Neuromuscular monitoring during anesthesia

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/Open í sviðinuObjective: Muscle relaxants are very important in anesthetic practice but must be used with great care. Studies have shown that 17-40% of patients in postanesthesia care units (PACU) have residual muscle weakness. The purpose of this study was to evaluate whether the use of neuromuscular monitors during anesthesia could reduce the incidence of muscle weakness in the postoperative period. Materials and method: Eighty patients operated for laparoscopic cholecystectomy or lumbal disc prolapse given muscle relaxants during anesthesia were studied, randomly allocated to four groups. Fourty of these patients were monitored with neuromuscular monitor (TOF-guard") during anesthesia and the set point was a TOF-ratio of at least 70% before extubating the patients. Fourty patients were monitored by usual clinical signs (spontaneus breathing, cough and muscle movement). Twenty patients in each group were given vecuronium as muscle relaxant and 20 patients recieved pancuronium, again patients were randomly selected. In the PACU all patients were evaluated and the "5-sec headlift test" was used to find patients with muscle weakness. Hand grip strength was also measured before anesthesia and in the PACU. Glascow Coma Score (GCS) was used to evaluate if patients were too drowsy to co-operate and patients with GCS < 12 were excluded. Measurements were made after arrival to the PACU and every 30 minutes thereafter until headlift was at least 5 sec. Results: The incidence of restcurarization was 15% on arrival to the PACU. No statistically significant difference was found between those monitored with neuromuscular monitors and those that were not. Similarily no statistical difference was found between short acting neuromuscular blocking agents and longer acting agents. Conclusion: Although we didn t find any benefit from neuromuscular monitoring or using shorter acting drugs, the use of nervestimulators and short acting drugs is still recommended, especially for high risk patients. The generally accepted train-of-four (TOF-) ratio of 70% has been questioned by some authors, recommending a higher ratio (85%). Further studies using a higher TOF-ratio are therefore recommended.Tilgangur: Vöðvaslakandi lyf eru notuð við mikinn hluta svæfinga í dag. Æskilegt er að verkun þeirra sé horfin strax að svæfingu lokinni en kannanir hafa hins vegar sýnt að í 17-40% tilvika gæti áhrifa þeirra lengur. Tilgangur þessarar rannsóknar var að kanna hvort hægt væri að minnka eftirstöðvar vöðvaslökunar að svæfingu lokinni með nákvæmri vöktun með taugaörva meðan á svæfingu stendur og auka þannig öryggi sjúklinga eftir skurðaðgerðir. Efniviður og aðferðir: Valdir voru af handahófi 80 sjúklingar sem gengust undir skurðaðgerð á Sjúkrahúsi Reykjavíkur (nú Landspítali Fossvogi) þar sem vöðvaslökun var fyrirfram ákveðin. Helmingur sjúklinga (40 talsins) var vaktaður með taugaörva í svæfingu þar sem gefin eru fjögur væg rafstuð í röð (train-of-four, TOF) og fylgst með TOF-hlutfalli. Markmiðið var að TOF-hlutfall yrði að minnsta kosti 70% áður en sjúklingar væru vaktir og barkarenna fjarlægð. Hjá hinum 40 sjúklingunum var stuðst við klínísk einkenni, svo sem eigin öndun, hósta og vöðvahreyfingar til mats á vöðvaslökun. Tuttugu sjúklingar í hvorum hópi fengu vöðvaslakandi lyfið vecúróníum sem hefur miðlungslanga verkun og 20 sjúklingar fengu langverkandi lyfið pancúróníum. Eftirstöðvar vöðvaslökunar voru metnar á vöknunardeild með svokallaðri "fimm sekúndna höfuðlyftu" en hún er talin vera það klíníska próf sem best gefur til kynna hvort sjúklingur hafi endurheimt nægjanlegan vöðvastyrk til að halda öndunarvegi opnum og hreinum. Handstyrkur sjúklings var einnig mældur fyrir og eftir svæfingu. Þeir sjúklingar sem voru lægri en 12 samkvæmt Glasgow meðvitundarkvarða (Glasgow Coma Score, GCS) og því hugsanlega of sljóir eftir svæfinguna til að taka þátt í prófununum voru ekki teknir með fyrr en GCS var komið yfir 12 stig. Niðurstöður: Í ljós kom að 15% sjúklinga voru undir áhrifum vöðvaslakandi lyfja við komu á vöknunardeild. Sjúklingahóparnir voru sambærilegir varðandi almenn atriði, svo sem aldur, kyn, þyngd og blóðgildi. Notkun taugaörva með TOF-hlutfalli 70% reyndist ekki marktækt fækka sjúklingum með einkenni um vöðvaslökun eftir svæfingu. Munur á lyfjum með langa eða miðlungslanga verkun með tilliti til eftirstöðva vöðvaslökunar reyndist heldur ekki marktækur. Ályktun: Eftirstöðvar af áhrifum vöðvaslakandi lyfja eru nokkuð algengar (15%) hjá sjúklingum við komu á vöknunardeild. Hvorki notkun stuttverkandi lyfja né notkun fullkomins taugaörva fækkaði marktækt sjúklingum með minnkaðan vöðvastyrk eftir svæfingu en þó teljum við ástæðu til að mæla áfram með vöktun vöðvaslökunar, ekki síst við svæfingar áhættusjúklinga og í löngum aðgerðum. Til þessa hefur verið talið að 70% TOF-hlutfall nægði til þess að sjúklingurinn hefði nægilegan vöðastyrk í lok svæfingar. Nýleg rannsókn bendir hins vegar til þess að TOF-hlutfall þurfi að vera að minnsta kosti 85% til að fyrirbyggja eftirstöðvar vöðvaslökunar. Frekari rannsókna er þörf þar sem markmiðið væri hærra TOF-hlutfall

