The use of non-invasive positive pressure ventilation (NIPPV) in ALS patients. A need for improved determination of intervention timing.

We present our experience with 27 patients with symptoms of alveolar hypoventilation, a precursor to respiratory failure, to demonstrate variability in symptoms, physiologic status and outcome of intervention. They represent 27 consecutive patients who tolerated NIPPV for more that 4 hours per 24-h period for more than 2 weeks. All patients received neurological consultation, electromyography and met criteria for ALS according to El Escorial diagnostic criteria. To assess respiratory status, spirometry was measured in sitting and when possible, in the supine positions. Resting arterial blood gases were available in 22 patients. Orthopnea was the most common symptom at the time of institution of NIPPV. No correlation existed between age at institution of NIPPV, duration of effective use of this technology or vital capacity and duration of effective use of NIPPV. The lack of correlation between vital capacity at the institution of NIPPV and duration of its effectiveness suggest that more sensitive indicators for the onset of alveolar hypoventilation must be defined, particularly since the principal benefit from its use is relief of symptoms of alveolar hypoventilation.

Neuromuscular disease and hypoventilation.

Alveolar hypoventilation associated with neuromuscular disease can occur in acute and chronic forms. In the acute form, progressive weakness of respiratory muscles leads to rapid reduction in vital capacity followed by respiratory failure with hypoxemia and hypercarbia. Symptoms are those of acute respiratory failure, including dyspnea, tachypnea, and tachycardia. In the chronic form, impairment of the respiratory muscles affects mechanical properties of the lungs and chest wall, decreases the ability to clear secretions, and eventually may alter the function of the central respiratory centers. Symptoms include orthopnea, fatigue, disturbed sleep, and hypersomnolence. Treatment and outcome of the disease's chronic form are dependent on the underlying clinical cause of the alveolar hypoventilation. For chronic but stable diseases such as old polio, quadriplegia, or kyposcoliosis, mechanical support of minute ventilation can reverse symptoms. For chronic and progressive disease such as muscular dystrophy and amyotrophic lateral sclerosis, mechanical support of minute ventilation provides only symptomatic relief and is usually associated with deterioration to the point of complete ventilator dependency for survival. For the chronic progressive forms of alveolar hypoventilation, there is currently a need for quality randomized controlled clinical trials to define physiologic indicators and appropriate timing for mechanical support of minute ventilation.

Quality assessment in the medical intensive care unit. Continued evolution of a data model.

Quality assessment and assurance activities in the intensive care unit are complex processes that begin with the definition of the scope of services delivered in the unit with further identification of the important aspects of care. There is also a need to establish indicators of quality, gather data, and finally to organize the data into useful information. There are many approaches to these efforts ranging from establishment of indicators to data collection and analysis of patterns that lead to clarification of the indicators. We chose the latter pathway, specifically utilizing a previously described data model in which information was grouped according to structure, process, and outcome of patient care. In this paper, we focus on the application of the concept of patient days of service for quantification of the utilization of resources as an element of quality. Efficient utilization of resources cannot be effected until data on actual utilization are collected and analyzed.

Demographics of long-term ventilator-dependent patients outside the intensive care unit.

Continued management of clinically stable ventilator-dependent patients in the intensive care unit is controversial, given the expense and limitations of intensive care resources. A proposed alternative, which could reduce the cost of care, has been "noninvasive respiratory units." We review the management of 99 ventilator-dependent patients on routine nursing floors to define our case mix and the outcome of long-term care.

Management of ventilator dependency following heart surgery.

The foregoing discussion has reviewed the concept that postoperative ventilator dependency following heart surgery is due to a combination of risk factors, partly due to the nature of the patient population and partly to the process of patient care. Weaning from mechanical ventilation has been a controversial topic for decades, but the issue of rehabilitation before successful weaning has only recently achieved recognition. The fact that this process is often prolonged suggests that a certain logic must be used during the rehabilitation process. Appropriate minimization of risks with continued mechanical ventilation and concise protocols for gradually withdrawing support of mechanical ventilation may insure the quality of the patient care process. It should be understood by both the physician and patient that the ventilator for the patient population discussed previously acts merely as a "crutch" that will facilitate the process of rehabilitation.

Quality assessment in the medical intensive care unit: evolution of a data model.

