Effects of dexmedetomidine on hemodynamic, oxygenation, microcirculation, and inflammatory markers in a porcine model of sepsis

Purpose: To determine whether dexmedetomidine aggravates hemodynamic, metabolic variables, inflammatory markers, and microcirculation in experimental septic shock. Methods: Twenty-four pigs randomized into: Sham group (n = 8), received saline; Shock group (n = 8), received an intravenous infusion of Escherichia coli O55 (3 × 109 cells/mL, 0.75 mL/kg, 1 hour); Dex-Shock group (n = 8), received bacteria and intravenous dexmedetomidine (bolus 0.5 mcg/kg followed by 0.7 mcg/kg/h). Fluid therapy and/ornorepinephrine were administered to maintain a mean arterial pressure > 65 mmHg. Hemodynamic, metabolic, oxygenation, inflammatory markers, and microcirculation were assessed at baseline, at the end of bacterial infusion, and after 60, 120, 180, and 240 minutes. Results: Compared to Shock group, Dex-Shock group presented a significantly increased oxygen extraction ratio at T180 (23.1 ± 9.7 vs. 32.5 ± 9.2%, P = 0.0220), decreased central venous pressure at T120 (11.6 ± 1 vs. 9.61 ± 1.2 mmHg, P = 0.0214), mixed-venous oxygen saturation at T180 (72.9 ± 9.6 vs. 63.5 ± 9.2%, P = 0.026), and increased plasma lactate (3.7 ± 0.5 vs. 5.5 ± 1 mmol/L, P = 0.003). Despite the Dex-Shock group having a better sublingual vessel density at T240 (12.5 ± 0.4 vs. 14.4 ± 0.3 mL/m2; P = 0.0003), sublingual blood flow was not different from that in the Shock group (2.4 ± 0.2 vs. 2.4 ± 0.1 mL/kg, P = 0.4418). Conclusions: Dexmedetomidine did not worsen the hemodynamic, metabolic, inflammatory, or sublingual blood flow disorders resulting from septic shock. Despite inducing a better sublingual vessel density, dexmedetomidine initially and transitorily increased the mismatch between oxygen supply and demand.

Avaliação da dexmedetomidina e do tramadol, associados ao midazolam, em gatas anestesiadas com isoflurano e submetidas à ovário-histerectomia / Evaluation of dexmedetomidine and tramadol, associated with midazolam, in cats anesthetized with isoflurane, undergoing ovariohysterectomy

Objetivou-se comparar as alterações cardiorrespiratórias e a analgesia pós-operatória promovidas pela dexmedetomidina e pelo tramadol, quando associados ao midazolam, em felinas. Para tal, foram selecionadas 18 gatas hígidas, divididas em dois grupos randomizados: GDM, tratadas com dexmedetomidina (10µg/kg) e GTM, tratadas com tramadol (2mg/kg), ambos associados a midazolam (0,2mg/kg,) IM. Após 15 minutos, procedeu-se à indução anestésica com propofol (1,46±0,79mL), mantendo-se a anestesia com isoflurano. As felinas foram submetidas à ovário-histerectomia, registrando-se as variáveis cardiorrespiratórias 15 minutos após a MPA (M0), 15 minutos após a indução (M15) e sequencialmente a cada cinco minutos, até o término do procedimento cirúrgico (M20, M25, M30, M35 e M40). A avaliação da dor iniciou-se 30 minutos após o término do procedimento cirúrgico (MP30) e sequencialmente em intervalos de 30 minutos (MP60, MP90, MP120). A partir do MP120, as avaliações foram registradas a cada hora (MP180, MP240 e MP360). A associação dexmedetomidina-midazolam infere diminuição inicial de frequência cardíaca (FC) sem significado clínico e está relacionada à sedação mais pronunciada, à analgesia menor e menos duradoura e a episódios de êmese, quando comparada à associação tramadol-midazolam. Ambos os protocolos denotaram estabilidade cardiorrespiratória e podem ser considerados seguros em felinas submetidas à ovário-histectomia.(AU)

The aim of this study was to compare cardiorespiratory changes and post-operative analgesia provided by dexmedetomidine or tramadol, associated with midazolam, in female cats. For that purpose, 18 healthy cats were assigned to two randomized groups: GDM, which received dexmedetomidine (10 µg/kg) and GTM, which received tramadol (2 mg/kg), both associated with midazolam (0.2 mg/kg) IM. After 15 minutes, anesthesia was induced with propofol (1.46±0.79 mL) and maintained with isofluorane. Ovariohysterectomy was performed and cardiorespiratory variables were registered 15 minutes after pre-anesthetic medication (M0), 15 minutes after anesthetic induction (M15), and every five minutes until the end of the surgical procedure (M20, M25, M30, M35 e M40). Pain evaluation started 30 minutes after the surgery (MP30) and sequentially at thirty-minute intervals (MP60, MP90, MP120). After MP120, each evaluation was registered at every hour (MP180, MP240 e MP360). Dexmedetomidine-midazolam association results in decreases on initial heart rate (HR) without clinical relevance and it is related to pronounced sedation, poor and less durable antinociception and vomiting events, when compared to tramadol-midazolam association. Both protocols indicate cardiorespiratoy stability and safety in cats undergoing ovariohysterectomy.(AU)