26: Emergency Medical Systems

Section 26 Emergency Medical Systems



Edited by George Jelinek




26.1 Pre-hospital emergency medicine







Dispatch


Many countries now have a single telephone number for immediate access to the ambulance service in cases of emergency, such as 911 in North America, 999 in the UK and 000 in Australasia. However, the accurate dispatch of the correct ambulance skill set in the optimal time frame is complex. It is inappropriate to dispatch all ambulances on a ‘code 1’ (lights and sirens) response, since this entails some level of risk to the ambulance officers and other road users. On the other hand, it may be difficult to accurately identify life-threatening illnesses or injuries using information gained from telephone communication alone, especially from bystanders. Also, it is inappropriate to dispatch ambulance officers with advanced life-support training to routine cases where these skills are not required.


In order to have consistent, accurate dispatch of the appropriate skill set in the optimal time frame, many ambulance services are now using computer-aided dispatch programs. These computer programs have structured questions for use by call-takers with some limited medical training. Pivotal to accurate dispatch is identification of the chief complaint, followed by subsequent structured questions to determine the severity of the illness. The answers to these questions allow the computerized system to recommend the optimal skill set and speed of response. This computer algorithm is medically determined according to local protocols and practices and provides consistency of dispatch.


Most ambulance services generally have at least four dispatch codes. A code 1 (or local equivalent terminology) is used for conditions that are considered immediately life-threatening. For these, emergency warning devices (lights and sirens) are routinely used. The possibility of life-saving therapy arriving as soon as possible is judged as outweighing the potential hazard of a rapid response. In a code 2 (or equivalent) response, the condition is regarded as being urgent and emergency warning devices are used only when traffic is heavy. In a code 3 response, an attendance by ambulance within an hour is deemed medically appropriate. Finally, non-emergency or ‘booked’ calls are transports arranged at a designated time negotiated by the caller and the ambulance service.


Despite continuous developments in computer algorithms, accurate telephone identification of life-threatening conditions may be difficult. For example, identification of patients who are deceased (beyond resuscitation),1 in cardiac arrest2 or suffering acute coronary syndrome3 has been shown to lack the very high sensitivity and specificity that might be expected.


The dispatch centre also has a role for telephone instructions on bystander cardiopulmonary resuscitation4 and first aid.




Trauma care


Pre-hospital trauma care may be considered as either basic trauma life support (clearing of the airway, administration of supplemental oxygen, control of external haemorrhage, spinal immobilization, splinting of fractures and the administration of inhaled analgesics) or advanced life support including intubation of the trachea, intravenous (i.v.) cannulation and fluid therapy, and the administration of i.v. analgesia.



Basic trauma life support


On arrival at the scene of the patient with suspected major trauma, ambulance officers are trained to perform an initial ‘DR-ABCDE’ evaluation, which is similar to the approach that has been developed for physicians, namely consideration of dangers, response, airway, breathing, circulation, disability and exposure. Of particular importance in the pre-hospital trauma setting are dangers to ambulance officers from passing traffic, electrical wires and fire from spillage of fuel.


The initial assessment of the airway and breathing includes the application of cervical immobilization in patients who have a mechanism of injury that suggests a risk of spinal column instability. Although decision instruments have been developed to identify patients in the ED who require radiographic imaging,5 the accuracy of these guidelines in the pre-hospital setting is uncertain. On the other hand, spinal immobilization of many patients with minimal risk of spinal cord injury is uncomfortable, mandates transport and possibly leads to unnecessary radiographic studies.6 Therefore, ambulance officers are generally instructed to immobilize the neck in all cases of suspected spinal-column injury based largely on mechanism of injury.


Accurate triage of major trauma patients is an important component of trauma care in cities with designated major trauma centres. Triage tools based on vital signs, injuries and modifying factors such as age, comorbidities and mechanism of injury are used.7 Paramedic judgement may also have a role, although some injuries such as occult intra-abdominal injuries are difficult to detect on clinical grounds.8



Advanced trauma life support


Advanced trauma life support (ATLS) by ambulance paramedics, particularly intubation of the trachea and i.v. cannulation for fluid therapy, is controversial. Although these interventions are routinely used after hospital admission, studies to date indicate that the provision of ATLS provided by paramedics does not improve outcomes.9,10 On the other hand, few studies conducted to date have been sufficiently rigorous to allow definitive conclusions, and many were conducted in cities with predominantly penetrating trauma rather than blunt trauma. Many ambulance services therefore continue to authorize advanced airway management and i.v. fluid resuscitation in selected trauma patients.



Intubation


Following severe head injury, many unconscious patients have decreased oxygenation and ventilation during pre-hospital care, and this secondary brain injury is associated with worse neurological outcome.11 In addition, a depressed gag or cough reflex may lead to aspiration of vomit and this may cause a severe pneumonitis, which may be fatal or result in a prolonged stay in an intensive-care unit. To prevent these complications of severe head injury, endotracheal intubation may be performed. This facilitates control of oxygen and carbon dioxide, provides airway protection and is recommended for patients with Glasgow Coma Score <9 following severe head injury.12 However, most patients with severe head injury maintain a gag or cough reflex, and successful intubation requires the use of drugs to facilitate laryngoscopy and placement of the endotracheal tube.


The usual approach involves rapid sequence intubation (RSI), which is the administration of both a sedative drug and a rapidly acting muscle relaxant such as suxamethonium. It is unclear from the literature as to whether RSI should be performed pre-hospital by ambulance paramedics or be performed in an ED by appropriately trained physicians.


