Point Cloud Compression: Impact on Object Detection in Outdoor Contexts.

Increasing demand for more reliable and safe autonomous driving means that data involved in the various aspects of perception, such as object detection, will become more granular as the number and resolution of sensors progress. Using these data for on-the-fly object detection causes problems related to the computational complexity of onboard processing in autonomous vehicles, leading to a desire to offload computation to roadside infrastructure using vehicle-to-infrastructure communication links. The need to transmit sensor data also arises in the context of vehicle fleets exchanging sensor data, over vehicle-to-vehicle communication links. Some types of sensor data modalities, such as Light Detection and Ranging (LiDAR) point clouds, are so voluminous that their transmission is impractical without data compression. With most emerging autonomous driving implementations being anchored on point cloud data, we propose to evaluate the impact of point cloud compression on object detection. To that end, two different object detection architectures are evaluated using point clouds from the KITTI object dataset: raw point clouds and point clouds compressed with a state-of-the-art encoder and three different compression levels. The analysis is extended to the impact of compression on depth maps generated from images projected from the point clouds, with two conversion methods tested. Results show that low-to-medium levels of compression do not have a major impact on object detection performance, especially for larger objects. Results also show that the impact of point cloud compression is lower when detecting objects using depth maps, placing this particular method of point cloud data representation on a competitive footing compared to raw point cloud data.

Single trial detection of error-related potentials in brain-machine interfaces: a survey and comparison of methods.

Objective.Error-related potential (ErrP) is a potential elicited in the brain when humans perceive an error. ErrPs have been researched in a variety of contexts, such as to increase the reliability of brain-computer interfaces (BCIs), increase the naturalness of human-machine interaction systems, teach systems, as well as study clinical conditions. Still, there is a significant challenge in detecting ErrP from a single trial, which may hamper its effective use. The literature presents ErrP detection accuracies quite variable across studies, which raises the question of whether this variability depends more on classification pipelines or on the quality of elicited ErrPs (mostly directly related to the underlying paradigms).Approach.With this purpose, 11 datasets have been used to compare several classification pipelines which were selected according to the studies that reported online performance above 75%. We also analyze the effects of different steps of the pipelines, such as resampling, window selection, augmentation, feature extraction, and classification.Main results.From our analysis, we have found that shrinkage-regularized linear discriminant analysis is the most robust method for classification, and for feature extraction, using Fisher criterion beamformer spatial features and overlapped window averages result in better classification performance. The overall experimental results suggest that classification accuracy is highly dependent on user tasks in BCI experiments and on signal quality (in terms of ErrP morphology, signal-to-noise ratio (SNR), and discrimination).Significance.This study contributes to the BCI research field by responding to the need for a guideline that can direct researchers in designing ErrP-based BCI tasks by accelerating the design steps.

Development and validation of a clinical score for early diagnosis of constipation in critically ill children.

Constipation affects almost 50% of critically ill pediatric patients and is related to their morbidity and mortality. However, little attention is paid to it and it is diagnosed late and when there are already complications. The objective of this study is to develop and validate a score to identify critically ill children with high risk of constipation 48 h after admission. A single center two phase-study was carried out; the first one (retrospective observational study) to develop the score and the second one to validate it in another prospective observational study. Children between 15 days of life and 18 years old admitted to the PICU for more than 3 days were included. Demographic and clinical data during the first 48 h after PICU admission were collected. Univariate and multivariate analysis and ROC curves were used to develop and validate the score. Data from 145 patients (62.8% boys) with a mean age of 34.9 ± 7.3 months were used to develop the score. Independent factors identified to develop the score were: weight > 7 kg, admission to PICU after surgery, need of vasoconstrictors, doses of fentanyl ≥ 2 mcg/kg/h, and initiation of enteral nutrition later than 48 h after admission. Two cut-off values were identified to set low constipation risk (< 5.7 points) and high constipation risk (> 6.2 points). This score was validated in 124 patients showing a sensibility of 63.2%, specificity of 95.5% and a positive/negative predictive values (P/NPV) of 100% and 82.1% respectively to identify constipated patients. This is the first score to identify high constipation risk in critically ill children. This score is easy to apply, and internal validation has shown a PPV of 100%.

Visuo-auditory stimuli with semantic, temporal and spatial congruence for a P300-based BCI: An exploratory test with an ALS patient in a completely locked-in state.

