Greater Sydney Area HEMS

Take caution if you ever get tasked to a pre-hospital trauma at David Bowie’s house. His reduced level of consciousness and blown pupil might just be due to a copious amount of mind-bending drugs and the accident as a school-boy which left him with a unilateral pupillary defect.¹  In my mind he still gets a tube and the paramedic can do it, but he only gets “one shot“?!?²

Anisocoria is characterised by unequal pupil sizes, but not necessarily as a consequence of mydriasis; a dilated pupil. There are also many pre-hospital causes of a unilateral miosis; a constricted pupil.³

A “blown” pupil is the colloquial term used by medics to refer to a fixed unilateral mydriasis.⁴

Case: Our HEMS team was called to a rural trauma involving two motocross riders. The more seriously injured victim had obvious right-sided facial and thoracic injuries, had a blown right pupil and a GCS 3 (with no external signs of head trauma). He received an RSI and bilateral thoracostomies. His pupillary signs did not improve with a bolus of hypertonic saline bolus and hyperventilation in transit.

The head CT performed at the trauma centre revealed no gross intracranial pathology requiring neurosurgical intervention, but did show a right-sided retrobulbar haematoma, which was thought to account for his unilateral fixed dilated pupil.

Challenge: To understand the pathophysiology of pupillary signs and when a “blown” pupil might not be a consequence of uncal herniation.

Pathophysiology: Pupillary size is governed by the balance of actions of two opposing muscle groups of the iris: the dilator and sphincter pupillae controlled by the autonomic nervous system.

Constriction of the size of the pupil is mediated via parasympathetic (cholinergic) nerve fibers that travel superficially with the third cranial nerve. The pupil will respond to circulating catecholamines but dilation is controlled by sympathetic fibres originating from the superior cervical ganglia.^5,6

Each eye’s sensory pathway is linked with its counterpart by partial crossover of fibers in the Edinger-Westphal nuclei which accounts for the consensual response to light.⁷

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Tourniquets: villain or hero?

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Case: The team are called to a freeway scene where a motorcyclist has hit a tree. The victim is obviously shocked and has a reduced GCS. His left leg has been severed just below the knee and the stump is bleeding profusely. The amputated portion of his limb is 10 metres away in the grass verge. The HEMS team apply a MAT* to the left thigh and then intubate and ventilate the victim. They perform bilateral thoracostomies prior to transfer by helicopter to a trauma centre. He is taken straight to theatre where the orthopods perform an above knee amputation. Before the HEMS team leave, the Crewie is asked to pick up the severed portion of the left leg. When they ask what they should do with it, the paramedic suggests he put it in the ‘boot’?!!?

Challenge: When, why and how to correctly apply a pre-hospital tourniquet.

Tourniquets fall from grace: (Not the rock band!?!)

• Majority of external haemorrhage can be controlled by direct pressure.
• Previously tourniquets have been used inappropriately when not clinically indicated.
• Preventing arterial blood flow to a limb will result in ischaemia.
• Continuous application > 2hrs can result in permanent nerve injury, muscle injury, vascular injury and skin necrosis.

The general conclusion is that a tourniquet can be left in place for up to 2hrs with little risk of permanent ischaemic injury. However the majority of the literature looks at pneumatic tourniquets in elective theatre cases with normovolaemic patients.²

Lakstein found a 5% complication rate in 110 applications of a pre-hospital tourniquet and identified a mean ischaemic time of 78 minutes with no complications.³ None of the complications resulted in limb loss.

Learning Points: Tourniquets are an effective means of arresting life-threatening external haemorrhage from limb injury.⁴ The new military trauma paradigm teaches; control of catastrophic haemorrhage takes priority over airway and breathing assessment.⁵

Indications:

• Extreme life-threatening limb haemorrhage or limb amputation/ mangled limb.
• Life-threatening limb haemorrhage not controlled by simple methods.
• To allow immediate management of airway or breathing problems. (then reassess need in circulatory assessment).
• Point of significant haemorrhage not peripherally accessible, e.g. entrapment.
• Major incident or multiple casualties with extremity haemorrhage and lack of resources.
• When benefits of preventing death from hypovolaemic shock by cessation of ongoing external haemorrhage is greater than the risk of limb damage or loss from ischaemia caused by tourniquet use.⁶

Pit-falls:

• Re-perfusion injury: inflammation induced injury of previously hypo-perfused areas and organ damage from systemically released mediators.
• Increased bleeding from distal tissues when venous outflow is obstructed but arterial blood flow is inadequately occluded.
• After resuscitation of the hypotensive patient, a higher systolic pressure may re-start bleeding.
• Periodical loosening, in an attempt to reduce limb ischaemia, has lead to incremental exsangination.
• A properly applied tourniquet is painful and this has led to inadequate tightening or premature removal.

