The association between night eating syndrome and GERD symptoms among university students at An-Najah National University in Palestine: a cross-sectional study.

BACKGROUND: Night eating syndrome (NES) is a kind of eating disorder. NES association with gastroesophageal reflux disease (GERD) symptoms among university students is still not fully understood. We aimed to determine the relationship between NES and the presence of GERD symptoms among university students at An-Najah National University in Palestine. METHODS: This study involved undergraduate students from An-Najah National University. The data were collected through online surveys from November to December 2023. The sampling frame involved voluntary sampling, as the data were collected using a structured questionnaire to collect data on sociodemographic variables, medical history, lifestyle habits, nutritional status, GERD risk, and NES. The GERD questionnaire (GerdQ) was used to assess symptoms, while the Arabic version of the validated Night Eating Questionnaire (NEQ) was used to assess night eating. Physical activity was assessed using the short form of the International Physical Activity Questionnaire (SF-IPAQ), and adherence to a Mediterranean diet was assessed using the validated Arabic version of the MEDAS. Both univariate and multivariate analyses were also conducted to assess the study hypotheses. RESULTS: The study involved 554 participants, 59.9% female. A total of 33.4% reported GERD symptoms, with 10.3% having NES. A strong association was observed between GERD and NES and between GERD and physical activity. Night eating syndrome (AOR = 2.84, CI = 1.07-3.19), high physical activity (AOR = 0.473, CI = 1.05-3.19), and non-smoking (AOR = 0.586, CI = 1.27-7.89) were identified as independent predictors of GERD symptoms. CONCLUSION: This study revealed that 33.4% of undergraduate students were at risk of GERD, with night eaters having a greater risk. GERD risk was negatively associated with physical activity level and smoking status. No associations were found between GERD risk and weight status, Mediterranean diet adherence, sociodemographic factors, or sleep disturbances.

In Situ Investigation of Upper Airway Occlusion in Sleep Disordered Breathing Using Ultrasonic Transducer Arrays.

This work presents a novel application of ultrasound for the real-time, non-invasive investigation of occlusion of the upper airway during events of obstructive sleep apnea/hypopnea syndrome. It is hypothesized that ultrasonic pulses applied to the neck during apneic events produce spectral and temporal features that can detect apnea occurrence. Theoretical models of ultrasound propagation and an in vitro test were conducted to test this hypothesis in both transmission and reflection modes. Complete specifications and technical details of the system design and fabrication, which is mounted on each subject's neck, are presented, including the methodology. Nine patients (seven male and two female, mean age of 42 years, with a range of 25 to 56 years, and body mass index 37.6 ± 6.6 kg/m2) were recruited for a full night study, which included simultaneous nocturnal polysomnography for the validation of the results. Nine temporal features and four spectral features were extracted from the envelope of the received pulse waveform. These were used to compute 26 metrics to quantify the changes in the ultrasonic waveforms between normal breathing and apneic events. The statistical analysis of the collected ultrasonic data showed that at least two or more of the proposed features could detect apneic events in all subjects. The findings establish the feasibility of the proposed method as a cost-effective and non-invasive OSAHS screening tool.

Performance of disc, conventional and automatic screen filters under rainbow trout fish farm effluent for drip irrigation system.

This study aims to investigate the performance of disc, conventional screen, and automatic screen filters when rainbow trout fish effluent is used for irrigation. The experiments were performed in a fish farm, located in the north-west of Iran. The disc and conventional screen filters were tested at pressures of 150 and 300 kPa, and the automatic screen filter at 200 and 300 kPa. The filtration experiments continued until the backwashing was reached. The results showed that (1) the initial head loss of disc and conventional screen filters was 40 kPa, while for the automatic screen filter was 5 kPa. (2) In the disc filter, with increasing working pressure, the filtered volume significantly (P < 0.05) increased from 9.7 to 14.5 m3 m-2 (10 kPa)-1, but for conventional and automatic screen filters, it was constant at 5.5 and 7.0 m3 m-2 (10 kPa)-1, respectively, and all of them had significant (P < 0.05) differences. (3) In the disc filter, with increasing the working pressure, the filtered volume to reach backwashing significantly (P < 0.01) increased from 80.9 to 104.4 m3 m-2, while in the conventional screen filter increased from 14.1 to 16.4 m3 m-2. This volume at two working pressures was 29.5 m3 m-2 for the automatic screen filter. These volumes were significantly different (P < 0.01) between filters. (4) The mass retention for the disc, conventional, and automatic screen filters were 28.88, 9.11, and 7.72 g min-1 m-2, respectively, and tended to increase at lower working pressures. Based on this index, the difference in the performance of the filters was significant (P < 0.01). (5) Overall, the best performance was for the disc filter, and after that was the automatic screen filters, but the period of time to operate for the filters until backwashing time was less than half an hour, which is not applicable under farm conditions.