There is some evidence that pre-hospital intubation in head injury is beneficial.13,14 In a study of 671 patients with severe head injury, intubation in the field using RSI was associated with a decrease in mortality rate from 56% to 36%.13 In another study of 799 patients with severe head injury, patients intubated using RSI in the field were compared with those not intubated.14 When adjusted for confounding variables, the RSI patients were more likely to survive (odds ratio, 0.63; 95% confidence interval, 0.41–0.97; P = 0.04) and have a good outcome (odds ratio, 1.7; 95% confidence interval, 1.2–2.6; P = 0.006) than those in the no-RSI group.


However, two studies have suggested that pre-hospital intubation may be associated with worse outcome in head trauma patients.15,16 In a review of registry data of patients admitted to an urban trauma centre with severe head injury, patients were stratified by pre-hospital methods of airway management (not intubated, intubated or unsuccessful intubation).15 This study showed that patients requiring pre-hospital intubation or in whom intubation was attempted had an increased mortality (81% and 77%, respectively) when compared with non-intubated patients (43%).


In a second study, RSI was introduced as a protocol for adult patients with severe head injury in San Diego, USA, and the effect on outcome was assessed compared with historical controls.16 Each study patient was hand-matched to three non-intubated historical controls from a trauma registry using the following parameters: age, sex, mechanism of injury, trauma centre and AIS score for each body system. The study enrolled 209 trial patients who were hand-matched to 627 controls. Both groups were similar with regard to all matching parameters, admission vital signs, frequency of specific head injury diagnoses and incidence of invasive procedures. Mortality was significantly increased in the RSI cohort versus controls for all patients (33.0% versus 24.2%, P < 0.05).


Given the limited evidence of benefit and potential for harm with intubation in head injury, it has been proposed that intubation not be introduced into paramedic practice until prospective randomized, controlled trials have been conducted.17



Intravenous fluid


Intravenous fluid resuscitation has been shown to worsen outcome in patients with penetrating trauma and hypotension.18 However, this finding has recently been questioned.19 In any case, most major trauma in Australasia and Europe is blunt rather than penetrating and few patients require urgent surgical control of haemorrhage. The issue of pre-hospital i.v. fluid for the treatment of hypotension therefore remains the subject of debate.


Supporters of pre-hospital i.v. fluid therapy suggest that this treatment is intuitively beneficial and that any delay of this therapy increases the adverse effects of prolonged hypotension, which may result in end-organ ischaemia, leading to multiorgan system failure and increased morbidity and mortality. In particular, hypotension after severe head injury is associated with an adverse outcome and should be promptly treated.20


Opponents of pre-hospital i.v. fluid therapy suggest that this therapy prior to surgical control in patients with uncontrolled bleeding increases blood loss due to increased blood pressure, dilution coagulopathy and hypothermia from large volumes of unwarmed fluid. Any additional blood loss would increase transfusion requirements and could be associated with increased morbidity and mortality. Also, ambulance paramedic training and skills maintenance in pre-hospital fluid therapy is costly and may not be justified without some evidence of patient benefit.


There is no evidence from clinical trials for benefit of the administration of i.v. fluid to bleeding patients in the pre-hospital setting. Studies to date suggest that pre-hospital i.v. fluid does not improve outcomes.8,9 Nevertheless, if i.v. fluid is given to patients with hypotension and severe head injury, crystalloid rather than colloid should be given.21




Cardiac care



Cardiac arrest


In 1967, external defibrillation was introduced into pre-hospital care and this led to the development of mobile coronary care units in many countries for the delivery of advanced cardiac care for the patient with suspected myocardial ischaemia. This approach was subsequently extended to rapid response for defibrillation of patients in cardiac arrest. Protocols for the management of pre-hospital cardiac arrest are based on the concept of the ‘chain of survival’, which includes an immediate call to the ambulance service, the initiation of bystander CPR, early defibrillation and advanced cardiac life support (intubation and drug therapy).


The patient in cardiac arrest represents the most time-critical patient attended by ambulance services. For the patient with ventricular fibrillation, each minute increase from time of collapse to defibrillation is associated with an increase in mortality of approximately 10%. However, most ambulance services have urban response times that average 8–9 min. Since there may be 2 min between collapse and dispatch, and 1 min between arrival at the scene to delivery of the first defibrillation, total time from collapse to defibrillation would usually be approximately 12 min, therefore current survival rates for witnessed cardiac arrest due to defibrillation in urban areas are low24 and there are even fewer survivors in rural areas.25


The most effective strategy to improve outcomes would be to decrease ambulance response times. However, this would require very significant increases in ambulance resources and would be an expensive strategy in terms of cost per life saved. Alternatively, response times to cardiac arrest patients may be reduced with the use of co-response by first responders equipped with defibrillators. Such first responder programmes have been introduced in Melbourne, Australia,26 and Ontario, Canada,27 with promising results.


The role of advanced life support (intubation and i.v. drug therapy) during cardiac arrest remains controversial. When these skills were introduced into Ontario, Canada, there was an increase in the numbers of patients with return of spontaneous circulation (10.9% versus 14.6%, P < 0.001) but the rate of survival to hospital discharge did not significantly increase (5.0% versus 5.1%, P = 0.83).28




Cardiac arrhythmias


Some patients with an acute coronary syndrome develop a cardiac arrhythmia during ambulance care. Pulseless ventricular tachycardia is treated with immediate defibrillation, and amiodarone is recommended for ventricular tachycardia where a pulse is palpable.30 However, the pre-hospital drug treatment of supraventricular tachycardia is more controversial. Whilst the use of verapamil or adenosine appears to be equivalent in efficacy,31 many ambulance services require the patient to be transported for 12-lead electrocardiography and management of the tachyarrhythmia in an ED.



Pulmonary oedema


During myocardial ischaemia, the patient may develop pulmonary oedema and in these patients the use of oxygen and glyceryl trinitrates is regarded as useful.32 Despite common use in the ED, pre-hospital continuous positive airways pressure for acute pulmonary oedema has not been widely adopted, since the equipment is expensive, oxygen consumption is high and there is no proven benefit with pre-hospital administration of continuous positive airways pressure at this time.



