Microcirculatory changes during cardiac surgery with cardiopulmonary bypass. / Alteraciones microcirculatorias en cirugía cardíaca con circulación extracorpórea.

OBJECTIVE: To evaluate microcirculation in intermediate and high mortality risk patients undergoing cardiac surgery (CS) with cardiopulmonary bypass (CPB). PATIENTS AND METHODS: The study included 22 patients with a Euroscore >3. Using the Videomicroscopy Side Stream Dark Field system, and evaluation was made of, capillary density, proportion of perfused capillaries, density of perfused capillaries, microcirculatory flow index (MFI), and heterogeneity flow index. Three to five video sequences were recorded: after induction of anaesthesia (T1), at the beginning of the CPB (T2), before finalising CPB (T3), at the end of the surgery, and before the patient was transferred to Intensive Care Unit (T4). Mean arterial pressure decreased, while the blood lactate increased significantly, when comparing the initial and final values (P<.05). MFI increased significantly in T3 and T4 (P<.05) with regards to the initial values. When the patients with and without postoperative complications were compared, significant differences were found in, Euroscore, left ventricular ejection fraction, and MFI in T3. CONCLUSIONS: in patients with intermediate/high preoperative risk, CS and CBP can involve an increase in MFI and blood lactate at the end of the study. These alterations suggest the possibility of a functional microcirculatory shunt at tissue perfusion level, secondary to the surgical injury and the CPB. Further investigation is needed to have a better understanding of the mechanisms involved.

Treatment of vitreomacular traction syndrome with autologous plasmin enzyme.

PURPOSE: To determine whether intravitreal injection of autologous plasmin enzyme (APE) is effective in vitreomacular traction syndrome (VMTS) by improving visual acuity and restoring macular morphology. METHODS: A prospective study of 11 consecutive patients diagnosed with VMTS in the Ophthalmology Department from January to May, 2011. INCLUSION CRITERIA: best corrected visual acuity (BCVA) less than 0.5, and vitreomacular attachment in foveal area resulting in macular thickness>250 microns diagnosed by optical coherence tomography (Cirrus OCT, Carl Zeiss Meditec, Inc, Oberkochen, Germany). EXCLUSION CRITERIA: active proliferative diabetic retinopathy, axial myopia>26mm, vitrectomy, glaucoma, previous intravitreal injections and previous rhegmatogenous detachment. One to 3 monthly intravitreal injections of 0.2ml of APE were applied, interrupting if posterior vitreous detachment was attained. Wilcoxon's test was used for statistical analysis. RESULTS: A total of 12 eyes of 11 patients were treated. A complete posterior vitreous detachment was achieved in 4 (33%) eyes at the end of the study, 2 of them with one injection, and 2 with 3 monthly injections. Improvement of BCVA was statistically significant (P=.017) and the decrease in central macular thickness also was statistically significant (P=.016). There was only one complication: intraocular hypertension after injection that subsided with a new paracentesis. CONCLUSIONS: Intravitreal APE injections avoided vitrectomy in VMTS in one in every 3 patients.

Fluid dynamic analysis of a continuous stirred tank reactor for technical optimization of wastewater digestion.

Continuous stirred tank reactors (CSTR) are widely used in wastewater treatment plants to reduce the organic matter and microorganism present in sludge by anaerobic digestion. The present study carries out a numerical analysis of the fluid dynamic behaviour of a CSTR in order to optimize the process energetically. The characterization of the sludge flow inside the digester tank, the residence time distribution and the active volume of the reactor under different criteria are determined. The effects of design and power of the mixing system on the active volume of the CSTR are analyzed. The numerical model is solved under non-steady conditions by examining the evolution of the flow during the stop and restart of the mixing system. An intermittent regime of the mixing system, which kept the active volume between 94% and 99%, is achieved. The results obtained can lead to the eventual energy optimization of the mixing system of the CSTR.

