Long hydraulic retention time mediates stable volatile fatty acids production against slight pH oscillations.

The effect of operational conditions on the stability of acidogenic fermentation (AF) devoted to volatile fatty acids (VFAs) production still presents numerous gaps to achieve high yields and fully understand the responses of open microbiomes associated to this technology. To cope with that, this investigation was designed to assess the stability of VFAs production via AF of agro-food wastes at high hydraulic retention times (HRTs) (20 and 30 d) and pH oscillations (5.8-6.2). Similar bioconversion efficiencies (∼50 %) were reached regardless of the HRT, revealing that HRT of 20 d can be considered as a threshold from which, no further improvement was achieved. The combination of long HRTs, 25 °C and acid pHs promoted a robust microbiome that resulted in a stable outcome against pH variations, being Clostridiales order identified as key player of AF stability. These conditions mediated a high selectivity in the VFAs production profile, with acetic and butyric acids, prevailing in the VFAs pool (∼80 % of total VFAs) at HRT 20 d. The selection of appropriated conditions was shown to be critical to maximize the hydrolysis and acidogenesis of the substrate and attain a stable effluent against pH oscillations.

Microbial lipids from organic wastes: Outlook and challenges.

Microbial lipids have recently drawn a lot of attention as renewable sources for biochemicals production. Strong research efforts have been addressed to efficiently use organic wastes as carbon source for microbial lipids, which would definitively increase the profitability of the production process and boost a bio-based economy. This review compiles interesting traits of oleaginous microorganisms and highlights current trends on microbial- and process-oriented approaches to maximize microbial oil production from inexpensive substrates like lignocellulosic sugars, volatile fatty acids and glycerol. Furthermore, downstream processes such as cell harvesting or lipid extraction, that are decisive for the cost-effectiveness of the process, are discussed. To underpin microbial oils within the so demanded circular economy, associated challenges, recent advances and possible industrial applications that are also identified in this review.

Nanopolystyrene beads affect motility and reproductive success of oyster spermatozoa (Crassostrea gigas).

Oysters are keystone species that use external fertilization as a sexual mode. The gametes are planktonic and face a wide range of stressors, including plastic litter. Nanoplastics are of increasing concern because their size allows pronounced interactions with biological membranes, making them a potential hazard to marine life. In the present study, oyster spermatozoa were exposed for 1 h to various doses (from 0.1 to 25 µg mL-1) of 50-nm polystyrene beads with amine (50-NH2 beads) or carboxyl (50-COOH beads) functions. Microscopy revealed adhesion of particles to the spermatozoa membranes, but no translocation of either particle type into cells. Nevertheless, the 50-NH2 beads at 10 µg mL-1 induced a high spermiotoxicity, characterized by a decrease in the percentage of motile spermatozoa (-79%) and in the velocity (-62%) compared to control spermatozoa, with an overall drop in embryogenesis success (-59%). This major reproduction failure could be linked to a homeostasis disruption in exposed spermatozoa. The 50-COOH beads hampered spermatozoa motility only when administered at 25 µg mL-1 and caused a decrease in the percentage of motile spermatozoa (-66%) and in the velocity (-38%), but did not affect embryogenesis success. Microscopy analyses indicated these effects were probably due to physical blockages by microscale aggregates formed by the 50-COOH beads in seawater. This toxicological study emphasizes that oyster spermatozoa are a useful and sensitive model for (i) deciphering the fine interactions underpinning nanoplastic toxicity and (ii) evaluating adverse effects of plastic nanoparticles on marine biota while waiting for their concentration to be known in the environment.

[Unplanned extubation in ICU, and the relevance of non-dependent patient variables the quality of care]. / Extubación no programada en UCI y variables no dependientes del enfermo para mejorar la calidad.

