Abstract
Seven sheep were sedated 3 times: with medetomidine (15 μg kg−1), with midazolam (0.1 mg kg−1) and with a combination of the drugs. All drugs were administered intravenously. Heart and respiratory rates were measured. Arterial blood samples were collected, and PaO2, PaCO2, pH, haemoglobin concentration and saturation, and base excess were determined. Systolic and mean arterial pressures were recorded before and after the treatment with medetomidine-midazolam.
Midazolam increased the time of recumbency induced by medetomidine. After administration of midazolam alone, 4 of the 7 sheep were sedated and the other 3 were excited. Heart rate decreased after both medetomidine and medetomidine-midazolam. One sheep suffered a cardiac arrest after medetomidine-midazolam injection, and it required resuscitation. PaO2 and haemoglobin oxygen saturation decreased after medetomidine, and medetomidine-midazolam caused a marked hypoxaemia. PaCO2 increased after medetomidine, both alone and combined with midazolam, but arterial pH was within the reference values after all drug administrations. Systolic and mean arterial pressures decreased after medetomidine-midazolam.
This study indicates that though in sheep midazolam potentiates the sedative effect of medetomidine, the combination of medetomidine and midazolam also reduces the in PaO2 and haemoglobin oxygen saturation more than medetomidine alone. The results indicate that a medetomidine-midazolam combination is unsafe for sheep at the doses studied. kw|Keywords|k]hypoxaemia; k]excitation; k]sheep
Sammanfattning
Sju far behandlades 3 gånger: med medetomidin (15 μg kg−1), med midazolam (0.1 mg kg−1) och med kombination av medetomidin och midazolam. Alla läkemedel gavs intravenöst. Hjärt- och andnigsfrekvens mättes. Arteriella blodprov togs, och PaO2, PaCO2, pH, koncentration av hemoglobin och dess syremättnad, och basöverskott bestämdes. Systoliskt och medelblodtryck mättes under sedering med kombinationen av medetomidin och midazolam.
Tiden som fåren låg ner var längre, när midazolam gavs tillsammans med medetomidin. Vid administrering av enbart midazolam blev några får sederade, medan de andra blev upphetsade. Hjärtfrekvensen sjönk både efter medetomidin och medetomidinmidazolam. Systoliska och medelblodtrycket sjönk efter medetomidin-midazolam. Ett får fick hjärtstillestånd efter medetomidin-midazolam och behövde återupplivning. PaO2 och hemoglobinets syremättnad minskade och PaCO2 ökade efter både medetomidin och medetomidin-midazolam, men artärblodets pH var inom riktvärdena efter alla behandlingar.
Resultaten i denna studie tyder på, att midazolam förstärker den lugnande verkan av medetomidin, men potentierar samtidigt sänkningen av PaO2 och hemogloginets syrehalt framkallade av medetomidin hos får.
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