[The changes in the oxygen saturations in the superior vena cava and the pulmonary artery are not the same during cardiac surgery]. / Las tendencias en el tiempo de las saturaciones de oxígeno en la vena cava superior y la arteria pulmonar no son equivalentes en cirugía cardiaca.

OBJECTIVE: To evaluate the changes over time (trend) in sign and magnitude for SSVO2 and SVO2 during and after cardiac surgery. PATIENTS AND METHODS: A prospective and observational study was conducted on 34 cardiac surgery patients. Venous blood samples were taken simultaneously from the introductor (SVCO2) and distal (SVO2) port of the pulmonary artery catheter at predefined intervals. Systemic and pulmonary hemodynamic variables were measured at the same time. The trend was calculated as the difference between 2 consecutive measurements (tSO2). Data were processed with ANOVA for multiple comparisons, Pearson correlation coefficient and Bland-Altman analysis. RESULTS: There was a significant correlation between SVCO2 and tSVO2 (R(2)=0.55), the mean of the differences was 0.36±7.75%, and the limits of agreement ranged from -15.1 to 15.9%. The sign of the trend was similar in 85.1% of the paired data. However, the magnitude of the changes in tSVCO2 and tSVO2 were not always equivalent. Between 0 and 5% of the change in the tSVCO2 was coincident with only 44.7% of the tSVO2. A wide variation was found between both trends when the signs and magnitudes of the changes were taken into account. CONCLUSIONS: When considering the sign and magnitude, the change over time of central venous O2 saturations were not interchangeable in cardiac surgery patients. Clinical decisions based exclusively on tSVCO2 monitoring should be taken with caution.

[A protocol for the treatment of retinopathy of prematurity in Spain]. / Protocolo de tratamiento de la retinopatía del prematuro en España.

OBJECTIVE: To prepare a protocol for the treatment of retinopathy of prematurity (ROP) agreed by the majority of Spanish ophthalmologists dedicated to this topic. MATERIAL AND METHOD: A draft of the protocol was produced taking into account the experience of the participants and up to date publications. This draft was corrected by all the ophthalmologists participating in the project, and the final document was agreed by all of them. RESULTS: We present general guidelines as an aid for the treatment of ROP, including treatment criteria, treatment methods, a calendar of action, and follow-up. CONCLUSIONS: It is important to have a common working protocol for the treatment of ROP to improve care and to avoid mistakes. Although individual Hospitals may adapt the protocol to their daily activity, it is recommended that there is a minimal working protocol agreed by most of professionals dedicated to pediatric ophthalmology in Spain.

Screening program for retinopathy of prematurity in Spain.

OBJECTIVE: To prepare a retinopathy of prematurity (ROP) screening program as agreed by most of Spanish ophthalmologists dedicated to this topic. MATERIALS AND METHODS: A draft of the protocol was produced taking into account the experience of the participants and current publications. This draft was corrected by all the ophthalmologists participating in the project and the final document produced was agreed by all of them. RESULTS: We present general guidelines to help in the screening of ROP, including treatment criteria, treatment methods, and a calendar of action. CONCLUSIONS: It is important to have a common working protocol in the screening of ROP to improve the action and to avoid mistakes. Although individual Hospitals may adapt the protocol to their daily activity, it is recommended that there is a minimal working protocol agreed by most of professionals dedicated to pediatric ophthalmology in Spain.

Contribution of the coronary sinus blood to the pulmonary artery oxygen saturation gradient in cardiac surgery patients.

