[Failure mode effect analysis for safety improvement in the automatic drug dispensing systems]. / Aplicación de un análisis modal de fallos y efectos para la mejora de la seguridad en la utilización de los sistemas automatizados de dispensación de medicamentos.

OBJECTIVE: To identify the risks in automated dispensing cabinet use in order to improve routine procedure safety. METHODS: We used the Failure Mode Effect Analysis (FMEA) methodology. A multidisciplinary team identified potential failure modes of the procedure through a brainstorming session. We assessed the impact associated with each failure mode with the Risk Priority Number (RPN), which involves three variables: occurrence, severity, and detectability. Improvement measures were established for failure modes with RPN>100 considered critical. The final RPN (theoretical) that would result from the proposed measures was also calculated. RESULTS: The process was divided into five sub-processes: automatic delivery of order replacement, to prepare order in a pyramidal cart, transport of the pyramidal cart from the pharmacy service to the automated dispensing cabinet, replacement of the automated dispensing cabinet by the pharmacy technician and dispensing/returning by nursing staff. Twenty-two failure modes, with 25 cases and with varying effects (severity 2-8) were evaluated. The sub-process with more failure modes with NPR>100 was dispensing/returning by nursing staff. CONCLUSIONS: The FMEA methodology was a useful tool when applied to automated dispensing cabinet system use. The implementation of improvement actions significantly reduced the risk.

[Comparison of optic nerve head measurements obtained with the slit lamp and with CSLO]. / Comparación de las medidas de la papila obtenidas con biomicroscopia y con oftalmoscopia de láser confocal.

PURPOSE: To evaluate the accuracy of disk size and cup/disk ratio (C/D) estimation by measuring the vertical diameter and cup/disk ratio at the slit lamp. METHODS: Two hundred and thirty eight eyes of 185 people, 82 glaucomas and 156 normal subjects were included. All underwent slit lamp examination, tonometry, optic nerve photographs, scanning laser tomography (HRT) and standard perimetry (Humphrey). Correlation between slit lamp measurements (vertical diameter and C/D ratio) and HRT parameters was evaluated. RESULTS: There is a significant correlation between the disk diameter measured at the slit lamp and the disk area measured with HRT (Pearson Test, r: 0.52, p<0.001). Additionally, there is significant correlation between the semi-quantitative estimation of C/D ratio at the slit lamp and the C/D area ratio from the HRT (r: 0.83, p<0.001). CONCLUSION: Measuring the vertical diameter and the C/D ratio at the slit lamp is a useful method for estimating the real disk area and C/D ratio. It is highly recommended that disk size be estimated when attempting to interpret clinical findings in the optic nerve head.

Comparación de las medidas de la papila obtenidas con biomicroscopia y con oftalmoscopia de láser confoncal / Comparison of Optic Nerve Head Mesurements Obtained with the Slit Lamp and with CSLO

Objetivo: Evaluar la precisión de la estimación del tamaño de la papila y el índice excavación/papila (E/P) mediante la medición del diámetro vertical y la excavación en la lámpara de hendidura. Método: Se incluyeron 238 ojos de 185 personas, 82 con glaucoma y 156 normales. Todos fueron examinados con lámpara de hendidura, tonometría, fotografías del nervio óptico, tomografía con láser confocal (HRT) y perimetría estándar (Humphrey). Se evaluó la correlación entre el diámetro vertical de la papila y el índice excavación/papila (E/P) medidos en la lámpara de hendidura (lente de 90 o 78 dioptrías) y varios parámetros objetivos obtenidos con el HRT. Resultados: Existe una correlación estadísticamente significativa entre el diámetro papilar estimado mediante biomicroscopía y el área de la papila calculado por el HRT (Test de Pearson, r: 0,52, p<0,001). Asimismo se observó una correlación estadísticamente significativa entre la estimación semicuantitativa del índice E/P obtenido por biomicroscopia y el parámetro área de la excavación/área de la papila calculado por el HRT (r: 0,83; p<0,001). Conclusión: La medida del diámetro vertical y del índice E/P en la lámpara de hendidura es una buena estimación del área de la papila y del cociente área excavación/área de la papila. Se recomienda la valoración del tamaño de la papila a la hora de interpretar los hallazgos clínicos observados en el nervio óptico(AU)