Risk profiles and prognosis of treated and untreated hypertensive men and women in a population-based longitudinal study: the Reykjavik Study

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldThe aim was to examine the risk profiles and prognosis of treated and untreated hypertensive subjects and examine to what degree confounding by indication was present in a population-based cohort study with up to 30-year follow-up. The study population consisted of 9328 men and 10 062 women, aged 33-87 years at the time of attendance from 1967 to 1996. The main outcome measures were myocardial infarction (MI), cardiovascular disease (CVD) mortality and all-cause mortality. Comparing the risk profiles between treated and untreated subjects entering the study showed significantly higher values for some risk factors for treated subjects. During the first 10 years, hypertensive men without treatment, compared with those treated, had a significantly lower risk of suffering MI, CVD and all-cause mortality, hazard ratio (HR) 0.72 (95% CI; 0.57, 0.90), 0.75 (95% CI; 0.59, 0.95) and 0.81 (95% CI; 0.61, 0.98), respectively. No significant differences in outcome were seen during the following 20 years. In identically defined groups of women, no significant differences in mortality were seen between groups. Subgroup analysis, at two stages of the study 5 years apart, revealed that some cardiovascular risk factors had a higher prevalence in hypertensive men who were treated at the later stage, compared with those who remained untreated (P=0.004). In conclusion, hypertensive treated men had a worse prognosis during the first 10 years of follow-up than untreated ones, which is most likely due to worse baseline risk profile. Hypertensive men that were treated at a later stage had a worse risk profile than those not treated at a later stage

Hekla 1947, 1845, 1510 and 1158 tephra in Finland: challenges of tracing tephra from moderate eruptions

