Haemodynamic response to simulated haemorrhage in the rabbit: interaction of i.v. anaesthesia and hypoxia

Blake, D.; Leeuwen, Andrew F. Van; Petring, O. U.; Ludbrook, John; Ventura, Sabatino

doi:10.1093/bja/75.5.610

Cited by 6 publications

(5 citation statements)

References 19 publications

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“…Dessa maneira, esperar-se-ia aumento da FC após a indução da hipovolemia, entretanto, tal evento não foi verificado em nenhum dos grupos estudados, isso porque os agentes anestésicos prejudicam o baroreflexo arterial, os quais podem abolir ou comprometer a resposta compensatória, já que a anestesia normalmente deprime a atividade nervosa simpática (BLAKE et al, 1995).…”

Section: Resultsunclassified

Diferentes frações inspiradas de oxigênio em coelhos hipovolêmicos anestesiados com propofol e submetidos à ventilação mecânica

et al. 2011

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Avaliaram-se os efeitos do fornecimento de diferentes frações inspiradas de oxigênio (FiO²) em coelhos hipovolêmicos, anestesiados com infusão contínua de propofol e mantidos em ventilação controlada sobre os parâmetros respiratórios, hemogasométricos e hemodinâmicos. Foram utilizados 50 coelhos (Nova Zelândia), pesando 3,5±0,3kg, distribuídos em 5 grupos: G100 (FiO²=1), G80 (FiO²=0,8), G60 (FiO²=0,6), G40 (FiO²=0,4) e G21 (FiO²=0,21), os quais receberam xilazina (1mg kg-1) e cetamina (15mg kg-1) pela via intramuscular. Transcorridos 20 minutos, foi administrado propofol (8mg kg-1 bolus e 0,5mg kg-1 min-1) e rocurônio (0,6mg kg-1 bolus e 0,6mg kg-1 h-1). Iniciou-se então, a ventilação mecânica no modo pressão controlada. Após 30 minutos, os animais foram submetidos à hipovolemia aguda, retirando-se sangue arterial (12mL kg-1). Os parâmetros foram mensurados 30 minutos após a indução anestésica (M0) e a cada dez minutos depois da exsanguinação (M1- M7). As variáveis foram submetidas à análise de variância seguida pelo teste de Tukey (P<0,05). Os valores de PaO², SaO², P A O², AaDO² diminuíram quanto mais baixas foram as FiO². Após a indução da hipovolemia, as variáveis DC, PAM, PaO², SaO², Vt, AaDO² diminuíram significativamente. Nenhuma alteração foi notada nos parâmetros FC e PaCO². As FiO² de 0,8 e 1,0 mostraram-se as mais indicadas por manter melhor estabilidade ventilatória e adequada troca gasosa.

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Section: Resultsunclassified

Diferentes frações inspiradas de oxigênio em coelhos hipovolêmicos anestesiados com propofol e submetidos à ventilação mecânica

et al. 2011

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“…anaesthetics, such as propofol, but is delayed by opioids, such as alfentanil. 12 Fourth ventricle idazoxan, an α 2 ‐adrenoceptor antagonist, could completely reverse phase II of the response to simulated haemorrhage or, alternatively, prevent its onset.…”

Section: Discussionmentioning

confidence: 99%

“… 13 When CI had fallen to 33% of its baseline level or MAP had fallen to 40 mmHg, whichever occurred first, CI was maintained constant for a further 5 min prior to deflation of the IVC cuff. The SVCI response to IVC cuff inflation is reported in preference to vascular resistance, because previous studies 11–13 have found a linear relationship between CI and SVCI, in contrast with vascular resistance. The vascular response to IVC cuff inflation was also found to be similar to the response to actual acute blood loss in the rabbit.…”

Section: Methodsmentioning

confidence: 99%

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Dexmedetomidine And Haemodynamic Responses To Acute Central Hypovolaemia In Conscious Rabbits

