R. Valero

Normothermic recirculation reduces primary graft dysfunction of kidneys obtained from non-heart-beating donors.

Abstract Our aim was to analyze the short‐ and long‐term function of kidneys procured from non‐ heart‐beating donors (NHBD) by means of three techniques: in situ perfusion (ISP), total body cooling (TBC) and normothermic recirculation (NR). Fifty‐seven potential NHBD were included. Mean warm ischemia time was 68.9 ± 35.6 min. Forty‐four kidneys were obtained from donors perfused with ISP, 8 with TBC, and 8 with NR. Eighteen kidneys (32%) started functioning immediately, 29 (52 %) showed delayed graft function (DGF) and 9 (16%) showed primary non function (PNF). The actuarial graft survival rate was 76.4 % at 1 year and 56 % at 5 years. The patient survival rate was 89.3 % at 5 years. Incidence of DGF and PNF was significantly lower in kidneys perfused with NR than those with ISP or TBC (P < 0.01). Duration of DGF was shorter in kidneys obtained through TBC than in kidneys obtained with ISP (P < 0.05). In conclusion, NR reduces the incidence of DGF and may be considered the method of choice for kidney procurement from NHBD.

Can bispectral index monitoring predict recovery of consciousness in patients with severe brain injury

Background:The probability of recovering consciousness in acute brain-injured patients depends on central nervous system damage and complications acquired during their stay in the intensive care unit. The objective of this study was to establish a relation between the Bispectral Index (BIS) and other variables derived from the analysis of the electroencephalographic signal, with the probability of recovering consciousness in patients in a coma state due to severe cerebral damage. Methods:Twenty-five critically ill, unconscious brain-injured patients from whom sedative drugs were withdrawn at least 24 h before BIS recording were prospectively studied. BIS, 95% spectral edge frequency, burst suppression ratio, and frontal electromyography were recorded for 20 min. The neurologic condition of the patients was measured according to the Glasgow Coma Score (GCS). Patients were followed up for assessment of recovery of consciousness for 6 months after the injury. The studied variables were compared between the group of patients who recovered consciousness and those who did not recover. Their predictive ability was evaluated by means of the Pk statistic. Univariate and multivariate logistic regression was used to model the relation between variables and probability of recovery of consciousness. Cross-validation was used to validate the proposed model. Results:There were statistically significant differences between the group of patients who recovered consciousness and those who did not with respect to BISmax, BISmin, BISmean, and BISrange, frontal electromyography, signal quality index values, and GCSBIS. The Pk (SE) values were 0.99 (0.01) for electromyelography, 0.96 (0.05) for BISmax, 0.92 (0.05) for BISmean, 0.92 (0.06) for BISrange, and 0.82 (0.09) for GCSBIS. The odds ratio for BISmax in the logistic regression model was 1.17 (95% confidence interval, 1.1–1.35). Cross-validation results reported a high-accuracy median absolute cross-validation performance error of 3.06% (95% confidence interval, 1–22.15%) and a low-bias median cross-validation performance error of 0.84% (0.56–2.12%). Conclusions:The study of BIS and other electrophysiologic and clinical variables has enabled construction and cross-validation of a model relating BISmax to the probability of recovery of consciousness in patients in a coma state due to a severe brain injury, after sedation has been withdrawn.

The Effect of Normothermic Recirculation is Mediated by Ischemic Preconditioning in NHBD Liver Transplantation

We have evaluated the involvement of hepatic preconditioning mediators (adenosine, adenosine A1 and A2 receptors) during normothermic recirculation (NR) in a model of liver transplantation from non‐heart‐beating donor (NHBD) pigs.

Evaluation of Ischemic Injury during Liver Procurement from Non-Heart-Beating Donors

The aim of this study was to assess liver viability after different periods of cardiac arrest and the predictive value of two markers of ischemia-reperfusion injury. Methods: A pig liver transplantation model of non-heart-beating donors was studied. Four donor groups were designed; three groups were submitted to different periods of cardiac arrest (20, 30 and 40 min), and the fourth group served as the control group (without cardiac arrest). In the non-heart-beating donor groups, normothermic recirculation was established 30 min prior to total body cooling. Aminotransferase, α-glutathione-S-transferase, and hyaluronic acid determinations as well as liver biopsies, were serially performed. Results: Although hepatocellular function could be preserved after 40 min of cardiac arrest, histological lesions at 5 days were considered irreversible due to the presence of a necrotic biliary tract. An overall significant relationship was found between the time period of cardiac arrest (20, 30 or 40 min) and the levels of hyaluronic acid (p = 0.004) or α-glutathione-S-transferase (p = 0.01) obtained during liver procurement and transplantation. Conclusions: The period of cardiac arrest is the determinant factor of liver viability after liver transplantation from non-heart-beating donors. As early markers of endothelial or hepatocellular damage, hyaluronic acid or α-glutathione-S-transferase levels may help to evaluate the ischemic injury of a potential donor.

