Apnéia de deglutiçäo no homem adulto / Swallowing apnea in adult man

Com a finalidade de caracterizar a apnéia de deglutiçao foram analisados traçados de correlaçoes de fluxo ventilatório/deglutiçao de 66 indivíduos, sendo cinco laringectomizados totais. Foram estudadas 1916 correlaçoes, sendo 109 nos laringectomizados e 1807 em nao-laringectomizados. Os traçados foram produzidos por um transdutor piezo-elétrico e por um termistor, existentes em equipamento de manometria computadorizada. As observaçoes deste estudo permitiram concluir que: 1. a apnéia de deglutiçao é um fenômeno reflexo cuja via de produçao é distinta da via daquela apnéia, que pode ser observada quando do estímulo direto de receptores laríngeos; 2. a apnéia de deglutiçao independe da laringe e, conseqüentemente, do fechamento da rima glótica para a sua instalaçao; 3. a apnéia de deglutiçao e o fechamento da rima glótica, que se processam em concomitância, sao açoes inderdependentes, mas distintas dentro do conjunto de açoes capazes de proteger as vias aéreas; e 4. embora haja a possibilidade de a apnéia de deglutiçao ser produzida em outros momentos do ciclo respiratório, esta se processou, na quase totalidade das observaçoes, nas fases final da expiraçao e inicial da inspiraçao, quase sempre seguidas por expiraçoes complementar. Parece lícito supor que o menor volume pulmonar, nesses momentos, seja condicionante de importância no mecanismo da apnéia de deglutiçao.

Ventilacion mecanica no invasiva como tratamiento de la neumonia severa en un paciente con serologia HIV positiva / Non-invasive mechanical ventilation as treatment for severe pneumonia in an HIV positive patient

Paciente de 27 años, HIV+ que ingresa en insuficiencia respiratoria por probable neumonía por Pneumocystis carinii (NPC). Presentaba disnea severa, uso de músculos accesorios y frecuencia respiratoria 44 por minuto. El a/AO(2) era 0.35. Se aplicó BiPAP durante 12 horas. Al retirarla el a/AO(2) era O.42, con alivio de la disnea, disminución de la frecuencia respiratoria (25 por min) y sin uso de músculos accesorios. No se observaron complicaciones. Al momento del alta el a/AO(2) era 0.68. La aplicación de CPAP ha sido comunicada en pacientes con PCP, pero no la BiPAP. Nuestro paciente mostró claras evidencias de mejoría sugiriendo que la BiPAP en PCP es una alternativa útil que debería ser incorporada al manejo de estos pacientes.

Swallowing-induced cardio-respiratory responses in man

Swallowing transiently increases heart rate. One of the authors developed pronounced bradycardia while breath holding, particularly after an expiration. The objective, therefore, was to study his cardiac responses during swallowing as pronounced bradycardia developed. When, after a maximum inspiration [supine], the heart rate slowly fell below 50 beats min-1 well-defined P waves [lead II] disappeared. By swallowing 6 times on command after the P waves disappeared his heart rate increased immediately [68 +/- I beats min-1 n=6]. P waves with similar morphology to those pro-swallowing were recorded 0.7 +/- 0.1 s [n=6] after the first swallow. He continued breath holding after swallowing. P waves again disappeared although at faster heart rates [57 +/- I beats min-1; n=6]. Furthermore, well-defined P waves were observed after the second disappearance at heart rates within the range 30-40 beats min-1 Small amplitude P waves continued to be recorded from lead I with P wave disappearance in lead II, suggesting a pacemaker shift although not to the av node. Autonomic nerves can shift the dominant pacemaker within the sa node. The present report indicates that increased vagal tone may be rapidly reversed by swallowing

Nivel crítico de oxígeno disponible en pacientes graves con falla pulmonar aguda / Critical level of oxygen delivery in critically ill patients with acute pulmonary failure

