Atelectasias durante anestesia: fisiopatología y tratamiento

JUSTIFICATIVA E OBJETIVOS: O colapso pulmonar intra-operatório é uma complicação de elevada incidência em pacientes submetidos à intervenção cirúrgica sob anestesia geral com relaxamento/paralisia da musculatura. Essa complicação está associada à piora das trocas gasosas no intra-operatório e, em alguns casos, necessidade de suporte respiratório prolongado no período pós-operatório. Os objetivos deste estudo foram revisar os aspectos fisiopatológicos da formação de atelectasias durante anestesia geral e as possíveis manobras terapêuticas para prevenir e tratar essa complicação. CONTEÚDO: Nesta revisão, os conceitos sobre a incidência de atelectasias intra-operatórias, os fatores relacionados com o seu desenvolvimento, tanto mecânicos quanto associados ao ajuste do respirador durante procedimento cirúrgico, os aspectos do diagnóstico e as estratégias de prevenção e tratamento foram abordados de maneira sistemática. CONCLUSÕES: A compreensão dos mecanismos relacionados com o desenvolvimento do colapso pulmonar durante o período intra-operatório, assim como o seu tratamento, pode contribuir para a redução da incidência de complicações pulmonares pós-operatórias, o tempo de recuperação e os custos hospitalares.BACKGROUND AND METHODS: The incidence of intraoperative pulmonary collapse is elevated in patients undergoing surgery under general anesthesia with muscle relaxation/paralysis. This complication is associated with worsening intraoperative gas exchange and, in some cases, the need for prolonged postoperative respiratory support. The objective of this report was to review the pathophysiological aspects of atelectasis during general anesthesia and possible therapeutic maneuvers that could prevent and treat this complication. CONTENTS: This review discusses the concepts about the incidence of intraoperative atelectasis, factors that influence their development, both mechanical and those related to mechanical ventilator settings during the surgery, diagnostic criteria, and strategies to prevent and treat this complication. CONCLUSIONS: Understanding of the mechanisms related with the development of intraoperative pulmonary collapse, as well as its treatment, can contribute to reduce the incidence of postoperative pulmonary complications, the length of recovery and hospital costs.JUSTIFICATIVA Y OBJETIVOS: El colapso pulmonar intraoperatorio es una complicación de elevada incidencia en pacientes sometidos a la intervención quirúrgica bajo anestesia general con relajamiento/parálisis de la musculatura. Esta complicación está asociada al empeoramiento de los cambios de gas en el intraoperatorio y en algunos casos, necesidad de soporte respiratorio prolongado en el período postoperatorio. Los objetivos de este estudio fueron los de revisar los aspectos fisiopatológicos de la formación de atelectasias durante anestesia general y las posibles maniobras terapéuticas para prevenir y tratar esa complicación. CONTENIDO: En esta revisión, los conceptos sobre la incidencia de atelectasias intraoperatorias, los factores relacionados a su desarrollo, tanto mecánicos como los relacionados al ajuste del respirador durante el procedimiento quirúrgico, los aspectos del diagnóstico y las estrategias de prevención y tratamiento fueron abordados de manera sistemática. CONCLUSIONES: La comprensión de los mecanismos relacionados al desarrollo del colapso pulmonar durante el período intraoperatorio, como también su tratamiento, pueden contribuir para la reducción de la incidencia de complicaciones pulmonares postoperatorias, el tiempo de recuperación y los costes de las internaciones en los hospitales

