Monthly Archives: December 2012

All Updates, ICU, PHARM, Resus, Trauma

London Calling – part 2

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Notes from Days 2 & 3 of the London Trauma Conference
Day 2 of the LTC was really good. There were some cracking speakers who clearly had the ‘gift’ when it comes to entertaining the audience. No death by PowerPoint here (although it seems Keynote is now the presentation software of choice!). The theme of the day was prehospital care and major incidents.
The golden nuggets to take away include: (too many to list all of course)

  • ‘Pull’ is the key to rapid extrication from cars if time critical from the Norweigan perspective. Dr Lars Wik of the Norweigen air ambulance presented their method of rapid extrication. Essentially they drag the car back on the road or away from what ever it has crashed into to control the environment and make space (360 style). They put a paramedic in the car whilst this is happening. They then make a cut in the A post near the roof, secure the rear of the car to a fire truck or fixed object with a chain and put another chain around the lower A post and steering wheel that is then winched tight. This has the effect of ‘reversing’ the crash and a few videos showed really fast access to the patient. The car seems to peel open. As they train specifically for it, there doesn’t seem to be any safety problems so far and its much quicker than their old method. I guess it doesnt matter really how you organise a rapid extrication method as long as it is trained for and everyone is on the same page.
  • Dr Bob Winter presented his thoughts on hangings – to date no survivor of a non-judicial hanging has had a C-spine injury, so why do we collar them? Also there seems no point in cooling them. All imaging and concern for these patients should be based on the significant soft tissue injury that can be caused around the neck.
  • Drownings – if the patient is totally submerged probably reasonable to search for 30mins in water that is >6 degrees or 90mins if <6 degrees. After that it becomes a body recovery (unless there is an air pocket or some exceptional circumstance). Patients that have drowned should have early ventilatory support if they show any signs of resp distress.
  • Drs Julian Thompson and Mark Byers reassured us on a variety of safety issues at major incidents. It seems the risk to rescuers from secondary bombs at scene is low. Very few terrorist attacks world wide, ever, have had secondary devices so rescuers should be reassured (a bit). Greatest risk to the rescuer, like always, are the silly simple things that are a risk every day, like tripping over your own feet! With reference to chemical incidents, simple PPE seems to be sufficient for the vast majority of incidents, even fairly significant chemical ones, all this mucking about in full air tight suits is probably pointless and means patients cant be treated (at all). This led to the debate of how much risk should we, as rescue staff, accept? Clearly there are no absolute answers but minimising all risk to the rescuer is often at conflict with your ability to rescue. Where the balance should lie is a matter for organisations and individuals I guess.
  • Sir Prof Keith Porter also gave us an update on the future of Prehospital emergency medicine as a recognised medical specialty. As those in the know, know, the specialty has been recognised by the GMC and the first draft of trainees are currently in post. More deaneries will be following suit soon to begin training but it is likely to take some time to build up large numbers of trained specialists. Importantly for those of us who already have completed our training there will be an option to sub specialise in PHEM but it will involve undertaking the FIMC exam. Great, more exams – see you there.

 
Day 3 – Major trauma
The focus of day 3 was that of damage control. Damage control surgery and damage control resucitation. We had indepth discussions about how to manage pelvic trauma and some of the finer points of trauma resuscitation.
Specific points raised were:

  • Pelvic binders are great and can replace an ex fix if the abdomen needs opening to fix a spleen for example.
  • You can catheterise patients with pelvic fractures (one gentle try).
  • Most pelvic bleeds are venous which is why surgeons who can pack a pelvis is better than a radiologist who can mainly only treat arterial bleeds.
  • Coagulopathy in trauma is not DIC and is probably caused by peripheral hypoperfusion.
  • All the standard clotting tests that we use (INR etc) are useless and take too long to do. ROTEM or TEG is much better but still not perfect.

Also, as I am sure will please many – pressure isn’t flow so dont use pressors in trauma!
 
 


Chris Hill is an emergency and prehospital care physician based in the United Kingdom

All Updates, ICU, PHARM, Resus, Trauma, Ultrasound

London Calling!!

