Search

Bakgrunn: Eksperimentelle studier har vist at søvnmangel er assosiert med endringer i smertepersepsjon. Flere hjerneavbildningsstudier trengs for å utvikle objektive nevrofysiologiske korrelater til smerte. Hensikt: Denne studien undersøker hvordan søvnmangel påvirker opplevd smerteintensitet og elektrisk hjerneaktivitet under eksperimentell smertestimulering. Metode: Et innen-gruppe design ble brukt på et utvalg norske skiftarbeidere for å sammenligne opplevd smerteintensitet etter to netter med normalsøvn og to netter med søvnmangel. Smerteintensitet ble vurdert med en visuell analog skala (VAS). Elektrisk hjerneaktivitet ble målt med elektroencefalogram (EEG) gjennom en elektrodehette med 32 elektroder. Dynamisk spektralanalyse ble gjennomført på EEG signalene med Kontinuerlig Wavelet-Transformasjon. Statistisk analyse ble gjennomført med Mixed Models. EEG aktiviteten ble delt inn i de fem frekvensbåndene delta, theta, alpha, beta og gamma og analysert deretter. Både gjennomsnittlig aktivitetsnivå (static EEG indices) og dynamisk endring i aktiviteten (dynamic EEG indices) ble undersøkt. Resultater: Opplevd smerteintensitet var signifikant høyere etter to netter med søvnmangel enn etter to netter med normalsøvn. Opplevd smerteintensitet økte over de 2 minuttene med smertestimulering. Ingen signifikante endringer ble observert i de statiske EEG analysene. De dynamiske EEG analysene viste at økning i alfa-bånd aktivitet var assosiert med økning i smerteskårer etter normalsøvn. Etter søvnmangel var reduksjon i alfa-bånd aktivitet og thetabånd aktivitet assosiert med økning i smerteskårer. Konklusjon: Resultatene støtter tidligere funn om økt smerteintensitet etter søvnmangel. Aktivitet innen alfa-båndet og theta-båndet kan være assosiert med mekanismene som understøtter sammenhengen mellom søvn og smerte. Nøkkelord: hyperalgesi, smerteintensitet, søvnmangel, EEG, alfa aktivitet, theta aktivitet, nattarbeid Background: Experimental studies show that lack of sleep is associated with altered pain perception. Studies using brain imaging techniques are needed to further the development of objective neurophysiological correlates of pain. Objective: This thesis investigates how restricted sleep affects perceived pain intensity and electrical brain responses during experimental pain stimulation. Methods: A within-subject cross-over design was used on a sample of Norwegian shift workers in order to compare perceived pain intensity after two nights of habitual sleep, with perceived pain intensity after two nights of restricted sleep. Pain was induced by a 2-min contact-heat stimulation to the skin. Pain intensity was rated on a visual analogue scale (VAS). Brain responses were recorded with electroencephalogram (EEG) through a 32- electrode cap. Dynamic spectral analysis was performed on the EEG signals by the Continuous Wavelet Transform. Statistical analysis was performed by Linear Mixed Models. The EEG activity was analyzed in terms of the delta, theta, alpha, beta and gamma frequency ranges. Both the mean level of activity (static EEG indices) and the dynamics of the activity (dynamic EEG indices) were investigated. Results: Perceived pain intensity was significantly higher after restricted sleep as compared to habitual sleep. Pain intensity increased over the 2-min period. No significant sleep-dependent changes were found in any of the static EEG indices. The dynamic EEG indices showed that increased alpha activity was associated with increased pain scores after habitual sleep. Contrary, after restricted sleep, decreased alpha activity and decreased theta activity was associated with increased pain scores. Conclusion: The findings in this thesis strengthen the notion that sleep loss leads to an increase in perceived pain intensity. Brain mechanisms underlying the hyperalgesic effect of restricted sleep may involve alpha and theta activity. Keywords: hyperalgesia, restricted sleep, pain intensity, EEG, alpha band, theta band, night shift work

Different logging operations can suffer from presence of metallic particles in the drilling fluids. Directional drilling in Arctic areas can be a challenge because of magnetic contamination in the drilling fluid. This is a challenge especially when drilling east-west relative to the magnetic north direction. Magnetic and paramagnetic particles in the drilling fluid will shield the down hole compasses and introduce additional errors to the surveying than those normally included in the uncertainty ellipsoid. The objective of the project is to remove the magnetic particles being the largest contributor to this error. On many offshore drilling rigs there is mounted ditch magnets to remove metallic swarf from the drilling fluid. These magnets will normally only remove the coarser swarf. In this project we use a combination of strong magnets and flow directors to significantly improve the performance of the ditch magnets. This combination, together with proper routines for cleaning the ditch magnets significantly helps cleaning the drilling fluid. By the combined use of flow directors and ditch magnets it was possible to extract more than five times as much magnetic contamination from the drilling fluid. This is verified by comparing the ditch magnet efficiencies from two drilling rigs drilling ERD wells. The logging tool signal strengths of several down hole instruments were unusually good and insignificant down times were observed on the logging tools. The results are anticipated to have aided to the directional drilling performance. Detailed information on how to clean the drilling fluid properly from magnetic contamination is presented. It is also shown that this cleaning is significantly better than conventional cleaning of magnetic debris from drilling fluids.

