Ventilación mecánica en el paciente con lesión cerebral aguda / Mechanical ventilation in patients with acute brain injury

In about20 percent of patients admitted to an Intensive Care Unit (ICU) the indica-tion of mechanical ventilation (MV) is a neurological disease. These patients have a prolonged MV stay and high mortality. The appropriate use of MV in patients with acute brain injury (ABI) is critica! considering that MV by itself is oble to induce or worsen an underlying lung injury. Patients with ABI have a higher risk to develop pulmonary complications. During endotracheal intubation the activation of airway reflexes should beprevented, because they may increase intracranialpressure. Tracheostomy is indicated to improve airway management and it is performed in about 33 percent of these patients. Indications for MV are loss of spontaneous respira-tory effort, changes in lung compliance, gas exchange impairment and ventilatory failure due to muscle fatigue or neuromuscular junction dysfunction. During MV, hypoxemia should be avoided. The pC0(2) level has a critica! role in cerebral blood flow regulation; therefore a normal pCO must be maintained in order to guarantee an optimal cerebral blood flow. Despite that, hypocapnia has been used in patients with increased intracranial pressure, at the present it is not recommended. Its use should be limited to the emergency management of intracranial hypertension, while the underlying cause is beingtreated. Non-conventional ventilatory modes asprone position ventilation, high-frequency oscillatory ventilation and extracorporeal C02 removal can be used in patients with ABI. All ofthem have specific risks and should be employed cautiously This paper reviews upper airway management and MV in patients with acute brain injury.

Ajuste a la ventilación mecánica guiado por curvas presión-volumen de flujo lento en pacientes con síndrome de distress respiratorio agudo e injuria pulmonar aguda / Mechanical ventilatory parameters guided by the low flow pressure-volume curve in patients with acute lung injury/acute respiratory distress syndrome

Background: Mechanical ventilation may contribute to lung injury and then enhance systemic inflammation. Optimal ventilatory parameters such as tidal volume (V T) and positive end expiratory pressure (PEEP) can be determined using different methods. Low flow pressure volume (P/V-LF) curve is a useful tool to assess the respiratory system mechanics and set ventilatory parameters. Aim: To set V T and PEEP according P/V-LF curve analysis and evaluate its effects on gas exchange and hemodynamic parameters. Materials and methods: Twenty seven patients underwent P/V-LF within the first 72 hours of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). P/V-LF curves were obtained from the ventilator and both lower and upper inflexion points determined. Gas exchange and hemodynamic parameters were measured before and after modifying ventilator settings guided by P/V-LF curves. Results: Ventilatory parameters set according P/V-LF curve, led to a rise of PEEP and reduction of V T: 11.6±2.8 to 14.1±2.1 cm H2O, and 9.7±2.4 to 8.8±2.2 mL/kg (p <0.01). Arterial to inspired oxygen fraction ratio increased from 158.0±66 to 188.5±68.5 (p <0.01), and oxygenation index was reduced, 13.7±8.2 to 12.3±7.2 (p <0.05). Cardiac output and oxygen delivery index (IDO2) were not modified. Demographic data, gas exchange improvement and respiratory system mechanics showed no significant difference between patients with extra-pulmonary and pulmonary ALI/ARDS. There was no evidence of significant adverse events related with this technique. Conclusion: P/V-LF curves information allowed us to adjust ventilatory parameters and optimize gas exchange without detrimental effects on oxygen delivery in mechanically ventilated ALI/ARDS patients.

Síndrome compartimental del abdomen en el paciente crítico / Abdominal compartment syndrome in critically ill patients

En la última década se ha observado un incremento de la literatura disponible sobre hipertensión intrabdominal (HIA) y síndrome compartimental del abdomen. Dado las importantes implicancias fisiopatológicas del aumento de la presión intrabdominal (PIA) en la función de órganos dentro y fuera del abdomen, este tópico es y será trascendente en los próximos años para una población de pacientes críticamente enfermos tanto neonatales, pediátricos como adultos. El objetivo de la presente revisión es efectuar una puesta al día sobre definiciones, epidemiología, metodología de medición, implicancias fisiopatológicas, hallazgos radiológicos y opciones terapéuticas. Mensajes claves a conocer por el lector son: (1) el índice de masa corporal y la resucitación con volumen predicen el desarrollo de HIA; (2) la HIA aumenta las presiones intratorácicas, intracraneana y de llenado cardíaco, y disminuye la compliance ventricular izquierda, de la pared torácica y total del sistema respiratorio; (3) la HIA causa atelectasia y aumenta el contenido de agua extravascular pulmonar; (4) la mejor presión positiva de fin de espiración (PEEP) debe ser indicada para contrarrestar la HIA; (5) estrategias de ventilación protectora deben de estar orientadas por DPpl (presión plateau-PIA); (6) presiones transdiafragmáticas e indicadores volumétricos reflejan mejor la precarga; (7) la HIA es un predictor independiente de falla renal aguda; (8) la HIA gatilla translocación bacteriana y desarrollo de síndrome de falla orgánica múltiple; (9) se recomienda la monitorización de la presión de perfusión abdominal en casos seleccionados.