BACKGROUND: The coronary sinus oxygen saturation (SO2) can affect the oxygen saturation of the superior vena cava (superior cava SO2) and the pulmonary artery (pulmonary artery SO2), causing a gradient between the latter two (ΔSO2), as has been observed in different physiological and pathological conditions. The objective of the study was to evaluate the different determinants of ΔSO2 in cardiac surgery patients. METHODS: An observational, prospective study was carried out on 18 patients undergoing elective cardiac surgery. Blood samples were obtained from the superior vena cava, the pulmonary artery, the inferior vena cava, and the coronary sinus before extracorporeal circulation. RESULTS: The following measurements were made: superior cava SO2, pulmonary artery SO2, coronary sinus SO2, and inferior cava SO2. The mean values (± SD) were as follows: superior cava SO2=76.4±12.6%; inferior cava SO2=72.7±15.8%; coronary sinus SO2=46.6±17.0%; and pulmonary artery SO2=71.9±12.9%. The ΔSO2 was 4.5±5.5%. The average oxygen saturation (SO2avg=[Superior cava SO2 + inferior cava SO2]/2) was 74.6±13.7%. The superior cava SO2 was significantly higher than the pulmonary artery SO2, and the ΔSO2 was significantly different from zero (P≤0.05). No significant differences were found between the superior cava SO2 and the inferior cava SO2, and both were significantly different from the coronary sinus SO2. The difference between SO2avg and the pulmonary artery SO2 was 2.74±4.4%. CONCLUSION: The observed ΔSO2 could only be explained by dilution of the superior cava SO2 with blood with a lower SO2. The coronary sinus blood contributed to generate this gradient.

[Screening for retinopathy of prematurity. Our experience about limits of birth weight, post-conceptional age and other risk factors]. / Despistaje de la retinopatía del prematuro. Nuestra experiencia sobre los límites de peso al nacer, edad gestacional y otros factores de riesgo.

PURPOSE: To assess the features of Retinopathy of Prematurity (ROP) in a Neonatal Intensive Care Unit during 8 years, analyzing the usefulness of the criteria in the screening protocol and the risk factors relating to the disease. METHODS: A retrospective study of the infants included in the screening program for ROP. The sensitivity of the criteria of birth weight (BW) < 1,500 g, post-conceptional age (PCA) < 32 weeks and subjective pediatric criteria (SPC) in the screening program were evaluated and compared with the incidence of ROP, and the need for treatment in these patient groups. Statistical analysis for ROP and no-ROP was then applied to the risk factors BW, PCA, oxygen therapy, and intercurrent diseases. RESULTS: Forty of 303 infants studied had ROP (13.2%). In ROP cases, 31 (77.5%) had spontaneous regression and 9 (22.5%) needed treatment. The screening program included 144 children with BW < 1,500 g and 159 children with BW > 1,500 g. The incidence of ROP was 26.4% in the first group and 1.3% in the second group (p < 0.001). Two cases were detected with a BW > 1,500 g but with a PCA < 32 weeks, and neither required treatment. There were 84 cases included because of SPC (27.7%); no cases of ROP were detected in these. The only independent risk factor found in a multivariant analysis was birth weight. CONCLUSIONS: None of the children included with a BW > 1500 g required treatment for ROP, but several cases of ROP could be missed by using this criteria only. SPC must be restricted in the screening program.

Despistaje de la retinopatía del prematuro. Nuestra experiencia sobre los límites de peso al nacer, edad gestacional y otros factores de riesgo / Screening for retinopathy of prematurity. Our experience about limits of birth weight, post-conceptional age and others risk factors

Objetivo: Registrar las características de la Retinopatíade la Prematuridad (RP) en una unidad neonatala lo largo de 8 años, analizando los criterios delprotocolo de despistaje y los factores de riesgo asociados.Métodos: Estudio retrospectivo de los prematurosincluidos en el protocolo de despistaje. Evaluaciónde la sensibilidad de los criterios Peso al nacer (PN) 1.500 gr fue 1,3% (p 1500 gr y EG 1.500 gr requirió tratamiento,pero usando sólo este criterio pueden no detectarsealgunos casos de RP. La inclusión de niños por CSPdebe restringirse

Purpose: To assess the features of Retinopathy ofPrematurity (ROP) in a Neonatal Intensive CareUnit during 8 years, analyzing the usefulness of thecriteria in the screening protocol and the risk factorsrelating to the disease.Methods: A retrospective study of the infants includedin the screening program for ROP. The sensitivityof the criteria of birth weight (BW) 1,500 g. Theincidence of ROP was 26.4% in the first group and1.3% in the second group (p 1,500 g but with a PCA 1500g required treatment for ROP, but severalcases of ROP could be missed by using this criteriaonly. SPC must be restricted in the screening program

[Unilateral papilledema in pseudotumor cerebri]. / Papiledema unilateral en pseudotumor cerebri.

