine by modulating the pharmacological process responsible for tolerance development to morphine.

Analgesics, Opioid↗
PubMed1997

[Acceptance of an Ethics Committee (International Review Board)].

The work input of an institutional review board, the satisfaction or dissatisfaction of project applicants with its decisions, as well as the amount of time needed for preparatory and follow-up work for projects submitted to the board were surveyed in a questionnaire. An analysis of the status quo provided proposals for improvement, with the aim of increasing the satisfaction of all parties involved. Questionnaires were returned by 41.4% (101/244) of the specialist doctors surveyed. Of these, 42 were doctors who had submitted projects for review and whose evaluation was used for the study. The proportion of trained "clinical review doctors" was 14.3%. Analysis of work input showed that 13.5 +/- 15.2 hours were invested before submitting a project and 6.3 +/- 9.3 hours in the follow-up. Although the board's work was given a satisfactory grading with a score of 2.8 +/- 1.0, the surveyed satisfaction/importance profile showed marked deficits in many areas, primarily in organization and communication, as well as in the examination and evaluation of projects. The suggestions for improvement above all requested the introduction of a review system employing specialists from outside the institution or from other disciplines, standardization of project submission, optimization of organization and improvement in communication. In summary, the institutional review board plays an important role in clinical research. The acceptance of a review board's work, however, can only be improved when the suggestions for improvement are realized step by step. The results of this evaluation and the proposed solutions can also help other boards improve their work. At any rate, it would be desirable to take a new look in several years' time at how the proposals worked out in this study have been implemented.

Austria↗
PubMed1997

Pneumothorax following nasogastric feeding tube insertion in a tracheostomized patient after bilateral lung transplantation.

We report the case of a pneumothorax caused by the improper placement of a nasogastric feeding tube in a tracheostomized patient after bilateral lung transplantation. We discuss the contribution of low-pressure cuffed tracheostomy tubes to the inadvertent respiratory tract misplacement of a nasogastric feeding tube, as well as the problems of nasogastric feeding tube insertion in the sedated patient, why the previously installed closed-tube thoracostomy did not prevent the pneumothorax and possible pitfalls in confirming the proper position of the nasogastric feeding tube. In conclusions, we stress that in high risk patients a nasogastric feeding tube should only be inserted under direct vision and that a subsequent routine X-ray is mandatory for confirming proper positioning.

Humans↗
PubMed1996

Influence of induction technique on intubating conditions after rocuronium in adults: comparison with rapid-sequence induction using thiopentone and suxamethonium.

We have assessed the effect of anaesthetic technique on intubating conditions after rocuronium 0.6 mg kg-1 in four groups (n = 25 each) of unpremedicated patients in whom anaesthesia was induced with either thiopentone 5 mg kg-1 or propofol 2.5 mg kg-1 alone, or supplemented with alfentanil 20 micrograms kg-1. Fifty control patients were anaesthetized with thiopentone followed by suxamethonium. Laryngoscopy was commenced at 45 s. Overall intubating conditions after rocuronium were similar to those after suxamethonium (good and excellent > or = 96%) only when alfentanil was part of the induction regimen. However, intubation time was similar in all five groups and averaged 55 (SD 3.2) s, and the tube could be passed through open vocal cords within 70 s. After rocuronium the response of the diaphragm to intubation was more pronounced in the two groups of patients not receiving alfentanil (P < 0.0001) and in patients anaesthetized using propofol with alfentanil (P < 0.01) than in the control group. Opioids (in doses equivalent to alfentanil 20 micrograms kg-1) constitute an integral part of an induction regimen containing rocuronium 0.6 mg kg-1, regardless of whether or not thiopentone or propofol is used, in order to achieve overall intubating conditions similar to those after suxamethonium.

Adolescent↗
PubMed1996

Comparison of intubating conditions after rocuronium and suxamethonium following "rapid-sequence induction" with thiopentone in elective cases.

BACKGROUND: Rocuronium (Org 9426) was shown to have the fastest onset of action of all currently available non-depolarizing neuromuscular blocking drugs and to provide intubating conditions similar to those of suxamethonium 60 to 90 s after administration. We compared the intubating conditions after rocuronium and suxamethonium following rapid-sequence induction of anaesthesia. METHODS: Fifty unpremedicated patients of ASA physical status I or II, scheduled for elective surgery were studied. Anaesthesia was induced with thiopentone 6 mg kg-1 followed randomly by suxamethonium 1 mg kg-1 or rocuronium 0.6 mg kg-1 and, 45 s later, intubation was commenced. Muscle fasciculations, intubating conditions and intubation time, haemodynamic variables and oxygenation were assessed. RESULTS: Intubation time did not differ between suxamethonium (9.8 +/- 2.2 s) (mean +/- SD) and rocuronium (10.5 +/- 2.9 s), respectively. Intubating conditions were clinically acceptable (good or excellent) in all patients given suxamethonium and in 96% of the patients given rocuronium. However, the condition of the vocal cords was better (P < 0.05) and diaphragmatic response to intubation was less pronounced with suxamethonium (P < 0.05). Changes in heart rate and arterial blood pressure were similar in both groups. CONCLUSION: The authors conclude that rocuronium is a suitable alternative to suxamethonium for rapid tracheal intubation even under unsupplemented thiopentone anaesthesia, at least in elective, otherwise healthy patients. Its use for rapid-sequence induction under emergency conditions, however, needs further investigation.

Adolescent↗