Publications by authors named "Riku Aantaa"

36 Publications

Information needs in day-to-day operations management in hospital units: A cross-sectional national survey.

J Nurs Manag 2019 Mar 9;27(2):233-244. Epub 2018 Oct 9.

Department of Nursing Science, University of Turku and Turku University Hospital, Turku, Finland.

Aim: To describe and compare shift leaders' important information needs by profession, unit, time of day and type of hospital.

Background: Professionals responsible for care provision in hospital units make ad hoc decisions about available resources to meet patient care needs but, currently, much effort is needed to obtain the necessary information to support decision making.

Methods: This survey was carried out in nine randomly chosen hospitals in Finland. Nurses and physicians responsible for day-to-day operations were eligible to participate (N = 873). The response rate was 65% (n = 570, including 453 nurses and 111 physicians). Data were collected in 2015-2016 using the Hospital Shift Leaders' Information Needs Questionnaire with 114 information need items.

Results: Shift leaders reported many real-time information needs. Nurses' important information needs concerned patients, personnel, and materials, and physicians' needs focused on patient care. Large mean differences existed in the needs between nurses and physicians, and imaging units when compared to other units.

Conclusion: Real-time information systems for shift leaders should consider the needs of different users to support shared situational awareness and operational intelligence.

Implications For Nursing Management: The important information-need items identified here may be used in designing and developing information systems that better support shift leaders' work in hospitals.
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http://dx.doi.org/10.1111/jonm.12700DOI Listing
March 2019

Acute pain intensity monitoring with the classification of multiple physiological parameters.

J Clin Monit Comput 2019 Jun 26;33(3):493-507. Epub 2018 Jun 26.

Department of Future Technologies, University of Turku, Turku, Finland.

Current acute pain intensity assessment tools are mainly based on self-reporting by patients, which is impractical for non-communicative, sedated or critically ill patients. In previous studies, various physiological signals have been observed qualitatively as a potential pain intensity index. On the basis of that, this study aims at developing a continuous pain monitoring method with the classification of multiple physiological parameters. Heart rate (HR), breath rate (BR), galvanic skin response (GSR) and facial surface electromyogram were collected from 30 healthy volunteers under thermal and electrical pain stimuli. The collected samples were labelled as no pain, mild pain or moderate/severe pain based on a self-reported visual analogue scale. The patterns of these three classes were first observed from the distribution of the 13 processed physiological parameters. Then, artificial neural network classifiers were trained, validated and tested with the physiological parameters. The average classification accuracy was 70.6%. The same method was applied to the medians of each class in each test and accuracy was improved to 83.3%. With facial electromyogram, the adaptivity of this method to a new subject was improved as the recognition accuracy of moderate/severe pain in leave-one-subject-out cross-validation was promoted from 74.9 ± 21.0 to 76.3 ± 18.1%. Among healthy volunteers, GSR, HR and BR were better correlated to pain intensity variations than facial muscle activities. The classification of multiple accessible physiological parameters can potentially provide a way to differentiate among no, mild and moderate/severe acute experimental pain.
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http://dx.doi.org/10.1007/s10877-018-0174-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6499869PMC
June 2019

Assessing managerial information needs: Modification and evaluation of the Hospital Shift Leaders' Information Needs Questionnaire.

J Nurs Manag 2018 Mar 30;26(2):108-119. Epub 2018 Jan 30.

Department of Nursing Science, University of Turku and Turku University Hospital, Turku, Finland.

Aims: The aims were (1) to evaluate the modified version of the Intensive Care Unit Information Need Questionnaire for the broader hospital setting, and (2) to describe the differences in respondents' managerial activities and information needs according to the position held by the respondent and the type of hospital unit.

Background: Information systems do not support managerial decision-making sufficiently and information needed in the day-to-day operations management in hospital units is unknown.

Methods: An existing questionnaire was modified and evaluated. Shift leaders, that is, the nurses and physicians responsible for the day-to-day operations management in hospital units were reached using purposive sampling (n = 258).

Results: The questionnaire ascertained the importance of information. Cronbach's α ranged from .85-.96 for the subscales. Item - total correlations showed good explanatory power. Managerial activities and information needs differed between respondents in different positions, although all shared about one-third of important information needs. The response rate was 26% (n = 67).

Conclusions: The validity and reliability of the questionnaire were good. Attention should be paid to the positions of shift leaders when developing information systems.

Implications For Nursing Management: The questionnaire can be used to determine important information when developing information systems to support day-to-day operations management in hospitals.
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http://dx.doi.org/10.1111/jonm.12515DOI Listing
March 2018

Prevalence of life-supporting prolonged invasive ventilation support in Finland.

Duodecim 2017;133(7):675-82

Background: There is no comprehensive data in our country on the prevalence of life-supporting prolonged invasive ventilation support. The objective of the survey was to clarify in all hospital districts of continental Finland the prevalence of patients who were dependent on invasive ventilation support, and the disease leading to the treatment.

Patients And Methods: The KOTIVEHNO 2015 survey was carried out as population-based cross-sectional study by sending a questionnaire to all doctors in charge of prolonged invasive ventilation support. The questionnaires were used to collect data on the patients within care on 1st January, 2017.

Results: The prevalence of life-supporting prolonged invasive ventilation support in Finland among the population aged over 16 years or more was 2/4 patients/100,000 habitants. Altogether 107 patients were within the care. There was variation in the prevalence among the hospital districts. Of the patients, 24% were affected with a motoneuron disease, in 18% the cause was spinal cord injury, 15% suffered from Duchenne's muscular dystrophy, and the rest had some other rare neurological disease.

Conclusions: Life-supporting prolonged invasive ventilation support is rare in Finland. The treatment is associated with neuromuscular diseases causing respiratory insufficiency, and with spinal cord injuries.
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January 2018

A multinational, drug utilization study to investigate the use of dexmedetomidine (Dexdor®) in clinical practice in the EU.

Br J Clin Pharmacol 2017 Sep 10;83(9):2066-2076. Epub 2017 May 10.

RTI Health Solutions, Av. Diagonal 605, 9-1, 08028, Barcelona, Spain.

