RESUMEN
Continuous optical monitoring of local cerebral microcirculation could benefit neurointensive care patients treated for subarachnoid hemorrhage (SAH). The aim of the study was to evaluate laser Doppler flowmetry (LDF) and diffuse reflectance spectroscopy (DRS) for long-term monitoring of brain microcirculation and oxygen saturation (SO2) in the neurointensive care unit (NICU). A fiber optic probe was designed for intraparenchymal use and connected to LDF and DRS for assessment of the local blood flow (perfusion and tissue reflectance (TLI)) and SO2 in the brain. The optically monitored parameters were compared with conventional NICU monitors and Xe-CT. The LDF signals were low with median and 25 to 75% interquartiles of perfusion = 70 (59 to 83) a.u. and TLI = 2.0 (1.0 to 2.4) a.u. and showed correlation with the NICU monitors in terms of heart rate. Median and interquartiles of SO2 were 17.4 (15.7 to 19.8) %. The lack of correlation between local perfusion and cerebral perfusion pressure indicated intact cerebral autoregulation. The systems were capable of monitoring both local perfusion and SO2 with stable signals in the NICU over 4 days. Further clinical studies are required to evaluate the optical systems' potential for assessing the onset of secondary brain injury.
Asunto(s)
Encéfalo/irrigación sanguínea , Unidades de Cuidados Intensivos , Microcirculación/fisiología , Monitoreo Fisiológico/métodos , Neurología , Óptica y Fotónica/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Humanos , Presión Intracraneal , Flujometría por Láser-Doppler , Perfusión , Tomografía Computarizada por Rayos XRESUMEN
The aim of this study was to adapt and evaluate laser Doppler perfusion monitoring (LDPM) together with custom-designed brain probes and software for continuous recording of cerebral microcirculation in patients undergoing neurosurgery. The LDPM system was used to record perfusion and backscattered light (TLI). These parameters were displayed together with the extracted heart rate (HR), pulsatility index (PI) and signal trends from adjustable time intervals. Technical evaluation was done on skin during thermal provocation. Clinical measurements were performed on ten patients undergoing brain tumour surgery. Data from 76 tissue sites were captured with a length varying between 10 s to 15 min. Statistical comparisons were done using Mann-Whitney tests. Grey and tumour tissue could be separated from white matter using the TLI signal (p < 0.05). The perfusion was significantly higher in grey and tumour tissue compared to white matter (p < 0.005). LDPM was successfully used as an intraoperative tool for monitoring local blood flow and additional parameters linked to cerebral microcirculation (perfusion, TLI, HR and PI) during tumour resection. The systems stability opens up for studies in the postoperative care of patients with, for example, traumatic brain injury or subarachnoid haemorrhage.
Asunto(s)
Circulación Cerebrovascular , Flujometría por Láser-Doppler/instrumentación , Procedimientos Neuroquirúrgicos , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Programas InformáticosRESUMEN
BACKGROUND: Microdialysis has become a routine method for biochemical surveillance of patients in neurosurgical intensive care units. OBJECTIVE: To analyze the intracerebral extracellular levels of 3 interleukins (ILs) during the 7 days after major subarachnoid hemorrhage or traumatic brain injury). METHODS: Microdialysate from 145 severely injured neurosurgical intensive care unit patients (88 with subarachnoid hemorrhage, 57 with traumatic brain injury) was collected every 6 hours for 7 days. The concentrations of IL-1ß and IL-6 were determined by fluorescence multiplex bead technology, and IL-10 was determined by enzyme-linked immunosorbent assay. RESULTS: Presented are the response patterns of 3 ILs during the first week after 2 different types of major brain injury. These patterns are different for each IL and also differ with respect to the kind of pathological impact. For both IL-1ß and IL-6, the initial peaks (mean values for all patients at day 2 being 26.9 ± 4.5 and 4399 ± 848 pg/mL, respectively) were followed by a gradual decline, with IL-6 values remaining 100-fold higher compared with IL-1ß. Female patients showed a stronger and more sustained response. The response of IL-10 was different, with mean values less than 23 pg/mL and with no significant variation between any of the postimpact days. For all 3 ILs, the responses were stronger in subarachnoid hemorrhage patients. The study also indicates that under normal conditions, IL-1ß, IL-6, and IL-10 are present only at very low concentrations or not at all in the extracellular space of the human brain. CONCLUSION: This is the first report presenting in some detail the human cerebral response of IL-1ß, IL-6, and IL-10 after subarachnoid hemorrhage and traumatic brain injury. The 3 ILs have different reaction patterns, with the response of IL-1ß and IL-6 being related to the type of cerebral damage sustained, whereas the IL-10 response was less varied.
