Ultrassonografia da veia cava inferior na avaliação do volume intravascular e fluido-responsividade em pacientes críticos: uma revisão sistemática / Inferior vena cava ultrasound for assessing volume status and fluid responsiveness in critically ill patients: a systematic review

Fundamento: A avaliação do volume intravascular e da fluido-responsividade é uma condição desafiadora no manejo de pacientes críticos. Os métodos diagnósticos precisam garantir segurança, reprodutibilidade e praticidade no monitoramento hemodinâmico. Objetivo: Descrever a aplicabilidade dos índices ultrassonográficos da veia cava inferior na avaliação do volume intravascular e na predição da fluido-responsividade em pacientes críticos. Método: Trata-se de revisão sistemática realizada por meio das bases de dados PubMed®, Lilacs e SciELO nos 5 anos anteriores. Os descritores utilizados foram "inferior vena cava", "ultrasonography", "fluid-responsiveness" e "volume status". Resultados: Foram selecionados 13 artigos compatíveis com os objetivos deste estudo. O índice de colapsibilidade da veia cava inferior variou de 25% a 50% como ponto de corte para definição de hipovolemia. Além disso, apresentou aplicabilidade na predição da fluido-responsividade em pacientes sob respiração espontânea, com pontos de corte variando de 25% a 57%. Em cenários de ventilação mecânica, o índice de distensibilidade da veia cava inferior mostrou-se mais eficaz, quando comparado às demais medidas, para predição de fluido-responsividade, mas foi encontrada variação de 10,2% a 20,5%. O índice diâmetro da veia cava inferior/diâmetro da artéria aorta foi especialmente útil na população pediátrica para definição do volume intravascular, mas em adultos existiram muitas divergências quanto à sua aplicabilidade. Conclusão: A avaliação do volume intravascular e da fluido-responsividade por meio dos índices ultrassonográficos da veia cava inferior apresenta aplicabilidade e segurança no diagnóstico e no monitoramento da instabilidade hemodinâmica. Entretanto, são necessários estudos de padronização de valores em razão das divergências quanto aos pontos de corte utilizados em cada índice.(AU)

Conservation of both hematocrit and liver regeneration in hepatectomies: a vascular occlusion approach in rats / Hepatectomia hemoconservadora no rato: preservação do hematócrito e da regeneração hepática

ABSTRACT Background: Hepatectomies promote considerable amount of blood loss and the need to administrate blood products, which are directly linked to higher morbimortality rates. The blood-conserving hepatectomy (BCH) is a modification of the selective vascular occlusion technique. It could be a surgical maneuver in order to avoid or to reduce the blood products utilization in the perioperative period. Aim: To evaluate in rats the BCH effects on the hematocrit (HT) variation, hemoglobin serum concentration (HB), and on liver regeneration. Methods: Twelve Wistar rats were divided into two groups: control (n=6) and intervention (n=6). The ones in the control group had their livers partially removed according to the Higgins and Anderson technique, while the rats in the treatment group were submitted to BCH technique. HT and HB levels were measured at day D0, D1 and D7. The rate between the liver and rat weights was calculated in D0 and D7. Liver regeneration was quantitatively and qualitatively evaluated. Results: The HT and HB levels were lower in the control group as of D1 onwards, reaching an 18% gap at D7 (p=0.01 and p=0.008, respectively); BCH resulted in the preservation of HT and HB levels to the intervention group rats. BCH did not alter liver regeneration in rats. Conclusion: The BCH led to beneficial effects over the postoperative HT and serum HB levels with no setbacks to liver regeneration. These data are the necessary proof of evidence for translational research into the surgical practice.

RESUMO Racional: As hepatectomias compreendem considerável perda sanguínea e utilização de hemoderivados, o que diretamente estão relacionados com maior morbimortalidade. A hepatectomia hemoconservadora (HH) é modificação da técnica de oclusão vascular seletiva em hepatectomia. Ela pode ser alternativa cirúrgica para evitar ou diminuir o uso de hemoderivados no perioperatório. Objetivo: Avaliar os efeitos da HH sobre o volume globular (VG), concentração de hemoglobina (HB) e sobre a regeneração hepática em ratos. Métodos: Dois grupos de ratos Wistar foram constituídos: controle (n=6) e intervenção (n=6). Os do grupo controle foram submetidos à hepatectomia parcial de Higgins e Anderson e os do grupo Intervenção à HH. VG e HB foram medidos nos dias D0, D1 e D7. A relação peso do fígado/peso do rato foi calculada em D0 e D7. A regeneração hepática foi analisada qualitativamente e quantitativamente. Resultados: Houve diminuição dos níveis de VG e HB nos ratos do grupo controle a partir de D1, atingindo decréscimo de 18% em D7 (p=0,01 e p=0,008 respectivamente); a HH permitiu a manutenção dos níveis de VG e HB nos ratos do grupo intervenção. A HH não alterou a regeneração hepática. Conclusão: HH resultou em níveis maiores de VG e HB pós-operatórios sem alterar a regeneração hepática. Pode-se considerar estes dados como a prova necessária para a translação à pesquisa clinicocirúrgica.