CASE REPORT: We describe a fifty year old woman who complained of headache and transient blurring vision in her left eye. Visual acuity was normal and there was no pupillary defect. Ophthalmoscopy revealed left optic disc edema, whereas the right eye was tipified as normal. After discarding an ocular or orbital condition, neuroimaging and lumbar puncture leaded to diagnosis of Pseudotumor Cerebri. Symptoms improved after Acetazolamide treatment and lumbar punctures. A more detailed fundoscopy, as suggested ocular ultrasonography and CT scanner findings, revealed a mild papilledema in the other eye. DISCUSSION: Unilateral or apparently unilateral papilledema are sometimes signs of intracranial hypertension. Our case report highlights the difficult diagnosis of highly asimmetric papilledemas, and the possible delay of a neurological study.

Papiledema unilateral en pseudotumor cerebri / Unilateral papilledema in pseudotumor cerebri

Presentamos una paciente de 50 años que aquejaba cefaleas y episodios de oscurecimiento transitorio de la visión en su ojo izquierdo. A la exploración la visión era normal y no había defecto en el reflejo fotomotor. La funduscopia reveló un gran edema de papila en dicho ojo, mientras que el otro fue considerado normal a la exploración clínica. Tras descartarse patologías oculares y orbitarias, las pruebas de neuroimagen y la punción lumbar condujeron al diagnóstico de pseudotumor cerebri, que mejoró tras el tratamiento oral con acetazolamida y punciones lumbares. Una exploración más detallada del fondo de ojo, como sugerían los hallazgos de la ecografía ocular y el TAC, reveló un leve papiledema en el otro ojo. Discusión: Debe tenerse en cuenta que los papiledemas unilaterales, o aparentemente unilaterales, también son formas de presentación de la hipertensión intracraneal. Nuestro trabajo enfatiza las dificultades diagnósticas que un papiledema altamente asimétrico puede ocasionar, demorando a veces el estudio neurológico (AU)

Gastric intramucosal pH and intraluminal PCO2 during weaning from mechanical ventilation.

OBJECTIVE: To study the value of gastric intramucosal pH and gastric intraluminal PCO2 measurements to predict weaning outcome from mechanical ventilation. DESIGN: Prospective clinical study. SETTING: Intensive care medicine department of a university hospital. PATIENTS: Nineteen adult critically ill patients who were mechanically ventilated because of acute respiratory failure and were considered ready to be weaned. INTERVENTIONS: The patients were weaned with: synchronized intermittent mandatory ventilation plus positive end-expiratory pressure (SIMV+PEEP) or continuous positive airway pressure with pressure support ventilation (CPAP+PSV). A gastric tonometer was placed in all the patients. Tonometric, respiratory, and hemodynamic variables were measured during the weaning process. MEASUREMENTS: Hemodynamic variables, respiratory mechanics, pulmonary gas exchange, respiratory muscle force, spontaneous pattern of breathing, and the central control of breathing were recorded. Simultaneously, the intramucosal pH and gastric intraluminal PCO2 were measured. MAIN RESULTS: Eleven patients were successfully extubated and eight failed. The patients who failed showed higher values of mouth occlusion pressure, respiratory rate, and effective inspiratory impedance (mouth occlusion pressure/mean inspiratory flow). The intramucosal pH was initially 7.19 +/- 0.22 and decreased to 7.10 +/- 0.16 during the weaning process in patients who failed (p < .05). At the same time, the intramucosal pH showed a nonsignificant change from 7.36 +/- 0.07 to 7.32 +/- 0.07 in the patients who were successfully extubated. The intramucosal pH was statistically different when both groups were compared during the initial and the final evaluations (p < .05). For the initial evaluation, the sensitivity and specificity to predict weaning failure when the intramucosal pH was < or =7.30 were 0.88 (95% confidence interval [CI], 0.66-1) and 0.82 (95% CI, 0.59-1), respectively. The gastric intraluminal PCO2 was higher in patients who failed (p < .05). When gastric intraluminal PCO2 was . or =40 torr during the initial evaluation, weaning failure occurred with a sensitivity of 1 (95% CI, 0.31-1) and a specificity of 0.55 (95% CI, 0.26-0.84). CONCLUSIONS: Weaning failure was associated with gastric intramucosal acidosis. The intramucosal pH and gastric intraluminal PCO2 may be helpful to predict weaning outcome. Further controlled clinical trials in a larger group of patients are needed.