Estimation of cerebral blood flow velocity during breath-hold challenge using artificial neural networks.

The effect of untreated Obstructive Sleep Apnoea (OSA) on cerebral haemodynamics and CA impairment is an active field of research interest. A breath-hold challenge is usually used in clinical and research settings to simulate cardiovascular and cerebrovascular changes that mimic OSA events. This work utilises temporal arterial oxygen saturation (SpO2) and photoplethysmography (PPG) signals to estimate the temporal cerebral blood flow velocity (CBFv) waveform. Measurements of CBFv, SpO2, and PPG, were acquired concurrently from volunteers performing two different protocols of breath-hold challenge in the supine position. Past values of the SpO2 and PPG signals were used to estimate the current values of CBFv using different permutations and topologies of supervised learning with shallow artificial neural networks (ANNs). The measurements from one protocol were used to train the ANNs and find the optimum topologies, which in turn were tested using the other protocol. Data collected from 10 normotensive, healthy subjects (four females, age 28.5 ±â€¯6.1 years, Body Mass Index (BMI) 24.0 ±â€¯4.7 kg/m2) were used in this study. The results show that different subjects have different optimum topologies for ANNs, thus indicating the effects of inter-subject variability on ANNs. Successfully reconstructed blind waveforms for the same subject group in the second protocol showed a reasonable accuracy of 60-80% estimation compared to the measured waveforms. HYPOTHESIS: Temporal waveforms for SpO2 and PPG contain adequate information to estimate the temporal CBFv waveform using ANNs. METHODOLOGY: Concurrent measurements of SpO2 and PPG using pulse oximetry from the forehead and CBFv from the middle cerebral artery (MCA) using transcranial Doppler (TCD) were recorded from healthy, normotensive subjects performing a breath-hold challenge. The breath-hold challenge mimicked the cerebrovascular response to apnoea, and was recorded by measuring CBFv in MCA. Two protocols were used, each consisting of five breath-holding manoeuvres and differing in terms of the time between the five successive breath-holds. Using data from one protocol, several permutations of the temporal values of SpO2 and PPG signals were used as inputs to different ANN topologies, in order to train and find the optimum model. The optimum model was evaluated using the data from the other protocol as a blind dataset. RESULTS: Using the first protocol for training, optimum ANN configurations were found to be different for each subject, and accuracy of 75-87% was achieved. When these optimum ANN models were tested using the second protocol as a blind dataset, the accuracy achieved was around 60-80%. CONCLUSIONS: A novel approach employing temporal records of SpO2 and PPG can be used to estimate the CBFv waveform using ANNs with acceptable accuracy. Increases in the size and diversity of the population dataset and the use of features extracted from SpO2 and PPG signals are needed for generalisation of the method and potential future clinical applications.

Quantifying Long QT Syndrome in Obese Sleep Apnea Patients Undergoing Roux-en-Y Gastric Bypass Surgery.

Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS) is sleep-disordered breathing distinguished by repetitive cessation or reduction of airflow due to the collapse or narrowing of the upper airway during sleep with continued respiratory effort. A high level of incidence of OSAHS is correlated with obesity. Both severely obese patients and OSAHS patients manifest Long QT Syndrome (LQTS). It is reported that most obese patients undergoing weight reduction surgery positively reverse symptoms of LQST. Also, severely obese OSAHS undergoing the same surgery report alleviation of OSAHS symptoms. In this study, we presented preliminary results of the changes in QT and QTc intervals for obese OSAHS patients undergoing Roux-en-Y Gastric Bypass (RYGB) surgery and had their weight reduced, and were treated from OSAHS post-RYGB surgery. We developed an algorithm to detect the different waveforms in the ECG signal and calculated QT and QTc intervals. Results comparing the changes in the QT and QTc pre- and post-RYGB surgery for four apneic subjects (Aged 37.0 ± 8.9 years, Pre-RYGB BMI 51.7 ± 10.1 kg/m2, Post-RYGB BMI 35.6 ± 7.9 kg/m2) were contrasted with a control group of 3 non-apneic subjects (Aged 32.7 ± 7.0 years, Pre-RYGB BMI 50.8 ± 11.8 kg/m2, Post-RYGB BMI 31.6 ± 2.9 kg/m2) who underwent the same surgery. The results suggest that although the RYGB surgery is successful in weight loss and OSAHS symptoms reduction, apneic patients may continue to have non-reversible LQTS despite long-term weight reduction.