Serotoninergic Modulation of Basal Cardiovascular Responses and Responses Induced by Isotonic Extracellular Volume Expansion in Rats / Modulação Serotoninérgica de Respostas Cardiovasculares Basais e Induzidas pela Expansão Isotônica do Volume Extracelular em Ratos

Abstract Background: Isotonic blood volume expansion (BVE) induced alterations of sympathetic and parasympathetic activity in the heart and blood vessels, which can be modulated by serotonergic pathways. Objective: To evaluate the effect of saline or serotonergic agonist (DOI) administration in the hypothalamic paraventricular nucleus (PVN) on cardiovascular responses after BVE. Methods: We recorded pulsatile blood pressure through the femoral artery to obtain the mean arterial pressure (MAP), systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR) and the sympathetic-vagal ratio (LF/HF) of Wistar rats before and after they received bilateral microinjections of saline or DOI into the PVN, followed by BVE. Results: No significant differences were observed in the values of the studied variables in the different treatments from the control group. However, when animals are treated with DOI followed by BVE there is a significant increase in relation to the BE control group in all the studied variables: MBP (114.42±7.85 vs 101.34±9.17); SBP (147.23±14.31 vs 129.39±10.70); DBP (98.01 ±4.91 vs 87.31±8.61); HR (421.02±43.32 vs 356.35±41.99); and LF/HF ratio (2.32±0.80 vs 0.27±0.32). Discussion: The present study showed that the induction of isotonic BVE did not promote alterations in MAP, HR and LF/HF ratio. On the other hand, the injection of DOI into PVN of the hypothalamus followed by isotonic BVE resulted in a significant increase of all variables. Conclusion: These results suggest that serotonin induced a neuromodulation in the PVN level, which promotes an inhibition of the baroreflex response to BVE. Therefore, the present study suggests the involvement of the serotonergic system in the modulation of vagal reflex response at PVN in the normotensive rats.

Resumo Fundamento: Expansão de volume extracelular (EVEC) promove alterações da atividade simpática e parassimpática no coração e vasos sanguíneos, os quais podem ser moduladas por vias serotoninérgicas. Objetivo: Avaliar o efeito da administração de salina ou agonista serotoninérgico (DOI) nos núcleos paraventriculares hipotalâmico (NPV) sobre respostas cardiovasculares após EVEC. Métodos: Foram obtidos registros da pressão arterial pulsátil, por meio da artéria femoral, para obtenção dos valores da pressão arterial média (PAM), sistólica (PAS), diastólica (PAD), frequência cardíaca (FC) e razão simpático-vagal (LF/HF) de ratos Wistar antes e após receberem microinjeções bilaterais no NPV de salina ou DOI seguida de EVEC. Resultados: Não foram observadas diferenças significativas dos valores das variáveis estudadas nos diferentes tratamentos do grupo controle. Entretanto, quando os animais são tratados com DOI seguida de EVEC ocorre aumento significativo em relação ao grupo controle com EVEC em todas as variáveis estudadas: PAM (114,42±7,85 vs 101,34±9,17), PAS (147,23±14,31 vs 129,39±10,70), PAD (98,01 ±4,91 vs 87,31±8,61), FC (421,02±43,32 vs 356,35±41,99) e LF/HF (2,32±0,80 vs 0,27±0,32). Discussão: O presente estudo mostrou que a indução de EVEC isotônica não promoveu alterações na PAM, PAD, PAS, FC e LF/HF. Por outro lado, os animais que receberam microinjeção de DOI no NPV seguida de EVEC apresentaram aumento significativo de todas as variáveis. Conclusão: Esses resultados sugerem que a serotonina exerce uma neuromodulação em nivel do NPV, e essa promove uma inibição da resposta barorreflexa frente à EVEC. Assim, o presente trabalho sugere o envolvimento serotoninérgico na neuromodulação no nivel do NPV na resposta reflexa vagal em ratos normotensos.

