Measurements of catecholamines during anaesthesia.
thesisposted on 19.11.2015, 08:43 by Kohath Jenge. Achola
Factors affecting catecholamine levels in vitro were studied using the modified high pressure liquid chromatography method with electrochemical detection. Differential centrifugation showed that platelet-rich plasma contained significantly higher catecholamine levels than platelet-poor plasma. Serum samples had significantly higher catecholamine levels than plasma. Plasma or serum samples clotted with glass beads had significantly higher catecholamine levels than those without. Therefore, consistent results can only be obtained when catecholamine samples are spun at the same speed, either plasma or serum can be used, but not both in a single study. Post-dated blood for transfusion was used to study stability of catecholamines, and showed that catecholamines are stable. Hence, the collection of blood samples for catecholamine measurements was modified. Blood samples were collected in Vacutainer tubes containing lithium heparin without antioxidants and not pre-cooled, samples were spun at the convenient time. This was welcomed by the clinicians who did not have to interrupt clinical assessment to care for blood samples as with the former method. The three clinical studies showed no significant differences in catecholamine levels in patients undergoing laryngoscopy with and without tracheal intubation, whether or not the patients were beta blocked or had received topical tracheal analgesia. The mean catecholamine levels were within the normal range. No relationships between baseline catecholamine levels and the baseline blood pressures or heart rate nor between the changes in catecholamine levels from the baseline and the corresponding changes in blood pressures or heart rate. The Injury Severity Score in minor injured patients had no relationship with plasma catecholamine levels, and no significant rise in noradrenaline levels when the ISS<30 and adrenaline levels when the ISS<17. The studies suggest that catecholamine levels are of no value in assessing the severity of minor injuries, or changes in blood pressures or heart rate during anaesthesia.