Wirkung von milder Hypothermie auf den negativ inotropen Effekt von Halothan, Isofluran und Sevofluran auf ventrikuläres Kaninchen-Myokard

The aim of this study was to dertermine wheather mild hypothermia changes the negative inotropic response of the volatile anesthetics halothane, isoflurane and sevoflurane on ventricular rabbit myocardium. Measured parameters were contractility, the timing of contractions, response to the raise of extracellular calcium concentrations and the first contraction after a time interval without stimulation, each at 31°C, 34°C, 37°C and 40°C. The specimen were trabeculae and papillary muscles from the right ventricle of New Zealand white rabbits. After reaching the steady state and acheiving the target temperature, the dose-response relation of the pharmaca mentioned above was determined. Hypothermia showed an positive inotropic effect as expected. Our study showed that mild hypothermia lowers the negative inotropic effect of halothane, isoflurane and sevoflurane. Volatile anesthetics decelarate the velocity of contraction and relaxation. Lower temperatures attenuate this deceleration too. Mild hypothermia extends the time of contraction and relaxation. Differences due to the temperature can only be found under the influence of isoflurane and sevoflurane. Raising the extracellular calcium concentration at 37°C leads to an important increase in contractility, which is considerably lowered by hypothermia, independent of the anesthetic used. The first contraction after a 10 second interval without stimulation showed no significant deviation. After 60 seconds without stimulation, sevoflurane causes an temperature dependent decrease of the contractile force of the first contraction under mild hypothermia. The mean variation of these experiments was extremely elevated, so that statments must be regarded with extreme care. The lowering of the negative inotropic effect of volatile anesthetics has not been described in that way in literature. Though, the explanation of our results ist quite difficult, because the reason of neither the negativ inotropic effect of volatile anesthetics nor the positive inotropic effect of mild hypothermia has yet been decrypted on the subcellular level. Some theories describe as well as for hypothermia as for volatile anesthetics influences on the ionic current through the cell membrane, the calcium sensitivity of the myofibrills and the calcium content of the sarcoplasmatic reticulum. The most probable explanation would finally be an interaction of all enumerated facts that leads in the sum to a decrease of the negative inotropic effect of volatile anesthetic under mild hypothermia.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2011

Author dc:creator

• Tompers, Jo

Contributors dc:contributor

• Buhre, Wolfgang Friedrich

• info:eu-repo/classification/ddc/610
• Hypothermie
• Negative Inotropie
• Halothan
• Isofluran
• Sevofluran
• Herzmuskel
• Medizin
• hypothermia
• volatile anesthetics
• myocardium
• negatic inotropy

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124472%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:63001