933 research outputs found
Washington University Record, March 20, 2008
https://digitalcommons.wustl.edu/record/2136/thumbnail.jp
Tehohoitopotilaiden neuromonitorointi
In critical illness the risk of neurological insults is high, whether because of the illness itself, or as a treatment complication. As a result, the length of hospital stay and the risk of both further morbidity and mortality are all roughly doubled. One of the major challenges is the inability to monitor a sedated, mechanically ventilated patientâs neurological symptoms during intensive care treatment, due to a lack of reliable methods.
The aims of this thesis research were to identify and test potential non-invasive methods, which would be predictive of neurological outcome, showing potential as neuromonitoring methods of critical care patients unable to self-report. As a guiding theme, all tested methods could be applied to actual critical care with relative ease.
Patients were included from two groups with a notably high incidence of neurological complications, namely acute liver failure patients with hepatic encephalopathy (I), and aortic surgery patients operated during hypothermic circulatory arrest (II). The first group included 20 patients, and the latter 30 patients. Late mortality and quality of life was assessed for the aortic surgery patients (III), and the postoperative development of certain blood biomarkers (IV).
The tested non-invasive neuromonitoring methods included electroencephalogram (EEG) variables from frontal or fronto-temporal abbreviated monitoring, frontal near-infrared spectroscopy, transcranial Doppler ultrasound measurements of the intracranial blood flow, and finally biomarkers. The last included established biomarkers with an association with neurological complications, namely neuron-specific enolase, and protein S100ÎČ, and several interesting biomarkers normally associated with tumours and pancreatitis.
Of the tested methods, the frontal EEG variables showed greatest promise, but the addition of the temporal channels did not increase sensitivity. Spectral EEG variables were predictive of the stage of hepatic encephalopathy (I), while a novel EEG variable called wavelet subband entropy was predictive of neurological outcome (I). The hemispheric asymmetry of frontal EEG was reasonably predictive of neurological outcome after aortic surgery (II). None of the other tested methods were predictive of outcome (I, II, IV), except protein S100ÎČ, which was significantly higher in the poor outcome group 48 to 72 hours after hypothermic circulatory arrest (II). The quality of life of aortic surgery patients was good after 5 to 8 years, and comparable with the general population of chronically ill patients (III).
The aim of this explorative research was to identify and test non-invasive neuromonitoring methods, suitable for use in critical care. Based on the results, frontal EEG variables are promising and predict the grade of hepatic encephalopathy and neurological outcome. The other tested methods were not predictive of neurological outcome. The long-term quality of life of aortic surgery patients is very good, despite the high risk for neurological complications.KriittisissÀ sairauksissa neurologisen komplikaation riski on suuri, sekÀ itse kriittisen sairauden ettÀ varsinaisen hoidon seurauksena. Haittatapahtuman johdosta sairaalahoidon kesto sekÀ sairastuvuuden ja kuolleisuuden riskit kaksinkertaistuvat. Yksi suurimmista haasteista on luotettavien menetelmien puute, joilla voitaisiin arvioida mekaanisen hengitystuen varassa olevan ja rauhoittavia lÀÀkkeitÀ saavan potilaan neurologisia oireita tehohoidon aikana.
TÀmÀn vÀitöskirjatyön tarkoituksena oli tunnistaa ja testata lupaavia ei-kajoavia menetelmiÀ, jotka ennustaisivat neurologista lopputulosta, ja jotka soveltuisivat kriittisesti sairaan tehohoitopotilaan neuromonitorointiin. Kantavana teemana kaikki testatut menetelmÀt voitaisiin soveltaa kliiniseen työhön suhteellisen helposti.
Potilaita kerÀttiin kahteen ryhmÀÀn, joissa neurologisten komplikaatioiden esiintyvyys on huomattavan suuri. EnsimmÀinen ryhmÀ kÀsitti akuuttia maksan vajaatoimintaa ja hepaattista enkefalopatiaa sairastavat potilaat (I), toinen hypotermisen verenkierron pysÀytyksen aikana rinta-aortan leikkauksen lÀpikÀyvÀt potilaat (II). EnsimmÀiseen ryhmÀÀn kuului 20 potilasta, jÀlkimmÀiseen 30 potilasta. Aorttaleikatuilta potilailta arvioitiin myös elÀmÀnlaatua sekÀ myöhÀiskuolleisuutta (III), lisÀksi tiettyjen biomerkkiaineiden aorttaleikkauksen jÀlkeistÀ kehitystÀ ja soveltuvuutta neuromonitorointiin arvioitiin yhdessÀ osatyössÀ (IV).