Phantom study evaluating detection of simulated upper airway occlusion using piezoelectric ultrasound transducers.

Obstructive sleep apnea/hypopnea syndrome (OSAHS) is characterized by repetitive narrowing or full collapse of the upper airway concomitant with continued respiratory effort during sleep lasting 10s or more. OSAHS is the most prevalent form of sleep-disordered breathing, affecting more than 17% of the middle-aged U.S. POPULATION: Hence, many individuals need to be tested for having OSAHS. Currently, detection of airway occlusion due to OSAHS is achieved by indirect measurements, often requiring multiple sensor types, such as a flow transducer combined with chest and abdomen plethysmography. The need for the use of multiple sensors in the current OSAHS detection systems adds to the cost and complexity of the current systems and associated procedures. Development of a simple sensor system that allows direct detection of airway occlusion is advantageous, as it simplifies detection of OSAHS and paves the way for home diagnosis of OSAHS. The utilization of ultrasonic transducers is attractive, as it is non-invasive and non-ionizing. We present a new ultrasound sensing system for direct detection of the occlusion in the upper airway in OSAHS patients during sleep. The system takes into consideration the constraints arising from the location of probing and the acoustic requirements for transducers. The physiological and theoretical backgrounds are presented for using ultrasonic pulses to detect the presence and degree of occlusion in the airway. The proposed methodology for creating an anthropomorphically-correct neck and airway phantoms to test the hypothesis and the results of the tests are presented. HYPOTHESIS: An ultrasonic signal transmitted through or reflected from an open airway will have different features compared to those associated with a partially or fully occluded airway. METHODOLOGY: A system, comprising a phantom model of the airway and neck with the approximate anatomical-correct dimensions and acoustic properties of the airway, is designed and built. It allows simulating fully open airway as well as hypopnea and apnea events. Further, it facilitates probing using multiple ultrasonic frequencies and transducer configurations for use with different neck sizes. Ultrasound waves are generated using a piezoelectric source to the model of the airway and received by piezoelectric receivers on the opposite side. Energy, the area under the curve, and the peak value of the received signal, are used to detect the airway occlusion. RESULTS: The amount of reflected ultrasonic energy from the phantom model of the airway back to the transmitting transducer reduces as the airway model occlusion increases. Also, transmitted signal through the airway model increases as the amount occlusion of the airway model increases. CONCLUSIONS: The results of this study support the hypothesis that it is feasible to use ultrasonic pulses to detect partial and full upper airway occlusion.

Algorithm for automatic angles measurement and screening for Developmental Dysplasia of the Hip (DDH).

Developmental Dysplasia of the Hip (DDH) is a medical term represent the hip joint instability that appear mainly in infants. The examination for this condition can be done by ultrasound for children under 6 months old and by X-ray for children over 6 months old. Physician's assessment is based on certain angles derived from those images, namely the Acetabular Angle, and the Center Edge Angle. In this paper, we are presenting a novel, fully automatic algorithm for measuring the diagnostic angles of DDH from the X-ray images. Our algorithm consists of Automatic segmentation and extraction of anatomical landmarks from X-ray images. Both of Acetabular angle and Center edge angle are automatically calculated. The analysis included X-ray images for 16 children recruited for the purposed of this study. The automatically acquired angles accuracy for Acetabular Angle was around 85%, and an absolute deviation of 3.4°±3.3° compared to the physician's manually calculated angle. The results of this method are very promising for the future development of an automatic method for screening X-ray images DDH that complement and aid the physicians' manual methods.

An investigation of simultaneous variations in cerebral blood flow velocity and arterial blood pressure during sleep apnea.

Obstructive Sleep Apnea (OSA) is a major sleep disorder with a prevalence of about 15 % among US adult population and can lead to cardiovascular diseases and stroke. In this study, we have investigated the OSA-induced concurrent rise in cerebral blood flow velocity and blood pressure in 5 positively diagnosed sleep apnea subjects. The subject population had a mean AHI of 57.94±25.73 and BMI of 33.66±7.27 kg/m(2). The results of this preliminary study yielded a relatively high correlation between rise in blood pressure and rise in cerebral blood flow velocity during apnea episodes (r=0.61±0.16) compared to normal breathing (r=0.28±0.26). These findings suggest that cerebral autoregulation may be less effective during apnea episodes.

