Terapia de presión negativa para pacientes con enfisema subcutáneo y neumomediastino masivo / Negative pressure therapy for patients with subcutaneous emphysemaand massive pneumomediastinum

Se han descrito diversas técnicas para el tratamiento del enfisema subcutáneo y del neumomediastino. Algunos pacientes con pequeñas perforaciones traqueales pueden ser manejados de forma expectante, salvo que requieran ventilación mecánica. Se presentan las imágenes de un paciente con enfisema subcutáneo y neumomediastino no candidato a cirugía y quien fue tratado exitosamente con terapia de presión negativa.

Different techniques have been described for the treatment of subcutaneous emphysema and pneumomediatinum. Some patients with small tracheal perforations can be managed expectantly, unless they require mechanical ventilation. Images of a patient with subcutaneous emphysema and pneumomediastinum not a candidate for surgery and who was successfully treated with negative pressure therapy are presented.

Impact of negative pressure system on microbiological air quality in a Central Sterile Supply Department.

OBJECTIVE: Guidelines recommend that the cleaning area in a Central Sterile Supply Department (CSSD) maintain a negative pressure of the environmental air, but how much this system can impact the contamination of the air by bioaerosols in the area is not known. The objective of this study was to assess the impact of negative pressure on CSSD by evaluating the microbiological air quality of this sector. METHODS: Microbiological air samples were collected in two CSSD in the same hospital: one with and one without a negative air pressure system. Outdoor air samples were collected as a comparative control. Andersen six-stage air sampler was used to obtain the microbiological air samples. RESULTS: The concentration of bioaerosols in the CSSD without negative pressure was 273.15 and 206.71 CFU/m3 , while in the CSSD with negative pressure the concentration of bioaerosols was 116.96 CFU/m3 and 131.10 CFU/m3 . The number of isolated colonies in the negative pressure CSSD was significantly lower (P = .01541). CONCLUSION: The findings showed that the negative pressure system in the CSSD cleaning area contributed to the quantitative reduction in bioaerosols. However, the concentration of bioaerosols was lower than that established in the guideline for indoor air quality of many countries. Therefore, it cannot be concluded that CSSDs which do not have a negative pressure system in their cleaning area offer occupational risk.

Edema pulmonar por presión negativa con máscara laríngea clásica. Presentación de un caso pediátrico / Pulmonary edema due to negative pressure with classical laryngeal mask. Presentation of a pediatric case

RESUMEN El edema pulmonar por presión negativa es una complicación rara y dramática en la anestesia general. Habitualmente ocurre como consecuencia de un laringoespasmo u otra causa de obstrucción de la vía aérea. Se presentó un caso con el objetivo de mostrar los elementos usados para el diagnóstico y tratamiento del edema pulmonar por presión negativa. Paciente de 7 años de edad, femenina, ASA I, operada de metatarso varo funcional con anestesia general balanceada y máscara laríngea clásica # 3. Desarrolló dicho evento adverso durante la recuperación anestésica. El diagnóstico se basó en la disociación toraco abdominal al restablecer la ventilación espontanea, crepitantes en ambos hemitórax, cianosis central, hipoxemia y la presencia de infiltrado difuso bilateral alveolar. Se intubó la tráquea, se controló la ventilación con presión positiva al final de la espiración y se administró furosemida. La paciente fue trasladada a la Unidad de Cuidados Intensivos donde evolucionó satisfactoriamente. Este es un síndrome cuya verdadera incidencia se desconoce debido a la escasa familiarización con el mismo. La evolución de los pacientes es favorable siempre que se establezca el diagnóstico y el tratamiento oportuno (AU).

