The effects of 2 levels of the inspired oxygen fraction on blood gas variables in propofol-anesthetized dogs with high intracranial pressure

The influence of 2 different levels of the inspired oxygen fraction (FiO(2)) on blood gas variables was evaluated in dogs with high intracranial pressure (ICP) during propofol anesthesia (induction followed by a continuous rate infusion [CRI] of 0.6 mg/kg/min) and intermittent positive pressure ventilation (IPPV). Eight adult mongrel dogs were anesthetized on 2 occasions, 21 d apart, and received oxygen at an FiO(2) of 1.0 (G100) or 0.6 (G60) in a randomized crossover fashion. A fiberoptic catheter was implanted on the surface of the right cerebral cortex for assessment of the ICP. An increase in the ICP was induced by temporary ligation of the jugular vein 50 min after induction of anesthesia and immediately after baseline measurement of the ICP. Blood gas measurements were taken 20 min later and then at 15-min intervals for 1 h. Numerical data were submitted to Morrison's multivariate statistical methods. The ICP, the cerebral perfusion pressure and the mean arterial pressure did not differ significantly between FiO(2) levels or measurement times after jugular ligation. The only blood gas values that differed significantly (P < 0.05) were the arterial oxygen partial pressure, which was greater with G100 than with G60 throughout the procedure, and the venous haemoglobin saturation, that was greater with G100 than with G60 at M0. There were no significant differences between FiO(2) levels or measurement times in the following blood gas variables: arterial carbon dioxide partial pressure, arterial hemoglobin saturation, base deficit, bicarbonate concentration, pH, venous oxygen partial pressure, venous carbon dioxide partial pressure and the arterial-to-end-tidal carbon dioxide difference.

Bispectral index in dogs with high intracranial pressure, anesthetized with propofol and submitted to two levels of FiO2

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Combinations of low doses of unfractionated heparin and of low-molecular-weight heparin prevent experimental venous thrombosis

Synergism between low-molecular-weight heparin and low doses of unfractionated heparin (UH) enhancing anti-factor Xa activity and the release of tissue factor pathway inhibitor was observed. The aim of this study was to verify whether this association is effective in preventing experimental venous thrombosis. Seventy rats were allocated into 7 groups: the control group treated with distilled water, the H-350 group treated with UH 350 IU/kg, the E-2 group treated with enoxaparin 2 mg/kg, the H-175 group treated with UH 175 IU/kg, the E-1 group treated with enoxaparin 1 mg/kg, the H-175 + E-1 group treated with UH 175 IU/kg plus enoxaparin 1 mg/kg, and the H-100 + E-0.5 group treated with UH 100 IU/kg plus enoxaparin 0.5 mg/kg. Forty minutes after subcutaneous injection, thrombosis was induced in vena cava. Three hours later, if present, thrombi were withdrawn and weighed. Bleeding time, activated partial thromboplastin time, thrombin time (TT), and anti-factor Xa were measured at the beginning and end of the experiment. Fortyeight other animals were treated, but without inducing thrombus, and tests were performed 40 min after injection. Thrombus developed in 90.9% of control animals, 20% of the H-350 group, 22.2% of the E-2 group, 10% of the H-175 + E-1 group, and 30% of the H-100 + E-0.5 group; there was a difference between group C and the other groups. Only in the H-350 and H-175 + E-1 groups were TT and activated partial thromboplastin time prolonged in relation to control at the end of the experiment. Forty minutes after injection, TT was prolonged in the H-350 and H-175 + E-1 groups. In conclusion, combinations of low doses of low-molecular-weight heparin and low doses of UH were as effective as high doses of each one used alone in preventing thrombus development in rat vena cava. Copyright (c) 2005 S. Karger AG, Basel.

Prophylaxis of deep-vein thrombosis after lower extremity amputation: Comparison of low molecular weight heparin with unfractionated heparin

OBJETIVO: Comparar a eficácia e segurança da profilaxia com heparina de baixo peso molecular (enoxaparina) versus heparina não fracionada (HNF). MÉTODOS: Setenta e cinco pacientes (59 homens e 16 mulheres ), submetidos a amputação maior dos membros inferiores (30 acima do joelho e 45 abaixo do joelho ), foram tratados ao acaso com HNF subcutânea (5,000 IU -2x/dia ) ou enoxaparina subcutânea (40mg/dia ) durante a hospitalização . A profilaxia teve início 12 horas antes da cirurgia ou , em casos emergenciais , no primeiro dia de pós-operatório. RESULTADOS: Os dois grupos de tratamento foram comparáveis em termos de características gerais . A avaliação da TVP foi feita por meio de exame clínico diário e pelo mapeamento dúplex antes e 5-8 dias após a cirurgia . A TVP foi documentada no lado operado em 9,75% dos pacientes tratados com enoxaparina e em 11,76% dos pacientes tratados com HNF (p=0,92) e houve um caso de TVP bilateral em cada grupo . Sangramentos não foram verificados nos 2 grupos . CONCLUSÃO: A enoxaparina e HNF foram igualmente eficientes e seguras para a profilaxia da TVP em pacientes submetidos à amputação de membros inferiores .