Method for collecting Hypoderma spp. (Diptera: Oestridae) larvae from cattle.

A new method for collecting 3rd-instar Hypoderma lineatum (Villers) and Hypoderma bovis (L.) is described. A procedure for carrying out chronobiological and other studies involving the life cycle of these flies is included. The larvae are collected from cattle using a dressing made of a circle of cardboard attached to a piece of tulle similar in color to the coat of the animal. These small cloth cages were attached to the animal skin with fast-drying contact glue wherever the swellings produced by 2nd- or 3rd-instar Hypoderma spp. had been previously detected. Each animal was inspected daily to detect the appearance of new larvae. This procedure allows the collection of each emerged larva without contact with other larvae and avoids friction of the cloth cages or dressing with the larvae, thus reducing larval death and increasing viability of the parasite.

Inhibitory effect of Escherichia coli endotoxin on skeletal muscle contractility.

OBJECTIVE: Endotoxemia in rabbits is associated with decreases in oxygen transport, tissue hypoxia, metabolic acidosis, and impaired oxygen extraction. In this study, we tested the hypothesis that endotoxin also inhibits skeletal muscle contractility directly. DESIGN: Randomized animal study. SETTING: Accredited animal research facility. SUBJECTS: New Zealand white rabbits of either sex, weighing 2.55 +/- 0.20 kg. INTERVENTIONS: We compared two groups of rabbits (n = 10 each) undergoing continuous electrical stimulation of the left hindlimb (maximal isometric twitch contraction at 0.25 Hz). One group (septic) was given an intravenous infusion of Escherichia coli endotoxin. The control group was subjected to decreases in cardiac output by inflating a balloon placed in the right ventricle. MEASUREMENTS AND MAIN RESULTS: Endotoxin or balloon inflation resulted in comparable decreases in cardiac output (49% and 53%, respectively). Hindlimb oxygen transport decreased to similar values for both groups (4.9 +/- 0.3 and 4.2 +/- 0.5 mL/min/kg, respectively). Systemic oxygen extraction ratio was greater in the control group (0.72 +/- 0.03) than in the septic group (0.55 +/- 0.04; p < .05). There were no differences in hindlimb oxygen extraction ratio. Decreases in hindlimb forces were greater in the septic group (42 +/- 4%) than in the control group (18 +/- 3%, p < .01). Force frequency curves obtained at the beginning and the end of the experiment showed greater fatigue in the septic group. CONCLUSIONS: The intravenous infusion of Escherichia coli endotoxin produces a direct inhibitory effect on skeletal muscle contractility in rabbits. This phenomenon is independent of decreases in oxygen transport and blood pH. Our data support the notion of a direct cellular effect of endotoxin, or of an associated cytokine, on skeletal muscle contractility. The mechanism responsible for this phenomenon is unknown.

Hydroxymalonate inhibits lactate uptake by the rabbit hindlimb.

