Profound hypothermia and no ECMO?

July 11, 2014 by  
Filed under Acute Med, All Updates, ICU, Kids, Resus

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Patients in cardiac arrest due to severe hypothermia benefit from extracorporeal rewarming, and it is often recommended that they are treated at centres capable of providing cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO).

But what if they’re brought to a centre that doesn’t have those facilities?

If you work in such a centre do you have a plan, and are you familiar with what equipment you could use?

One option if you have an ICU is to provide extracorporeal warming using a haemofiltration machine used for renal replacement therapy(1). A double lumen haemofiltration catheter is inserted into a central vein and an ICU nurse can often do the rest, although some variables have to be set by the intensivist, often aided by a standard renal replacement therapy prescription chart. The machines are mobile and can be wheeled into the resus room (I have practiced this set up in resus). It might be worth discussing and practicing this option with your ICU.

Another extracorporeal option is to rig up a rapid infusion device such as a ‘Level 1′ to connect to arterial and venous catheters so that blood from the patient flows through and is warmed by the machine before being returned to the patient(2). Rapid rewarming has been achieved by this method but it requires some modification to the usual set up and so is much less likely to be a realistic option for most teams doing this on very rare occasions.

Less technical options are the traditionally taught warm saline lavage of body cavities such as the thorax and the peritoneal cavity. These can be achieved with readily available catheters and of course should be combined with ventilation with warmed gas and administration of warm intravenous fluid.

Thoracic lavage can be achieved with open thoracotomy or tube thoracostomy. One or two chest tubes can be placed on each side. One technique was described as:


Two 36 French chest tubes were placed in each hemithorax. One tube was placed in the fourth intercostal space in the mid-clavicular line. Another tube was placed into the sixth intercostal space in the mid-axillary line. Sterile saline at 39.0◦C was infused by gravity into each superior chest tube and allowed to drain passively through each inferior tube.(3)

Rapid rewarming at a rate of 6.8◦C per hour was achieved in an arrested hypothermic man using peritoneal lavage. It was done in the operating room with peritoneal lavage (saline 40◦C) with a rapid infusion system (Level 1) through two laparoscopic access sites. It was combined with external forced air rewarming and warm intravenous infusions(4).

Finally some devices manufactured for inducing hypothermia in post-cardiac arrest patients can also be used to rewarm patients, which might be endovascular devices, such as the Cool Line® catheter(5), or external, such as the Arctic Sun® Temperature Management System(6). It’s definitely worth finding out what your critical care services have as far as this equipment goes.

In summary, although the ‘exam answer’ for cardiac arrest due to profound hypothermia is often ECMO/cardiopulmonary bypass, in most centres that’s not an option. It’s helpful to remind ourselves that (1) other extracorporeal rewarming options exist and (2) non-extracorporeal techniques can provide rapid rewarming.

 

1. Spooner K, Hassani A. Extracorporeal rewarming in a severely hypothermic patient using venovenous haemofiltration in the accident and emergency department. J Accid Emerg Med. 2000 Nov;17(6):422–4. Full text

2. Gentilello LM, Cobean RA, Offner PJ, Soderberg RW, Jurkovich GJ. Continuous arteriovenous rewarming: rapid reversal of hypothermia in critically ill patients. The Journal of Trauma: Injury, Infection, and Critical Care. 1992 Mar;32(3):316–25 PubMed

3. Plaisier BR. Thoracic lavage in accidental hypothermia with cardiac arrest — report of a case and review of the literature. Resuscitation. 2005 Jul;66(1):99–104. PubMed

4. Gruber E, Beikircher W, Pizzinini R, Marsoner H, Pörnbacher M, Brugger H, et al. Non-extracorporeal rewarming at a rate of 6.8°C per hour in a deeply hypothermic arrested patient. Resuscitation. 2014 Aug;85(8):e119–20. PubMed

5. Kiridume K, Hifumi T, Kawakita K, Okazaki T, Hamaya H, Shinohara N, et al. Clinical experience with an active intravascular rewarming technique for near-severe hypothermia associated with traumatic injury. Journal of Intensive Care. BioMed Central Ltd; 2014;2(1):11. link to abstract

6. Cocchi MN, Giberson B, Donnino MW. Rapid rewarming of hypothermic patient using arctic sun device. Journal of Intensive Care Medicine. 2012 Mar;27(2):128–30. PubMed

The ‘Magic Eye®’ method of rhythm assessment

February 9, 2014 by  
Filed under Acute Med, All Updates, EMS, ICU, Resus

Are you someone who tries to determine whether an ECG trace is ‘irregularly irregular’ by drawing little dots on a piece of paper level with the R waves to see if they are evenly spaced? I’d done that for years until I read this fantastic suggestion, which I’ve been following for over a year now.