Other medical emergencies







References



1 Harvey L, Woollard M. Outcome of patients identified as dead (beyond resuscitation) at the point of the emergency call. Emergency Medicine Journal. 2004;21:367-369.


2 Flynn J, Archer F, Morgans A. Sensitivity and specificity of the medical priority dispatch system in detecting cardiac arrest emergency calls in Melbourne. Prehospital and Disaster Medicine. 2006;21:72-76.


3 Deakin CD, Sherwood DM, Smith A, et al. Does telephone triage of emergency (999) calls using Advanced Medical Priority Dispatch (AMPDS) with Department of Health (DH) call prioritisation effectively identify patients with an acute coronary syndrome? An audit of 42,657 emergency calls to Hampshire Ambulance Service NHS Trust. Emergency Medicine Journal. 2006;23:232-235.


4 Vaillancourt C, Verma A, Trickett J, et al. Evaluating the effectiveness of dispatch-assisted cardiopulmonary resuscitation instructions. Academic Emergency Medicine. 2007;14:877-883.


5 Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization study (NEXUS) Group. New England Journal of Medicine. 2000;343:94-99.


6 Armstrong BP, Simpson HK, Crouch R, et al. Prehospital clearance of the cervical spine: does it need to be a pain in the neck? Emergency Medicine Journal. 2007;24:501-503.


7 Markovchick VJ, Moore EE. Optimal trauma outcome: trauma system design and the trauma team. Emergency Medicine Clinics of North America. 2007;25:643-654.


8 Mulholland SA, Gabbe BJ, Cameron P. Victorian State Trauma Outcomes Registry and Monitoring Group (VSTORM). Is paramedic judgement useful in prehospital trauma triage? Injury. 2005;36:1298-1305.


.


9 Isenberg DL, Bissell R. Does advanced life support provide benefits to patients? A literature review. Prehospital Disaster Medicine. 2005;20:265-270.


10 Liberman M, Mulder D, Lavoie A. Multicenter Canadian study of prehospital trauma care. Annals of Surgery. 2003;237:153-160.


11 Chi JH, Knudson MM, Vassar MJ, et al. Prehospital hypoxia affects outcome in patients with traumatic brain injury: a prospective multicenter study. Journal of Trauma. 2006;61:1134-1141.


12 www.braintrauma.org/prehospital. (accessed January 2008)


13 Winchell RJ, Hoyt DB. Endotracheal intubation in the field improves survival in patients with severe head injury. Archives of Surgery. 1997;132:592-597.


14 Bulger EM, Copass MK, Sabath DR. The use of neuromuscular blocking agents to facilitate prehospital intubation does not impair outcome after traumatic brain injury. Journal of Trauma. 2005;58:718-723.


15 Murray JA, Demetriades D, Berne TV, et al. Prehospital intubation in patients with severe head injury. Journal of Trauma. 2000;49:1065-1070.


16 Davis DP, Hoyt DB, Ochs M, et al. The effect of paramedic rapid sequence intubation on outcome in patients with severe traumatic brain injury. Journal of Trauma. 2003;54:444-453.


17 Bernard SA. Paramedic intubation of patients with severe head injury: a review of current Australian practice and recommendations for change. Emergency Medicine of Australasia. 2006;18:221-228.


18 Bickell W, Pepe P, Mattox K, et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. New England Journal of Medicine. 1994;331:1105-1108.


19 Yaghoubian A, Lewis RJ, Putnam B. Reanalysis of prehospital intravenous fluid administration in patients with penetrating truncal injury and field hypotension. American Surgicals. 2007;73:1027-1030.


20 Chesnut RM, Marshall LF, Klauber MR, et al. The role of secondary brain injury in determining outcome from severe head injury. Journal of Trauma. 1993;34:216-222.


21 SAFE Study Investigators. Saline or albumin for fluid resuscitation in patients with traumatic brain injury. New England Journal of Medicine. 2007;357:874-884.


22 Buntine P, Thom O, Babl F, et al. Prehospital analgesia in adults using inhaled methoxyflurane. Emergency Medicine Australasia. 2007;19:509-514.


23 Rickard C, O’Meara P, McGrail M, et al. A randomized controlled trial of intranasal fentanyl vs intravenous morphine for analgesia in the prehospital setting. American Journal of Emergency Medicine. 2007;25:911-917.


24 Fridman M, Barnes V, Whyman A, et al. A model of survival following pre-hospital cardiac arrest based on the Victorian Ambulance Cardiac Arrest Register. Resuscitation. 2007;75:311-322.


25 Jennings PA, Cameron P, Walker T, et al. Out-of-hospital cardiac arrest in Victoria: rural and urban outcomes. Medical Journal of Australia. 2006;185:135-139.


26 Smith KL, McNeill JJ. The Emergency Medical Response Steering Committee. Cardiac arrests treated by ambulance paramedics and fire fighters. Medical Journal of Australia. 2002;177:305-309.


27 Stiells IG, Wells GA, Field BJ, et al. Improved out-of-hospital cardiac arrest survival through the inexpensive optimization of an existing defibrillation program. Journal of American Medical Association. 1999;281:1175-1181.


28 Stiell IG, Wells GA, Field B, et al. Advanced cardiac life support in out-of-hospital cardiac arrest. New England Journal of Medicine. 2004;351:647-656.


29 Le May MR, Davies RF, Dionne R, et al. Comparison of early mortality of paramedic-diagnosed ST-segment elevation myocardial infarction with immediate transport to a designated primary percutaneous coronary intervention center to that of similar patients transported to the nearest hospital. American Journal of Cardiology. 2006;98:1329-1333.


