LTMV-dependent patients

Several lines of evidence support the likelihood that increased mechanical load contributes to LTMV dependence. First, mechanical load is greater in ventilator-dependent patients than in non-ventilator-dependent patients (41,43). Second, progression to successful weaning has been associated with improvement in work of breathing per liter of minute ventilation, which is a function of compliance, resistance, tidal volume, and minute ventilation (48). Third, the mean inspiratory flow produced for a given level of neuromuscular inspiratory drive is lower in LTMV-dependent patients than in patients who are successfully weaned after a period of PMV (Fig. 3) (41,43). Lastly, effective inspiratory impedance correlates with inspiratory pressure output (41). This correlation suggests worse load-capacity balance in patients who are dependent on LTMV than in patients who are successfully weaned after a period of PMV (41). 

Several reports have commented on the optimal site for LTMV. The ICU often involves activities with regard to the patients, such as physical restraint, sedation, and depersonalization. It also lacks a rehabilitative focus, fosters dependence, and disrupts family life (7) and is therefore inappropriate for stable ventilator-dependent patients. As a consequence, several alternative locations for LTMV have been proposed. 

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. 

Malnutrition is highly prevalent among patients requiring PMV (37) and LTMV (70) and is assoeiated with poor prognosis (71). Malnutrition decreases muscle mass and respiratory muscle strength and enduranee (40). These effects on the respiratory muscles are partially reversible with nutritional support. The process, however, is slow, and in laboratory animals, it can take months of refeeding for muscle mass to return to normal values (72). To date, it remains unclear whether malnutrition by itself ean cause sufficient respiratory muscle weakness to produce ventilator dependence. It is more likely for malnutrition to be a contributing factor and not a sole cause of ventilator dependence. 

Nearly 50% of patients requiring PMV or LTMV carry a preexisting diagnosis of coronary artery disease, left ventricular failure, or right ventricular failure (37). Therefore, impaired cardiovascular performance may contribute to ventilator dependence in many patients. So far, few case reports have shown that successful diuresis and weight loss may be... 

Being dependent on life support poses unique demands and stressors on LTMV patients, which result in psychological difficulties. These may include loss of autonomy and control, disruption of plans for the future, uncertainty about the future, permanent changes in physical appearance and bodily function, inability to communicate effectively, and diminished roles and responsibilities in the family and the society. 

Survival beyond respiratory failure may last months or years [when mechanical ventilation (MV) is used] (1-3). When planning optimal management of care, physicians and health care providers may unintentionally overlook crucial problems regarding the needs of family caregivers who are held hostage in their homes. Those who are severely disabled and ventilator dependent rarely visit their physicians. Furthermore, health care professionals may have limited experience in observing LTMV patients in the home setting. 

The number of patient families with hired caregivers varied widely, and was dependent on their health care benefits and/or their incomes. Surprisingly, many families were unaware of their specific health care benefits, both before and after commencement of LTMV. In the United States, patients with poverty status actually obtained the most health care benefits. 

By understanding the perspectives of your family caregivers, you can help your patient families avoid misconceptions, obtain necessary information for making best choices, and help them to achieve and maintain the best life possible. The outcomes of family caregivers and their loved ones using LTMV may depend on you. 

Other challenges may override the medical issues. Financial resources are limited, and in the United States, reimbursement has driven the current care process. These issues will continue to be the major force shaping the nature of care for LTMV patients. The availability of institutions for placement of chronically ventilated patients as well as the infrastructure to manage LTMV patients in the home all depend on funding. Ethical issues also influence the management of chronically ill patients. These issues are considered below. 

---