RESUMEN
BACKGROUND: Chronic obstructive pulmonary disease (COPD) affects millions of people and has limited treatment options. Surgical treatments for severe COPD with emphysema are effective for highly selected patients. A minimally invasive method for treating emphysema could decrease morbidity and increase acceptance by patients. OBJECTIVE: To study the safety and effectiveness of the IBV(R) Valve for the treatment of severe emphysema. METHODS: A multicenter study treated 91 patients with severe obstruction, hyperinflation and upper lobe (UL)-predominant emphysema with 609 bronchial valves placed bilaterally into ULs. RESULTS: Valves were placed in desired airways with 99.7% technical success and no migration or erosion. There were no procedure-related deaths and 30-day morbidity and mortality were 5.5 and 1.1%, respectively. Pneumothorax was the most frequent serious device-related complication and primarily occurred when all segments of a lobe, especially the left UL, were occluded. Highly significant health-related quality of life (HRQL) improvement (-8.2 +/- 16.2, mean +/- SD change at 6 months) was observed. HRQL improvement was associated with a decreased volume (mean -294 +/- 427 ml, p = 0.007) in the treated lobes without visible atelectasis. FEV(1), exercise tests, and total lung volume were not changed but there was a proportional shift, a redirection of inspired volume to the untreated lobes. Combined with perfusion scan changes, this suggests that there is improved ventilation and perfusion matching in non-UL lung parenchyma. CONCLUSION: Bronchial valve treatment of emphysema has multiple mechanisms of action and acceptable safety, and significantly improves quality of life for the majority of patients.
Asunto(s)
Neumonía/epidemiología , Neumotórax/etiología , Complicaciones Posoperatorias/epidemiología , Prótesis e Implantes , Enfisema Pulmonar/cirugía , Adulto , Anciano , Análisis de los Gases de la Sangre , Broncoscopía , Remoción de Dispositivos , Prueba de Esfuerzo , Femenino , Humanos , Mediciones del Volumen Pulmonar , Masculino , Persona de Mediana Edad , Oxígeno/uso terapéutico , Proyectos Piloto , Neumonía/etiología , Estudios Prospectivos , Prótesis e Implantes/efectos adversos , Circulación Pulmonar , Enfisema Pulmonar/diagnóstico por imagen , Enfisema Pulmonar/mortalidad , Calidad de Vida , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: Previous investigations have identified significant interobserver variability in the measurements of central venous pressure and pulmonary artery occlusion pressure in critically ill patients. Large interobserver variability in the measurement of vascular pressures could potentially lead to inappropriate treatment decisions. OBJECTIVE: We postulated that adding an airway pressure signal (Paw) to pressure tracings of central venous pressure and pulmonary artery occlusion pressure would improve interobserver agreement by facilitating identification of end-expiration. DESIGN: To test this hypothesis, six independent experts used a standard protocol to interpret strip-chart recordings of central venous pressure and pulmonary artery occlusion pressure with or without Paw. Two observers were said to agree if their measurements were within 2 mm Hg of each other. SETTING/SUBJECTS/INTERVENTIONS: A total of 459 strip-chart recordings (303 without Paw and 156 with Paw) were obtained from 121 patients enrolled in the ARDSnet Fluids and Catheters Treatment Trial (FACTT) in 16 different hospitals. RESULTS: Agreement within 2 mm Hg between two measurements was 79% for central venous pressure strips without Paw vs. 86% with Paw. For pulmonary artery occlusion pressure, agreement increased from 71% without Paw to 83% with Paw. The increase in agreement with the addition of Paw was greater for strips demonstrating >8 mm Hg phasic respiratory variation compared with strips demonstrating less phasic respiratory variation. CONCLUSION: Paw display is a simple, inexpensive method to facilitate the identification of end-expiration that can significantly improve interobserver agreement.