30 Morley PT, Walker T. Australian Resuscitation Council. Australian Resuscitation Council: adult advanced life support (ALS) guidelines 2006. Critical Care and Resuscitation. 2006;8:129-131.


31 Madsen CD, Pointer JE, Lynch TG. A comparison of adenosine and verapamil for the treatment of supraventricular tachycardia in the prehospital setting. Annals of Emergency Medicine. 1995;25:649-655.


32 Stiell IG, Spaite DW, Field B, et al. Advanced life support for out-of-hospital respiratory distress. New England Journal of Medicine. 2007;356:2156-2164.


33 Howell MA, Guly HR. A comparison of glucagon and glucose in prehospital hypoglycaemia. Journal of Accident Emergency Medicine. 1997;14:30-32.


34 Kelly AM, Kerr D, Dietze P, et al. Randomised trial of intranasal versus intramuscular naloxone in prehospital treatment for suspected opioid overdose. Medical Journal of Australia. 2005;182:24-27.


35 Kane KE, Cone DC. Anaphylaxis in the prehospital setting. Journal of Emergency Medicine. 2004;27:371-377.


36 Vilke GM, Sharieff GQ, Marino A. Midazolam for the treatment of out-of-hospital pediatric seizures. Prehospital Emergency Care. 2002;6:215-217.



26.2 Retrieval






Introduction


Retrieval medicine is a term used to describe the branch of emergency medicine involved with the retrieval and transport of patients from remote locations to primary hospital treatment sites. Retrieval is the process whereby medical teams are transported from central hospitals to peripheral areas with the intention of treating, stabilizing and transporting patients back to these centres. The most common form is a secondary retrieval where the patient is transferred from one healthcare facility to another. A primary retrieval is where the patient is retrieved direct from the scene or incident. However, the clinical distinction between primary and secondary retrieval becomes less clear in smaller healthcare settings where staff are unfamiliar with management of critically ill or injured patients.


Retrieval is more than simply retrieving patients. The process more importantly encompasses the transportation of personnel and expertise from a tertiary centre to a peripheral location. It would not be cost-effective to place specialists from every field in every rural location even if the workforce was available. In addition, the volume of suitable work in each location would be insufficient to adequately maintain specialist skills. Transporting specialist services to the rural patient when needed is more economical than supplying each rural area with a fixed, dedicated specialist service and allows these specialists to maintain skills. The general concepts of a retrieval service also include provision of rural areas with an information and advice network that can be accessed at any time, a bed-finding facility at receiving institutions and activation of the retrieval team when required. The rural practitioner therefore has the capacity to gain expert advice or the means for transporting patients when necessary from a single phone call. The alternative of the remote practitioner having to make multiple phone calls to find a bed as well as simultaneously managing the patient is not an accepted standard of care. This provision of an information and support network is more essential than the transport itself. The term ‘retrieval’ unfortunately focuses upon the transport itself, distracting from the other vital system components.





Modes of transport


The mechanism by which the medical team is transported varies with individual circumstances. Road transport is the most readily available and requires the least resources. Transport by helicopter is more expensive and takes time to activate but enables greater distances to be covered in a shorter time period. If helicopters can land at each location there is no need for secondary ambulance transfers. Fixed-wing aircraft share similar drawbacks, can cover even greater distances but require special landing strips and the need for secondary transfers to and from airstrips. Loading and unloading patients in appropriately configured aircraft is almost identical to land ambulance transfers. Issues specific to altitude will be addressed later.


When road transport can be achieved in less than 1–2 h this is normally the cost-effective choice. Transport by air has the disadvantages of increased cost and problems associated with altitude. The greatest benefit of aerial transport is in reducing the time spent in transit and therefore minimizing the time at greatest risk. Figure 26.2.1 shows the time differences between road and helicopter transport. Overall time from incident to arrival at a central hospital may not be significantly reduced by use of a helicopter if road transport is immediately available. The time spent in transit, however, and therefore the time the patient is exposed to maximum risk is significantly reduced. The time taken for the retrieval team to reach a patient is also minimized by use of helicopter transport where road distances are prolonged. The choice between helicopter and fixed wing is a balance between avoiding secondary transfers with helicopters and more rapid flight with fixed wings. Beyond helicopter flight times of 1 h (~250 km), fixed wing becomes increasingly preferable. Helicopter use beyond 400 km is unusual. The transport distance, terrain covered and the specific condition of the patient all influence the decision on the mode of transportation. It is inappropriate to transport some patients by air whilst others require pressurization to ground level in order to be transported safely. The final decision will rest with the retrieval team familiar with the options available. The team should be contacted early in order to arrange the most appropriate transport as quickly as possible.




Preparation for transport


It is very difficult to perform even simple tasks in a moving vehicle. Planes and helicopters are particularly noisy, with unexpected movements and light fluctuations. Listening to heart sounds, respiratory sounds or even taking a pulse may be impossible. Despite this there are several examples in the literature of the successful performance of intubation, i.v. cannulation and other procedures in aircraft.2,3 Although this is reassuring, it should be considered a failure of pre-flight preparation to be put in the position where such a procedure becomes necessary in transit. If a procedure is considered to be likely or possibly needed before arrival at the destination, serious consideration should be given to performing that procedure prior to departure. It is essential to have lines secured, redundant lines operational in case of emergencies and contingency plans prepared for common and potentially serious complications. In practice this means checking that each vascular access is patent, operational and sufficiently secured to withstand sudden turbulence. Some lines may require suturing to achieve this. It is prudent to have at least one i.v. line that is patent but not in use in order to provide access in an unexpected emergency. Wherever practicable, a single port at a secure site can be used for several infusions, thus freeing up other ports.


