Is it the destination or the journey?

I want to discuss 3 slightly related studies today.  All are early release article from Critical Care, but that’s not all they have in common.  They all have to do with location.  Any good real-estate agent will tell you that it’s all about location, and it would appear it’s the same for intensive care too.  Where you go, and how you get there, appear to make a difference.  While this shouldn’t come as much of a surprise, it’s a politically tricky issue.

The first study is a large retrospective case-control registry study from England and Wales.  They looked a patients who were transferred from one ICU to another for “non-clinical” reasons (i.e. not for neurosurgery or liver transplant or some other regional specialist service) or  within 48 hours of admission to ICU.  The reasons for transfer weren’t available from the registry data, but one would have to presume that lack of beds or staff was high up the list.

The authors identified 308,323 patients admitted to 198 ICUs between January 2008 and September 2011.  About 4000 patients were excluded for various reasons, and 759 were identified  as having been transferred within 48 hours for non-clinical reasons.  Each of these was then matched with 2 controls.

While unable to identify an effect of transfer on mortality, the authors noted a statistically significant increase in ICU stay of 3.2 days (95%CI 2.1-4.3, p<0.001) in those who were transferred for non-clinical reasons.

How odd.  Surely a trip down the road in an ambulance can’t add 3 days to your ICU stay?  Did they not have transport ventilators?  Was the poor SHO doing mouth-to-tube resuscitation the whole way?  The authors postulate that “physiological upset from transport” or something to that effect could have had an effect.  But 3 days?  Odd.  I work in a region that transfers patients between ICUs very frequently, so I’d be interested to see if the results were transferrable, and whether an organised, well trained retrieval medicine service would make a difference.

The next 2 studies are from continental Europe.  First from Germany where the authors again used registry data to look at the outcome of out-of-hospital-cardiac-arrest (OOHCA) patients based on what hospital they got taken to.  Specifically whether they were taken to a centre capable of percutaneous coronary intervention (PCI) or not.  Now in Germany critically ill patients are looked after by doctor-paramedic teams prehospital, so the doctors were able to use their clinical judgement to decide where to take the patient.  There were no protocols, as there are for trauma and stroke, for example.

The authors identified 889 patients who had a cardiac arrest in Dortmund (city population 580,000; but metro population 5.2 million) in 2008.  Children and patients with traumatic cardiac arrest were excluded, as were those with incomplete data.  The numbers all seem pretty standard; 63% male, median age 69, 26% in VF or VT, 52% witnessed, 82% at home, 13% bystander CPR, 40% ROSC, 10.9% survival to hospital discharge (I had to calculate that myself, always makes me suspicious.)  The outcome they were interested in was the effect of destination hospital on survival to discharge and neurological status at one year.

They found that patients taken directly to a PCI centre were younger, more likely to have a presumed cardiac aetiology, more likely to have ROSC in the field and more likely to have had a GCS of 15 before collapsing.  Once they got the PCI centre, patients were more likely to get a PCI (obviously – but only 50% did) but also more likely to get an echo within 2 hours of arrival and to get therapeutic hypothermia.  They were had a longer ICU stay, more days of mechanical ventilation and were more likely to have an ICD inserted.

The odds ratio for survival to discharge for those taken to PCI centre was 4.5 (!) (40% vs 16% discharged alive).  There was a similar difference in 1 year survival but  no significant difference in neurological outcome.

This sounds pretty amazing.  Even if you don’t get a PCI you do better if taken to a PCI capable hospital after your OOHCA.  But actually, what I think this study shows is exactly the opposite – you get taken to a PCI centre if you’re more likely to survive.  Patients taken to the PCI centres were younger, had likely cardiac aetiology for their arrests, got ROSC prehospital and were less likely to be disabled premorbidly.  There was a big selection bias here.  The young guys who got ROSC after one shock went to the PCI centre sitting up in the back of the ambulance chatting about how lucky they were, while the 90 year olds from the nursing home went to the community hospital in asystole with CPR in progress.  Actually, thats a bit mean.  I have just said that more of the patients in the PCI centre group were ventilated in ICU for longer.  I’m just not sure that this study says anything earth shattering, however I”m happy to be proved wrong if someone thinks I’ve misread it.

I do think it was an interesting and well thought out study though.  It would have been nice to have a bit more data on the patients, like how many of those taken to the non-PCI centre died in the ED (i.e. were dead when they arrived).  But what this study does say to me is that EMS providers (be they docs or paramedics) should be able to take a patient to the hospital that they believe is best, not the closest one.  In a large city with lots of hospitals, it just makes sense for the most critically ill patients to be taken to large tertiary centres with large ICUs staffed by specialist intensivists, senior trainees and very experienced nurses.  We’ve known this for a long time for trauma, and it amazes me that it’s taking so long for us to catch up with cardiac arrest, which is far more common.

Finally, a study (again retrospective) from France looking at the effect of the mode of transport, rather than the destination, on mortality.    Now this one was pretty interesting. They looked at 1,958 patients admitted to French university hospital ICUs with severe trauma (ISS >15) over a 3 year period.  They compared mortality at 30 days or hospital discharge between those brought to hospital by ambulance and those brought in by helicopter.  Now in France the crewing of both modalities is the same (doctor/nurse/driver or pilot) so you’d expect there to be no difference in the care received.  And you’d be wrong.

Looking at the data first.  74% were transported by road, 24% by helicopter.  Mean ISS was the same (25) but there was more hypotension (SBP <90) in the helicopter group.  Prehospital time was significantly longer in the helicopter group (surprise, surprise) at 2.3 vs 1.8 hours.  Yes, you read that right, around 2 hours in both groups.  And here was I thinking that 20 minutes on scene with a trauma patient was a long time.  It isn’t clear what effect entrapment had on these times.  Oh, and the helicopter group had more procedures prehospital (intubation, chest decompression, transfusion).  Although crude mortality was the same between the 2 groups, An adjusted analysis (for male gender, time of day, seriousness of accident) showed a decreased risk of death in the helicopter group (0.68, p=0.035)

So despite spending longer playing with their toys in the field, the helicopter crews were able to improve survival.   But how? The authors of the study don’t know, but postulate that the helicopters tend to be crewed by doctors and nurses from larger, regional hospitals whereas the road ambulances tend to be crewed by docs and nurses from smaller community hospitals.  So it may be the experience and decision making ability of the more experienced helicopter crews that makes the difference.  Food for thought anyway.

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