Evaluation of pulse pressure variation (PPV) using different concentrations of isoflurane, desflurane and sevoflurane: experimental model in pigs

Introdução: Os anestésicos inalatórios empregados atualmente na prática clinica (isoflurano, sevoflurano e desflurano) possuem propriedades farmacocinéticas que favorecem rápida recuperação da anestesia, porém seu uso pode causar instabilidade hemodinâmica dose-dependente, relacionado à depressão direta da contratilidade miocárdica ou à hipovolemia relativa, derivado de um sequestro de sangue devido à vasodilatação do leito vascular periférico. Este estudo visa avaliar o comportamento da VPP durante a anestesia inalatória. Para tanto se utilizou três diferentes agentes inalatórios (isoflurano, sevoflurano e desflurano) em diferentes concentrações inaladas. Métodos: Foram utilizados 25 suínos divididos aleatoriamente em três grupos. Os animais foram submetidos à anestesia com o anestésico do respectivo grupo. Imediatamente após a determinação da CAM individual do agente inalatório em cada animal, ocorreu a primeira coleta de dados. O animal foi, então, exposto a diferentes níveis de CAM (1,0 CAM; 1,25 CAM) seguido por uma exposição decrescente de CAM (1,0 CAM); provocou-se então uma hemorragia correspondente a 30% da volemia e exposição a dois níveis de CAM (1,0 e 1,25), com 20 minutos em cada exposição. Ao final de cada período os valores ecocardiográficos e do VPP foram mensurados. A análise estatística foi realizada através de provas paramétricas empregando-se o método de comparações múltiplas para análise de variância com medidas repetidas (ANOVA). O grau de significância foi de 5% (p < 0,05). Resultados: Há aumento na variação de pressão de pulso com incremento de 25% na CAM dos anestésicos inalatórios (de 8±1 para 11±3% no grupo DESF, de 7±2 para 9±2 no grupo SEVO e de 9±4 para 10±3% no grupo ISO) sem diferença estatística entre os anestésicos. Apesar deste aumento na CAM e significativa hipotensão e queda no débito cardíaco, o aumento na VPP não torna o paciente responsivo a infusão de fluidos (o VPP permaneceu abaixo de 13%). Há pequena queda na PAM quando se eleva a CAM dos anestésicos em 25%, porém só há queda estatisticamente significativa no grupo DESF (de 84±7 para 68±12 mmHg). Não foram observadas alterações importantes em relação à contratilidade miocárdica. Conclusão: Observou-se que a VPP não é influenciada como o uso dos diferentes anestésicos inalatórios e apesar dos efeitos cardiovasculares esperados destes agentes, mantem-se a capacidade de demonstrar alterações de pré-carga mesmo em concentrações correspondentes a 1,25 CAMBackground: Inhalant anesthetics, such as isoflurane, sevoflurane and desflurane are widely used in daily clinical practice due to its pharmacological properties allowing a rapid recovery from anesthesia. Nevertheless, its use can lead to dose-dependent hemodynamic instability related to direct depression in myocardial contractility or to a relative hypovolemia caused by vasodilation of peripheral capillary bed. This study aims to evaluate the behavior of PPV during inhalant anesthesia. For this, three different anesthetics were used (isoflurane, sevoflurane and desflurane) with different inhaled concentrations. Methods: 25 young pigs were randomly assigned into three groups. Animals were anesthetized with its correspondent agent according to its group. After individual determination of minimal alveolar concentration (MAC), first data collection occurred. Pigs were then exposed to different MAC (1MAC and 1,25 MAC) followed by a decrease in MAC (1 MAC). At this point a 30% of estimated volemia hemorrhage was caused and pigs were exposed to a period of 1 MAC and after that 1,25 MAC. Each period lasted 20 minutes. At the end of each period, hemodynamic parameters and echocardiography were collected. Data were submitted to analysis of variance for repeated measures (ANOVA). P<0,05 was considered statistically significant. Results: There was an increase in PPV when with 1,25 MAC of all anesthetics. (from 8±1 to 11±3% in group DESF, from 7±2 to 9±2 in group SEVO and from 9±4 to 10±3% in group ISO), but without statistical difference among groups. Although there was an increase in PPV, followed by hypotension and drop in cardiac index, patients werent fluid responsive with a 25% increase in MAC, since PPV was lower than 13%. The decrease in blood pressure followed by 1,25MAC was only significant in DESF group (from 84±7 to 68±12 mmHg). No important alterations related to myocardial contractility were observed. Conclusion: PPV is not influenced by the use of different inhalant anesthetics and although there are cardiovascular effects of these agents which are expected, and were able to demonstrate alterations in preload even in concentration of 1,25 MA

Pulse pressure variation and stroke volume variation under different inhaled concentrations of isoflurane, sevoflurane and desflurane in pigs undergoing hemorrhage.

OBJECTIVES: Inhalant anesthesia induces dose-dependent cardiovascular depression, but whether fluid responsiveness is differentially influenced by the inhalant agent and plasma volemia remains unknown. The aim of this study was to compare the effects of isoflurane, sevoflurane and desflurane on pulse pressure variation and stroke volume variation in pigs undergoing hemorrhage. METHODS: Twenty-five pigs were randomly anesthetized with isoflurane, sevoflurane or desflurane. Hemodynamic and echocardiographic data were registered sequentially at minimum alveolar concentrations of 1.00 (M1), 1.25 (M2), and 1.00 (M3). Then, following withdrawal of 30% of the estimated blood volume, these data were registered at a minimum alveolar concentrations of 1.00 (M4) and 1.25 (M5). RESULTS: The minimum alveolar concentration increase from 1.00 to 1.25 (M2) decreased the cardiac index and increased the central venous pressure, but only modest changes in mean arterial pressure, pulse pressure variation and stroke volume variation were observed in all groups from M1 to M2. A significant decrease in mean arterial pressure was only observed with desflurane. Following blood loss (M4), pulse pressure variation, stroke volume variation and central venous pressure increased (p < 0.001) and mean arterial pressure decreased in all groups. Under hypovolemia, the cardiac index decreased with the increase of anesthesia depth in a similar manner in all groups. CONCLUSION: The effects of desflurane, sevoflurane and isoflurane on pulse pressure variation and stroke volume variation were not different during normovolemia or hypovolemia

Outcomes in Newly Diagnosed Atrial Fibrillation and History of Acute Coronary Syndromes: Insights from GARFIELD-AF

BACKGROUND: Many patients with atrial fibrillation have concomitant coronary artery disease with or without acute coronary syndromes and are in need of additional antithrombotic therapy. There are few data on the long-term clinical outcome of atrial fibrillation patients with a history of acute coronary syndrome. This is a 2-year study of atrial fibrillation patients with or without a history of acute coronary syndromes