Conscious patients should be asked how they feel about aerial transport as early as possible. Urinary catheters may be needed for long flights if patients are unable to void before or likely to need to do so in flight. Antiemetics should be administered early and anxious patients may require sedation. Unconscious patients require gastric and urinary catheterization and confirmation of position, and the patency and security of endotracheal tubes and other invasive devices must be checked before departure. Medical gases are dry, and heat–moisture exchangers or other forms of humidification for ventilated patients are essential to reduce tube occlusion from dried secretions.


Restless, anxious or combative patients are a danger to themselves and everyone else in the confines of an ambulance or aircraft. Sedation should be liberally used. It may even be necessary to intubate some patients for safety reasons prior to departure. Careful discussion with conscious patients prior to departure will usually reveal anxieties related to air transport. Reassurance and pharmacotherapy are more effective the earlier they are given.


Patient comfort in transport is important. The type of mattress used should be considered well in advance. The most comfortable and practical solutions are beanbag-filled vacuum mattresses. Multiple commercial brands are available, all sharing the same design characteristics. The mattresses are insufflated with air and the patient is allowed to settle in comfortably. Air is then evacuated by wall suction or with a hand pump whilst the mattress is moulded to the patient. Moulding to the head and neck and around splinted limbs is possible. Most mattresses are covered in waterproof material, have handles for ease of transfer and are radiolucent. Plain radiography and computerized tomography (CT) scanning can be performed without the need to transfer the patient. The stiffness of the evacuated mattress and the carry handles may make transfer for procedures such as CT scanning easier than with conventional methods. Some emergency departments use these vacuum mattresses routinely in major resuscitation bays.


A final check with the patient and relatives is wise prior to departure. Contact details for and of significant others as well as informed estimations of arrival times help to reduce communication difficulties. Time should be set aside for answering any questions prior to departure. Written information detailing where the patient is to be taken, the names of the transporting crew and phone numbers for further information relieves much anxiety on the part of relatives and friends.



Common problems in transit


Estimating transport time is difficult. Assumptions by non-transport personnel are generally half to one-third of actual times. Considerable time is required for familiarization with the patient and in transferring from one transport modality to the next. Hasty transfers without adequate familiarization increase complications. Oxygen supplies are crucial in longer transports. The amount needed should be calculated to last for at least twice and preferably triple the estimated journey time. If a minimum supply only is taken, any complication or delay may prove fatal. It is also wise to have several cylinders and a spare regulator as a safeguard in the event of equipment failure.


Monitoring and equipment used in transport should be in accordance with recommended standards. Detailed guidelines are available.1 Most patients require continuous ECG, pulse oximetry and blood pressure monitoring as a minimum. Equipment must be selected carefully. Display screens must be visible in daylight and battery life must be appropriate for duration of transport with a large capacity for additional work. It should always be assumed that the next task will occur immediately without the opportunity to recharge batteries. Consideration should be given to the placement of invasive lines for potentially unstable patients. Use of arterial lines significantly reduces battery requirements for non-invasive blood pressure monitoring. Equipment alarms must be clearly visible as auditory alarms are difficult or impossible to hear in moving vehicles, especially helicopters.


Infusions may be delivered by pumps or syringe drivers. Infusion pumps are more accurate and are essential for critical infusions such as inotropes. However, they are relatively heavy and require specific tubing. Syringe drivers are lighter and require no specialized tubing. However, they are less accurate, must be shielded from sunlight to prevent rubber plungers drying and seizing when exposed and therefore should only be used for less critical infusions.


Loading and unloading are critical times. The combination of patient, stretcher and equipment can be very heavy. Injuries to patients and personnel may occur unless extreme care is taken. Equipment and lines can be damaged or dislodged. The concentration required easily distracts attention from the patient, monitor alarms may not be heard and critical incidents can occur most easily at these times. For all these reasons transfers are considered the most at-risk time for the patient. Reducing the number of transfers is a priority in care.


Defibrillation in moving vehicles creates some special problems. Movement artefact may make it impossible to synchronize for cardioversion or may make rhythm interpretation difficult. Positioning and operating a standard defibrillator can be almost impossible in a moving vehicle. Patients should be assessed prior to departure for likelihood of the need for defibrillation in-flight and this possibility discussed with the pilot. High-risk patients, such as those with acute myocardial infarction or those with known arrhythmias, can be prepared before the journey. All contact with metal should be avoided by wrapping the patient in blankets and sheets, with special attention paid to stretcher edges. Self-adherent defibrillation pads should be applied to the thorax prior to transport. This improves signal quality as well as providing good insulation. A major problem is with residual current leakage. If DC shock is indicated in-flight the pilot must be consulted prior to any attempt. Current leakage and microshocks have the potential to damage and disable electronic equipment. The pilot may elect to allow the DC shock, to turn off electronic equipment first or not permit the procedure. The final decision in these circumstances is a balance between the treatment of the patient and the safety of the aircraft and crew. Only the pilot can make this decision. A pre-informed pilot may be able to avoid situations where defibrillation would be denied.



Special problems associated with travelling at altitude


All transport is associated with motion sickness. Staff tend to become accustomed whilst first-time travellers (including patients) are most affected. Antiemetics should be discussed and administered early whenever possible. Another related condition reducing performance of medical attendants is the sopite syndrome. This condition is characterized by yawning, drowsiness, disinclination for either physical or mental work and lack of participation in group activities.4 It is not directly related to the degree of turbulence, is not responsive to anti-motion-sickness medications and, unlike motion sickness, there appears to be little adaptation with time. As many as two-thirds of air attendants are affected to some degree, making this condition an important cause of reduced performance during transport.5


Travelling at altitude exposes patients and crew to reduced atmospheric pressure. The two most important consequences of this are hypoxia and expansion of gases. Most fixed-wing aircraft can pressurize the interior of the craft to sea level or above, making these complications avoidable. Medical helicopters do not have the option of pressurization but may elect to fly at low altitudes. Pressurization to sea level causes excessive fuel demand and additional stress on the aircraft. As a compromise, most commercial and medical aircraft will pressurize to an equivalent altitude of 5000–7000 ft whilst travelling at 30 000–40 000 ft. At this cabin altitude ambient PO2 is reduced to 60 mmHg and trapped gases expand by one-third of their volume. Breathing cabin air produces an Sa–O2 of 90% under these conditions. For healthy individuals this poses no problem. For unwell or oxygen-dependent patients, however, being on the shoulder of the Hb–O2 dissociation curve can be dangerous with only small decreases in PO2 from this point inducing large falls in Sa–O2. Supplemental O2 or increased pressurization may be required.


