Browsing by Author "Canessa, Roberto"

Now showing 1 - 9 of 9
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    A fuzzy logic based model computes cardiac output from the radial arterial pressure waveform
    (IEEE, 1994) Urzua Urzua, Jorge; Guarini Hermann, Marcelo Walter; Cipriano, Aldo; Matus Acuña, Marcelo Enrique; Lee, J.; Salinas, C.; Olmedo Hidalgo, Juan Carlos; Lema F., Guillermo; Canessa, Roberto
    An interactive scheme for the development of a fuzzy logic based model has been implemented and applied to build a model that is able to determine cardiac output from radial arterial pressure. It was built using as input radial pressure waveforms from patients in whom cardiac output was simultaneously measured by thermodilution. The scheme was programmed in C language in an Apollo workstation under Unix. Input variables were area under the curve, ratio between systolic and diastolic pressure, and pulse frequency. To determine fuzzy sets and membership functions the authors used 149 pressure waveforms. To test the model, the authors used 6 waveforms not used in building the model. Correlation between predicted cardiac output with measured flow was 0.98.<>
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    Analgesia, sedación y anestesia para cateterismo diagnóstico y/o terapéutico en pacientes pediátricos con cardiopatías congénitas en el Hospital Clínico de la Pontificia Universidad Católica de Chile: algunas recomendaciones
    (2015) Borchert Billik, Evelyn; Lema F., Guillermo; González, K.; Carvajal, C.; López, R.; Canessa, Roberto; Aeschlimann del Río, Nicolás Alejandro; Silva, J. S.; Flores, A.; Springmüller P., Daniel
    Las presentes recomendaciones han sido elaboradas en base a nuestra experiencia, con el propósito de entregar algunas pautas sobre analgesia, sedación y anestesia para cateterismos diagnósticos y/o terapéuticos en pacientes pediátricos con cardiopatías congénitas, de acuerdo a la clasificación de riesgo de los mismos. El propósito de ésta es contribuir a disminuir la incidencia de eventos adversos asociados a morbilidad y mortalidad.
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    Aortic Stenosis and Acquired von Willebrand Disease: Lack of Association
    (W B SAUNDERS CO-ELSEVIER INC, 2011) Carrasco, Esperanza; Lopez, Rodrigo; Rattalino, Marcos; Lema, Guillermo; Pereira, Jaime; Canessa, Roberto; Zalaquett, Ricardo; Carvajal, Claudia; Carrasco, Paulo
    Objectives: The association between aortic stenosis (AS) and acquired von Willebrand disease type 2A has been described. It may be present in up to 90% of patients with AS. Shear stress has been proposed as the underlying mechanism; however, the physiopathology of this condition is not completely understood. No specific treatment has been studied in this specific population besides aortic valve replacement (AVR). As a coadjuvant therapy, some cardiac surgery centers use desmopressin routinely. The authors report the first stage of an ongoing study designed to compare the effects of desmopressin versus placebo in patients with severe AS scheduled for AVR. Because of the different incidences of the acquired von Willebrand type 2A reported in the literature, the first stage was conducted to describe the incidence of this clinical association in the present population, allowing the sample size for the second stage of the study to be obtained.
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    Comparacion de tres metodos de manejo del dolor en pacientes sometidos a revascularizacion miocardica candidatos a tránsito rapido
    (2008) Carvajal F., Claudia; Lema F., Guillermo; Canessa, Roberto; Aeschlimann del Río, Nicolás Alejandro; Merino, Waldo; Mercado Flores, Marcelo Esteban; Muñoz, Rodrigo
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    Decreased Nitric Oxide Products in the Urine of Patients Undergoing Cardiac Surgery
    (W B SAUNDERS CO-ELSEVIER INC, 2009) Lema, Guillermo; Urzua, Jorge; Jalil, Roberto; Canessa, Roberto; Vogel, Andrea; Moran, Sergio; Fajuri, Alejandro; Carvajal, Claudia; Aeschlimann, Nicolas; Jaque, Maria P.
