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A self-excited oscillating pulsed abrasive water jet polishing method is proposed to solve the problems of low removal efficiency in traditional abrasive water jet polishing and the influence of an external flow field on the material surface removal rate. The self-excited oscillating chamber of the nozzle was used to generate pulsed water jets to reduce the impact of the jet stagnation zone on material surface removal and increase the jet speed to improve processing efficiency. ANSYS Fluent was employed to simulate the processing flow field characteristics for different lengths of oscillation cavities. The simulation results indicate that the velocity of the jet shaft reached a maximum of 178.26 m/s when the length of the oscillation cavity was 4 mm. The erosion rate of the material is linear with the processing angle. A nozzle with a length of 4 mm of the self-excited oscillating cavity was fabricated for SiC surface polishing experiments. The results were compared with those of ordinary abrasive water jet polishing. The experimental results showed that the self-excited oscillation pulse fluid enhanced the erosion ability of the abrasive water jet on the SiC surface and significantly improved the material-removal depth of the abrasive water jet polishing SiC. The maximum surface erosion depth can be increased by 26 µm.
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Electrospinning is a low-cost and straightforward method for producing various types of polymers in micro/nanofiber form. Among the various types of polymers, electrospun piezoelectric polymers have many potential applications. In this study, a new type of functional microfiber composed of poly(γ-benzyl-α,L-glutamate) (PBLG) and poly(vinylidene fluoride) (PVDF) with significantly enhanced electromechanical properties has been reported. Recently reported electrospun PBLG fibers exhibit polarity along the axial direction, while electrospun PVDF fibers have the highest net dipole moment in the transverse direction. Hence, a combination of PBLG and PVDF as a core-shell structure has been investigated in the present work. On polarization under a high voltage, enhancement in the net dipole moment in each material and the intramolecular conformation was observed. The piezoelectric coefficient of the electrospun PBLG/PVDF core-shell fibers was measured to be up to 68 pC N-1 (d33), and the voltage generation under longitudinal extension was 400 mVpp (peak-to-peak) at a frequency of 60 Hz, which is better than that of the electrospun homopolymer fibers. Such new types of functional materials can be used in various applications, such as sensors, actuators, smart materials, implantable biosensors, biomedical engineering devices, and energy harvesting devices.
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INTRODUCTION: Standardized protocols are provided for maintenance and replacement fluid therapy in critically ill patients. However, unintended fluid sources (analgesics, antibiotics and other drugs) are not always taken into account when prescribing intravenous fluid therapy. We evaluated the extent to which maintenance, resuscitation and unintended fluids contributed to total fluid load in elective coronary artery bypass graft patients during their ICU stay. METHODS: Data on intravenous and oral fluid input and output were retrospectively collected from the electronic medical files. RESULTS: Sixty patients were included. Maintenance fluids represented 1435 ± 570mL (49%) and 2214 ± 657mL (71%), resuscitation fluids 847 ± 542mL (29%) and 338 ± 559mL (11%), unintended fluids 639 ± 162mL (22%) and 576 ± 285mL (18%) respectively on day 1 and day 2. Mean oral intake increased almost fourfold (from 258mL to 1017mL) on the second day. CONCLUSION: Postoperative maintenance and resuscitation fluids are responsible for most of the observed total fluid load on the first two days after elective coronary artery bypass graft surgery. Unintended fluid load is underestimated and has to be taken into account during fluid prescription.