Expansion of trapped gas can produce disastrous consequences. All pneumothoraces, no matter how small, require venting prior to elevation to altitude. Heimlick valves are preferable to underwater seal drains during transport as underwater seal apparatus is disturbed by movement and is at greater risk of damage and breakage. Air trapped in small bowel (for instance in ileus) can produce considerable discomfort. Gas at either end of the gastrointestinal tract can vent spontaneously. Middle ear gas can be particularly painful on ascent and descent. Patients should be taught equalization techniques such as the Valsalva, Frenzel or Toynbee manoeuvres. The Valsalva manoeuvre reduces cardiac venous return and may be associated with syncope. The most effective technique is the Frenzel manoeuvre, which is carried out with the mouth, nostrils and epiglottis closed. Air in the nasopharynx is then compressed by the action of the muscles of the mouth and tongue. This technique not only generates higher nasopharyngeal pressures than the Valsalva manoeuvre, it opens the eustachian tubes at lower pressures. The easiest taught technique is the Toynbee manoeuvre, which raises pharyngeal pressure by swallowing with the mouth closed and nostrils occluded. In babies and young children, the angle of entry of the eustachian tubes into the nasopharynx is less acute and hence ear problems in flight are less common. Older children and some adults are unable to learn the various techniques.6 Nasal decongestants prior to departure or sweets to suck on during descent may be of benefit. If a patient is unable to clear the ears, pain increases until the tympanic membrane ruptures with sudden relief of discomfort.


Expansion of gases has consequences for medical equipment. Air in an endotracheal tube cuff expands, increasing cuff pressure on ascent. Although modern high-volume, low-pressure cuffs minimize this effect, the increased pressure may cause tracheal damage if left unchecked for long periods. On descent the volume falls, making tube displacement more likely and increasing the likelihood of leakage around the cuff. Loss of ventilatory volumes and aspiration may result. The cuff pressure should be monitored on ascent and descent and adjusted as necessary. An alternative practice is to fill the cuff with sterile fluid such as normal saline. This makes it impossible to monitor the pressure in the cuff and is not necessary if the air-filled cuff is monitored appropriately.


Ascent to altitude may cause or increase the symptoms of decompression illness. The use of portable hyperbaric chambers or pressurization to sea level may be required. In aircraft where pressurization is not possible the lowest safe altitude is the next best alternative. These requirements must be discussed with the pilot as soon as they are known and certainly well prior to departure.




Future directions


Medical equipment is becoming more complex as well as smaller and lighter. Sophisticated ventilators, multilumen infusion devices and complicated equipment such as intra-aortic balloon pumps can already be transported in surface and aerial craft. Non-invasive pressure-monitoring equipment has been developed, enabling beat-to-beat measurement of arterial and other pressures and real-time cardiac output monitoring. This evolution of equipment will continue, making it possible to transport increasingly complex cases with greater safety and less need for invasive interventions.


The capacity for interactive communication with remote areas is increasing at an accelerated rate. Multimedia communications allow teleconferencing, data transmission of electrocardiograms, and radiological images and video viewing of patients with increasing clarity. Pilot systems have already been developed whereby surgeons can perform operations with the aid of video cameras and remote control devices without the need to leave the central institutions. The further development of this technology will greatly reduce the need to transfer patients and allow comprehensive management in rural locations.





26.3 Medical issues in disasters






Introduction


Disaster preparedness and response involve a complex, multidisciplinary process of which emergency medicine comprises one component. Government agencies, fire fighters, law enforcement, ambulance services, civil defence, the Red Cross and other aid organizations may all have a role to play. The health and medical management of disasters can also cut across professional disciplines and require contributions from emergency medicine, public health, primary care, surgery, anaesthetics and intensive care.


From the health perspective, different types of disasters are frequently associated with well-described patterns of morbidity and mortality. The clinical and public health needs of an affected community will, therefore, also vary according to the type and extent of disaster. Emergency physicians should understand the health and medical consequences of the various types of disasters in order to determine their own roles in preparedness and response. In practice, emergency physicians will be most actively involved in the response to an acute-onset disaster that involves multiple casualties, such as a transportation incident. Several other types of disasters, including floods and cyclones, are generally associated with few, if any, casualties. The health and medical needs in these settings usually involve augmenting public health and primary-care services.


The aims of this chapter are to familiarize emergency physicians with disaster epidemiology and disaster management arrangements, and to provide an overview of the medical response to a disaster involving multiple casualties. While the chapter focuses on health and medical issues, it should be remembered that the effects of disasters are often widespread and long term. Disasters cause significant social, economic and environmental losses that can have a devastating effect on the general wellbeing of the affected community.