L-Arginine reduces liver and biliary tract damage after liver transplantation from non-heart-beating donor pigs

Background. To evaluate whether l-arginine reduces liver and biliary tract damage after transplantation from non heart-beating donor pigs. Methods. Twenty-five animals received an allograft from non-heart-beating donors. After 40 min of cardiac arrest, normothermic recirculation was run for 30 min. The animals were randomly treated with l-arginine (400 mg·kg−1 during normothermic recirculation) or saline (control group). Then, the animals were cooled and their livers were transplanted after 6 hr of cold ischemia. The animals were killed on the 5th day, liver damage was assessed on wedged liver biopsies by a semiquantitative analysis and by morphometric analysis of the necrotic areas, and biliary tract damage by histological examination of the explanted liver. Results. Seventeen animals survived the study period. The histological parameters assessed (sinusoidal congestion and dilatation, sinusoidal infiltration by polymorphonuclear cells and lymphocytes, endothelitis, dissociation of liver cell plates, and centrilobular necrosis) were significantly worse in the control group. The necrotic area affected 15.9±14.5% of the liver biopsies in the control group and 3.7±3.1% in the l-arginine group (P <0.05). Six of eight animal in the control group and only one of eight survivors in the l-arginine group developed ischemic cholangitis (P <0.01). l-Arginine administration was associated with higher portal blood flow (676.9±149.46 vs. 475.2±205.6 ml·min·m−2;P <0.05), higher hepatic hialuronic acid extraction at normothermic recirculation (38.8±53.7% vs. −4.2±18.2%;P <0.05) and after reperfusion (28.6±55.5% vs. −10.9±15.5%;P <0.05) and lower levels of &agr;-glutation-S-transferase at reperfusion (1325±1098% respect to baseline vs. 6488±5612%;P <0.02). Conclusions. l-Arginine administration during liver procurement from non heart beating donors prevents liver and biliary tract damage.

Anesthetic management of surgical neuroendoscopies: usefulness of monitoring the pressure inside the neuroendoscope.

Neuroendoscopic procedures are increasing in frequency in neurosurgical practice. We describe the anesthetic technique and the perioperative complications found in 100 neuroendoscopic interventions performed at our institution. Cranial tumor biopsy or retrieval (62%) and cisternostomy for hydrocephalus (33%) were the most frequent indications for neuroendoscopy. The mortality rate was low (1%). Intraoperative complications occurred in 36 patients, with arterial hypertension being the most frequent (53%). Postoperative complications occurred in 52 patients; anisocoria (31%) and delayed arousal (29%) were the most frequent. The pressure inside the endoscope was monitored intraoperatively in the last 47 patients. A saline-filled catheter from a pressure transducer connected to the neuroendoscopy system was used for pressure monitoring. We recorded the highest peak of pressure values measured during each procedure. Twenty-three patients (49%) had peak pressure values >30 mm Hg, 12 patients (25%) >50 mm Hg, and 3 patients >100 mm Hg. Only one patient had hemodynamic changes occurring simultaneously with the pressure changes. We found an association between pressure inside the endoscope >30 mm Hg and postoperative (P = .003) but not intraoperative complications. A relationship was found between surgical duration and postoperative complications (P = .002). Neither the pressure inside the endoscope or the intraoperative morbidity were related to surgical duration. We conclude that there may be a high rate of postoperative complications after neuroendoscopies, namely, new neurologic deficits. High pressure levels inside the endoscope during neuroendoscopic procedures can occur without hemodynamic warning signs. Pressure values >30 mm Hg are associated with postoperative morbidity, especially unexpected delayed recovery. Measuring the pressure inside the endoscope is technically easy and might be beneficial if performed in all neuroendoscopic procedures. Reducing the incidence of episodes of high peak pressure values might decrease the rate of postoperative complications.