Role of microRNAs 221/222 on Statin Induced Nitric Oxide Release in Human Endothelial Cells / Papel dos microRNAs 221/222 na Liberação de Óxido Nítrico Induzida por Estatinas em Células Endoteliais Humanas

Background: Nitric oxide (NO) has been largely associated with cardiovascular protection through improvement of endothelial function. Recently, new evidence about modulation of NO release by microRNAs (miRs) has been reported, which could be involved with statin-dependent pleiotropic effects, including anti-inflammatory properties related to vascular endothelium function. Objective: To evaluate the effects of cholesterol-lowering drugs including the inhibitors of cholesterol synthesis, atorvastatin and simvastatin, and the inhibitor of cholesterol absorption ezetimibe on NO release, NOS3 mRNA expression and miRs potentially involved in NO bioavailability. Methods: Human umbilical vein endothelial cells (HUVEC) were exposed to atorvastatin, simvastatin or ezetimibe (0 to 5.0 μM). Cells were submitted to total RNA extraction and relative quantification of NOS3 mRNA and miRs -221, -222 and -1303 by qPCR. NO release was measured in supernatants by ozone-chemiluminescence. Results: Both statins increased NO levels and NOS3 mRNA expression but no influence was observed for ezetimibe treatment. Atorvastatin, simvastatin and ezetimibe down-regulated the expression of miR-221, whereas miR-222 was reduced only after the atorvastatin treatment. The magnitude of the reduction of miR-221 and miR-222 after treatment with statins correlated with the increment in NOS3 mRNA levels. No influence was observed on the miR-1303 expression after treatments. Conclusion: NO release in endothelial cells is increased by statins but not by the inhibitor of cholesterol absorption, ezetimibe. Our results provide new evidence about the participation of regulatory miRs 221/222 on NO release induction mediated by statins. Although ezetimibe did not modulate NO levels, the down-regulation of miR-221 could involve potential effects on endothelial function. .

Fundamento: O óxido nítrico (NO) tem sido amplamente associado com proteção cardiovascular através de melhoria da função endotelial. Recentemente, novas evidências sobre a modulação do NO na liberação de microRNAs (miRs) têm sido relatadas, o que poderia estar envolvido com efeitos pleiotrópicos dependentes de estatinas, incluindo propriedades anti-inflamatórias relacionadas com a função do endotélio vascular. Objetivo: Avaliar os efeitos dos medicamentos redutores de colesterol, incluindo os inibidores da síntese de colesterol, atorvastatina e sinvastatina, e o inibidor da absorção de colesterol, ezetimiba, na liberação de NO, expressão do mRNA do NOS3 e miRs potencialmente envolvidos na biodisponibilidade do NO. Métodos: Células endoteliais da veia umbilical humana (HUVEC) foram expostas à atorvastatina, sinvastatina ou ezetimiba (0 a 5,0 μM). As células foram submetidas à extração do RNA total e quantificação relativa de mRNA do NOS3 e dos miRs-221,-222 e -1303 por qPCR. A liberação de NO foi medida em sobrenadantes por ozônio-quimioluminescência. Resultados: Ambas as estatinas aumentaram os níveis de NO e a expressão do mRNA do NOS3, mas nenhum efeito foi observado em relação ao tratamento com ezetimiba. A atorvastatina, sinvastatina e ezetimiba regularam negativamente a expressão do miR-221, enquanto que o miR-222 reduziu somente após o tratamento com atorvastatina. A magnitude da redução de miR-221 e miR-222 após tratamento com estatinas correlacionou com o incremento nos níveis de mRNA do NOS3. Nenhuma influência foi observada sobre a expressão do miR-1303 após os tratamentos. Conclusão: A liberação de NO pelas células endoteliais é aumentada por estatinas, mas não pelo inibidor da absorção de colesterol ezetimiba. Nossos resultados fornecem novas evidências sobre a participação dos miRs regulatórios 221/222 na liberação de NO mediada por estatinas. Embora a ezetimiba não tenha modulado os níveis de NO, a regulação negativa ...

Intercostal and forearm muscle deoxygenation during respiratory fatigue in patients with heart failure: potential role of a respiratory muscle metaboreflex

The purpose of this study was to determine the effect of respiratory muscle fatigue on intercostal and forearm muscle perfusion and oxygenation in patients with heart failure. Five clinically stable heart failure patients with respiratory muscle weakness (age, 66±12 years; left ventricle ejection fraction, 34±3%) and nine matched healthy controls underwent a respiratory muscle fatigue protocol, breathing against a fixed resistance at 60% of their maximal inspiratory pressure for as long as they could sustain the predetermined inspiratory pressure. Intercostal and forearm muscle blood volume and oxygenation were continuously monitored by near-infrared spectroscopy with transducers placed on the seventh left intercostal space and the left forearm. Data were compared by two-way ANOVA and Bonferroni correction. Respiratory fatigue occurred at 5.1±1.3 min in heart failure patients and at 9.3±1.4 min in controls (P<0.05), but perceived effort, changes in heart rate, and in systolic blood pressure were similar between groups (P>0.05). Respiratory fatigue in heart failure reduced intercostal and forearm muscle blood volume (P<0.05) along with decreased tissue oxygenation both in intercostal (heart failure, -2.6±1.6%; controls, +1.6±0.5%; P<0.05) and in forearm muscles (heart failure, -4.5±0.5%; controls, +0.5±0.8%; P<0.05). These results suggest that respiratory fatigue in patients with heart failure causes an oxygen demand/delivery mismatch in respiratory muscles, probably leading to a reflex reduction in peripheral limb muscle perfusion, featuring a respiratory metaboreflex.