Definitions and classification


There is no internationally accepted definition of disaster or disaster classification. There are, however, increasingly consistent uses of terms among stakeholder organizations. Common to most definitions is the concept that following a disaster the capacity of the impacted community to respond is exceeded and there is, therefore, a need for external assistance. The World Health Organization characterizes a disaster as a phenomenon that produces large-scale disruption of the normal healthcare system, presents an immediate threat to public health and requires external assistance for response. The Australian Emergency Manual defines disaster as an event that overwhelms normal community and organizational arrangements and requires extraordinary responses to be instituted. The Center for Research on the Epidemiology of Disasters (CRED), which compiles the data behind the annual World Disasters Report of the International Federation of Red Cross and Red Crescent Societies, stipulates a quantitative surveillance definition involving one of the following: 10 or more people killed, 100 or more people affected, declaration of state of emergency or an appeal for international assistance.1


Disaster management is the range of activities designed to establish and maintain control over disaster and emergency situations, and to provide a framework for helping at-risk populations avoid or recover from the impact of a disaster. It addresses a much broader array of issues than health alone, including hazard identification, vulnerability analysis and risk assessment. Disaster medicine can be defined as the study and application of clinical care, public health, mental health and disaster management to the prevention, preparedness, response and recovery from the health problems arising from disasters.2 This must be achieved in cooperation with other agencies and disciplines involved in comprehensive disaster management. In practice, emergency medicine and public health are the two specialties most intimately involved in disaster medicine.


A mass casualty incident is an event causing illness or injury in multiple patients simultaneously through a similar mechanism, such as a major vehicular crash, structural collapse, explosion or exposure to a hazardous material.


Disasters are commonly classified as natural versus technological/human-generated (Box 26.3.1).1 Disasters may also be classified according to other characteristics, including acute versus gradual onset, short versus long duration, unifocal versus multifocal distribution, common versus rare and primary versus secondary. Classifications of disaster magnitude exist for selected natural hazards, such as earthquakes and hurricanes/cyclones; however, there is currently no standard classification of severity of disaster impact.




Epidemiology


Globally, the types of disasters associated with the greatest numbers of deaths are complex emergencies (CEs). These are crises characterized by political instability, armed conflict, large population displacements, food shortages and collapse of public health infrastructure. Because of insecurity and poor access to the affected population, aggregate epidemiological data for CEs are somewhat limited. However, between 1998 and 2004 in the eastern region of the Democratic Republic of Congo, 3.9 million people lost their lives due to the consequences of the major humanitarian crisis afflicting that country.3 Incredibly, this was more than three times the total number of deaths globally due to natural and technological disasters during the decade of the 1990s. Based on United Nations definitions, there were 27 ongoing CEs in 2007, involving over 30 countries and impacting on the lives of hundreds of millions of people.4 Thirteen (44%) of these crises were ongoing in Africa, with 10 (37%) occurring in Asia.


According to information compiled by the International Federation of the Red Cross, there has been a significant increase in the total number of natural and technological disasters worldwide during the past 30 years. From 1996 to 2005, an average of approximately 641 such disasters was documented annually, peaking at 801 in 2000. While the total number of people killed by natural and technological disasters is approximately 93 000 per year, there is a wide annual range (21 888 in 2000 to 251 768 in 2004 due to the Indian Ocean tsunami). Moreover, the total number affected has almost trebled over the past three decades. It is estimated that approximately 250 million people are directly affected on an annual basis. Selected data are presented in Figures 26.3.1 and 26.3.2.




The commonest types of disasters across the globe are transportation incidents, floods, windstorms, industrial incidents, building collapses, droughts/famines and earthquakes/tsunamis (see Fig. 26.3.1). Asia is the region of the world most prone to natural and technological disasters, recording 41% of such incidents between 1996 and 2005. It is followed by Africa (22%), the Americas (20%), Europe (14%) and Oceania (3%). Compared with other regions of the world, Australasia and Oceania clearly have a relatively low incidence of disasters. Over the past 10 years the commonest causes of natural disasters in Australia have been floods, severe storms and cyclones. Nationally, an average of 33 lives are lost per year due to disasters in Australia. In addition, over 68 000 people are affected annually, through injury, displacement, financial loss, damage or loss of homes and businesses. Historically, the leading causes of death from natural disasters have been heatwaves, followed by cyclones, floods and bushfires. Human-generated disasters resulting in multiple casualties have occurred more frequently in Australia in recent years. The commonest causes of mass casualty incidents have been bus crashes, structural fires, mining incidents, aviation incidents and train crashes.


The impact of disasters has been less in New Zealand, where only 28 lives were lost among 9040 persons affected over the last decade. The pattern of natural disasters also differs, with the commonest major events being floods, earthquakes and landslides. The North Island of New Zealand has six active volcanoes, with the last attributed loss of life occurring in 1953.


Data reporting on the incidence of terrorism has recently been complicated by changing definitions and political motivations of the reporting agencies. In spite of the controversies and complexities surrounding the reporting, the number of international terrorist attacks has increased significantly since 2000, following a steady decline during the latter half of the 1990s.5 There were on average 229 international terrorist attacks between 1997 and 2006, with a peak of 395 in 2004. Over that period, an average of 694 persons per year were killed, with a peak of 3184 in 2001 (including 2982 deaths due to the September 11 attacks by Al Qaeda in the USA). This is just a very small fraction of the total number deaths attributed to natural and technological disasters and CEs. The regions documenting the highest number of international terrorist attacks over that period have been the Middle East (51%), Western Europe (13%), South Asia (11%), Africa (6%), and Southeast Asia and Oceania (4%).


Disaster epidemiology globally, including the Australasian region, is being impacted by climate change. Global warming has already been associated with an increase in the frequency and unpredictability of weather-related disasters, such as heatwaves, floods and droughts. There is also evidence of increased intensity of tropical cyclones,6 as has been reflected by recent experience with hurricane Katrina (2005) and cyclone Larry (2006). Rising temperatures have already been implicated in the spread of infectious disease vectors, including malaria-carrying mosquitoes. Other important diseases are also sensitive to changing temperatures and rainfall, including dengue, malnutrition and diarrhoea. The health-related and other impacts of climate change will not be evenly distributed. Disasters associated with global warming are particularly likely to threaten the lives and livelihoods of coastal communities, those living in low-lying islands (e.g. due to rising sea levels), and in arid and high mountain zones.



