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Bergen i fokus
- 2002
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Christiansson, Lennart, et al.
(författare)
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A new method of intrathecal PO2, PCO2, and pH measurements for continuous monitoring of spinal cord ischemia during thoracic aortic clamping in pigs
- 2000
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Ingår i: Surgery. - : Elsevier BV. - 0039-6060 .- 1532-7361. ; 127:5, s. 571-576
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Impaired spinal cord circulation during thoracic aortic clamping may result in paraplegia. Reliable and fast responding methods for intraoperative monitoring are needed to facilitate the evaluation of protective measures and efficiency of revascularization.METHODS: In 11 pigs, a multiparameter PO2, PCO2, and pH sensor (Paratrend 7, Biomedical Sensors Ltd, United Kingdom) was introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid (CSF) oxygenation during thoracic aortic cross-clamping (AXC) distal to the left subclavian artery. A laser-Doppler probe was inserted into the epidural space for simultaneous measurements of spinal cord flux. Registrations were made before and 30 minutes after clamping and 30 and 60 minutes after declamping. The same measuring points were used for systemic hemodynamic and metabolic data acquisition.RESULTS: The mean CSF PO2 readings of 41 mm Hg (5.5 kPa) at baseline decreased within 3 minutes to 5 mm Hg (0.7 kPa) during AXC (P < .01). Spinal cord flux measurement responded immediately in the same way to AXC. Both methods indicated normalization of circulation during declamping. Significant (P < .01) changes were also observed in the CSF metabolic parameters PCO2 and pH.CONCLUSIONS: In this experimental model of spinal ischemia by AXC, online monitoring of intrathecal PO2, PCO2, and pH showed significant changes and correlated well with epidural laser-Doppler flowmetry (P < .01).
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- Christiansson, Lennart, et al.
(författare)
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Aspects of the spinal cord circulation as assessed by intrathecal oxygen tension monitoring during various arterial interruptions in the pig
- 2001
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Ingår i: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 121:4, s. 762-772
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We sought to study the effect of various modes of interruption of the spinal cord blood supply on intrathecal oxygenation.METHODS: In 24 pigs intrathecal PO (2), PCO (2), and pH were continuously monitored with a multiparameter catheter (Paratrend 7, Biomedical Sensors; Diametrics Medical, Inc, St Paul, Minn) during and after aortic crossclamping or selective interruption of segmental arteries and proximal collateral circulation.RESULTS: Proximal aortic clamping (n = 6) produced complete ischemia, whereas a second clamp close to the celiac trunk (n = 4) partly protected against spinal cord ischemia. This is explained by prevention of the steal phenomenon in the excluded part of the aorta. Adding clamps to the subclavian arteries (n = 6) created complete spinal ischemia as the collateral circulation was interrupted. In another group (n = 4) all segmental arteries below T5 were occluded with no reaction in the intrathecal variables. Additional selective clamping of supreme intercostal arteries (n = 4) showed the relative importance of the subclavian and vertebral collateral pathways.CONCLUSIONS: Continuous intrathecal PO (2) was monitored during various modes of interruption of the spinal cord blood supply. This provided insight into the ischemia mechanisms and relative importance of the segmental contribution and proximal collateral pathways of the spinal cord circulation in pigs. A short literature review is given, and aspects of comparative anatomy are discussed.
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- Christiansson, Lennart, et al.
(författare)
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Increased FiO2 improves intrathecal oxygenation during thoracic aortic cross-clamping in pigs
- 2001
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Ingår i: Scandinavian Cardiovascular Journal. - 1401-7431 .- 1651-2006. ; 35:2, s. 147-150
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the effect of 100% oxygen ventilation on cerebrospinal fluid (CSF) oxygenation in 11 pigs during thoracic aortic cross-clamping.DESIGN: An aorto-aortic shunt was used for control of central hemodynamics and study of hypoperfusion by exsanguination. CSF PO2, PCO2 and pH were continuously monitored before and during clamping. The changes in hemodynamic parameters and intrathecal gas tensions in response to variations in proximal mean aortic pressure and fraction of inspired oxygen (FiO2) were recorded.RESULTS: Baseline CSF PO2 decreased from 4.8 +/- 1.9 to 2.6 +/- 2.2 kPa following aortic occlusion. Increasing FiO2 to 1.0 resulted in a significant increase in CSF PO2 to 4.1 +/- 3.0 with a return to 2.7 +/- 2.1 kPa after reducing FiO2 to 0.4 again. The same variations in FiO2 did not induce any significant changes in CSF PO2 during hypotension.CONCLUSION: Increased FiO2 during experimental thoracic aortic cross-clamping with stable proximal arterial pressure helps to maintain CSF PO2, whereas severe hypotension could not be compensated for by hyperoxemia.