Fluid distribution kinetics during cardiopulmonary bypass

OBJECTIVE: The purpose of this study was to examine the isovolumetric distribution kinetics of crystalloid fluid during cardiopulmonary bypass. METHODS: Ten patients undergoing coronary artery bypass grafting participated in this prospective observational study. The blood hemoglobin and the serum albumin and sodium concentrations were measured repeatedly during the distribution of priming solution (Ringer's acetate 1470 ml and mannitol 15% 200 ml) and initial cardioplegia. The rate of crystalloid fluid distribution was calculated based on 3-min Hb changes. The preoperative blood volume was extrapolated from the marked hemodilution occurring during the onset of cardiopulmonary bypass. Clinicaltrials.gov: NCT01115166. RESULTS: The distribution half-time of Ringer's acetate averaged 8 minutes, corresponding to a transcapillary escape rate of 0.38 ml/kg/min. The intravascular albumin mass increased by 5.4% according to mass balance calculations. The preoperative blood volume, as extrapolated from the drop in hemoglobin concentration by 32% (mean) at the beginning of cardiopulmonary bypass, was 0.6-1.2 L less than that estimated by anthropometric methods (p<0.02). The mass balance of sodium indicated a translocation from the intracellular to the extracellular fluid space in 8 of the 10 patients, with a median volume of 236 ml. CONCLUSIONS: The distribution half-time of Ringer's solution during isovolumetric cardiopulmonary bypass was 8 minutes, which is the same as for crystalloid fluid infusions in healthy subjects. The intravascular albumin mass increased. Most patients were hypovolemic prior to the start of anesthesia. Intracellular edema did not occur. .

Dehydration, hemodynamics and fluid volume optimization after induction of general anesthesia

OBJECTIVES: Fluid volume optimization guided by stroke volume measurements reduces complications of colorectal and high-risk surgeries. We studied whether dehydration or a strong hemodynamic response to general anesthesia increases the probability of fluid responsiveness before surgery begins. METHODS: Cardiac output, stroke volume, central venous pressure and arterial pressures were measured in 111 patients before general anesthesia (baseline), after induction and stepwise after three bolus infusions of 3 ml/kg of 6% hydroxyethyl starch 130/0.4 (n = 86) or Ringer's lactate (n = 25). A subgroup of 30 patients who received starch were preloaded with 500 ml of Ringer's lactate. Blood volume changes were estimated from the hemoglobin concentration and dehydration was estimated from evidence of renal water conservation in urine samples. RESULTS: Induction of anesthesia decreased the stroke volume to 62% of baseline (mean); administration of fluids restored this value to 84% (starch) and 68% (Ringer's). The optimized stroke volume index was clustered around 35-40 ml/m2/beat. Additional fluid boluses increased the stroke volume by ≥10% (a sign of fluid responsiveness) in patients with dehydration, as suggested by a low cardiac index and central venous pressure at baseline and by high urinary osmolality, creatinine concentration and ...

Pulse pressure variation and prediction of fluid responsiveness in patients ventilated with low tidal volumes

OBJECTIVE: To determine the utility of pulse pressure variation (ΔRESP PP) in predicting fluid responsiveness in patients ventilated with low tidal volumes (V T) and to investigate whether a lower ΔRESP PP cut-off value should be used when patients are ventilated with low tidal volumes. METHOD: This cross-sectional observational study included 37 critically ill patients with acute circulatory failure who required fluid challenge. The patients were sedated and mechanically ventilated with a V T of 6-7 ml/kg ideal body weight, which was monitored with a pulmonary artery catheter and an arterial line. The mechanical ventilation and hemodynamic parameters, including ΔRESP PP, were measured before and after fluid challenge with 1,000 ml crystalloids or 500 ml colloids. Fluid responsiveness was defined as an increase in the cardiac index of at least 15%. ClinicalTrial.gov: NCT01569308. RESULTS: A total of 17 patients were classified as responders. Analysis of the area under the ROC curve (AUC) showed that the optimal cut-off point for ΔRESP PP to predict fluid responsiveness was 10% (AUC = 0.74). Adjustment of the ΔRESP PP to account for driving pressure did not improve the accuracy (AUC = 0.76). A ΔRESP PP>10% was a better predictor of fluid responsiveness than central venous pressure (AUC = 0.57) or pulmonary wedge pressure (AUC = 051). Of the 37 patients, 25 were in septic shock. The AUC for ΔRESP PP>10% to predict responsiveness in patients with septic shock was 0.484 (sensitivity, 78%; specificity, 93%). CONCLUSION: The parameter D RESP PP has limited value in predicting fluid responsiveness in patients who are ventilated with low tidal volumes, but a ΔRESP PP>10% is a significant improvement over static parameters. A ΔRESP PP > 10% may be particularly useful for identifying responders in patients with septic shock.