Asunto(s)
Resistencia de las Vías Respiratorias/fisiología , Determinación de la Presión Sanguínea/estadística & datos numéricos , Presión Venosa Central/fisiología , Cuidados Críticos/métodos , Lesión Pulmonar , Variaciones Dependientes del Observador , Respiración con Presión Positiva/métodos , Presión Esfenoidal Pulmonar/fisiología , Síndrome de Dificultad Respiratoria/terapia , Humanos , Presión Hidrostática , Capacitación en Servicio , Monitoreo Fisiológico/estadística & datos numéricos , Garantía de la Calidad de Atención de Salud , Reproducibilidad de los Resultados , Síndrome de Dificultad Respiratoria/fisiopatología , Procesamiento de Señales Asistido por Computador , TransductoresRESUMEN
OBJECTIVE: To determine the accuracy of a technique using capnography to prevent inadvertent placement of small-bore feeding tubes and Salem sump tubes into the lungs. SETTING: Twelve-bed medical intensive care unit (MICU) in a 557-bed teaching hospital. PATIENTS: A total of 25 ventilated adult MICU patients were studied-5 in phase 1 and 20 in phase 2. DESIGN: Phase 1 tested the ability of the end-tidal CO2 (ETCO2) monitor to detect flow (and thus accurately detect CO2) through small-bore feeding tubes. A small-bore feeding tube, with stylet in place, was placed 5 cm through the top of the tracheostomy tube ventilator adapter in five consecutive patients. The distal end of the feeding tube was attached to the ETCO2 monitor. The ETCO2 level and waveform were assessed and recorded. Because CO2 waveforms were successfully detected, a convenience sample of 20 adult MICU patients who were having feeding tubes placed (13 Salem sump tubes, 7 small-bore feeding tubes) was then studied. The technique consisted of attaching the ETCO2 monitor to the tubes and observing the ETCO2 waveform throughout placement. RESULTS: The study hypothesis was supported. Of the seven small-bore feeding tubes tested, all were successfully placed on initial insertion. Placement was confirmed by absence of an ETCO2 waveform and by radiograph. Of the 13 Salem sump tubes, 9 were placed successfully on first attempt and confirmed by absence of CO2 and by air bolus and aspiration of stomach contents. ETCO2 waveforms were detected with insertion of four of the Salem sump tubes; the tubes were immediately withdrawn, and placement was reattempted until successful. CONCLUSIONS: The technique described is a simple, cost-effective method of assuring accurate gastric tube placement in critically ill patients.
Asunto(s)
Capnografía , Cuidados Críticos , Intubación Gastrointestinal/métodos , Adulto , Nutrición Enteral , Diseño de Equipo , Humanos , Unidades de Cuidados Intensivos , Intubación Gastrointestinal/instrumentaciónRESUMEN
Tracheostomy continues to be a standard procedure for the management of long-term ventilator-dependent patients. Traditionally the procedure has been performed by surgeons in the operating theater using an open technique. This routine practice has recently been challenged by the introduction of bedside percutaneous dilatational tracheostomy (PDT), which has been reported to be a cost-effective alternative. The purpose of this study is to evaluate and compare the safety, procedure time, cost, and utilization of percutaneous and surgical tracheostomies at a university hospital. A retrospective medical chart review was performed on all ventilator-dependent intensive care unit patients at the University of Virginia Medical Center undergoing tracheostomy during a 23-month period beginning December 26, 1996. Of the 213 patients identified for review, 74 and 139 patients received percutaneous and surgical tracheostomies, respectively. Of 74 percutaneous tracheostomies, 73 reviewed were performed by general surgeons, pulmonary physicians, or anesthesiologists in the intensive care unit; all open tracheostomies were performed by surgeons in the operating room, and one percutaneous procedure was performed in the operating room. Perioperative complications occurred in five of 74 patients (6.76%) during PDT; of these, three patients (4.1%) experienced major complications requiring emergent operative exploration of the neck. Three patients (2.2%) experienced perioperative complications during surgical tracheostomy. The mean procedure time was significantly shorter for the percutaneous procedure. Average charges per patient in an uncomplicated case including professional fees, inventory, bronchoscopy (if performed), and operating room charges were $1753.01 and $2604.00 for percutaneous and standard tracheostomies, respectively. These charges do not include the charges associated with surgical intervention after PDT complications. In contrast to previously published reports showing complications clustered during a physician's first 30 percutaneous cases, our study demonstrated no relationship between complication occurrence and physician experience. That is, no learning curve associated with performing PDT was evident. In addition there was no association seen between physician specialty and complication rate. PDT in the intensive care unit costs less than surgical tracheostomy performed in the operating room and can be performed in less time. Several other studies have recommended that bronchoscopy during PDT provides additional safety; however, in our series all three major complications took place during bronchoscopy-assisted percutaneous procedures. Our series suggests that PDT carries an appreciable risk of major complications. Careful patient selection and additional experience with the procedure may decrease complication rates to an acceptable level.