Aims: Dexmedetomidine (dexdor®) is approved in the European Union (EU) for sedation of adults in the intensive care unit (ICU). The present observational, retrospective study was requested by the European Medicines Agency to investigate dexmedetomidine use in clinical practice, with a particular focus on off-label use, including the paediatric population.

Methods: Study countries and sites were chosen from those with highest dexmedetomidine use, based on sales. Site selection (blind) was conducted by a multispecialist, independent group. Anonymized data on demographics, treatment indication, dexmedetomidine dosing, concomitant medications and treatment effectiveness were collected retrospectively from records of all dexmedetomidine-treated patients at the site during the enrolment period. Informed consent was waived, to avoid influencing the prescribing of dexmedetomidine. Recruitment was completed within 18 months of first site initiation.

Results: Data from 2000 patients were collected from 16 hospitals in four EU countries (Finland 750, Poland 505, Germany 470, Austria 275). The median age was 62 years, with more males (70.2%) than females. Dexmedetomidine was primarily used in the adult ICU (86.0%) for ICU sedation (78.6%) and mostly dosed according the product label. The intended sedative effect was obtained in 84.9% of administrations. Paediatric use (5.9% of patients, mostly in Austria and Finland) occurred mainly in the adult or paediatric ICU (75.6%) for sedation (67.2%).

Conclusions: Overall, most patients were treated with dexmedetomidine according to the product labelling. Use in children was limited but significant and similar in scope to that in adults. Administrations not fully according to the product labelling usually occurred in an ICU environment and reflected extensively investigated clinical uses of dexmedetomidine.
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http://dx.doi.org/10.1111/bcp.13293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555873PMC
September 2017

The Internet of Things for basic nursing care-A scoping review.

Int J Nurs Stud 2017 Apr 1;69:78-90. Epub 2017 Feb 1.

Department of Nursing Science, University of Turku, FI-20014 Turun Yliopisto, Finland; Turku University Hospital, 20521, Turku, Finland.

Background: The novel technology of the Internet of Things (IoT) connects objects to the Internet and its most advanced applications refine obtained data for the user. We propose that Internet of Things technology can be used to promote basic nursing care in the hospital environment by improving the quality of care and patient safety.

Objectives: To introduce the concept of Internet of Things to nursing audience by exploring the state of the art of Internet of Things based technology for basic nursing care in the hospital environment.

Data Sources And Review Methods: Scoping review methodology following Arksey & O'Malley's stages from one to five were used to explore the extent, range, and nature of current literature. We searched eight databases using predefined search terms. A total of 5030 retrievals were found which were screened for duplications and relevancy to the study topic. 265 papers were chosen for closer screening of the abstracts and 93 for full text evaluation. 62 papers were selected for the review. The constructs of the papers, the Internet of Things based innovations and the themes of basic nursing care in hospital environment were identified.

Results: Most of the papers included in the review were peer-reviewed proceedings of technological conferences or articles published in technological journals. The Internet of Things based innovations were presented in methodology papers or tested in case studies and usability assessments. Innovations were identified in several topics in four basic nursing care activities: comprehensive assessment, periodical clinical reassessment, activities of daily living and care management.

Conclusions: Internet of Things technology is providing innovations for the use of basic nursing care although the innovations are emerging and still in early stages. Internet of things is yet vaguely adopted in nursing. The possibilities of the Internet of Things are not yet exploited as well as they could. Nursing science might benefit from deeper involvement in engineering research in the area of health.
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http://dx.doi.org/10.1016/j.ijnurstu.2017.01.009DOI Listing
April 2017

[Supraventricular tachycardia during pregnancy].

Duodecim 2016 ;132(2):173-5

An increase in cardiac output during pregnancy increases the risk of arrhythmias for the expectant mother. Supraventricular tachycardia (SVT) underlies the sensations of arrhythmia in a pregnant woman in as many as one sixth of the cases. Vagal nerve (n. vagus) stimulation and adenosine serve as first-line treatment, but electrical cardioversion is likely to be a safe alternative as well. We describe a case in which the SVT of a woman in the third trimester of pregnancy was unresponsive to vagal nerve stimulation and pharmacological treatments. Electrical cardioversion was successfully performed after having a cesarean section procedure.
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April 2016

[Amyotrophic lateral sclerosis and respiratory insufficiency].

Duodecim 2015 ;131(2):127-35

Amyotrophic lateral sclerosis (ALS) is a disease causing degeneration of motor neurons, without any curative treatment. The most common cause of death is respiratory arrest due to atrophy of the respiratory musculature. ALS-associated respiratory insufficiency differs in mechanism from the more common causes of dyspnea, such as diseases of pulmonary or cardiac origin. Recognizing the respiratory insufficiency can be challenging for a clinician. It should be possible to predict the development of respiratory insufficiency in order to avoid leaving the treatment decisions concerning respiratory insufficiency to emergency services. Noninvasive ventilatory support can be used to alleviate the patient's dyspnea. It is actually recommended as the first-line treatment of ALS-associated respiratory insufficiency.
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August 2015

Mechanism-based population pharmacokinetic and pharmacodynamic modeling of intravenous and intranasal dexmedetomidine in healthy subjects.

Eur J Clin Pharmacol 2015 Oct 2;71(10):1197-207. Epub 2015 Aug 2.

Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, 404 Kapoor Hall, State University of New York at Buffalo, Buffalo, NY, 14214, USA.

Purpose: Dexmedetomidine is an α2-adrenoceptor agonist used for perioperative and intensive care sedation. This study develops mechanism-based population pharmacokinetic-pharmacodynamic models for the cardiovascular and central nervous system (CNS) effects of intravenously (IV) and intranasally (IN) administered dexmedetomidine in healthy subjects.

Method: Single doses of 84 μg of dexmedetomidine were given once IV and once IN to six healthy men. Plasma dexmedetomidine concentrations were measured for 10 h along with plasma concentrations of norepinephrine (NE) and epinephrine (E). Blood pressure, heart rate, and CNS drug effects (three visual analog scales and bispectral index) were monitored to assess the pharmacological effects of dexmedetomidine. PK-PD modeling was performed for recently published data (Eur J Clin Pharmacol 67: 825, 2011).

