A prospective observational study of paediatric patients requiring pre-hospital intubation attended by a helicopter medical team (HMT) included 95 children with a GCS of 3-4. Fifty-four received bag-mask support by EMS paramedics until the HMT arrived and intubated them (survival 63%), and 41 were intubated by EMS paramedics. Of these, ‘correction of tube/ventilation’ was required in 37% and the survival was 5%. The authors conclude that bag-mask support should be the technique of choice by EMS paramedics, as the rate of complications of tracheal intubation in this patient group is unacceptably high. Hard to comment as I only have access to the abstract but one wonders if the EMS-intubation group were sicker patients requiring more aggressive early control of airway and breathing.
Seasons Greetings! Some delicacies from this month’s literature to add to your Christmas fayre:
Some have theorised that giving thrombolytics during cardiac arrest might result in survivors in those with a thrombotic aetiology, such as MI or PE. An RCT from 10 European countries on 1050 patients may have put that idea to rest: tenecteplase and placebo had the same survival outcomes when given to out-of-hospital arrest patients prior to transport to hospital, although a seven times greater incidence (2.7% vs 0.4%) of intracranial haemorrhage in the tenecteplase group.
Speaking of pulmonary embolism, a review of the disease reminds us that a meta-analysis of 5 RCTs of thrombolysis in patients with PE and arterial hypotension or shock reduces death or recurrent PE from 19% to 9.4% compared with heparin alone (NNT = 10). The benefit is less clear in those with evidence of RV dysfunction but who are normotensive; the need for further therapeutic interventions is reduced but mortality rates are unaffected. The risk of intracranial or fatal haemorrhage from thrombolysis in PE is 1.8%.
A review of hyperkalaemia and its treatment contains some useful pearls: calcium gluconate is preferred to calcium chloride because of the latter’s tendency to cause tissue necrosis if extravasation occurs; hypertonic saline may reverse the ECG changes of hyperkalaemia, particularly in the presence of hyponatraemia; 10mg nebulised salbutamol lowers serum potassium by about 0.6 mmol/l, whereas 20mg lowers it by about 1.0 mmol/l – however up to 40% of patients are resistant to the hypokalaemic effects of salbutamol, for unknown reasons; the effects of insulin/dextrose are additive to those of salbutamol; sodium bicarbonate does not reduce potassium in dialysis-dependent kidney failure. Read the full article for more detailed discussion
Cardiologists have described a new ECG sign of acute proximal left anterior descending coronary artery occlusion: instead of the signature ST segment elevation, the ST segment showed a 1-3 mm upsloping ST segment depression at the J-point in V1-V6 that continued into tall, positive, symmetrical T waves. In most patients there was also a 1-2 mm St elevation in AVR. These changes were seen in 30 of 1532 (2.0%) of anterior AMI patients. A recognition of this pattern is essential for ensuring these patients receive early reperfusion therapy.
Here’s the latest update of literature relevant to what we do. Don’t get stressed if you don’t get round to reading all the original articles – reading the regular summaries should soothe your conscience and remove any nagging worries that you might be missing something big out there.
Critical care and retrieval
We all assume obese patients do badly on intensive care, but body fat may confer a survival advantage in critical illness. A study and editorial in Intensive Care Medicine add to the ‘large body’ of literature showing the optimal BMI for surviving critical illness is probably much higher than normally assumed, as adipocytes perform a number of protective functions including an immunomodulatory role.
A meta-analysis of six RCTs tells us that prophylactic administration of steroids in multidose regimens before planned extubation reduces the incidence of laryngeal oedema after extubation and the consequent reintubation rate in adults, with few adverse events. The accompanying editorial suggests a prudent approach might be to limit use to those patients at greatest risk of post-extubation stridor. Risk factors include female sex, short stature, trauma, and prolonged intubation. Laryngeal oedema may be predicted by deflating the cuff and demonstrating a leak of <18% http://www.bmj.com/cgi/content/abstract/337/oct20_1/a1841
For those of you following the etomidate story, a small nonblinded RCT in trauma patients comparing etomidate with fentanyl/midazalom is the first study to couple adverse clinical endpoints with depressed adrenocortical function. Not an issue in Australia of course, but there are enough Americans and Brits for this to give the willies to. http://www.ncbi.nlm.nih.gov/pubmed/18784570
So you’re at a primary where a patient is trapped under a bus and just the legs are sticking out. Tempted to attach the Zoll to the lower limbs for Sats and BP? In normal subjects the mean NIBP at the calf or ankle is very similar to that at the arm, whereas the systolic will be a bit off. Now your obs chart needn’t look incomplete even if your patient does.
Ever been taught a simple way of predicting mortality from burns based on age and total body surface area burned (BSAB)? Examples include if age + BSAB > 75, there is a >50% probability of death. Well now there’s a complicated one but it has a catchy acronym: The FLAMES score (Fatality by Longevity, APACHE II score, Measured Extent of burn, and Sex) was derived and (retrospectively) validated. The authors argue that a new more accurate predictive tool is needed because burns mortality has improved over the last few decades as a result of better management of burn shock, use of more effective topical antimicrobials, better systemic antibiotics, organization of regional burn units, earlier excision, and alternative measures for wound closure. Clearly this is tool for hospital use, catches on remember you heard it here first.
More info this month on detection of intracranial hypertension by sonographic optic nerve sheath diameter measurement, this time in patients undergoing ICP monitoring. The take home messages: optic nerve sheath diameter correlates better than optic nerve diameter with ICP, and a small ONSD probably means ICP isn’t raised. I’m not selling this very well am I?
