Short and long term outcomes in a diverse group of patients requiring prolonged weaning from mechanical ventilation
K. Aldridge, D. McWilliams, C. Dawson, R. Allen, J. Williams, C. Storrie, C. Snelson
Critical Care Unit, Queen Elizabeth Hospital Birmingham
Weaning patients from mechanical ventilation following critical illness is not always a simple process, and it is estimated that 11% of critical care beds are occupied by patients who are undergoing ‘prolonged’ weaning from mechanical ventilation, defined as >21 days of weaning in an otherwise stable patient.
Reported outcomes in such patients are variable, with some studies estimating that only 30-70% of patients who undergo prolonged weaning are successfully liberated from all mechanical ventilation at discharge from hospital. In response to these poor outcomes, some authors advocate for transfer of such patients to specialised weaning centres. However, in practice these arrangements may not be feasible, for clinical, organisational and social reasons.
At QEHB, in an effort to improve outcomes for prolonged wean patients, a weekly multi-disciplinary review of all long-stay patients is undertaken and a comprehensive individualised rehabilitation and weaning plan is devised. Patients have daily physiotherapy review, alongside regular SLT, dietetics and occupational therapy input if required. We aimed to evaluate the success of this approach by analysing outcomes of our long-stay weaning patients.
All patients with a critical care length of stay over 21 days were retrospectively identified from a two year period in 2014-2016. Electronic records were reviewed to identify those patients whose long length of stay was predominantly due to prolonged weaning.
Data on patient demographics, comorbidities, length of stay, organ support, mortality and discharge destination were collected and analysed.
Prolonged mechanical ventilation was defined as those who required ventilation for >21 days, and patients were considered to be a ‘respiratory wean’ when they were no longer receiving any other organ support.
A total of 55 patients were identified over the 2 year period, with a mean age of 69.
The primary reason for admission to ITU is displayed in Figure 1.
Patients spent an average of 48 days in critical care, and required mechanical
ventilation for 35 days.
Median Charlson co-morbidity score was 1 (Range 0-6).
The most commonly encountered co-morbidities were type 2 diabetes (8/55, 14.5%) and
pre-existing respiratory disease (13/55, 23.6%). Only 3/55 (5.5%) of patients had
On average, patients spent 48 days in critical care, and were liberated from mechanical ventilation after an average of 35 days.
44/55 (80%) of these patients survived to hospital discharge, and 42/44 surviving patients (95%) were fully liberated from mechanical ventilation at the time of hospital discharge (1 patient was transferred to a specialised weaning centre, and 1 patient had an ongoing requirement for nocturnal non-invasive ventilation). 32/50 (64%) of patients survived at least 1 year after hospital discharge.
During the weaning process, 22/55 (40%) of patients developed further periods of instability requiring fewer than 7 days of additional organ support - predominantly further episodes of sepsis requiring vasopressor support.
In total, 32/44 surviving patients were discharged to their own homes (directly or following a period of inpatient rehabilitation), and further detail on discharge destination is displayed in Figure 2.
Patient age, co-morbidity, and length of critical care or hospital stay had no impact on discharge destination, though cancer sufferers were less likely to return to their own home after discharge (p = 0.02).
Patients who died before hospital discharge were significantly more likely to have pre-existing respiratory disease (45% versus 14%, p = 0.03), but no other measured factors affected in-hospital mortality.
1 year survival was not associated with any of the measured factors.
Good weaning outcomes in those requiring prolonged mechanical ventilation following critical illness can be obtained in non-specialist weaning centres. Only two patients required ongoing ventilator support after discharge, and 1 year survival rates were comparable to those achieved by specialist units, though our cohort represented a different population than those seen in specialist centres, with fewer patients suffering from neuromuscular disease. Multi-disciplinary input was key to achieving good outcomes. The recovery process for these patients was not linear, and 40% required additional short stints of organ support during the weaning process. None of the measured factors for patients requiring PMV impacted on mortality, and further research is needed to help prognosticate for this complex patient group.