BACKGROUND: Brain-computer interfaces (BCIs) are a promising tool for communication with completely locked-in state (CLIS) patients. Despite the great efforts already made by the BCI research community, the cases of success are still very few, very exploratory, limited in time, and based on simple 'yes/no' paradigms. NEW METHOD: A P300-based BCI is proposed comparing two conditions, one corresponding to purely spatial auditory stimuli (AU-S) and the other corresponding to hybrid visual and spatial auditory stimuli (HVA-S). In the HVA-S condition, there is a semantic, temporal, and spatial congruence between visual and auditory stimuli. The stimuli comprise a lexicon of 7 written and spoken words. Spatial sounds are generated through the head-related transfer function. Given the good results obtained with 10 able-bodied participants, we investigated whether a patient entering CLIS could use the proposed BCI. RESULTS: The able-bodied group achieved 71.3 % and 90.5 % online classification accuracy for the auditory and hybrid BCIs respectively, while the patient achieved 30 % and chance level accuracies, for the same conditions. Notwithstanding, the patient's event-related potentials (ERPs) showed statistical discrimination between target and non-target events in different time windows. COMPARISON WITH EXISTING METHODS: The results of the control group compare favorably with the state-of-the-art, considering a 7-class BCI controlled visual-covertly and with auditory stimuli. The integration of visual and auditory stimuli has not been tested before with CLIS patients. CONCLUSIONS: The semantic, temporal, and spatial congruence of the stimuli increased the performance of the control group, but not of the CLIS patient, which can be due to impaired attention and cognitive function. The patient's unique ERP patterns make interpretation difficult, requiring further tests/paradigms to decouple patients' responses at different levels (reflexive, perceptual, cognitive). The ERPs discrimination found indicates that a simplification of the proposed approaches may be feasible.

A new error-monitoring brain-computer interface based on reinforcement learning for people with autism spectrum disorders.

Objective.Brain-computer interfaces (BCIs) are emerging as promising cognitive training tools in neurodevelopmental disorders, as they combine the advantages of traditional computerized interventions with real-time tailored feedback. We propose a gamified BCI based on non-volitional neurofeedback for cognitive training, aiming at reaching a neurorehabilitation tool for application in autism spectrum disorders (ASDs).Approach.The BCI consists of an emotional facial expression paradigm controlled by an intelligent agent that makes correct and wrong actions, while the user observes and judges the agent's actions. The agent learns through reinforcement learning (RL) an optimal strategy if the participant generates error-related potentials (ErrPs) upon incorrect agent actions. We hypothesize that this training approach will allow not only the agent to learn but also the BCI user, by participating through implicit error scrutiny in the process of learning through operant conditioning, making it of particular interest for disorders where error monitoring processes are altered/compromised such as in ASD. In this paper, the main goal is to validate the whole methodological BCI approach and assess whether it is feasible enough to move on to clinical experiments. A control group of ten neurotypical participants and one participant with ASD tested the proposed BCI approach.Main results.We achieved an online balanced-accuracy in ErrPs detection of 81.6% and 77.1%, respectively for two different game modes. Additionally, all participants achieved an optimal RL strategy for the agent at least in one of the test sessions.Significance.The ErrP classification results and the possibility of successfully achieving an optimal learning strategy, show the feasibility of the proposed methodology, which allows to move towards clinical experimentation with ASD participants to assess the effectiveness of the approach as hypothesized.

Cross-Subject Zero Calibration Driver's Drowsiness Detection: Exploring Spatiotemporal Image Encoding of EEG Signals for Convolutional Neural Network Classification.

This paper explores two methodologies for drowsiness detection using EEG signals in a sustained-attention driving task considering pre-event time windows, and focusing on cross-subject zero calibration. Driving accidents are a major cause of injuries and deaths on the road. A considerable portion of those are due to fatigue and drowsiness. Advanced driver assistance systems that could detect mental states which are associated with hazardous situations, such as drowsiness, are of critical importance. EEG signals are used widely for brain-computer interfaces, as well as mental state recognition. However, these systems are still difficult to design due to very low signal-to-noise ratios and cross-subject disparities, requiring individual calibration cycles. To tackle this research domain, here, we explore drowsiness detection based on EEG signals' spatiotemporal image encoding representations in the form of either recurrence plots or gramian angular fields for deep convolutional neural network (CNN) classification. Results comparing both techniques using a public dataset of 27 subjects show a superior balanced accuracy of up to 75.87% for leave-one-out cross-validation, using both techniques, against works in the literature, demonstrating the possibility to pursue cross-subject zero calibration design.