Results: Pharmacokinetic profiles for both IV and IN doses of dexmedetomidine were well fitted using a two-compartment PK model. Intranasal bioavailability was 82%. Dexmedetomidine inhibited the release of NE and E to induce their decline in blood. This decrease in NE was captured with an indirect response model. The concentrations of the mediator NE served via a biophase/transduction step and nonlinear pharmacologic functions to produce reductions in blood pressure and heart rate, while a direct effect model was used for the CNS effects.

Conclusion: The comprehensive panel of two biomarkers and seven response measures were well captured by the population PK/PD models. The subjects were more sensitive to the CNS (lower EC 50 values) than cardiovascular effects of dexmedetomidine.
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http://dx.doi.org/10.1007/s00228-015-1913-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7167593PMC
October 2015

Sedation options for the morbidly obese intensive care unit patient: a concise survey and an agenda for development.

Multidiscip Respir Med 2015 7;10(1). Epub 2015 Mar 7.

Department of Anaesthesiology, Intensive and Emergency Care, Sint Jan Brugge-Oostende, Ruddershove 10, Brugge, 8000 Belgium.

Background: We offer some perspectives and commentary on the sedation of obese patients in the intensive care unit (ICU).

Discussion: Sedation in morbidly obese patients should conform to the same broad principles now current in ICU practice. These include a general presumption against benzodiazepines as first-line agents. Opioids should be avoided in any situation where spontaneous breathing is required. Remifentanil is the preferred agent where continuous stable opioid levels using an infusion are required, because of its lack of context-sensitive accumulation. Volatile anaesthetics may be an option for the same reason but there are no substantial, controlled demonstrations of effectiveness/safety in short-term use in the ICU setting. Propofol is a valuable resource in the morbidly obese patients but the duration of continuous sedation should not exceed 6 days, in order to avoid propofol infusion syndrome. Alpha-2 agonists offer a range of theoretically positive features for the sedation of morbidly obese patients, but at present there is a lack of pharmacokinetic data and a critical mass of high-grade clinical data. Dexmedetomidine has the attraction of not causing respiratory depression or obstructive breathing during sedation and its sympatholytic effects should help deliver stable blood pressure and heart rate. Ketamine has a poor tolerability profile in adults so its use in the ICU context is largely confined to paediatrics.

Conclusion: None of the agents currently available is ideal for every situation encountered in the management of morbidly obese patients. This article identifies additional research needed to place sedation practice of obese patients on a more systematic footing.
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http://dx.doi.org/10.1186/s40248-015-0007-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4399437PMC
April 2015

Sedation in non-invasive ventilation: do we know what to do (and why)?

Multidiscip Respir Med 2014 4;9(1):56. Epub 2014 Nov 4.

Department of Anesthesiology and Intensive Care Medicine, Emergency Medicine Hospital Links der Weser GmbH, Bremen, Germany.

This review examines some of the issues encountered in the use of sedation in patients receiving respiratory support from non-invasive ventilation (NIV). This is an area of critical and intensive care medicine where there are limited (if any) robust data to guide the development of best practice and where local custom appears to exert a strong influence on patterns of care. We examine aspects of sedation for NIV where the current lack of structure may be contributing to missed opportunities to improve standards of care and examine the existing sedative armamentarium. No single sedative agent is currently available that fulfils the criteria for an ideal agent but we offer some observations on the relative merits of different agents as they relate to considerations such as effects on respiratory drive and timing, and airways patency. The significance of agitation and delirium and the affective aspect(s) of dyspnoea are also considered. We outline an agenda for placing the use of sedation in NIV on a more systematic footing, including clearly expressed criteria and conditions for terminating NIV and structural and organizational conditions for prospective multicentre trials.
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http://dx.doi.org/10.1186/2049-6958-9-56DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4333891PMC
February 2015

Translation and cultural adaptation of an objective pain assessment tool for Finnish ICU patients.

Scand J Caring Sci 2014 Dec 4;28(4):885-94. Epub 2013 Dec 4.

Department of Nursing Science, University of Turku, Turku, Finland.

Aim: The purpose of this study was to culturally validate three pain measurement instruments [Behavioral Pain Scale (BPS), the Critical-Care Pain Observation Tool (CPOT) and the Nonverbal Adult Pain Assessment Scale (NVPS)] for sedated intensive care patients and in doing so to prepare the tools for psychometric testing in the Finnish intensive care environment.

Background: Most patients feel pain during their stay in an intensive care unit. Pain recognition and assessment is the first step towards effective pain management. The BPS, CPOT and NVPS are the most valid and reliable pain assessment instruments developed to objectively assess pain in sedated intensive care patients.

Method: The translation and cultural adaptation of the instruments were done according to the guidelines of the International Society for Pharmacoeconomics and Outcomes (ISPOR). The process included 10 phases aiming to produce semantically correct Finnish versions of the pain assessment instruments. This translation process was chosen due to its rigorousness and systematic approach.

Results: The 10-step translation and cultural validation process were successfully conducted, although it was complex and time-consuming. The resulting Finnish versions of the three pain assessment instruments showed good evidence of content and conceptual equivalence. Although further work is needed to test these instruments in the Finnish intensive care context, the current Finnish versions are potential instruments for clinicians to use.

Conclusion: Deciding when this high-quality process is needed requires thorough consideration. However, it is worthwhile to use it when implementing new instruments at a national level. We need a valid, reliable and feasible instrument for pain assessment in sedated intensive care patients in Finland. The next step in our process is conducting psychometric testing of these three instruments to choose the tool with the best properties to be implemented in clinical practice.
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http://dx.doi.org/10.1111/scs.12103DOI Listing
December 2014

Postoperative fentanyl patch versus subacromial bupivacaine infusion in arthroscopic shoulder surgery.

Arthroscopy 2013 Jul;29(7):1129-34

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital and University, Turku, Finland.

Purpose: The purpose of our study was to compare the effectiveness of subacromial bupivacaine infusion and a transdermal fentanyl patch in the treatment of postoperative pain after arthroscopic shoulder surgery.

