Acute normovolemic hemodilution (ANH) has been proposed to decrease the need for allogenic blood transfusion. Consequently, great amounts of fluids are necessary to maintain hemodynamics during and after blood removal. The aim of this experiment was to evaluate the oxygenation, respiratory compliance, and lung structure during ANH performed with lactated Ringer's solution and hydroxyethyl starch (HES). Gas exchange, extravascular lung water, intrathoracic blood volume, serum osmolality, respiratory mechanics, and optical and electronic microscopy of lung biopsies were evaluated. Animals were randomized into three groups: CTL (control, n = 9), HES (HES 6% 200/0.5, n = 9), and LR (lactated Ringer's solution, n = 9). Animals in groups HES and LR underwent ANH to reach a preestablished hematocrit of around 15%. The removed blood was replaced with HES in a proportion of 1:1 and with lactated Ringer's solution 3:1. The LR group demonstrated a tendency for a marked time-dependence decrease in compliance (P = 0.013 in T2; P = 0.008 in T3) and in Pao2/fraction of inspired oxygen (Fio2) ratio (P = 0.033 in T2) as well as an increase in (A-a) Grad O2 (P = 0.037 in T2). Extravascular lung water and intrathoracic blood volume did not present any significant variation among the groups. In contrast, serum osmolality presented a significant decline in animals hemodiluted with lactated Ringer's solution. Optical and electronic microscopy of lungs biopsies revealed moderate to serious collapses and basement membrane enlargement in LR group. In this kind of experimental model, ANH with 6% HES (200/0.5) seems to preserve lung structure better as evidenced by maintenance of oxygenation indexes and respiratory compliance when compared with that in the Ringer's solution hemodiluted group.

216Pesq. Vet. Bras. 28(4):216-222, abril 2008 RESUMO.-[Anestesia total intravenosa com propofolquetamina racêmica e propofol quetamina-S: estudo comparativo e avaliação hemodinâmica em cães submetidos à ovariohisterectomia.] A anestesia total intravenosa (TIVA) com propofol e quetamina proporciona um efeito muito satisfatório do ponto de vista clínico. Este estudo, cego e randomizado, comparou a indução e manutenção da anestesia com infusão contínua de propofolquetamina racêmica (PRK) e propofol-quetamina-S (PSK) em cães, e avaliou seus efeitos hemodinâmicos, metabó-licos e ventilatórios. Foram avaliadas sete cadelas em cada grupo, submetidas à ovariohisterectomia. A anestesia foi induzida no Grupo PRK, com propofol (4.0mg kg -1 ) e cetamina (2.0mg kg -1 ) por via intravenosa (i.v.), seguida de infusão contínua de propofol (dose inicial de 0.5mg kg -1 min -1 ) e cetamina racêmica(0.2mg kg -1 min -1 ) i.v. No Grupo PSK, a indução anestésica foi com propofol (4.0mg kg -1 ) e cetamina-S (1.0 mg kg -1 ) i.v., seguida de infusão contínua de propofol (dose inicial de 0,5mg kg -1 min -1 ) e Total intravenous anaesthesia (TIVA) with propofol and ketamine proved to be very satisfactory from a clinical point of view. This blind randomised controlled trial was designed to compare induction and maintenance of anaesthesia under continuous infusion of propofol-racemic ketamine (PRK) with that of propofol-S-ketamine (PSK) and evaluate their haemodynamic, metabolic and ventilatory effects. Seven female dogs undergoing ovariohysterectomy were involved in each group. Anaesthesia was induced: in Group PRK, with propofol (4.0mg kg -1 ) and racemic ketamine (2.0mg kg -1 ) intravenous (i.v.), followed by i.v. infusion of propofol (initial dose of 0.5mg kg -1 min -1 ) and racemic ketamine (0.2mg kg -1 min -1 ); in Group PSK, with propofol (4.0mg kg -1 ) and S-ketamine (1.0 mg kg 1 ) i.v., followed by i.v. infusion of propofol (initial dose of 0.5mg kg -1 min -1 ) and S-ketamine (0.1mg kg -1 min -1 ). Parameters were assessed before anaesthesia and in 6 time points after induction. In both groups, heart rate increased significantly at all time points. There was a slight decrease in systemic blood pressure, cardiac output and cardiac index in both groups. The systolic index decrease significantly and intense respiratory depression was observed in all groups, making assisted ventilation necessary. Total intravenous anaesthesia with propofol-racemic ketamine and propofol-S-ketamine 217 cetamina-S ( 0.1mg kg -1 min -1 ) i.v. Os parâmetros foram observados antes da anestesia e em seis momentos após a indução anestésica. Em ambos os grupos, a freqüência cardíaca elevouse significantemente em todos os momentos. Houve pequena redução na pressão arterial sistêmica, débito cardíaco e índice cardíaco. O índice sistólico apresentou redução significante e houve intensa depressão respirató-ria em ambos os grupos. A anestesia total intravenosa com a associação do propofol à cetamina racêmica ou à cetamina-S proporciona boa estabilidade hemodinâmic...

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