Involvement of catecholaminergic medullary pathways in cardiovascular responses to acute changes in circulating volume

Water deprivation and hypernatremia are major challenges for water and sodium homeostasis. Cellular integrity requires maintenance of water and sodium concentration within narrow limits. This regulation is obtained through engagement of multiple mechanisms and neural pathways that regulate the volume and composition of the extracellular fluid. The purpose of this short review is to summarize the literature on central neural mechanisms underlying cardiovascular, hormonal and autonomic responses to circulating volume changes, and some of the findings obtained in the last 12 years by our laboratory. We review data on neural pathways that start with afferents in the carotid body that project to medullary relays in the nucleus tractus solitarii and caudal ventrolateral medulla, which in turn project to the median preoptic nucleus in the forebrain. We also review data suggesting that noradrenergic A1 cells in the caudal ventrolateral medulla represent an essential link in neural pathways controlling extracellular fluid volume and renal sodium excretion. Finally, recent data from our laboratory suggest that these structures may also be involved in the beneficial effects of intravenous infusion of hypertonic saline on recovery from hemorrhagic shock.

Vasodilation increases pulse pressure variation, mimicking hypovolemic status in rabbits

OBJECTIVE: To test the hypothesis that pulse pressure respiratory variation (PPV) amplification, observed in hypovolemia, can also be observed during sodium nitroprusside (SNP)-induced vasodilation. INTRODUCTION: PPV is largely used for early identification of cardiac responsiveness, especially when hypovolemia is suspected. PPV results from respiratory variation in transpulmonary blood flow and reflects the left ventricular preload variations during respiratory cycles. Any factor that decreases left ventricular preload can be associated with PPV amplification, as seen in hypovolemia. METHODS: Ten anesthetized and mechanically ventilated rabbits underwent progressive hypotension by either controlled hemorrhage (Group 1) or intravenous SNP infusion (Group 2). Animals in Group 1 (n = 5) had graded hemorrhage induced at 10 percent steps until 50 percent of the total volume was bled. Mean arterial pressure (MAP) steps were registered and assumed as pressure targets to be reached in Group 2. Group 2 (n = 5) was subjected to a progressive SNP infusion to reach similar pressure targets as those defined in Group 1. Heart rate (HR), systolic pressure variation (SPV) and PPV were measured at each MAP step, and the values were compared between the groups. RESULTS: SPV and PPV were similar between the experimental models in all steps (p > 0.16). SPV increased earlier in Group 2. CONCLUSION: Both pharmacologic vasodilation and graded hemorrhage induced PPV amplification similar to that observed in hypovolemia, reinforcing the idea that amplified arterial pressure variation does not necessarily represent hypovolemic status but rather potential cardiovascular responsiveness to fluid infusion.

GABA in the central amygdaloid nucleus modulates the electrolyte excretion and hormonal responses to blood volume expansion in rats

We investigated the involvement of GABAergic mechanisms of the central amygdaloid nucleus (CeA) in unanesthetized rats subjected to acute isotonic or hypertonic blood volume expansion (BVE). Male Wistar rats bearing cannulas unilaterally implanted in the CeA were treated with vehicle, muscimol (0.2 nmol/0.2 µL) or bicuculline (1.6 nmol/0.2 µL) in the CeA, followed by isotonic or hypertonic BVE (0.15 or 0.3 M NaCl, 2 mL/100 g body weight over 1 min). The vehicle-treated group showed an increase in sodium excretion, urinary volume, plasma oxytocin (OT), and atrial natriuretic peptide (ANP) levels compared to control rats. Muscimol reduced the effects of BVE on sodium excretion (isotonic: 2.4 ± 0.3 vs vehicle: 4.8 ± 0.2 and hypertonic: 4.0 ± 0.7 vs vehicle: 8.7 ± 0.6 µEq·100 g-1·40 min-1); urinary volume after hypertonic BVE (83.8 ± 10 vs vehicle: 255.6 ± 16.5 µL·100 g-1·40 min-1); plasma OT levels (isotonic: 15.3 ± 0.6 vs vehicle: 19.3 ± 1 and hypertonic: 26.5 ± 2.6 vs vehicle: 48 ± 3 pg/mL), and ANP levels (isotonic: 97 ± 12.8 vs vehicle: 258.3 ± 28.1 and hypertonic: 160 ± 14.6 vs vehicle: 318 ± 16.3 pg/mL). Bicuculline reduced the effects of isotonic or hypertonic BVE on urinary volume and ANP levels compared to vehicle-treated rats. However, bicuculline enhanced the effects of hypertonic BVE on plasma OT levels. These data suggest that CeA GABAergic mechanisms are involved in the control of ANP and OT secretion, as well as in sodium and water excretion in response to isotonic or hypertonic blood volume expansion.