Changes in hemodynamics, renal blood flow and urine output during continuous renal replacement therapies.

Continuous renal replacement therapies (CRRT) affect hemodynamics and urine output. Some theories suggest a reduced renal blood flow as the cause of the decreased urine output, but the exact mechanisms remain unclear. A prospective experimental study was carried out in 32 piglets (2-3 months old) in order to compare the impact of CRRT on hemodynamics, renal perfusion, urine output and renal function in healthy animals and in those with non-oliguric acute kidney injury (AKI). CRRT was started according to our clinical protocol, with an initial blood flow of 20 ml/min, with 10 ml/min increases every minute until a goal flow of 5 ml/kg/min. Heart rate, blood pressure, central venous pressure, cardiac output, renal blood flow and urine output were registered at baseline and during the first 6 h of CRRT. Blood and urine samples were drawn at baseline and after 2 and 6 h of therapy. Blood pressure, cardiac index and urine output significantly decreased after starting CRRT in all piglets. Renal blood flow, however, steadily increased throughout the study. Cisplatin piglets had lower cardiac index, higher vascular resistance, lower renal blood flow and lower urine output than control piglets. Plasma levels of ADH and urine levels of aquaporin-2 were lower, whereas kidney injury biomarkers were higher in the cisplatin group of piglets. According to our findings, a reduced renal blood flow doesn't seem to be the cause of the decrease in urine output after starting CRRT.

Multidisciplinary management of liver metastases in patients with colorectal cancer: a consensus of SEOM, AEC, SEOR, SERVEI, and SEMNIM.

Colorectal cancer (CRC) has the second-highest tumor incidence and is a leading cause of death by cancer. Nearly 20% of patients with CRC will have metastases at the time of diagnosis, and more than 50% of patients with CRC develop metastatic disease during the course of their disease. A group of experts from the Spanish Society of Medical Oncology, the Spanish Association of Surgeons, the Spanish Society of Radiation Oncology, the Spanish Society of Vascular and Interventional Radiology, and the Spanish Society of Nuclear Medicine and Molecular Imaging met to discuss and provide a multidisciplinary consensus on the management of liver metastases in patients with CRC. The group defined the different scenarios in which the disease can present: fit or unfit patients with resectable liver metastases, patients with potential resectable liver metastases, and patients with unresectable liver metastases. Within each scenario, the different strategies and therapeutic approaches are discussed.

[The assessment of sedation in the critically ill child on mechanical ventilation during tracheal suction]. / Valoración de la sedación en el niño crítico con ventilación mecánica durante la aspiración endotraqueal.

OBJECTIVES: To compare the changes in clinical sedation scales, bispectral index (BIS) and physiological variables occurring during tracheal suction in critically ill children. DESIGN: Prospective, observational study in critically ill children on mechanical ventilation. BIS value, heart rate (HR), systolic blood pressure (SPB), diastolic blood pressure (DBP), modified Ramsay sedation scale score and the dose of sedative drugs were recorded before and 3 minutes after every tracheal suction. RESULTS: A total of 83 tracheal suctions were analyzed from 46 children, 1 month to 15 years of age. Most of the children (92%) were receiving continuous infusions of fentanyl and midazolam, and 45.7% of them were receiving vecuronium. The increase in BIS, SPB and DBP values were small but statistically significant (BIS, from 51.8 to 57.3; SBP, from 92.9 to 103.1 mmHg; DBP, from 51.8 to 58.9 mmHg). There was poor correlation between the BIS, HR, SBP and DBP values before and after suction. A total of 87% of patients maintained the same Ramsay score values. CONCLUSIONS: Tracheal suction produces a slight increase in the BIS and the BP in critically ill children who are receiving sedation by continuous infusion. Most children with adequate sedation do not need any other drugs before the tracheal suction. Physiological variables have no correlation with sedation scales or BIS values during the tracheal suction.

Detection of Stressful Situations Using GSR While Driving a BCI-controlled Wheelchair.

This paper analyzes the galvanic skin response (GSR) recorded from healthy and motor disabled people while steering a robotic wheelchair (RobChair ISR-UC prototype), to infer whether GSR can help in the recognition of stressful situations. Seven healthy individuals and six individuals with motor disabilities were asked to drive the RobChair by means of a brain-computer interface in indoor office environments, including complex scenarios such as passing narrow doors, avoiding obstacles, and with situations of unexpected trajectories of the wheelchair (controlled by an operator without users knowledge). All these driving situations can trigger emotional arousals such as anxiety and stress. A method called feature-based peak detection (FBPD) was proposed for automatic detection of skin conductance response (SCR) which proved to be very effective compared to the state-of-the-art methods. We found that SCR was elicited in 100% of the occurrences of collisions (lateral scrapings) and 94% of unexpected trajectories.