Methods: Sixty patients with rotator cuff disease scheduled for elective arthroscopic shoulder surgery were enrolled in the study. For the treatment of postoperative pain, 30 patients constituted group F and received a 12.0-μg/h fentanyl patch for 72 hours and saline solution infusion in a subacromial manner at the rate of 4 mL/h. The remaining 30 patients constituted group B and received a placebo patch and an infusion of 2.5-mg/mL bupivacaine in a subacromial manner for 72 hours. The primary outcome measure was the postoperative numerical rating scale pain score. The consumption of opioids, ibuprofen, and acetaminophen was also recorded. The Constant scores and general recovery were followed up until the 90th postoperative day.

Results: There was no statistically significant difference in the numerical rating scale scores (P = .60) between the groups. No differences in the use of rescue analgesic were observed except that the patients receiving bupivacaine used more ibuprofen (median, 1,200 mg v 600 mg) during the day of surgery (P = .042). No difference was found in general recovery between the groups.

Conclusions: A fentanyl patch delivering 12-μg/h fentanyl offers an easy and safe treatment option as a part of multimodal analgesia with few adverse effects in the treatment of postoperative pain in a carefully selected patient group after arthroscopic shoulder surgery.

Level Of Evidence: Level I, randomized controlled trial.
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http://dx.doi.org/10.1016/j.arthro.2013.04.018DOI Listing
July 2013

Is the effect of non-invasive ventilation on survival in amyotrophic lateral sclerosis age-dependent?

BMC Palliat Care 2013 24;12:23. Epub 2013 May 24.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital and University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku 52, Finland.

Background: Hypoventilation due to respiratory muscle atrophy is the most common cause of death as a result of amyotrophic lateral sclerosis (ALS). Patients aged over 65 years and presenting bulbar symptoms are likely to have a poorer prognosis. The aim of the study was to assess the possible impact of age and treatment with non-invasive ventilation (NIV) on survival in ALS. Based on evidence from earlier studies, it was hypothesized that NIV increases rates of survival regardless of age.

Methods: Eighty-four patients diagnosed with ALS were followed up on from January 2001 to June 2012. These patients were retrospectively divided into two groups according to their age at the time of diagnosis: Group 1 comprised patients aged ≤ 65 years while Group 2 comprised those aged > 65 years. Each group included 42 patients. NIV was tolerated by 23 patients in Group 1 and 18 patients in Group 2. Survival was measured in months from the date of diagnosis.

Results: The median age in Group 1 was 59 years (range 49 - 65) and 76 years in Group 2 (range 66 - 85). Among patients in Group 1 there was no difference in probability of survival between the NIV users and non-users (Hazard Ratio = 0.88, 95% CI 0.44 - 1.77, p = 0.7). NIV users in Group 2 survived longer than those following conventional treatment (Hazard Ratio = 0.25, CI 95% 0.11 - 0.55, p <0.001). ALS patients in Group 2 who did not use NIV had a 4-fold higher risk for death compared with NIV users.

Conclusions: This retrospective study found that NIV use was associated with improved survival outcomes in ALS patients older than 65 years. Further studies in larger patient populations are warranted to determine which factors modify survival outcomes in ALS.
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http://dx.doi.org/10.1186/1472-684X-12-23DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698107PMC
May 2014

Using respiratory rate and thoracic movement to assess respiratory insufficiency in amyotrophic lateral sclerosis: a preliminary study.

BMC Palliat Care 2012 Dec 27;11:26. Epub 2012 Dec 27.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital and University of Turku, Turku, Finland.

Unlabelled:

Background: Hypoventilation due to respiratory insufficiency is the most common cause of death in amyotrophic lateral sclerosis (ALS) and non-invasive ventilation (NIV) can be used as a palliative treatment. The current guidelines recommend performing spirometry, and recording nocturnal oxyhemoglobin saturation and arterial blood gas analysis to assess the severity of the hypoventilation. We examined whether the respiratory rate and thoracic movement were reliable preliminary clinical signs in the development of respiratory insufficiency in patients with ALS.

Methods: We measured the respiratory rate and thoracic movement, performed respiratory function tests and blood gas analysis, and recorded subjective hypoventilation symptoms in 42 ALS patients over a 7-year period. We recommended NIV if the patient presented with hypoventilation matching the current guidelines. We divided patients retrospectively into two groups: those to whom NIV was recommended within 6 months of the diagnosis (Group 1) and those to whom NIV was recommended 6 months after the diagnosis (Group 2). We used the Mann Whitney U test for comparisons between the two groups.

Results: The mean partial pressure of arterial carbon dioxide in the morning in Group 1 was 6.3 (95% confidence interval 5.6-6.9) kPa and in Group 2 5.3 (5.0-5.6) kPa (p = 0.007). The mean respiratory rate at the time of diagnosis in Group 1 was 21 (18-24) breaths per minute and 16 (14-18) breaths per minute in Group 2 (p = 0.005). The mean thoracic movement was 2.9 (2.2-3.6) cm in Group 1 and 4.0 (3.4-4.8) cm in Group 2 (p = 0.01). We observed no other differences between the groups.

Conclusions: Patients who received NIV within six months of the diagnosis of ALS had higher respiratory rates and smaller thoracic movement compared with patients who received NIV later. Further studies with larger numbers of patients are needed to establish if these measurements can be used as a marker of hypoventilation in ALS.
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http://dx.doi.org/10.1186/1472-684X-11-26DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3544688PMC
December 2012

Returning from oblivion: imaging the neural core of consciousness.

J Neurosci 2012 Apr;32(14):4935-43

Turku PET Centre, University of Turku and Turku University Hospital, FI-20521 Turku, Finland.

One of the greatest challenges of modern neuroscience is to discover the neural mechanisms of consciousness and to explain how they produce the conscious state. We sought the underlying neural substrate of human consciousness by manipulating the level of consciousness in volunteers with anesthetic agents and visualizing the resultant changes in brain activity using regional cerebral blood flow imaging with positron emission tomography. Study design and methodology were chosen to dissociate the state-related changes in consciousness from the effects of the anesthetic drugs. We found the emergence of consciousness, as assessed with a motor response to a spoken command, to be associated with the activation of a core network involving subcortical and limbic regions that become functionally coupled with parts of frontal and inferior parietal cortices upon awakening from unconsciousness. The neural core of consciousness thus involves forebrain arousal acting to link motor intentions originating in posterior sensory integration regions with motor action control arising in more anterior brain regions. These findings reveal the clearest picture yet of the minimal neural correlates required for a conscious state to emerge.
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http://dx.doi.org/10.1523/JNEUROSCI.4962-11.2012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6620928PMC
April 2012

Validation of indirect calorimetry for measurement of energy expenditure in healthy volunteers undergoing pressure controlled non-invasive ventilation support.

