Pathophysiological Basis of Acute Respiratory Failure on Non-Invasive Mechanical Ventilation.

Noninvasive mechanical ventilation (NIMV) was created for patients who needed noninvasive ventilator support, this procedure decreases the complications associated with the use of endotracheal intubation (ETT). The application of NIMV has acquired major relevance in the last few years in the management of acute respiratory failure (ARF), in patients with hypoxemic and hypercapnic failure. The main advantage of NIMV as compared to invasive mechanical ventilation (IMV) is that it can be used earlier outside intensive care units (ICUs). The evidence strongly supports its use in patients with COPD exacerbation, support in weaning process in chronic obstructive pulmonary disease (COPD) patients, patients with acute cardiogenic pulmonary edema (ACPE), and Immunosuppressed patients. On the other hand, there is poor evidence that supports the use of NIMV in other pathologies such as pneumonia, acute respiratory distress syndrome (ARDS), and during procedures as bronchoscopy, where its use is still controversial because the results of these studies are inconclusive against the decrease in the rate of intubation or mortality.

Humidification on Ventilated Patients: Heated Humidifications or Heat and Moisture Exchangers?

The normal physiology of conditioning of inspired gases is altered when the patient requires an artificial airway access and an invasive mechanical ventilation (IMV). The endotracheal tube (ETT) removes the natural mechanisms of filtration, humidification and warming of inspired air. Despite the noninvasive ventilation (NIMV) in the upper airways, humidification of inspired gas may not be optimal mainly due to the high flow that is being created by the leakage compensation, among other aspects. Any moisture and heating deficit is compensated by the large airways of the tracheobronchial tree, these are poorly suited for this task, which alters mucociliary function, quality of secretions, and homeostasis gas exchange system. To avoid the occurrence of these events, external devices that provide humidification, heating and filtration have been developed, with different degrees of evidence that support their use.

Noninvasive Mechanical Ventilation in Acute Respiratory Failure Patients: A Respiratory Therapist Perspective.

Physiotherapist in Chile and Respiratory Therapist worldwide are the professionals who are experts in respiratory care, in mechanical ventilation (MV), pathophysiology and connection and disconnection criteria. They should be experts in every aspect of the acute respiratory failure and its management, they and are the ones who in medical units are able to resolve doubts about ventilation and the setting of the ventilator. Noninvasive mechanical ventilation should be the first-line of treatment in acute respiratory failure, and the standard of care in severe exacerbations of chronic obstructive pulmonary disease, acute cardiogenic pulmonary edema, and in immunosuppressed patients with high levels of evidence that support the work of physiotherapist. Exist other considerations where most of the time, physicians and other professionals in the critical units do not take into account when checking the patient ventilator synchrony, such as the appropriate patient selection, ventilator selection, mask selection, mode selection, and the selection of a trained team in NIMV. The physiotherapist needs to evaluate bedside; if patients are properly connected to the ventilator and in a synchronously manner. In Chile, since 2004, the physioterapist are included in the guidelines as a professional resource in the ICU organization, with the same skills and obligations as those described in the literature for respiratory therapists.

Evaluación de la ventilación mecánica no invasiva en pacientes con insuficiencia respiratoria aguda / Evaluation of non-invasive ventilation in patients with acute respiratory failure

Antecedentes: Existe evidencia que avala la utilidad de la ventilación mecánica no invasiva (VMNI) en el manejo de la insuficiencia respiratoria aguda (IRA), no obstante, la definición de variables que permitan predecir el éxito o fracaso de este recurso terapéutico es controversial. Objetivo: Evaluar el comportamiento de parámetros clínicos y de laboratorio en relación con el éxito o fracaso de la VMNI en pacientes con IRA. Metodología: Estudio prospectivo de cohorte descriptivo que incluye pacientes consecutivos que cumplieron con criterios de conexión a VMNI e ingresaron a la UPC de Clínica Alemana de Santiago entre marzo de 2005 y julio de 2007. Los pacientes se dividieron en dos grupos, aquellos que fracasan con VMNI y requirieron intubación, grupo fracaso (GF) y los que no la requirieron, grupo éxito (GE). Se registraron variables demográficas, APACHE II, diagnóstico de ingreso. La mecánica respiratoria, gasometría arterial y hemodinámica se obtuvieron en tres momentos de la evolución evolución: previo a la conexión, a las dos horas y al término del uso de VMNI (preintubación y destete de VMNI). Resultados: De los 132 pacientes incluidos se logró evitar la intubación en 99 de ellos (75 por ciento), 33 fueron intubados (25 por ciento), de los cuales 1 falleció. El pH fue menor en el GF (7,42+/-0,06 v/s 7,39+/-0,08; p =0,04). La saturación de oxígeno por pulsioximetría (SpO2) también fue menor en el GF tanto a las dos horas (96+/-2 v/s 95+/-3; p=0,01) como al final del uso de VMNI (96+/-2 v/s 95+/-3; p =0,04). La PaO2/FiO2 fue menor en el mismo grupo, en los tres momentos de medición: previo a la conexión (196+/-66 v/s 144+/-59; p =0,001), a las dos horas (223+/-92 v/s 179+/-88;p =0,022) y al término del uso de VMNI (252+/-78 v/s 208+/-104; p =0,021). Al final del uso de VMNI, tanto la frecuencia cardiaca (FC) (86+/-16 v/s 94+/-20; p =0,03) como el nivel de IPAP (12+/-2 v/s 13+/-3; p =0,02) fueron mayores en el GF. Conclusiones: El GF muestra..

Background: There is evidence supporting the benefits of non-invasive ventilation (NIV) in the treatment of acute respiratory failure (ARF), however, the role of different variables in the evaluation of this technique’s success are controversial. Objective: To evaluate the performance of the different clinical parameters and relate them with the success and failure of NIV in patients with ARF. Methodology: Prospective study of descriptive cohort that includes consecutive patients who fulfilled criteria of connection to NIV and entered to the ICU (Intensive Care Unit)of Clínica Alemana de Santiago between March of 2005 to July 2007. These patients were divided into two groups, those presenting failure with NIV and required intubation, failure group (GF) and those that did not require it, success sgroup (GE). The demographic registered variables measured were APACHE II, diagnosis of entrance were registered. The respiratory mechanics, arterial gasometry and haemodynamics were obtained at three moments of the evolution: previous to the connection, the two hours and at the end of the use of NIV (pre-intubation and weaning of NIV). Results: From the 132 patients included, intubation was avoided in 99 of them (75 percent) 33 percent were entubated from which only 1 died. The pH was lower in the FG (7.42 +/- 0.06v/s 7.39 +/- 0.08; p = 0.04). The oxygen saturation by pulsometry (SpO2), was also lower in the GF after two hours (96+/-2 v/s 95+/-3; p =0.01) and at the end of NIV use (96+/-2 v/s 95+/-3; p =0.04). The PaO2/FiO2 was lower in the same group, at the three moments of measurement: previous to the connection (196+/-66 v/s 144+/-59; p =0.001), two hours post connection (223+/-92 v/s 179+/-88; p =0.022) and at the end of the NIV use (252+/-78 v/s 208+/-104; p =0.021). At the end of the NIV use both, the cardiac frequency (FC) (86+/-16 v/s94+/-20; p =0.03) and the IPAP level (12+/-2 v/s 13+/-3; p=0.02)...