ABSTRACT Pulmonary edema due to negative pressure is a rare and dramatic complication in general anesthetic. It usually occurs as a consequence of a laryngeal spasm or another cause of respiratory tract obstruction.A case was presented with the aim of showing the elements used for the diagnosis and treatment of the pulmonary edema due to negative pressure. An ASA I, 7-year-old female patient, was operated on a functional metatarsus varus with balanced general anesthetic and classical laryngeal mask number 3. She developed this adverse event during the anesthetic recovery. The diagnosis was based on the thoracoabdominal dissociation when recovering spontaneous ventilation, crepitation in hemithoraxes, central cyanosis, hypoxemia, and alveolar bilateral diffused infiltrate. The trachea was intubated, ventilation was controlled with positive pressure at the end of the expiration and furosemide was administered. The patient was transferred to the Intensive Care Unit where she evolved satisfactorily. This is a syndrome whose true incidence is unknown as a result of the lack of familiarization with it. Patients' evolution is favorable whenever the right diagnosis and treatment are timely established (AU).

Edema pulmonar por presión negativa con máscara laríngea clásica. Presentación de un caso pediátrico / Pulmonary edema due to negative pressure with classical laryngeal mask. Presentation of a pediatric case

RESUMEN El edema pulmonar por presión negativa es una complicación rara y dramática en la anestesia general. Habitualmente ocurre como consecuencia de un laringoespasmo u otra causa de obstrucción de la vía aérea. Se presentó un caso con el objetivo de mostrar los elementos usados para el diagnóstico y tratamiento del edema pulmonar por presión negativa. Paciente de 7 años de edad, femenina, ASA I, operada de metatarso varo funcional con anestesia general balanceada y máscara laríngea clásica # 3. Desarrolló dicho evento adverso durante la recuperación anestésica. El diagnóstico se basó en la disociación toraco abdominal al restablecer la ventilación espontanea, crepitantes en ambos hemitórax, cianosis central, hipoxemia y la presencia de infiltrado difuso bilateral alveolar. Se intubó la tráquea, se controló la ventilación con presión positiva al final de la espiración y se administró furosemida. La paciente fue trasladada a la Unidad de Cuidados Intensivos donde evolucionó satisfactoriamente. Este es un síndrome cuya verdadera incidencia se desconoce debido a la escasa familiarización con el mismo. La evolución de los pacientes es favorable siempre que se establezca el diagnóstico y el tratamiento oportuno (AU).

ABSTRACT Pulmonary edema due to negative pressure is a rare and dramatic complication in general anesthetic. It usually occurs as a consequence of a laryngeal spasm or another cause of respiratory tract obstruction.A case was presented with the aim of showing the elements used for the diagnosis and treatment of the pulmonary edema due to negative pressure. An ASA I, 7-year-old female patient, was operated on a functional metatarsus varus with balanced general anesthetic and classical laryngeal mask number 3. She developed this adverse event during the anesthetic recovery. The diagnosis was based on the thoracoabdominal dissociation when recovering spontaneous ventilation, crepitation in hemithoraxes, central cyanosis, hypoxemia, and alveolar bilateral diffused infiltrate. The trachea was intubated, ventilation was controlled with positive pressure at the end of the expiration and furosemide was administered. The patient was transferred to the Intensive Care Unit where she evolved satisfactorily. This is a syndrome whose true incidence is unknown as a result of the lack of familiarization with it. Patients' evolution is favorable whenever the right diagnosis and treatment are timely established (AU).

Ventilación mecánica: una breve historia / Mechanical ventilation: a short history

This review is a short history of mechanical ventilation, from its origins to the present day. This changing history provides the basis for speculation on the future innovations in the ventilatory support.

Se revisa la historia de la ventilación mecánica desde sus orígenes hasta el presente, una historia cambiante que permite especular sobre las futuras innovaciones en el soporte ventilatorio.