Tutkimuksessa arvioituihin ei-kajoaviin neuromonitorointimenetelmiin lukeutuivat otsa- ja ohimolohkon elektroenkefalografia (EEG), lĂ€hi-infrapunaspektroskopia, transkraniaalinen Doppler-ultraÀÀnimittaus sekĂ€ verestĂ€ mitattavat biomerkkiaineet. Biomerkkiaineet kattoivat sekĂ€ vakiintuneita aivovauriota heijastavia merkkiaineita (hermostoperĂ€inen enolaasi, proteiini S100ÎČ) ettĂ€ useita mielenkiintoisia merkkiaineita, jotka liittyvĂ€t kasvaintauteihin ja haimatulehdukseen.
Testatuista menetelmistĂ€ otsalohkon EEG muuttujat olivat lupaavia, mutta ohimolohkon EEG lisÀÀminen ei parantanut menetelmien herkkyyttĂ€. EEG spektrimuuttujat ennustivat hepaattisen enkefalopatian astetta (I) luotettavasti, kun taas kokeellinen EEG-muuttuja (aalloke-alitaajuuden entropia) ennusti luotettavasti neurologista lopputulosta akuutin maksan vajaatoimintaa sairastavilla potilailla (I). Otsalohkon aivopuoliskojen EEG-rekisteröinnin hetkellinen epĂ€symmetria ennusti kohtalaisella tarkkuudella neurologisten pÀÀtetapahtumien esiintymisen aorttaleikatuilla potilailla (II). Muut testatut menetelmĂ€t eivĂ€t ennustaneet neurologista lopputulemaa (I, II, IV), paitsi proteiini S100ÎČ, joka oli merkittĂ€vĂ€sti korkeampi 48â72 tuntia leikkauksen jĂ€lkeen niillĂ€ potilailla, joiden neurologinen toipuminen oli huono (IV). Aorttaleikattujen potilaiden elĂ€mĂ€nlaatu oli hyvĂ€ 5â8 vuotta leikkauksen jĂ€lkeen ja verrattavissa kroonisesti sairaan vĂ€estön elĂ€mĂ€nlaatuun (III).
TĂ€mĂ€n kartoittavan tutkimuksen tarkoituksena oli tunnistaa ja testata ei-kajoavia neuromonitorointimenetelmiĂ€, jotka soveltuvat tehohoitoon. Tulosten perusteella otsalohkon EEG-muuttujat ennustavat hepaattisen enkefalopatian astetta sekĂ€ potilaan neurologista toipumista. Muut testatut menetelmĂ€t eivĂ€t ennustaneet neurologista toipumista luotettavasti. Aorttaleikattujen potilaiden pitkĂ€aikainen (5â8 vuoden) terveyteen liittyvĂ€ elĂ€mĂ€nlaatu on erittĂ€in hyvĂ€, vaikka leikkaukseen liittyy korkea aivovaurion riski
Advanced Signal Processing and Control in Anaesthesia
This thesis comprises three major stages: classification of depth of anaesthesia (DOA); modelling a typical patientâs behaviour during a surgical procedure; and control of DOAwith simultaneous administration of propofol and remifentanil. Clinical data gathered in theoperating theatre was used in this project.
Multiresolution wavelet analysis was used to extract meaningful features from the auditory evoked potentials (AEP). These features were classified into different DOA levels using a fuzzy relational classifier (FRC). The FRC uses fuzzy clustering and fuzzy relational composition. The FRC had a good performance and was able to distinguish between the DOA levels.
A hybrid patient model was developed for the induction and maintenance phase of anaesthesia. An adaptive network-based fuzzy inference system was used to adapt Takagi-Sugeno-Kang (TSK) fuzzy models relating systolic arterial pressure (SAP), heart rate (HR), and the wavelet extracted AEP features with the effect concentrations of propofol and remifentanil. The effect of surgical stimuli on SAP and HR, and the analgesic properties of remifentanil were described by Mamdani fuzzy models, constructed with anaesthetist cooperation. The model proved to be adequate, reflecting the effect of drugs and surgical stimuli.