A nice example of an international collaborative pre-hospital research trial is VITRIS (Vasopressin In refractory TRaumatic HemorrhagIc Shock), being studied by a network of 40 EMS helicopters in Austria, Germany, Switzerland, The Netherlands. The rationale? To maintain coronary and cerebral perfusion pressures and minimise subdiaphragmatic bleeding in patients who would otherwise bleed out and arrest before getting to a hospital trauma team. This thinking is supported by successful animal studies, all further explained in the uploaded article.
Trial homepage: http://www.vitris.at/frameset.htm
Further data to support a liberal FFP and Platelet transfusion strategy in trauma is supplied by Vanderbilt University Medical Centre where they retrospectively evaluated their ‘Trauma Exsanguination Protocol’ (only in America… ). 30 day mortality was significantly better with FFP:RBC ratios > 2:3 and Plt:RBC ratios > 1:5. Nice to have civilian data to compare with the controversial and scarely achievable military 1:1:1 recommendations.
There’s another couple of papers to add to the pre-hospital intubation pile (thanks to Mark Newcombe for these). The first paper shows that air medical teams find it harder to effect advanced airway interventions inside the aircraft compared with on scene, and the second takes an interesting look at the effect of out of hospital intubation (OOH-ETI) on outcome when related to distance from hospital . At all distances OOH-ETI was associated with worse outcomes unless patients were transported by helicopter. Take home message? Intubation bad, helicopters good – or perhaps the RSI delivered by experienced helicopter teams provides a survival benefit in salvageable patients (as opposed to patients dead enough to be intubated without drugs). Take a look for yourself and see if you can make sense of it!
First paper: http://www.ncbi.nlm.nih.gov/pubmed/18924006
Second paper: http://www.ncbi.nlm.nih.gov/pubmed/18924009
You attend a motor vehicle collision and the driver’s airbag has deployed. Which part of the body is most likely to be injured by the airbag and its housing? The answer is the upper limbs , particularly forearm fractures. The risk is maximised when the forearm crosses the middle of the steering wheel, for example the left forearm when turning right. As pre-hospital specialists, you can sleep soundly at night smugly reassured that no-one else knows this sort of thing.
And on the horizon….
A supplement to November’s Critical Care Medicine contains a glimpse of what might be to come in the field of cardiopulmonary resuscitation: animal studies demonstrate the possible benefit of head cooling during CPR, infusion of bone marrow stem cells to facilitate neurological repair post-resuscitation, and replacing conventional chest compressions with electrical stimulation of thoracic cage musculature. Perhaps the most likely of the proposed interventions to reach clinical practice in the shorter term is the impedence threshold device, which appears to contribute to improved outcomes in both piglets and humans, although it has been around for a few years now without catching on.
Recent gems from the literature that we could use or should know about:
Pre-hospital Care and Trauma
There have been recent concerns expressed about the possibility of FAST scanning by our retrieval team prolonging scene times, but what about on board the helicopter in flight? Can it be done? Would the results be accurate? Looks like our counterparts in South Australia have answered the question
If anyone has full text online access to the journal Injury, please let me in!
A dilemma we sometimes face: big trauma mechanism, but the patient seems fine. Do we immobilise? Do we give oxygen? Do we take to a trauma centre? Well here’s some Australian evidence that supports what we’ve known inside all along: mechanism alone does not usefully predict major injury in patients whose physiology and physical exam are normal
Identifying raised ICP using ultrasound of the eyes: This technique has been known about for a while but the evidence base hasn’t been strong. A recent Indian study adds further weight to the conclusions of this year’s BestBet on the topic: that there is a correlation between raised ICP and an optic nerve sheath diameter greater than 5mm. Likely to change our practice in pre-hospital and retrieval work? You decide!
Optic nerve ultrasound http://www.ncbi.nlm.nih.gov/pubmed/18325519
Cardiovascuar Critical Care
AHA/ACC guidelines for STEMI – implications for emergency medicine practice. This helpful summary provides a useful update as well as guidance for when particular procedures and drugs are indicated. Could be useful for retrieval practice, for example in assessing the appropriateness of a request to transfer a patient for rescue PCI.
Heart failure therapy – out with the old, in with the new: Morphine’s role in acute heart failure has been questioned for a while now. This article from New Zealand summarises what’s known. Take home message: don’t use it as a heart failure treatment – it doesn’t work and could be harmful.
What about CPAP/BiPAP? We know that works right? The most solid evidence to date – a multicentre RCT – says nope! Outcomes are the same as ‘medical’ therapy, other than a small difference in patient-reported dyspnoea. Nice to know we don’t need to transport heart failure patients on NIV now – fix ‘em medically or intubate them.
So gimme something that works for heart failure!! Okay, but you’re not going to like it……Ultrafiltration seems to work better than diuretics, with a lasting benificial effect on the hormonal components of heart failure. A bit fiddly at the moment because it requires a similar set up to haemofiltration (central access, ICU nurses, a haemofilter). From a retrieval point of view let’s hope it doesn’t catch on Australia until the newer peripheral access devices become available.
On the subject of central venous access, there are some things that will improve your chances of hitting the femoral vein : reverse Trendenlberg position, Valsalva maneouvre, or pushing on the abdomen in the RUQ. Combining them improves things further.
Want a useful update on evidence-based management of GI bleeding? This one is brand new and fits in your pocket – from the Scottish Intercollegiate Guidelines Network (SIGN)
That’s it for now….enjoy!!