J Clin Monit Comput 2012 Feb 30;26(1):37-43. Epub 2011 Dec 30.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital and University of Turku, Kiinamyllynkatu 4-8, 20521, Turku, Finland.

The aim of this validation study was to assess the reliability of gas exchange measurement with indirect calorimetry among subjects who undergo non-invasive ventilation (NIV). Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured in twelve healthy volunteers. Respiratory quotient (RQ) and resting energy expenditure (REE) were then calculated from the measured VO2 and VCO2 values. During the measurement period the subjects were breathing spontaneously and ventilated using NIV. Two different sampling air flow values 40 and 80 l/min were used. The gas leakage from the measurement setup was assessed with a separate capnograph. The mean weight of the subjects was 93 kg. Their mean body mass index was 29 (range 22-40) kg/m2. There was no statistically significant difference in the measured values for VO2, VCO2, RQ and REE during NIV-supported breathing and spontaneous breathing. The change of sampling air flow had no statistically significant effect on any of the above parameters. We found that REE can be accurately measured with an indirect calorimeter also during NIV-supported breathing and the change of sampling air flow does not distort the gas exchange measurement. A higher sampling air flow in indirect calorimetry decreases the possibility for air leakages in the measurement system and increases the reliability of REE measurement.
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http://dx.doi.org/10.1007/s10877-011-9331-zDOI Listing
February 2012

Pharmacokinetics of prolonged infusion of high-dose dexmedetomidine in critically ill patients.

Crit Care 2011 26;15(5):R257. Epub 2011 Oct 26.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, University of Turku and Turku University Hospital, PO Box 52, FI-20521 Turku, Finland.

Introduction: Only limited information exists on the pharmacokinetics of prolonged (> 24 hours) and high-dose dexmedetomidine infusions in critically ill patients. The aim of this study was to characterize the pharmacokinetics of long dexmedetomidine infusions and to assess the dose linearity of high doses. Additionally, we wanted to quantify for the first time in humans the concentrations of H-3, a practically inactive metabolite of dexmedetomidine.

Methods: Thirteen intensive care patients with mean age of 57 years and Simplified Acute Physiology Score (SAPS) II score of 45 were included in the study. Dexmedetomidine infusion was commenced by using a constant infusion rate for the first 12 hours. After the first 12 hours, the infusion rate of dexmedetomidine was titrated between 0.1 and 2.5 μg/kg/h by using predefined dose levels to maintain sedation in the range of 0 to -3 on the Richmond Agitation-Sedation Scale. Dexmedetomidine was continued as long as required to a maximum of 14 days. Plasma dexmedetomidine and H-3 metabolite concentrations were measured, and pharmacokinetic variables were calculated with standard noncompartmental methods. Safety and tolerability were assessed by adverse events, cardiovascular signs, and laboratory tests.

Results: The following geometric mean values (coefficient of variation) were calculated: length of infusion, 92 hours (117%); dexmedetomidine clearance, 39.7 L/h (41%); elimination half-life, 3.7 hours (38%); and volume of distribution during the elimination phase, 223 L (35%). Altogether, 116 steady-state concentrations were found in 12 subjects. The geometric mean value for clearance at steady state was 53.1 L/h (55%). A statistically significant linear relation (r2 = 0.95; P < 0.001) was found between the areas under the dexmedetomidine plasma concentration-time curves and cumulative doses of dexmedetomidine. The elimination half-life of H-3 was 9.1 hours (37%). The ratio of AUC0-∞ of H-3 metabolite to that of dexmedetomidine was 1.47 (105%), ranging from 0.29 to 4.4. The ratio was not statistically significantly related to the total dose of dexmedetomidine or the duration of the infusion.

Conclusions: The results suggest linear pharmacokinetics of dexmedetomidine up to the dose of 2.5 μg/kg/h. Despite the high dose and prolonged infusions, safety findings were as expected for dexmedetomidine and the patient population.

Trial Registration: ClinicalTrials.gov: NCT00747721.
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http://dx.doi.org/10.1186/cc10518DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3334808PMC
August 2012

Consciousness lost and found: subjective experiences in an unresponsive state.

Brain Cogn 2011 Dec 8;77(3):327-34. Epub 2011 Oct 8.

Centre for Cognitive Neuroscience, Department of Psychology, University of Turku, 20014 Turku, Finland.

Anesthetic-induced changes in the neural activity of the brain have been recently utilized as a research model to investigate the neural mechanisms of phenomenal consciousness. However, the anesthesiologic definition of consciousness as "responsiveness to the environment" seems to sidestep the possibility that an unresponsive individual may have subjective experiences. The aim of the present study was to analyze subjective reports in sessions where sedation and the loss of responsiveness were induced by dexmedetomidine, propofol, sevoflurane or xenon in a nonsurgical experimental setting. After regaining responsiveness, participants recalled subjective experiences in almost 60% of sessions. During dexmedetomidine sessions, subjective experiences were associated with shallower "depth of sedation" as measured by an electroencephalography-derived anesthesia depth monitor. Results confirm that subjective experiences may occur during clinically defined unresponsiveness, and that studies aiming to investigate phenomenal consciousness under sedative and anesthetic effects should control the subjective state of unresponsive participants with post-recovery interviews.
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http://dx.doi.org/10.1016/j.bandc.2011.09.002DOI Listing
December 2011

Renal effects of dexmedetomidine during coronary artery bypass surgery: a randomized placebo-controlled study.

BMC Anesthesiol 2011 May 23;11. Epub 2011 May 23.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital, Turku, Finland.