Application:

• Familiarise yourself with your own kit. In our case, the *Mechanical Advantage Tourniquet by Pyng Medical.
• The tourniquet must completely and consistently occlude arterial blood flow.
• The pressure required to occlude blood flow in a limb increases exponentially with the circumference of the limb.⁷
• Placement of the tourniquet as distal as possible, but at least 5 cm proximal to injury.
• Spare joints as much as possible, ideally onto exposed skin.
• Effectiveness determined by cessation of external haemorrhage, not by presence or absence of a distal pulse.
• Slight oozing may still occur especially if there is medullary bone blood flow.
• If ineffective, tighten or reposition.
• Still ineffective, consider a second tourniquet placed just proximal to the first.
• Application time should be recorded and device should be removed in theatre.

Consider exposing the tourniqueted limb to the environment to allow cooling or artificially trying to achieve local hypothermia.⁸

Summary: Use a commercial tourniquet in specific pre-hospital situations.⁹ Make sure the intervention has been effective and document the application time. Get the victim to a trauma theatre as soon as possible.

References:

1. Mabry, R. L. 2006. “Tourniquet use on the battlefield.” Military medicine 171(5): 352-356.

2. Wakai, A., Winter, D. C., Street, J. T., et al. 2001 Pneumatic tourniquets in extremity surgery. J Am Acad Orthop Surg;9:345–51.

3. Lakstein, D., Blumenfield, A., Sokolov, T., et al. 2003. Tourniquets for hemorrhage control on the battlefield: 4 year accumulated experience. J Trauma;54(5 Suppl):S221–5.

4. Champion, H. R., Bellamy, R. F., Roberts, P., et al. 2003. A profile of combat injury. J Trauma;54:S13–19.

5. Hodgetts, T. J., Mahoney, P. F., Russell, M. Q., et al. 2006. ABC to ,C.ABC: redefining the military trauma paradigm. EMJ;23:745–6.

6. Lee, C., Porter, K. M., Hodgetts, T. J., 2007. Tourniquet use in the civilian prehospital setting Med. J. Emerg;24;584-587.

7. Walters, T. J., Mabry, R. L., 2005. Issues related to use of tourniquets on the battlefield. Mil Med;170:770–5.

8. Irving, G.A., Noakes, T.D. 1985. The protective role of local hypothermia in tourniquet-induced ischaemia of muscle. J Bone Jt Surg;67:297–301.

9. Navein, J., Coupland, R., Dunn, R. 2003. The tourniquet controversy. J Trauma: 54(5 Suppl):S219–20.

“Sentio aliquos togatos contra me conspirare”

In Greek mythology, the Sirens were dangerous creatures, portrayed as femme fatales who drowned sailors with their enchanting music and voices.¹

Drowning is a process resulting in primary respiratory impairment from submersion /immersion in a liquid medium.²

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A liquid/air interface at the entrance to the airway prevents the victim from breathing air. The victim may live or die after this process.²

Case: A 15 yr old was playing with his brother outside by a dam. Their mother was unaware of the childrens’ location for 10 minutes. The alarm was raised by the brother. The teenager was found by his mother face down in the water, blue and apnoiec. She gave rescue breaths, and the boy started to breath spontaneously.

On arrival of the HEMS team, the boy is cold and smells of vomitus. His saturations are in the 80s and he is agitated with a GCS 5/15. His pupils are large and minimally reactive to light.

He receives IO access and an RSI for airway and neurological protection. During his transfer to a trauma centre, his observations steadily improved. His made a rapid recovery in the ICU and he was discharged neurologically intact.

Challenge: How do we optimise the drowning victim’s chances of a full neurological recovery?

Pathophysiology: From the point at which the airway lies below the surface of the liquid, the victim voluntarily holds his or her breath. Breathholding is usually followed by an involuntary period of laryngospasm secondary to the presence of liquid in the oropharynx or larynx.³ The victim then becomes hypercarbic, hypoxemic, and acidotic.

During this time the victim will frequently swallow large quantities of water. As the victim’s arterial oxygen tension drops further, laryngospasm abates, and the victim actively breathes liquid. Surfactant washout, pulmonary hypertension, and shunting also contribute to development of hypoxaemia.⁴

Modern day sirens or the antidote?

Learning Points: The most important and detrimental consequence of drowning is hypoxia. Oxygenation, ventilation, and perfusion should be restored as rapidly as possible. Ideally this should be initiated by the first responder.⁴

The reported incidence of cervical spine injury in drowning victims is low (0.009%).⁵ Unnecessary cervical spine immobilization could impede initiation of adequate oxygenation. Routine stabilization of the cervical spine in the absence of circumstances that suggest a spinal injury is not recommended in the AHA guidelines.⁶ 

In a 10-year study in Australia, 66% of victims who received rescue breathing and 86% of those who required compressions and ventilations, vomited.⁷ So have the suction at the ready and be prepared to roll the patient if necessary.

V/Q mismatch, reduced compliance and acidosis lead to reduced O2 delivery and anoxic brain injury. This is the leading cause of death or morbidity in drowning victims.

Many of the other sequelae are actually related to the hypothermia that often accompanies drowning. Water that is <10°C has pronounced cardiovascular effects, including increased blood pressure and ectopic tachyarrhythmias. Please see a future blog for more on this topic….