Purpose: To evaluate the accuracy of disk size and cup/disk ratio (C/D) estimation by measuring the vertical diameter and cup/disk ratio at the slit lamp. Methods: Two hundred and thirty eight eyes of 185 people, 82 glaucomas and 156 normal subjects were included. All underwent slit lamp examination, tonometry, optic nerve photographs, scanning laser tomography (HRT) and standard perimetry (Humphrey). Correlation between slit lamp measurements (vertical diameter and C/D ratio) and HRT parameters was evaluated. Results: There is a significant correlation between the disk diameter measured at the slit lamp and the disk area measured with HRT (Pearson Test, r: 0.52, p<0.001). Additionally, there is significant correlation between the semi-quantitative estimation of C/D ratio at the slit lamp and the C/D area ratio from the HRT (r: 0.83, p<0.001). Conclusion: Measuring the vertical diameter and the C/D ratio at the slit lamp is a useful method for estimating the real disk area and C/D ratio. It is highly recommended that disk size be estimated when attempting to interpret clinical findings in the optic nerve head(AU)

[Comparative study of two portable tonometers: Tono-Pen XL and Perkins]. / Estudio comparativo de dos tonómetros portátiles: Tono-Pen XL y Perkins.

PURPOSE: To evaluate the reproducibility of two portable tonometers and to compare the intraocular pressure (IOP) measurements obtained with both instruments taking into account the level of experience of the examiner with this technique. METHOD: Cross-sectional study. IOP was measured in 35 eyes of 35 normal subjects and 20 eyes of 20 ocular hypertensive patients with Perkins aplanation tonometer and Tono-Pen XL digital tonometer. Five measurements were made with Perkins (by an ophthalmologist) and 10 with Tono-Pen (5 by an ophthalmologist and 5 by a general practitioner). RESULTS: Considering the sample as a whole there was no statistically significant difference, and there was a significant correlation between the mean measurements obtained with Perkins tonometer and Tono-Pen and between the mean obtained by doctors with and without previous tonometric experience (p<0.001, ANOVA). Variability of Tono-Pen measurements is greater than the Perkins measurements and it is considerable in both cases (coefficient of variation 7-9%). Tono-Pen measurements tend to show a greater variability in hypertensive subjects, and tend to underestimate high IOP when compared with Perkins measurements. Tono-Pen identified IOP > or =21 mmHg with a sensitivity of 40% and a specificity of 94-97%. CONCLUSION: Tono-Pen allows measurement of IOP to personal with no tonometric experience. There is a strong correlation between measurements obtained with both tonometers. Tono-Pen shows a tendency to underestimate high IOP and offers low sensitivity in detecting IOP greater than 21 mmHg.

Estudio comparativo de dos tonómetros portátiles: Tono-Pen XL y Perkins / Comparative study of two portable tonometers: Tono-Pen XL and Perkins