Edema pulmonar por presión negativa / Negative pressure pulmonary edema

El edema pulmonar por presión negativa representa el 0.1% de las complicaciones pulmonares de los pacientes post ­ quirúrgicos, y la condicionante del incremento de dicha incidencia es la existencia de algún tipo de obstrucción de la vía aérea llegando hasta un 11% de casos. Su incidencia y prevalencia no son claras ya que es una entidad con infradiagnóstico. En los reportes de casos se coincide que la mayoría de pacientes son jóvenes con evaluaciones de riesgo quirúrgico bajos previamente sanos y que desarrollan en forma súbita un cuadro de edema agudo de pulmón, casi siempre posterior a la anesthesia, encontrándose ya no orointubados...(AU)

Edema pulmonar por presión negativa. Reporte de caso / Pulmonary edema by negative pressure. Case report

El edema pulmonar por presión negativa representa el 0.1% de las complicaciones pulmonares de los pacientes post ­ quirúrgicos, y la condicionante del incremento de dicha incidencia es la existencia de algún tipo de obstrucción de la vía aérea llegando hasta un 11% de casos. Su incidencia y prevalencia no son claras ya que es una entidad con infradiagnóstico. En los reportes de casos se coincide que la mayoría de pacientes son jóvenes con evaluaciones de riesgo quirúrgico bajos previamente sanos y que desarrollan en forma súbita un cuadro de edema agudo de pulmón, casi siempre posterior a la anesthesia, encontrándose ya no orointubados. La intensa presión negativa intrapleural secundaria al esfuerzo inspiratorio genera en el intersticio pulmonar pericapilar el gradiente transmural suficiente para producir edema. La hipoxemia, hipercapnia, acidosis e hipersecreción adrenérgica se suman al escenario, determinando las características fisiopatológicas, clínicas, radiológicas y evolutivas de esta entidad.3-4. El edema pulmonar resultante puede aparecer en pocos minutos tras la obstrucción de la vía aérea o de forma diferida al cabo de varias horas. Este cuadro clínico es potencialmente grave, pero habitualmente responde bien al tratamiento con oxigenoterapia, en raros casos es necesaria la ventilación mecánica a presión positiva y diuréticos...(AU)

Pulmonary edema by negative pressure represents 0.1% of pulmonary complications in post - surgical patients, and the condition of the increase in this incidence is the existence of some type of airway obstruction reaching up to 11% of cases. Its incidence and prevalence are not clear since it is an entity with underdiagnosis. In the case reports it is agreed that the majority of patients are young with previously low risk surgical evaluations who develop suddenly a picture of acute pulmonary edema, almost always after anesthesia, and are no longer orointubed. The intense negative intrapleural pressure secondary to the inspiratory effort generates in the pericapillary pulmonary interstice the transmural gradient sufficient to produce edema. Hypoxaemia, hypercapnia, acidosis and adrenergic hypersecretion are added to the scenario, determining the physiopathological, clinical, radiological and evolutionary characteristics of this entity.3-4. The resulting pulmonary edema may appear within a few minutes after the obstruction of the airway or deferred after several hours. This clinical picture is potentially serious, but usually responds well to treatment with oxygen therapy, in rare cases it is necessary mechanical ventilation at positive pressure and diuretics ... (AU)  

Instrumentation for the analysis of airflow limitation by the negative expiratory pressure technique.

The aim of this work is to describe a new instrument based on the negative expiratory pressure technique able to detect expiratory flow limitation (EFL) in patients with respiratory diseases. First, we describe the design details of a virtual instrument able to apply a low pressure at the mouth during tidal expiration, simultaneously measure flow and pressure, and automatically elaborate flow-volume curves. Then, the system accuracy is evaluated investigating normal subjects and patients with chronic obstructive pulmonary disease (COPD). These experimental results revealed higher (p〈0.001) EFL in COPD patients (58.5±19.9%) than in normal volunteers (1.5±2.5%). These results are in close agreement with the physiology, confirming the high scientific and clinical potential of this system.

Single-lung ventilation with contralateral lung deflation: a simplified method for multivessel off-pump coronary artery bypass grafting.

