Tuesday, August 10, 2010

Prognosis of prolonged mechanical ventilation

Annals of Internal Medicine has a study looking at the long term prognosis/natural history of patients who are mechanically ventilated for a prolonged period.  This is a similar topic to one we've blogged about several times before: the chronically critically ill (e.g. here, here). 

This is a prospective, single center (Duke) study involving critically ill adults.  Patients from all ICUs were included (both medical, surgical, and neuro), and prolonged mechanical ventilation (PMV) was defined as either 21 or more days of mechanical ventilation or at least 4 days of ventilation plus tracheostomy placement with the expectation of prolonged ventilation.  Patients with preexisting tracheostomies were exlcuded.  Patients were enrolled prospectively (the study involved interviews with patients/surrogates and physicians), and were followed for up to 12 months.  Quality of life was measured with a complicated formula involving the EuroQol-5D (an index I am not familiar with). 

This study enrolled 126 patients.  On the whole, these patients were doing well at baseline:  most had no dependencies in ADLs prior to PMV.  Median ICU stay was 26 days; hospital 39 days; with 29% going to an LTAC, 18% dying during the index hospitalization, and 30% going to other facilities (e.g. SNF). 

A lot of data were generated (if you want to know the number of patients who were discharged, ventilated, to an LTAC, then got better, to an extent, but still had major functional impairment at 1 year, and what the health care costs were associated with this, read the full text of this article because it'll tell you).  The major outcomes that I think are useful in thinking about these patients were:
  • 45% had died at 1 year; those who died had a median survival of 79 days.
  • 65% of patients at 1 year had a 'poor outcome' (dead, or dependent in all ADLs)
  • 26% of patients had a 'fair' outcome (dependent in at least 1 ADL) and 9% a good outcome (no ADL dependencies) at 1 year.
  • No one who was alive but with a 'poor outcome' at 3 months (47 patients)  improved to a good outcome at 1 year (about a quarter of these improved to fair, a quarter died, and the rest remained completely functionally dependent).  Basically, at 3 months the vast majority of patients had improved as much as they were going to improve at 12 months.  For most patients whose condition changed after 3 months, it was for the worst. 
  • Predictors of poor outcomes were age, comorbidities, and whether they were discharged being ventilated, but not how severe their acute/critical illness was at the time of tracheostomy.  Trauma patients did better than non-trauma patients.  They don't give much more detail about the chronic conditions of the non-trauma patients - one wonders (hopes!) there is a sub-analysis pending looking at that. 
  • Resource utilization was high, of course.  Not to beat a dead horse here with this issue on the blog, but that's only important in the context of these resources being utilized to achieve what are dismal outcomes for these patients (most of them!). 
The authors note that perhaps 300,000 patients per year (?in the US) received prolonged mechanical ventilation, and will probably exceed 600k within a decade.  Yikes.

There are a lot of things one can discuss here and please do so in the comments.  For me, data like these should be used to help focus our, and our colleagues', discussions with patients/families about goals of care around issues of medium and long-term prognosis (not just mortality but functional outcomes).  The question about whether to place a tracheostomy and send a patient to an LTAC, for instance, should not just be about whether or not the patient can survive their current pneumonia, or heal their abdominal wound, or not, but about the long-term picture.  That the need for prolonged ventilation is, as a rule, a marker for a poor outcome on the order of months to a year.  It's what that year will entail, and how the patient, if they even survive it, will be like at its end, that is of great importance, not so much whether they are 'wean-able.' 

Some of the words from the Gawande New Yorker piece Christian posted about a couple of weeks ago ring very true here - I have these hanging on the wall of my office now:
ResearchBlogging.orgI think of Gould and his essay every time I have a patient with a terminal illness. There is almost always a long tail of possibility, however thin. What’s wrong with looking for it? Nothing, it seems to me, unless it means we have failed to prepare for the outcome that’s vastly more probable. The trouble is that we’ve built our medical system and culture around the long tail. We’ve created a multitrillion-dollar edifice for dispensing the medical equivalent of lottery tickets—and have only the rudiments of a system to prepare patients for the near-certainty that those tickets will not win. Hope is not a plan, but hope is our plan.
Unroe M, Kahn JM, Carson SS, Govert JA, Martinu T, Sathy SJ, Clay AS, Chia J, Gray A, Tulsky JA, & Cox CE (2010). One-year trajectories of care and resource utilization for recipients of prolonged mechanical ventilation: a cohort study. Annals of internal medicine, 153 (3), 167-75 PMID: 20679561

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