Características de la enfermedad cerebrovascular en un Servicio de Cuidados Intermedios Neurológicos, en Chile. Análisis de 459 pacientes consecutivos / Cerebrovascular disease in a Neurologic Intermediate Care Unit in Chile. Analysis of 459 consecutive patients

Background: Stroke is the second cause of mortality and the first cause of morbidity in Chile and worldwide. Nowadays there is a major interest in introducing new therapies applying evidence based medicine for these patients. Aim: To describe the clinical profile of patients attended after a stroke, to determine stroke subtypes and their risk factors. Material and methods: Retrospective review of clinical records of 459 patients (mean age 65±48 years, 238 female) that were admitted to our unit during a period of 37 months. Results: Sixty three percent of patients had an ischemic stroke, 14% had an hemorrhagic stroke, 15% had a transient ischemic attack, 2% had a cerebral venous thrombosis and 6% a subarachnoidal hemorrhage. The global mortality was 1%. Seventy percent of patients had a history of high blood pressure. Conclusions: The most common type of stroke is ischemic and high blood pressure is the main risk factor.

Adición de un cortocircuito arterio-venoso durante el soporte vital extracorpóreo veno-arterial de un paciente con síndrome cardiopulmonar por Hantavirus: Caso clínico / Addition of an arterio-venous shunt during veno-arterial extracorporeal life support in a patient with Hantavirus pulmonary syndrome

A subgroup of patients infected with the Hantavirus develops a pulmonary syndrome (HPS) characterized by severe acute respiratory failure and myocardial depression, that has a high mortality rate. Extracorporeal life support (ECLS) could be a valuable therapeutic tool in such patients. We report a 24 years old male with HPS that was successfully managed when an arterio-venous shunt was added to a conventional veno-arterial ECLS technique. Precise criteria have been developed to predict which patients should be considered for this treatment.

Volumen sanguíneo intratorácico versus presión arterial de oclusión pulmonar como estimadores de precarga cardíaca en pacientes críticos / Intrathoracic blood volume versus pulmonary artery occlusion pressure as estimators of cardiac preload in critically ill patients

Background:Monitoring of cardiac preload by determination of pulmonary artery occlusion pressure (PAOP) has been traditionally used to guide fluid therapy to optimize cardiac output (CO). Since factors such as intrathoracic pressure and ventricular compliance may modify PAOP, volumetric estimators of preload have been developed. The PiCCO system is able to measure CO and intrathoracic blood volume (ITBV) by transpulmonary thermodilution. Aim: To compare a volumetric (ITBV) versus a pressure (PAOP) determination to accurately estimate cardiac preload in severely ill patients. Patients and Methods: From June 2001 to October 2003, 22 mechanically ventilated patients with hemodynamic instability underwent hemodynamic monitoring with pulmonary artery catheter (PAC) and PiCCO system. ITBV index (ITBVI), PAOP and CI were measured simultaneously by both methods. One hundred thirty eight deltas (D) were obtained from the difference of ITBVI, PAOP, CI-PAC and CI-PiCCO between 6-12 am and 6-12 pm. Linear regression analysis of DITBVI versus Ð CI-PiCCO and Ð PAOP versus DCI-PAC were made. Results: Mean age of patients was 60.8 ± 19.4 years. APACHE II was 23.9 ± 7. Fifteen patients met criteria for acute respiratory distress syndrome (ARDS). Delta ITBVI significantly correlated with DCI-PiCCO (r=0.54; 95% confidence interval = 0.41-0.65; p <0.01). There was no correlation between DPAOP and Ð CI-PAC. Conclusion: ITBVI correlated better with CI than PAOP, and therefore it seems to be a more accurate estimator of preload in unstable, mechanically ventilated patients.

Vibrio vulnificus: una causa infrecuente de shock séptico / Septic shock caused by vibrio vulnificus: report of 1 case

Vibrio vulnificus is a lactose positive Gram negative rod that lives in warm seas and can infect wounds and produce sepsis. Its infection is acquired after eating oysters or other filtering marine organisms. We report a 53 years old diabetic male who started with fever after a voyage to Central America. He was admitted febrile, hipotense, dehydrated and polypneic. Painful erythematous lesions and lumps were observed in his upper and lower limbs. After 72 hours of evolution, the lesions became violaceous, with crepitating vesicles full of hemorrhagic exudate. He developed a renal failure and a disseminated intravascular coagulation. Blood cultures demonstrated the presence of Vibrio vulnificus and the patient died 68 hours after admission

Monitoreo de la volemia y el agua pulmonar extravascular en UCI / Monitoring of blood volume and the extravascular lung water in intensive care units