Resucitación Hemostática en el Choque Hemorrágico Traumático: Relato de Caso

ResumenJustificativa y objetivos: El objetivo de este artículo es relatar un caso en que la estrategia damage control (control de daños [RDC]) con resucitación hemostática, fue usada con éxito en paciente politraumatizada con choque hemorrágico grave.Relato de caso: Paciente de 32 años, con choque hemorrágico grave por politraumatismo con fractura de cadera, que evolucionó con acidosis, coagulopatía e hipotermia. Durante la resucitación volémica, la paciente recibió transfusión de hemocomponentes a una razón de PFC/CP/CH de 1:1:1. Evolucionó en el período intraoperatorio, con una mejoría de los parámetros perfusionales y no necesitó fármacos vasoactivos. Al término de la operación, la paciente fue derivada a la unidad de cuidados intensivos y tuvo su alta al séptimo día del postoperatorio.Conclusiones: La terapéutica ideal del choque hemorrágico traumático todavía no ha quedado establecida, pero la rapidez en el control de la hemorragia y del rescate perfusional, junto con protocolos terapéuticos bien definidos, sientan las bases para evitar la progresión de la coagulopatía y la refractariedad del choque

Obesity influences propranolol pharmacokinetics in patients undergoing coronary artery bypass grafting employing cardiopulmonary bypass

As concentrações plasmáticas e a disposição cinética do propranolol podem ser alteradas pela circulação extracorpórea (CEC). Investigou-se a influência da obesidade na farmacocinética do propranolol em pacientes submetidos à revascularização do miocárdio empregando a CEC. Investigaram-se quinze pacientes, recebendo cronicamente propranolol no pré- (10-40 mg, 2 a 3 vezes ao dia PO) e no pós-operatório (10 mg, 1 vez ao dia) sendo os mesmos distribuídos em dois grupos: obesos (n = 9, média 29,4) kg/m²; e não-obesos (n = 6, média 24,8 kg/m²). Colheram-se amostras seriadas de sangue nos períodos pré- e pós-operatório (Ä); determinaram-se as concentrações plasmáticas do propranolol através da cromatografia líquida de alta eficiência. Aplicou-se o software PK Solutions 2.0 para estimativa dos parâmetros cinéticos. Não se registrou alteração na farmacocinética do propranolol avaliada através dos parâmetros meia-vida biológica (t1/2), volume de distribuição aparente (Vd/F) e depuração plasmática (CL T/F) no grupo de pacientes não-obesos, enquanto prolongamento relevante da t1/2 (3,2 para 11,2 h, pPropranolol plasma levels and kinetic disposition may be altered by hypothermic cardiopulmonary bypass (CPB-H). We investigated the potential influence of obesity on propranolol pharmacokinetics in patients undergoing coronary artery bypass grafting employing CPB-H. Fifteen patients, receiving propranolol perorally pre- (10-40 mg, 2-3 times a day) and post-operatively (10 mg, once a day) were distributed in two groups, based on body mass index (BMI), in obese (n = 9, BMI: mean 29.4 kg/m²) and non-obese (n=6, BMI: mean 24.8 kg/m²). A serial of blood samples was collected at the pre- and post-operative periods at time dosing interval (Ä); propranolol plasma levels were measured one day before and after surgery using a high performance liquid chromatographic procedure described previously. PK Solutions software 2.0 was applied to obtain pharmacokinetic parameters. No changes on kinetic parameters as biological half-life (t1/2, p = 0.0625, NS), volume of distribution (Vd/F, p=0.8438, NS) and plasma clearance (CL T/F, p = 0.1563, NS) were obtained for the non-obese patients, while a prolongation of t1/2 (3.2 to 11.2 h, p< 0.0039), an increase on Vd/F (3.0 to 7.7 L/kg,

