Mechanical ventilation in chronic obstructive lung disease

Extracorporeal carbon dioxide removal for acute hypercapnic respiratory failure

In the past, the only treatment of acute exacerbations of obstructive diseases with hypercapnic respiratory failure refractory to medical treatment was invasive mechanical ventilation (IMV). Considerable technical improvements transformed extracorporeal techniques for carbon dioxide removal in an attractive option to avoid worsening respiratory failure and respiratory acidosis, and to potentially prevent or shorten the duration of IMV in patients with exacerbation of COPD and asthma. In this review, we will present a summary of the pathophysiological rationale and evidence of ECCO₂R in patients with severe exacerbations of these pathologies.

Brazilian recommendations of mechanical ventilation 2013. Part I

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumonia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.

Brazilian recommendations of mechanical ventilation 2013. Part I

Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumologia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.

Long-term survival in patients with tracheostomy and prolonged mechanical ventilation in Olmsted County, Minnesota

BACKGROUND

An increasing number of patients require prolonged mechanical ventilation (PMV), which is associated with high morbidity and poor long-term survival, but there are few data regarding the incidence and outcome of PMV patients from a community perspective.

METHODS

We retrospectively reviewed the electronic medical records of adult Olmsted county, Minnesota, residents admitted to the intensive care units at the 2 Mayo Clinic Rochester hospitals from January 1, 2003, to December 31, 2007, who underwent tracheostomy for PMV.

RESULTS

Sixty-five patients, median age 68 years (interquartile range [IQR] 49-80 y), 39 male, underwent tracheostomy for PMV, resulting in an age-adjusted incidence of 13 (95% CI 10-17) per 100,000 patient-years at risk. The median number of days on mechanical ventilation was 24 days (IQR 18-37 d). Forty-six patients (71%) survived to hospital discharge, and 36 (55%) were alive at 1-year follow-up. After adjusting for age and baseline severity of illness, the presence of COPD was independently associated with 1-year mortality (hazard ratio 3.4, 95% CI 1.4-8.2%).

CONCLUSIONS

There was a considerable incidence of tracheostomy for PMV. The presence of COPD was an independent predictor of 1-year mortality.

[Invasive mechanical ventilation in COPD and asthma]

COPD and asthmatic patients use a substantial proportion of mechanical ventilation in the ICU, and their overall mortality with ventilatory support can be significant. From the pathophysiological standpoint, they have increased airway resistance, pulmonary hyperinflation, and high pulmonary dead space, leading to increased work of breathing. If ventilatory demand exceeds work output of the respiratory muscles, acute respiratory failure follows. The main goal of mechanical ventilation in this kind of patients is to improve pulmonary gas exchange and to allow for sufficient rest of compromised respiratory muscles to recover from the fatigued state. The current evidence supports the use of noninvasive positive-pressure ventilation for these patients (especially in COPD), but invasive ventilation also is required frequently in patients who have more severe disease. The physician must be cautious to avoid complications related to mechanical ventilation during ventilatory support. One major cause of the morbidity and mortality arising during mechanical ventilation in these patients is excessive dynamic pulmonary hyperinflation (DH) with intrinsic positive end-expiratory pressure (intrinsic PEEP or auto-PEEP). The purpose of this article is to provide a concise update of the most relevant aspects for the optimal ventilatory management in these patients.

Clinical review: patient-ventilator interaction in chronic obstructive pulmonary disease

Mechanically ventilated patients with chronic obstructive pulmonary disease often prove challenging to the clinician due to the complex pathophysiology of the disease and the high risk of patient-ventilator asynchrony. These problems are encountered in both intubated patients and those ventilated with noninvasive ventilation. Much knowledge has been gained over the years in our understanding of the mechanisms underlying the difficult interaction between these patients and the machines used to provide them with the ventilatory support they often require for prolonged periods. This paper attempts to summarize the various key issues of patient-ventilator interaction during pressure support ventilation, the most often used partial ventilatory support mode, and to draw clinicians' attention to the need for sufficient knowledge when setting the ventilator at the bedside, given the often conflicting goals that must be met.

Evaluation of a pumping assist lung that uses a rotating fiber bundle

A paracorporeal respiratory assist lung (PRAL) is being developed for supplemental gas exchange to allow the native lungs of acute lung failure patients to heal. The device consists of a rotating annular microporous hollow fiber membrane bundle. The rotation augments the gas exchange efficiency of the device at constant flow-rate thereby uncoupling gas exchange and flow rate. The rotating fibers also enable the PRAL to pump the blood without the need for an additional pump or arterial cannulation. Blood flow rates will be between 500 and 750 ml/min with CO(2) removal rates of 100-130 ml/min. A prototype was manufactured with an overall surface area of 0.25 m. When rotated at 1500 rpm, CO(2) removal increased by 133% and O(2) transfer increased by 157% during an in vitro bovine blood study. The pumping of the rotating fiber bundle was assessed in a glycerol/water solution. At 1500 rpm, the PRAL generated 750 ml/min against 52 mm Hg pressure. Hemolysis of the device was assessed using in vitro bovine blood from a slaughterhouse. Plasma free hemoglobin levels were similar regardless of whether the rotating fibers were present in the PRAL, indicating that a rotating fiber bundle can be used to increase gas exchange without causing blood trauma.

Chronic obstructive pulmonary disease in geriatric critical care

COPD is a progressive disorder that is punctuated in its later stages with acute exacerbations that present a risk for respiratory failure. COPD has a disproportionate impact on older patients. In the ICU, therapy is directed toward unloading fatigued respiratory muscles, treating airway infection, and prescribing bronchodilatory drugs. Most patients survive hospitalization in the ICU for an episode of respiratory failure. The severity of the underlying lung disease, however, underlies the poor outcomes of patients in terms of postdischarge survival and quality of life.

Positive pressure mechanical ventilation

There have been numerous advances in the application of positive pressure mechanical ventilation in the last two decades. As knowledge of pulmonary physiology expands, the application of modes and parameters to maximize the efficacy and minimize the complications of ventilatory support continues to advance. As the use of noninvasive ventilation becomes more widespread, its usefulness in certain clinical entities such as COPD exacerbations and acute cardiogenic pulmonary edema will become more prominent. The role of specific modes and parameters of these devices likely will be further refined to maximize outcomes.

Ventilation of patients with asthma and chronic obstructive pulmonary disease

Ventilatory intervention is often life-saving when patients with asthma or chronic obstructive pulmonary disease (COPD) experience acute respiratory compromise. Although both noninvasive and invasive ventilation methods may be viable initial choices, which is better depends upon the severity of illness, the rapidity of response, coexisting disease, and capacity of the medical environment. In addition, noninvasive ventilation often relieves dyspnea and hypoxemia in patients with stable severe COPD. On the basis of current evidence, the general principles of ventilatory management common to patients with acutely exacerbated asthma/COPD are these: noninvasive ventilation is suitable for a relatively simple condition, but invasive ventilation is usually required in patients with more complex or more severe disease. It is crucial to provide controlled hypoventilation, longer expiratory time, and titrated extrinsic positive end-expiratory pressure to avoid dynamic hyperinflation and its attendant consequences. Controlled sedation helps achieve synchrony of triggering, power, and breath timing between patient and ventilator. When feasible, noninvasive ventilation often facilitates the weaning of ventilator-dependent patients with COPD and shortens the patient's stay in the intensive care unit.