Objetivo: Valorar la reproducibilidad de dos tonómetros portátiles y comparar las medidas de presión intraocular (PIO) obtenidas con ambos instrumentos y por facultativos con y sin formación tonométrica previa. Método: Estudio transversal. Se midió la PIO de 35 ojos de 35 sujetos normales y de 20 ojos de 20 sujetos hipertensos oculares con el tonómetro de aplanación Perkins y el tonómetro digital Tono-Pen XL. Se realizaron 5 medidas con Perkins (oftalmólogo) y 10 con Tono-Pen (5 por el oftalmólogo y 5 por el médico general).Resultados: Considerando las medidas medias y todos los sujet os en conjunto no se observaron diferencias significativas, y sí una correlación estadísticamente significativa entre las medidas medias obtenidas con ambos tonómetros y entre facultativos (p<0,001, ANOVA). La variabilidad de las medidas realizadas con el Tono-Pen es mayor que la conseguida con el Perkins y en ambos casos es considerable (coeficiente de variación 7 por ciento a 9 por ciento). En los hipertensos oculares existe una tendencia a una mayor variabilidad de las medidas realizadas con el Tono-Pen, así como a una infravaloración de las PIO elevadas al compararlas con el Perkins. El Tono-Pen identificó PIO = 21 mmHg con una sensibilidad del 40 por ciento y una especificidad del 94-97 por ciento. Conclusión: El Tono-Pen permite medir la PIO a facultativos sin experiencia tonométrica previa. Se observó una elevada correlación entre las medidas realizadas con ambos tonómetros y por cada facultativo. El Tono-Pen presenta una tendencia a infravalorar las PIO elevadas y una baja sensibilidad para detectar PIO superiores a 21 mmHg (AU)

Purpose: To evaluate the reproducibility of two portable tonometers and to compare the intraocular pressure (IOP) measurements obtained with both instruments taking into account the level of experience of the examiner with this technique. Method: Cross-sectional study. IOP was measured in 35 eyes of 35 normal subjects and 20 eyes of 20 ocular hypertensive patients with Perkins aplanation tonometer and Tono-Pen XL digital tonometer. Five measurements were made with Perkins (by an ophthalmologist) and 10 with Tono-Pen (5 by an ophthalmologist and 5 by an general practitioner). Results: Considering the sample as a whole there was no statistically significant difference, and there was a significant correlation between the mean measurements obtained with Perkins tonometer and Tono-Pen and between the mean obtained by doctors with and without previous tonometric experience (p< 0.001, ANOVA). Variability of Tono-Pen measurements is greater than the Perkins measurements and it is considerable in both cases (coefficient of variation 7-9%). Tono-Pen measurements tend to show a greater variability in hypertensive subjects, and tend to underestimate high IOP when compared with Perkins measurements. Tono-Pen identified IOP ≥ 21 mmHg with a sensitivity of 40% and a specificity of 94-97%. Conclusion: Tono-Pen allows measurement of IOP to personal with no tonometric experience. There is a strong correlation between measurements obtained with both tonometers. Tono-Pen shows a tendency to underestimate high IOP and offers low sensitivity in detecting IOP greater than 21 mmHg (AU)

A comparison of no-flow and low-flow ischemia in the rat heart: an energetic study.

Heat production under no-flow ischemia (ISCH) and under hypoperfusion (HYP) conditions was measured in single isovolumetric contractions of perfused rat ventricles at 25 degrees C. Resting heat production (Hr) and resting pressure decreased when the perfusion rate was reduced from 6 to 1.5 mL min(-1) or lower flows (HYP) and by ISCH. Maximal developed pressure (P) decreased to 29% and 20% of control by HYP at 0.8 mL min(-1) and ISCH, respectively. The tension-independent heat (TIH) fraction attributed to Ca2+-binding, measured during single contractions, decreased under HYP with an increase in the ratio between the maximum relaxation rate and P (-P/P ratio). The TIH fractions (attributed to Ca2+ binding and Ca2+ removal processes) decreased under ISCH. The long duration TIH fraction associated with Ca2+-dependent mitochondrial activity disappeared at flow rates of 1.5 mL min(-1) or lower. The ratio between the tension-dependent energy release and P was decreased by ISCH but not by HYP, indicating that under ISCH there was an improvement in contractile economy, but this was not modified by HYP. Overall, the results indicate that no-flow and low-flow ischemias are energetically different models. While the contractile failure under HYP seems to be related to a decrease in myofilament Ca2+ sensitivity, under ISCH it appears to be related to decreased cytosolic Ca2+ availability combined with a more noticeable effect on a fraction of energy that has been attributed to mitochondrial activity. Furthermore, mechanical and energetic responses of both models (i.e., ISCH and HYP) found in the present work were not the same as those previously observed in severe hypoxia so that all these models should not be used indistinctly.

