Intraabdominal Pressure Targeted Positive End-expiratory Pressure during Laparoscopic Surgery: An Open-label, Nonrandomized, Crossover, Clinical Trial.

BACKGROUND: Pneumoperitoneum for laparoscopic surgery is associated with a rise of driving pressure. The authors aimed to assess the effects of positive end-expiratory pressure (PEEP) on driving pressure at varying intraabdominal pressure levels. It was hypothesized that PEEP attenuates pneumoperitoneum-related rises in driving pressure. METHODS: Open-label, nonrandomized, crossover, clinical trial in patients undergoing laparoscopic cholecystectomy. "Targeted PEEP" (2 cm H2O above intraabdominal pressure) was compared with "standard PEEP" (5 cm H2O), with respect to the transpulmonary and respiratory system driving pressure at three predefined intraabdominal pressure levels, and each patient was ventilated with two levels of PEEP at the three intraabdominal pressure levels in the same sequence. The primary outcome was the difference in transpulmonary driving pressure between targeted PEEP and standard PEEP at the three levels of intraabdominal pressure. RESULTS: Thirty patients were included and analyzed. Targeted PEEP was 10, 14, and 17 cm H2O at intraabdominal pressure of 8, 12, and 15 mmHg, respectively. Compared to standard PEEP, targeted PEEP resulted in lower median transpulmonary driving pressure at intraabdominal pressure of 8 mmHg (7 [5 to 8] vs. 9 [7 to 11] cm H2O; P = 0.010; difference 2 [95% CI 0.5 to 4 cm H2O]); 12 mmHg (7 [4 to 9] vs.10 [7 to 12] cm H2O; P = 0.002; difference 3 [1 to 5] cm H2O); and 15 mmHg (7 [6 to 9] vs.12 [8 to 15] cm H2O; P < 0.001; difference 4 [2 to 6] cm H2O). The effects of targeted PEEP compared to standard PEEP on respiratory system driving pressure were comparable to the effects on transpulmonary driving pressure, though respiratory system driving pressure was higher than transpulmonary driving pressure at all intraabdominal pressure levels. CONCLUSIONS: Transpulmonary driving pressure rises with an increase in intraabdominal pressure, an effect that can be counterbalanced by targeted PEEP. Future studies have to elucidate which combination of PEEP and intraabdominal pressure is best in term of clinical outcomes.

[None invasive and minimally invasive hemodynamic monitoring in critically ill patients in the emergency department]. / Monitorización hemodinámica no invasiva o mínimamente invasiva en el paciente crítico en los servicios de urgencias y emergencias.

EN: Noninvasive and minimally invasive hemodynamic monitoring systems are used increasingly in emergency departments to provide adequate tissue oxygenation in critically ill patients. Such monitoring assists in the differential diagnosis of shock, the optimization of treatment and assessment of its effects, and the prevention of complications during care. Recent years have seen the development of noninvasive monitors that measure cardiac output continuously by means of electrodes applied to the skin or spectrophotometric sensors. Minimally invasive systems connected to a peripheral artery catheter have also been developed. Conventional hemodynamic monitoring methods alone have sometimes proven inadequate or inefficient in this setting; an example is the measurement of central venous pressure. The clinician therefore needs to understand the advantages and limitations of the different systems for estimating cardiac output before choosing a monitor. Resuscitation protocols that facilitate the fastest possible recovery in emergency care can be established based on the combination of traditional variables, hemodynamic variables, and anatomical and functional data provided by ultrasonography.

ES: La monitorización hemodinámica no invasiva o mínimamente invasiva es una herramienta que se utiliza cada vez más en los servicios de urgencias y emergencias, para garantizar el adecuado aporte de oxígeno a los tejidos en el paciente crítico. Ayuda a establecer el diagnóstico diferencial de las posibles causas de shock y a optimizar el tratamiento, cuantificar sus efectos y evitar las posibles complicaciones derivadas del mismo. Los métodos convencionales de monitorización, por sí solos, se han mostrado insuficientes o poco eficientes, como la presión venosa central (SvcO2), para la evaluación hemodinámica de los pacientes críticos. En los últimos años el desarrollo tecnológico ha permitido disponer de monitores que miden de forma continua el gasto cardiaco (GC) del paciente de forma no invasiva (mediante electrodos cutáneos manguito hinchable digital o sensores de fotoespectrometría) o mínimamente invasiva (mediante la canalización de una arteria periférica). Es importante conocer en la práctica clínica, las ventajas y limitaciones que tienen los sistemas de estimación del GC antes de su aplicación. La combinación de las variables clásicas, las variables hemodinámicas y la información anatómica y funcional que nos proporciona la ecografía va a permitir establecer algoritmos de actuación en los servicios de urgencias y emergencias y sistematizar el proceso de reanimación con la intención de obtener una recuperación más rápida.

Nerve stimulation in regional anesthesia: theory and practice.

There is now an accumulation of extensive and varied experience with the use of electrical stimulation for verifying the close approximation of needle and nerve, and for increasing the corresponding success rate. The application of this experience has been of proven benefit in the teaching of regional anesthetic techniques, in the performing of difficult nerve blocks, and in the use of novel accesses, resulting in decreased morbidity and a reduced requirement for local anesthetic. Nerve stimulation can also be used in uncooperative patients and in anesthetized individuals or patients under the effects of CNS depressors, although the risk of intraneural injection of local anesthetic is not eliminated in such cases. Putting the accummulated knowledge into practice is not simply a question of using electrical stimulation to elicite an artificial muscle contraction. Sound knowledge of the anatomy of the area to be blocked, the muscle territory subsidiary to the nerve in question, the applied neurophysiology, and the pharmacology of the local anesthetic used are needed. This chapter reviews the most important aspects, from nerve anatomy and physiology, to electrical features of the needle, and devices used for the updated clinical application of nerve stimulation in the practice of plexus regional anesthesia.