Modeling of the Sedative and Airway Obstruction Effects of Propofol in Patients with Parkinson Disease undergoing Stereotactic Surgery

Background Functional stereotactic surgery requires careful titration of sedation since patients with Parkinson disease need to be rapidly awakened for testing. This study reports a population pharmacodynamic model of propofol sedation and airway obstruction in the Parkinson disease population. Methods Twenty-one patients with advanced Parkinson disease undergoing functional stereotactic surgery were included in the study and received propofol via target-controlled infusion to achieve an initial steady state concentration of 1 &mgr;g/ml. Sedation was measured using the Ramsay Sedation Scale. Airway obstruction was measured using a four-category score. Blood samples were drawn for propofol measurement. Individual pharmacokinetic profiles were constructed nonparametrically using linear interpolation. Time course of sedation and respiratory effects were described with population pharmacodynamic models using NONMEM. The probability (P) of a given level of sedation or airway obstruction was related to the estimated effect-site concentration of propofol (Ce) using a logistic regression model. Results The concentrations predicted by the target-controlled infusion system generally exceeded the measured concentrations. The estimates of C50 for Ramsay scores 3, 4, and 5 were 0.1, 1.02, and 2.28 &mgr;g/ml, respectively. For airway obstruction scores 2 and 3, the estimates of C50 were 0.32 and 2.98 &mgr;g/ml, respectively. Estimates of ke0 were 0.24 and 0.5 1/min for the sedation and respiratory effects, respectively. Conclusions The pharmacokinetic behavior of propofol in patients with Parkinson disease differs with respect to the population from which the model used by the target-controlled infusion device was developed. Based on the results from the final models, a typical steady state plasma propofol concentration of 0.35 &mgr;g/ml eliciting a sedation score of 3 with only minimal, if any, airway obstruction has been defined as the therapeutic target.

Comparison of the LMA Supreme™ with the LMA Proseal™ for airway management in patients anaesthetized in prone position

BACKGROUND The laryngeal mask airway (LMA) has been successfully used in patients in the prone position either for rescue or elective airway management. The reusable Proseal™ LMA (PLMA) and the single use Supreme™ LMA (SLMA) have been reported to be suitable for this purpose but few comparative data are available. In this study, we compared the clinical use of both devices in adult patients anaesthetized in the prone position. METHODS One hundred and twenty patients undergoing surgery in the prone position were randomized to receive either the PLMA or the SLMA for airway management. Patients positioned themselves in the prone position and after pre-oxygenation, anaesthesia was induced using a target-controlled i.v. infusion of propofol and remifentanil. All PLMAs and SLMAs were inserted by experienced anaesthetists using a guided and a standard technique respectively. Ease of facemask ventilation, time and number of attempts needed for insertion, quality of ventilation, airway seal pressure, fibreoptic view, and complications were compared. RESULTS There were no differences between groups in insertion time or first attempt success (100% vs. 98%). The PLMA required fewer manipulations (3% vs. 15%; P=0.02) to achieve effective ventilation and provided a higher seal pressure (mean [sd] 31 [4] vs. 27 [4] cm H2O; P<0.01). The fibrescopic view of the vocal cords was similar, although easier to achieve with the PLMA. The complication rate was low and similar between the groups. Blood was present on masks in 7% vs. 8% and sore throat in 3% vs. 5% of patients with the PLMA and SLMA, respectively. CONCLUSIONS Airway management in patients anaesthetized in the prone position was efficient with both devices, although the PLMA required fewer manipulations and achieved a higher seal pressure.

Evaluación y manejo de la vía aérea difícil prevista y no prevista: Adopción de guías de práctica