Primeiro escore de risco inflamatório das endopróteses de aorta / First inflammatory risk score for aortic endoprostheses

OBJETIVO: Propor um escore de risco inflamatório para tratamento endovascular dos aneurismas da aorta. MÉTODOS: Vinte e cinco pacientes foram seguidos do período pré-operatório até 3º mês de pós-operatório (1 hora, 6 horas, 24 horas, 48 horas, 7 dias, 1 mês, 2 meses e 3 meses). Variáveis inflamatórias avaliadas foram proteína C reativa, velocidade de hemossedimentação, interleucinas (IL-6, IL8), fator de necrose tumoral alfa, L-selectina, molécula de adesão intercelular (ICAM-1), transfusão de hemáceas, volume de cristalóide, volume de contraste, material da prótese, número de próteses, contagem total de leucócitos e linfócitos. O teste de Spearman apontou as variáveis candidatas ao maior risco inflamatório, segundo P < 20 por cento. A regressão logística apontou variáveis selecionáveis para escore final segundo P < 10 por cento. A análise da curva ROC revelou valores de corte para variáveis selecionadas pela regressão logística. RESULTADOS: Variáveis apresentadas pelo teste de Spearman foram: volume de cristalóide (P = 0,04), material da prótese (P = 0,04), volume de contraste (P=0,02), IL-8 préoperatória (P= 0,10), ICAM-1 1 mês (P=0,03) e L-selectina 1 mês (P = 0,06). A regressão logística revelou que os valores do volume de cristalóide e IL-8 pré-operatória são primordiais para constituição do escore de risco inflamatório para tratamento endovascular dos aneurismas da aorta. O escore de risco seria dividido em três categorias (leve, moderado e grave), com base em intervalos numéricos das duas variáveis selecionadas e as categorias seriam correlacionadas com achados clínicos CONCLUSÃ: Volume de cristalóide e IL-8 pré-operatória são variáveis que poderiam contribuir para categorizar risco inflamatório e, desse modo, ter um papel prognóstico no tratamento endovascular dos aneurismas da aorta.

OBJECTIVE: To purpose an inflammatory risk score for aortic aneurysm endovascular treatment. METHODS: Twenty-five patients were followed-up from preoperative period to third month postoperatively (1-hour, 6-hour, 24-hour, 48-hour, 7-day, 1-month, 2- month and 3month). Inflammatory variables were C-reactive protein, hemosedimentation velocity, interleukins (IL-6, IL-8), tumor necrosis factor-Alpha, L-selectin, intercellular adhesion molecule (ICAM-1), red blood cells transfusion, volume of crystalloid, volume of contrast, type of endoprosthesis, number of endoprostheses, total count of leukocytes and lymphocytes. Spearman test defined the variables considered as candidates to higher inflammatory risk based on P < 20 percent. Logistic regression defined the variables considered as selected for final score based on P < 10 percent. ROC curve analysis revealed the cut-off values for variables selected by logistic regression. RESULTS: Variables defined by Spearman test were: volume of crystalloid (P=0.04), type of endoprosthesis (P=0.04), volume of contrast (P=0.02), preoperative IL-8 (P = 0.10), 1 - month ICAM-1 (P=0.03) and 1-month L-selectin (P=0.06). Logistic regression revealed that volume of crystalloid and preoperative IL-8 values are relevant for composition of inflammatory risk score for aortic aneurysm endovascular treatment. Risk score would be divided into three categories (mild, moderate and severe) based on numeric intervals of these two variables and the categories would be correlated to clinical findings. CONCLUSION: Volume of crystalloid and preoperative IL-8 are variables that might contribute to categorize inflammatory risk and thereby might play a prognostic role for aortic aneurysm endovascular treatment.

Alta utilidad de monitorización hemodinámica con ecocardiografía transesofágica intraoperatoria en cirugía ortopédica / Intraoperative hemodynamic monitoring using transesophageal echocardiography in orthopedic surgery

Background: Orthopedic surgery is commonly performed in elderly patients with higher cardiovascular surgical risk. Hemodynamic monitoring in these patients may prevent perioperative complications. Aim: To assess the usefulness of transesophageal echocargiography (TEE) for intraoperative cardiovascular monitoring during orthopedic surgery. Material and methods: Patients older than 65 years subjected to orthopedic surgery using general anesthesia and with a high cardiovascular risk were studied. Intraoperative TEE was performed to assess intravascular volume, myocardial contractility and the presence of myocardial ischemia. Results: Fifty three patients aged 72±5 years were studied. Hemodynamic stability was detected in 68 percent of patients, mainly reflected as episodes of hypovolemia. Myocardial ischemia was detected in two patients and embolic episodes in six (11 percent). Conclusions: Intraoperative TEE was useful for the hemodynamic evaluation of patients with high cardiovascular risk.

