An observational study of characteristics, outcome and survival for difficult to wean patients referred to a regional ventilation unit
Ford, V., Parker, R., Angus R., Chakrabarti, B., Duffy, N., Manuel, A., Plant, P., Ashcroft, H., Ward, K.
Most patients requiring invasive mechanical ventilation within the critical care unit will wean relatively quickly without the need for specialist weaning services. However, there are a small proportion who struggle to wean off ventilatory support and consume a disproportionate amount of bed days and resources. The NHS commissioning services identified the need for specialist centres to facilitate weaning and discharge of these patients; and to free up valuable critical care beds. There are still relatively few of these units within the UK.
This unit has 4 beds to support weaning patients. This study looks at the characteristics, outcome and survival of difficult to wean patients admitted to a small regional ventilation unit.
The Ventilation Inpatient Centre (VIC) was opened in January 2010 and fully established to accept weaning patients in October 2010. It was based on commissioning from NHS North West to provide a complex home ventilation service, building on 25 years of providing the regional home NIV service. It is located at Aintree University Hospital in Liverpool, alongside the regional sleep service.
The first 5 years of data is included (October 2010- October 2015), all patients admitted for weaning to the unit were included in the analysis, demographics outcome and survival were collected during admission and retrospectively using hospital records and follow up data.
Patients were weaned using a multidisciplinary approaching with regular input from speech and language, clinical psychology, occupational therapy, dietician, and daily input from doctors, nurses and specialist physiotherapists who jointly plan weaning progression.
The focus of care is on rehabilitation, reducing daytime pressure support, optimal nocturnal support, early cuff deflation and speaking valve use. Spontaneous daytime ventilation was secured before assessing the need for nocturnal support, NIV was used as bridge to early decannulation and ongoing need for NIV assessed and provided where needed.
95 admissions (85 individuals, some multiple admissions). Median age was 61.0 years, and 67.4% were male. The median length of stay on the referring ICU before transfer was 48 days. Most common reason for admission to ICU; respiratory failure 72.6% of which 68.1% was due to pneumonia. Thirteen (13.7%) were admitted to ICU after surgery.
A comparison of characteristics of patients that died (8.4%) to survivors showed they were older (72.5 v’s 61years), had a longer admission to their initial ICU before transfer (65 v’s 45 days), and more significant ventilatory failure on transfer as evidenced by higher pCO2 (7.58 v’s 6.56kPa) and bicarbonate (34.7 vs 30.7 mmol/L).
Longer term survival, 73.7% were alive 6 months, and 68.4% at 12 months after hospital discharge.
Outcome: 8% died on the unit, 18% required long term tracheostomy ventilation, 33% required no long term ventilatory support and 41% required NIV at discharge. As a subgroup, COPD weaned the quickest, 95.2 % were discharged alive and the majority (55%) required or wished no ongoing ventilatory support, and for those that did it was provided by nocturnal NIV in all cases. Ninety percent were discharged directly home and 85% were alive one year after discharge.
Patients did well most returning home, only small proportion did not survive to discharge or required long term invasive ventilation. NIV was used to support just under half of all patients demonstrating a proportion whose failure to wean was due to the need for ongoing ventilatory nocturnal support which the ventilation unit had the skills and experience to manage.