Awake intubation

I had some fun today getting intubated.

We used the Ambu aScope 2 and the Greater Sydney Area HEMS equipment and approach to airway management. I didn’t receive an antisialogogue or any analgesia or sedation.

The big learning point for me was how hard it was to anaesthetise the posterior part of my nasal cavity and nasopharynx. I thought the worst part would be any stimulation of my vocal cords or trachea with lidocaine or instrumentation, but this really was fine. Nebulised 2% lidocaine (the strongest concentration we have), atomised lidocaine (using a mucosal atomiser), and co-phenylcaine spray weren’t sufficient. I can see why people use pastes or gel to maintain mucosal contact while the lidocaine takes effect, but we don’t have those (yet). The best solution came from hooking up oxygen tubing to an iv cannula via a three way tap. Oxygen was run through at 2 l/min and lidocaine injected via the the three way tap. This enabled an atomised spray to be directed right onto the area concerned, and made the insertion of the nasotracheal tube more tolerable – although still unpleasant.

The fact I could be intubated awake with reasonable topicalisation suggests most patients should tolerate it perhaps after even an analgesic dose of ketamine, eg. 30-40 mg in an adult. I suspect full dissocation would not be required, which is good for cooperation (“stick your tongue out sir”). I appreciate there are better agents, such as remifentanil or dexmedetomidine, but my area of interest is the retrieval setting – where I have neither the luxury of using these agents nor that of calling for anaesthetic back up.

Thanks to HEMS physicians Emily Stimson, Nirosha De Zoysa, Felicity Day, Chloe Tetlow, and Fergal McCourt for making it fun and safe.

Here’s the video:

Twitter has been helpful in gathering some advice, particularly from @DocJohnHinds:

Another argument for ED thoracotomy

A team from Los Angeles (including the great Kenji Inaba) has published a study on penetrating cardiac wounds in the pediatric population[1]. This is one of the largest studies on this thankfully rare event.

The outcome was poor which may be due to the high proportion of patients arriving at hospital without signs of life (SOL).

What I like about the paper is the discussion of their liberal policy for the use of resuscitative ED thoracotomy:

…we do not rely heavily on prehospital data regarding the precise timing of loss of SOL. Thus, at the discretion of the attending trauma surgeon, every penetrating injury to the chest with SOL lost during patient transport will be considered for ED thoracotomy.

In cases when a perfusing cardiac rhythm is regained, the patient will receive all operative and critical care support as standard of care. If the patient progresses to brain death, aggressive donor management will be implemented in accordance with consent obtained by the organ procurement organization.

In a recent publication, we observed two pediatric patients who underwent ED thoracotomy that subsequently became organ donors after brain death was declared [2]. A total of nine organs were recovered for transplantation. This contemporary outcome measure is of paramount importance in the current era of significant organ shortage.

When such aggressive resuscitative procedures are attempted on arrested trauma patients, there is a temptation to justify inaction on the grounds of futility or the risk of ‘creating a vegetable’. This paper reminds us that other outcome benefits may arise from attempted resuscitation even if the patient does not survive.

These benefits include the saving of other lives through organ donation. In addition to this, there is the opportunity for family members to be with their loved one on the ICU, to hold their warm hand for the last time, to hear the news broken by a team they have gotten to know and trust, to enact any spiritual or religious rites that may provide a source of comfort and closure, and to be there during withdrawal of life sustaining therapies after diagnosis of brain stem death. That will never be pleasant, but on the bleak spectrum of parental torture it may be better than being told the devastating news in the ED relatives’ room by a stranger they’ve never met but will remember forever.

The ED thoracotomy may at the very least remove any doubt that everything that could have been done, was done.

1. Penetrating cardiac trauma in adolescents: A rare injury with excessive mortality
Journal of Pediatric Surgery (2013) 48, 745–749
Abstract

2. Organ donation: an important outcome after resuscitative thoracotomy
J Am Coll Surg. 2010 Oct;211(4):450-5
Abstract

Cricoid can worsen VL View

It is known that cricoid pressure can hinder laryngoscopic view of the cords during direct laryngoscopy. Using a Pentax-AWS Video laryngoscope, these authors have demonstrated that cricoid pressure can also worsen glottic view during video laryngoscopy.

