Toward a better quantitative measurement of aortic flow.

Ultrasound investigation of aortic blood flow (ABF) still represents a technically challenging task, because of the complex geometry of such a deep artery. In this paper, we present a unique experimental set-up capable of providing detailed information about blood dynamics in the aorta. The set-up is based on an esophageal probe (EP) connected to a multigate Doppler-processing system. The EP, developed for the noninvasive hemodynamic monitoring of ABF in patients under general anesthesia or in the intensive care area, must be inserted at a thoracic depth where the esophagus and the aorta are nearby and parallel. Doppler processing of pulsed wave echoes in the multigate system provides the distribution of all Doppler frequencies detected along the probe beam axis (spectral profile) in real time. The results of this investigation confirm that flow in the aorta is extremely complex, especially at the level of the aortic arch or in nonphysiologic circumstances. In general, the velocity profiles tend to be flat only during the systolic acceleration, but not during the full cardiac cycle. In most cases, they are asymmetrical, including both positive and negative components. In particular, it is shown that an appropriate positioning of the ultrasound transducer and/or the correct integration of different velocities is mandatory to make reliable ABF measurements.

Simultaneous monitoring of noninvasive hemodynamic profile and capnography for tissue perfusion evaluation.

To study the simultaneous variations of end-tidal CO2 pressure (PetCO2) and aortic blood flow (ABF) during modifications of tissue perfusion, continuous noninvasive hemodynamic monitoring and continuous recording of PetCO2 were performed on 30 patients under general anesthesia and artificial mechanical ventilation. The 30 patients underwent orthopedic surgery on one of the lower limbs using a hemostatic tourniquet. Deflation of the pneumatic tourniquet resulted in a rise of ABF up to 39% (P<0.001), a rise of PetCO2 up to 17% (P<0.001), and a drop of total vascular systemic resistance (TVSR) of 59% (P<0.001). In all cases, the gradient of Paco2-PetCO2 showed mean variations of 1.2±0.5 mmHg. According to these results, the observed variations can not be explained by an alteration of the Ventilation/Perfusion (Vo/Q) ratio alone. It may be suggested that tissue hypoperfusion produced by a tourniquet generates CO2 and other metabolic products accumulation in tissues, which are removed during reperfusion. This would be expected to produce parallel increases in ABF and PetCO2. If the results are confirmed with further studies, rapid variations of PetCO2 during anesthesia may provide a noninvasive means of assessing the quality of global tissue perfusion.

Desflurano y remifentanilo asociados para la inducción inhalatoria, el mantenimiento de la narcoanalgesia y la recuperación rápida postanestésica / Desflurane and remifentanil used in parallel for inhaled induction, the maintenance of the anesthesia and the quickly recuperation post-anesthelic

El protocolo anestésico propuesto abre la posibilidad de utilizar el DES, asociado al REM, para la inducción de la narco analgesia, sin irritación de la vía aérea y sin necesidad de otro narcótico como inductor. Durante el mantenimiento, fuera de las modificaciones hemodinámicas iniciales, facilmente corregidas, la estabilidad fue correcta. La recuperación post anestésica fue rápida, calma y subjetivamente agradable.

Influencia fisiopatológica de la hiperpresión intraperitoneal laparoscópica (Sobre los parámetros hemodinámicos y las variaciones de la PETCO2)

La cirugía laparoscópica no es una técnica moderna. Sus primeras aplicaciones en el animal remontan a 1902 y en el ser humano a 1912. Sin embargo, el desarrollo de nuevos métodos de exploración óptica y la concepción de instrumentos de tamaño reducido, adaptados a la cirugía a "cielo cerrado", han permitido darle una nueva proyección a esta vieja técnica. Los progresos realizados han permitido abordar progresivamente intervenciones quirúrgicas de complejidad creciente, en las cuales algunas veces el balance entre riesgos y beneficios no ha sido suficientemente evaluado