Comparison of Two Central Venous Pressure Control Strategies to Prevent Atrial Fibrillation After Coronary Artery Bypass Grafting / Comparação de Duas Estratégias de Controle de Pressão Venosa Central na Prevenção de Fibrilação Atrial em Pós-Operatório de Revascularização do Miocárdio

Abstract Background: Atrial fibrillation (AF) takes place in 10-40% of patients undergoing coronary artery bypass grafting (CABG), and increases cardiovascular mortality. Enlargement of atrial chambers is associated with increased AF incidence, so patients with higher central venous pressure (CVP) are expected to have larger atrial distension, which increases AF incidence. Objective: To compare post-CABG AF incidence, following two CVP control strategies. Methods: Interventional, randomized, controlled clinical study. The sample comprised 140 patients undergoing CABG between 2011 and 2015. They were randomized into two groups, G15 and G20, with CVP maintained ≤ 15 cmH2O and ≤ 20 cmH2O, respectively. Results: 70 patients were included in each group. The AF incidence in G15 was 8.57%, and in G20, 22.86%, with absolute risk reduction of 14.28%, and number needed to treat (NNT) of 7 (p = 0.03). Mortality (G15 = 5.71%; G20 = 11.42%; p = 0.07), hospital length of stay (G15 = 7.14 days; G20 = 8.21 days; p = 0.36), number of grafts (median: G15 = 3, G2 = 2; p = 0.22) and cardiopulmonary bypass use (G15 = 67.10%; G20 = 55.70%; p = 0.22) were statistically similar. Age (p = 0.04) and hospital length of stay (p = 0.001) were significantly higher in patients who developed AF in both groups. Conclusion: Keeping CVP low in the first 72 post-CABG hours reduces the relative risk of AF, and may be useful to prevent AF after CABG.

Resumo Fundamento: A fibrilação atrial (FA) ocorre em 10-40% dos pacientes submetidos a cirurgia de revascularização miocárdica (RM), e eleva a mortalidade cardiovascular. Como o aumento dos átrios está associado ao aumento da incidência de FA, espera-se que pacientes com pressão venosa central (PVC) mais alta tenham maior distensão atrial, o que eleva a incidência dessa arritmia. Objetivo: Comparar a incidência de FA em pós-operatório de RM, seguindo duas estratégias de controle de PVC. Métodos: Estudo clínico randomizado controlado intervencionista. A amostra foi composta por 140 pacientes submetidos a RM entre 2011 e 2015. Os pacientes foram randomizados em dois grupos, G15 e G20, mantidos com PVC máxima de 15 cmH2O e 20 cmH2O, respectivamente. Resultados: Foram incluídos 70 pacientes em cada grupo. A incidência da arritmia em G15 foi de 8,57% e, no G20, de 22,86%, com redução de risco absoluto de 14,28% e número necessário para tratar (NNT) de 7 (p = 0,03). Mortalidade (G15 = 5,71%; G20 = 11,42%; p = 0,07), tempo de internamento (G15 = 7,14 dias; G20 = 8,21 dias; p = 0,36), número de enxertos (medianas: G15 = 3, G2 = 2; p = 0,22) e uso de circulação extracorpórea (G15 = 67,10%; G20 = 55,70%; p = 0,22) mostraram-se estatisticamente semelhantes. A idade (p = 0,04) e o tempo de internamento (p = 0,001) foram significativamente maiores nos pacientes que desenvolveram FA nos dois grupos. Conclusão: Manter a PVC com valores mais baixos nas primeiras 72h após a cirurgia de RM reduz o risco relativo de FA e pode ser uma ferramenta útil na prevenção da FA após RM.

Methylene blue to treat protamine-induced anaphylaxis reactions. An experimental study in pigs