Double ErrP Detection for Automatic Error Correction in an ERP-Based BCI Speller.

Brain-computer interface (BCI) is a useful device for people with severe motor disabilities. However, due to its low speed and low reliability, BCI still has a very limited application in daily real-world tasks. This paper proposes a P300-based BCI speller combined with a double error-related potential (ErrP) detection to automatically correct erroneous decisions. This novel approach introduces a second error detection to infer whether wrong automatic correction also elicits a second ErrP. Thus, two single-trial responses, instead of one, contribute to the final selection, improving the reliability of error detection. Moreover, to increase error detection, the evoked potential detected as target by the P300 classifier is combined with the evoked error potential at a feature-level. Discriminable error and positive potentials (response to correct feedback) were clearly identified. The proposed approach was tested on nine healthy participants and one tetraplegic participant. The online average accuracy for the first and second ErrPs were 88.4% and 84.8%, respectively. With automatic correction, we achieved an improvement around 5% achieving 89.9% in spelling accuracy for an effective 2.92 symbols/min. The proposed approach revealed that double ErrP detection can improve the reliability and speed of BCI systems.

Effectiveness of the I2AO2 interdisciplinary programme led by nurses on metabolic syndrome and cardiovascular risk: a randomized, controlled trial.

Objective To evaluate the effectiveness of an interdisciplinary programme led by nurses in relation to metabolic syndrome (MS) and cardiovascular risk (CVR). Methods This randomized, controlled, clinical trial included 74 patients diagnosed with MS (experimental group [EG], n = 37; control group [CG], n = 37). The intervention consisted of a 12-month interdisciplinary programme (pre-test, 6 months of intervention, 12 months of intervention, and 1-year follow-up post-intervention) coordinated by nursing. Results We found a progressive and significant reduction for all clinical, biochemical, and anthropometric parameters analysed at different time points. In the EG, remission of MS by 48.1% in the short term was observed (83.8% in the medium term) and maintained at 1 year post-intervention. In the CG, the prevalence of MS increased by 2.7% from the initial evaluation to study completion. A similar trend was observed for CVR. In the EG, 100% of subjects had a moderate-low risk of CVR at 1 year post-intervention, whereas the CG had CVR in all categories. Conclusion An interdisciplinary, nurse-led programme improves participants' metabolic and cardiovascular health, while maintaining long-term effects. Our findings suggest an important role of the professional nurse as a nexus between the patient, different professionals, and the community.

[Renal infarction and kidney rupture: complication of a massive cocaine intoxication in an intestinal carrier]. / Infarto y rotura renales: complicación de intoxicación masiva por cocaína en un portador intestinal.

Major complications derived from the use of cocaine have been described, alter nasal or intravenous administration of the drug. These complications are related to vascular spasm and secondary organ damage. We present the case of an intestinal cocaine packer--in slang, "mule"--, who suffered massive absorption of the drug, resulting n bowel, liver and renal ischemia. This situation, previously undescribe in the literature, ended in kidney rupture. An attempt of embolization, was unsatisfactory, and nephrectomy was finally required. The patient recovered uneventfully, with progressive renal functional improvement. This case, albeit quite exceptional, is illustrative of several of the renal actions of cocaine, and reveals the effects of absorption of cocaine at the intestinal level.

[Abdominal aneurism screening in Primary Care]. / Despistaje de aneurisma de aorta abdominal en Atención Primaria.

OBJECTIVES: To obtain the percentage of abdominal aortic aneurism (AAA) determined in men between 65-74 years old in a health centre using ultrasound, and to describe the distribution of risk factors in the whole sample and in patients with aneurism, as well as determining how many AAA are confirmed at the hospital and those cases of uncertain diagnosis. PATIENTS AND METHOD: A cross-sectional study conducted on patients included from September 2014 to February 2015. From a total of 212 randomised patients, a clinical interview and abdominal ultrasound were performed on 115 men, aged 65 to 74, telephone-recruited from a total of 171 that fulfilled inclusion criteria. RESULTS: An infra-renal AAA was found in 2.6% of the sample (95% CI 0.54-7.4). Just over half (51.3%) of the sample had arterial hypertension, and 76.1% were smokers or former smokers. The 3 AAA found, one of which had an initial doubtful diagnosis, were confirmed by the Hospital Universitario Fundación Jiménez Díaz. There were no losses. All of the patients with AAA were active smokers and had at least one other risk factor. CONCLUSION: The percentage of infra-renal AAA in the sample was lower than expected, but higher than the percentage found in other studies that did not consider smoking in the inclusion criteria.