Publisher's version (útgefin grein)Several cryptotephra layers that originate from Icelandic volcanic eruptions with a volcanic explosivity index (VEI) of ≤ 4 and tephra volumes of < 1 km3 have previously been identified in Northern Europe, albeit within a restricted geographical area. One of these is the Hekla 1947 tephra that formed a visible fall-out in southern Finland. We searched for the Hekla 1947 tephra from peat archives within the previously inferred fall-out zone but found no evidence of its presence. Instead, we report the first identification of Hekla 1845 and Hekla 1510 cryptotephra layers outside of Iceland, the Faroe Islands, Ireland and the UK. Additionally, Hekla 1158 tephra was found in Finland for the first time. Our results confirm that Icelandic eruptions of moderate size can form cryptotephra deposits that are extensive enough to be used in inter-regional correlations of environmental archives and carry a great potential for refining regional tephrochronological frameworks. Our results also reveal that Icelandic tephra has been dispersed into Finnish airspace at least seven times during the past millennium and in addition to a direct eastward route the ash clouds can travel either via a northerly or a southerly transport pathway.We thank Sami Jokinen for assistance with field work in Finland and Dr Maria Janebo for field assistance in Iceland. Professor Siwan Davies and Dr Gwydion Jones at Swansea University are thanked for their help with micromanipulator work. We are grateful to Dr Chris Hayward for support with EPMA at the University of Edinburgh. Financial support for field work and EPMA was received from the Finnish Cultural Foundation, Varsinais-Suomi Regional Fund and Suomen Tiedeseura. Maarit Kalliokoski acknowledges funding from the Nordic Volcanological Centre at the University of Iceland and the Doctoral Programme in Biology, Geography and Geology at the University of Turku.Peer Reviewe

Gravity and elevation changes at Askja, Iceland

Ground tilt measurements demonstrate that Askja is in a state of unrest, and that in the period 1988 - 1991 a maximum 48 +/- 3 µrad tilt occurred down towards the centre of the caldera. This is consistent with 126 mm of deflation at the centre of the caldera with a 2.5 - 3.0 km depth to the source of deformation. The volume of the subsidence bowl is 6.2 x 106 m3. When combined with high precision microgravity measurements, the overall change in sub-surface mass may be quantified. After correction for the observed elevation change using the free air gradient of gravity measured for each station, the total change in mass is estimated to be less than 109 kg. A small residual ground inflation and net gravity increase in the eastern part of the caldera may be caused by dyke intrusion in this region. The minimum dimensions of such an intrusion or complex of intrusions are 1m width, up to 100m deep and up to several hundred metres thick

Motion in the north Iceland volcanic rift zone accommodated by bookshelf faulting

Along mid-ocean ridges the extending crust is segmented1 on length scales of 10–1,000 km. Where rift segments are offset from one another, motion between segments is accommodated by transform faults that are oriented orthogonally to the main rift axis. Where segments overlap, non-transform offsets with a variety of geometries2 accommodate shear motions. Here we use micro-seismic data to analyse the geometries of faults at two overlapping rift segments exposed on land in north Iceland. Between the rift segments, we identify a series of faults that are aligned sub-parallel to the orientation of the main rift. These faults slip through left-lateral strike-slip motion. Yet, movement between the overlapping rift segments is through right-lateral motion. Together, these motions induce a clockwise rotation of the faults and intervening crustal blocks in a motion that is consistent with a bookshelf-faulting mechanism, named after its resemblance to a tilting row of books on a shelf3. The faults probably reactivated existing crustal weaknesses, such as dyke intrusions, that were originally oriented parallel to the main rift and have since rotated about 15° clockwise. Reactivation of pre-existing, rift-parallel weaknesses contrasts with typical mid-ocean ridge transform faults and is an important illustration of a non-transform offset accommodating shear motion between overlapping rift segments

Ice-confined construction of a large basaltic volcano—Austurfjöll massif, Askja, Iceland