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Notes from Day 1 of the London Trauma Conference
I’ve always fancied trying my hand at journalism so when this opportunity to cover the London Trauma Conference (LTC) presented itself how could I resist? The LTC is well established now running into its sixth year. So what little gems does it have left to offer?
The Air Ambulance Symposium opened the conference with strong representation from Norway.
Dr Marius Rehn presented a thought provoking talk on pre-hospital trauma triage. Pragmatically there will always be a proportion of patients that are mistriaged. So is under triage worse than over triage? It depends on whose point of view you take. If you’re the trauma victim then under triage is your greatest fear. But as clinicians we display loyalty bias (preferential consideration for our current patient over those we have no involvement with) which leads to over triage. The consequences are usually unseen as they manifest in other areas of the health system – studies have demonstrated a detrimental effect in cardiac patients arriving in units where a trauma patient is treated concurrently. Commonly under triaged are older patients that have low mechanism falls and children involved in RTC’s are over triaged. Triage protocols aren’t perfect but those based on physiology and anatomy are the best; even better still an experienced clinician (physicians better than paramedics) and in the future we should think about using lactate clearance.
I have never needed any convincing that ultrasound has a role in pre-hospital care. However Dr Nils Petter Oveland presented some of his research (due for publication next year) which reinforces this belief. He studied chest ultrasound for the detection of pneumothoraces. Plain radiography interpreted by a consultant radiologist can detect a 500ml pneumothorax; ultrasonography can detect a mere 50ml. Using pig models he demonstrated a linear relationship between the volume of the pneumothorax and the sternal – lung point distance (lung point = where the lung edge remains in contact with the pleura). Practically how can we use this? A small pneumothorax may be detected by ultrasound but have no clinical consequence. Prior to aero medical transfer the lung point can be marked and if clinical deterioration occurs en route repeat US can accurately determine an increase in pneumothorax volume and guide treatment. Genius!
Prof Hans Morten Lossius provided a convincing argument for pre-hospital stroke thrombolysis. If you believe in this treatment, then it is more efficacious the sooner it is delivered (see photo). So why are we aiming for a thrombolysis time that is suboptimal? The thrombolysis times for a central Norwegian hospital were in the region of 3.5hrs, this reduced to 2.5hrs with rapid transportation. Approaching the problem from a different angle they trialled pre-hospital management with a mobile unit (CT scanner + neuroradiologist + neurologist) reducing time to thrombolysis to 72min (Lancet Neurology 2012, Walter). The next step is a multicentre RCT comparing standard treatment against a mobile CT + pre-hospital team with telemedical links to the Stroke centre……..
The Keynote address from Dr Gareth Davies took a look at the past and then a look to the future – the focus remained the same; providing the intervention patients need when they need it! Could this lead us into a future of Resuscitative Emergency Balloon Occlusion of the Aorta (REBOA) or Emergency Preservation Resuscitation (EPR) or emergency pre-hospital burr holes? Only time will tell.
Dr Steven Solid presented a double bill on patient safety. Admission to hospital is a high risk activity (as risky as bungee jumping!). Patient harm in aviation occurs 2 per 1000 flights. Only 25% were aviation related; mostly they are communication or equipment failures. He suggests medical line checks and team simulation training.

Dr Anne Weaver finished the first day with the story of her quest to get pre-hospital blood onto London HEMS to compliment the pre-hospital haemostatic resuscitation strategy they have for exsanguinating haemorrhage (tranexamic acid, prothrombin complex concentrate (for rapid warfarin reversal), POC INR machine, Buddy Lite™ blood warmers). Initial observations after the first six months are that ROSC is achieved more frequently in traumatic cardiac arrests although it’s too early to comment on mortality benefit. But this isn’t then end of the story – the next challenge is fresh frozen plasma.

All Updates, ICU, Kids, PHARM, Resus

Reassurance: difficult laryngoscopy in children remains rare

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I was taught a useful principle by a paediatric anaesthetist 10 years ago which has proven true in my experience and has contributed to keeping me calm when intubating sick kids. Unlike adults, in whom difficulty in intubation can often be unexpected, the vast majority of normal looking children are easy to intubate, and the ones who are difficult usually have obvious indicators such as dysmorphism.
This appears to be supported by recent evidence: in a large retrospective series of 11.219 anaesthesia patients, the overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was only 1.35%, although was much higher in infants less than one year compared with older children. This low percentage is in the same ball park as two other paediatric studies. Besides younger age, their database suggested underweight, ASA III and IV physical status and, if obtainable, Mallampati III and IV findings as predictors for difficult laryngoscopy. The authors point out:

“…the oromaxillofacial surgery department with a high proportion of cleft palate interventions and pediatric cardiac surgery contributed substantially to the total number of difficult laryngoscopies. In patients undergoing pediatric cardiac surgery, a possible explanation for the higher incidence of CML III/IV findings might be that some congenital heart defects are associated with chromosomal anomalies like microdeletion 22q11.2 syndrome. This syndrome is also associated with extracardiac anomalies like cranio-facial dysmorphism“

Take home message: As a very rough rule of thumb to illustrate the difference between the ease/difficulty of laryngoscopy between adults and kids, I think it’s fair to say grade III or IV views occur in about 10% of adults but only about 1% of children.

Incidence and predictors of difficult laryngoscopy in 11.219 pediatric anesthesia procedures
Paediatr Anaesth. 2012 Aug;22(8):729-36
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OBJECTIVE: Difficult laryngoscopy in pediatric patients undergoing anesthesia.