ABSTRACT Objective: To examine if methylene blue (MB) can counteract or prevent protamine (P) cardiovascular effects. Methods: The protocol included five heparinized pig groups: Group Sham -without any drug; Group MB - MB 3 mg/kg infusion; Group P - protamine; Group P/MB - MB after protamine; Group MB/P - MB before protamine. Nitric oxide levels were obtained by the nitric oxide/ozone chemiluminescence method, performed using the Nitric Oxide Analizer 280i (Sievers, Boulder, CO, USA). Malondialdehyde plasma levels were estimated using the thiobarbiturate technique. Results: 1) Groups Sham and MB presented unchanged parameters; 2) Group P - a) Intravenous protamine infusion caused mean arterial pressure decrease and recovery trend after 25-30 minutes, b) Cardiac output decreased and remained stable until the end of protamine injection, and c) Sustained systemic vascular resistance increased until the end of protamine injection; 3) Methylene blue infusion after protamine (Group P/MB) - a) Marked mean arterial pressure decreased after protamine, but recovery after methylene blue injection, b) Cardiac output decreased after protamine infusion, recovering after methylene blue infusion, and c) Sustained systemic vascular resistance increased after protamine infusion and methylene blue injections; 4) Methylene blue infusion before protamine (Group MB/P) - a) Mean arterial pressure decrease was less severe with rapid recovery, b) After methylene blue, there was a progressive cardiac output increase up to protamine injection, when cardiac output decreased, and c) Sustained systemic vascular resistance decreased after protamine, followed by immediate Sustained systemic vascular resistance increase; 5) Plasma nitrite/nitrate and malondialdehyde values did not differ among the experimental groups. Conclusion: Reviewing these experimental results and our clinical experience, we suggest methylene blue safely prevents and treats hemodynamic protamine complications, from the endothelium function point of view.

Treatment of ethanol-induced acute pulmonary hypertension and right ventricular dysfunction in pigs, by sildenafil analogue (UK343-664) or nitroglycerin.

In patients at risk for sudden ethanol (ETOH) intravascular absorption, prompt treatment of pulmonary hypertension (PHTN) will minimise the risk of cardiovascular decompensation. We investigated the haemodynamic effects of intravenous ETOH and the pulmonary vasodilatory effects of a sildenafil analogue (UK343-664) and nitroglycerin (NTG) during ETOH-induced PHTN in pigs. We studied pulmonary and systemic haemodynamics, and right ventricular rate or time derivate of pressure rise during ventricular contraction ( =dP/dT), as an index of contractility, in 23 pigs. ETOH was infused at a rate of 50 mg/kg/min, titrated to achieve a twofold increase in mean pulmonary arterial pressure (MPAP), and then discontinued. The animals were randomised to receive an infusion of 2 ml/kg ( n = 7) normal saline, a 500-microg/kg bolus of UK343-664 ( n = 8), or NTG 1 microg/kg ( n = 8); each was given over 60 seconds. Following ETOH infusion, dP/dT decreased central venous pressure (CVP), and MPAP increased significantly, resulting in significantly increased pulmonary vascular resistance (PVR). Within 2 minutes after treatment with either drug, CVP, heart rate (HR), and the systemic vascular resistance-to-pulmonary vascular resistance (SVR/PVR) ratio returned to baseline. However, at that time, only in the UK343-664 group, MPAP and dP/dT partially recovered and were different from the respective values at PHTN stage. NTG and UK343-664 decreased PVR within 2 minutes, from 1241+/-579 and 1224+/-494 dyne . cm/sec 5 , which were threefold-to-fourfold increased baseline values, to 672+/-308 and 538+/-203 dyne . cm/sec 5 respectively. However, only in the UK343-664 group, changes from baseline PVR values after treatment were significant compared to the maximal change during target PHTN. Neither drug caused a significant change in SVR. In this model of ETOH-induced PHTN, both UK343-664 and NTG were effective pulmonary vasodilators with a high degree of selectivity. However, the changes from baseline values of PVR, and the partial recovery of systemic pressure and RV contractility compared to the maximal change during target PHTN, were significant only in the sildenafil analogue group.

Hemodynamic effects of local anesthetics intoxication: experimental study in swine with levobupivacaine and bupivacaine

PURPOSE: To compare the hemodynamic repercussions following a toxic dose of levobupivacaine and bupivacaine intravascularly injected in swines. Methods: Large White pigs were anesthetized with thiopental, tracheal intubation was performed and mechanical ventilation was instituted. Hemodynamic variables were recorded with invasive pressure monitoring and pulmonary artery catheterization (Swan-Ganz catheter). After a 30-minute resting period, the animals were randomly divided into two groups in a double-blinded fashion and received a bolus injection of 4 mg/kg of either agent for intoxication. Hemodynamic results were then evaluated at 1, 5, 10, 15, 20 and 30 minutes. RESULTS: Levobupivacaine had greater hemodynamic repercussions than racemic bupivacaine. These results disagree with those found when the levorotatory isomer of bupivacaine was used in humans, but are in agreement with recently reported findings in animals. CONCLUSION: Levobupivacaine was shown to be more toxic in pigs than racemic bupivacaine when large doses are injected intravenously.