Videographic Analysis of Glottic View With Increasing Cricoid Pressure Force
Ann Emerg Med. 2013 Apr;61(4):407-13
Abstract

Endovascular stroke treatment

Two randomised controlled trials have been published which compare endovascular stroke treatments with intravenous tPA. Both the American Interventional Management of Stroke (IMS) III trial (1) and the Italian SYNTHESIS Expansion trial (2) had Modified Rankin Scores as their primary endpoint. No significant differences in this outcome or in mortality or intracranial haemorrhage rates were found in either trial, and IMS III was terminated early due to futility.

A third trial, from North America, called MR RESCUE, randomised patients within 8 hours after the onset of large vessel, anterior-circulation strokes to undergo mechanical embolectomy or receive standard care(3). No clinical outcome differences were demonstrated.

An accompanying editorial (4) draws the following conclusion:

“The IMS III and SYNTHESIS Expansion studies show that intravenous thrombolysis should continue to be the first-line treatment for patients with acute ischemic stroke within 4.5 hours after stroke onset, even if imaging shows an occluded major intracranial artery. Beyond 4.5 hours, the MR RESCUE trial does not provide data supporting the use of endovascular treatment in patients with an ischemic penumbra of any size.”

Many might argue that showing endovascular treatment is equivalent to thrombolysis just means endovascular treatment doesn’t work, because a significant proportion of the emergency medicine community views this as the correct interpretation of a thorough analysis of the stroke thrombolysis literature.

1. Endovascular Therapy after Intravenous t-PA versus t-PA Alone for Stroke
NEJM Feb 8, 2013 Full Text Link

2. Endovascular Treatment for Acute Ischemic Stroke
NEJM Feb 8, 2013 Full Text Link

3. A Trial of Imaging Selection and Endovascular Treatment for Ischemic Stroke
NEJM Feb 8, 2013 Full Text Link

4.Endovascular Treatment for Acute Ischemic Stroke — Still Unproven
NEJM Feb 8, 2013 Full Text Link

Lifting the Fogg on ED Intubaton

Fellow retrieval specialist and Royal North Shore Hospital emergency physician Dr Toby Fogg and coauthors have published their audit of intubations in an Australian Emergency Department(1). More important than the results themselves is that the process of monitoring ones practice inevitably leads to improvements. For example, at Toby’s institution an intubation checklist has been introduced since the audit began. Other Australasian EDs are encouraged to participate using the free resources at airwayregistry.org.au.

Recently we have also seen the publication of Korean registry data on paediatric intubations performed in 13 academic EDs over 5 years(2), in which first pass success rates (overall 67.6%) were higher with emergency physicians compared with paediatricians. Interestingly, a rapid sequence intubation technique was only used in 22.4% of intubations, which was more likely to be used by emergency physicians and was associated with a greater likelihood of first pass success.

This relatively low first pass success rate is reminiscent of the American study published in September(3) which raised some eyebrows with its 52% first pass intubation success rates in a paediatric ED, and which also showed that attending-level providers were 10 times more likely to be successful on the first attempt than all trainees combined. Possible reasons for such a low first pass success rate compared with adult registry data include the rigorous video analysis method used, or perhaps more likely that paediatric emergency subspecialists are exposed to fewer critical procedures, resuscitations, and intubations than their general emergency medicine counterparts(4).

As a specialty we must continue to seek to do better, and I salute all these brave authors who are telling it like it is. Particularly with children, whose airways are relatively easy, we have to develop the training, preparation, supervision, monitoring and feedback to aim for as high a success rate as possible.

1. Prospective observational study of the practice of endotracheal intubation in the emergency department of a tertiary hospital in Sydney, Australia
Emerg Med Australas. 2012 Dec;24(6):617-24
Click to read abstract

2. The factors associated with successful paediatric endotracheal intubation on the first attempt in emergency departments: a 13-emergency-department registry study
Resuscitation. 2012 Nov;83(11):1363-8
Click to read abstract

3.Rapid sequence intubation for pediatric emergency patients: higher frequency of failed attempts and adverse effects found by video review.
Ann Emerg Med. 2012 Sep;60(3):251-9
Click to read abstract

4. A is for airway: a pediatric emergency department challenge.
Ann Emerg Med. 2012 Sep;60(3):261-3

Which pelvic compression device is best?

Two popular pelvic compression devices are the SAM Pelvic Sling II and the T-POD®.