OBJECTIVE: To evaluate, for a consecutive year, the magnitude of unplanned extubation, looking for non-dependent patient variables. MATERIAL AND METHODS: Prospective, observational study of cases and controls in a mixed intensive care unit within in a tertiary hospital. Patients were considered cases with more than 24 hours who had an episode of unplanned extubation. Prospective collection of variables case as time of unplanned extubation (collection time), identification of the box where the patient was admitted, presence and type of physical restraint, development of ventilator-associated pneumonia (VAP) and death. RESULTS: There were 17 unplanned extubation in 15 patients, 1.21 unplanned extubation per 100 days of MV. The unplanned extubation had an inhomogeneous spatial distribution (number of boxes). The time distribution of cases compared with controls showed significant differences in time distribution (P=.02). The comparative analysis between cases and controls, showed increased mortality, increased length of ICU stay, longer hospital stay and increased risk for VAP when patients suffer an episode of unplanned extubation. DISCUSSION: Unplanned extubation occurs most frequently in a given time slot of the day, may play a role in the spatial location of the patient; occurs most often in patients who are in the process of weaning from mechanical ventilation, and develop greater VAP.

Effect of organic loading rate on anaerobic digestion of thermally pretreated Scenedesmus sp. biomass.

Biogas production is one of the means to produce a biofuel from microalgae. Biomass consisting mainly of Scenedesmus sp. was thermally pretreated and optimum pretreatment length (1 h) and temperature (90 °C) was selected. Different chemical composition among batches stored at 4 °C for different lengths of time resulted in organic matter hydrolysis percentages ranging from 3% to 7%. The lower percentages were attributed to cell wall thickening observed during storage for 45 days. The different hydrolysis percentages did not cause differences in anaerobic digestion. Pretreatment of Scenedesmus sp. at 90 °C for 1h increased methane production 2.9 and 3.4-fold at organic loading rates (OLR) of 1 and 2.5 kg COD m(-3) day(-1), respectively. Regardless the OLR, inhibition caused by organic overloading or ammonia toxicity were not detected. Despite enhanced methane production, anaerobic biodegradability of this biomass remained low (32%). Therefore, this microalga is not a suitable feedstock for biogas production unless a more suitable pretreatment can be found.

Comparison of ultrasound and thermal pretreatment of Scenedesmus biomass on methane production.

Ultrasound at 20Hz was applied at different energy levels (Es) to treat Scenedesmus biomass, and organic matter solubilization, particle size distribution, cell disruption and biochemical methane potential were evaluated. An Es of 35.5 and 47.2MJ/kg resulted in floc deagglomeration but no improvement in methane production compared to untreated biomass. At an Es of 128.9, cell wall disruption was observed together with a 3.1-fold organic matter solubilization and an approximately 2-fold methane production in comparison with untreated biomass. Thermal pretreatment at 80°C caused cell wall disruption and improved anaerobic biodegradability 1.6-fold compared to untreated biomass. Since sonication caused a temperature increase in samples to as high as 85°C, it is likely that thermal effects accounted for much of the observed changes in the biomass. Given that ultrasound treatment at the highest Es studied only increased methane production by 1.2-fold over thermal treatment at 80°C, the higher energy requirement of sonication might not justify the use of this approach over thermal treatment.

[Utility of the dead space fraction (Vd/Vt) as a predictor of extubation success]. / Valor de la fracción de espacio muerto (Vd/Vt) como predictor de éxito en la extubación.

PURPOSE: To determine the value of Vd/Vt as a predictor of extubation failure in patients with mechanical ventilation admitted to the intensive care units. DESIGN: A prospective, observational cohort study conducted from 1 September 2010 to 1 March 2011. SETTING: General intensive care unit (G-ICU) of a third level university hospital. PATIENTS OR PARTICIPANTS: The study included patients on mechanical ventilation (MV) for over 12 hours, and who in the process of weaning were subjected to low-level pressure support. Exclusion criteria were age under 18 years, ventilation via tracheotomy and patients failing to cooperate for different reasons. During the study, 392 patients were admitted to the G-ICU; of these, 214 required MV. The weaning process was started in 154 cases. Fifty-four patients were excluded from the study, and 24 were not extubated from MV. A total of 76 patients were finally extubated and analyzed. VARIABLES OF INTEREST: Vd/Vt was calculated as the ratio (PaCO(2)-Pє CO(2))/PaCO(2), with the recorded parameters. RESULTS: Logistic regression analysis showed a significant association between the Vd/Vt and extubation failure, with OR=1.52 (95%CI 1.11 to 2.09, p=0.008). The area under the ROC curve with respect to the prediction of extubation failure according to the Vd/Vt value was 0.94 (95%CI 0.86 to 0.98, p<0.0001). CONCLUSIONS: Vd/Vt is a powerful predictor of extubation failure in patients on MV.