Upper airway occlusion detection using a novel ultrasound technique.

Obstructive sleep apnea/hypopnea Syndrome (OSAHS) is the most common form of Sleep Disordered Breathing (SDB) and it is estimated to affect approximately 15% of US adult population. In this paper, we report on the results of in vivo experiments of an ultrasonic device for the non-invasive detection of obstructive sleep apnea/hypopnea (OSAH). A description of the ultrasonic system used is presented, followed by the results of a full night sleep study. The findings show a significant difference in the spectral features extracted from the received ultrasonic waveform during apneic breathing, compared to the hyperventilation that follows. Therefore, the findings indicate the feasibility of developing an ultrasonic detection device for low cost diagnosis of SDB.

Relation between arterial blood pressure and cerebral blood flow velocity in simulated sleep apnea.

Obstructive Sleep Apnea (OSA) is one of the most common breathing disorder, affecting approximately 27% of U.S. adults. Limited data have suggested that OSA causes cerebral autoregulation impairment, thus being an important risk factor to stroke. The objective of this paper is to investigate and measure the relation between arterial blood pressure (BP) and cerebral blood flow velocity (CBFV) in simulated apnea. Sixteen healthy subjects (9 male, 7 female) of 29±4.89 yrs age and body mass index of 24.07±4.84 kg/m(2) participated in the study. Four protocols were used; sitting 30 seconds, 90 s, and supine 30 s and 90 s. Our results showed that systolic BP and peak CBFV were correlated with average r=0.672 +0.265. Also, CBFV exhibited a significantly higher percent rise than BP. Thus, our findings suggest that cerebral autoregulation may be impaired during apnea episodes.

In vivo characterization of ultrasonic transducers for the detection of airway occlusion in Sleep Disordered Breathing.

Obstructive Sleep Apnea/Hypopnea Syndrome (OSAHS) is the most common form of Sleep Disordered Breathing (SDB) and it is estimated to affect approximately 15% of US adult population. Various methods have been proposed for the development of inexpensive screening methods to detect SDB to reduce the need for costly nocturnal polysomnography (NPSG). In this paper, a description of the ultrasonic transducer design and characterization is presented, followed by the results of a full night sleep study. The findings show a significant difference in the temporal features extracted from the received ultrasonic waveform during apneic breathing, compared to the hyperventilation that follows. Therefore, the findings indicate the feasibility of developing an ultrasonic detection device for low cost diagnosis of SDB.

Concurrent variations of cerebral blood flow and arterial blood pressure in simulated sleep apnea.

Obstructive Sleep Apnea (OSA) is one of the most common sleep disordered breathing which affects about 15 % of US adult population. OSA is considered to be an important risk factor for the development of cardiac dysfunction and stroke. In this paper, we present the initial results of our investigation of the relationship between arterial blood pressure and cerebral blood flow velocity in simulated apnea. Sixteen healthy subjects (9 male, 7 female) of 29 ± 4.89 yrs age and body mass index of 24.07 ± 4.84 kg/m(2) participated in the study. Our findings indicate that cerebral blood flow velocity variations has a relatively high correlation to changes in blood pressure during simulated apnea (r = 0.74 ± 0.06), suggesting that cerebral autoregulation may not compensate for the pressure changes during apnea.

Detection of airway occlusion in simulated obstructive sleep apnea/hypopnea using ultrasound: an in vitro study.

Obstructive sleep apnea/hypopnea Syndrome (OSAHS) is the most common form of Sleep Disordered Breathing (SDB) and it is estimated to affect approximately 6% of US adult population. Various methods have been proposed for the development of inexpensive screening methods to detect SDB to reduce the need for costly nocturnal polysomnography (NPSG). By using the existing air in the airway as an ultrasonic contrast agent, we propose a method to examine the narrowing or occlusion of the airway associated with OSAHS events. We describe here an in vitro study that approximates the anatomical and acoustic characteristics of the airway and neck. In this experiment, we simulate the fully open airway as well as apnea and hypopnea events. These in vitro studies results show significant differences in the ultrasonic signals acquired from the open airway model versus those from the model depicting apnea and hypopnea events. Therefore, the findings provide a foundation for development of an ultrasound system to detect SDB in vivo.

Introducing and evaluating MorphoDent, a Web-based learning program in dental morphology.