Quality assessment and assurance in the intensive care unit require systematic monitoring and evaluation of patient care and its outcome. For analysis of these activities, data must be organized to reflect changes in such factors as patient types, ages, and lengths of stay. A model was developed to group data from the Cleveland Clinic Hospital medical intensive care unit into structural, process, and outcome categories. Development and application of the model are described.

Planning and management of long-standing tracheostomy.

Long-term effects of tracheostomy can include structural changes in the anterior tracheal wall and larynx as a result of pressure, friction, and deformation by the relationship between the curved cannula, the trachea, the larynx, and the upper border of the sternum. High-placed stoma, flexed cervical position, and short, obese necks are predisposing anatomic relationships. In some long-standing tracheostomies, progressive erosion of the upper anterior tracheal wall and cricoid arch is observed, often with secondary subglottic stenosis. No discussion of measures to prevent or correct these problems was found in a review of the literature. This article discusses surgical techniques to (1) prevent laryngotracheal erosion and (2) repair and reconstruct an airway that is already damaged. A superiorly based tracheostomy flap and a muscular sling are designed to buttress the tracheostomy. Results and follow-up are also reported.

Respiratory insufficiency in adult-onset acid maltase deficiency.

Although the adult form of acid maltase deficiency is characterized by weakness of the limb girdle muscles, weakness of the respiratory muscles out of proportion to that of the limb muscles may make the diagnosis less obvious. We present four patients aged 35 to 57 with respiratory muscle weakness associated with signs of cor pulmonale and symptoms of alveolar hypoventilation. Each had symptoms of fatigue, hypersomnolence, morning headache, and orthopnea, the cause of which was misdiagnosed. The key to diagnosis was paradoxic abdominal motion on inspiration. This finding, consistent with diaphragmatic paralysis, led to neurologic evaluation, electromyographic examination, and muscle biopsy to confirm the diagnosis. The symptoms of alveolar hypoventilation were reversed with chronic nocturnal ventilation, which assisted in rehabilitating some patients.

Clinical measurement of extravascular lung water.

The thermal-dye technique for the measurement of ELW is available for clinical and experimental use. This method is safe and can be performed serially in an individual patient. Although it is invasive, it requires only a central venous catheter and an arterial catheter, which are often already in place for routine hemodynamic monitoring and management. The procedure is accurate under a variety of conditions. Two obstacles argue against its routine application. First, the reliability of this approach appears to be seriously compromised when there are areas of edematous lung with poor blood perfusion. This includes aspiration and perhaps other forms of acute lung injury. Second, it remains to be demonstrated how useful routine measurements of ETVL, even if accurate, are in clinical management. However, regardless of the accuracy of the various methods for determination of ELW, the process of their development has significantly enhanced our knowledge of pulmonary edema formation and fluid distribution. We are at a transition point of soon being able to determine ELW easily. Techniques of reducing ELW can now be assessed directly in patients with pulmonary edema. As these therapies are developed and understood, the demand for the measurement of ELW will become a greater part of clinical medicine, and may stimulate further refinement of methods for quantitating lung water.

Home care ventilation: the Cleveland Clinic experience from 1977 to 1985.

A need for long-term ventilation in the home has created a demand for home care services that has been a source of growth for an industry. Evaluation of the patient and family who will guarantee successful home care requires careful psychological and psychiatric evaluation. Beyond this evaluation, long-term success is possible if appropriate financial resources are available. The implementation of successful home care is best done by a team consisting of primary physician, primary ICU nurse, social worker, psychiatrist, and home care respiratory therapist. An appropriate classification of patients based on goals of care, as well as the study of the incidence and prevalence of associated disorders, will be helpful in the future allocation of resources.

Effects of furosemide versus isolated ultrafiltration on extravascular lung water in oleic acid-induced pulmonary edema.

We studied the effects of no treatment, furosemide treatment, and isolated ultrafiltration on extravascular lung water (ETVL) in mongrel dogs in whom pulmonary edema was induced with oleic acid. In all treatment groups, ETVL was significantly elevated 90 min after oleic acid infusion. At 270 min, we found no difference between nontreatment and furosemide. There was, however, a significant difference between no treatment and ultrafiltration but not between furosemide and ultrafiltration. In spite of observations which suggest that ultrafiltration is of benefit in reducing ETVL, we could not demonstrate superiority of one therapy over another.