[Lung transplantation using donors 55 years and older]. / Trasplante pulmonar con donantes de edad marginal (≥ 55 años).

OBJECTIVE: We analyzed short, medium and long-term mortality in transplant recipients who received lungs from donors aged 55 years or more. PATIENTS AND METHODS: All patients who underwent lung transplantation from donors aged 55 years or more were included. The association between the different study variables and early death and death at 1 year and 5 years was studied. A logistic regression model was used to study the association between early death and variables with a trend towards significance (P<.2) in the bivariate analysis. The risk factors for mortality at 1 year and 5 years were analyzed with a Cox regression model. The Kaplan-Meier method was used to analyze survival. RESULTS: A total of 33 patients were included. The probability of survival was 90.9%, 78.5% and 44.8% at 1 month, 1 year, and 5 years after lung transplantation, respectively. The elevated age of the recipient (P=.16) and single-lung transplantation (P=.09) were the variables associated to or with a trend towards significant associations with mortality. CONCLUSIONS: The final decision to accept a lung graft should be based on individual evaluation of each donor and recipient. However, given the lack of lung donors, donors aged 55 years or more should be considered for lung transplantation.

[Traumatic dissection of the internal carotid artery by a safety belt: a report of two cases]. / Disección traumática de la arteria carótida interna por el cinturón de seguridad: descripción de dos casos.

Traumatic internal carotid artery dissection secondary to blunt trauma is a rare event accounting for 0.08 to 0.4% of all traumatic lesions. The spectrum of traumatic lesions that can affect the internal carotid artery includes minor lesions like spasm, intimal tears, or mural contusions and serious lesions like pseudoaneurysms and complete occlusion. Delayed clinical presentation is typical and can include headache, hemiparesis, partial Horner's syndrome, and cranial nerve palsy. Embolization secondary to the dissection can have devastating effects because it may cause ischemic stroke. Traumatic internal carotid artery dissection after safety belt trauma is very rare; it is usually due to direct cervical trauma on the side of the shoulder fixation point, which causes external bruising along the pathway of the safety belt. We present two cases of traumatic internal carotid artery dissection with concomitant cerebral infarcts caused by safety belts; we discuss the clinical, diagnostic, and therapeutic aspects of this lesion.

Two cases of cyclic vomiting syndrome in systemic autoimmune conditions: SLE and autoimmune hepatitis.

Vomiting directly attributable to SLE occurs in approximately 8% of patients, and its causes are sometimes obscure when common conditions are ruled out. Cyclic vomiting syndrome is a common functional disorder which usually starts from childhood. We report the first two cases of patients affected by systemic autoimmune conditions associated to cyclic vomiting syndrome. Identification and proper treatment may guide to diagnosis and alleviate neglected manifestations of autoimmune patients.

[Analysis of subdural intracraneal empyemas in a third level hospital]. / Análisis de los empiemas subdurales intracraneales en un hospital de tercer nivel.

INTRODUCTION: Intracranial subdural empyema (ISE) is an infrequent infectious disorder of diverse etiology and difficult to diagnose because of its non-specific clinical features. PATIENTS AND METHODS: Retrospective study of patients diagnosed of ISE in a third-level university hospital in a 15-year period. RESULTS: Five men were included (mean age: 39.3 years). The most frequent primary source of infection was otic and sinusal (60%). The initial clinical manifestations were fever, headache, alteration of consciousness, and neurological focal symptoms. The mean time elapsed between onset of symptoms and diagnosis was 3.6 days. Diagnosis was performed by computed tomography in all patients. ISE was localized in the left hemisphere in 60% of cases mainly affecting the parietal lobe (80%). Anaerobic and streptococci germs were the most frequently isolated microorganisms. Therapy was based on antibiotics and surgical drainage in 100% of the cases. The surgical procedure used in the evacuation of empyema was craniotomy in all the patients. The mean time elapsed between diagnosis and surgery was 8.4 days. The mean Intensive Care Unit stay was 12.8 days, whereas the overall mean in-hospital stay was 45.2 days. Mortality was 40%. CONCLUSION: ISE, although infrequent, displays a high morbimortality that can be reduced with an early therapeutic approach which may include the surgical evacuation in all the cases.

