Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942003000500008
Brazilian Journal of Anesthesiology
Scientific Article

Efeitos da clonidina nas respostas cardiovasculares ao pinçamento aórtico infra-renal: estudo experimental no cão

Effects of clonidine on cardiovascular responses to infrarenal aortic cross-clamping: experimental study in dogs

Renato Viccário Achôa; Luiz Antonio Vane; José Reinaldo Cerqueira Braz

http://dx.doi.org/10.1590/S0034-70942003000500008 Braz J Anesthesiol, vol.53, n5, p.610-622, 2003
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Resumo

JUSTIFICATIVA E OBJETIVOS: O pinçamento aórtico infra-renal pode determinar alterações cardiovasculares. A clonidina, um alfa2-agonista, determina bradicardia e diminuição da pressão arterial. O objetivo do estudo foi avaliar os efeitos da clonidina sobre a função cardiovascular, em cães submetidos a pinçamento aórtico infra-renal. MÉTODO: O estudo aleatório foi realizado em 16 cães, distribuídos em dois grupos: G Controle - sem a utilização de clonidina e G Clon - clonidina, na dose inicial de 5 µg.kg-1, por via venosa, imediatamente antes do pinçamento aórtico infra-renal, seguido de 2 µg.min-1.m² até o final do estudo. Em todos os animais foi realizada ligadura infra-renal da aorta, por 45 minutos. Os atributos hemodinâmicos foram estudados nos momentos C (controle), após 10 (Ao10) e 25 (Ao25) minutos do pinçamento aórtico, e após 10 (DAo10) e 25 (DAo25) minutos do despinçamento aórtico. RESULTADOS: Durante o pinçamento aórtico, houve diferença significante entre os grupos, em relação à freqüência cardíaca, pressão arterial média e índice cardíaco (G Controle > G Clon). Após o despinçamento aórtico houve diferença significante entre os grupos, em relação à freqüência cardíaca (G Controle > G Clon) e pressões do átrio direito e da artéria pulmonar ocluída (G Clon > G Controle). Durante o pinçamento aórtico, houve nos dois grupos, aumento significante das pressões de átrio direito e artéria pulmonar ocluída, dos índices sistólico e do trabalho sistólico do ventrículo esquerdo, e diminuição do índice de resistência vascular pulmonar. No grupo controle houve aumento significante das pressões arterial média e da artéria pulmonar, e dos índices cardíaco e do trabalho sistólico do ventrículo direito. No grupo clonidina, houve diminuição significante da freqüência cardíaca. Após o despinçamento aórtico, houve nos dois grupos: diminuição significante da freqüência cardíaca e pressão arterial média, enquanto os valores das pressões do átrio direito e índice sistólico continuaram elevados. No grupo controle, os valores do índice de trabalho sistólico do ventrículo direito continuaram elevados enquanto os valores do índice cardíaco retornaram a valores próximos aos do controle. No grupo clonidina, os valores das pressões do átrio direito e da artéria pulmonar ocluída, e o índice sistólico, continuaram significantemente elevados. CONCLUSÕES: No cão, nas condições experimentais empregadas, a administração venosa contínua de clonidina atenua as respostas cardiovasculares decorrentes do pinçamento aórtico infra-renal.

Palavras-chave

ANIMAL, CIRURGIA, CIRURGIA, DROGAS, DROGAS, HEMODINÂMICA

Abstract

BACKGROUND AND OBJECTIVES: Infrarenal aortic cross-clamping is associated to cardiovascular effects. Clonidine, an alpha2-agonist, determines bradycardia and hypotension. This study aimed at analyzing the effects of clonidine on the cardiovascular function of dogs submitted to infrarenal aortic cross-clamping. METHODS: This randomized study involved 16 mixed breed dogs randomly distributed in two groups: G Control - no clonidine; and G Clon - clonidine (5 µg.kg-1) immediately before aortic cross-clamping, followed by 2 µg.min-1.m² until the end of the study. All dogs were submitted to infrarenal aortic cross-clamping during 45 minutes. Hemodynamic parameters were measured at control (C), 10 (Ao10) and 25 (Ao25) minutes after aortic cross-clamping, and 10 (DAo10) and 25 (DAo25) minutes after aortic unclamping. RESULTS: There were significant differences between groups in heart rate, mean blood pressure and cardiac index (G control > G Clon) during aortic cross-clamping. After aortic unclamping there were significant differences between groups in heart rate (G Control > G Clon), and right atrium and pulmonary capillary wedge pressures (G Clon > G Control). During aortic cross-clamping both groups have shown significant increase in right atrium pressure, pulmonary capillary wedge pressure, stroke volume index and left ventricular systolic work index, and significant decrease in pulmonary vascular resistance index. There has been significant increase in mean blood pressure, pulmonary artery pressure, cardiac index and right ventricular systolic work index in the G Control. The clonidine group has shown significant heart rate decrease. After aortic unclamping, both groups have shown significant heart rate and mean blood pressure decrease, while right atrium pressure and stroke volume index remained high. Right ventricular systolic work index remained high in the control group, while cardiac index values returned to close to baseline values. In the clonidine group, right atrium pressure, pulmonary wedge pressure and systolic index remained significantly high. CONCLUSIONS: In dogs under our experimental conditions, continuous intravenous clonidine has attenuated cardiovascular responses to infrarenal aortic cross-clamping.