Farmacocinética da cefuroxima na antibioticoprofilaxia de cirurgia cardíaca

OBJECTIVE: The objective was to investigate the plasma levels and to compare the pharmacokinetics of cefuroxime during and after surgery in adult patients with elective indication for coronary artery bypass grafting. METHODS: Seventeen patients received three 1.5-g bolus IV doses of cefuroxime, one every 12 hrs. Serial blood samples (3 mL) were collected 1, 3, 6, 9, and 12 hrs after the first dose (given during the intervention) and after the second and third doses (postsurgery). Blood samples were centrifuged and stored frozen until being assayed. For assessment of the cefuroxime plasma levels by liquid chromatography, only 200 µL of plasma were required. Determination of cefuroxime plasma levels was followed by a pharmacokinetic (PK)-modeling using PK Solutions 2.0 software. RESULTS: The kinetic parameters obtained remained unchanged after the first, second, and the third dose as follows: elimination half-life: 1.8 h, 1.9 h, and 1.8 h; clearance: 1.4, 1.5, and 1.5 mL/min/kg, respectively. Additionally, the apparent volume of distribution did not change during and after the intervention: 0.19, 0.25, and 0.22 L/kg, after the first, second, and the third dose, respectively. Since the drug has a low volume of distribution, plasma levels obtained after a 1.5-g IV bolus injection of cefuroxime decreased rapidly due to the high plasma clearance, with a consequent short half-life. CONCLUSIONS: The kinetic disposition of cefuroxime remains unaltered in patients undergoing coronary artery bypass grafting; to reduce the fluctuation in plasma concentrations so that the antibiotic prophylaxis in the peri-operative period is guaranteed, the dose regimen should be reviewed.OBJETIVO: Investigar os níveis plasmáticos e comparar a farmacocinética da cefuroxima durante e após cirurgia de revascularização do miocárdio. MÉTODOS: Dezessete pacientes receberam três doses intravenosas de 1,5 g de cefuroxima, a cada 12 horas. Foram coletadas amostras de sangue nos tempos de 1, 3, 6, 9 e 12 horas após a primeira dose (durante a cirurgia) e após a segunda e terceira dose (administradas após a cirurgia). As amostras de sangue foram centrifugadas e armazenadas congeladas até o momento da análise. Os níveis plasmáticos da cefuroxima foram determinados através de cromatografia líquida, utilizando-se apenas 200 mL de plasma. A determinação da farmacocinética da cefuroxima foi realizada utilizando o software PK-solutions 2.0. RESULTADOS: Todos os parâmetros cinéticos obtidos permaneceram inalterados após a adminstração da 1ª, 2ª e 3ª doses: meia vida de eliminação 1,8h, 1,9h and 1,8h, depuração 1,4, 1,5 and 1,5 mL/min/kg respectivamente. Adicionalmente, o volume aparente de distribuição, não se alterou durante ou após a intervenção: 0,19, 0,25 and 0,22 L/kg, após 1ª, 2ª e 3ª dose, respectivamente. Os níveis plasmáticos obtidos após administração da cefuroxima reduziram rapidamente devido à alta depuração plasmática com conseqüente curta meia-vida plasmática, atingindo valores abaixo da concentração inibitória mínima a partir da 9ª hora da administração. CONCLUSÕES: A disposição cinética da cefuroxima permanece inalterada em pacientes submetidos à cirurgia de revascularização do miocárdio, e com vistas à redução da flutuação no período perioperatório, o regime de dose para a antibioticoprofilaxia poderia ser revisto

Experimental Model of Non-Controlled Hemorrhagic Shock in Pigs

SummaryBackground and objectivesA better understanding of pathophysiologic changes associated to trauma and hemorrhagic shock can help the development of therapies capable of reducing trauma-related mortality. The objective of this study was to describe a model of non-controlled hemorrhagic shock in pigs.MethodsAnimals received ketamine and midazolam as pre-anesthetic medications. Anesthesia was induced with propofol, and tracheal intubation was performed with the animals on spontaneous ventilation. After intubation neuromuscular blockade was performed. Animals were maintained in controlled mechanical ventilation and normocapnia. Anesthesia was maintained with propofol and fentanyl as needed. Saline was infused during the entire preparation period.MonitoringCardioscope, pulse oximeter, invasive blood pressure, volumetric catheter in the pulmonary artery, and urine output by cystostomy were used. Experimental model: after the initial recording of hemodynamic, metabolic, and coagulation variables, right subcostal incision and left lobe liver biopsy were performed. Anesthetic infusion was reduced while the infusion of saline was interrupted. An incision 12cm long 2cm deep was performed in the right liver lobe followed by digital divulsion of the wound. During the hemorrhagic phase, an aspiration probe was placed close to the wound and the volume of aspirated blood was recorded. When mean arterial pressure reached 40mmHg and bleeding was above 700mL the intervention phase was initiated according to the type of study.ConclusionThe development of experimental models to reduce high mortality and costs related to trauma is important