[Evaluation of the pre-operative exercise capacity as survival marker in the lung transplant recipients]. / Valoración de la capacidad preoperatoria al ejercicio como factor predictivo de supervivencia en enfermos sometidos a trasplante pulmonar.

OBJECTIVE: To make an independent evaluation of the capacity for exercise as a predictive factor in lung transplant recipients. DESIGN: Retrospective study. SCOPE: Lung transplant unit of the Intensive Care Unit (ICU) of a university hospital. PATIENTS: We analyzed 132 lung transplants in a total of 130 patients. The patients were monitorized up to June 18, 2005 or their death. VARIABLES OF INTEREST: An evaluation was made of their pre-operative exercise capacity with the 6-minute walking test (6MWT). Long-term survival in relationship with the walking test value was also assessed. The survival curves were estimated using the Kaplan-Meier method. Comparison between curves was made with the Log-Rank methods and the hazard ratios were estimated by Cox regression. RESULTS: The association between mortality and the walking test value showed a hazard ratio of 0.99 (95% CI: 0.99-1.00) per metric unit (meter), (p = 0.282). The patients were classified according to the distance covered in the 4 groups: group 1 (distance covered less than 100 meters), group II (distance covered between 101-200 meters), group III (distance covered between 201 and 300 meters) and group IV (distance greater than 301 meters). No significant differences were found when comparing the survival curves of the four groups (p = 0.709). The multivariant analysis also did not show any statistical significance. CONCLUSIONS: We do not believe that the distance covered in the 6MWT conducted in the study protocol in the lung transplant candidates is useful as a marker to predict long-term mortality in patients undergoing lung transplant.

[Training in the care of the critical and multiple-injured patient: role of clinical simulation]. / Formación en la asistencia al paciente crítico y politraumatizado: papel de la simulación clínica.

Clinical simulation is suggested as a new educational instrument to learn and train in different medical skills. It is conceived as a new method that integrates scientific knowledge and human factors. Experience with these systems has been limited up to now, but it is now being widely accepted since it seems to accelerate acquisition of skills and knowledge in a safe setting, that is, without risk for the patient. However, its effect on clinical performance has not been validated yet. They are two types of simulators for intensive cares: screen based and human patient simulator (HPS). These systems make it possible to simulate different situations that require the application of action protocols or the management of new drugs in the clinical practice, promoting the rational use of resources in urgent care of the critical and multiple-injured patients. The limiting factors that prevent the expansion of the simulation for clinical training are its high cost, human resources needed, and the difficulties to assess the effectiveness of the training in real situations.

[Herpetic encephalitis in adults: 23 cases]. / Encefalitis herpética en adultos: 23 casos.

OBJECTIVE: To study the clinical presentation, diagnosis, treatment and prognosis of the herpetic encephalitis in our environment. MATERIAL AND METHOD: During the past 12 years, 23 adults (age > 15 years) were treated for herpetic encephalitis in our centre. RESULTS: There were 14 males and 9 females. Ages ranged from 18 to 84 years (mean, 52.30 +/- 18.64 years). The hospital stay ranged from 5 to 64 days (mean, 26.74 +/- 15.41 days). Eleven patients were managed in the intensive care unit and nine patients required mechanical ventilation. The most frequent clinical features they were the level of conscience decrease and fever. The lymphocytic pleiocytosis was the most frequent discovery in cerebrospinal fluid. The temporal lobe lesions in the computed tomography scan appeared in 14 patients (61%). Four patients died, seven patients were asymptomatic or with minimum sequels and twelve patients developed they were disabled. CONCLUSIONS: The herpetic encephalitis is an uncommon illness. Intravenous acyclovir is recommended treatment and the corticosteroids use is controverted. The delay in the treatment beginning worsens the prognosis. Less than a third of the patients achieve the functional independence to discharge hospital.