The heart extrasystole: an energetic approach.

The consequences of an extrasystole (ES) on cardiac muscle's energetics and Ca2+ homeostasis were investigated in the beating heart. The fraction of heat release related to pressure development (pressure dependent) and pressure-independent heat release were measured during isovolumic contractions in arterially perfused rat ventricle. The heat release by a contraction showed two pressure-independent components (H1 and H2) of short evolution and a pressure-dependent component (H3). The additional heat released by ES was decomposed into one pressure-independent (H'2) and one pressure-dependent (H'3) component with time courses similar to those of control components H2 and H3. ES also induced the potentiation of pressure development (P) and heat release during the postextrasystolic (PES) beat. The slope of the linear relationship between pressure-dependent heat and pressure maintenance was similar in control, ES, and PES contractions (0.08 +/- 0.01, 0.10 +/- 0.02, and 0.08 +/- 0.01 mJ. g-1. mmHg-1. s-1, respectively). The potentiation of H2 (heat component related with Ca2+ removal processes) in PES was equal to H'2 at 0.3, 0.5, 1, and 2 mM Ca2+, suggesting that the extra amount of Ca2+ mobilized during ES was recycled in PES. Pretreatment with 1 mM caffeine to deplete sarcoplasmic reticulum Ca2+ content inhibited both the mechanical and energetic potentiation of PES. However, the heat released and the pressure developed during ES were not changed by sarcoplasmic reticulum depletion. The results suggest that 1) the source of Ca2+ for ES would be entirely extracellular, 2) the Ca2+ entered during ES is accumulated in the sarcoplasmic reticulum, and 3) the Ca2+ stored by the sarcoplasmic reticulum during ES induces an increased contribution of this organelle during PES compared with the normal contraction.

[Maternal nutrition effect on fetus development and pregnant women's health]. / Efecto de la nutrición materna sobre el desarrollo del feto y la salud de la gestante.

A review is made of the main prenatal growth stages and the way they are influenced by social and biological factors pointing out the role of maternal nutrition before and during pregnancy. It is discussed the available evidence on the relation of maternal nutrition and fetal growth through clinical and epidemiological studies performed in animal and humans, analyzing the causal mechanisms of this association, including the role of placenta. Some clinical useful indicators that allow to evaluate maternal nutrition throughout gestation are presented. Emphasis is made on the impact of protein-energy malnutrition as well as on some specific deficiencies, particularly iron and folic acid. At last, the synergic effect of infection and malnutrition on low birth weight and prematurity is analyzed.

Energetics of heart muscle contraction under high K perfusion: verapamil and Ca effects.

Tension-dependent (TDH) and tension-independent heat (TIH) release were measured during single isovolumetric contractions in the arterially perfused rat ventricle. Under perfusion with 7 mM K-0.5 mM Ca, TDH showed only one component (H3), whereas TIH could be divided into two components (H1 and H2) of short evolution (similar to the classically identified activation heat) and one component (H4) of long duration (dependent on mitochondrial respiration). Under 25 mM K, TIH components (i.e., H1, H2, and H4) increased with the increase in extracellular Ca concentration ([Ca]o) from 0.5 to 4 mM, and H3 correlated with pressure at all [Ca]o, with regression parameters similar to those observed under 7 mM K. Under 25 mM K-2 mM Ca, peak pressure development (P), H1, H2, and H3, plotted against the number of beats under 0.4 microM verapamil, exponentially decreased, but H4 decreased to 5.5 +/- 2.9% in the first contraction and remained constant thereafter. Under hypoxia, P, H1, H2, and H3 progressively decreased for about six contractions, but H4 was not detectable from the second contraction. The results suggest that increasing extracellular K concentration decreases contractile economy mainly by increasing energy expenditure related to a Ca-dependent (verapamil-sensitive) mitochondrial activity that is not related to force generation.