    Objective: Renal vasoconstriction has been blamed as a cause of perioperative renal dysfunction after cardiac surgery. Endothelial function is a critical determinant of vascular tonus, including vasoconstriction. The objective of this study was to establish whether the release of the endothelial vasodilator nitric oxide (NO) or NO products is altered in patients undergoing surgery with cardiopulmonary bypass in 3 different clinical conditions.
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    Endovascular repair of abdominal aortic aneurysm.: Results in 80 consecutive patients
    (2006) Valdes, Francisco; Mertens, Renato; Kramer, Albrecht; Bergoeing, Michel; Marine, Leopoldo; Canessa, Roberto; Huete, Alvaro; Vergara, Jeanette; Valdebenito, Magaly; Rivera, Dixiana
    Background: Endovascular repair of abdominal aortic aneurysms (AAA) avoids laparotomy, shortens hospital stay and reduces morbidity and mortality related to surgical repair allowing full patient recovery in less time. Aim: To report short and long term results of endovascular repair of AAA in 80 consecutive patients treated at our institution. Patients and Methods: Between September 1997 and February 2005, three women and 77 men with a mean age 73.6 +/- 7.7 years with AAA 5.8 +/- 1.0 cm in diameter, were treated. The surgical risk of 38% of patients was grade III according to the American Society Anesthesiologists classification. Each procedure was performed in the operating room, under local or regional anesthesia, with the aid of digital substraction angiography. The endograft was deployed through the femoral artery (83,7016 bifurcated 16.3% tubular graft). A femoro-femoral bypass was required in 11.3% of cases. Follow-tip included a spiral CT scan at 1, 6 and 12 months postoperatively, and then annually). Results. Endovascular repair was successfully completed in 79/80 patients (98.7% technical success). The procedures lasted 147 +/- 71 min. Length of stay in the observation unit was 20.6 +/- 73.5 h. Blood transfusion was required in 10%. Sixty two percent of the patients were discharged before 72 h. One patient died 8 days after surgery due to a myocardial infarction (1.3%. During follow-up (3-90 months), 1 patient developed late AAA enlargement due to a type I endoleak, requiring a new endograft. No AAA rupture was observed. Survival at 4 years was 84.2% (SE = 9.2). Endovascular re-intervention free survival was 82.7% (SE = 9.5). Conclusion: Endovascular surgery allows affective exclusion of AAA avoiding progressive enlargement and/or rupture and is a good alternative to open repair Close and frequent postoperative follow up is mandatory.
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    Oxigenación con membrana extracorpórea en pacientes pediátricos. Comunicación de los 3 primeros casos tratados
    (2005) Kattan, Javier; González, Álvaro; Becker, Pedro; Rodríguez, José; Estay, Alberto; Faunes, Miriam; Fajardo, Christian; Canessa, Roberto
    Extracorporeal membrane oxygenation (ECMO) improves survival in neonatal and pediatric patients with reversible severe respiratory or cardiac failure, in whom intensive treatment fails. Since 1999, a multidisciplinary team is trained to form the first neonatal-pediatric ECMO center in Chile, according to the norms of the Extracorporeal Life Support Organization (ELSO). During 2003 the first three patients were admitted to the program: a male newborn with pulmonary hypertension, a 38 days old female operated for a total anomalous pulmonary venous connection and a 3 months old male with a severe pneumonia caused by respiratory syncytial virus. They remained in ECMO for five, seven and nine days respectively and all survived to the procedure. No neurological complications were observed after one and a half year of follow up. This consolidates the first national neonatal-pediatric ECMO program, associated to ELSO. Up to date, twelve patients have been admitted to the program (Rev Méd Chile 2005; 133: 1065-70).