In the 1990s there was a popular series of posters and books called ‘Magic Eye‘. These contained a ‘random dot autostereogram‘ which appeared as a mish-mash of coloured dots, but when you stared at it for a while the illusion of a 3D image would emerge. They looked a bit like this (although this one won’t work at such reduced resolution):

Image Credit: Wikimedia Commons

Image Credit: Wikimedia Commons

Dr Broughton and colleagues from Cambridge, UK, discovered that this technique, which involves forcing a divergent gaze to get repeating patterns to appear to overlap, can be applied to an ECG trace.

Stereoviewing an ECG trace causes successive QRS complexes to visually overlap and produce a new image. As Broughton and colleagues point out:

When achieved, this will lead to one of three outcomes. Entirely regular rhythms will ‘click’ into place as a new image at fixed depth. Rhythms with only mild irregularity may be stereoviewable, and if so, will appear to show successive QRS complexes at subtly varying depths. Rhythms with marked irregularity will not be stereoviewable, instead (in our experience) merely giving the viewer sore eyes after several failed viewing attempts.”

The authors assert that this can be applied to continuous ECG monitors, although unless you are really good at stereoviewing while moving your head/eyes horizontally, you should really freeze the trace on the screen first.

The ‘Magic Eye®’ method of rhythm assessment
Anaesthesia. 2012 Oct;67(10):1170-1

Thenar eminence based medicine

June 3, 2013 by  
Filed under All Updates, EMS, ICU, Kids, Resus, Trauma

thumbs-upA recent study showed superior effectiveness of one bag-mask ventilation style over another in novice providers. The technique recommended is the thenar eminence grip, in which downward pressure is applied with the thenar eminences while the four fingers of each hand pull the jaw upwards toward the mask.

Interestingly, in their crossover study in which the thenar emininence (TE) technique was compared with the traditionally taught ‘CE’ technique, they demonstrated a ‘sequence effect’. If subjects did TE first, they maintained good tidal volumes when doing CE. However if they did CE first, they achieved poor tidal volumes which were markedly improved when switching to TE.

The authors suggest: “A possible explanation for this sequence effect is that the TE grip is superior. When one used the TE grip first, he or she was more likely to learn how a good tidal volume “feels” and then more likely to apply good technique with the EC grip.“.

Some of us have been practicing and teaching this technique for a while. None have put it better than the brilliant Reuben Strayer of EM Updates in this excellent short video:


Efficacy of facemask ventilation techniques in novice providers
J Clin Anesth. 2013 May;25(3):193-7


STUDY OBJECTIVE: To determine which of two facemask grip techniques for two-person facemask ventilation was more effective in novice clinicians, the traditional E-C clamp (EC) grip or a thenar eminence (TE) technique.

DESIGN: Prospective, randomized, crossover comparison study.

SETTING: Operating room of a university hospital.

SUBJECTS: 60 novice clinicians (medical and paramedic students).

MEASUREMENTS: Subjects were assigned to perform, in a random order, each of the two mask-grip techniques on consenting ASA physical status 1, 2, and 3 patients undergoing elective general anesthesia while the ventilator delivered a fixed 500 mL tidal volume (VT). In a crossover manner, subjects performed each facemask ventilation technique (EC and TE) for one minute (12 breaths/min). The primary outcome was the mean expired VT compared between techniques. As a secondary outcome, we examined mean peak inspiratory pressure (PIP).

MAIN RESULTS: The TE grip provided greater expired VT (379 mL vs 269 mL), with a mean difference of 110 mL (P < 0.0001; 95% CI: 65, 157). Using the EC grip first had an average VT improvement of 200 mL after crossover to the TE grip (95% CI: 134, 267). When the TE grip was used first, mean VTs were greater than for EC by 24 mL (95% CI: -25, 74). When considering only the first 12 breaths delivered (prior to crossover), the TE grip resulted in mean VTs of 339 mL vs 221 mL for the EC grip (P = 0.0128; 95% CI: 26, 209). There was no significant difference in PIP values using the two grips: the TE mean (SD) was 14.2 (7.0) cm H2O, and the EC mean (SD) was 13.5 (9.0) cm H2O (P = 0.49).

CONCLUSIONS: The TE facemask ventilation grip results in improved ventilation over the EC grip in the hands of novice providers.