There are many new alternative methods of minimally invasive myocardial revascularization that can be applied in selected patients who have multivessel coronary artery disease. However, these techniques often require new and expensive equipment. Most multivessel myocardial revascularization is performed via median sternotomy and involves the use of a conventional endotracheal tube. Both lungs are ventilated, and frequently the left pleural cavity is opened. In contrast, single-lung deflation naturally moves the mediastinum within the thorax toward the collapsed lung, without the need to open the pleural cavities. Herein, we describe a simple alternative procedure that facilitates off-pump multivessel coronary artery bypass grafting via complete median sternotomy: single-lung ventilation with contralateral lung deflation. This technique better exposes the more distal right and circumflex coronary artery branches with or without the opening of the pleural cavities.

Análise do efeito das manobras de pressäo negativa e da sustentaçäo máxima da inspiraçäo dos volumes pulmonares / Analysis of negative pressure maneuver effect and the inspiration maxima sustentation in the lung volume

O objetivo deste trabalho foi verificar o efeito das manobras de pressäo negativa (MPN) e compará-la com a sustentaçäo máxima da inspiraçäo (SMI) em pacientes que apresentam diminuiçäo da capacidade vital (CV). Foram estudados 5 pacientes paraplégicos do sexo masculino, com lesäo nível T2-T6, há no mínimo 1 ano e com ausência de patologias pulmonares. Cada participante foi submetido a MPN e SMI aleatoriamente em diferentes dias. Antes e após a terapia foi realizada a espirometria e a mensuraçäo da frequência respiratória e durante a terapia foi registrada a saturaçäo de oxigênio (SatO2) e frequência cardíaca. Na MPN foram realizadas 3 séries de 15 repetiçöes. Todas as técnicas foram feitas com o indíviduo na posiçäo sentada, com duraçäo média de 15 minutos. Os pacientes submetidos a MPN näo apresentaram diferenças espirométricas significativas, porém os pacientes submetidos a SMI apresentaram aumento do volume de reserva inspiratório (VRI), queda do volume de reserva expiratório (VRE), queda do volume corrente (VC) e queda do fluxo inspiratório (VC/Ti). A SatO2 näo variou durante as terapias. A SMI mostrou-se mais efetiva do que a MPN em pacientes com reduçäo da CV.

Trabajo respiratorio según el grado de sensibilidad de disparo por flujo en pacientes con ventilación en soporte por presión / Work of breathing according flow by triggering level in patients on pressure support ventilation

El disparo por flujo (Flow-by) como modo de disparo disminuye el trabajo respiratorio impuesto (WOBp) en modalidades de asistencia mecánica ventilatoria espontáneas. Objetivo: Determinar el efecto del disparo por flujo sobre el WOBp en ventilación en soporte por presión como variante de retiro. Pacientes y métodos: Fueron estudiados sujetos con asistencia mecánica ventilatoria prolongada o de difícil retiro. Se les determinó el WOBp, usado un monitor pulmonar Bicore. Se usó disparo por flujo con flujo base de 12 L/min y se determinó el WOBp a diferentes grados de sensibilidad del disparo por flujo: 6, 3 y 1 L/min; y a dos niveles de ventilación en soporte por presión: alto (nivel al iniciar modalidad espontánea) y bajo (nivel previo a la extubación). Se usaron ventiladores NPB-7200. Para la interpretación estadístico se empleó el análisis de varianza (ANOVA) y t de Student. Resultados: Se incluyeron 12 pacientes (ocho hombres y cuatro mujeres) con edad promedio de 62.9 ñ 14.4 años. En nivel alto de ventilación en soporte por presión (15.3 ñ 3.7 cm H2O), los WOBp con sensibilidad del disparo por flujo de 6.3 y 1 L/min fueron, respectivamente; 0.19 ñ 0.30 J/L, 0.15 ñ 0.28 J/L y o.12 ñ 0.27 J/L. A niveles bajos de ventilación en soporte por presión (5.8 ñ 1.1 cm H2O), los WOBp con sensibilidad del disparo por flujo de 6, 3 y 1 L/min fueron, respectivamente: 1.26 ñ 0.50 J/L, 1.05 ñ 0.42 J/L y =.79 ñ 0.40 J/L. Sólo hubo diferencia estadística en el WOBp con ventilación en soporte por presión de ni vel bajo a sensibilidad del disparo por flujo de 6 (1.26 ñ 0.50 J/L) vs 1 (0.79 ñ 0.40 J/L), p< 0.05. Los tubos endotraqueales fueron de 8.2 ñ 0.3 mm. Conclusiones: El WOBp desciende con menores grados de sensibilidad del disparo, y aparece diferencia estadística a nivel bajo de ventilación en soporte por presión. Sugerimos el uso de la sensibilidad más baja (1L/min) en pacientes de difícil destete