In a direct comparison 50 health care volunteers secured both devices correctly 100% of the time.

The SAM Pelvic Sling II was quicker to apply, but participants preferred the T-POD®.

The authors conclude that very little separates the devices.

Pelvic circumferential compression devices (PCCDs): a best evidence equipment review
Eur J Trauma Emerg Surg (2012) 38:439–442
Click for abstract

What happened to HIFU?

High intensity focused ultrasound (HIFU) was hailed as the ‘surgery of the future’ a few years ago(1). As it’s now the future, where is it?

HIFU uses ultrasound to increase the heat within tissues at a specific area, causing local necrosis and cautery without injuring surrounding tissues. It is used to treat some cancers, but has shown promise in haemorrhage control. In animal studies it reduced or stopped bleeding in liver(2), spleen(3), and vascular injuries(4).

It has been proposed to offer a promising method for hemorrhage control in both civilivan and miltary trauma(5). Automated systems have been developed and tested that identify bleeding using Doppler ultrasound techniques that then allow targeting of the HIFU beam to the bleeding tissue(6). The United States Army has identified the need for a such systems and has designed a remotely operated robotic haemostatic system to save lives of soldiers. This was presented in 2006(7).

I would love to know where we are with this technology, and why nothing seems to have appeared about it in the literature for the last few years. If you have any information, please fill us in via the comments box.

1. High intensity focused ultrasound: surgery of the future?
Br J Radiol. 2003 Sep;76(909):590-9 Full text

2. Liver hemostasis using high-intensity focused ultrasound
Ultrasound Med Biol. 1997;23(9):1413-20

3. Control of splenic bleeding by using high intensity ultrasound
J Trauma. 1999 Sep;47(3):521-5

4. Hemostasis of punctured blood vessels using high-intensity focused ultrasound
Ultrasound Med Biol. 1998 Jul;24(6):903-10

5. Hemorrhage control using high intensity focused ultrasound
Int J Hyperthermia. 2007 Mar;23(2):203-11

6. Focused ultrasound: concept for automated transcutaneous control of hemorrhage in austere settings.
Aviat Space Environ Med. 2009 Apr;80(4):391-4

7. Remotely Operated Robotic High Intensity Focused Ultrasound (HIFU) Manipulator System for Critical Systems for Trauma and Transport (CSTAT)
Presented at the IEEE Ultrasonics Symposium, October 3-6, 2006, Vancouver, Canada – Full Text Here

Perimortem Caesarean Delivery: Late is Better than Not

“To date, approximately one-third of the women who die during pregnancy remain undelivered at the time of death”

Guidelines recommend cardiac arrest in pregnant women beyond 20 weeks gestation should be treated with perimortem caesarean delivery (PMCD) commenced within 4 minutes of arrest and completed within 5. These time intervals come from two papers, neither of which is current or used robust review methodology.

To address this, an up-to-date fairly comprehensive review was undertaken of published cases of maternal cardiac arrests occurring prior to delivery. The primary outcome measures were maternal and neonatal survival to hospital discharge and the relationship between PMCD and this outcome.

The Arrests

94 cases were included in the final analysis.Most pregnancies were singleton (90.4%, n = 85) with an average gestational age at the time of the arrest of 33 ± 7 weeks (median 35, range 10–42).

The most common causes of arrest were trauma, maternal cardiac problems, severe pre-eclampsia and amniotic fluid embolism, together comprising about 70% of arrests; two thirds occurred in hospital.

The Outcomes

Overall, return of spontaneous circulation (ROSC) was achieved more often than not (60.6%) and overall survival to hospital discharge was 54.3%

Only 57 cases (75%) reported the time from arrest to delivery; the average time was 16.6 ± 12.5 min (median 10, range 1–60), with only 4 cases making it under the advocated 4-min time limit.

Timing of PMCD and Maternal Survival

In cases undergoing PMCD the average time elapsing from arrest to PMCD was significantly different between surviving (27/57) and non-surviving (30/57) mothers [10.0 ± 7.2 min (median 9, range 1–37) and 22.6 ± 13.3 min (median 20, range 4–60) respectively (p < 0.001, 95%CI 6.9–18.2)].

Timing of PMCD and Neonatal Survival

Mean times to PMCD were 14±11min (median=10, range=1–47) and 22 ± 13 min (median = 20, range = 4–60) in neonatal survivors and non-survivors respectively (p=0.016)

In cases with PMCD which reported outcome, the overall neonatal survival rate was 63.6% (42/66).

