To: The reality of patients requiring prolonged mechanical ventilation: a multicenter study

OBJECTIVE: The number of patients who require prolonged mechanical ventilation increased during the last decade, which generated a large population of chronically ill patients. This study established the incidence of prolonged mechanical ventilation in four intensive care units and reported different characteristics, hospital outcomes, and the impact of costs and services of prolonged mechanical ventilation patients (mechanical ventilation dependency ≥ 21 days) compared with non-prolonged mechanical ventilation patients (mechanical ventilation dependency < 21 days). METHODS: This study was a multicenter cohort study of all patients who were admitted to four intensive care units. The main outcome measures were length of stay in the intensive care unit, hospital, complications during intensive care unit stay, and intensive care unit and hospital mortality. RESULTS: There were 5,287 admissions to the intensive care units during study period. Some of these patients (41.5%) needed ventilatory support (n = 2,197), and 218 of the patients met criteria for prolonged mechanical ventilation (9.9%). Some complications developed during intensive care unit stay, such as muscle weakness, pressure ulcers, bacterial nosocomial sepsis, candidemia, pulmonary embolism, and hyperactive delirium, were associated with a significantly higher risk of prolonged mechanical ventilation. Prolonged mechanical ventilation patients had a significant increase in intensive care unit mortality (absolute difference = 14.2%, p < 0.001) and hospital mortality (absolute difference = 19.1%, p < 0.001). The prolonged mechanical ventilation group spent more days in the hospital after intensive care unit discharge (26.9 ± 29.3 versus 10.3 ± 20.4 days, p < 0.001) with higher costs. CONCLUSION: The classification of chronically critically ill patients according to the definition of prolonged mechanical ventilation adopted by our study (mechanical ventilation dependency ≥ 21 days) identified patients with a high risk for complications during intensive care unit stay, longer intensive care unit and hospital stays, high death rates, and higher costs.

As shown in the paper, the pre-existing chronic diseases such as chronic obstructive pulmonary disease, heart failure and cancer are not only the most relevant previous conditions related to the PMV but are also three of the major indications of NIV. (3) In using NIV before invasive ventilation, we reduce the need of intubation and further complications that can lead to PMV. (4) In addition, we cannot forget the fourth major indication of NIV, ventilator weaning. Ventilator weaning reduces, in certain patients, the risk of failure to wean and also the need of a tracheostomy or re-intubation and further complications.
Regarding the complications that can lead to a PMV, the major ones include bacterial nosocomial sepsis (129 patients), pressure ulcers (86 patients), muscle weakness (71 patients), acute respiratory distress syndrome (37 patients), and hyperactive delirium (27 patients). These are all clinical situations that will benefit from NIV. Early extubation and NIV support will reduce the intubation time, and bacterial microfilm exposure, which precedes ventilator associated pneumonia, eventual acute respiratory distress syndrome and bacterial nosocomial sepsis. Once again, early tube withdrawal and NIV or even avoiding intubation will reduce the sedation and analgesia requirements, and subsequently, the risk of hyperactive delirium and intensive care neuropathy. In addition, NIV, when associated with daily, target planned physiotherapy (5) and rehabilitating respiratory techniques, offers the possibility of early mobilization, and reduces the risk of pressure ulcers and their related comorbidities.
The remarkable study of Loss et al. (1) did not include NIV data, weaning attempts using NIV, or the number of PMV patients who needed or used NIV, making it difficult to compare the NIV impact on PMV.
Finally, the major concern is the "Do Not Resuscitate" order; although it is always one of the most difficult decisions to make, it is something that we all have to face, not only once the patient is already in the ICU, but ideally many times leading up to that moment. The target is to avoid chronically critical conditions, which, in most of the cases, refers to a patient who never leaves the hospital or even passes away just a few months later at home or in any post-hospitalization support unit, especially after going through a nightmare of clinical conditions that did not translate to a good outcome. (6) Furthermore, in the case of surviving the ongoing morbidity, it will unnecessarily prolong their suffering.
Unfortunately, as shown in this paper, the present severity scores fail in regard to predicting the PMV. Certainly better and more accurate decision making protocols and severity scores than the present ones would help us on this complex and unpleasant matter. Additionally, further research is required to help us reduce chronic critical illness and the unstoppable associated costs.

Resposta dos autores
We appreciate the interest in our paper. (1) We agree with you that prolonged mechanical ventilation as part of a chronic critical illness (CCI) could be faced as an unexpected outcome of technology. We do not allow early death in our intensive care units (ICUs), but we cannot guarantee survival with quality for this type of patient. The costs associated with this population have become large (2) as well as the burden to each CCI patient and his/her family. (3,4) The potential prediction of such a population early in the ICU setting is pivotal in this context. We previously published (5) data from an observational cohort study in which we found that the concomitant combination of some conditions, such as admission to the ICU with sepsis, respiratory failure, abnormal mental status, and abnormal body mass index associated with suboptimal nutrition in the first week, could predict CCI with a probability of 90%. Others (6) have noted that we can "see" this condition (prolonged mechanical ventilation) generating in the CCI with less time of dependence of ventilation support (2 weeks). It is hard, but we believe that it is possible to detect this type of patient earlier and offer them a more specific treatment. We agree that patients with chronic diseases (such as cancer, acquired immunodeficiency syndrome, chronic cardiac or respiratory diseases) should be submitted to noninvasive ventilation (NIV) prior to invasive mechanical ventilation, but we need more evidence to use it in acute conditions. (7) We again agree with you that NIV could be a good strategy comprising this more specific treatment. Our group previously published a paper that used a NIV ventilator in tracheotomized patients with an objective of ICU-discharge. (8) However, the aim of our study (1) was not to study features regarding patients submitted to the NIV because in our reality, these patients either already have chronic behavior and most of them are part of a population readmitted to the ICU, or they already have CCI.
Finally, we must develop protocols to deliver the best treatment possible and reduce futility. NIV can be an excellent alternative for patients at risk of a chronic course and further studies should be conducted for this purpose.