ABSTRACT
This study aimed to determine the effect of a single injection of paracetamol on the sevoflurane minimum alveolar concentration (MAC) response to noxious mechanical stimulation. Seven healthy adult beagles were enrolled in a prospective, randomized, blinded, crossover experimental study. Anesthesia was induced with propofol [11.6 ± 2.4 mg/kg body weight (BW)] and maintained with sevoflurane. The MAC was determined before (MAC-1) and after (MAC-2) treatment with 15 mg/kg BW of intravenous (IV) paracetamol or saline over 15 minutes. Samples for plasma paracetamol determination were collected immediately after IV treatment administration and following MAC-2 determination (123 ± 27 minutes after starting paracetamol administration). The MAC-1 was similar between treatments (1.7% ± 0.4%). There were no differences between control and paracetamol groups at MAC-2 (2.0% ± 0.4% and 1.7% ± 0.5%, respectively; P = 0.285). Paracetamol plasma concentrations after paracetamol administration were 34.5 ± 9.9 µg/mL, decreasing at the end of the procedure (8.5 ± 4.2 µg/mL). In conclusion, 15 mg/kg BW of IV paracetamol did not significantly reduce sevoflurane MAC in healthy dogs.
La présente étude visait à déterminer l'effet d'une injection unique de paracétamol sur la réponse de la concentration alvéolaire minimale (MAC) de sévoflurane à une stimulation mécanique nocive. Sept chiens adultes en santé de race Beagle participèrent à une étude croisée prospective, randomisée, et à l'aveugle. L'anesthésie fut induite avec du propofol [11,6 ± 2,4 mg/kg de poids corporel (BW)] et maintenue avec du sévoflurane. La MAC fut déterminée avant (MAC-1) et après (MAC-2) traitement par voie intraveineuse (IV) avec 15 mg/kg BW de paracétamol ou de saline sur une période de 15 minutes. Des échantillons pour déterminer le paracétamol plasmatique furent prélevés immédiatement après l'administration IV du traitement et suivant la détermination de MAC-2 (123 ± 27 minutes après le début de l'administration de paracétamol). La valeur de MAC-1 était similaire entre les traitements (1,7 % ± 0,4 %). Il n'y avait pas de différence entre les groupes témoins et paracétamol à MAC-2 (2,0 % ± 0,4 % et 1,7 % ± 0,5 %, respectivement; P = 0,285). Les concentrations plasmatiques de paracétamol après l'administration de paracétamol étaient de 34,5 ± 9,9 µg/mL, et diminuaient à la fin de la procédure (8,5 ± 4,2 µg/mL). En conclusion, 15 mg/kg de BW de paracétamol par voie IV n'a pas réduit de manière significative la MAC de sévoflurane chez des chiens en santé.(Traduit par Docteur Serge Messier).
Subject(s)
Acetaminophen/pharmacology , Analgesics, Non-Narcotic/pharmacology , Anesthetics, Inhalation/metabolism , Dogs/metabolism , Pulmonary Alveoli/metabolism , Sevoflurane/metabolism , Acetaminophen/administration & dosage , Analgesics, Non-Narcotic/administration & dosage , Anesthetics, Intravenous/administration & dosage , Animals , Cross-Over Studies , Double-Blind Method , Female , Male , Propofol/administration & dosage , Prospective Studies , Random AllocationABSTRACT
OBJECTIVE: To compare a Parasympathetic Tone Activity (PTA) monitor with cardiovascular changes in invasive mean arterial pressure (IMAP) and heart rate (HR) when evaluating the response to nociceptive stimuli in anaesthetized dogs. STUDY DESIGN: Prospective experimental study. ANIMALS: A group of nine (seven male and two female) adult Beagle dogs weighing 13.4 ± 1.5 kg (mean ± standard deviation). METHODS: Anaesthesia was induced with propofol and maintained with sevoflurane in oxygen. Electrical stimuli of different nociceptive intensities were applied for 30 seconds. Stimuli were classified in each patient according to the response obtained (relevant change ≥ 20%) as low (no response), medium (PTA only) or high (PTA and IMAP/HR). Immediate and averaged values of PTA, IMAP and HR were recorded every second from 60 seconds before to 120 seconds after application of the nociceptive stimulus. Time to nociceptive response and peak response were evaluated with analysis of variance and t test. RESULTS: Immediate PTA baseline values did not differ significantly before application of the low, medium and high stimuli (73 ± 15, p = 0.966). Immediate PTA response was observed with the medium stimulus at 33 ± 7 seconds with a maximum decrease of 57 ± 13% at 69 ± 5 seconds. With the high stimulus, the immediate PTA response was of a similar magnitude to the medium stimulus with a response at 28 ± 7 seconds (p = 0.221) and a maximum decrease of 68 ± 15% (p = 0.115) at 72 ± 7 seconds (p = 0.436). The cardiovascular change occurred (22 ± 8 seconds) prior to the immediate PTA response (p = 0.032). CONCLUSIONS AND CLINICAL RELEVANCE: The PTA monitor detected nociceptive stimuli at lower intensities than those eliciting cardiovascular changes. However, nociceptive stimuli of higher intensities provoked cardiovascular changes that occurred before a PTA response was observed.