[Usefulness of ultrasonographic markers in chromosomal abnormalities]. / Utilidad de los marcadores ultrasonográficos de cromosomopatía.

During a 3 and 1/2 years, 132 pregnancies were diagnosed as having a wide variety of congenital abnormalities. A high resolution ultrasound and multidisciplinary approach was used. In 95 cases fetal karyotyping was made. In this group the incidence of chromosomal abnormalities diagnosed during the period and phenotypic expression of the different types of chromosomal abnormalities was investigated. 29 abnormal karyotypes were found; 11 trisomy 18, 7 in monosomy X, 4 in trisomy 21, 3 in trisomy 13, 1 with tetraploidy (92XXYY), 1 Turner mosaic (45XO 68% 46XY 32%), 2 inversions of choromosome 9. Of the total abnormal chromosomal diagnosed during the period (N = 57), this group represented 49.2%, compared to 5 to 15% found in other risk groups. 224 congenital abnormalities were found. 43 (19%) isolated, and 181 (81%) associated. Of the 224 congenital abnormalities diagnosed, 80 (36%) were associated with chromosomal abnormalities. The most associated markers were duodenal atresia, heart defect, microcephaly, enlarged posterior fossa, and cystic hygromata. A specific markers pattern was found for each aneuploidy; heart defects for trisomy 18, holoprosencephaly and faciel cleft for trisomy 13, and cystic hygromata for monosomy X. It was concluded that the ultasound can be the most useful method to select the group of pregnant women with a higher risk of abnormal karyotype.

The energetics of the quiescent heart muscle: high potassium cardioplegic solution and the influence of calcium and hypoxia on the rat heart.

Heart basal metabolism has been classically studied as the energy expenditure of those processes unrelated to mechanical activity and often measured by rendering the heart inactive using cardioplegic solutions (usually by increasing extracellular K concentration ([Kle]). In arterially perfused rat heart (at 25 degrees C), raising [K]e from 7 to 25 mM at a constant extracellular Ca concentration ([Ca]e) (0.5 mM), induced an increase in resting heat production (Hr) from 4.1 +/- 0.3 to 5.1 +/- 0.3 mol. wt g-1. Under 25 mM K additional increase in [Ca]e further increased Hr to 6.0 +/- 0.4, 7.0 +/- 0.4 and 8.3 +/- 0.9 mol. wt g-1 for 1, 2 and 4 mM Ca, respectively. While under 7 mM K perfusion Hr was not affected by 4 microM verapamil, under 25 mM K and 2 mM Ca 0.4 microM verapamil induced a decrease in Hr (-1.6 +/- 0.2 mol. wt g-1, n = 5, P < 0.001). Caffeine increased Hr under 0.5 mM Ca and 7 mM K perfusion (+0.32 +/- 0.06 and +1.19 +/- 0.25 mol. wt g-1 for 1 and 5 mM caffeine respectively), but under 25 mM K conditions Hr was not affected by caffeine 2 mM. Severe hypoxia decreased Hr under both 7 and 25 mM K (3.7 +/- 0.5 to 2.7 +/- 0.4 mol. wt g-1 and 7.0 +/- 0.4 to 2.2 +/- 0.5 mol. wt g-1, respectively) suggesting that the increased Hr associated with the verapamil sensitive fraction of heat released is associated to a mitochondrial mechanism. Therefore, the use of high [K]e overestimates basal values by increasing a verapamil sensitive fraction of the energy released. In addition, high [K]e modifies a caffeine sensitive energy component probably due to a depletion of caffeine-dependent Ca stores.

Tension-dependent and tension-independent energy components of heart contraction.