Traditionally Pulmonary wedge pressure (PWP) determination with Swan-Ganz catheter has been the gold standard to estimate ventricular preload in critically ill patients. However, the correlation between PWP and left ventricular telediastolic volume is poor, and the tecnique does not allow any estimation of extravascular lung water (EVLW). In the last years, several techniques have been developed to improve assessment of intra and extravascular volumes. Two tracers transcardiopulmonary dilution method was developed by Pearce et al in the early 60ïs. It used a thermal tracer to estimate intrathoracic total volumen (ITTV), and a colorimetric tracer for estimting intrathoracic blood volume (ITBV). The difference between ITTV and ITBV is called EVLW. Recently, the technique has been simplified to use just the thermal tracer. The Pulse Contour Cardiac Output computer (PiCCO, Pulsion Medizintechnik, Germany), allows a continous measurement of cardiac output and an intermittent measurement of ITTV, ITBV and EVLW. The use of this new technique could improve patient management, allowing optimal fluids administration without producing lung edema. Besides the PiCCO computer, both a standard central venous line in an upper body vein and a specially designed femoral artery line to measure thermal tracer dissipation are required. Preliminary experience has shown that it is a reliable method, with low morbidity and easy implementation, and may be a promising and useful tool in critical care patients

Ventilación con presión positiva no invasiva, VPPNI, en pacientes con insuficiencia respiratoria aguda hipoxémica / Noninvasive ventilation with positive pressure in patients with acute hypoxemic respiratory failure

Quisimos evaluar la aplicabilidad y eficacia de la ventilación con presión positiva no invasiva (VPPNI) en pacientes con insuficiencia respiratoria aguda (IRA) hipoxémica y aumento del trabajo respiratorio. En un periodo de 10 meses evaluamos a 64 pacientes que ingresaron a nuestro servicio con el diagnóstico de IRA y signos de fatiga muscular, en ausencia de patología crónica. Fueron considerados no aptos para VPPNI quienes tuvieran compromiso de conciencia importante, inestabilidad hemodinámica o más de dos órganos en falla, cirugía reciente de esófago, estómago o duodeno, hemorragia digestiva alta activa, distensión abdominal importante o dificultad en el manejo de secreciones. Luego de aplicar los criterios de exclusión, 14 (23 por ciento) pacientes fueron sometidos a VPPNI por un periodo de 1 a 9 días. La Pa/FiO2, sin cambios significativos en la PaCO2 y frecuencia respiratoria. En 5 pacientes (36 por ciento) fracasó el método, de los cuales 2 fallecieron. Un paciente presentó una escara nasal. Por su mínima invasividad y fácil aplicación, la VPPNI debe ser considerada precozmente en todo paciente con IRA hipoxémica con buen nivel de conciencia y que preserve su ventilación espontánea

Efecto agudo de dobutamina y amrinona sobre la hemodinamia y perfusión esplácnica de pacientes en shock séptico / Acute effect of dobutamine and amrinone on hemodynamics and splanchnic perfusion in septic shock patients

Background: Vasoactive drugs used in the reanimation of septic patients, can modify splanchnic perfusion. Aim: To compare the effects of dobutamine and amrinone on gastric intramucosal pH (pHi), lactate levels and hemodynamics in surgical patients with compensated septic shock. Patients and methods: Fourteen postoperative patients with abdominal sepsis and compensated septic shock (pHi <7.32 or lactate >2.5 mmol/l) were studied in a prospective, randomized, unblinded study. Patients were randomized to receive (Group 1, n=7) dobutamine at 5 µg/Kg/min or (Group 2, n=7) amrinone at 5 µg/Kg/min. Hemodynamic data, arterial lactate and pHi were measured before and 30, 60 and 120 minutes after starting drug infusion. Results: Both drugs were associated with a decrease in lactate levels. Dobutamine infusion, but not amrinone, increased gastric pHi, as well as cardiac index and oxygen delivery. Conclusions: An improvement in gastric pHi associated with an increase in oxygen delivery, was observed with dobutamine. Amrinone showed no effect at the fixed, low dose used in the study

Efecto de las catecolaminas sobre la perfusión esplácnica en la sepsis / Effects of catecholamines on splanchnic perfusion in sepsis

Splanchnic ischemia is frequent in sepsis and septic shock and is related to impairment in intestinal permeability, derangement in mucosal barrier functions and translocation of proinflammatory mediators. These changes can contribute to the pathogenesis of multiple organ failure. Vasoactive drugs such as dobutamine and dopexamine can improve splanchnic perfusion and gastric intramucosal pH during sepsis. However, contradictory results have been obtained with dopamine and norepinephrine. On the other hand, epinephrine further impairs splanchnic perfusion. In view of the contradictory effects of different vasoactive drugs, gastric tonometry must be measured during their use, to find the optimal drug combination that optimizes splanchnic blood flow

Ventriculectomía parcial izquierda en un paciente con miocardiopatía dilatada terminal: ¿una alternativa para el trasplante cardíaco? / Partial left ventriculectomy for end stage dilated cardiomyopathy: report of one case

We present a case of a 60 year old male with end stage dilated cardiomyopathy in NYHA functional class IV in whom a partial left ventriculectomy was performed, a new surgical procedure developed in Brazil and done for the first time in Chile. Left ventricular size reduction produced an objective improvement on echocardiographic parameters of left ventricular function as well as in patient's NYHA functional class in the early post operative period