Importance Weighted Import Vector Machine for Unsupervised Domain Adaptation.

In real-world applications, the assumption of independent and identical distribution is no longer consistent. To alleviate the significant mismatch between source and target domains, importance weighting import vector machine, which is an adaptive classifier, is proposed. This adaptive probabilistic classification method, which is sparse and computationally efficient, can be used for unsupervised domain adaptation (DA). The effectiveness of the proposed approach is demonstrated via a toy problem, and a real-world cross-domain object recognition task. Even though the sparseness, the proposed method outperforms the state-of-the-art in both unsupervised and semisupervised DA scenarios. We also introduce a reliable importance weighted cross validation (RIWCV), which is an improvement of importance weighted cross validation, for parameter and model selection. The RIWCV avoid falling down in local minimum, by selecting a more reliable combination of the parameters instead of the best parameters.

Is Hydrogen Breath Test with Lactulose Feasible for Measuring Gastrocecal Transit in Critically Ill Children? Pilot Study about Modification of the Technique.

Introduction. Gastrocecal transit time (GCTT) can be measured by exhaled hydrogen after lactulose intake (lactulose-eH2 test). The objectives were to assess whether it is possible to carry out this test in critically ill children with and without mechanical ventilation (MV) and to analyze whether the results are consistent with clinical findings. Methods. Patients admitted to the Pediatric Intensive Care Unit (PICU) for more than 3 days were included. Those with gastrointestinal disease prior to admission were excluded. A modified technique to obtain eH2 from the ventilator tubes was performed. Results. Sixteen patients (37.5% boys) with a median age of 19 (5-86.5) months were included. Five patients (31.2%) were breathing spontaneously but lactulose-eH2 test could not be performed while it could be performed successfully in the 11 patients with MV. Seven patients (63.3%) did not show an eH2 peak. The other 4 showed a median time of 130 min (78.7-278.7 min) from lactulose intake to a 10 ppm eH2 peak. Children with an eH2 peak had intestinal movements earlier [6.5 (1.5-38.5) versus 44 (24-72) hours p = 0.545]. Conclusion. Although the designed adaption is useful for collecting breath samples, lactulose-eH2 test may not be useful for measuring GCTT in critically ill children.

Pure visual imagery as a potential approach to achieve three classes of control for implementation of BCI in non-motor disorders.

OBJECTIVE: The achievement of multiple instances of control with the same type of mental strategy represents a way to improve flexibility of brain-computer interface (BCI) systems. Here we test the hypothesis that pure visual motion imagery of an external actuator can be used as a tool to achieve three classes of electroencephalographic (EEG) based control, which might be useful in attention disorders. APPROACH: We hypothesize that different numbers of imagined motion alternations lead to distinctive signals, as predicted by distinct motion patterns. Accordingly, a distinct number of alternating sensory/perceptual signals would lead to distinct neural responses as previously demonstrated using functional magnetic resonance imaging (fMRI). We anticipate that differential modulations should also be observed in the EEG domain. EEG recordings were obtained from twelve participants using three imagery tasks: imagery of a static dot, imagery of a dot with two opposing motions in the vertical axis (two motion directions) and imagery of a dot with four opposing motions in vertical or horizontal axes (four directions). The data were analysed offline. MAIN RESULTS: An increase of alpha-band power was found in frontal and central channels as a result of visual motion imagery tasks when compared with static dot imagery, in contrast with the expected posterior alpha decreases found during simple visual stimulation. The successful classification and discrimination between the three imagery tasks confirmed that three different classes of control based on visual motion imagery can be achieved. The classification approach was based on a support vector machine (SVM) and on the alpha-band relative spectral power of a small group of six frontal and central channels. Patterns of alpha activity, as captured by single-trial SVM closely reflected imagery properties, in particular the number of imagined motion alternations. SIGNIFICANCE: We found a new mental task based on visual motion imagery with potential for the implementation of multiclass (3) BCIs. Our results are consistent with the notion that frontal alpha synchronization is related with high internal processing demands, changing with the number of alternation levels during imagery. Together, these findings suggest the feasibility of pure visual motion imagery tasks as a strategy to achieve multiclass control systems with potential for BCI and in particular, neurofeedback applications in non-motor (attentional) disorders.