Austurfjöll is the largest basaltic glaciovolcanic massif at Askja volcano (Central Iceland), and through detailed studies of its volcanological and geochemical characteristics, we provide a detailed account of the sequence and structure of the ice-confined construction of a large Icelandic basaltic volcano. In particular, Austurfjöll represents a geometry of vents, and resulting glaciovolcanic morphology, not previously documented in ice-confined basaltic volcanoes. Austurfjöll was constructed during two major phases of basaltic volcanism, via seven eruptive episodes through disperse fissure-dominated eruptions. The earliest episode involved a rare and poorly exposed example of subaerial activity, and this was succeeded by six episodes involving the eruption of ice-confined pillow lavas and numerous overlapping fissure eruptions of phreatomagmatic tephra. Evidence of local subaerial lavas and tephras indicates the local growth of eruptive centers above englacial lake levels, and subsequent flooding, but no prolonged subaerial activity. Localized ice-contact facies, paleowater levels, and diamictons indicate the position and thickness of the ice was variable during the construction of Austurfjöll, and eruptive activity likely occurred in multiple and variable level meltwater lakes during the last glacial period. Lithofacies evidence including gradational transitions from effusive to explosive deposits, superposition of fragmental facies above coherent facies, and drainage channels suggest that changes in eruptive style were driven largely by external factors such as drainage and the increasing elevation of the massif. This study emphasizes the unique character of Austurfjöll, being composed of large pillow lava sheets, numerous (> 40) overlapping glaciovolcanic tindars, and only localized emergent deposits, as a product of its prolonged ice-confined eruptive history, contrasts with previous descriptions of tuyas and tindars

Integration of micro-gravity and geodetic data to constrain shallow system mass changes at Krafla Volcano, N Iceland

New and previously published micro-gravity data are combined with InSAR data, precise levelling and GPS measurements to produce a model for the processes operating at Krafla volcano, 20 years after its most recent eruption. The data have been divided into two periods: from 1990 to 1995 and from 1996 to 2003 and show that the rate of deflation at Krafla is decaying exponentially. The net micro-gravity change at the centre of the caldera is shown, using the measured Free Air Gradient, to be -85 μGal for the first and -100 μGal for the second period. After consideration of the effects of water extraction by the geothermal power station within the caldera, the net gravity decreases are -73 ± 17 μGal for the first and -65 ± 17 μGal for the second period. These decreases are interpreted in terms of magma drainage. Following a Mogi point source model we calculate the mass decrease to be ~2 x 1010 kg/yr reflecting a drainage rate of ~0.23 m3/s, similar to the ~0.13 m3/s drainage rate previously found at Askja volcano, N-Iceland. Based on the evidence for deeper magma reservoirs and the similarity between the two volcanic systems, we suggest a pressure-link between Askja and Krafla at deeper levels (at the lower crust or the crust-mantle boundary). After the Krafla fires, co-rifting pressure decrease of a deep source at Krafla stimulated the subsequent inflow of magma, eventually affecting conditions along the plate boundary in N-Iceland, as far away as Askja. We anticipate that the pressure of the deeper reservoir at Krafla will reach a critical value and eventually magma will rise from there to the shallow magma chamber, possibly initiating a new rifting episode. We have demonstrated that by examining micro-gravity and geodetic data, our knowledge of active volcanic systems can be significantly improved

A rare missense mutation in CHRNA4 associates with smoking behavior and its consequences

Using Icelandic whole-genome sequence data and an imputation approach we searched for rare sequence variants in CHRNA4 and tested them for association with nicotine dependence. We show that carriers of a rare missense variant (allele frequency = 0.24%) within CHRNA4, encoding an R336C substitution, have greater risk of nicotine addiction than non-carriers as assessed by the Fagerstrom Test for Nicotine Dependence (P= 1.2 × 10−4). The variant also confers risk of several serious smoking-related diseases previously shown to be associated with the D398N substitution in CHRNA5. We observed odds ratios (ORs) of 1.7–2.3 for lung cancer(LC;P= 4.0 × 10−4), chronic obstructive pulmonary disease (COPD;P= 9.3 × 10−4), peripheral artery disease (PAD;P= 0.090) and abdominal aortic aneurysms (AAAs; P= 0.12), and the variant associates strongly with the early-onset forms of LC (OR = 4.49,P= 2.2 × 10−4), COPD (OR = 3.22,P= 2.9 × 10−4), PAD (OR = 3.47,P= 9.2 × 10−3) and AAA (OR = 6.44, P= 6.3 × 10−3). Joint analysis of the four smoking-related diseases reveals significant association (P= 6.8 × 10−5), particularly for early-onset cases (P=2.1 × 10−7). Our results are in agreement with functional studies showing that the human α4β2 isoform of the channel containing R336C has less sensitivity for its agonists than the wild-type form following nicotine incubation