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Puente de Arteria Coronaria , Fluidoterapia/métodos , Resucitación/métodos , Anciano , Enfermedad Crítica/terapia , Procedimientos Quirúrgicos Electivos , Femenino , Humanos , Infusiones Intravenosas , Masculino , Proyectos Piloto , Cuidados Posoperatorios/métodos , Estudios RetrospectivosRESUMEN
The pathogenesis of delirium in critically ill patients is multifactorial. How hypotension and hypoxemia affect brain function and whether they can promote delirium remains unclear. A high cumulative positive fluid balance may also have a negative effect on brain function and promote delirium. We hypothesized that delirium would be more likely to develop in patients with low systemic arterial pressure, hypoxemia and a higher positive fluid balance, and investigated these associations in a prospective observational cohort study in patients with shock. After initial resuscitation, episodes of hypotension, defined as a mean arterial pressure (MAP) <65 mmHg or diastolic pressure <60 mmHg, and hypoxemia, defined as peripheral oxygen saturation (SpO2) <90% for more than one minute or any arterial oxygen concentration (PaO2) <90 mmHg, were recorded during the first 5 days of the ICU stay. Fluid balance was evaluated daily and the 5-day cumulative fluid balance recorded. Delirium was assessed using the Confusion Assessment Method for the ICU. A total of 252 patients were admitted with shock during the study period; 185 (73%) developed delirium. Patients who developed delirium also had more episodes of hypotension with a low MAP (p = 0.013) or diastolic pressure (p = 0.018) during the first five days of the ICU stay than those who did not. Patients with a higher cumulative fluid balance during the same period were also more likely to develop delirium (p = 0.01); there was no significant difference in the occurrence of hypoxemia between groups. Joint modeling, combining a linear-mixed model and an adjusted Cox survival model showed that low diastolic pressure (alpha effect = -0.058±0.0013, p = 0.043) and a positive cumulative fluid balance (alpha effect = 0.04±0.003, p = 0.021) were independently associated with delirium. In conclusion, low diastolic pressure and a cumulative positive fluid balance but not hypoxemia were independently associated with development of delirium in patients with shock.
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Delirio/diagnóstico , Hipotensión/complicaciones , Monitoreo Fisiológico , Choque/complicaciones , Equilibrio Hidroelectrolítico , Anciano , Delirio/etiología , Femenino , Humanos , Hipotensión/fisiopatología , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Choque/fisiopatologíaRESUMEN
PURPOSES: We investigated whether high prolactin levels were associated with delirium in septic patients because neuropsychiatric disorders are frequently associated with hyperprolactinemia. MATERIALS AND METHODS: Prolactin levels were measured daily for 4 days in 101 patients with sepsis. Delirium was assessed using the Richmond Agitation Sedation Scale and the Confusion Assessment Method in the ICU. RESULTS: Delirium developed in 79 patients (78%) and was more common in patients older than 65 years. Prolactin levels were higher in patients with delirium than in those without over the 4 days of observation (P = .032). In patients with delirium, higher prolactin levels were associated with a lower incidence of nosocomial infection (P = .006). Multivariable logistic regression showed that the Sequential Organ Failure Assessment score at intensive care unit admission (odds ratio, 1.24; 95% confidence interval, 1.04-1.48; P = .002) and the combined effect of prolactin levels with age (odds ratio, 1.018; 95% confidence interval, 1.01-1.031; P = .006) were associated with the development of delirium. CONCLUSIONS: High prolactin levels may be a risk factor for delirium in septic patients.
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Biomarcadores/sangre , Delirio/etiología , Hiperprolactinemia/diagnóstico , Prolactina/sangre , Sepsis , APACHE , Factores de Edad , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Cuidados Críticos , Infección Hospitalaria , Delirio/sangre , Femenino , Humanos , Hiperprolactinemia/sangre , Hiperprolactinemia/complicaciones , Unidades de Cuidados Intensivos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Estudios Prospectivos , Psicometría , Agitación Psicomotora/sangre , Agitación Psicomotora/etiología , Factores de RiesgoRESUMEN
OBJECTIVES: To investigate cortisol levels in brain dysfunction in patients with severe sepsis and septic shock. METHODS: In 128 septic and sedated patients, we studied brain dysfunction including delirium and coma by the evaluation of Richmond Agitation Sedation Scale (RASS), the Confusion Method Assessment in the ICU (CAM-ICU) after sedation withdrawal and the measurement of serum S100B biomarker of brain injury. Serum cortisol and S100B were measured within 12 hours after ICU admission and daily over the next four days. RESULTS: Brain dysfunction was observed in 50% (64/128) before but in 84% (107/128) of patients after sedation withdrawal, and was more common in the patients older than 57 years (P = 0.009). Both cortisol (P = 0.007) and S100B levels (P = 0.028) were higher in patients with than patients without brain dysfunction. Cortisol levels were associated with ICU mortality (hazard ratio = 1.17, P = 0.024). Multivariate logistic regression showed that cortisol (odds ratio (OR): 2.34, 95% CI (2.01, 3.22), P = 0.02) and the combination effect of cortisol with age (OR: 1.004, 95% CI (1.002, 1.93), P = 0.038) but not S100B were associated with brain dysfunction. CONCLUSIONS: Cortisol was an associated-risk factor of brain dysfunction in patients with severe sepsis and septic shock.