MorphoDent, a computer-assisted learning program designed to teach the anatomy of the adult dentition, was introduced into the curriculum of dentistry at the University of Saarland in Homburg, Germany. Thirty-six second-year students of the School of Dentistry were introduced to morphoDent alongside the traditional lectures of dental anatomy. Questionnaires that evaluated the students' perceptions of virtual learning as well as aspects of the functionality of the program educational objectives were developed and distributed to the students. Online tests were performed and compared with a traditional examination. All questionnaires were returned. A wide variety of aspects dealing the pedagogic implications of e-learning were evaluated by the students, with the overall result being that students are aware of the needed hardware and technical skills and expect the quality of their studies to improve by implementation of e-learning. All sophomores except one felt that morphoDent had helped them in learning dental morphology and reported enjoying the virtual anatomical examination. One-third reported technical difficulties in operating the program. The average exam score was 2.53 (SD: 0.66) for the traditional and 2.23 (SD: 0.59) for the online dental anatomy test. Students expressed their positive attitude towards e-learning in general and indicated that the use of photorealistic 3D models of human teeth supported the process of individual learning of dental anatomy. The online test could be rated as a good option for students' self-performance rating.

Sleep disordered breathing detection using heart rate variability and R-peak envelope spectrogram.

We report that combining the interbeat heart rate as measured by the RR interval (RR) and R-peak envelope (RPE) derived from R-peak of ECG waveform may significantly improve the detection of sleep disordered breathing (SDB) from single lead ECG recording. The method uses textural features extracted from normalized gray-level cooccurrence matrices of the time frequency plots of HRV or RPE sequences. An optimum subset of textural features is selected for classification of the records. A multi-layer perceptron (MLP) serves as a classifier. To evaluate the performance of the proposed method, single Lead ECG recordings from 7 normal subjects and 7 obstructive sleep apnea patients were used. With 500 randomized Monte-Carlo simulations, the average training sensitivity, specificity and accuracy were 100.0%, 99.9%, and 99.9%, respectively. The mean testing sensitivity, specificity and accuracy were 99.0%, 96.7%, and 97.8%, respectively.

Reconstruction of reflectance data using an interpolation technique.

A linear interpolation method is applied for reconstruction of reflectance spectra of Munsell as well as ColorChecker SG color chips from the corresponding colorimetric values under a given set of viewing conditions. Hence, different types of lookup tables (LUTs) have been created to connect the colorimetric and spectrophotometeric data as the source and destination spaces in this approach. To optimize the algorithm, different color spaces and light sources have been used to build different types of LUTs. The effects of applied color datasets as well as employed color spaces are investigated. Results of recovery are evaluated by the mean and the maximum color difference values under other sets of standard light sources. The mean and the maximum values of root mean square (RMS) error between the reconstructed and the actual spectra are also calculated. Since the speed of reflectance reconstruction is a key point in the LUT algorithm, the processing time spent for interpolation of spectral data has also been measured for each model. Finally, the performance of the suggested interpolation technique is compared with that of the common principal component analysis method. According to the results, using the CIEXYZ tristimulus values as a source space shows priority over the CIELAB color space. Besides, the colorimetric position of a desired sample is a key point that indicates the success of the approach. In fact, because of the nature of the interpolation technique, the colorimetric position of the desired samples should be located inside the color gamut of available samples in the dataset. The resultant spectra that have been reconstructed by this technique show considerable improvement in terms of RMS error between the actual and the reconstructed reflectance spectra as well as CIELAB color differences under the other light source in comparison with those obtained from the standard PCA technique.

Cross correlation and scatter plots of the heart rate variability and R-peak Envelope as features in the detection of obstructive sleep apnea.

Interbeat heart rate as measured by the RR interval (RR) and R-Peak Envelope (RPE) are two signals that can be extracted from an Electrocardiogram (ECG) with relative ease and high reliability. RR and RPE have been shown to carry markers for detecting sleep disordered breathing (SDB). In this pilot study, we explore the cross correlation of RR and RPE in normal and SDB patients. Nocturnal ECG from 7 normal subjects and 7 SDB patients were used to obtain RR and RPE. The results revealed that the cross correlation of RR and RPE signals is significantly different between normal subjects and SDB patients (p 2x10(-6)). Furthermore, a new scatter plot of RR vs. RPE was developed. Optimum features from the RR vs. RPE scatter plot were extracted and used as input to a multilayer perceptron (MLP) classifier to distinguish between normal and SDB subjects, The detection sensitivity, specificity and accuracy for the training data set were 95.0%, 100.0%, and 97.5%, respectively; and for the test data were 76.6%, 93.2%, and 84.7%, respectively.