Heat production and isovolumetric pressure development (P) were measured simultaneously in the arterially perfused rat ventricle. The time course of the calorimetric signal that follows a contraction could be decomposed into four components of energy released. Three of these components (H1, H2, and H4) were pressure independent, only H3 correlated with either P or the pressure-time integral (PtI) (r > 0.78, n = 36, P < 0.01). The dimensionless slope of the regression of H3 on P was 0.24 (an index of muscle economy) and the absence of O2 (N2 replacement) decreased it to 0.178 suggesting that 26% of H3 is related to oxidative metabolism. H4 was the most affected by the lack of O2 in the perfusate. It decreased to 16% in the first beat under N2 without change in P or in H1, H2 or H3, and disappeared (1.6 +/- 1.0 mJ.g-1) in the fourth contraction under N2 (while P, H1, H2 and H3 remained over 64% of their control values). H4 was activated during the first 1-3 beats after a quiescent period and remained active for several seconds (even in the absence of subsequent stimulation) as if the basal metabolism had been increased to a new steady level. H1 and H2 were dependent on the extracellular Ca. The magnitudes of both H1 (1.8 +/- 0.2 mJ.g-1) and H2 (2.7 +/- 0.2 mJ.g-1) were similar to those reported for the fast and slow components of activation heat in skeletal muscle. If twin stimuli are applied (200 ms apart), additional energy is released (+3.0 +/- 0.3 mJ.g-1) that can be decomposed in two components similar to those identified as H2 and H3. The magnitude of H1, its absence in the twin contraction and its Ca dependency suggest an association with Ca-binding processes (mainly Troponin C). The presence of an H2 component during the twin contraction, its magnitude and Ca dependence gives support to a relationship between H2 and Ca removal processes.

[The role of vibroacoustic stimulation in antenatal fetal assessment]. / Papel de la estimulación vibroacústica en la evaluación fetal anteparto.

The value of antepartum fetal heart rate testing has been debated in the last few years. According to several research works, the fetal sleeping periods lead to falsely nonreactive tests. These increase the risk and costs of obstetric care. A randomized prospective clinical trial was undertaken in high risk pregnancies to compare the standard nonstress test with the fetal vibroacoustic stimulation. Acoustic stimulation during 5 seconds with a 75 Hz frequency and 74 dB intensity device was applied to the patients in the study group. Nonreactive results were obtained in 11% of the control group and 3.4% in the study group (z = 2.07, p = 0.00116). A reduction of 5 minutes in the length of the test was observed in the study group. Fetal acoustic stimulation should be considered an alternative to improve the efficacy of nonstress testing, by reducing falsely nonreactive tests results and the time it takes to perform them.

Influence of extracellular potassium on energetics of resting heart muscle.

The effects of various extracellular K concentrations ([K]e) on energy expenditure and their relationship to ionic exchange mechanisms under quiescent conditions were investigated in the arterially perfused rat heart. The increase in [K]e (from 6 to 12, 24, or 50 mM K) leads to a rapid increase (results are given per gram dry weight) in resting energy expenditure (+5.9 +/- 0.9, +13.6 +/- 1.1, and +30.0 +/- 2.0 mW/g, respectively) followed by a slow decrease toward a new steady rate of heat production but higher (+2.8 +/- 0.7, +6.3 +/- 0.6, and +10.5 +/- 1.1 mW/g) than that observed under control conditions (21.1 +/- 0.7 mW/g). The increase in [K]e from 6 to 50 mM also induced an increase in K influx (calculated from 86Rb uptake and efflux experiments) of approximately 0.25 mumol.g-1.s-1. If this increased K influx is driven by the Na-K pump, an increase in steady resting heat production of approximately 10 mW/g would be expected. This represents 95% of the increase in steady heat production measured for 50 mM K intervention. The simultaneous increase in the cellular Ca flux (+0.1 mumol.g-1.min-1) can only explain (if driven by the sarcolemmal Ca pump) less than 1% of the steady increase in heat production. The work also shows that the initial, transitory increase in resting heat production induced by increasing [K]e is caffeine sensitive and may be at least partially attributable to a transitory enhanced activity of the sarcoplasmic reticulum.

Caffeine effects on heart muscle energetics: species differences.