Background: Dexmedetomidine, an alpha₂-adrenoceptor agonist, has been evaluated as an adjunct to anesthesia and for the delivery of sedation and perioperative hemodynamic stability. It provokes dose-dependent and centrally-mediated sympatholysis. Coronary artery bypass grafting (CABG) with extracorporeal circulation is a stressful procedure increasing sympathetic nervous system activity which could attenuate renal function due the interrelation of sympathetic nervous system, hemodynamics and renal function. We tested the hypothesis that dexmetomidine would improve kidney function in patients undergoing elective CABG during the first two postoperative days.

Methods: This was a double-blind, randomized, parallel-group study. Patients with normal renal function and scheduled for elective CABG were randomized to placebo or to infusion of dexmedetomidine to achieve a pseudo steady-state plasma concentration of 0.60 ng/ml. The infusion was started after anesthesia induction and continued until 4 h after surgery. The primary endpoint was creatinine clearance. Other variables included urinary creatinine and output, fractional sodium and potassium excretion, urinary potassium, sodium and glucose, serum and urinary osmolality and plasma catecholamine concentrations. The data were analyzed with repeated-measures ANOVA or Cochran-Mantel-Haenszel test.

Results: Sixty-six of 87 randomized patients were evaluable for analysis. No significant between-group differences were recorded for any indices of renal function except for a mean 74% increase in urinary output with dexmedetomidine in the first 4 h after insertion of a urinary catheter (p < 0.001). Confidence interval examination revealed that the sample size was large enough for the no-difference statement for creatinine clearance.

Conclusions: Use of intravenous dexmedetomidine did not alter renal function in this cohort of relatively low-risk elective CABG patients but was associated with an increase in urinary output.This study was carried out in 1994-1997 and was thus not registered.
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http://dx.doi.org/10.1186/1471-2253-11-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3123640PMC
May 2011

Bioavailability of dexmedetomidine after intranasal administration.

Eur J Clin Pharmacol 2011 Aug 12;67(8):825-31. Epub 2011 Feb 12.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, University of Turku and Turku University Hospital, P.O. Box 52, FI-20521, Turku, Finland.

Purpose: The aim of this proof-of-concept study was to characterize the pharmacokinetics and pharmacodynamics of intranasal dexmedetomidine compared with its intravenous administration in a small number of healthy volunteers.

Methods: Single doses of 84 μg of dexmedetomidine were given once intravenously and once intranasally to seven healthy men. Plasma dexmedetomidine concentrations were measured for 10 h, and pharmacokinetic variables were calculated with standard noncompartmental methods. Heart rate, blood pressure, concentrations of adrenaline and noradrenaline in plasma, and central nervous system drug effects (with the Maddox wing, Bispectral Index, and three visual analog scales) were monitored to assess the pharmacological effects of dexmedetomidine.

Results: Six individuals were included in the analyses. Following intranasal administration, peak plasma concentrations of dexmedetomidine were reached in 38 (15-60) min and its absolute bioavailability was 65% (35-93%) (medians and ranges). Pharmacological effects were similar with both routes of administration, but their onset was more rapid after intravenous administration.

Conclusions: Dexmedetomidine is rather rapidly and efficiently absorbed after intranasal administration. Compared with intravenous administration, intranasal administration may be a feasible alternative in patients requiring light sedation.
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http://dx.doi.org/10.1007/s00228-011-1002-yDOI Listing
August 2011

Pharmacokinetics of intravenous paracetamol in elderly patients.

Clin Pharmacokinet 2011 Feb;50(2):121-9

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, University of Turku and Turku University Hospital, Turku, Finland.

Background And Objectives: Intravenous paracetamol (N-acetyl-paraminophenol, acetaminophen) is a widely used nonopioid analgesic which has become popular in the treatment of pain in many patient groups, including the elderly. Although intravenous paracetamol has been studied widely in clinical analgesia studies, there is little information on its pharmacokinetics in the elderly. We designed this study to determine the pharmacokinetics of intravenous paracetamol in very old patients and to compare them with that of younger patients. We also considered the effect of adenosine triphosphate-binding cassette G2 protein (ABCG2) genotype and renal function on paracetamol pharmacokinetics in these patients.

Methods: We compared the pharmacokinetics of intravenous paracetamol in four groups of ten patients, aged 20-40, 60-70, 70-80 and 80-90 years, undergoing orthopaedic surgery. Paracetamol 1000 mg was given by infusion over 15 minutes. Plasma concentrations of paracetamol and its glucuronide and sulphate conjugates were measured for 24 hours with a high-performance liquid chromatographic method and ABCG2 genotype was determined. Glomerular filtration rate (GFR) was estimated from age, sex and serum creatinine of the patient.

Results: In the group aged 80-90 years, the mean value of the area under the plasma concentration-time curve extrapolated to infinity (AUC(∞)) of paracetamol was 54-68% higher than in the two youngest groups. Paracetamol clearance showed a statistically significant dependence on age group, whereas volume of distribution during elimination and elimination half-life were associated with age group and sex, respectively. Based on mean AUC(∞) of paracetamol glucuronide and paracetamol sulphate, the oldest patients had 1.3- to 1.5-fold greater exposure to these metabolites than patients aged 20-40 years. ABCG2 genotype did not affect paracetamol pharmacokinetics. There was a linear correlation between the values of AUC(∞) of paracetamol, its glucuronide and sulphate metabolites and GFR.

Conclusion: Age and sex are important factors affecting the pharmacokinetics of paracetamol. The higher the age of the patient, the higher is the exposure to paracetamol. Female sex is associated with increased paracetamol concentrations but ABCG2 genotype does not seem to affect paracetamol pharmacokinetics. Trial registration number (EudraCT): 2006-001917-14.
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http://dx.doi.org/10.2165/11537240-000000000-00000DOI Listing
February 2011

Elimination of intravenous oxycodone in the elderly: a pharmacokinetic study in postoperative orthopaedic patients of different age groups.

Drugs Aging 2011 Jan;28(1):41-50

Department of Anesthesiology, Intensive Care, Emergency Care and Pain Medicine, University of Turku and Turku University Hospital, Turku, Finland.

Background And Objective: Oxycodone is a widely used opioid analgesic, the global use of which has increased several-fold during the last decade. This study was designed to determine the effect of age on the pharmacokinetics of intravenous oxycodone, with special reference to renal function in elderly patients.