Lactate uptake by skeletal muscle occurs under diverse conditions, including hypoxia and electrical stimulation. A possible metabolic fate of lactate in resting muscle is its conversion to pyruvate followed by carboxylation to malate in the cytosolic malic reaction. To test this hypothesis, we measured hindlimb lactate uptake in hypoxic mechanically ventilated rabbits. Rabbits were given intravenous infusions of hydroxymalonate, an inhibitor of the malic reaction (200 mM; n = 7), or normal saline (n = 7) at 1.1 ml/min. Hindlimb lactate uptake/release was calculated as femoral blood flow times the arteriovenous lactate difference. Saline or hydroxymalonate was infused continuously during sequential 30-min periods of normoxia (arterial PO2 approximately 150 Torr), hypoxemia (arterial PO2 approximately 30 Torr), and reoxygenation (arterial PO2 approximately 150 Torr). Hindlimb O2 transport decreased with hypoxemia, but O2 consumption remained unchanged in both groups. During hypoxemia there was net uptake of lactate by the hindlimb of the group given normal saline [4.5 +/- 0.9 (SE) mumol/min]. The hindlimb of the hydroxymalonate group continued to release lactate (-0.5 +/- 1.0 mumol/min). The inhibition of lactate uptake by hydroxymalonate supports the hypothesis that the malic reaction plays a major role in the metabolism of lactate by resting rabbit skeletal muscle.

Net uptake of lactate by rabbit hindlimb during hypoxia.

Lactate uptake by normoxic tissues is a pH-dependent phenomenon that occurs with increases in arterial lactate concentration. In this study we sought to determine the effect of hypoxia on lactate uptake by the rabbit hindlimb at different arterial blood pH (pHa). Two groups of rabbits were subjected to 20 min of arterial hypoxemia (PaO2 approximately 20 mm Hg). One group was allowed to maintain normal pHa (approximately 7.40 to 7.45; n = 5), whereas the other group was hyperventilated, resulting in hypocarbia and alkalemia (pHa > 7.50; n = 5). Lactate uptake was computed from measurements of femoral blood flow and the arterio-venous lactate difference. We found decreases in hindlimb O2 consumption during hypoxemia from 0.79 +/- 0.08 to 0.33 +/- 0.06 ml/min in the normal pH group (p < 0.01) and from 0.49 +/- 0.06 to 0.24 +/- 0.02 ml/min in the high pH group (p < 0.01). At that time there was net uptake of lactate by the hindlimb of the normal pH group (8.1 +/- 2.0 mumol/min; p < 0.001) and lactate release by the alkalemic group (1.61 +/- 1.0 mumol/min). Furthermore, hindlimb lactate uptake was associated with increased glucose consumption (p < 0.001). We hypothesize that the mechanisms responsible for lactate uptake by resting skeletal muscle during hypoxia may be similar to those that regulate lactate uptake during normoxic exercise.

Role of tissue hypoxia as the mechanism of lactic acidosis during E. coli endotoxemia.

We compared the hemodynamic and metabolic alterations produced in rabbits by similar decreases in cardiac output created by inflating a balloon placed in the right ventricle (n = 6) with those produced by an intravenous bolus of Escherichia coli lipopolysaccharide (LPS; SEP group; n = 6). We measured O2 consumption (VO2), O2 transport (TO2), and O2 extraction ratio (ERO2) for the whole animal and also for the left hindlimb. Both groups experienced similar decreases in cardiac output, systemic TO2, and VO2 and similar increases in ERO2. For the hindlimb, TO2 was similar, but VO2 and ERO2 were lower for the SEP group 30 min after LPS administration (P less than 0.05); however, this difference disappeared during the remainder of the experiment. Arterial lactate concentration was greater (P less than 0.05) for the SEP group. There were no differences in skeletal muscle PO2, measured with a multiwire surface electrode, or in cardiac and skeletal muscle concentrations of high-energy phosphates. We hypothesize that a direct effect of LPS on cellular metabolism may have resulted in greater arterial lactate concentration for the SEP group.