Introducción: La función celular normal depende de un aporte adecuado de O2 para satisfacer sus necesidades metabólicas. Objetivo. Encontrar el nivel crítico de O2 disponible (DO2) en pacientes graves con falla pulmonar aguda en la ciudad de México. Pacientes y métodos. Estudiamos retrospectivamente 25 pacientes con falla pulmonar aguda (14 mujeres, 11 hombres, edad media 46 ñ 177 años) en una UCI multidisciplinaria de un hopsital de tercer nivel de atención. Se efectuaron 140 mediciones de 20 variables hemodinámicas. El análisis estadístico incluyó t de Student y análisis de regresión lineal simple. Resultados. El nivel crítico de DO2 fue 386 ñ 149 mL/min.m² cuando el consumo de oxígeno (VO2) fue 80 ñ 22.4 mL/min.m², a un nivel mayor a 110 mL/min.m² de VO2, la DO2 fue e 530 ñ 179 mL/min.m². Hubo una correlación baja entre VO2 y DO2 (r² = 0.2952, p = 0.0424) pero la correlación entre DO2 y oxígeno residual (RO2) a un nivel de VO2 menor a 110 mL/min.m² fue alta (r² = 0.9187, p< 0.001). La DO2 se puede expresar en función de RO2 así: DO2 = 1.24 x RO2 (r² = 0.9235, p < 0.001). Conclusión. Un decremento del VO2 a un nivel de DO2 menor a 386 mL/min.m² sugiere deprivación tisular de O2 y utilización inadecuada del oxígeno residual

Study of oxygen saturation, breathing pattern and arrhythmias in patients of interstitial lung disease during sleep.

Twenty patients of interstitial lung disease (ILD) and same number of healthy adults were selected to monitor arterial hemoglobin oxygen saturation (SaO2) breathing pattern and arrhythmias during sleep. The maximum fall in SaO2 during sleep was 13.1% (10-16%) in ILD patients as compared to 4.8% (3-6%) in controls and the difference was significant (p < 0.005). The ILD patients spent 16.9% of mean total sleep time (TST) below 85% SaO2 and 0.7% of mean TST below 80% SaO2 whereas none of the healthy subjects had SaO2 below 90% during sleep. These patients had more disturbed sleep than controls. Abnormally high breathing frequency demonstrated by ILD patients while awake, was not altered during sleep. Both tidal volume (VT) and minute ventilation (Vmin) decreased by 6.6% and 11.5%, respectively in ILD patients during sleep though it was not significant (p > 0.25) statistically. The respiratory drive was declined during sleep in ILD patients. The percent of tidal volume contributed by rib cage (% RC) lessened during sleep in all the subjects. The ratio of the total excursion of the rib cage and abdomen during inspiration without considering the direction of movement, divided by tidal volume (TCD/VT) revealed asynchronous breathing in ILD patients during sleep. Arrhythmias were found in 6 (30%) of ILD patients and 4 (20%) of control subjects. Observed apnea-hypopnea did not qualify for sleep apnea syndrome in any case.

Respiratory function during warm-up exercise in athletes.

The theme of the present study is to stress the importance of duration of warm-up exercise on respiratory functions in athletes. Significant improvements in athletic performance was achieved due to warm-up exercise owing to increase in blood flow, muscle and core temperature. The optimum intensity and duration are required to bring about the desired warm-up. A close examination on respiratory functions and its relationship with exercise has not been studied extensively. The present investigation is to explore the various respiratory functions in relation to the intensity and duration in preadolescent athletes before and after warm-up exercise. The results show a significant increase in vital capacity after 25 min and a significant reduction in FEV0.5, FEF75% and FEF25-75% after 45 min of warm-up exercise. The results suggest that a warm-up exercise of short duration (25 min) and mild intensity was beneficial than long duration (45 min) and intense exercise. Although the performance of athletes was not directly measured during exercise, these data demonstrate the benefit of warm-up.

Función respiratoria y su repercusión estomatognática y orgánica / Respiratory function and its stomatognathic and organic repercussion

La funcionalidad respiratoria es extremadamente importante para el desarrollo del complejo nasomaxilar, además del desarrollo sistémico. Una respiración alterada y, en particular, una respiración de tipo bucal, tiene consecuencias específicas sobre todo el organismo. Estas han sido objeto de estudio en nuestra investigación, que se ha desarrollado con el auxilio de tres diferentes métodos rinomanométricos (rinomanometría anterior activa, rinomanometría posterior activa y rinomanometría posterior bilateral simultánea). Los resultados indican que los respiradores bucales tienen valores de resistencia nasal por encima de la media y que éstas disminuyen después del test dinámico de esfuerzo en los sujetos con patologías obstructivas de las primeras vías aéreas con base vasomotora. Se ha observado que una respiración no fisiológica está asociada a signos típicos (faciales, adenoidea, disturbios digestivos, alteraciones a nivel de columna y tórax) y una mayor susceptibilidad a las infecciones de las vías aéreas altas (amigdalitis, que pueden involucrar al oído medio (otitis) por la proximidad anatómica o llegar más profundamente (neumonías). Sería beneficioso examinar precozmente a los pacientes y someterlos a un plan de tratamiento adecuado que evitaría o haría menos grave la aparición de alteraciones irreversibles

Reanimación cardiopulmonar cerebral / Cerebral cardiopulmonary resuscitation

The guidelines, recomendations and complications of cardiopulmonary and brain resuscitation are analized

Effect of graded head-up tilt on parasympathetic reactivity.