A method to detect obstructive sleep apnea using neural network classification of time-frequency plots of the heart rate variability.

This paper presents a new method of analyzing time-frequency plots of heart rate variability to detect sleep disordered breathing from nocturnal ECG. Data is collected from 12 normal subjects (7 males, 5 females; age 46+/-9.38 years, AHI 3.75+/-3.11) and 14 apneic subjects (8 males, 6 females; age 50.28+/-9.60 years; AHI 31.21+/-23.89). The proposed algorithm uses textural features extracted from normalized gray-level co-occurrence matrices (NGLCM) of images generated by short-time discrete Fourier transform (STDFT) of the HRV. Using feature selection, seventeen features extracted from 10 different NGLCMs representing four characteristically different gray-level images are used as inputs to a three-layer Multi-Layer Perceptron (MLP) classifier. After a 1000 randomized Monte-Carlo simulations, the mean training classification sensitivity, specificity and accuracy are 99.00%, 93.42%, and 96.42%, respectively. The mean testing classification sensitivity, specificity and accuracy are 94.42%, 85.40%, and 90.16%, respectively.

A new method to detect obstructive sleep apnea using fuzzy classification of time-frequency plots of the heart rate variability.

This paper presents a new method of analyzing time frequency plots of heart rate variability to detect sleep disordered breathing from nocturnal ECG. Data is collected from 12 normal subjects (7 males, 5 females; age 46 +/- 9.38 years, AHI 3.75 +/- 3.11) and 14 apneic subjects (8 males, 6 females; age 50.28 +/- 9.60 years; AHI 31.21 +/- 23.89). The proposed algorithm uses textural features extracted from normalized gray-level co-occurrence matrices (NGLCM) of images generated by short-time discrete Fourier transform (STDFT) of the HRV. Thirty selected features extracted from 10 different NGLCMs representing four characteristically different gray-level images are used as inputs to 10 Fuzzy Logic Systems (FLS) Classifiers. Each FLS is trained and their outputs are combined using a weighed majority rule method. The mean training detection sensitivity, specificity and accuracy are 86.87%, 71.72%, and 79.29%, respectively. The mean testing detection sensitivity, specificity and accuracy are 83.22%, 68.54%, and 75.88%, respectively.

La técnica del bloqueo caudal vs anestesia general para la piloromiotomía y el comportamiento de las catecolaminas en el postoperatorio / The technique of caudal block vs general anesthesia for the pylorius miotomy and the behavior of the catecholamines in the postoperatorie

Objeto: Demostrar que el bloqueo caudal produce una recuperación más rápida y segura, además eficiente control del dolor postoperatorio. Sitio: Centro de atención terciaria. Diseño: estudio prospectivo, controlado, abierto. Pacientes: El estudio se realizó de Enero a Noviembre de 1993. Se incluyeron 34 pacientes en el estudio, los cuales fueron divididos en dos grupos, mediante una randomización simple al azar y secuencial. Al primer grupo de 20 pacientes se le colocó bloqueo caudal, asistidos con ligera anestesia general (Grupo I). Al segundo grupo de pacietes control se le aplicó anestesia general usual con halotano (Grupo II). Se valoró edad, talla, peso, estado nutricional, alteraciones electrolíticas, dosis del anestésico, duración de la cirugía, cambios de la temperatura del paciente durante la cirugía y duración de la recuperación con un patrón respiratorio propio y efectivo. El nivel de analgesia postoperatorio fue medido, mediante la determinación del grado de stress, a través de la cuantificación de catecolaminas libres o conjugadas en orinas. Resultados: Se incluyeron 30 pacientes, 16 en el grupo I y 14 en el grupo II. En el grupo I la medida de nivel de catecolaminas (en pg/mg de creatinina) a las 4,6 y 12 horas fué 185 (DS 336), comprado con el grupo II donde los niveles fueron 126 (DS 110), 382 (DS 737) y 908 (DS 1160). En todos los tiempos la diferencia no fue estadísticamente significativa (p=0.4). Sin embargo al comparar la diferencia en los niveles de catecolaminas a las 12 horas con respecto a las 4 horas, éste fué significativamente mayor grupo II; 782 (DS 423) pg/mg creatinina vs 488 (DS 1247) respectivamente (p=0.04). Conclusiones: Los pacientes del grupo I tuvieron una mejor analgesia postoperatoria que los pacientes del grupo II, requiriendo una cantidad significativamente menor de analgésicos adicionales. Palabras clave: bloqueo caudal, anestesia general, piloromiotomía