Prevalence of deep vein thrombosis and pulmonary embolism in superficial thrombophlebitis of the lower limbs: prospective study of 60 cases

Aim. Superficial thrombophlebitis (ST) ascending the lower limbs is a common disease, which may be associated with deep vein thrombosis (DVT) and pulmonary embolism (PE). The aim of this study was to investigate the prevalence of DVT and PE as complications of ascending ST of the lower limbs in the great saphenous vein (GSV) or SSV (SSV) and probable risk factors.Methods. For this study 60 consecutive patients were enrolled with ascending ST of the GSV or SSV, seen between 2000 and 2003 at a public hospital in Botucatu, SP, Brazil. All patients were assessed clinically, by venous Duplex scanning of the lower limbs to confirm ST and test for DVT, and by means of pulmonary scintigraphy to test for PE.Results. In 13 ST cases (21.67%) there was concomitant DVT and 17 ST patients (28.33%) also had PE. Eleven patients had a clinical status suggestive of DVT, but only in eight of these (61.5%), this clinical diagnosis was confirmed. Fourteen patients had a clinical status suggestive of PE, and this diagnosis was confirmed in six cases (35.30%). ST patients who also had DVT and/or PE were given anticoagulant treatment with heparin and warfarin. None of the variables studied was predictive of DVT or PE (P>0.05). However, the presence of varicose veins reduced the risk of patients having DVT (relative risk=9.09; 95%CI:1.75 - 50.00 and P=0.023).Conclusion. The prevalence rates of PE (28.3%) and DVT (21.6%) were elevated in this sample of ascending ST cases, indicating a need for detailed assessment of patients for signs of these complications, including for therapeutic management decision making. [Int Angiol 2009;28:400-8]

Advances in ultrasound techniques improve early detection of deep vein thrombosis

Aim. This study aimed at assessing the accuracy of ultrasound (US) in the diagnosis of recent deep vein thrombosis (DVT) in an experimental study in dogs.Methods. Design: blinded and randomized experimental study. Twenty dogs were randomly divided in two groups: control group (CG) and thrombosis group (TG). US was performed in the pre- and postoperative period. Phlebography was performed immediately prior to the postoperative US. After the second US, a surgery was performed to detect whether thrombus was present or not. US results were compared to those of phlebography and surgical findings.Results. in all dogs, inferior vena cava (IVC) was compressible. The relations of IVC diameter with the aorta were higher (P<0.005) in TG than in CG. Spectral Doppler in spontaneous breathing, tissue harmonic imaging, power Doppler and B flow showed sensitivity, specificity and accuracy of 1. Phlebography presented sensitivity of 90%, specificity of 80% and accuracy of 85%, when compared to surgical finding.Conclusion. For the diagnosis of recent DVT in the experimental model used, venous compressibility proved to be inefficient. The ratio of WC diameter to aorta, when increased, suggests thrombosis. The use of new US technological advances increases accuracy. Phlebography was less accurate than US.

Complicações da terapia anticoagulante com warfarina em pacientes com doença vascular periférica: estudo coorte prospectivo

OBJETIVO: Estudar prospectivamente a freqüência de complicações em pacientes tratados com warfarina e acompanhados no Ambulatório de Anticoagulação da Faculdade de Medicina de Botucatu da Universidade Estadual Paulista. MÉTODOS: Pacientes sorteados entre os agendados para consulta de junho de 2002 a fevereiro de 2004. Na primeira consulta, foi preenchida ficha com dados de identificação e clínicos. A cada retorno, ou quando o paciente procurou o hospital por intercorrência, foi preenchida ficha com a razão normatizada internacional, existência e tipo de intercorrência e condições de uso dos antagonistas da vitamina K. RESULTADOS: Foram acompanhados 136 pacientes (61 homens e 75 mulheres), 99 com tromboembolismo venoso e 37 com doença arterial; 59 pacientes eram de Botucatu, e 77, de outros municípios. Foram registradas 30 intercorrências: nove não relacionadas ao uso da warfarina e 21 complicações hemorrágicas (38,8 por 100 pacientes/ano). Uma hematêmese foi considerada grave (1,9 por 100 pacientes/ano). As demais foram consideradas moderadas ou leves. Não houve óbitos, hemorragia intracraniana ou necrose cutânea. A única associação significante foi da freqüência de hemorragia com nível médio de razão normatizada internacional. CONCLUSÃO: Nossos resultados mostram a viabilidade desse tratamento em pacientes vasculares em nosso meio, mesmo em população de baixo nível socioeconômico, quando tratados em ambulatório especializado.

Antithrombotic effect of Lonomia obliqua caterpillar bristle extract on experimental venous thrombosis

The venom of Lonomia obliqua caterpillar may induce a hemorrhagic syndrome in humans, and blood incoagulability by afibrinogenemia when intravenously injected in laboratory animals. The possible antithrombotic and thrombolytic activities of L. obliqua caterpillar bristle extract (LOCBE) were evaluated in this study. The minimal intravenous dose of the extract necessary to induce afibrinogenemia and anticoagulation was 3.0 and 10.0 µg protein/kg body weight for rabbits and rats, respectively. In rabbits, this dose induced total blood incoagulability for at least 10 h and did not reduce the weight of preformed venous thrombi, in contrast to streptokinase (30,000 IU/kg). In rats, pretreatment with 5.0 and 10.0 µg/kg LOCBE prevented the formation of thrombi induced by venous stasis or by injury to the venous endothelium. The dose of 5.0 µg/kg LOCBE did not modify blood coagulation assay parameters but increased bleeding time and decreased plasma factor XIII concentration. When the extract was administered to rats at the dose of 10.0 µg/kg, the blood was totally incoagulable for 6 h. These data show that LOCBE was effective in preventing experimental venous thrombosis in rats, justifying further studies using purified fractions of the extract to clarify the mechanisms of this effect.

Intracranial variables in propofol or sevoflurane-anesthestized dogs subjected to subarachnoid administration of iohexol

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