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- Christiansson, Lennart, et al.
(författare)
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Relationship between intrathecal oxygen tension and ultrastructural changes in the spinal cord during experimental aortic clamping
- 2000
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Ingår i: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884 .- 1532-2165. ; 19:4, s. 413-420
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate spinal cord ultrastructure related to cerebrospinal fluid (CSF) oxygenation.DESIGN: experimental aortic occlusion model with intrathecal oxygen tension monitoring.MATERIALS AND METHODS: Two groups of pigs underwent proximal (P) or double (D) aortic occlusion for 30 min followed by 1 h of reperfusion. In a third group (I) segmental arteries distal to T3 were clamped for 90 min. A thin pO(2), pCO(2) and pH sensor was placed intrathecally for continuous monitoring of CSF. Spinal cord segments were studied by electron microscopy (EM).RESULTS: In group P, CSF-pO(2)rapidly decreased during clamping and major changes in pH and pCO(2)were seen. EM demonstrated neuronal degeneration with loss of cellular integrity and severe affection of organelles. In the group D, CSF oxygenation decreased to about half, but with only moderate changes in the metabolic parameters. Group I showed no significant changes in CSF measurements. The latter groups were similar at EM, showing only mild mitochondrial changes.CONCLUSIONS: The level of CSF oxygenation during aortic cross-clamping or segmental artery interruption seems to correlate with ultrastructural changes in the spinal cord. This online intrathecal monitoring technique may provide valuable information on spinal cord circulation during thoracoabdominal aortic surgery.
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- Christiansson, Lennart
(författare)
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Spinal cord ischemia : An experimental study of the spinal cord blood supply and peroperative ischemia detection by a new method of intrathecal monitoring
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Spinal cord ischemia associated with thoracoabdominal aortic surgery may lead to devastating neurological complications. Improvement in bypass techniques and various adjunctive measures has reduced its incidence, but still 5-10 % of the patients develop postoperative paraplegia. There is no universally accepted method for the detection of spinal cord ischemia. Intraoperative monitoring methods are important for the prediction of ischemia and guidance in aorticreplacement strategy. This thesis presents a new technique for continuous peroperative monitoring of intrathecal oxygenation.A multiparameter sensor was used to measure cerebrospinal fluid (CSF) PO2, PCO2 and pH during thoracic aortic cross-clamping in pigs. The findings were experimentally validated by comparisons with epidural laser-Doppler flowmetry and with morphological outcome, as assessed by electron microscopy of immersion fixated spinal cord specimens. The CSF monitoring was used to study functional aspects of segmental and collateral spinal cord blood supply. An experimental model was developed for the study of selective spinal cord ischemia. For this purpose a passive aortic shunt was used.The new monitoring method correlated in the experimental situation with measurements of microcirculation and changes in spinal cord ultrastructure associated with aortic cross-clamping. It proved to be sensitive for detecting ischemia and responded rapidly to alterations in spinal cord circulation. The confounding hemodynamic effects of cross-clamping and systemic reperfusion injuries to the spinal cord could be avoided in the selective ischemia model. The shunt model was also used to study the beneficial effects of hyperoxemia during spinal cord hypoperfusion. In conclusion, this thesis presents a new monitoring method for spinal cord oxygenation during experimental aortic occlusion. The thin flexible sensor can be used percutaneously in humans and comparative studies are needed to correlate the findings with neurophysiological evaluations and clinical outcome.
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| 10. |
- Christiansson, Lennart
(författare)
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Update on adjuvants in regional anaesthesia
- 2009
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Ingår i: Periodicum biologorum. - 0031-5362. ; 111:2, s. 161-170
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Forskningsöversikt (refereegranskat)abstract
- This is a review article on adjuvants to neuroaxial anaesthesia and peripheral nerve blocks used in clinical practice: opioids, vasoconstrictors, clonidine, NMDA antagonists, midazolam, glucocorticoids, nonsteroidal anti-inflammatory drugs and neostigmine. Mechanisam and site of action of each of them is described. It is followed by discussion of experimental and clinical data published in the last five years.
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