Roux-en-Y Gastric Bypass.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) is considered the gold standard for gastric bypass, displaying better results for metabolic disorders than other surgical procedures over the long term. The aim of this study was to determine the effects of bariatric surgery, in particular the RYGB technique, on metabolic syndrome (MS) and other biochemical parameters implicit in the comorbid conditions associated with obesity, as well as to explore the influence of this surgical procedure on psychiatric comorbidity in the study population. METHOD: An observational retrospective cohort study based on 146 clinical records of patients having undergone RYGB between January 1, 2011, and January 1, 2014, was performed. Data related to metabolic and psychiatric comorbidity were gathered at three stages: prior to surgery and at 3 and 9 months following surgery. RESULTS: There was a progressive and statistically significant reduction of all biochemical parameters analyzed at 3 and 9 months following surgery except high-density lipoprotein cholesterol, which significantly increased (beneficial) in value. These changes imply a remission of >90% for all metabolic disorders and the consequent tendency toward a reduction in prescribed pharmacological treatments, with MS found in only one subject at 9 months. There was, however, no significant reduction in pharmacological treatments for psychiatric comorbidities. CONCLUSION: Findings suggest that RYGB is an effective treatment for MS and other metabolic disorders but not for psychiatric comorbidities accompanying MS.

Assessment of pain in critically ill children. Is cutaneous conductance a reliable tool?

PURPOSE: The purpose of this study is to assess the usefulness and accuracy of skin conductance (SC) as a tool to evaluate the level of sedation and pain in pediatric critical patients during painful procedures and to compare it with hemodynamic variables, clinical scales, and bispectral index (BIS). MATERIALS AND METHODS: This is a prospective observational study in 61 critical children undergoing invasive procedures. Hemodynamic data (heart rate and arterial blood pressure), clinical scales punctuation (Ramsay, COMFORT, and numeric rating pain scales), BIS, and the number of fluctuations of SC per second were collected before, during, and at the end of the procedure. RESULTS: The mean age of the patients was 42.9 (range, 1 month to 16 years). Seventy-two point six percent were postcardiac surgery patients. Nonmuscle-relaxed patients showed a moderate increase in heart rate (P = .02), numeric rating pain scales (P = .03), and Ramsay scale (P = .002). The number of fluctuations of SC per second increased significantly during the procedure (basal, 0.1; maneuver, 0.2; P = .015), but it never reached the level considered as pain or stress nor did it precede clinical scales or BIS. None of the variables studied showed a significant change during the procedure in muscle-relaxed patients. CONCLUSIONS: Skin conductance was not found to be more sensitive or faster than clinical scales for the assessment of pain or stress in critical children undergoing painful procedures. Skin conductance was not useful in muscle-relaxed children.

[Hemodynamic effects of intravenous omeprazole in critically ill children]. / Efectos hemodinámicos del omeprazol por vía intravenosa en niños en estado crítico.

INTRODUCTION: Critical patients usually have hemodynamic disturbances which may become worse by the administration of some drugs. Omeprazole is a drug used in the prophylaxis of the gastrointestinal bleeding in these patients, but its cardiovascular effects are unknown. The objective was to study the hemodynamic changes produced by intravenous omeprazole in critically ill children and to find out if there are differences between two different doses of omeprazole. MATERIAL AND METHODS: A randomized prospective observational study was performed on 37 critically ill children aged from 1 month to 14 years of age who required prophylaxis for gastrointestinal bleeding. Of these, 19 received intravenous omeprazole 0.5mg/kg every 12 hours, and 18 received intravenous omeprazole 1mg/kg every 12 hours. Intravenous omeprazole was administered in 20 minutes by continuous infusion pump. Heart rate, systolic, diastolic and mean arterial blood pressure, central venous pressure and ECG were recorded at baseline, and at 15, 30, 60 and 120 minutes of the infusion. RESULTS: There were no significant changes in the electrocardiogram, heart rate, blood pressure and central venous pressure. No patients required inotropic therapy modification. There were no differences between the two doses of omeprazole. CONCLUSIONS: Intravenous omeprazole administration of 0.5mg/kg and 1mg/kg is a hemodynamically safe drug in critically ill children.