Ventilaçäo com pressäo negativa: estudo experimental em gatos / Negative pressure ventilation: experimental study in cats

Os autores compararam, em 22 gatos adultos, os efeitos da ventilaçäo com pressäo negativa (VPN) e da ventilaçäo com pressäo positiva (VPP), sobre a pressäo arterial, temperatura corpórea e conteúdo de água pulmonar. A VPN foi realizada com aparelho Emerson Chest Respirator Pump e a VPP, manualmente, com um AMBU. Os gatos foram estudados em três grupos: a) grupo de dez animais submetidos à quatro horas de VPN, com valores de pressäo pleural progressivamente negativos; b) grupo de sete animais mantidos por 90 minutos em ventilaçäo espontânea e por 30 minutos com VPP, com nível de hiperventilaçäo semelhante à VPN; c) grupo de cinco animais, näo submetidos a nenhuma das duas modalidades de ventilaçäo e sacrificados imediatamente para determinaçäo do conteúdo normal de água pulmonar. Foram alcançados níveis significativamente elevados de ventilaçäo pulmonar (PaCo2;13mmHg) em ambos os grupos. Houve diminuiçäo da pressäo arterial média em ambos os grupos, mas ela foi mais acentuada no grupo VPN (69mmHg - p < 0,05), sendo os valores mais baixos associados aos níveis altos de hiperventilaçäo. A temperatura corpórea diminuiu em ambos os grupos, porém a diminuiçäo foi maior no grupo VPN. O conteúdo de água pulmonar elevou-se discretamente nos dois grupos, sem haver predominância nas regiöes dependentes. Concluímos que: 1) é possível ventilar com VNP animais com alta complascência dos sistema respiratório; 2) pode haver diminuiçäo da pressäo arterial quando elevados níveis de pressäo negativa säo aplicados; 3) a VPN pode determinar diminuiçäo da temperatura corpórea quando houver abertura no sistema que permita a entrada de ar; 4) a VPN näo foi responsável pelo aumento de conteúdo de água pulmonar nos animais estudados

Flujos sistemicos y pulmonares en ninos normales / Sistemic and pulmonary flow in normal children

Por la importancia en la determinacion de los corto circuitos arteros venosos (Qp/Qs): y para un mejor valoracion de los ninos portadores de Cardiopatias congenitas con Hipertension arterial Pulmonar; presentamos el presente trabajo en el que se analizan en 12 ninos normales, las variaciones de flujo sanguineo que ocurren a niveles proximales o distales de los grandes vass que salen del corazon. Utilizando el Doppler pulsando relaciones los diametros vasculares y demostramos los optimos sitios de interrogatcion Doppler.