AIM: This retrospective analysis was conducted to investigate incidence and predictors of difficult laryngoscopy in a large cohort of pediatric patients receiving general anesthesia with endotracheal intubation.

BACKGROUND: Young age and craniofacial dysmorphy are predictors for the difficult pediatric airway and difficult laryngoscopy. For difficult laryngoscopy, other general predictors are not yet described.

METHODS: Retrospectively, from a 5-year period, data from 11.219 general anesthesia procedures in pediatric patients with endotracheal intubation using age-adapted Macintosh blades in a single center (university hospital) were analyzed statistically.

RESULTS: The overall incidence of difficult laryngoscopy [Cormack and Lehane (CML) grade III and IV] was 1.35%. In patients younger than 1 year, the incidence of CML III or IV was significantly higher than in the older patients (4.7% vs 0.7%). ASA Physical Status III and IV, a higher Mallampati Score (III and IV) and a low BMI were all associated (P < 0.05) with difficult laryngoscopy. Patients undergoing oromaxillofacial surgery and cardiac surgery showed a significantly higher rate of CML III/IV findings.

CONCLUSION: The general incidence of difficult laryngoscopy in pediatric anesthesia is lower than in adults. Our results show that the risk of difficult laryngoscopy is much higher in patients below 1 year of age, in underweight patients and in ASA III and IV patients. The underlying disease might also contribute to the risk. If the Mallampati score could be obtained, prediction of difficult laryngoscopy seems to be reliable. Our data support the existing recommendations for a specialized anesthesiological team to provide safe anesthesia for infants and neonates.

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All Updates, ICU, Kids, PHARM, Resus, Trauma

Transtracheal airways in kids. Well, pigs' kids anyway

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Ever had to do a surgical airway in a child? Thought not. They’re pretty rare. Bill Heegaard MD from Henepin County Medical Center taught me a few approaches (with the help of an anaesthetised rabbit) which really got me thinking. It’s something I’d often trained for in my internal simulator, and I even keep the equipment for it in my house (listen out for an upcoming podcast on that). Research and experience has demonstrated that open surgical airway techniques are more reliable than transtracheal needle techniques in adults, but what about kids, in whom traditional teaching cautions against open techniques?

Australian investigators who were experienced airway proceduralists evaluated transtracheal needle techniques using a rabbit model (an excellent model for the infant airway). Their success rate was only 60% and they perforated the posterior tracheal wall in 42% of attempts. Of 13 attempts to insert a dedicated paediatric tracheotomy device, the Quicktrach Child, none were successful(1) (they did not use the Quicktrach Infant model as it is not available in Australia).

Danish investigators used fresh piglet cadavers weighing around 8 kg to assess two transtracheal cannulas, in which they achieved success rates of 65.6% and 68.8%(2). There was also a very high rate of posterior tracheal wall perforation. Using an open surgical tracheostomy technique, they were successful in 97% of attempts. These were also experienced operators, with a median anaesthetic experience of 12.5 years.
Their tracheotomy technique was nice and simple, and used just a scalpel, scissors, and surgical towel clips. Here’s their technique:

Simple tracheotomy procedure described by Holm-Knudsen et al

  1. Identify larynx and proximal trachea by palpation
  2. Vertical incision through the skin and subcutaneous tissue from the upper part of larynx to the sternal notch
  3. Grasp strap muscles with two towel forceps and separate in the midline
  4. Palpate and identify the trachea (palpate rather than look for tracheal rings, as in a live patient one would expect bleeding to obscure the view)
  5. Stabilise the trachea by grasping it with a towel forceps
  6. Insert sharp tip of the scissors between two tracheal rings and lift the trachea anteriorly to avoid damage to the posterior wall
  7. Cut vertically in the midline of the trachea with the scissors – they chose to use the scissors to cut the tracheal rings to facilitate tube insertion
  8. Insert the tracheal tube

Using ultrasound and CT to evaluate comparative airway dimensions, the authors concluded that the pig model is most useful for training emergency airway management in older children aged 5–10 years.
Why were they doing a tracheotomy rather than a cricothyroidotomy? Reasons given by the authors include:

  • The infant cricothyroid membrane is very small
  • Palpation of the thyroid notch may be hindered by the overlying hyoid bone
  • The mandible may obstruct needle access to the cricothyroid membrane given the cephalad position in the neck of the infant larynx.

From an emergency medicine point of view, there are a couple of other reasons why we need to be able to access the trachea lower than the cricothyroid membrane. One is fractured larynx or other blunt or penetrating airway injury where there may be anatomical disruption at the cricothyroid level. The other situation is foreign body airway obstruction, when objects may lodge at the level of the cricoid ring which is functionally the narrowest part of the pediatric upper airway. Of course, alternative methods might be considered to remove the foreign body prior to tracheotomy, such as employing basic choking algorithms, and other techniques depending on whether you do or don’t have equipment.