Asunto(s)
Lesiones Encefálicas/metabolismo , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Hemorragia Subaracnoidea/metabolismo , Química Encefálica/inmunología , Lesiones Encefálicas/inmunología , Ensayo de Inmunoadsorción Enzimática , Líquido Extracelular , Femenino , Humanos , Interleucina-10/análisis , Interleucina-1beta/análisis , Interleucina-6/análisis , Masculino , Microdiálisis/métodos , Hemorragia Subaracnoidea/inmunologíaRESUMEN
OBJECTIVE: The extracellular levels of eight different inflammatory agents were analyzed during the initial 36 hours after insertion of microdialysis catheters in patients. METHODS: Cerebral extracellular fluid from 38 patients who were treated in a neurosurgical intensive care unit for severe brain injury was collected every 6 hours for 36 hours. The concentration of interleukin (IL)-1 beta, IL-6, IL-8, macrophage inflammatory protein-1 beta, regulated on activation, normal T-cell expressed and secreted (RANTES), fibroblast growth factor-2, and vascular endothelial growth factor was determined by a multiplex assay, and IL-10 was determined by enzyme-linked immunosorbent assay. RESULTS: This is the first report regarding the presence of IL-10, IL-8, macrophage inflammatory protein-1 beta, regulated on activation, T-cell expressed and secreted, vascular endothelial growth factor, and fibroblast growth factor-2 in the tissue level proper of the living human brain. The study also provides new information regarding the response of IL-1 beta and IL-6 after insertion of a microdialysis catheter. The study confirms that the intriguing patterns of interplay between different components of the inflammatory response studied in laboratory settings are present in the human brain. This was most clearly observed in the variations in response between the three different chemokines investigated, as well as in the rapid and transient response of fibroblast growth factor-2. CONCLUSION: The data presented illustrate the opportunity to monitor biochemical events of possible importance in the human brain and indicate the potential of such monitoring in neurosurgical intensive care. The study also underlines that any analysis of events in the brain involving mechanical invasiveness needs to take into account biochemical changes that are directly related to the manipulation of brain tissue.
Asunto(s)
Citocinas/metabolismo , Líquido Extracelular/metabolismo , Factores de Crecimiento Nervioso/metabolismo , Neurocirugia , Complicaciones Posoperatorias/inmunología , Complicaciones Posoperatorias/metabolismo , Lesiones Encefálicas/cirugía , Electroquímica/métodos , Femenino , Humanos , Masculino , Microdiálisis/métodos , Neurocirugia/métodos , Factores de TiempoRESUMEN
OBJECT: The aim of this study was to make a preliminary evaluation of whether microdialysis monitoring of cytokines and other proteins in severely diseased neurosurgical patients has the potential of adding significant information to optimize care, thus broadening the understanding of the function of these molecules in brain injury. METHODS: Paired intracerebral microdialysis catheters with high-cutoff membranes were inserted in 14 comatose patients who had been treated in a neurosurgical intensive care unit following subarachnoidal hemorrhage or traumatic brain injury. Samples were collected every 6 hours (for up to 7 days) and were analyzed at bedside for routine metabolites and later in the laboratory for interleukin (IL)-l and IL-6; in two patients, vascular endothelial growth factor and cathepsin-D were also checked. Aggregated microprobe data gave rough estimations of profound focal cytokine responses related to morphological tissue injury and to anaerobic metabolism that were not evident from the concomitantly collected cerebrospinal fluid data. Data regarding tissue with no macroscopic evidence of injury demonstrated that IL release not only is elicited in severely compromised tissue but also may be a general phenomenon in brains subjected to stress. Macroscopic tissue injury was strongly linked to IL-6 but not IL- lb activation. Furthermore, IL release seems to be stimulated by local ischemia. The basal tissue concentration level of IL-lb was estimated in the range of 10 to 150 pg/ml; for IL-6, the corresponding figure was 1000 to 20,000 pg/ml. CONCLUSIONS: Data in the present study indicate that catheters with high-cutoff membranes have the potential of expanding microdialysis to the study of protein chemistry as a routine bedside method in neurointensive care.