[Varicella pneumonia in adults: 30 cases]. / Neumonía varicelosa en adultos: 30 casos.

OBJECTIVES: During the past 10 years, 30 adults (age > 15 years) were treated for varicella pneumonia in our centre. METHODS: There were 16 males and 14 females. Ages ranged from 15 to 58 years (mean, 32.73+/-7.67 years). Twenty-seven patients (90%) were non-pregnant adult smokers and three patients (10%) were pregnant women. The hospital stay ranged from 4 to 57 days (mean, 14.96+/-12.02 days). RESULTS: Seven patients (23.3%) were managed in the intensive care unit and two patients (6,6%) required mechanical ventilation. The most common radiographic findings were interstitial infiltrates in twenty-one patients (70%) and interstitial-alveolar infiltrates in seven patients (23.3%). Physical examination of the chest did not reveal abnormalities in twenty patients (66,6%). Fifteen patients (50%) were severely hipoxic with pO2/FiO2 ratio less than 300. Twelve patients (40%) presented thrombocytopenia and fifteen (50%) presented hyponatremia. The most frequent clinical features included: fever (100%), dry cough (86.6%), dysnea (66.6%) and chest pain (50%). One patient (3.3%) died. Three patients (10%) developed asthma and one other patient developed pulmonary fibrosis. CONCLUSIONS: Smoking is associated with an increase incidence of varicella pneumonia in adults. A chest x-ray should be practised in all cases of varicella in adults and they all should also be admitted to hospital. Intravenous aciclovir is recommended for treatment of varicella pneumonia in adults and in seriously ill patients the association of corticosteroids should be considered.

[Cardiac Tamponade after on a guide changing of a central venous catheter for total parenteral nutrition. Could it be avoided?]. / Taponamiento cardíaco tras cambio de catéter venoso central, sobre guía, para nutrición parenteral total. Lo podemos evitar?

Catheterization of central veins is a routine process, especially in severely-ill patients. It is a technique associated with multiple potential complications, fortunately infrequent, depending on the skill with which it is performed. Cardiac blockade is one of these infrequent complications with a high mortality. We describe a case in which suspicion, early diagnosis, and immediate manipulative treatment allowed a successful recovery of the patient. In addition, the literature is reviewed and possible mechanisms involved in these episodes are discussed.

Acinetobacter bacteraemia in a teaching hospital, 1989-1998.

Background: The mortality rate from bacteraemia is one of the highest among infections in hospitals, especially in the intensive care unit (ICU). Recently, an increase in nosocomial bacteraemia caused by gram-negative resistant pathogens has been observed. In this work we review the clinical and laboratory findings of adult patients with Acinetobacter bacteraemia in order to identify risk factors associated with mortality. Methods: A retrospective review of the medical records of patients with Acinetobacter bacteraemia identified by blood cultures from the Diagnostic Microbiology Laboratory was conducted between January 1989 and March 1998. Results: We identified 59 cases of Acinetobacter bacteraemia. Most of the infections (71%) were nosocomial; the majority occurred in the Department of Internal Medicine (28.8%), followed by Haematology (27%) and the ICU (23%). A. lwoffii was isolated in 52.5% of cases and A. baumannii in 47.5%. The related mortality was 17%. Staying in the ICU was associated with A. baumannii bacteraemia (P<0.004). An intravascular catheter was the leading source of infection (37%). Main risk factors were mechanical ventilation (28%), parenteral nutrition (23%) and the presence of a urinary catheter (22%). In the multivariate analysis the independent prognostic factors for mortality were the presence of shock (P<0.05) and the severity of the underlying disease, according to the classification of McCabe (P<0.05). Conclusions: The incidence of Acinetobacter bacteraemia has increased in the last decade, mainly since 1995. The development of septic shock and the severity of the underlying disease appear to be associated with an increase in mortality.