Thirteen healthy subjects were tested for parasympathetic reactivity during head-up tilt and reversal of the tilt. Head-up tilt (70 degrees) resulted in significant increase in baseline heart rate and diastolic blood pressure. Head-up tilt also led to increased parasympathetic reactivity as measured by Valsalva manoeuvre and hand grip test. Heart rate response to deep breathing test did not change. The reversal of the tilt led to returning of heart responses to original values. Responses indicate towards enhanced parasympathetic reactivity during head-up tilt position.

Influence of respiration on human sympathetic skin response.

Sympathetic skin response (SSR) is a reflexly elicited potential of the sweat glands, the afferent and efferent fibres of the reflex are cutaneous sensory fibres (if the SSR is elicited by electrical stimulus) and sympathetic sudomotor fibres respectively. Our earlier study indicated that latency, besides duration and amplitude, of SSR of a given normal individual showed significant variations between many trials of stimulation, even in a single sitting. Since deep inspiration is also an effective stimulus to elicite SSR, the present study was conducted to assess the influence of respiration on SSR. Thirty-four healthy students participated in the study. The skin of the forearm of the dominant hand was stimulated by electrical square pulse and SSR was recorded from the ipsilateral hand. SSR was elicited and recorded in each subject during the various phases of respiration, namely, end expiration (EE), end inspiration (EI), mid expiration (ME) and mid inspiration (MI). It was observed that the mean values of SSR latency during these respiratory phases (EE : 1.59, EI: 1.51, ME : 1.55, and MI: 1.56 sec) were similar, indicating that the normal respiration might not be responsible for the observed interstimulation variations in latency in any given individual.

Anestesia em coelhos / Anesthesia in rabbits

O objetivo deste trabalho de revisao foi orientar ao pesquisador nao habituado com técnicas anestésicas, a melhor forma de anestesiar o coelho para permitir um bom desenvolvimento de seu experimento. Atençao foi empreendida para a avaliaçao pré-anestésica, as limitaçoes para o uso do coelho em experimentaçao, particularidades e técnicas para a intubaçao orotraqueal, vias de administraçao dos agentes anestésicos, medicaçao pré-anestésica, monitorizaçao anestésica, agentes e técnicas para anestesia com agentes injetáveis e inalatórios, e alguns cuidados pós-anestesia que devem ser tomados.

Cambios espirométricos después de la colecistectomía laparoscópica y la colecistectomía abierta / Spirometric changes after laparoscopic cholecystectomy vs. open cholecystectomy

Objetivo. Evaluar los cambios espirométricos en el posoperatorio inmediato en un grupo de pacientes a los que se les efectuó colecistectomía por laparoscopia y comparar los resultados con otro grupo operado a cielo abierto. Diseño. Estudio observacional, prospectivo, transversal y comparativo. Sede. Servicios de Anestesiología y Cirugía General del Hospital Regional "Vicente Guerrero" del IMSS en Acapulco, Gro. Pacientes y métodos. Cuarenta pacientes con diagnóstico de litiasis vesicular los cuales fueron distribuidos en forma aleatoria en dos grupos de veinte cada uno. Al grupo uno se efectuó colecistectomía por laparoscopia al dos celcistectomía abierta con la técnica tradicional. En todos los enfermos se efectuó espirometría antes de la cirugía y un días después de la intervención con un espirómetro modelo flowmate. El método estadístico fue la t de Student. Resultados. La capacidad vital en el grupo uno disminuyó en el postoperatorio un 31.4 por ciento en comparación a la basal y en el grupo dos 57 por ciento (p menor de 0.01). El flujo a mitad de la espiración disminuyó 26.6 por ciento en el grupo uno en comparación al valor preoperatorio y en el grupo dos, 70.8 por ciento (p menor de 0.01). Conclusión. Los cambios espirométricos después de la colecistectomía laparoscópica son de menor cuantía comparado con los que se presentan después de la colecistectomía abierta, con la posibilidad de que se presenten también menos complicaciones pulmonares en el postoperatorio, debiéndose elegir la técnica laparoscópica en pacientes con mayor riesgo anestésico-quirúrgico

Interactions between body temperature regulation and blood acid-base status in anuran amphibians

In vertebrate evolution, the transition from aquatic to terrestrial mode of life was associated with considerable changes in the respiratory system and CO2/pH-sensitive receptors became fundamental. The present review focuses on the combined effects of hypercapnia and body temperature in anuran amphibians, that represent a key group for the transition. Recent studies have indicated that temperature affects the hypercapnic drive to breathe. Conversely, hypercapnia modulates the range of preferred body temperature of amphibians and central (CO2/pH) receptors are likely to be involved.