Asunto(s)
Complicaciones Posoperatorias/etiología , Traqueostomía/efectos adversos , Traqueostomía/métodos , Adolescente , Adulto , Anciano , Femenino , Costos de Hospital , Humanos , Masculino , Persona de Mediana Edad , Procedimientos Quirúrgicos Mínimamente Invasivos/efectos adversos , Procedimientos Quirúrgicos Mínimamente Invasivos/economía , Procedimientos Quirúrgicos Mínimamente Invasivos/métodos , Traqueostomía/economíaRESUMEN
Thirty-two magnetic resonance imaging examinations of the lungs were performed in 16 subjects after inhalation of 1-2 L of helium 3 gas that was laser polarized to 10%-25%. The distribution of the gas was generally uniform, with visualization of the fissures in most cases. Ventilation defects were demonstrated in smokers and in a subject with allergies. The technique has potential for evaluating small airways disease.
Asunto(s)
Helio , Pulmón/patología , Imagen por Resonancia Magnética/métodos , Administración por Inhalación , Adulto , Anciano , Asma/patología , Femenino , Helio/administración & dosificación , Humanos , Procesamiento de Imagen Asistido por Computador , Isótopos , Rayos Láser , Pulmón/fisiopatología , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Oxígeno/sangre , Enfisema Pulmonar/patología , Respiración , Rinitis Alérgica Estacional/patología , Fumar/patologíaRESUMEN
OBJECTIVE: To determine the incidence of obstruction and colonization in adult patients in the surgical and medical intensive care units who received inner cannula changes daily versus those who did not. DESIGN: Quasi-experimental prospective study using a convenience sample of patients randomly assigned to one of two methods. SETTING: Mid-Atlantic university-affiliated tertiary care center. PATIENTS: Sixty patients within 24 hours of receiving a surgical tracheostomy. OUTCOME MEASURES: Obstruction and bacterial colonization of inner cannula. INTERVENTIONS: All inner cannulas were checked daily for obstruction and cultured on postoperative days 1 and 3. RESULTS: No statistically significant difference was noted in colonization (p = 0.13) between protocols, and no obstructions were noted in either. CONCLUSION: The study suggests that the routine practice in critical care units of changing tracheostomy inner cannulas may be unnecessary. Although the results of this study are limited, and may not be generalized to other populations, it demonstrates that practice standards related to the care of tracheostomy inner cannula need to be challenged.
Asunto(s)
Intubación Intratraqueal/enfermería , Traqueostomía/enfermería , Adulto , Infecciones Bacterianas/epidemiología , Costos y Análisis de Costo , Equipos Desechables , Femenino , Humanos , Intubación Intratraqueal/instrumentación , Masculino , Proyectos Piloto , Estudios Prospectivos , Respiración Artificial , Factores de Tiempo , Traqueostomía/instrumentaciónRESUMEN
BACKGROUND: Outcomes management that uses critical pathways may decrease costs while improving outcomes for patients who require prolonged mechanical ventilation. OBJECTIVE: To study the efficacy of an outcomes-managed approach to weaning patients from prolonged (more than 3 days) mechanical ventilation. METHODS: A method of multidisciplinary care delivery was designed that included an outcomes manager, a care pathway for patients receiving mechanical ventilation, and weaning protocols. Data collection consisted of three parts: a retrospective review of 124 patients who required prolonged ventilation during a 1-year period before implementation of the care model, a 6-month prospective study in which 91 patients were alternately assigned by month to an outcomes-managed approach or a non-outcomes-managed approach, and a 6-month prospective study of 90 patients in which an outcomes-managed approach without alternate-month assignment was used. RESULTS: Outcomes management had no significant effect on total duration of mechanical ventilation or length of stay in the hospital, days of mechanical ventilation without tracheostomy, days of mechanical ventilation with tracheostomy, or outcome (weaned, withdrawal from mechanical ventilation, death, or transfer without weaning). However, duration of mechanical ventilation was 1.3 days shorter, length of stay in the hospital was 2.1 days shorter, and the cost per case was $ 3341 less for patients in the outcomes-managed group than for patients in the non-outcomes-managed group. CONCLUSION: Outcomes-managed care did not have a significant effect on duration of ventilation, length of stay in the hospital, or outcome in patients receiving long-term mechanical ventilation.