Intermittent negative pressure ventilation may increase urine flow in normal subjects

Com o objetivo de avaliar o efeito da ventilaçäo por pressäo negativa intermitente (NPV) na funçäo renal, estudamos vinte indivíduos voluntários normais (idade média de 29 ñ 41 anos). A NPV foi obtida utilizando-se um respirador "Emerson Chest Respirator Pump" o qual foi ajustado para assegurar freqüência de 10 respiraçöes por minuto com relaçäo de tempo inspiratório total de 0,4 e pressäo negativa de 25 cm de água. O protocolo experimental foi desenvolvido em 2 fases com duraçäo de duas horas cada - fase de respiraçäo espontânea e fase de respiraçäo com NPV. No final de cada fase, foi medido o volume urinário e coletado sangue para as determinaçöes bioquímicas. Durante a NPV houve um aumento significante do fluxo urinário (p<0,05) (1,42 ñ 0,81 para 2,76 ñ 1,95 ml/min), da natriurese (258 ñ 201 para 389 ñ 175 mcEq/min), da caliurese (61 ñ 45 para 98 ñ 49mcEq/min), da fraçäo de excreçäo de sódio (1,38 ñ 1,82 para 4,32 ñ 1,24 ml/min) e do pH (7,37 ñ para 7,41 ñ 0,07). Os clearances de creatinina e de água livre näo se alteraram significativamente. Concluímos que a respiraçäo com NPV aumenta o fluxo urinário, a caliurese, porém nossos dados näo nos permite explicar a origem destes achados

Intermittent negative pressure ventilation may increase urine flow in normal subjects.

In order to analyze the effect of intermittent negative pressure ventilation (NPV) on renal function, we studied 20 healthy male volunteers (mean age 29 +/- 4.1 years). NPV was performed with an "Emerson Chest Respirator Pump", adjusted to a breathing frequency of 10 respirations per minute, with inspiratory time/total respiratory time ratio of 0.4 and negative pressure of 25 cmH2O. The experimental protocol was carried out in two phases of two hours each--spontaneous breathing and NPV breathing. At the end of each phase, urine volume of the whole period was collected as well as venous blood sample for biochemical determinations. During NPV there was significant increase (P < 0.05) in urine flow rate (1.43 +/- 0.81 to 2.76 +/- 1.95 ml/min) as well as in natriuresis (258 +/- 201 to 389 +/- 175 mcEq/min), kaliuresis (61 +/- 45 to 98 +/- 49 mcEq/min), fractional sodium excretion (1.38 +/- 0.88 to (1.96 +/- 0.98%), osmolar clearance (3.13 +/- 1.82 to 4.32 +/- 1.24 ml/min) and pH (7.37 +/- 0.04 to 7.41 +/- 0.07) with unchanged creatinine and free water clearances. We concluded that NPV increases urine flow rate, kaliuresis and natriuresis but the data we have do not allow us to explain the mechanisms underlying such a phenomenon.

[Intermittent negative pressure ventilation in patients with chronic air flow limitation: criteria for selection of patients]. / Ventilacion mecanica intermitente con presion negativa externa en pacientes con limitacion cronica del flujo aereo: criterios para seleccion de pacientes.

To determine clinical and functional predictive criteria for use of intermittent negative pressure ventilation we evaluated 9 patients with severe chronic air flow limitation. Arterial blood gases, lung volumes, maximal inspiratory pressures and transdiaphragmatic pressure during quiet breathing were measured. patients were then ventilated once or twice a week for 3 to 10 weeks and improvement was evaluated through changes in quality of life, dyspnea, PaO2, PaCO2 and maximal inspiratory mouth pressure (PRMAX). Result was considered good when 4 or more of these indices improved. 5 patients benefitted from intermittent negative pressure ventilation. Compared to non responders, patients who improved had significantly lower PRMAX (39.4 +/- 11.6 VS 73.5 +/- 13.8 CMh20, p < 0.025), and higher percentage of their maximal inspiratory pressure during quiet breathing (31.2 +/- 7 vs 12.2 +/- 5%, p < 0.025>). Other indices were not different between groups. We conclude that a severe impairment of inspiratory muscle function characterizes patients with chronic air flow limitation who may benefit from intermittent negative pressure ventilation.