Is the short-term modulation if heart rate in teleost fish physiologically significant? Assessment by spectral analysis techniques

Heart rate is an important physiological variable in the control of cardiac output, even in fishes, where the importance of stroke volume has been overemphasized. Except for the myxinoids, the fish heart is innervated by cranial nerve X and the nature of this innervation is mainly inhibitory by parasympathetic fibers, although a sympathetic contribution has also been demonstrated. In mammals, cardiac innervation is not only responsible for the control of mean heart rate but it also modulates the beat-to-beat heart rate changes. These beat-to-beat changes are known as heart rate variability (HRV) and appear to be related to fluctuations in respiration and blood pressure. In this paper we demonstrate the link between cardiac innervation and HRV in several species of teleosts because HRV is greatly decreased after vagotomy or atropinization. In contrast, after abolishing the sympathetic influence with propranolol, only slight changes in total HRV are observed, indicating the restricted importance of the adrenergic innervation in determining phasic changes in HRV despite the significant tonic effect which has been demonstrated. Thus, it appears unlikely that the sympathetic influence will be present in any measured spectral component as suggested previously. Furthermore, clear spectral patterns do not always exist and this may be due to the erratic influence of respiration which is clearly faster than heart rate in all fish species studied. This differs from the slow ventilation frequency displayed by many mammalian species that exerts an influence on a beat-to-beat basis (respiratory sinus arrhythmia). Spectral patterns could also be affected by changing levels of circulating catecholamines, although this is still unproved.

The frog brainstem preparation as a model for studying the central control of breathing in tetrapods

Our frog brainstem preparation revealed mechanisms for the central control of breathing that are in many ways similar to those of mammals. Thus, the basic control mechanisms for air-breathing appear to have been present in the Devonian common ancestors of frogs and mammals and may be common to all lung-breathing vertebrates. Location: The in vitro frog brainstem, including motor nuclei of cranial nerves V to X, maintains frequency and ratio of fictive buccal oscillations to fictive lung inflation episodes comparable with that of the living animal. In this preparation, transaction caudal to V abolishes spontaneous discharge in X but slow, spontaneous discharge in V may remain. Independent central pattern generation is present in the left and right half-brainstems. Chemosensitivity: The frequency of fictive lung inflation increases with decrease in pH within the physiological range. Response to glutamate: Biphasic response, consisting of a pause, followed by a dramatic increase in the frequency of fictive inspirations and positive baseline deflection, followed, in turn, by slow return of the baseline to the control level with frequency remaining above control as long as glutamate is applied. Local application reveals glutamate-sensitive sites in the ventral reticular formation. Response to substance P and physalaemin: Similar to glutamate but the frequency of fictive inspirations decreases below control values. Response to strychnine: The normal temporal sequence in firing of motor neurons of cranial nerves is disrupted and all nerves are synchronously active. The firing sequence of respiratory neurons is consistent with a grouping possibly homologous to the mammalian inspiratory, post-inspiratory and expiratory phases.

Efecto de tres esquemas terapéuticos sobre el flujo máximo espiratorio y la estancia hospitalaria en la crisis asmática / Effect of three therapeutic modalities upon peak expiratory flow and hospital staying in asthmatic crisis

El objetivo del presente estudio es evaluar el impacto de tres esquemas terapéuticos sobre el flujo máximo espiratorio (FME) y la estancia hospitalaria en pacientes adultos con crisis asmática. Se trata de un diseño causiexperimental, prospectivo, aleatorio, ciego simple y comparativo. Se estudiaron 38 pacientes adultos con diagnóstico de crisis asmática que se distribuyeron en tres grupos: 14 (36.84 por ciento) fueron tratados con aminofilina, 11 (28.94 por ciento con hidrocortisona y 13 (34.22 por ciento) con metilprednisolona. En cada grupo se asoció salbutamol nebulizado y se igualaron dosis de esteroides por la distinta potencia antiinflamatoria. Se medió el flujo máximo espiratorio (FME), grado de broncoespasmo, frecuencia cardiaca y respiratoria, repitiéndose dichas mediciones cada seis horas antes de la administración de los fármacos correspondientes. Se anotó la hora en que desaparecieron las sibilancias en cada grupo y se compararon entre sí. Los datos obtenidos sugieren que los tres esquemas terapéuticos empleados son adecuados y no impactan significativamente uno sobre el otro respecto al FME y la estancia hospitalaria