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    Renal function and cardiopulmonary bypass in pediatric cardiac surgical patients
    (2006) Lema, Guillermo; Vogel, Andrea; Canessa, Roberto; Jalil, Roberto; Carvajal, Claudia; Becker, Pedro; Jaque, Maria Paz; Fajardo, Christian; Urzua, Jorge
    We studied prospectively the perioperative changes of renal function in nine children undergoing cardiac surgery with cardiopulmonary bypass (CPB). Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured with inulin and I-131-hippuran clearances before CPB, during hypo and normothermic CPB, following sternal closure and 1 h postoperatively. Urinary alpha glutathione S-transferase (alpha GS-T) was measured pre- and postoperatively as a marker for tubular cellular damage. Plasma and urine creatinine and electrolytes were measured. Free water, osmolal and creatinine clearances, as well as fractional excretion of sodium (FeNa) and potassium transtubular gradient (TTKG) were calculated. GFR was normal before and after surgery. ERPF was low before and after surgery; it increased significantly immediately after CPB. Filtration fraction (FF) was abnormally elevated before and after surgery; however, a significant decrease during normothermic CPB and sternal closure was found. Alpha GS-T presented a moderate, but nonsignificant increase postoperatively. FeNa also increased in this period, but not significantly. Creatinine, osmolal, free water clearances, as well as TTKG, were normal in all patients pre- and postoperatively. We conclude that there is no evidence of clinically significant deterioration of renal function in children undergoing repair of cardiac lesions under CPB. Minor increases of alpha GS-T in urine postoperatively did not confirm cellular tubular damage. There was no tubular dysfunction at that time.
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    Reparación endovascular de Aneurisma aórtico abdominal: Estudio piloto de endoprótesis Ovation™. Resultados comparativos
    (2011) Valdés, F.; Mertens, R.; Bergoeing Reid, Michel Paul; Mariné M., Leopoldo; Krämer, A.; Vargas, F.; Lema F., Guillermo; Canessa, Roberto; Vergara, J.
    Introducción: Las endoprótesis actuales para tratar aneurismas aórticos (AAA) requieren introductores de alto diámetro (18-25F) y se sustentan excluyendo el aneurisma, mediante la fuerza radial de stents metálicos. Objetivo: prótesis Ovation™ (TriVascular, EEUU) con aquellas disponibles en el mercado. Material y Método: Entre Noviembre 2009 y Agosto 2010 tratamos 47 AAA. En 10 pacientes usamos Ovation™ (Grupo 1). Grupo Control (2): diez pacientes tratados contemporáneamente con endoprótesis comerciales. Ovation™ es tri-modular, de PTFE y nitinol con un stent barbado para fijación supra-renal. Sella bajo las arterias renales mediante 2 anillos llenados con un polímero durante el implante. Usa introductor 13-15F. Usa-Philips-Allura (Best, Holanda). Comparamos: duración del procedimiento, hospitalización y complicaciones. Utilizamos test de Fisher exacto y t de student no pareado. Resultados: Éxito técnico 100%. Sin diferencia entre grupos (edad, sexo, tamaño AAA, riesgo ASA, laboratorio preoperatorio). Tiempo operatorio (hrs): 2,12 ± 0,7 vs. 2,0 ± 0,6 (NS). Estadía postoperatoria (hrs): 44,5 ± 10,7 vs 49,5 ± 32,0 (NS). El cuello del AAA y la permanencia en UTI fueron más cortos en grupo 1 (p= 0,035 y 0,0451). Seguimiento (4,5-12 meses) sin eventos adversos, endofugas tipo I ni III, ni re-intervenciones. Conclusiones: Los resultados con Ovation™ a corto plazo son comparables con los de otras endoprótesis, cumpliendo con estándares de eficacia y seguridad. Ovation ™ navega por vasos pequeños, permite un despliegue preciso y sellado efectivo en cuellos > 7 mm, ampliando el tratamiento endovascular del AAA.