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Sedación Consciente , Hidrocortisona/metabolismo , Sepsis/sangre , Choque Séptico/sangre , Anciano , Lesiones Encefálicas/sangre , Lesiones Encefálicas/complicaciones , Lesiones Encefálicas/patología , Coma/sangre , Coma/complicaciones , Coma/patología , Delirio/sangre , Delirio/complicaciones , Delirio/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Subunidad beta de la Proteína de Unión al Calcio S100/sangre , Sepsis/complicaciones , Sepsis/patología , Choque Séptico/complicaciones , Choque Séptico/patologíaRESUMEN
BACKGROUND: Few studies have investigated high-frequency percussive ventilation (HFPV) in adult patients with acute respiratory distress syndrome (ARDS). MATERIALS AND METHODS: We retrospectively analyzed data from critically ill-patients with moderate and severe ARDS who received HFPV. Ventilation and oxygenation were governed according to a predefined protocol. HFPV was continued until patients could be switched to conventional ventilation. RESULTS: A total of 42 patients (20 with pneumonia-related ARDS and 22 non-septic ARDS cases) were evaluable. Baseline demographic characteristics, severity of illness, lung injury score; pH and respiratory variables were comparable between pneumonia and non-sepsis-related ARDS. Within 24 h, HFPV restored normal pH and PaCO2 and considerably improved oxygenation. Oxygenation improved more in non-septic than in pneumonia-related ARDS. Patients with pneumonia-induced ARDS also remained longer HFPV-dependent (7.0 vs. 4.9 days; P < 0.05). Mortality at 30 days was significantly higher in pneumonia-related than in non-sepsis-related ARDS (50% vs. 18%; P = 0.01). CONCLUSIONS: HFPV caused rapid and sustained improvement of oxygenation and ventilation in patients with moderate to severe ARDS. Less improved oxygenation, longer ventilator dependency and worse survival were observed in pneumonia-related ARDS.
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BACKGROUND: To investigate if serum S100B protein levels could early detect cerebral complications under treatment extracorporeal membrane oxygenation (ECMO). METHODS: Serum S100B levels were measured over 5 days in 32 patients with cardiogenic and septic shock, including 15 patients who treated by ECMO and 17 who did not. Cerebral complications included hemorrhage, stroke, encephalopathy with myoclonus, and brain death. Delirium was identified by the positive Confusion Assessment Method in the ICU. RESULTS: S100B levels were elevated in 24/32 patients (75 %) at ICU admission. Five patients developed cerebral complications (2 hemorrhages with 1 brain death, 1 encephalopathy with myoclonus in the ECMO group and 2 strokes in the non-ECMO group). At day 5, S100B levels were higher in the 5 patients with cerebral complications than in the 27 without cerebral complications, regardless of ECMO (0.426 [0.421, 0.652] vs. 0.102 [0.085, 0.135] µg/L, p = 0.011). S100B levels were also more elevated in 3 patients with than in 12 without cerebral complications associated with ECMO (0.799 [0.325, 0.965] vs. 0.102 [0.09, 0.607] µg/L, p = 0.033). S100B levels were not associated with delirium after sedation withdrawal. CONCLUSIONS: Measurement serum S100B could be useful to detect cerebral complications in deeply sedated patients associated with ECMO but not for monitoring delirium after sedation withdrawal.