Regional differences in veins wall viscosity, compliance. energetics and damping: analysis of the pressure-diameter relationship during cyclical overloads

Background: The characterization of the dynamic process of veins walls is essential to understand venous functioning under normal and pathological conditions. However, little work has been done on dynamic venous properties. Aim: To characterize vein compliance (C), viscosity (η), peak-strain (W St) and dissipated (W D) energy, damping (ξ), and their regional differences in order to evalúate their role in venous functioning during volume-pressure overloads. Methods: In a mock circulation, pressure (P) and diameter (D) of different veins (anterior cava, jugular and femoral; from 7 sheep), were registered during cyclical volume-pressure pulses. From the P-D relationship, C, W St and ξ (at low and high P-D leveis), η and W D were calculated. Resulls: For each vein there were P-dependent differences in biomechanical, energetics, and damping capability. There were regional-differences in C, η), W St and W D (p<0.05), but not in ξ. Conclusión: The regional-dependent differences in dynamics and energetics, and regional-similitude in damping could be important to ensure venous functioning during acute overloads. The lower C and higher W St and W D found in back-limb veins (femoral), commonly submitted to high volume-pressure loads (i.e. during walking), could be considered relevant to ensure adequate venous system functionality and venous wall protection simultaneously.

Responsiveness to different volume therapies following hemodilution and hemorrhagic shock: a comparative experimental study in rats

Guidelines for volume replacement for acutely hemorrhaged and hemodiluted trauma patients have not been well established. Purpose: To evaluate the effects of acute hemodilution on mean arterial pressure (MAP), and responsiveness of acutely hemodiluted and subsequently hemorrhaged rats to different volume therapies. Methods: 180 rats were hemodiluted to simulate hemorrhaged trauma patients with persistent bleeding after high volume replacement with isotonic solutions. Thirty hemodiluted [Anemia (ANE) group] animals received no further treatment. The remaining 150 animals were subjected to hypovolemic shock and randomized into five groups, according to the treatment option employed: Control (CTL) animals did not receive subsequent treatment after hemorrhagic hypovolemia, SAL4 animals received isotonic saline 4 mL/kg, SAL32 animals received isotonic saline 32 mL/kg, HS animals received hypertonic saline 4 mL/kg and BLD animals received re-infusion of drawn blood. Results: Highest mean arterial pressure (MAP) was achieved by BLD, followed by SAL32 and HS. MAP after treatment of BLD, HS, SAL32 and ANE were higher than CTL (p=0.036). At 85 and 95 minutes of experiment, SAL4, SAL32 and HS presented the lowest hematocrit levels (p<0.01). At day 3, ANE, CTL and HS had the highest hematocrit. SAL4 and CTL groups presented the highest mortality rates. Conclusion: Hypertonic saline is an effective and safe initial therapy for hemodiluted rats undergoing hemorrhagic shock, with an overall outcome comparable to blood replacement or high volume isotonic saline administration.

A conduta para reposição volêmica em pacientes traumatizados, hemodiluídos não está bem estabelecida. Objetivo: Avaliar o efeito da hemodiluição sobre a pressão arterial média (PAM), bem como a resposta de ratos agudamente hemodiluídos e submetidos a choque hemorrágico, à reanimação com diferentes soluções. Métodos: 180 ratos foram hemodiluídos, simulando pacientes traumatizados com sangramento persistente após reposição com soluções isotônicas. Trinta ratos hemodiluídos (grupo ANE) foram observados, sem tratamento. Os demais 150 foram submetidos a choque hipovolêmico e randomizados em 5 grupos segundo a opção terapêutica: CTL (controle), sem tratamento subseqüente após hipovolemia hemorrágica; SAL4 que recebeu 4 mL/kg de salina isotônica; SAL32 que recebeu 32 mL/kg de salina isotônica ; SH que recebeu 4mL/kg de salina hipertônica; e BLD que recebeu reinfusão do sangue removido. Resultados: A pressão arterial média (PAM) mais alta ocorreu no grupo BLD, seguida pelo SAL32, e SH. A PAM após tratamento nos grupos BLD, SH, SAL32 e ANE foram maiores que no CTL (-=0.036). Aos 85 e 95 minutos do experimento, SAL4, SAL32, e SH apresentaram os menores hematócritos (p<0.01). No 3° dia, ANE, CTL e SH apresentaram os maiores hematócritos. SAL4 e CTL apresentaram as maiores taxas de mortalidade. Em conclusão, nossos resultados indicam que a SH é uma terapia inicial efetiva e segura em ratos hemodiluídos, submetidos a hemorrágico choque, com prognóstico comparável à reposição com sangue ou administração de grande volume de solução isotônica.