Lateral chest thrusts for choking

March 29, 2013 by  
Filed under Acute Med, All Updates, EMS, Guidelines, Kids, Resus, Trauma

An interesting animal study examined the techniques recommended in basic choking management algorithms for foreign body airway obstruction (chest and abdominal thrusts). In terms of the pressures generated, lateral chest thrusts were the most effective, although they are not recommended in current guidelines.

The technique described (on intubated pigs) was:


The animals were placed on the floor and on their side. The lower (dependent) side of the chest was braced by the ground and thrust was applied to the upper part of the upper side by two hands side by side with the higher one just below the axilla.

Interestingly – and I didn’t know this (although perhaps should have!) – the Australian Resuscitation Council (ARC) recommended lateral chest thrusts instead of abdominal thrusts for over 20 years.

While we should always exercise extreme caution in extrapolating animal studies to humans, this makes me want to consider lateral thrusts in the first aid (ie. no equipment) situation if other measures are failing.

Lateral versus anterior thoracic thrusts in the generation of airway pressure in anaesthetised pigs
Resuscitation. 2013 Apr;84(4):515-9


Objective Anterior chest thrusts (with the subject sitting or standing and thrusts applied to the lower sternum) are recommended by the Australian Resuscitation Council as part of the sequence for clearing upper airway obstruction by a foreign body. Lateral chest thrusts (with the victim lying on their side) are no longer recommended due to a lack of evidence. We compared anterior, lateral chest and abdominal thrusts in the generation of airway pressures using a suitable animal model.

Methods This was a repeated-measures, cross-over, clinical trial of eight anaesthetised, intubated, adult pigs. For each animal, ten trials of each technique were undertaken with the upper airway obstructed. A chest/abdominal pressure transducer, a pneumotachograph and an intra-oesophageal balloon catheter recorded chest/abdominal thrust, expiratory air flows, airway and intrapleural pressures, respectively.

Results The mean (SD) thrust pressures generated for the anterior, lateral and abdominal techniques were 120.9 (11.0), 135.2 (20.0), and 142.4 (27.3) cmH2O, respectively (p < 0.0001). The mean (SD) peak expiratory airway pressures were 6.5 (3.0), 18.0 (5.5) and 13.8 (6.7) cmH2O, respectively (p < 0.0001). The mean (SD) peak expiratory intrapleural pressures were 5.4 (2.7), 13.5 (6.2) and 10.3 (8.5) cmH2O, respectively (p < 0.0001). At autopsy, no rib, intra-abdominal or intra-thoracic injury was observed.

Conclusion Lateral chest and abdominal thrust techniques generated significantly greater airway and pleural pressures than the anterior thrust technique. We recommend further research to provide additional evidence that may inform management guidelines for clearing foreign body upper airway obstruction.

London Calling – part 2

December 9, 2012 by  
Filed under All Updates, EMS, ICU, Resus, Trauma

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

Reassurance: difficult laryngoscopy in children remains rare

December 2, 2012 by  
Filed under All Updates, EMS, ICU, Kids, Resus

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


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.

Externally rotate leg for femoral vein access

November 29, 2012 by  
Filed under Acute Med, All Updates, EMS, ICU, Kids, Resus, Ultrasound

Want to access the femoral vein? Externally rotate the leg at the hip and things might be a bit easier. This study was done in adult patients, with the knee straight and no abduction applied. External rotation is also helpful in kids, with abduction up to sixty degrees.


Objective: To determine if external rotation of the leg increases the size and accessibility of the femoral vein compared with a neutral position.

Methods: One hundred patients presenting to a tertiary teaching hospital were prospectively recruited. The right common femoral vein of each subject was scanned with a linear probe (5–10 MHz) inferior to the inguinal ligament, with the leg in a neutral position and then in the externally rotated position. The transverse diameter of the femoral vein, the accessible diameter of the vein (lying medial to the femoral artery) and the depth of the vein were measured.

Results: The mean diameter of the femoral vein in the externally rotated leg was greater than with the leg in the neutral position (15.4 mm vs 13.8 mm); the mean difference was 1.6 mm (95% CI 1.3–1.9). The mean accessible diameter of the femoral vein was larger with the leg externally rotated (13.8 mm vs 11.7 mm, mean difference 2.1 mm, 95% CI 1.8–2.5). The depth from the skin to the femoral vein was less with the leg in external rotation (20.9 mm vs 22.6 mm, mean difference 1.7 mm, 95% CI 1.2–2.2). The mean diameter and depth were greater in patients with overweight or obese body mass index (BMI) measurements in both leg positions. The increase in femoral vein diameter and accessibility with external rotation was observed in all BMI groups.

Conclusion: The total and accessible femoral vein diameter is increased and the surface depth of the vein is decreased by placing the leg in external rotation compared with the neutral position.