The effects of caffeine (1mM) on energy expenditure and mechanical parameters in rat and toad perfused heart ventricles were examined at various stimulation frequencies. While in rat muscles caffeine significantly depressed developed tension and maximal rates of contraction and relaxation at all frequencies tested, in toad ventricle a slight positive inotropic effect was observed. Even though caffeine did not alter total contraction time in both preparations, in the rat ventricle the last part of relaxation was prolonged. In rat ventricle in the presence of caffeine, the ratios between active heat production per beat and either developed tension or tension time integral increased at all frequencies tested (+303 +/- 47 microJ.mN-1 x g-1 and +1.21 +/- 0.13 mJ.mN-1 x s-1 x g-1 respectively) indicating a decrease in contractile economy. In toad ventricle no changes on these ratios were observed. The fact that only in rat ventricle caffeine decreased muscle economy suggests that caffeine affects a system that is active in rat ventricle but it is not operative in toad ventricle. This gives support to the hypothesis that if in rat ventricle SR-Ca pump (1 ATP hydrolyzed/2 Ca transported) is inhibited by caffeine cytosolic Ca would have to be removed by alternative mechanisms such as Na-Ca exchanger or sarcolemmal Ca pump both with a higher rate of ATP hydrolysis (1 ATP hydrolyzed/Ca transported) with the consequent decrease in muscle economy. Resting heat production was increased by caffeine in both preparations and the magnitude of the increment (+3.0 +/- 0.6 mW.g-1 and +0.75 +/- 0.21 mW.g-1 for rat and toad ventricle respectively) also correlates with the different degree of SR activity in both species.

Caffeine effects on heart muscle energetics: species differences.

The effects of caffeine (1mM) on energy expenditure and mechanical parameters in rat and toad perfused heart ventricles were examined at various stimulation frequencies. While in rat muscles caffeine significantly depressed developed tension and maximal rates of contraction and relaxation at all frequencies tested, in toad ventricle a slight positive inotropic effect was observed. Even though caffeine did not alter total contraction time in both preparations, in the rat ventricle the last part of relaxation was prolonged. In rat ventricle in the presence of caffeine, the ratios between active heat production per beat and either developed tension or tension time integral increased at all frequencies tested (+303 +/- 47 microJ.mN-1 x g-1 and +1.21 +/- 0.13 mJ.mN-1 x s-1 x g-1 respectively) indicating a decrease in contractile economy. In toad ventricle no changes on these ratios were observed. The fact that only in rat ventricle caffeine decreased muscle economy suggests that caffeine affects a system that is active in rat ventricle but it is not operative in toad ventricle. This gives support to the hypothesis that if in rat ventricle SR-Ca pump (1 ATP hydrolyzed/2 Ca transported) is inhibited by caffeine cytosolic Ca would have to be removed by alternative mechanisms such as Na-Ca exchanger or sarcolemmal Ca pump both with a higher rate of ATP hydrolysis (1 ATP hydrolyzed/Ca transported) with the consequent decrease in muscle economy. Resting heat production was increased by caffeine in both preparations and the magnitude of the increment (+3.0 +/- 0.6 mW.g-1 and +0.75 +/- 0.21 mW.g-1 for rat and toad ventricle respectively) also correlates with the different degree of SR activity in both species.

Caffeine effects on heart muscle energetics: species differences.