Low hematocrit impairs gastric mucosal CO2 removal during experimental severe normovolemic hemodilution

OBJECTIVE: The net effects of acute normovolemic hemodilution with different hemoglobin levels on splanchnic perfusion have not been elucidated. The hypothesis that during moderate and severe normovolemic hemodilution, systemic and splanchnic hemodynamic parameters, oxygen-derived variables, and biochemical markers of anaerobic metabolism do not reflect the adequacy of gastric mucosa, was tested in this study. METHODS: Twenty one anesthetized mongrel dogs (16 ± 1 kg) were randomized to controls (CT, n = 7, no hemodilution), moderate hemodilution (hematocrit 2 5 percent ± 3 percent, n = 7) or severe hemodilution (severe hemodilution, hematocrit 15 percent ± 3 percent, n = 7), through an isovolemic exchange of whole blood and 6 percent hydroxyethyl starch, at a 20 mL/min rate, to the target hematocrit. The animals were followed for 120 min after hemodilution. Cardiac output (CO, L/min), portal vein blood flow (PVF, mL/min), portal vein-arterial and gastric mucosa-arterial CO2 gradients (PV-artCO2 and PCO2 gap, mm Hg, respectively) were measured throughout the experiment. RESULTS: Exchange blood volumes were 33.9 ± 3.3 and 61.5 ± 5.8 mL/kg for moderate hemodilution and severe hemodilution, respectively. Arterial pressure and systemic and regional lactate levels remained stable in all groups. There were initial increases in cardiac output and portal vein blood flow in both moderate hemodilution and severe hemodilution; systemic and regional oxygen consumption remained stable largely due to increases in oxygen extraction rate. There was a significant increase in the PCO2-gap value only in severe hemodilution animals. CONCLUSION: Global and regional hemodynamic stability were maintained after moderate and severe hemodilution. However, a very low hematocrit induced gastric mucosal acidosis, suggesting that gastric mucosal CO2 monitoring may be useful during major surgery or following trauma.

OBJETIVO: Os efeitos da hemodiluição normovolêmica com diferentes níveis de hemoglobina na perfusão esplâncnica são pouco conhecidos. Testamos a hipótese que durante a hemodiluição moderada e acentuada, os parâmetros hemodinâmicos sistêmicos e regionais e as variáveis relacionadas ao metabolismo de oxigênio não refletem a adequação da perfusão da mucosa gástrica. MÉTODOS: Vinte e um cães anestesiados com fentanil e vecurônio (16±1 kg) foram randomizados como controles (CT, n=7, sem hemodiluição normovolêmica), hemodiluição normovolêmica moderada (Ht 25±3 por cento, n=7) ou hemodiluição normovolêmica acentuada (Ht 15±3 por cento, n=7), pela troca isovolêmica entre o sangue total e hidroxietil amido a 6 por cento, 20 mL/min até o hematócrito pré-estabelecido para cada grupo. Os animais foram acompanhados por 120 min após a hemodiluição normovolêmica. Durante todo o experimento foram medidos o débito cardíaco (CO, L/min), o fluxo de veia porta (PVF, mL/min), e os gradientes de CO2 veia porta-arterial e mucosa gástrica-arterial (PV-artCO2 and PCO2-gap, mmHg, respectivamente). RESULTADOS: O volume de sangue trocado foi de 33,9±3,3 mL/kg para hemodiluição normovolêmica moderada e de 61,5±5,8 mL/kg para a hemodiluição normovolêmica acentuada. A pressão arterial e os níveis de lactato sistêmico e regional permaneceram estáveis em todos os grupos. Houve aumentos iniciais de débito cardíaco e de fluxo de veia porta, tanto na hemodiluição normovolêmica moderada quanto na hemodiluição normovolêmica acentuada; o consumo de oxigênio sistêmico e regional permaneceram estáveis, principalmente por conta de aumentos na taxa de extração de oxigênio. O PCO2-gap apresentou aumento significativo apenas nos animais submetidos a hemodiluição normovolêmica acentuada. CONCLUSÃO: Ocorre estabilidade hemodinâmica global e regional tanto na hemodiluição normovolêmica moderada quanto na acentuada. Entretanto, o hematócrito de 15 por cento induziu acidose moderada de mucosa gástrica, o que pode ser relevante em procedimentos cirúrgicos de grande porte ou no trauma.