Asunto(s)
Vías Clínicas , Evaluación de Procesos y Resultados en Atención de Salud , Desconexión del Ventilador/métodos , Adulto , Anciano , Cuidados Críticos , Estudios de Evaluación como Asunto , Femenino , Humanos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Manejo de Atención al Paciente/métodos , Planificación de Atención al Paciente , Estudios Prospectivos , Proyectos de Investigación , Estudios Retrospectivos , Factores de Tiempo , TraqueostomíaRESUMEN
OBJECTIVE: A clinical study was undertaken to define optimal preoperative strategies and intraoperative techniques that would result in the least morbidity and maximum physiologic improvements in patients with end-stage emphysema selected for lung volume reduction surgery. BACKGROUND: Lung volume reduction surgery recently has been advocated as an alternative or a bridge to lung transplantation for patients with end-stage chronic obstructive pulmonary disease. The risks, benefits, and long-term results have not been clarified. METHODS: Twenty-six patients underwent lung volume reduction surgery with a 3-month follow-up on 17 patients. Preoperative and postoperative changes in pulmonary function parameters, quality of life, and oxygen requirement were analyzed. The value of preoperative localization of diseased lung segments and how this affects intraoperative resection is addressed. RESULTS: Forty-nine percent improvement in FEV1 (forced expiratory volume in 1 second) and 23% improvement in FVC (forced vital capacity) were seen after lung volume reduction surgery. Supplemental oxygen requirement was decreased and 79% of patients reported a much better quality of life. Mortality was 3.8% and air leak morbidity was 18%. CONCLUSIONS: Lung volume reduction surgery can predictably improve objective and subjective pulmonary function in selected patients with end-stage emphysema with low morbidity and mortality. Careful patient selection, accurate preoperative localization of diseased target areas, skilled anesthetic technique, meticulous operative approach, and intense postoperative support are essential to achieve favorable results.
Asunto(s)
Selección de Paciente , Neumonectomía/métodos , Adulto , Anciano , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Neumonectomía/instrumentación , Neumonectomía/estadística & datos numéricos , Complicaciones Posoperatorias/epidemiología , Enfisema Pulmonar/mortalidad , Enfisema Pulmonar/fisiopatología , Enfisema Pulmonar/cirugía , Pruebas de Función Respiratoria/estadística & datos numéricos , Grapado Quirúrgico/métodos , Resultado del Tratamiento , Virginia/epidemiologíaRESUMEN
BACKGROUND: Despite extensive data acquired in the area of weaning, clinicians still struggle with the questions of how and when to begin the process. Clinical weaning indices, designed to predict weaning potential, are often difficult to use. They provide an answer at a specific time; extrapolation to the weaning process is rarely possible. No single index has proven to be superior. OBJECTIVES: To test the efficacy of five clinical weaning indices (Burns Weaning Assessment Program; Weaning Index; frequency tidal volume ratio; compliance, resistance, oxygenation and pressure index; and negative inspiratory pressure) at regular intervals during withdrawal of ventilatory support and to determine threshold levels for the program. METHODS: A prospective convenience sample consisted of 37 adult critical care patients requiring mechanical ventilation for at least 7 days and identified as stable and ready to wean. Data were collected on all weaning indices every other day until the patient was weaned. RESULTS: With the exception of the Burns Weaning Assessment Program, weaning indices did not change significantly from preweaning scores. Furthermore, the results failed to demonstrate that any of the five clinical weaning indices have strong predictive power related to weaning trial outcomes, although all the indices had negative predictive values that may be helpful in predicting unsuccessful weaning trials. CONCLUSIONS: The results of this study suggest that the process of weaning may be enhanced by comprehensive, systematic approaches and that clinical weaning indices like the Burns Weaning Assessment Program might best serve as tools to track trends in progress, keep care planning on target, and prevent unsuccessful weaning trials.
Asunto(s)
Evaluación en Enfermería/métodos , Índice de Severidad de la Enfermedad , Desconexión del Ventilador/métodos , Desconexión del Ventilador/enfermería , Adulto , Anciano , Anciano de 80 o más Años , Análisis de los Gases de la Sangre , Investigación en Enfermería Clínica , Protocolos Clínicos , Femenino , Humanos , Mediciones del Volumen Pulmonar , Masculino , Persona de Mediana Edad , Registros de Enfermería , Valor Predictivo de las Pruebas , Estudios Prospectivos , Resultado del TratamientoRESUMEN
Atelectasis is a major factor in postoperative morbidity for patients undergoing cardiopulmonary surgery. We evaluated the effectiveness of stacked inspiratory spirometry (STIS) in 17 patients status postcoronary artery bypass graft in a nonrandomized fashion. We measured pulmonary shunt as an endpoint, and compared the magnitudes before and after the STIS maneuver. Our results showed an 8.66 percent reduction in pulmonary shunt (p < 0.05). The reduction in shunt was modest; however, repetitive maneuvers might result in greater improvement.