Intrathecal Morphine Plus General Anesthesia in Cardiac Surgery: Effects on Pulmonary Function, Postoperative Analgesia, and Plasma Morphine Concentration

OBJECTIVES: To evaluate the effects of intrathecal morphine on pulmonary function, analgesia, and morphine plasma concentrations after cardiac surgery. INTRODUCTION: Lung dysfunction increases morbidity and mortality after cardiac surgery. Regional analgesia may improve pulmonary outcomes by reducing pain, but the occurrence of this benefit remains controversial. METHODS: Forty-two patients were randomized for general anesthesia (control group n=22) or 400 µg of intrathecal morphine followed by general anesthesia (morphine group n=20). Postoperative analgesia was accomplished with an intravenous, patient-controlled morphine pump. Blood gas measurements, forced vital capacity (FVC), forced expiratory volume (FEV), and FVC/FEV ratio were obtained preoperatively, as well as on the first and second postoperative days. Pain at rest, profound inspiration, amount of coughing, morphine solicitation, consumption, and plasma morphine concentration were evaluated for 36 hours postoperatively. Statistical analyses were performed using the repeated measures ANOVA or Mann-Whiney tests (*p<0.05). RESULTS: Both groups experienced reduced FVC postoperatively (3.24 L to 1.38 L in control group; 2.72 L to 1.18 L in morphine group), with no significant decreases observed between groups. The two groups also exhibited similar results for FEV1 (p=0.085), FEV1/FVC (p=0.68) and PaO2/FiO2 ratio (p=0.08). The morphine group reported less pain intensity (evaluated using a visual numeric scale), especially when coughing (18 hours postoperatively: control group= 4.73 and morphine group= 1.80, p=0.001). Cumulative morphine consumption was reduced after 18 hours in the morphine group (control group= 20.14 and morphine group= 14.20 mg, p=0.037). The plasma morphine concentration was also reduced in the morphine group 24 hours after surgery (control group= 15.87 ng.mL-1 and morphine group= 4.08 ng.mL-1, p=0.029). CONCLUSIONS: Intrathecal morphine administration did not significantly alter pulmonary function; however, it improved patient analgesia and reduced morphine consumption and morphine plasma concentration

Early administration of fibrinogen concentrate in patients with polytrauma with thromboelastometry suggestive of hypofibrinogenemia: A randomized feasibility trial

OBJECTIVE: To evaluate the clinical effects of early administration of fibrinogen concentrate in patients with severe trauma and hypofibrinogenemia. METHODS: We conducted an open randomized feasibility trial between December 2015 and January 2017 in patients with severe trauma admitted to the emergency department of a large trauma center. Patients presented with hypotension, tachycardia, and FIBTEM findings suggestive of hypofibrinogenemia. The intervention group received fibrinogen concentrate (50 mg/kg), and the control group did not receive early fibrinogen replacement. The primary outcome was feasibility assessed as the proportion of patients receiving the allocated treatment within 60 min after randomization. The secondary outcomes were transfusion requirements and other exploratory outcomes. Randomization was performed using sequentially numbered and sealed opaque envelopes. ClinicalTrials.gov: NCT02864875. RESULTS: Thirty-two patients were randomized (16 in each group). All patients received the allocated treatment within 60 min after randomization (100%, 95% confidence interval, 86.7%-100%). The median length of intensive care unit stay was shorter in the intervention group (8 days, interquartile range [IQR] 5.75-10.0&nbsp;vs. 11 days, IQR 8.5-16.0;&nbsp;p=0.02). There was no difference between the groups in other clinical outcomes. No adverse effects related to treatment were recorded in either group. CONCLUSION: Early fibrinogen replacement with fibrinogen concentrate was feasible. Larger trials are required to properly evaluate clinical outcomes