Keywords

ANIMAL, DRUGS, DRUGS, HEMODYNAMICS, SURGERY, SURGERY

References

Jackson B. Surgery of Adquired Vascular Disorders: Aneurysms. 1969:43.

Bickerstaff LK, Hollier LH, Van Pennen HJ. Abdominal aortic aneurysms: the changing natural history. J Vasc Surg. 1984;1:6-8.

Gelman S. The pathophysiology of aortic cross-clamping and unclamping. Anesthesiology. 1995;82:1026-1060.

Blankenstijn JD, Lindenburg FP, Vander Graaf Y. Influence of study design on reported mortality and morbidity rates after abdominal aortic aneurysm repair. Br J Surg. 1998;85:1624-1630.

Baxendale BR, Baker DM, Hutchinson A. Haemodynamic and metabolic response to endovascular repair of infra-renal aortic aneurysms. Br J Anaesth. 1996;77:581-585.

Cunningham AJ. Anaesthesia for Repair of Abdominal Aortic Aneurysms. Recent Advances in Anaesthesia and Analgesia. 1992:49-69.

Roisen MF, Beaupre PN, Alpert RA. Monitoring with two-dimensional transesophageal echocardiography: Comparison of myocardial function in patients undergoing supra-celiac, suprarenal-infraceliac, or infrarenal aortic occlusion. J Vasc Surg. 1984;1:300-305.

Seeman-Lodding H, Biber B, Martner J. Cardiovascular responses to experimental infra-renal aortic cross-clamping: Modulating effects of isoflurane, sodium nitroprusside and milrinone. Acta Anaesthesiol Scand. 1996;40:408-415.

Clark NJ, Stanley TH. Anesthesia for Vascular Surgery. Anesthesia. 1994:1851-1895.

Braz JRC. Anestesia para Cirurgia da Aorta Abdominal. O Sistema Cardiovascular e a Anestesia. 1997:221-236.

Quintin L, Bonnet F, Macquin I. Aortic surgery: effect of clonidine on intraoperative catecholamine and circulatory stability. Acta Anaesthesiol Scand. 1990;34:132-137.

Quintin L, Bouilloc X, Butin E. Clonidine for major vascular surgery in hypertensive patients: a double-blind, controlled, randomized study. Anesth Analg. 1996;83:687-695.

Quintin L, Roudot F, Roux C. Effect of clonidine on the circulation and vasoactive hormones after aortic surgery. Br J Anaesth. 1991;66:108-115.

Morrison DF. Multivariate Statistical Methods. 1967:338.

Bisinotto FMB. Comparação dos efeitos do halotano, isoflurano e sevoflurano sobre as funções cardiovascular, renal e de oxigenação em cães sob pinçamento aórtico infra-renal. :216.

Harpole DH, Clements FM, Quill T. Right and left ventricular performance during and after abdominal aortic aneurysm repair. Ann Surg. 1989;209:356-362.

MacMillan LB, Hein L, Smith MS. Central hypotensive effects of the alpha (2a)-adrenergic receptor subtype. Science. 1996;273:801-803.

McCallum JB, Boban N, Hogan Q. The mechanism of alpha2-adrenergic inhibition of sympathetic ganglionic transmission. Anesth Analg. 1998;87:503-510.

Reds DJ, Regunathan S, Meely MP. Imidazoline receptors and clonidine displacing substance in relationship to control of blood pressure, neuroprotection and adrenomedullary secretion. Am J Hypertens. 1992;5:51S-55S.

Gelman S, Curtis SE, Bradley WE. Angiotensin and adrenoreceptors role in hemodynamic response to aortic cross-clamping. Am J Physiol. 1993;264:H14-H20.

Berkowitz HD, Shetty S. Renin release and renal cortical ischaemia following aortic cross clamping. Arch Surg. 1974;109:612-616.

Kataja J, Kaukinen S, Viinamaki O. Hemodynamic and hormonal changes in patients pretreated with captopril for surgery of abdominal aorta. J Cardiovasc Anesth. 1989;3:425-432.

Ryan T, Mannion D, O’Brien W. Spinal cord perfusion pressure in dogs after control of proximal aortic hypertension during thoracic aortic cross-clamping with esmolol or sodium nitroprusside. Anesthesiology. 1993;78:317-325.

Myles PS, Hunt JO, Holdgaard HO. Clonidine and cardiac surgery: haemodynamic and metabolic effects on myocardial ischaemia and recovery. Anaesth Intensive Care. 1999;27:137-147.

Talk P, Chen R, Thomas R. The hemodynamic and adrenergic effects of perioperative dexmedetomidine infusion after vascular surgery. Anesth Analg. 2000;90:834-839.

Flack JW, Bloor BC, Flack WE. Reduced narcotic requirements by clonidine with improved hemodynamic and adrenergic stability in patient undergoing coronary surgery. Anesthesiology. 1987;67:11-19.

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