A multivariable fuzzy controller was developed for the simultaneous administration of propofol and remifentanil. The controller is based on linguistic rules that interact with three decision tables, one of which represents a fuzzy PI controller. The infusion rates of the two drugs are determined according to the DOA level and surgical stimulus. Remifentanil is titrated according to the required analgesia level and its synergistic interaction with propofol. The controller was able to adequately achieve and maintain the target DOA level, under different conditions.
Overall, it was possible to model the interaction between propofol and remifentanil, and to successfully use this model to develop a closed-loop system in anaesthesia
Characterisation of awakening from anaesthesia in infants
There is uncertainty about the doses of anaesthetic drugs required for unconsciousness in
infants. It is important to both avoid inadequate doses leading to intraoperative awareness
and also excess doses that may harm the developing brain. Depth of anaesthesia
monitoring has been developed in adults based upon electroencephalography (EEG). The
EEG of infants is different and few data are available. Heart rate variability (HRV) using
the ECG is another non-invasive tool that could be used in infants. The hypothesis of this
thesis is that EEG and HRV could help predict or warn of awakening after anaesthesia.
Awakening was defined by a panel of experts as at least 2 of crying, coughing, vigorous
limb movements, eyes open or looking around. A suitable clinical model of awakening
from anaesthesia was determined in a series of pilot studies. Intubated infants
anaesthetised with sevoflurane were studied after surgery. Tickling the foot proved a
reliable stimulus to cause awakening. EEG and HRV were monitored at the end of
surgery during emergence. Events and behaviour were videoed and characteristics of
EEG and HRV were identified. After awakening began EMG and other interference
made signals difficult to interpret. In all infants there was negligible EEG power in
frequencies higher than 20Hz and most power was in frequencies less than 5Hz. Infants
older than 52 weeks post menstrual age (PMA) had an oscillatory characteristic within
the 5 to 20 Hz range during anaesthesia that reduced in power appreciably as sevoflurane
levels decreased; power in 5-20 Hz reduced to less than 100 ÎŒV2 before awakening began
which may provide a potential warning of awakening. Infants less than 52 weeks PMA
had low EEG power in 5-20 Hz throughout. EEG power in this frequency band during
anaesthesia increases with age. HRV was low during anaesthesia but increased before
awakening began. HRV low frequency power increased in bursts as anaesthesia levels
decreased. A case report demonstrated the potential value of P5-20Hz and LF HRV band
power in the development of intraoperative depth of anaesthesia monitoring in infants
older than 52 weeks PMA
Acute lung injury in paediatric intensive care: course and outcome
Introduction: Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) carry a high morbidity and mortality (10-90%). ALI is characterised by non-cardiogenic pulmonary oedema and refractory hypoxaemia of multifactorial aetiology [1]. There is limited data about outcome particularly in children. Methods This retrospective cohort study of 85 randomly selected patients with respiratory failure recruited from a prospectively collected database represents 7.1% of 1187 admissions. They include those treated with High Frequency Oscillation Ventilation (HFOV). The patients were admitted between 1 November 1998 and 31 October 2000. Results: Of the 85, 49 developed acute lung injury and 47 had ARDS. There were 26 males and 23 females with a median age and weight of 7.7 months (range 1 day-12.8 years) and 8 kg (range 0.8-40 kg). There were 7 deaths giving a crude mortality of 14.3%, all of which fulfilled the Consensus I [1] criteria for ARDS. Pulmonary occlusion pressures were not routinely measured. The A-a gradient and PaO2/FiO2 ratio (median + [95% CI]) were 37.46 [31.82-43.1] kPa and 19.12 [15.26-22.98] kPa respectively. The non-survivors had a significantly lower PaO2/FiO2 ratio (13 [6.07-19.93] kPa) compared to survivors (23.85 [19.57-28.13] kPa) (P = 0.03) and had a higher A-a gradient (51.05 [35.68-66.42] kPa) compared to survivors (36.07 [30.2-41.94]) kPa though not significant (P = 0.06). Twenty-nine patients (59.2%) were oscillated (Sensormedics 3100A) including all 7 non-survivors. There was no difference in ventilation requirements for CMV prior to oscillation. Seventeen of the 49 (34.7%) were treated with Nitric Oxide including 5 out of 7 non-survivors (71.4%). The median (95% CI) number of failed organs was 3 (1.96-4.04) for non-survivors compared to 1 (0.62-1.62) for survivors (P = 0.03). There were 27 patients with isolated respiratory failure all of whom survived. Six (85.7%) of the non-survivors also required cardiovascular support.Conclusion: A crude mortality of 14.3% compares favourably to published data. The A-a gradient and PaO2/FiO2 ratio may be of help in morbidity scoring in paediatric ARDS. Use of Nitric Oxide and HFOV is associated with increased mortality, which probably relates to the severity of disease. Multiple organ failure particularly respiratory and cardiac disease is associated with increased mortality. ARDS with isolated respiratory failure carries a good prognosis in children
Observations on the Pharmacokinetics and Pharmacodynamics of Dexmedetomidine. Clinical Studies on Healthy Volunteers and Intensive Care Patients
Patients treated in intensive care units require sedation and analgesia. However,
sedative drugs also have potential adverse effects, and there is no single ideal sedativeanalgesic
drug for these patients.