The effects of caffeine (1mM) on energy expenditure and mechanical parameters in rat and toad perfused heart ventricles were examined at various stimulation frequencies. While in rat muscles caffeine significantly depressed developed tension and maximal rates of contraction and relaxation at all frequencies tested, in toad ventricle a slight positive inotropic effect was observed. Even though caffeine did not alter total contraction time in both preparations, in the rat ventricle the last part of relaxation was prolonged. In rat ventricle in the presence of caffeine, the ratios between active heat production per beat and either developed tension or tension time integral increased at all frequencies tested (+303 +/- 47 microJ.mN-1 x g-1 and +1.21 +/- 0.13 mJ.mN-1 x s-1 x g-1 respectively) indicating a decrease in contractile economy. In toad ventricle no changes on these ratios were observed. The fact that only in rat ventricle caffeine decreased muscle economy suggests that caffeine affects a system that is active in rat ventricle but it is not operative in toad ventricle. This gives support to the hypothesis that if in rat ventricle SR-Ca pump (1 ATP hydrolyzed/2 Ca transported) is inhibited by caffeine cytosolic Ca would have to be removed by alternative mechanisms such as Na-Ca exchanger or sarcolemmal Ca pump both with a higher rate of ATP hydrolysis (1 ATP hydrolyzed/Ca transported) with the consequent decrease in muscle economy. Resting heat production was increased by caffeine in both preparations and the magnitude of the increment (+3.0 +/- 0.6 mW.g-1 and +0.75 +/- 0.21 mW.g-1 for rat and toad ventricle respectively) also correlates with the different degree of SR activity in both species.

[Usefulness of intraperitoneal transfusion under direct ultrasound guidance]. / Utilidad de la transfusión intraperitoneal bajo guía ultrasonográfica directa.

Experience with intraperitoneal blood transfusion, using ultrasonographic guide, in 24 patients with severe isoimmunization to Rh factor, is reported. A total of 57 procedures, were done from 24 weeks of gestation. In 66.6% two or more transfusions were done in the same product. There were 71% of alive newborns and in 29% of the cases it was not possible to improve perinatal survival. The analysis of these results were correlated with antecedents: presence of hydrops, gestational age at the time of resolving pregnancy, and main disease status. The usefulness of intraperitoneal transfusion, is commented upon, and new perspectives, as intravascular transfusion in cases with severe hydrops, are considered.

Mechanisms underlying post-rest potentiation in isolated left rat atria.

In the isolated rat left atria the influence of rest intervals on the force developed by the first post rest beat (PRB) was studied. Under control conditions the force developed by the PRB increased (respect to previous steady state at 0.5 Hz) with the increase of the rest interval until 20 sec of pause and decreased with longer intervals. In the presence of caffeine (1 or 4 mM plus high [Ca]0) there was a monotonous fall of the PRB as a function of the rest interval. When extracellular calcium was replaced by Sr the tension developed by PRB vs. rest interval curve rose with a slope lower than the control one and reached the peak at 60 sec. At saturation levels of [Ca]0 the PRB tension development did not vary up to 20 sec pause but the decreasing phase observed after 20 sec of rest interval was still present. At 0.5 mM [Ca]0 the response was similar to control curve. The results in the presence of caffeine and strontium suggest that, in rat atria, the rest potentiation appears to be dependent on the release of calcium from intracellular stores (sarcoplasmic reticulum). This is consistent with the hypothesis proposing that longer resting periods provide a longer interval for the transfer of Ca from uptake to release sites in the sarcoplasmic reticulum.

Mechanisms underlying post-rest potentiation in isolated left rat atria.

In the isolated rat left atria the influence of rest intervals on the force developed by the first post rest beat (PRB) was studied. Under control conditions the force developed by the PRB increased (respect to previous steady state at 0.5 Hz) with the increase of the rest interval until 20 sec of pause and decreased with longer intervals. In the presence of caffeine (1 or 4 mM plus high [Ca]0) there was a monotonous fall of the PRB as a function of the rest interval. When extracellular calcium was replaced by Sr the tension developed by PRB vs. rest interval curve rose with a slope lower than the control one and reached the peak at 60 sec. At saturation levels of [Ca]0 the PRB tension development did not vary up to 20 sec pause but the decreasing phase observed after 20 sec of rest interval was still present. At 0.5 mM [Ca]0 the response was similar to control curve. The results in the presence of caffeine and strontium suggest that, in rat atria, the rest potentiation appears to be dependent on the release of calcium from intracellular stores (sarcoplasmic reticulum). This is consistent with the hypothesis proposing that longer resting periods provide a longer interval for the transfer of Ca from uptake to release sites in the sarcoplasmic reticulum.