Methods: We compared the pharmacokinetics of 5 mg of intravenous oxycodone in four groups of 10-11 patients, aged 20-40, 60-70, 70-90 years, undergoing orthopaedic surgery. Plasma concentrations of oxycodone and its noroxycodone, oxymorphone and noroxymorphone metabolites were measured for 24 hours with a liquid chromatography-tandem mass spectrometric method. The cytochrome P450 (CYP) 2D6 genotype of the patients was determined. Glomerular filtration rate (GFR) was estimated on the basis of the age, sex and serum creatinine concentration of the patient.

Results: The pharmacokinetics of oxycodone showed age dependency. In the oldest group, the mean area under the plasma concentration-time curve from time zero to infinity (AUC(∞)) of oxycodone was 80% greater (p < 0.001) and the apparent total body clearance of the drug from plasma (CL) was 34% lower (p < 0.05) than in the youngest group. The mean AUC(∞) of oxycodone was also 30-41% greater in the oldest group than in the age groups of 60-70 and 70-80 years (p < 0.05). Oxycodone plasma concentrations from 8 hours post-dose were >2-fold higher (p < 0.01) in patients aged >80 years than in patients aged 20-40 years. Noroxycodone AUC(∞) was increased in the oldest group compared with patients aged 20-40 and 60-70 years (p < 0.05). There were no significant sex-related differences in any of the pharmacokinetic parameters. Because 37 of the 41 patients were extensive metabolizers through CYP2D6, the effect of the CYP2D6 genotype on oxycodone pharmacokinetics could not be properly assessed. There was a linear correlation between GFR and CL (p < 0.01, coefficient of determination [r(2)] = 0.26), volume of distribution at steady state (p < 0.05, r(2) = 0.19) and AUC(∞) (p < 0.01, r(2) = 0.29) of oxycodone.

Conclusions: Age is an important factor affecting the pharmacokinetics of oxycodone. Following intravenous administration of oxycodone, patients aged >70 years are expected to have, on average, 40-80% higher exposure to oxycodone than young adult patients. Because oxycodone pharmacokinetics are greatly dependent on the age of the patient, it is important to titrate the analgesic dose individually, particularly in the elderly.
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http://dx.doi.org/10.2165/11586140-000000000-00000DOI Listing
January 2011

Predictive equations over-estimate the resting energy expenditure in amyotrophic lateral sclerosis patients who are dependent on invasive ventilation support.

Nutr Metab (Lond) 2010 Aug 26;7:70. Epub 2010 Aug 26.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital and University of Turku, Kiinamyllynkatu 4-8 FI-20520 Turku, Finland.

Background: Amyotrophic lateral sclerosis (ALS) is a form of degenerative motor neuron disease. At the end stage of the disease artificial feeding is often required. Nevertheless, very little is known about the energy demand of those ALS patients who are chronically dependent on tracheostomy intermittent positive pressure ventilation. The objective of our study was to clarify the resting energy expenditure (REE) in mechanically ventilated ALS patients.

Methods: We measured the REE of five ALS patients (four men, one female) twice during a 12 month-period using indirect calorimetry with two sampling flow settings (40 L/min and 80 L/min). The measured REEs (mREE) were compared with values calculated using five different predictive equations.

Results: The mean (± SD) of all mREEs was 1130 ± 170 kcal/d. The measurements with different flow settings and at different time instances provided similar results. The mean of mREEs was 33.6% lower, as compared to the mean calculated with five different predictive equations REE (p < 0.001). Each of the predictive equations over-estimated the REE.

Conclusions: The mREE values were significantly lower for every patient than all the predicted ones. Determination of daily nutrition with predictive equations may therefore lead in mis-estimation of energy requirements. Because ALS patients may live years with artificial ventilation their nutritional support should be based on individual measurements. However, further study is needed due to the small number of subjects.
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http://dx.doi.org/10.1186/1743-7075-7-70DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2939652PMC
August 2010

Highly variable pharmacokinetics of dexmedetomidine during intensive care: a case report.

J Med Case Rep 2010 Feb 25;4:73. Epub 2010 Feb 25.

Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, University of Turku and Turku University Hospital, FIN-20521, Turku, Finland.

Introduction: Dexmedetomidine is a selective and potent alpha2-adrenoceptor agonist licensed for use in the sedation of patients initially ventilated in intensive care units at a maximum dose rate of 0.7 mug/kg/h administered for up to 24 hours. Higher dose rates and longer infusion periods are sometimes required to achieve sufficient sedation. There are some previous reports on the use of long-term moderate to high-dose infusions of dexmedetomidine in patients in intensive care units, but none of these accounts have cited dexmedetomidine plasma concentrations.

Case Presentation: We describe the case of a 42-year-old Caucasian woman with severe hemorrhagic pancreatitis following laparoscopic cholecystectomy who received dexmedetomidine for 24 consecutive days at a maximum dose rate of 1.9 mug/kg/h. Samples for the measurement of dexmedetomidine concentrations in her plasma were drawn at intervals of eight hours. On average, the observed plasma concentrations were well in accordance with previous knowledge on the pharmacokinetics of dexmedetomidine. There was, however, marked variability in the concentration of dexmedetomidine in her plasma despite a stable infusion rate.

Conclusion: The pharmacokinetics of dexmedetomidine appears to be highly variable during intensive care.
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http://dx.doi.org/10.1186/1752-1947-4-73DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2848065PMC
February 2010

Pain assessment tools for unconscious or sedated intensive care patients: a systematic review.

J Adv Nurs 2009 May 9;65(5):946-56. Epub 2009 Mar 9.

Department of Nursing Science, University of Turku, Finland.

Aim: This paper is a report of a systematic review describing instruments developed for pain assessment in unconscious or sedated intensive care patients.

Background: Intensive care patients who are unconscious or sedated are unable to communicate and therefore recognition and assessment of the pain is difficult. To assess these patients' pain, it is important to use a valid and reliable pain assessment tool.

Data Sources: A systematic bibliographical review was conducted, based on seven databases, covering the period from January 1987 to February 2007. A total of 1,586 abstracts was identified and reviewed, 58 papers were selected for full-text review and nine papers were included in the review.