Asunto(s)
Puente de Arteria Coronaria , Complicaciones Posoperatorias/prevención & control , Atelectasia Pulmonar/prevención & control , Intercambio Gaseoso Pulmonar , Espirometría/métodos , Anciano , Ejercicios Respiratorios , Estudios de Evaluación como Asunto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Oxígeno/sangre , Resultado del TratamientoRESUMEN
Bedside monitoring of respiratory status is designed to measure specific parameters and alert the clinician when these parameters exceed the limits of a desired range. Parameters should include measures of respiratory mechanics, oxygenation, and ventilation. Monitoring is the only form of communication between the physician and a patient receiving neuromuscular blocking agents. Airway pressure tracing alone, or in conjunction with concurrent flow, measures respiratory system mechanics, resistance, compliance, and the work of breathing. Pulse oximetry reflects oxygenation, while mixed venous oximetry indicates the balance between oxygen supply and demand. Capnography is a noninvasive way of assessing ventilation. Taken as a whole, noninvasive monitoring provides useful information, reflecting trends in oxygenation, ventilation, and mechanics. This article reviews the concepts of noninvasive monitoring of critically ill patients. Emphasis is given to the patient receiving neuromuscular blocking agents.
Asunto(s)
Monitoreo de Drogas/métodos , Bloqueantes Neuromusculares/uso terapéutico , Respiración Artificial/efectos adversos , Mecánica Respiratoria , Resistencia de las Vías Respiratorias , Pruebas Respiratorias , Dióxido de Carbono/análisis , Protocolos Clínicos , Cuidados Críticos/métodos , Árboles de Decisión , Humanos , Oximetría , Examen Físico , Mecánica Respiratoria/efectos de los fármacosRESUMEN
OBJECTIVE: This study evaluates the efficacy of personally inspecting marginal thoracic organ donors to expand the donor pool. SUMMARY BACKGROUND DATA: The present donor criteria for heart and lung transplantation are very strict and result in exclusion of many potential thoracic organ donors. Due to a limited donor pool, 20-30% of patients die waiting for transplantation. METHODS: The authors have performed a prospective study of personally inspecting marginal donor organs that previously would have been rejected by standard donor criteria. RESULTS: Fourteen marginal hearts and eleven marginal lungs were inspected. All 14 marginal hearts and 10 of the marginal lungs were transplanted. All cardiac transplant patients did well. The mean ejection fraction of the donor hearts preoperatively was 39 +/- 11% (range 15-50%). Postoperatively, the ejection fraction of the donor hearts improved significantly to 55 +/- 3% (p < 0.002). Nine of the ten lung transplant patients did well and were operative survivors. Our donor pool expanded by 36% over the study period. CONCLUSIONS: The present donor criteria for heart and lung transplantation are too strict. Personal inspection of marginal thoracic donor organs will help to maximize donor utilization.
Asunto(s)
Trasplante de Corazón/normas , Trasplante de Pulmón/normas , Donantes de Tejidos , Corazón/fisiología , Humanos , Pulmón/metabolismo , Pulmón/fisiología , Intercambio Gaseoso Pulmonar , Volumen Sistólico , Donantes de Tejidos/provisión & distribución , Estados UnidosRESUMEN
The maximal pressure that can be generated during an inspiratory effort against an occluded airway serves as an index of respiratory muscle strength. We devised a method that permits accurate measurement of MIP, with near maximal values, and does not require patient cooperation. Twenty-two critically ill intubated patients performed MIP maneuvers before and after coaching. For the initial 11 patients, MIP was measured after the airway was occluded in 20 s with a one-way valve that permitted only exhalation. In the latter 11 patients, DS (approximately 1/3 VT) was added in an effort to increase respiratory drive before the noncoached MIP maneuver. We found no significant difference between coached and noncoached MIP maneuvers when P0.1 during the first 100 ms of inspiratory efforts prior to the noncoached MIP maneuver was greater than 2 cm H2O. Thus, MIP can be reliably measured in critically ill patients with or without coaching.
