Achievement of effective cardiopulmonary trauma surgical skills training throughout the incorporation of a low-cost and easy to implement pulsatile simulation model.

OBJECTIVES: . In the last decade, concern regarding the preparedness of general surgery graduates to effectively manage thoracic trauma cases has been raised. However, due to limited availability and elevated costs, access to cardiopulmonary trauma simulation models is limited. This article describes our experience implementing a low-cost blended ex vivo tissue-based simulation model using animal by-products that incorporates pump perfusion and ventilation. DESIGN: . Firstly, for validation purposes 8 junior residents, 8 recently graduated general surgeons, and 3 cardiothoracic surgery attendings from Pontificia Universidad Católica de Chile Clinical Hospital were recruited. Proficiency in performing a pulmonary tractotomy and a myocardial injury repair was assessed with global and specific rating scales. Secondly, to evaluate the effectiveness of the model as a learning tool, 16 general surgery residents from different programs across the country were recruited receiving intensive, personalized training on the models. Proficiency was measured before and after the training. RESULTS: . For the validation phase, significant differences among groups according to the previous level of expertise were shown, and therefore construct validity was established. The results of the second phase showed a significant overall improvement in participant's performance. CONCLUSION: . Effective training and assessment for advanced surgical skills in cardiothoracic trauma can be achieved using a low-cost pulsatile simulation model.

Transplantation of Human Amniotic Membrane over the Liver Surface Reduces Hepatic Fibrosis in a Cholestatic Model in Young Rats.

PURPOSE: Biliary atresia precedes liver cirrhosis and liver transplantation. Amniotic membrane (AM) promotes tissue regeneration, inhibits fibrosis, and reduces inflammation. Here, we test amniotic membrane potential as a therapeutic tool against cholestatic liver fibrosis. METHODS: Three groups of rats were used: sham surgery (SS), bile duct ligature (BDL), and bile duct ligature plus human amniotic membrane (BDL + AM). After surgery, animals were sacrificed at different weeks. Biochemical and histopathological analyses of liver tissue were performed. Collagen was expressed as a percentage of total liver tissue area. qPCR was performed to analyse gene expression levels of transforming growth factor-ß1 (Tgfb1) and apelin (Apln). Statistical analysis performed considered p < 0.05 was significant. RESULTS: Groups undergoing BDL developed cholestasis. Biochemical markers from BDL + AM group improved compared to BDL group. Ductular reaction, portal fibrosis, and bile plugs were markedly reduced in the BDL + AM group compared to BDL group. Collagen area in BDL + AM group was statistically decreased compared to BDL group. Finally, expression levels of both Apln and Tgfb1 mRNA were statistically downregulated in BDL + AM group versus BDL group. CONCLUSION: AM significantly reduces liver fibrosis in a surgical animal model of cholestasis. Our results suggest that AM may be useful as a therapeutic tool in liver cirrhosis.

Surgical acquired aganglionosis: myth or reality?

PURPOSE: A number of patients operated on for Hirschsprung disease continue to have constipation and abdominal distension for years after surgery. Some authors have proposed that ischemia during surgery may induce secondary aganglionosis. The aim of the present study was to study the effects of ischemia on the enteric nervous system of sigmoid colon in an animal model. METHODS: A surgical model of colonic ischemia was created. 34 adult Sprague-Dawley rats underwent a laparotomy where the marginal arterioles of the sigmoid colon were ligated. After that, a section in the middle segment of the sigmoid colon was performed followed by an anastomosis. The presence of ischemia was assessed by measurement of visible light spectroscopy tissue oximetry and histological examination. Colonic function was assessed by evaluation of stool weight. Rats were killed at 1, 8 and 12 weeks after the operation. 12 rats were sham-operated. Enteric nervous system was evaluated by means of immunohistochemistry with NGFR p75. Quantitative analysis of the number of ganglia and ganglion cells in the myenteric plexus was performed. RESULTS: The surgical model of colonic ischemia significantly decreased tissue oxygenation (pre-surgical = 54.69 ± 7.32 %; post-surgical = 27.37 ± 9.2 %; p < 0.001). There was no disturbance in body-weight gaining in experimental groups and daily stool output did not vary after surgery (pre-surgical = 4.24 ± 0.94 g; post-surgical = 3.82 ± 1 g; p = 0.09). All experimental groups showed persistent ganglia. However, there was a significant decrease in the number of ganglia in all the experimental groups compared to control (1w: 45.91 ± 7.66; 8w: 44.17 ± 10.56; 12w: 36.17 ± 15.06 vs control: 56.88 ± 8.66; p < 0.01). The number of total ganglion cells was significantly reduced only in the experimental group killed at week 12 compared to control (1w: 539 ± 167.58; 8w: 488.58 ± 154.41; 12w: 343.94 ± 161.91 vs control: 513.96 ± 126.97; p < 0.01). The rate of ganglion cells per ganglia was significantly higher in the groups killed at week 1 and 8 versus control group (1w: 11.63 ± 2.53; 8w: 11.11 ± 2.56; 12w: 9.34 ± 1.16 vs control: 9.02 ± 1.81; p < 0.05). CONCLUSION: Long-term follow-up after surgically induced colonic ischemia in the rat showed a decreased number of ganglion cells and ganglia. Nevertheless, it did not produce aganglionosis.

Tidal volume is a major determinant of cyclic recruitment-derecruitment in acute respiratory distress syndrome.