OBJETIVO: Comparar as repercussões hemodinâmicas da levobupivacaína e bupivacaína após uma dose tóxica intravascular em suínos. MÉTODOS: Porcos Large-White foram anestesiados com tiopental, entubados e mantidos em ventilação controlada mecânica. Parâmetros hemodinâmicos foram registrados através de pressão invasiva e cateterização da artéria pulmonar (cateter de Swan-Ganz). Após 30 minutos de repouso, os animais foram divididos aleatoriamente em dois grupos e receberam injeção endovenosa em duplo-cego de 4 mg/kg de um ou outro agente anestésico simulando uma intoxicação. Foram avaliados resultados hemodinâmicos aos 1, 5, 10, 15, 20 e 30 minutos. RESULTADOS: Levobupivacaína teve maiores repercussões hemodinâmicas que a bupivacaína racêmica. Estes resultados discordam daqueles encontrados com o isômero levógiro em humanos, mas estão de acordo com resultados recentemente informados em animais. CONCLUSÃO: Levobupivacaína mostrou ser agente mais tóxico em suínos do que a bupivacaína racêmica quando grandes doses são injetadas por via intravascular.

1.8 cineole decreases gastric compliance in anesthetized rats

PURPOSE: To study the effect of 1,8 cineoleee components of the essencial oil of Croton nepetaefolius - plant of North-East of Brasil, used in the popular medicine for riots of the gastrointestinal tract - on the motor behavior of the gut of Wistar rats. METHODS: Used 16 male animals under jejun of 24h weighing 300-350g. The effect of 1.8 cineoleee (1 or 3mg/Kg) on gastric compliance had been lead in anaesthetized rats. The variations of the gastric volume (GV), had been measured by plethysmography, while AP, HR and CVP had been monitored continuously by a digital system of data acquisition. RESULTS: Observe reduction of the GV, which was significant on 30, 40, 50 and 60min after treatment (2.0±0.1; 1.9±0.1; 1.8±0.1 and 1.7±0.1mL, versus 2.1±0.2mL). The AP presented significant fall after the administration of 1.8 cineoleee, remaining thus during 60min of monitorization (87.9±7.7; 87.6±7.1; 87.9±6.4; 87.8±5.7; 86.0±5.5 and 87.7±6.0mmHg, respectively versus 94.4±6.2 mmHg), as well as the HR (366.3±13.4; 361.7±11.5; 357.3±10.4; 353.0±10.4; 348.3±11.1 and 350.4±13.7bpm, respectively versus 395.2±11.1bpm). The CVP did not suffer significant variations after treatment. CONCLUSION: Observe the 1.8 cineoleee reduces the gastric compliance in anaesthetized rats besides presenting effect hipotensor and bradicardic; probably for direct action on the gastrointestinal and vascular smooth muscel and moduling the autonomic nervous system.

OBJETIVO: Estudar o efeito do 1.8 cineol, componente do Cróton nepetaefolius (planta do Nordeste) comumente usada na medicina popular para distúrbios do trato gastrintestinal (TGI), sobre o comportamento motor do TGI de ratos Wistar anestesiados. MÉTODOS: Utilizamos 16 animais machos, pesando entre 300 a 350g. Os estudos de complacência gástrica foram conduzidos em animais sob jejum de 24h. As variações do volume gástrico (VG), foram medidas por pletismografia, enquanto a PA, FC e PVC foram monitoradas continuamente por um sistema digital de aquisição de dados. RESULTADOS: Observamos diminuição do VG, o qual foi significativo aos 30, 40, 50 e 60min após o tratamento com 1.8 cineol quando comparado ao perído basal (2,0±0,1; 1,9±0,1; 1,8±0,1 e 1,7±0,1mL, vs 2,1±0,2mL). A PA apresentou queda significativa após a administração de 1.8 cineol, mantendo-se assim durante os 60min de monitoração (87,9±7,7; 87,6±7,1; 87,9±6,4; 87,8±5,7; 86,0±5,5 e 87,7±6,0mmHg, respectivamente vs 94,4±6,2; mmHg), bem como a FC (366,3±13,4; 361,7±11,5; 357,3±10,4; 353,0±10,4; 348,3±11,1 e 350,4±13,7bpm respectivamente vs 395,2±11,1bpm). Já a PVC não sofreu variações significativas durante após o tratamento. CONCLUSÃO: O 1.8 cineol diminui a complacência gástrica em ratos anestesiados além de apresentar efeitos hipotensor e bradicárdico; provavelmente por ação direta sobre a musculatura lisa gastrintestinal e vascular e modulação do sistema nervoso autônomo.