Summary: Like our trusted HEMS team in the above scenario, doing the simple things well, can lead to a favourable outcome.

References:

1. Prescott, J. 1942. “Homer’s Odyssey and Joyce’s Ulysses.” Modern Language Quarterly 3(3): 427-444.

2. Idris, A., R. Berg, et al. 2003. “Recommended guidelines for uniform reporting of data from drowning.” Circulation 108(20): 2565-2574.

3. Miller, R. D., 2000. Ed. Anesthesia. 5th ed. Philadelphia, Pa: Churchill Livingstone: 1416–1417.

4. Circulation. November 2, 2010, Volume 122, Issue 18 suppl 3.

5. Weinstein, M.D., Krieger, B. P., 1996. Near-drowning: epidemiology, pathophysiology, and initial treatment. J Emerg Med;14:461–467.

6. Watson, R. S., Cummings, P., Quan, L., Bratton, S., Weiss, N. S., 2001. Cervical spine injuries among submersion victims. J Trauma;51:658–662.

7. Manolios, N., Mackie, I. 1988. Drowning and near-drowning on Australian beaches patrolled by life-savers: a 10-year study, 1973–1983. Med J Aust;148:165–167, 170–171.

“Periculum in mora”

Clam shell thoracotomy – Indications and outcomes

Case: A multiple gun shot wound victim was found at the roadside barely conscious. He was intubated, ventilated and given bilateral thoracostomies by our HEMS crew. He went into cardiac arrest and so the team decided to perform an open thoracotomy¹. His pericardium was full of clot and when opened revealed a linear tear in his right ventricle. During bimanual cardiac compressions his heart felt empty. The extent of his injuries, including the one described above, were judged to be an ELE (Extinction Level Event).

Challenge: What are the indications and reported outcomes for prehospital thoracotomy?

Learning Points: Here’s an excerpt from the Traumatic Cardiac Arrest HOP:

4.6.3. Penetrating Trauma

4.6.3.1 Thoracic or upper abdominal penetrating injury resulting in cardiac arrest should initially be managed as in 4.1.1 and 4.2.1 (see below). If there are signs of life withint a 10 min window prior to team arrival and there is no response to intubation / bilateral thoracostomy, a clamshell thoracotomy should be made with the specific purpose of relieving cardiac tamponade, controlling a cardiac wound(s) and providing internal cardiac massage. A detailed description of this technique is beyond the scope of this HOP but is clearly explained elsewhere¹ .

4.1.1 All cardiac arrest patients should be intubated without anaesthetic drugs.

4.2.1 Unless the possibility of tension pneumothorax can be reliably excluded, bilateral open thoracostomies should be made². Needle thoracocentesis may be performed initially for reasons of access or expediency but these should not be considered to provide definitive pleural drainage.

Anterior bilateral thoracotomy (Clam Shell): Provides excellent exposure of the heart and mediastinum. The idea is that a non-cardiothoracic surgeon should be able to access the pericardium with 2-3 mins. 

Indication: Penetrating chest or epigastric trauma associated with cardiac arrest.

Contraindications: Cardiac arrest for greater than 10mins (or if there is still a cardiac output?!). Evidence from one case series suggested a poor neurological outcome for those patients who were in cardiac arrest for anymore than 10 mins³.

It is important to have realistic expectations. This procedure best tackles a single pathology – cardiac tamponade with a controllable wound in the heart. If the underlying injury is any more complex, a good outcome is unlikely. A 25 year review of ED thoracotomies conducted in 2000 highlighted survival rates based on mechanism of injury. In descending order: 19.4% for isolated cardiac wounds, 16.8% for stab wounds, 4.3% for gunshot wounds and 1% for blunt trauma⁴.

Summary: Clam shell thoracotomy is a useful tool in the desperate attempt to resuscitate penetrating trauma victims who are in extremis. If applied selectively, this procedure can be lifesaving.

References:

1. Wise D, Davies G, Coats T, Lockey D, Hyde J, Good A. Emergency thoracotomy: “how to do it” Emergency Medicine Journal 2005;22:22-24.

2. Massarutti D, Trillò G, Berlot G, Tomasini A, Bacer B, D’Orlando L, Viviani M, Rinaldi A, Babuin A, Burato L, Carchietti E. Simple thoracostomy in prehospital trauma management is safe and effective: a 2-year experience by helicopter emergency medical crews. Eur J Emerg Med. 2006 Oct;13(5):276- 80.

3. Davies GE, Lockey DJ. Thirteen Survivors of Prehospital Thoracotomy for Penetrating Trauma: A Prehospital Physician-Performed Resuscitation Procedure That Can Yield Good Results. J. Trauma. 2011 May;70(5):E75-8.

4. Rhee PM, Acosta J, Bridgeman A, Wang D, Jordan M, Rich N. Survival after emergency department thoracotomy: review of published data from the past 25 years. J Am Coll Surg. 2000 Mar;190(3):288-98.

“Amat Victoria Curam”

Suxamethonium and neurological disorders

Analgesia for the head injured patient