BACKGROUND: Overdistension and cyclic recruitment-derecruitment contribute to ventilator-induced lung injury. High tidal volumes are thought to increase mortality mainly by inducing overdistension. However, experimental evidence suggests that tidal volume (VT) may also influence cyclic recruitment-derecruitment. Our main goal was to determine whether high tidal volumes increase cyclic recruitment-derecruitment in acute respiratory distress syndrome (ARDS) patients, as measured by dynamic computed tomography (CT). METHODS: We studied 9 ARDS patients with diffuse attenuations on CT who underwent a protocol including 2 ventilatory modes: (a) VT 6 mL/kg, respiratory rate 30/min, PEEP 9 cmH2O, (b) VT 12 mL/kg, respiratory rate 15/min, PEEP 9 cmH2O. A dynamic computed tomography of 8 seconds on a fixed transverse region was performed during each ventilator mode. Cyclic recruitment-derecruitment was determined as non-aerated tissue variation between inspiration and expiration and was expressed as % of lung tissue weight. RESULTS: VT 12 mL/kg exhibited less non-aerated tissue at expiration compared to VT 6 ml/kg (40.15 [35.94-56.00] and 45.31 [37.95-59.32], respectively, P<0.05). However, VT 12 ml/kg increased cyclic recruitment-derecruitment compared to VT 6 mL/kg (7.32 [6.58-9.29] mL/kg vs. 4.51 [3.42-5.75] mL/kg, P<0.01). Tidal hyperinflation was also larger at VT 12 mL/kg (0.55 [0.27-2.24] vs. 0.24 [0.18-0.83], P<0.01). CONCLUSION: High tidal volume is a major determinant of cyclic recruitment-derecruitment in ARDS patients with diffuse attenuations.

Tumor de Wilms: asociación de complicaciones quirúrgicas y hallazgos clínicos e imagenológicos / Wilms' tumor: surgical complications and clinical-imaging findings

Los pilares del tratamiento del Tumor de Wilms son la cirugía y la quimioterapia y, según la etapificación de la enfermedad, la radioterapia. En Chile, el protocolo terapéutico contempla definir si el tumor es resecable o irresecable al momento del diagnóstico de acuerdo a los hallazgos imagenológicos. Pensamos que debería establecerse elementos clínicos claros que permitan discernir objetivamente la resecabilidad tumoral en el nefroblastoma. Se realiza revisión de fichas clínicas y exámenes imagenológicos (ecografía y tomografía axial computarizada(Tac)) de pacientes tratados en el Hospital Roberto del Río entre julio 1995 y julio 2003 por uno de los autores. Una vez tabulados estos datos se entregaron a dos cirujanos oncólogos quienes por separado y en forma independiente y ciega según estos elementos clínicos debían considerarar si el tumor era resecable o irresecable. El grado de acuerdo entre los cirujanos se midió mediante el empleo del Indice Kappa. Las determinaciones de significación estadística se realizaron mediante prueba de Fisher_Irwing. Los índices Kappa de concordabilidad entre los 2 cirujanos observadores fue Clínica = 0.611; Ecografía = 0.87; Tac = 0.72. La diferencia estadística en la concurrencia de complicaciones quirúrgicas entre los 14 pacientes en que el tratamiento quirúrgico se realizó en la oportunidad de consenso y aquellos en los que no hubo acuerdo entre los cirujanos evaluadores A y B y la indicación del equipo fue significativa ( p= 0.0083 ). Proponemos los siguientes criterios predictivos de complicaciones en el tratamiento quirúrgico del Tumor de Wilms: Un tumor renal unilateral que aumente en 20 por ciento ó más el volumen renal para ese paciente comparándolo con el contralateral será considerado irresecable, si además se agregan al menos dos de los hallazgos clínicos que se mencionan a continuación: No movilidad del tumor en la palpación abdominal Circulación abdominal colateral marcada Tumor que traspasa la línea media.

[Spontaneous rhythmic contractions of human placental vessels: is it an evidence for a physiological pacemaker in blood vessels?]. / Actividad rítmica espontánea en vasos de placenta humana: un marcapaso fisiológico en los vasos sanguíneos?

BACKGROUND: Placental vessels are not innervated. Therefore the vasomotor activity and vascular tone is not regulated by the nervous system. AIM: To assess the existence of pacemaker mechanisms related to rhythmic motor activity of blood vessels. MATERIAL AND METHODS: Isometric contractions of rings from umbilical and chorionic vessels of term human placentas were monitored. RESULTS: Recordings of the circular layer of chorionic and umbilical vessels revealed rhythmic spontaneous contractions with a frequency of 1.4 +/- 0.05 cycles/min, the duration of each cycle was 42.8 +/- 0.24 s (n = 12). The amplitude of contractions was larger in veins than in arteries, predominating in umbilical vein biopsies, proximal to the fetus. Both the frequency and the amplitude of contractions were relatively constant during the first 30 min. However, after an hour, the frequency declined while the amplitude increased. The absence of the endothelium neither modified the frequency nor the amplitude of the rhythmic activity. Blockage of voltage dependent sodium channels or calcium channels did not alter the frequency of spontaneous contractions, although their magnitude was reduced. Glibenclamide, an ATP-dependent K+ channel blocker or the blockade of gap junctions ablated the frequency and amplitude of spontaneous contractions. CONCLUSIONS: We propose that rhythmic contractions are triggered by pacemaker cells located in the circular layer of the smooth muscle of blood vessels and spread via gap junctions; they likely contribute to the control of blood flow.

[Menometrorrhagia in adolescence]. / Menometrorragia en la adolescencia.

Forty-six patients with the diagnosis of menometrorrhagia, currently under control in the infantile and adolescent unit of Obstetrics and Gynecology Hospital del Salvador. We emphasize that uterine hemorrhage is a frequent emergency during adolescence requiring fully studies. Medical treatment using different hormonal schemes solve the majority of menometrorrhagias. Only a small group require a D & C using the virginal approach. Patients should be controlled during various cycles once bleeding is stopped to avoid relapse and future problems related with anovulation, endometrial hyperplasia or fertility problems.