Asunto(s)
Conmoción Encefálica/diagnóstico , Lesiones Encefálicas/diagnóstico , Cuidados Críticos , Hematoma Subdural/diagnóstico , Interleucina-1beta/líquido cefalorraquídeo , Interleucina-6/líquido cefalorraquídeo , Microdiálisis/instrumentación , Monitoreo Fisiológico/instrumentación , Complicaciones Posoperatorias/diagnóstico , Hemorragia Subaracnoidea/diagnóstico , Encéfalo/inmunología , Conmoción Encefálica/inmunología , Conmoción Encefálica/cirugía , Lesiones Encefálicas/inmunología , Lesiones Encefálicas/cirugía , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/inmunología , Catepsina D/líquido cefalorraquídeo , Ensayo de Inmunoadsorción Enzimática , Ácido Glutámico/líquido cefalorraquídeo , Glicerol/líquido cefalorraquídeo , Hematoma Subdural/inmunología , Hematoma Subdural/cirugía , Complicaciones Posoperatorias/inmunología , Pronóstico , Valores de Referencia , Análisis de Regresión , Hemorragia Subaracnoidea/inmunología , Hemorragia Subaracnoidea/cirugía , Factor A de Crecimiento Endotelial Vascular/líquido cefalorraquídeoRESUMEN
OBJECTIVE: To evaluate a new intracerebral microdialysis catheter with a high-cutoff membrane and its potential for the study of macromolecules in the human brain. METHODS: Paired intracerebral microdialysis catheters were inserted in 10 patients who became comatose after subarachnoid hemorrhage or traumatic brain injury and were then treated in our neurosurgical unit. The only differences from the routine use of microdialysis in our clinic were the length (20 mm) and cutoff properties of the catheter membranes (100 kD) and the perfusion fluids used (standard perfusion fluid, 3.5% albumin, or Ringer-dextran 60). Samples were weighed (for net fluid fluxes) and analyzed at bedside (for routine metabolites) and later in the laboratory (for total protein and interleukin-6). The in vitro recovery of glucose, glutamate, and glycerol were also investigated under different conditions. RESULTS: Even brief perfusion with standard perfusion fluid resulted in a significant loss of volume from the microdialysis system. For albumin and Ringer-dextran 60 fluid, recovery was comparable to standard settings. Interleukin-6 (highest value close to 25,000 pg/ml) was sampled from all catheters, and total protein was analyzed from catheters perfused with Ringer-dextran 60 (average concentration, 234 mug protein/ml). There were detectable patterns of variations in the concentration of interleukin-6, seemingly related to concomitant variations in intracerebral conditions. In the present study, no direct comparison was made with the standard CMA 70 catheter (CMA Microdialysis, Stockholm, Sweden), but in vivo, the measured mean concentrations of glucose, glycerol, lactate, and pyruvate were comparable to those previously reported from standard catheters. In vitro, the recovery of metabolites was better when using Ringer-dextran 60 compared with albumin. CONCLUSION: Microdialysis catheters with high-cutoff membranes can be used in routine clinical practice, allowing for sampling and analysis of cytokines and other macromolecules.