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APACHE , Encefalopatías/diagnóstico , Encefalopatías/etiología , Oxigenación por Membrana Extracorpórea/efectos adversos , Subunidad beta de la Proteína de Unión al Calcio S100/sangre , Choque Cardiogénico/terapia , Anciano , Muerte Encefálica/diagnóstico , Encefalopatías/mortalidad , Delirio/diagnóstico , Delirio/etiología , Delirio/mortalidad , Oxigenación por Membrana Extracorpórea/métodos , Oxigenación por Membrana Extracorpórea/mortalidad , Femenino , Humanos , Hemorragias Intracraneales/diagnóstico , Hemorragias Intracraneales/etiología , Hemorragias Intracraneales/mortalidad , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Mioclonía/diagnóstico , Mioclonía/etiología , Mioclonía/mortalidad , Estudios Prospectivos , Choque Cardiogénico/mortalidad , Choque Séptico/mortalidad , Choque Séptico/terapia , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/etiología , Accidente Cerebrovascular/mortalidadRESUMEN
INTRODUCTION: Sepsis-associated encephalopathy (SAE) is a diffuse cerebral dysfunction induced by the immuno-inflammatory response to infection. Elevated levels of the brain-specific S100B protein are present in many septic patients and reflect the severity of SAE. Adjunctive treatment with drotrecogin alfa (activated) (DrotAA), the human recombinant form of activated protein C, has been shown to improve mortality in patients with severe sepsis-induced organ failure. We studied the effect of DrotAA on S100B levels in patients with acute septic shock who presented with increased baseline values of this biomarker. METHODS: All patients received standard goal-directed resuscitation treatment. Patients with pre-existing or acute neurological disorders were excluded. Based on the Glasgow coma scale (GCS), patients were classified into two groups: GCS >or= 13 and GCS <13. DrotAA was given as a continuous infusion of 24 microg/kg/h for 96 h. S100B was measured before sedation and the start of DrotAA (0 h) and at 32 h, 64 h and 96 h and at corresponding time points in patients not treated with DrotAA. The lower limit of normal was < 0.5 microg/L. RESULTS: Fifty-four patients completed the study. S100B was increased in 29 (54%) patients. Twenty-four patients (9 with GCS >or= 13 and 15 with GCS <13) received DrotAA. S100B levels in DrotAA-treated patients with a GCS <13, though higher at baseline than in untreated subjects (1.21 +/- 0.22 microg/L vs. 0.95 +/- 0.12 microg/L; P = 0.07), progressively and significantly decreased during infusion (0.96 +/- 0.22 microg/L at 32 h, P = 0.3; 0.73 +/- 0.12 microg/L at 64 h, P < 0.05; and 0.70 +/- 0.13 microg/L at 96 h, P < 0.05 vs. baseline). This patient group had also significantly lower S100B values at 64 h and at 96 h than their untreated counterparts. In the patients with a GCS >or= 13, S100B levels were not influenced by DrotAA treatment. CONCLUSIONS: S100B-positivity is present in more than half of the patients with septic shock. When increased S100B levels are used as a surrogate for SAE, adjunctive DrotAA treatment seems to beneficially affect the evolution of severe SAE as discriminated by an admission GCS <13.