A well documented path to improving overall efficiency in project execution is through an integrated team approach which involves both the operator and the service suppliers. This paper describes what can be achieved when such a team adopts a fearless approach to new technology, and dares to think outside existing conventions. To be more specific, the paper covers the engineering, planning, and execution of a HTHP exploration program in the central North Sea by a Norwegian operator. Large areas of the North Sea contain the Cretaceous period of sediments which comprise of a massive hard layer of chalk that historically has posed a major drilling risk and expense to operators in the area. To mitigate expected problems an integrated team was gathered to thoroughly analyze drilling records and lessons learned from previous offset wells and re-engineer the drilling process with the aim of minimizing cost and uncertainty when drilling the most challenging chalk interval. The paper presents the hypothesis that formed the basis for the team effort, and the measures implemented based on said hypothesis. This includes an unconventional bit selection and the use of modern vibration measurement technology and mitigation techniques, as well as a key electro-mechanical modification of the advanced logging and directional suite completed by the lead service provider. The discussion and reasoning behind each step is included and the method was repeated in several wells with the same results, verifying the validity of the findings and making the paper a valuable input for drilling hard chalk. The nominal result from applying the new methodology was a doubling of the rate of penetration (ROP) in the harder layers, and the entire section of problematic strata was drilled in one single bit run. Drilling time was reduced by 12 days when compared to average figures from recent offset wells representing an estimated cost saving of 15 - 20% on the overall well budget. The method and savings presented are primarily of interest to stakeholders in the central North Sea, but can also be applicable to other areas with hard chalk and stringers with similar characteristics.

In vitro experiments were performed in order to investigate the appearance of different types of central venous catheters at intravascular ultrasonography. The experiments were repeated with artificially produced thrombi which were made adherent to the catheter wall. All thrombi larger than 1 mm could be identified. In a clinical study including 12 patients who had a central venous catheter, transfemoral intravascular ultrasonography was performed. The catheters had been in place for an average period of 54 days (range 1–360 days). In 3 patients a catheter thrombus, mural thrombus, or occlusive vein thrombosis was found. In 2 of these patients the catheter was occluded, in the 3rd patient it was malpositioned into the contralateral brachiocephalic vein. There were no complications following the ultrasonographic procedures. Mean catheterization time was 7.5 min (range 3–20 min). The advantages of this new method compared with conventional phlebographic studies and its impact on further clinical investigations are discussed.

Eight patients with psoriasis, all with skin scales and 7 with disabling psoriatic arthritis, were subjected to cascade apheresis starting with three treatments per week for 2 weeks, followed by one treatment a week, comprising ten treatments in all. Six out of 7 patients (86%) with arthropathy and 3 out of 8 patients (38%) with scales experienced a beneficial effect. There was a large drop in the levels of circulating immune complexes (CIC) due to the treatment, and the removal of CIC was followed by reduced inflammatory activity in skin lesions and joints as evaluated by pain, morning stiffness, grip strength, plaque score, and PASI index. However, there was no correlation between the level of CIC, disease activity, or treatment response. From the present results it is concluded that CIC may play a more significant role regarding psoriatic arthropathy than in skin manifestations, and apheresis may be beneficial in patients not responding to conventional therapy.

In vitro experiments were performed in order to investigate the appearance of different types of central venous catheters at intravascular ultrasonography. The experiments were repeated with artificially produced thrombi which were made adherent to the catheter wall. All thrombi larger than 1 mm could be identified. In a clinical study including 12 patients who had a central venous catheter, transfemoral intravascular ultrasonography was performed. The catheters had been in place for an average period of 54 days (range 1-360 days). In 3 patients a catheter thrombus, mural thrombus, or occlusive vein thrombosis was found. In 2 of these patients the catheter was occluded, in the 3rd patient it was malpositioned into the contralateral brachiocephalic vein. There were no complications following the ultrasonographic procedures. Mean catheterization time was 7.5 min (range 3-20 min). The advantages of this new method compared with conventional phlebographic studies and its impact on further clinical investigations are discussed.