Category Archives: All Updates

Prehospital airway equipment on UK HEMS

Prehospital airway management on rescue helicopters in the United Kingdom
26 of 27 identified UK rescue helicopter bases responded to a questionnaire sent by German anaesthesiologists on the airway equipment they carried. The take home message is that there were some important gaps: not all carried equipment for establishing a surgical airway and not all had a means of capnometry. Pull your socks up guys the Germans are watching.
Anaesthesia. 2009 Jun;64(6):625-31

Trauma scissors vs the Rescue Hook

Trauma scissors vs the Rescue Hook, exposing a simulated patient: a pilot study
American military investigators compared traditional trauma scissors with the ‘rescue hook’ (a hooked knife with the cutting edge on the inside of the hook) in rapidly removing the clothes from a simulated casualty. An army desert combat uniform and boots were removed more quickly with the rescue hook, which was favoured by the combat medics employed in the study. We don’t have data on how it would work on denim, leather, or belts, but it looks pretty good. I just want to know if it’ll go through a sternum before I trade in my trauma scissors.
J Emerg Med. 2009 Apr;36(3):232-5

Fluid Flow Through Intravenous Cannulae

Published flow rates for cannulae are derived from a test in which fluid runs through a perfectly straight cannula into an open receptacle. Laminar flow is expected in such a model in which the Hagen-Poisseuille formula tells us that flow is proportional to the fourth power of the radius. In this study manufacturers’ published flow rates were compared with an artifical vein model. Hartmann’s flowed faster than Gelofusine. For all cannulas flow was less than the manufacturers’ published rates. Although the radius was the biggest determinant of flow rate, the fourth power could not be used, suggesting a mixture of laminar and turbulent flow. The addition of pressurised infusions increased the flow rate with increasing pressure. Although the vein model used has limitations, and many other factors may influence flow rate in the clinical setting, the authors’ conclusions are helpful:
While the effect of radius is less than commonly believed, it is still important. However, clinicians should be aware of the limitations of increasing radius and use other strategies to increase flow when needed. These could include use of pressure, choice of fluid to be infused, and using multiple cannulae in parallel.
Fluid flow through intravenous cannulae in a clinical model
Anesth Analg. 2009 Apr;108(4):1198-202

High BMI and frontal crashes

In adult patients injured in front impact motor vehicle collisions, the outcomes of obese patients with a Body Mass Index greater than 30 kg/m2 was compared with those less than 30 kg/m2. Obese patients were more likely to suffer a severe head injury from a frontal collision.
J Trauma. 2009 Mar;66(3):727-9
Traumatic Brain Injury After Frontal Crashes: Relationship With Body Mass Index

Tourniquets Revisited

A volunteer study showed that tourniquets were just as effective at occluding distal blood flow measured by doppler signal when placed below the elbow or knee compared with above those joints. A makeshift windlass tourniquet, a rubber tube tourniquet, and a blood pressure cuff were all effective. Digital ‘pressure point control’ failed to maintain control of brachial or femoral artery flow.
Tourniquets Revisited
J Trauma. 2009 Mar;66(3):672-5

ETCO2 all over the place in trauma

In 180 intubated trauma patients in the ED, there was little correlation between arterial carbon dioxide tension (PaCO2) and end-tidal carbon dioxide levels (ETCO2) (R2 = 0.277). In fact, in those patients ventilated to the ‘normal range’ of 35-40 mmHg (4.6-5.2 kPa), PaCO2 was over 50 mmHg 30% of the time. Slightly reassuring that in isolated brain injury the correlation was better (r2 = 0.52)
The Utility of Early End-Tidal Capnography in Monitoring Ventilation Status After Severe Injury
J Trauma. 2009 Jan;66(1):26-31

Blood product ratios and survival bias

Haemostatic resuscitation of trauma patients, using high ratios of fresh frozen plasma (FFP) to packed red cells (PRBC), is growing in popularity as a result of military experience. Few data support the practice in civilian trauma. It is possible that some of the demonstrated mortality benefit is a result of survival bias: it takes time to obtain FFP, by which time severely injured patients may be dead. Therefore, those that receive large ratios of FFP:PRBC must have survived long enough to receive it. In other words FFP doesn’t lead to survival, but survival leads to FFP. Some evidence in favour of this explanation is provided on a study of 134 patients in the Journal of Trauma. Reanalysing data to correct for survival bias made an apparently significant survival benefit from high FFP:PRBC ratios go away. An interesting paper, although unlikely to dissuade us from paying attention to coagulopathy in trauma. I suspect the debate on optimal blood product resuscitation will be around for a while.
The Relationship of Blood Product Ratio to Mortality: Survival Benefit or Survival Bias?
J Trauma. 2009 Feb;66(2):358-62

Sodium lactate for raised ICP

Lactate may be an important metabolic substrate for injured brain and sodium lactate may have beneficial effects on cerebral oedema and cerebral blood flow. Sodium lactate was compared with 20% mannitol in severely brain injured patients with cranial hypertension in a randomised controlled trial. Sodium lactate was more likely to lower ICP, and to have a sustained effect on ICP. A nonsignificant improvement in one year outcome was seen with sodium lactate, although the study was not powered for this endpoint. These promising findings should prompt a larger multicentre study.
Sodium lactate versus mannitol in the treatment of intracranial hypertensive episodes in severe traumatic brain-injured patients
Intensive Care Med. 2009 Mar;35(3):471-9

Paramedics control space

Paramedics practice ‘‘in the street’’ and perform in ‘‘a context rife with chaotic, dangerous, and often uncontrollable elements with which hospital-based practitioners need not contend’ We knew that, but what isn’t known is how more experienced or expert paramedics differ from novices in scene management. This qualitative study involving interviews of 24 paramedics describes the ‘space control theory’ – how paramedics establish control over their immediate workspace to effectively deliver patient care. It’s not big on detail, but at least this paper documents for hospital-based ambulance medical advisors that there is more to paramedicine than purely clinical factors, which is why insistence on hospital-derived clinical treatment algorithms might sometimes be inappropriate in the field. I’ve emailed the author for more details.
Introduction to the ‘‘space-control theory of paramedic scene management’’
Emerg Med J. 2009 Mar;26(3):213-6

Pre-hospital arterial lines

Arterial lines in the field? You’ve got to be nuts, or…..French! Yep, the SAMU boys and girls put in 94 arterial lines in pre-hospital cases over two years, and found big differences between invasive and non-invasive arterial pressures in systolic and diastolic pressures. What about mean pressures though, which we’d expect to be more closely correlated? They didn’t say. An interesting paper, but I don’t think I can use it.
Emerg Med J. 2009 Mar;26(3):210-2
Invasive arterial blood pressure monitoring in an out-of-hospital setting: an observational study