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Antiinfecciosos/farmacología , Encefalopatías/prevención & control , Proteína C/farmacología , Choque Séptico/tratamiento farmacológico , Anciano , Anciano de 80 o más Años , Antiinfecciosos/uso terapéutico , Bélgica , Encefalopatías/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proteína C/uso terapéutico , Proteínas Recombinantes/farmacología , Proteínas Recombinantes/uso terapéutico , Choque Séptico/complicacionesRESUMEN
OBJECTIVE: We investigated whether serum levels of neuron-specific enolase (NSE) and S-100beta protein could be used to evaluate cerebral injury and to predict outcome in severe sepsis and severe septic shock. DESIGN: Prospective study. SETTING: University hospital. PATIENTS AND MEASUREMENTS: In 170 consecutively enrolled patients with severe sepsis and septic shock, serum S-100beta and NSE were measured daily during four consecutive days after intensive care unit admission. Admission Glasgow Coma Scale before sedation and daily Sequential Organ Failure Assessment scores were recorded in all patients. Acute encephalopathy was defined as either a state of agitation, confusion, irritability, and convulsions (type A) or characterized by somnolence, stupor, and coma (type B) and persistently observed during 72 hrs after withdrawing sedation. When clinically indicated, contrast computed tomography or magnetic resonance imaging were performed to evaluate brain injury. MAIN RESULTS: S-100beta and NSE increased in, respectively, 72 (42%) and 90 (53%) patients. High biomarker levels were associated with the maximum Sequential Organ Failure Assessment scores (p = .001), and the highest values were found in patients who died early, within 4 days of inclusion (p = .005). Low consciousness encephalopathy type B was more frequently observed in patients with elevated S-100beta (p = .004). S-100beta levels of >or=4 microg/L were associated with severe brain ischemia or hemorrhage, and values of <2 microg/L were found in patients with diffuse cerebral embolic infarction lesions. High S-100beta levels were associated with higher intensive care unit mortality (p = .04) and represented the strongest independent predictor of intensive care unit survival, whereas NSE and the Glasgow Coma Scale failed to predict fatal outcome. CONCLUSIONS: S-100beta and NSE are frequently increased and associated with brain injury in patients with severe sepsis and septic shock. S-100beta levels more closely reflected severe encephalopathy and type of brain lesions than NSE and the Glasgow Coma Scale.
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Biomarcadores/sangre , Encefalopatías/sangre , Factores de Crecimiento Nervioso/sangre , Fosfopiruvato Hidratasa/sangre , Proteínas S100/sangre , Sepsis/complicaciones , Choque Séptico/complicaciones , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Encefalopatías/diagnóstico , Encefalopatías/etiología , Coma/diagnóstico , Femenino , Escala de Coma de Glasgow , Humanos , Unidades de Cuidados Intensivos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Subunidad beta de la Proteína de Unión al Calcio S100 , Tomografía Computarizada por Rayos XRESUMEN
We challenged the current management of uncontrolled haemorrhagic shock (UHS) and put forward a hypothesis that therapeutic mild hypothermia combined with delayed fluid resuscitation will improve the survival rate. After an initial blood withdrawal of 3 ml/100g for 15 min, the rat's tail was amputated up to 75% to induce UHS phase I. The mean arterial blood pressure (MAP) was maintained at 40 mmHg or 80 mmHg, according to the assigned study group. This was followed by homeostasis of the tail wound and increase of the MAP up to 100 mmHg during resuscitation phase II. Finally, phase III was an observation of phase up to 72 h. Rats were anaesthetised and randomised into four groups. Group 1 received immediate fluid resuscitation and normothermia. Group 2 received immediate fluid resuscitation and therapeutic mild hypothermia. Group 3 received limited fluid solutions to maintain MAP at 40 mmHg and normothermia. Group 4 also received limited fluid solution, but the rats were subjected to therapeutic mild hypothermia. In groups 2 and 4, the body temperature was kept at 34 degrees C throughout the UHS phase I and resuscitation phase II. At the end of the observation phase III, the brains of the animals were fixed and analysed histologically. The blood loss from the tail during the UHS phase I was significantly higher in groups 1 and 2. The survival rate was 33.3, 83.3, 58.3 and 91.7%, respectively in groups 1-4. In all surviving rats, no histological brain damage was observed. These results indicate that therapeutic mild hypothermia or delayed fluid resuscitation increase the survival rate in this model. However, when mild hypothermia and limited fluid resuscitation were combined, the survival rate was the highest.