Los algoritmos de manejo de la via aerea dificil (VAD) comprenden un conjunto de estrategias organizadas para facilitar la eleccion de las tecnicas de ventilacion e intubacion con mas probabilidad de exito y menor riesgo de lesion de la via aerea. Las recomendaciones estan basadas en la revision exhaustiva y sistematica de la evidencia disponible y en la opinion de los expertos. La meta es garantizar la oxigenacion del paciente en una situacion de potencial riesgo vital, rapidamente cambiante, que exige una toma de decisiones agil. Su objetivo principal es disminuir el numero y la gravedad de los incidentes criticos asi como las complicaciones que se pueden producir durante el abordaje de la via aerea. Los objetivos secundarios son promover una evaluacion adecuada de la via aerea y el aprendizaje y entrenamiento de las diferentes tecnicas de control de la via aerea. Desde hace unos anos, diversas sociedades nacionales de Anestesiologia (Americana, Francesa, Canadiense, Alemana, Italiana) han editado sus algoritmos de manejo de la via aerea. Tambien se han creado sociedades internacionales especificas para promocionar la practica segura del manejo de la via aerea mediante la investigacion y la educacion, como la SAM (Society for Airway Management, www.sam.zorebo.com), la DAS (Difficult Airway Society, www.das.uk.com) y la EAMS (European Airway Management Society, www.eams.eu.com). De estas, la ASA (American Society of Anesthesiology) y la DAS han publicado recientemente sus algoritmos y muchas instituciones y Servicios de Anestesiologia han hecho sus propias versiones. Esta diversificacion responde a la necesidad de adaptar las estrategias recomendadas a los recursos humanos y materiales de cada entorno, los conocimientos y experiencia personales asi como a las caracteristicas de los pacientes. Aunque no hay estudios que comparen la efectividad de los diferentes algoritmos, los expertos coinciden en que su uso y una correcta planificacion mejoran los resultados del manejo de la via aerea. Sin embargo, la influencia de las guias sobre la practica clinica es dificil de definir, compleja de analizar y variable en el tiempo. Un diseno esmerado, unido a campanas de difusion periodicas, facilitaria su aprendizaje y retencion pudiendo mejorar su efectividad. Algunos algoritmos tienen estructura de arbol e incluye multiples opciones para cada situacion. Este es el caso del algoritmo de la ASA, en los que el listado de tecnicas y dispositivos opcionales aparece en un anexo. Esta disposicion no es facil de recordar, como se refleja en varios estudios realizados tanto entre residentes como especialistas. Por otro lado, el algoritmo de la DAS tiene un diseno de diagrama de flujo con planes secuenciales y un numero limitado de opciones y tecnicas en cada punto. Comprende tres diagramas de control de la VAD no prevista para las situaciones de anestesia electiva, induccion de secuencia rapida y situacion de ventilacion e intubacion imposible, pero no contempla la VAD prevista. El algoritmo de manejo de la VAD que presentamos se proyecto con la intencion de abarcar la valoracion preoperatoria de la via aerea, el desarrollo de diferentes esquemas de control de la VAD, en situaciones que requieren abordajes especificos (situacion de reanimacion y emergencias, ventilacion unipulmonar, pediatria y obstetricia) y el abordaje de la extubacion de este tipo de pacientes. Hasta hoy se han desarrollado los esquemas de actuacion para la evaluacion preoperatoria de la via aerea y el manejo de la situacion de VAD prevista y no prevista. El objetivo de este trabajo es difundir el algoritmo de evaluacion y manejo de la via aerea dificil adoptado por la Societat Catalana d’Anestesiologia, Reanimacio i Terapeutica del Dolor (SCARTD).

Persistence of intracranial diastolic flow in transcranial Doppler sonography exploration of patients in brain death.

OBJECTIVE The persistence of cerebral blood flow (CBF) in patients with whole brain death (BD) diagnosis is an unusual phenomenon. We describe patients with whole BD diagnosed despite persistence of intracranial blood flow on transcranial Doppler sonography (TDS). MATERIALS AND METHODS From January 2001 to December 2002, we reviewed the records of 11 patients. Etiology of BD was craniocephalic trauma in 2 cases, schemic cerebrovascular accident (CVA) in 4 cases, Hemorrhagic CVA in 3 cases, subaracnoid hemorrhage in 1 case, and acute hydrocephalus in 1 case. Six patients had a cerebral decompressive mechanism. In all patients, TDS was used to confirm BD after clinical diagnosis. Additionally, all patients underwent an electroencephalogram (EEG). In 3 patients cerebral angiography (CA) and in 2 others radionuclide angiography (RA) with Tc99m HMPAO were done. RESULTS All TDS studies showed persistent telediastolic positive flow in at least 1 artery. Because the TDS did not confirm the clinical diagnosis of BD, EEG tests were performed showing silence of bioelectrical activity. Those cases showed CA or RA results with a complete absence of CBF. CONCLUSION The TDS technique directly evaluates the intracranial but not the intracerebral circulation. For this reason, during the BD diagnosis for patients with previous decompressive techniques, it was possible to find persistence of intracranial telediastolic flow using TDS. In those cases, it is advisable to use other tests to confirm the clinical diagnosis of BD.