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INTRODUCTION: In last few years, emphasis was placed in goal-directed therapy in order to optimize patient's hemodynamic status and improve their prognosis. Parameters based on the interaction between heart and lungs have been questioned in situations like low tidal volume and open chest surgery. The goal of the study was to analyze the changes that one-lung ventilation can produce over stroke volume variation and to assess the possible impact of airway pressures and lung compliance over stroke volume variation. METHODS: Prospective observational study, 112 patients undergoing lung resection surgery with one-lung ventilation periods were included. Intravenous fluid therapy with crystalloids was set at 2mL.kg-1.h-1. Hypotension episodes were treated with vasoconstrictive drugs. Two-lung ventilation was implemented with a TV of 8mL.kg-1 and one-lung ventilation was managed with a TV of 6mL.kg-1. Invasive blood pressure was monitored. We recorded the following cardiorespiratory values: heart rate, mean arterial pressure, cardiac index, stroke volume index, airway peak pressure, airway plateau pressure and static lung compliance at 3 different times during surgery: immediately after lung collapse, 30minutes after initiating one-lung ventilation and after restoration of two-lung ventilation. RESULTS: Stroke volume variation values were influenced by lung collapse (before lung collapse14.6 (DS) vs. OLV 9.9% (DS), p < 0.0001); or after restoring two-lung ventilation (11.01 (DS), p < 0.0001). During two-lung ventilation there was a significant correlation between airwaypressures and stroke volume variation, however this correlation lacks during one-lung ventilation. CONCLUSION: The decrease of stroke volume variation values during one-lung ventilation with protective ventilatory strategies advices not to use the same threshold values to determine fluid responsiveness.
RESUMO
The Advanced Cardiac Life Support proposes the use of vasopressor drugs cardiopulmonary resuscitation, with the primary purpose of effectively and early restoration of spontaneous circulation. However, the increased return of spontaneous circulation with vasopressors has not improved neurological outcome at hospital discharge. Adrenaline has traditionally been the main tool of the cardiopulmonary resuscitation guidelines despite the lack of conclusive scientific evidence. Therefore other alternatives were considered at experimental level that has have failed to overcome the clinical results of this drug. In contrast to progress on the standardized management of cardiopulmonary resuscitation, the controversy regarding the effectiveness of vasopressor therapy remains open in the last years due to lack of clinical data to support their usefulness.
El soporte vital avanzado propone el uso de vasopresores durante la resucitación cardiopulmonar, con la finalidad primordial de reestablecer de manera precoz y efectiva la circulación espontánea. Sin embargo, el aumento del retorno a la circulación espontánea asociada a los vasopresores no ha demostrado una mejoría en el pronóstico neurológico al alta hospitalaria. La adrenalina, ha sido tradicionalmente la herramienta principal de las guías de resucitación cardiopulmonar pese a la falta de evidencia científica concluyente. Por ello se han planteado otras alternativas a nivel experimental que no han logrado superar los resultados de este fármaco a nivel clínico. En contraste con los avances respecto al manejo estandarizado de la resucitación cardiopulmonar, el debate con respecto a la efectividad de la terapia vasopresora se mantiene abierto en los últimos años dada la falta de datos clínicos que corroboren su real utilidad.