Methods: Two researchers independently reviewed the abstracts and three reviewers extracted the papers. The included papers were evaluated using a quality assessment instrument previously developed to evaluate pain assessment tools.

Results: Five different pain assessment tools were identified that had been used with unconscious or sedated intensive care patients. All five instruments included behavioural indicators and three included physiological indicators. Their psychometric properties varied and it was not possible to deduce their clinical utility.

Conclusion: All instruments were reasonably new. In most of them psychometric testing was in an early stage or even absent. Before any of the reported instruments can be chosen in preference to others, it is essential to test their validity, reliability and feasibility further.
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http://dx.doi.org/10.1111/j.1365-2648.2008.04947.xDOI Listing
May 2009

The effects of xenon anesthesia on the relationship between cerebral glucose metabolism and blood flow in healthy subjects: a positron emission tomography study.

Anesth Analg 2009 Feb;108(2):593-600

Turku PET Centre, University of Turku, Finland.

Background: General anesthetics can alter the relationship between regional cerebral glucose metabolism (rCMR(glc)) and blood flow (rCBF). In this positron emission tomography study, our aim was to assess both rCMR(glc) and rCBF in the same individuals during xenon anesthesia.

Methods: (18)F-labeled fluorodeoxyglucose and (15)O-labeled water were used to determine rCMR(glc) and rCBF, respectively, in five healthy male subjects at baseline (awake) and during 1 minimum alveolar anesthetic concentration of xenon. Anesthesia was based solely on xenon. Changes in rCMR(glc) and rCBF were quantified using region-of-interest and voxel-based analyses.

Results: The mean (sd) xenon concentration during anesthesia was 67.2 (0.8)%. Xenon anesthesia induced a uniform reduction in rCMR(glc), whereas rCBF decreased in 7 of 13 brain regions. The mean decreases in the gray matter were 32.4 (4.0)% (P < 0.001) and 14.8 (5.9)% (P = 0.007) for rCMR(glc) and rCBF, respectively. rCMR(glc) decreased by 10.9 (6.4)% in the white matter (P = 0.030), whereas rCBF increased by 9.2 (7.3)% (P = 0.049). The rCBF/rCMR(glc) ratio was especially increased in the insula, anterior and posterior cingulate, and in the somatosensory cortex.

Conclusions: In general, the magnitude of the decreases in rCMR(glc) during 1 minimum alveolar anesthetic concentration xenon anesthesia exceeded the reductions in rCBF. As a result, the ratio between rCMR(glc) and rCBF was shifted to a higher level. Interestingly, xenon-induced changes in cerebral metabolism and blood flow resemble those induced by volatile anesthetics.
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http://dx.doi.org/10.1213/ane.0b013e31818ffc9dDOI Listing
February 2009

Xenon does not affect gamma-aminobutyric acid type A receptor binding in humans.

Anesth Analg 2008 Jan;106(1):129-34, table of contents

Turku PET Centre, Turku, Finland.

Background: The noble gas xenon acts as an anesthetic with favorable hemodynamic and neuroprotective properties. Based on animal and in vitro data, it is thought to exert its anesthetic effects by inhibiting glutamatergic signaling, but effects on gamma-aminobutyric acid type A (GABA(A)) receptors also have been reported. The mechanism of anesthetic action of xenon in the living human brain still remains to be determined.

Methods: We used the specific GABA(A) receptor benzodiazepine-site ligand 11C-flumazenil and positron emission tomography to study the GABAergic effects of xenon in eight healthy male volunteers. Each subject underwent two dynamic 60-min positron emission tomography studies awake and during approximately one minimum alveolar concentration of xenon (65%). Bispectral index was recorded. Cortical and subcortical gray matter regions were analyzed using both automated regions-of-interest analysis and voxel-based analysis.

Results: During anesthesia, the mean +/- sd bispectral index was 23 +/- 7, and there were no significant changes in heart rate or mean arterial blood pressure. Xenon did not significantly affect 11C-flumazenil binding in any brain region.

Conclusions: Xenon did not affect 11C-flumazenil binding in the living human brain, indicating that the anesthetic effect of xenon is not mediated via the GABA(A) receptor system.
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http://dx.doi.org/10.1213/01.ane.0000287658.14763.13DOI Listing
January 2008

Bispectral index, entropy, and quantitative electroencephalogram during single-agent xenon anesthesia.

Anesthesiology 2008 Jan;108(1):63-70

Turku Positron Emission Tomography (PET) Centre, and Department of Anesthesiology and Intensive Care, Turku University Hospital, Turku, Finland.

Background: The aim was to evaluate the performance of anesthesia depth monitors, Bispectral Index (BIS) and Entropy, during single-agent xenon anesthesia in 17 healthy subjects.

Methods: After mask induction with xenon and intubation, anesthesia was continued with xenon only. BIS, State Entropy and Response Entropy, and electroencephalogram were monitored throughout induction, steady-state anesthesia, and emergence. The performance of BIS, State Entropy, and Response Entropy were evaluated with prediction probability, sensitivity, and specificity analyses. The power spectrum of the raw electroencephalogram signal was calculated.

Results: The mean (SD) xenon concentration during anesthesia was 66.4% (2.4%). BIS, State Entropy, and Response Entropy demonstrated low prediction probability values at loss of response (0.455, 0.656, and 0.619) but 1 min after that the values were high (0.804, 0.941, and 0.929). Thereafter, equally good performance was demonstrated for all indices. At emergence, the prediction probability values to distinguish between steady-state anesthesia and return of response for BIS, State Entropy, and Response Entropy were 0.988, 0.892, and 0.992. No statistical differences between the performances of the monitors were observed. Quantitative electroencephalogram analyses showed generalized increase in total power (P < 0.001), delta (P < 0.001) and theta activity (P < 0.001), and increased alpha activity (P = 0.003) in the frontal brain regions.

Conclusions: Electroencephalogram-derived depth of sedation indices BIS and Entropy showed a delay to detect loss of response during induction of xenon anesthesia. Both monitors performed well in distinguishing between conscious and unconscious states during steady-state anesthesia. Xenon-induced changes in electroencephalogram closely resemble those induced by propofol.
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http://dx.doi.org/10.1097/01.anes.0000296106.52472.a6DOI Listing
January 2008
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