Long-term ventilator-dependent patients

Cordasco EM, Jr., Sivak ED, Percz-Trepichio A. Demographics of long-term ventilator-dependent patients outside the intensive care unit. Cleve Clin J Med 1991 58(6) 505-509. 

Figure 8 Continuous recordings of airflow (Flow) and esophageal pressure (Pes) in a long-term ventilator-dependent patient with COPD during a brief period of unassisted breathing. Arrows indicate ineffective inspiratory efforts—inspiratory efforts not associated with inspiratory flow. In one study (41), ineffective inspiratory efforts were recorded in 40% of long-term ventilator-dependent patients with COPD but not in patients with COPD who were successfully weaned after a period of prolonged ventilatory support. Abbreviations Pes, esophageal pressure COPD, chronic obstructive pulmonary disease. Source From Ref. 41.

Figure 1 Conceptual framework linking acute or acute-on-chronic lespiratray failure to jaolonged mechanical ventilation and long-term ventilator dependence. Differences in patient population, imprecise nosology, and paucity of research make it difficult to provide solid indications for when patients may transition from one condition to the next.

Specific conditions such as idiopathic central alveolar hypoventilation syndrome (Ondine s curse) or central alveolar hypoventilation syndrome secondary to neurological lesions (trauma, infections, infarction. Shy Drager syndrome) can cause or contrihute to long-term ventilator dependence (40). In most ventilator-dependent patients, however, estimations of respiratory drive indicate that drive is increased and not decreased (18,41-43). 

The risks and benefits of distal tubular diuretics have been assessed in preterm infants under 3 weeks of age with or developing chronic lung disease (36). Acute and chronic administration of distal diuretics improved pulmonary mechanics adverse effects were not reported. However, additional studies are needed to assess whether thiazide administration improves mortality, duration of oxygen dependency, ventilator dependency, length of hospital stay, and long-term outcome in patients exposed to corticosteroids and bronchodilators, and whether adding spironolactone to thiazides or adding metolazone to furosemide has any beneficial effect. 

Goldberg AI. Long-term ventilatory support in the community. Chest 1993 103 1315-1316. Warren ML, Jarrett C, Senegal R, et al. An interdisciplinary approach to transitioning ventilator-dependent patients to home. J Nurs Care Qual 2004 19 67—73. 

Each year, over 400,000 patients in the United States receive mechanical ventilation as a result of acute or acute-on-chronic respiratory failure (1,2). About a quarter of acutely ventilated patients repeatedly fail attempts at weaning and may require prolonged mechanical ventilation (PMV) (Fig. 1) (3,4). The proportion of patients experiencing PMV ranges between 0% and 20% (5-13). Out of patients who survive PMV, 9-66% become dependent on long-term mechanical ventilation (LTMV) (4,9,14-21). Two factors account for these wide variations in the outcome. The first factor is differences in patient population. The second one is the nosology of what constitutes PMV and what constitutes LTMV is unsatisfactory. 

Purro A, Appendini L, De Gaetano A, et al. Physiologic determinants of ventilator dependence in long-term mechanically ventilated patients. Am J Respir Crit Care Med 2000 161(4 pt 1) 1115-1123. 

Meanwhile, years of productive research have demonstrated that patients with chronic respiratory insufficiency can also benefit from mechanical ventilation. As the Preface of this volume mentions their survival as well as their health status may be dependent on long-term ventilatory support. The ever increasing incidence and prevalence of chronic respiratory disease suggests that the use of ventilatory support will markedly increase. However, the techniques and strategies to use it, and when and where (non-intensive care unit, or home), are very different from treating the respiratory failure resulting from acute conditions and in patients with structurally near normal lungs. 

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