Ludbrook

Leeuwen

2000

Clin Exp Pharma Physio

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1. Effects of the alpha2-adrenoceptor agonist dexmedetomidine on vasoconstrictor and heart rate (HR) responses to acute central hypovolaemia were studied in eight chronically instrumented rabbits. We compared intravenous (i.v.) and fourth ventricular (V4) dexmedetomidine (0.1-10 microg/kg) and the reversal of effects by the alpha2-adrenoceptor antagonist idazoxan and the opioid agonist alfentanil. 2. Gradual inflation of an inferior vena cava (IVC) cuff reduced cardiac index (CI) by 8%/min, with progressive vasoconstriction and increased HR. In control rabbits, at approximately 40% baseline CI, there was sudden decompensation with failure of vasoconstriction and a fall in mean arterial pressure (MAP). 3. Dexmedetomidine (i.v. and V4) reduced resting MAP and HR and caused an earlier decompensation during central hypovolaemia. Intravenous dexmedetomidine (3 and 10 microg/kg) also reduced the slope of the initial vasoconstrictor response and the maximum HR. 4. The effects of dexmedetomidine were reversed by the antagonist idazoxan, which prevented the decompensation phase. Intravenous alfentanil was also effective in restoring the vasoconstrictor response and delaying decompensation with hypovolaemia after dexmedetomidine. Combining dexmedetomidine with an opioid, such as alfentanil, may provide the benefit of reduced sympathetic tone without increased risk of cardiovascular collapse.

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“…The absence of adverse cardiovascular effects from FLU are consistent with previous studies in rabbits. 8,45 Midazolam has a direct effect on contractility and systemic vascular resistance, potentially explaining the slow decrease in MAP over time in both treatment groups. 47 The sedation scale used in this study was adapted from a validated canine sedation scale.…”

Section: Midazolam Alone (N = 13)mentioning

confidence: 99%

A Pharmacokinetic-Pharmacodynamic Study of Intravenous Midazolam and Flumazenil in Adult New Zealand White—Californian Rabbits (Oryctolagus cuniculus)

Rousseau-Blass

Cribb

Beaudry

et al. 2021

j am assoc lab anim sci

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Flumazenil, a competitive GABAAreceptor antagonist, is commonly used in rabbits to shorten sedation or postanestheticrecovery after benzodiazepine administration. However, no combined pharmacokinetic (PK) and pharmacodynamic (PD)data are available to guide its administration in this species. In a prospective, randomized, blinded, crossover study design,the efficacy of IV flumazenil (FLU; 0.05 mg/kg) or saline control (SAL; equal volume) to reverse the loss of righting reflex(LORR) induced by IV midazolam (1.2 mg/kg) was investigated in 15 New Zealand white rabbits (2.73 to 4.65 kg, 1 y old). Rabbits were instrumented with arterial (central auricular artery) and venous (marginal auricular vein) catheters. Afterbaseline blood sampling, IV midazolam was injected (T0). Flumazenil or saline (FLU/SAL) was injected 30 s after LORR.Arterial blood samples were collected at 1 and 3 min after midazolam injection, and at 1, 3, 6, 10, 15, 21, 28, 36, 45 and 60 min after injection with flumazenil. Plasma samples for midazolam, 1-OH-midazolam and flumazenil were analyzed using high performance liquid chromatography-high-resolution mass spectrometry and the time to return of righting reflex (ReRR) was compared between groups (Wilcoxon test). FLU terminal half-life, plasma clearance and volume of distribution were 26.3min [95%CI: 23.3 to 29.3], 18.74 mL/min/kg [16.47 to 21.00] and 0.63 L/kg [0.55 to 0.71], respectively. ReRR was 25 times faster in rabbits treated with FLU (23 [8 to 44] s) compared with SAL (576 [130 to 1141] s; 95%CI [425 to 914 s]). Return of sedation(lateral recumbency) occurred in both groups (7/13 in FLU; 12/13 in SAL) with return of LORR in a few animals (4/13 in FLU; 7/13 in SAL) at 1540 [858 to 2328] s. In the population and anesthesia protocol studied, flumazenil quickly and reliably reversed sedation induced by midazolam injection. However, the potential return of sedation after flumazenil administration warrants careful monitoring in the recovery period.

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Haemodynamic response to simulated haemorrhage in the rabbit: interaction of i.v. anaesthesia and hypoxia

Cited by 6 publications

References 19 publications

Diferentes frações inspiradas de oxigênio em coelhos hipovolêmicos anestesiados com propofol e submetidos à ventilação mecânica

Diferentes frações inspiradas de oxigênio em coelhos hipovolêmicos anestesiados com propofol e submetidos à ventilação mecânica

Dexmedetomidine And Haemodynamic Responses To Acute Central Hypovolaemia In Conscious Rabbits

A Pharmacokinetic-Pharmacodynamic Study of Intravenous Midazolam and Flumazenil in Adult New Zealand White—Californian Rabbits (Oryctolagus cuniculus)

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