Take home messages

  • Transtracheal airways in kids are so rare, we can’t avoid extrapolating animal data
  • Whichever infant or paediatric model is used, transtracheal needle techniques have a high rate of failure even by ‘experienced’ operators
  • The small size and easy compressibility of the airway probably contributes to this failure rate, including the high rate of posterior wall puncture
  • In keeping with adult audit data, open surgical techniques may have a higher success rate
  • Tracheotomy may be necessary rather than cricothyroidotomy in infants and children depending on clinical scenario and accessibility of anatomy
  • The stress and blood that is not simulated in cadaveric animal models will make open tracheotomy harder in a live patient, and so these success rates may not translate. However these factors do mean that whatever technique is used must be kept simple and should employ readily available and familiar equipment
  • Something to maintain control and anterior position of the anterior trachea wall should be used during incision and intubation of the trachea. The study reported here used towel clips; sutures around the tracheal rings may also be used (see image below)

I recommend you add ‘paediatric tracheotomy’ to the list of procedures you might need to do (if it’s not already there). Identify what equipment you would use and run the simulation in your head and in your work environment.
Have fun.

1. The ‘Can’t Intubate Can’t Oxygenate’ scenario in Pediatric Anesthesia: a comparison of different devices for needle cricothyroidotomy
Paediatr Anaesth. 2012 Dec;22(12):1155-8

BACKGROUND: Little evidence exists to guide the management of the ‘Can’t Intubate, Can’t Oxygenate’ (CICO) scenario in pediatric anesthesia.

OBJECTIVES: To compare two intravenous cannulae for ease of use, success rate and complication rate in needle tracheotomy in a postmortem animal model of the infant airway, and trial a commercially available device using the same model.

METHODS: Two experienced proceduralists repeatedly attempted cannula tracheotomy in five postmortem rabbits, alternately using 18-gauge (18G) and 14-gauge (14G) BD Insyte(™) cannulae (BD, Franklin Lakes, NJ, USA). Attempts began at the first tracheal cartilage, with subsequent attempts progressively more caudad. Success was defined as intratracheal cannula placement. In each rabbit, an attempt was then made by each proceduralist to perform a cannula tracheotomy using the Quicktrach Child(™) device (VBM Medizintechnik GmbH, Sulz am Neckar, Germany).

RESULTS: The rabbit tracheas were of similar dimensions to a human infant. 60 attempts were made at cannula tracheotomy, yielding a 60% success rate. There was no significant difference in success rate, ease of use, or complication rate between cannulae of different gauge. Successful aspiration was highly predictive (positive predictive value 97%) and both sensitive (89%) and specific (96%) for tracheal cannulation. The posterior tracheal wall was perforated in 42% of tracheal punctures. None of 13 attempts using the Quicktrach Child(™) were successful.

CONCLUSION: Cannula tracheotomy in a model comparable to the infant airway is difficult and not without complication. Cannulae of 14- and 18-gauge appear to offer similar performance. Successful aspiration is the key predictor of appropriate cannula placement. The Quicktrach Child was not used successfully in this model. Further work is required to compare possible management strategies for the CICO scenario

2. Emergency airway access in children – transtracheal cannulas and tracheotomy assessed in a porcine model
Paediatr Anaesth. 2012 Dec;22(12):1159-65

OBJECTIVES: In the rare scenario when it is impossible to oxygenate or intubate a child, no evidence exists on what strategy to follow.

AIM: The aim of this study was to compare the time and success rate when using two different transtracheal needle techniques and also to measure the success rate and time when performing an emergency tracheotomy in a piglet cadaver model.

METHODS: In this randomized cross-over study, we included 32 anesthesiologists who each inserted two transtracheal cannulas (TTC) using a jet ventilation catheter and an intravenous catheter in a piglet model. Second, they performed an emergency tracheotomy. A maximum of 2 and 4 min were allowed for the procedures, respectively. The TTC procedures were recorded using a video scope.

RESULTS: Placement of a transtracheal cannula was successful in 65.6% and 68.8% of the attempts (P = 0.76), and the median duration of the attempts was 69 and 42 s (P = 0.32), using the jet ventilation catheter and the intravenous catheter, respectively. Complications were frequent in both groups, especially perforation of the posterior tracheal wall. Performing an emergency tracheotomy was successful in 97%, in a median of 88 s.

CONCLUSIONS: In a piglet model, we found no significant difference in success rates or time to insert a jet ventilation cannula or an intravenous catheter transtracheally, but the incidence of complications was high. In the same model, we found a 97% success rate for performing an emergency tracheotomy within 4 min with a low rate of complications.