Socioeconomic impact


Disasters have the potential for major socioeconomic impact, costing the international community billions of dollars annually. In developing countries, years of development work and investment can be devastated by a single disaster. During the 10 years to 2005, disasters caused a global average of approximately US$73.4 billion damage per year. Windstorms were the costliest disaster over the decade, accounting for 43% of disaster-associated costs, led by hurricane Katrina at US$125 billion, which caused 40% of all windstorm damage. Terrorist attacks on major financial centres, such as the World Trade Center in New York have demonstrated the potential for tens of billions of direct economic impact, enormous social consequences and political repercussions for mismanaged disaster response. These figures may be overshadowed by pandemic disease, such as from avian influenza, for which economic cost estimates range to upwards of US$1 trillion.7


In Australia, disasters have cost an average of A$ 1.14 billion annually. Over the past 30 years, floods, storms, then cyclones have caused the greatest disaster-related economic losses in Australia. The most economically costly disasters were cyclone Tracy (1974), the Newcastle earthquake (1989) and the Sydney hailstorm (1999).


Economic estimates, of course, are unable to reflect the true scale of human suffering associated with disasters. While we can often document the mortality, morbidity and financial losses associated with disasters, it is impossible to quantify the associated personal, psychological, social, cultural and political losses.



Disaster management/emergency management


As emergency physicians play a vital role in the medical aspects of disaster management, they should be familiar with the four underlying concepts on which these arrangements are based.







Disaster planning


Disaster planning is the process by which a community develops a comprehensive strategy to effectively manage and respond to disasters. It is a collaborative effort that requires cooperation between government agencies, community services and private organizations. The ultimate goals of the planning process include clarification of the capabilities, roles and responsibilities of responding agencies, and the strengthening of emergency networks. Other operational issues, such as emergency communications and public warning systems, will also be addressed.


A critical concept in disaster planning is the graduated response. The initial response to an event begins at the local level. More resources can subsequently be requested from regional, state or national levels, as required, to supplement those of the local providers. Compatibility between plans at the different levels is therefore necessary. A hierarchy of disaster management plans exists in which plans at lower levels dovetail with those of the next highest level. Command and control arrangements, as well as the roles and responsibilities described in a particular plan, must be compatible with the other plans to which it relates. Emergency physicians must be aware of these requirements if they are to constructively contribute to the development of state, regional and hospital disaster plans.


Several high-profile terrorist events (e.g. World Trade Center attack in New York) and important gatherings (e.g. APEC Leaders Meeting in Sydney) have highlighted the need for specific planning for terrorist events. Such planning will frequently involve collaboration with relevant military, security and intelligence agencies, and a consideration of the tactics used by terrorists. Over the past decade 73% of international terrorist attacks have used conventional weapons, including explosives and small arms. Other terrorist tactics include assassinations, hijacking and kidnapping. Unconventional attacks, including those that using jet airliners as weapons of mass destruction, or chemical, biological and radiological weapons have constituted only 0.5% of international terrorist attacks. Nonetheless, prudent planning for these types of incidents is also required, observing the all-hazards approach.


Disaster exercises must be conducted regularly to test the response and recovery aspects of the plan. Exercises range from desktop simulations to realistic scenarios with moulaged patients in the field. If conducted appropriately, they should effectively test whether the objectives of the plan have been met and provide the opportunity for disaster response training. Disaster planning is a continuous process, and plans need to be regularly reviewed and updated. Disaster exercises may provide insights into areas in which the plan needs to be improved.


Planning and responding for international disasters have become more relevant for Australasian health professionals in light of the recent terrorist attacks in Bali (2002 and 2005), the Indian Ocean tsunami (2004) and the earthquake in Pakistan and India (2005). Such planning and response can be advised by the internationally recognized Sphere Minimum Standards in Disaster Response8 and in collaboration with important international agencies, such as the United Nation’s Office for Coordination of Humanitarian Affairs. Sphere specifies standards in six sectors of disaster response: water and sanitation, food security, food aid, nutrition, shelter and health services. These standards are relevant for all disasters and represent an extremely useful reference to guide planning and response for domestic incidents as well.



Disaster response activities



Incident management



Scene assessment and stabilization


The initial scene assessment will be conducted by first responders, such as police or ambulance personnel. It is important for the first medical responder, generally an ambulance officer, to rapidly report findings to the Ambulance Communications Centre. An accurate, timely assessment is critical to initiating an appropriate and effective response. Key information that should be related from the scene includes the nature and magnitude of the disaster, the presence of ongoing hazards, the estimated number of deaths and injuries, the need for further assistance, and the most appropriate routes of access to the scene. In large-scale disasters that affect entire populations, such as cyclones or earthquakes, a rapid health assessment followed by broader epidemiological assessments will be required, including an evaluation of the impact on the health infrastructure, public utilities and shelter.


Site security and safety procedures must be observed to ensure that rescuers and bystanders do not become victims. This is particularly relevant when a terrorist incident is suspected because of the threats posed by a secondary attack on responders or the potential use of weapons of mass destruction. The police should establish a perimeter around the scene of a multiple casualty incident and allow access only to authorized personnel. If a hazardous material is involved, rescuers may be required to wear specialized personal protective equipment to protect their airways, eyes and skin. Electrical hazards, fires, explosions, leaking gases and unstable structures may all pose significant threats to rescue personnel. These hazards must be eliminated or controlled prior to initiating rescue operations.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on 26: Emergency Medical Systems

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