Asunto(s)
Cooperación del Paciente , Pruebas de Función Respiratoria/métodos , Adulto , Anciano , Enfermedad Crítica , Femenino , Humanos , Unidades de Cuidados Intensivos , Masculino , Persona de Mediana Edad , Presión , Ventilación Pulmonar , Respiración Artificial , Espacio Muerto RespiratorioRESUMEN
We hypothesized that the ventilatory capacity needed to wean from mechanical ventilation (mv) depends on two variables: ventilatory endurance and the efficiency of gas exchange. We also hypothesized that these variables could be assessed from data readily available at the bedside, including tidal volume (VT) on mv and during spontaneous breathing (sb), ventilator peak inspiratory pressure (Ppk), and patient negative inspiratory pressure (NIP). Ventilatory endurance was evaluated using a modified pressure-time index: PTI = TI/Ttot x Pbreath/NIP, where Pbreath = Ppk x VTsb/VTmv. Defining VE40 as the minute ventilation needed to bring PaCO2 to 40 mm Hg, the efficiency of gas exchange was evaluated by calculating VE40/VTsb = (VE x PaCO2)mv/VTsb x 40. Because high levels of inspiratory effort might cause patients to reduce VTsb and thereby compromise CO2 elimination, we devised a weaning index (WI) that combines ventilatory endurance and the efficiency of gas exchange: WI = PTI x (VE40/VTsb). The study population comprised 38 patients with chronic obstructive pulmonary disease, adult respiratory distress syndrome, pneumonia, neuromuscular disease, and miscellaneous other conditions. They had been mechanically ventilated more than 3 days and were considered by clinical criteria to be ready for weaning. Of 46 weaning trials, 19 were successful, 2 were partially successful, and 25 failed. PTI and VE40/VTsb were higher in patients who failed (p less than 0.05), but neither variable alone had sufficient sensitivity or specificity to predict the outcome of weaning trials accurately.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Intercambio Gaseoso Pulmonar , Músculos Respiratorios/fisiopatología , Desconexión del Ventilador , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Evaluación como Asunto , Humanos , Enfermedades Pulmonares Obstructivas/fisiopatología , Enfermedades Pulmonares Obstructivas/terapia , Persona de Mediana Edad , Enfermedades Neuromusculares/complicaciones , Neumonía/fisiopatología , Neumonía/terapia , Síndrome de Dificultad Respiratoria/fisiopatología , Síndrome de Dificultad Respiratoria/terapia , Insuficiencia Respiratoria/etiología , Insuficiencia Respiratoria/fisiopatología , Insuficiencia Respiratoria/terapia , Mecánica RespiratoriaRESUMEN
The critical care clinician commonly encounters patients with acute bronchospasm. Therapy includes a multidrug regimen of sympathomimetics, anticholinergics, methylxanthines, and corticosteroids. The best use of these agents is predicated on knowledge and avoidance of drug toxicities. This article reviews toxic effects of these bronchodilator agents.
Asunto(s)
Broncodilatadores/efectos adversos , Cuidados Críticos , Corticoesteroides/efectos adversos , Corticoesteroides/uso terapéutico , Broncodilatadores/uso terapéutico , Humanos , Unidades de Cuidados Intensivos , Parasimpatolíticos/efectos adversos , Parasimpatolíticos/uso terapéutico , Teofilina/efectos adversos , Teofilina/uso terapéuticoRESUMEN
Lung transplantation is now established as a clinical reality for patients with irreversible, lethal pulmonary conditions. We report the first successful application of this treatment modality in Virginia.
Asunto(s)
Trasplante de Pulmón , Fibrosis Pulmonar/cirugía , Humanos , Trasplante de Pulmón/métodos , Masculino , Persona de Mediana Edad , VirginiaRESUMEN
In recent years, four square-wave modes of pressure-preset mechanical ventilation (PPV)--pressure control, pressure support, inverse ratio, and airway pressure release ventilation--have been introduced to clinical practice. Conceptually, they share important features. Yet, because there remains widespread uncertainty regarding their ventilatory characteristics, efficacy, and appropriate use, the potential range of application is only now being investigated. To construct a unifying mathematical model of PPV, we developed a system of equations for prediction of the major "outcome" variables of PPV--tidal volume, minute ventilation, auto-positive end-expiratory pressure, mean alveolar pressure, and mechanical work--from the primary clinical "inputs" from patient (resistance, compliance) and clinician (applied pressure, frequency, inspiratory time fraction). Our analysis revealed distinct bounding limits for the outcome variables of ventilation and pressure and important implications for their clinical determinants. Although simplifying assumptions were required to enable construction of this mathematical analogue of respiratory system behavior, this model provides a firm conceptual framework for understanding the physiological interactions between PPV and the patients they are intended to help.