Sangrado intraoperatorio de amigdalectomía en población pediátrica. Influencia de factores quirúrgicos y anestésicos / Intraoperative bleeding of tonsillectomy in pediatric patients. Effects of surgical and anesthesia technique

INTRODUCTION: Tonsillectomy with or without adenoidectomy is one of the most frequent surgeries in the pediatric population. It has become predomi- nantly an outpatient procedure. Therefore, it is of utmost importance identi- fying the factors that influence the intraoperative bleeding to prevent posto- perative complications and rehospitalization. MATERIAL AND METHODS: An observational cross-sectional study was carried out. Patients between 1 and 14 years old that underwent to tonsillectomy with or without adenoidectomy since November 2015 to May 2017 were included. 709 cases were evaluated. Intraoperative bleeding was assessed by the volumetric method. A multivariate analysis was performed using a generalized linear regression model. RESULTS: The average intraoperative bleeding was estimated in 1.9 ml/kg (95% CI: 1.7 -2.05). The use of propofol (30% increase in bleeding) and surgical time (2% increase for every minute) were risk factors. The use of electrocautery was as- sociated with a 50% decrease in bleeding in comparison with conventional dis- section (p = 0.001). CONCLUSION: The use of propofol and a prolonged surgical time were risk factors for intraoperative bleeding. The use of electrosurgery was a protective factor.

INTRODUCCIÓN: La amigdalectomía con o sin adenoidectomía, es una de las cirugías más frecuente en población pediátrica. Desde hace varios años se ha vuelto una intervención predominantemente ambulatoria, por lo que lograr identificar los factores que influyen en el sangrado intraoperatorio es de suma importancia para prevenir complicaciones postoperatorias y reshospitalización. MATERIAL Y MÉTODO: Se realizó un estudio observacional de corte-transversal. Se incluyó a pacientes entre 1 y 14 años sometidos a amigdalectomía con o sin adenoidectomía entre noviembre de 2015 y mayo de 2017, obteniendo un total de 709 casos evaluados. Se determinó el sangrado intraoperatorio de forma volumétrica. Posteriormente, se realizó un análisis multivariado con un modelo de regresión lineal generalizado. RESULTADOS: Se cuantificó el sangrado intraoperatorio promedio en 1,9 ml/kg (IC 95%; 1,7-2,05). El uso de propofol (aumento del 30% del sangrado) y tiempo quirúrgico (2% por cada incremento de un minuto) fueron factores de riesgo. Mientras que el uso de electro bisturí se asoció con una disminución del 50% en relación al no uso (p = 0,001). CONCLUSIONES: Fueron factores de riesgo para sangrado intraoperatorio el uso de propofol y un tiempo quirúrgico prolongado. El uso de electrobisturí constituyó un factor protector.

Exploring alternatives to reduce economical costs associated with FNA pre-treatment of waste activated sludge.

Recent studies have shown the effectiveness of Free Nitrous Acid (FNA) pre-treatment in enhancing sludge biodegradability and improving its methane production potential. FNA is regarded as an environmental friendly pre-treatment which can be easily applied when a source of nitrite is present in wastewater treatment plants. However, when nitrite is not available and needs to be purchased, this treatment can become less attractive due to the costs associated to nitrite. In order to overcome this possible limitation, two different strategies to optimize the use of nitrite during FNA treatment were investigated: i) Recovering NO2- after the pre-treatment is completed; and ii) Concentrating the sludge before FNA pre-treatment. Results show that recovering NO2- from the pre-treated sludge is not suitable due to the loss of soluble organic matter present in the supernatant after the pre-treatment. However, concentrating the sludge before the pre-treatment seems a good strategy to optimize the use of nitrite.

Effect of free nitrous acid pre-treatment on primary sludge at low exposure times.

The present study was undertaken to investigate the effect of different free nitrous acid (FNA) concentrations at low pre-treatment times (PTs) (1, 2 and 5h) and without pH control with mild agitation on primary sludge (PS) biodegradability and methane production (MP). Increasing PTs resulted in an increase in the solubility of the organic matter (around 25%), but not on cell-mortality (>75% in all the cases with FNA) and neither on methane generation. FNA pre-treatment at low PTs improve MP (around 16% at PT of 1h and 650mg N-NO2-/L). However, a similar improvement was found with mild agitation of PS without FNA at 2 and 5h. Taking into account the potential costs associated with the FNA pre-treatment, a mild agitation without FNA would be preferred to enhance MP in PS.

Assessment of free nitrous acid pre-treatment on a mixture of primary sludge and waste activated sludge: Effect of exposure time and concentration.

Free nitrous acid (FNA) has been shown to enhance the biodegradability of waste activated sludge (WAS) but its effectiveness on the pre-treatment of mixed sludge is not known. This study explores the effectiveness of four different FNA concentrations (0, 2.49, 3.55, 4.62mgN-HNO2/L) and three exposure times (2, 5, 9h) lower than the ones reported in literature (24h) on WAS characteristics and specific methane production (SMP). FNA pre-treatment reduced sludge cell viability below 10% in all cases after an exposure time of 5h, increasing the solubility of the organic matter. The treated mixed sludge was used as substrate for the biochemical methane production tests to assess its SMP. Results showed a significant increase (up to 25%) on SMP when the sludge was pretreated with the lowest FNA concentration (2.49mgN-HNO2/L) during 2 and 5h but did not show any improvement at longer exposure times or higher FNA concentrations.

Influence of dissolved oxygen concentration on the start-up of the anammox-based process: ELAN®.

The anammox-based process ELAN® was started-up in two different sequencing batch reactor (SBR) pilot plant reactors treating municipal anaerobic digester supernatant. The main difference in the operation of both reactors was the dissolved oxygen (DO) concentration in the bulk liquid. SBR-1 was started at a DO value of 0.4 mg O2/L whereas SBR-2 was started at DO values of 3.0 mg O2/L. Despite both reactors working at a nitrogen removal rate of around 0.6 g N/(L d), in SBR-1, granules represented only a small fraction of the total biomass and reached a diameter of 1.1 mm after 7 months of operation, while in SBR-2 the biomass was mainly composed of granules with an average diameter of 3.2 mm after the same operational period. Oxygen microelectrode profiling revealed that granules from SBR-2 where only fully penetrated by oxygen with DO concentrations of 8 mg O2/L while granules from SBR-1 were already oxygen penetrated at DO concentrations of 1 mg O2/L. In this way granules from SBR-2 performed better due to the thick layer of ammonia oxidizing bacteria, which accounted for up to 20% of all the microbial populations, which protected the anammox bacteria from non-suitable liquid media conditions.