Dexmedetomidine is an apha2-adrenoceptor agonist licenced for sedation of intensive care
patients and patients undergoing surgery and other invasive procedures. Several routes
of parenteral administration (intravenous, intramuscular, subcutaneous and intranasal)
have been utilized.
In the present series of studies, the pharmacokinetics and pharmacodynamics of
intranasally administered dexmedetomidine as well as the gastrointestinal effects of
intravenous dexmedetomidine were determined in healthy volunteers. Pharmacokinetics
of dexmedetomidine during long lasting, high-dose infusions were characterized
in intensive care patients.
The bioavailability of intranasal dexmedetomidine was relatively good (65%), but
interindividual variation was large. Dexmedetomidine significantly inhibited gastric
emptying and gastrointestinal transit. In intensive care patients, the elimination half-life
of dexmedetomidine was somewhat longer than reported for infusions of shorter
duration and in less ill patients or healthy volunteers. Dexmedetomidine appeared to
have linear pharmacokinetics up to the studied dose rate of 2.5 ÎŒg/kg/h.
Dexmedetomidine clearance was decreasing with age and its volume of distribution
was increased in hypoalbuminaemic patients, resulting in a longer elimination half-life
and context-sensitive half-time.
Intranasally administered dexmedetomidine was efficacious and well tolerated, making
it appropriate for clinical situations requiring light sedation. The clinical significance of
the gastrointestinal inhibitory effects of dexmedetomidine should be further evaluated
in intensive care patients. The possibility of potentially altered potency and effect
duration should be taken into account when administering dexmedetomidine to elderly
or hypoalbuminaemic patients.Siirretty Doriast
BrainâComputer Interface (BCI) Applications in Mapping of Epileptic Brain Networks Based on Intracranial-EEG: An Update
The main applications of the BrainâComputer Interface (BCI) have been in the domain of rehabilitation, control of prosthetics, and in neuro-feedback. Only a few clinical applications presently exist for the management of drug-resistant epilepsy. Epilepsy surgery can be a life-changing procedure in the subset of millions of patients who are medically intractable. Recording of seizures and localization of the Seizure Onset Zone (SOZ) in the subgroup of âsurgicalâ patients, who require intracranial-EEG (icEEG) evaluations, remain to date the best available surrogate marker of the epileptogenic tissue. icEEG presents certain risks and challenges making it a frontier that will benefit from optimization. Despite the presentation of several novel biomarkers for the localization of epileptic brain regions (HFOs-spikes vs. Spikes for instance), integration of most in practices is not at the prime time as it requires a degree of knowledge about signal and computation. The clinical care remains inspired by the original practices of recording the seizures and expert visual analysis of rhythms at onset. It is becoming increasingly evident, however, that there is more to infer from the large amount of EEG data sampled at rates in the order of less than 1 ms and collected over several days of invasive EEG recordings than commonly done in practice. This opens the door for interesting areas at the intersection of neuroscience, computation, engineering and clinical care. BrainâComputer interface (BCI) has the potential of enabling the processing of a large amount of data in a short period of time and providing insights that are not possible otherwise by human expert readers. Our practices suggest that implementation of BCI and Real-Time processing of EEG data is possible and suitable for most standard clinical applications, in fact, often the performance is comparable to a highly qualified human readers with the advantage of producing the results in real-time reliably and tirelessly. This is of utmost importance in specific environments such as in the operating room (OR) among other applications. In this review, we will present the readers with potential targets for BCI in caring for patients with surgical epilepsy
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