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Fluidoterapia/métodos , Hipotermia Inducida/métodos , Resucitación/métodos , Choque Hemorrágico/mortalidad , Choque Hemorrágico/terapia , Análisis de Varianza , Animales , Transfusión Sanguínea/métodos , Terapia Combinada , Modelos Animales de Enfermedad , Masculino , Probabilidad , Distribución Aleatoria , Ratas , Ratas Wistar , Respiración Artificial/métodos , Sensibilidad y Especificidad , Índice de Severidad de la Enfermedad , Tasa de SupervivenciaRESUMEN
OBJECTIVE: To test the hypothesis that resuscitative mild hypothermia (MH) (34 degrees C) or breathing fractional inspired oxygen (FIo2) of 1.0 would prolong survival time during lethal uncontrolled haemorrhagic shock (UHS) in mechanically ventilated rats. METHODS: Forty Wistar rats were anaesthetized with halothane, nitrous oxide and oxygen (70/30%), intubated and mechanically ventilated. UHS was induced by volume-controlled blood withdrawal of 3 ml/100 g over 15 min, followed by 75% tail amputation of its length. The animals were randomly divided into four UHS treatment groups (10 rats in each group): group 1 was maintained on an FIo2 of 0.21 and rectal temperature of 37.5 degrees C. Group 2 was maintained on an FIo2 of 0.21 and induced MH. Group 3 was maintained on an FIo2 of 1.0 and 37.5 degrees C. Group 4 was maintained on an FIo2 of 1.0 and MH. Rats were observed otherwise untreated until death. RESULTS: During the initial blood withdrawal, mean arterial pressure (MAP) decreased to 40 mmHg, and the heart rate (HR) increased up to 400 beats/min. The induction of MH increased MAP to 60 mmHg and increased survival time. Moreover, it reduced the HR to 300 beats/min but did not increase bleeding. Ventilation with an FIo2 of 1.0 did not influence MAP, blood loss or survival time, but increased arterial oxygen tension. The mean survival time was 62, 202, 68 and 209 min in groups 1, 2, 3 and 4, respectively. Blood loss from the tail was 1.0, 1.2, 0.9 and 0.7 ml, respectively, in groups 1, 2, 3 and 4. CONCLUSION: MH prolonged the survival time during UHS in mechanically ventilated rats. However, an FIo2 of 1.0 did not influence the survival time or blood loss from the tail.
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Hipotermia Inducida , Terapia por Inhalación de Oxígeno , Oxígeno/metabolismo , Respiración Artificial , Resucitación/métodos , Choque Hemorrágico/terapia , Animales , Intubación Intratraqueal , Modelos Animales , Ratas , Ratas Wistar , Choque Hemorrágico/fisiopatología , Análisis de Supervivencia , Factores de TiempoRESUMEN
After induction of cecal perforation, 20 anesthetized sheep were randomized to be treated, when arterial blood pressure fell below 75 mm Hg, with vasopressin (fixed dose of 0.02 U/minute), norepinephrine (0.5-5 microg/kg/minute titrated to maintain mean arterial pressure between 75 and 85 mm Hg), vasopressin + norepinephrine (vasopressin at fixed dose 0.01 U/minute plus norepinephrine titrated as for norepinephrine only group), or no vasopressor (Ringer's lactate [control]). Mean arterial pressure was well maintained in all treatment groups. Superior mesenteric arterial blood flow was significantly lower in the vasopressin + norepinephrine group than in the vasopressin group. Vasopressin alone or combined with norepinephrine limited the increase in blood lactate concentration and ileal PCO2-gap compared with control and norepinephrine groups. Urine output was higher in the vasopressin group than in control and norepinephrine groups. Survival time was longer in the vasopressin (30 +/- 6 hours) and vasopressin + norepinephrine (30 +/- 3 hours) groups than in the norepinephrine group (20 +/- 1 hours, p < 0.05) and in all treatment groups than in the control group (17 +/- 2 hours, p < 0.05). Tissue injury was less severe in the vasopressin and vasopressin + norepinephrine groups than in the others. In this clinically relevant model of septic shock due to peritonitis, vasopressin administration (alone or with norepinephrine) can prolong survival.