Simple external rotation of the leg increases the size and accessibility of the femoral vein
Emerg Med Australas. 2012 Aug;24(4):408-13

Finally I understand ultrasound physics

October 20, 2012 by  
Filed under All Updates, ICU, Resus, Ultrasound

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Ever waste time trying to shake some ultrasound gel out the bottle, like a resistant blob of ketchup?
Sydney emergency medicine registrar Dr Steve Skinner demonstrates how to solve this. With physics.

This really does work, and has saved me a lot of time already. I now do a somewhat less ballistic version than the one demonstrated, so that patients don’t think I’m mad.



This video is for entertainment purposes only. We accept no responsibility for injuries sustained as a result of unaccustomed shoulder activity or inadvertently launched plastic projectiles.

Still no oil painting

October 13, 2012 by  
Filed under Trauma, Ultrasound

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During a Krav Maga self defence drill a middle aged martial arts enthusiast cleverly blocked a full contact punch with his nose. Following a suggestion to pause training to control the bleeding, he noticed some lateral nasal displacement which was easily manually reduced with an audible click. He was able to resume training with a piece of toilet paper stuffed up the bleeding nostril, and no ill effects were noticed on subsequent training nights that week.

The day after injury he demonstrated a characteristic bruising pattern:

As he was working an aeromedical retrieval shift, he was able to use the Retrieval Service Sonosite M-Turbo ultrasound machine to identify the cortical disruption from his nasal bone fracture.

Ultrasound compares favourably with both plain radiography(1) and computed tomography(2) in the diagnosis of nasal bone fractures.

Personal access to sonography and full board certification in emergency medicine help to decrease health care costs and emergency department load when individuals sustain fractures that do not require operative management(3).

1. Comparison of ultrasonography and conventional radiography in the diagnosis of nasal fractures.
Arch Otolaryngol Head Neck Surg. 2005 May;131(5):434-9

2. Comparison of high-resolution ultrasonography and computed tomography in the diagnosis of nasal fractures.
J Ultrasound Med. 2009 Jun;28(6):717-23

3. Only when I laugh
When the same bloke broke his rib

Facilitated pericardial drainage

October 2, 2012 by  
Filed under Acute Med, All Updates, Resus

Drs Wyatt and Haugh describe a modified resuscitative thoracotomy technique which provided surgically facilitated pericardial drainage. A patient with a ruptured pseudoaneurysm of the right ventricular outflow tract presented in shock and arrested in the ED. She had had a prior history of idiopathic ventricular tachycardia and had undergone cardiac ablation of the posteroseptal wall of the right ventricular outflow tract. Sonographically identified tamponade was treated with pericardiocentesis which failed due to clotted blood, so a left lateral thoracotomy was performed by the emergency physician. Rather than fully expose the heart for repair in the ED, they elected to just make a 2cm incision in the pericardium which allowed drainage of blood and restoration of circulation. This was combined with blood product transfusion to buy time for the arrival of a cardiothoracic surgeon and transfer to the operating room.

Useful learning points from this paper are:

  • Ablation procedures are becoming more common
  • Serious complications such as atrioesophageal fistula, pseudoaneurysm, pericardial effusion, and cardiac tamponade occur approximately 3% of the time
  • When tamponade is suspected or confirmed ask patient about recent cardiac procedures such as catheterisations, surgery, and ablation procedures
  • Radiofrequency ablation procedures are often performed on the right side of the heart in areas that may be relatively inaccessible from a left-sided lateral thoracotomy approach.

Modified Emergency Department Thoracotomy for Postablation Cardiac Tamponade
Ann Emerg Med. 2012 Apr;59(4):265-7


Cardiac dysrhythmias are a common problem in the United States. Radiofrequency ablation is being used more frequently as a treatment for these diagnoses. Although rare, serious complications such as cardiac tamponade have been reported as a result of ablation procedures. Traditionally, emergency department (ED) thoracotomy has been reserved for cases of traumatic arrest only. We report a case of a successful modified ED thoracotomy in a patient with postablation cardiac tamponade and subsequent obstructive shock who failed intravenous fluid resuscitation, pressor administration, and multiple attempts at pericardiocentesis. In this case, a modified approach was used to incise the pericardium. Although this was associated with large blood loss, we believed that using the traditional method of completely removing the pericardium would have resulted in uncontrolled hemorrhage. Instead, our method led to successful resuscitation of the patient until definitive care was available. A smaller pericardial incision than is traditionally used during ED thoracotomy deserves further consideration and research to determine whether and when it may be most useful as a temporizing treatment of cardiac tamponade when other methods have failed.

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