“The 4-min time frame advocated for PMCD usually remains unmet yet neonatal survival is still likely if delivery occurs within 10 or even 15 min of arrest”

Both maternal & neonatal mortality were higher with prehospital arrest location.

Summary

The study may be limited by recall bias, under-reporting and publication bias, but provides a more comprehensive evidence base on which to base resuscitation recommendations. The authors provide a useful warning against becoming fixated with the recommended four minute window, which may lead teams to fail to attempt a potentially life-saving intervention:

“Fixation on specific time frames for PMCD may not be ideal. It may be more important to focus on event recognition and good overall performance…. It may be wise to advocate a short time frame for performance of PMCD in order to achieve better outcomes; however, blanket endorsement of an unrealistic time frame may well create a defeatist attitude when that time frame cannot be met.”

Maternal cardiac arrest and perimortem caesarean delivery: Evidence or expert-based?
Resuscitation. 2012 Oct;83(10):1191-200
Click for abstract

London Calling – part 3

Notes from Day 4 of the London Trauma Conference

The highlight for me was Mr Jonny Morrison speaking on Resuscitative Emergency Balloon Occlusion of the Aorta (REBOA). He is a British military surgeon currently out in Texas studying balloon occlusion of the aorta on pigs. Looking at trauma deaths, the next unexpected survivors will come from the uncontrollable haemorrhage group (truncal and junctional zones). This is by no means a new technique – described in the 1950’s during the Korean War – but like the early Star Wars chapters, needed to wait for technology to advance to make it feasible. It has the effect of cross clamping the aorta which provides afterload support, increases cerebral and coronary perfusion and provides proximal inflow control – without the mess of a resuscitative thoracotomy and greater access.

The placement of the balloon is determined by the location of the injury (see photo) and falls into two zones. Zone 1 is the thoracic aorta and is used for truncal haemorrhage control, avoid Zone 2 where the celiac axis etc originates and Zone 3 is infrarenal, used for junctional bleeding and pelvic haemorrhage.

His studies have determined that for Zone 3 amenable bleeds balloon occlusion up to 60min is the optimal time. Any longer and the debt of the metabolic load is paid by increased inotropic support requirements. He also compared REBOA to the current standard treatment for junctional injuries, Celox™ gauze. If coagulation is normal then both treatments perform similarly, the benefit is seen in coagulopathic patients where REBOA outperforms the gauze.

Has REBOA been used on humans? Yes a case series of 13 – the technique improved the BP allowing time to get to definitive surgery (blogged here 2.5 years ago!).

The Zone 1 studies are looking at continuous vs intermittent balloon occlusion. The jury is still out as to which is better. With the intermittent occlusion (20min on, 1min off) there are inevitably some losses when the balloon is deflated, conversely the metabolic debt generated by continuous occlusion is too great in some also leading to deaths.

What was very clear is that for this technique to have an impact it must be delivered proactively and pre-hospital. The challenges that need to be overcome are access to the femoral artery and blind accurate placement.

Prof Karim Brohi brought the conference to a close with a summary of what we have learned about coagulation in trauma this year. Here are three things;

• FFP is good but as 43% deaths due to trauma in the UK are secondary to bleeding and occur in the first 3hr we are failing our patients by administering the treatment on average at 2.5hrs.

• Fibrinogen levels are low in coagulopathic trauma patients; we should give cryoprecipitate early and aim for Fib ≥2.0

• And finally whilst TEG is recommended to guide treatment and can provide results within 5 min, there are some aspects of coagulation it does not detect i.e. fibrinolysis was only detected in 8% of coagulopathic trauma patients – when measured in the plasma it was then detectable in 80%.

These are the highlights of the 2012 London Trauma Conference. I hope this whistle stop tour through these days has been informative and though provoking. I can assure you telephone hacking was not used to bring you this information and to my knowledge is correct.

This is Lou Chan, roving reporter for Resus ME! signing off.

 

 

‘London raises her head, shakes off the debris of the night from her hair, and takes stock of the damage done. The sign of a great fighter in the ring is can he get up from a fall after being knocked down… London does this every morning.’

 

 

Transtracheal airways in kids. Well, pigs’ kids anyway

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
Click for abstract

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

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