Airway management
There are multiple devices designed to assist in the prehospital management of the patient’s airway and breathing. Rescuers at all levels are trained in the use of the bag-valve-mask (BVM) device and both the nasopharyngeal airway (NPA) and oropharyngeal airway (OPA). The NPA and OPA are curved pieces of plastic that are inserted blindly, provided there are no contraindications.
They are used chiefly to maintain airway patency.
Rescuers either not trained in endotracheal intubation or unable to achieve tracheal intuba- tion with direct laryngoscopy may use the PTLA (Figure 7.1) or Combitube (Figure 7.2) for a patient
with airway compromise. The PTLA and Com- bitube are similar devices (with multiple tubes bound together) designed for blind insertion into the patient’s airway. Their success depends on the operator being able to correctly identify which of the blindly-inserted tubes ends up in the esophagus, and which tube can adequately ventilate the trachea. The LMA (Figure 7.3) was first introduced in the operative setting in the late 1980s as an alternative to endotracheal intub- ation for selected patients, but has increasingly been used as an alternative when endotracheal intubation cannot be achieved. The device con- sists of an inflatable V-shaped diaphragm at the end of a large-bore tube that is placed blindly into the larynx. It is relatively easy to use and minimizes the risk of gastric insufflation during assisted ventilation. It does not, however, protect the trachea from aspiration of blood or vomitus.
Endotracheal intubation (ETI) remains the gold standard for airway protection, though this technique is most dependent on operator skill and patient factors. Many factors common in prehos- pital care can make oral ETI difficult or impos- sible: operator’s inexperience, inadequate patient sedation or relaxation, blood or vomitus in the airway, and anatomic variables such as an anterior larynx or expanding neck hematoma. Outside of investigational protocols, oral ETI is attempted in the prehospital setting only by rescuers with paramedic training or above. Blind nasotracheal intubation (BNTI) may be attempted for patients
Inflation valve and adaptor – both cuffs inflated simultaneously
Inflation line to proximal cuff
Inflation line to distal cuff Stylet in long tube
Short tube
Teeth strap
Proximal cuff Distal cuff
Distal end of short tube Figure 7.1
Pharyngotracheal lumen airway (PTLA). Reproduced from D. Skinner et al, Cambridge Textbook of Accident and Emergency Medicine, Cambridge, Cambridge University Press, 1997.
Prehospital care and emergency medical services
Figure 7.3
Laryngeal Mask Airway. (a) LMA in place with cuff overlying larynx. (b) LMA placement into the pharynx. (c) LMA placement using the index finger as a guide. Reprinted from Clinical Procedures in Emergency Medicine, 4th ed., Eds Roberts JR, Hedges J, page 62, Copyright 2003, with permission from Elsevier.
No.2 No.1
No.1
No .2
No.2 No.1
Figure 7.2
The Combitube. Reproduced from D. Skinner et al, Cambridge Textbook of Accident and Emergency Medicine, Cambridge, Cambridge University Press, 1997.
(a) (b) (c)
who still have spontaneous respiratory effort but need definitive airway control. This technique is of greatest use when orotracheal intubation is either not possible or very unlikely to succeed due to anatomic or traumatic reasons. The BNTI tech- nique, uncommonly utilized at receiving trauma centers, is employed more frequently in the pre- hospital setting when neuromuscular blockade is not available, and jaw clenching prevents oral intu- bation. BNTI is contraindicated in patients with significant facial trauma. While neuromuscular- blocking agents (paralytics) are an integral com- ponent of rapid sequence intubation (RSI) in the hospital, historical concerns exist about their
use by prehospital personnel. These providers may only infrequently intubate and, if unable to intubate or ventilate a previously spontaneously- breathing patient, have severely limited access to rescue techniques. Many helicopter transport ser- vices have reported high rates of successful intub- ations (96%) using paralytics, but in general they employ a very select and experienced group of practitioners. Some ground transport services have also reported high success rates (94%) using paralytics, but most frequently this is in high-volume urban areas under very close medical direction. At the current time, the use of paralytics (and concomitant induction agents) to facilitate
intubation should only be allowed in systems with highly-trained and experienced providers operating under tight medical control; sufficient backup and rescue techniques must be available in the event of failed ETI.
Approximately 70% of US ground paramedics and all air medical paramedics are allowed to perform some form of surgical airway access if needed. Skills range from needle cricothyrotomy with jet ventilation, to the use of percutaneous kits that employ the Seldinger technique (such as the Melker kit), to open cricothyrotomy. The need for cricothyrotomy in the field is fortunately infrequent. Surprisingly, given the lack of experi- ence, reported success rates in the field are high (82–100%). All systems employing the use of par- alytics must equip and train their providers to perform a surgical airway in the event of failed intubation and ventilation.
Intravenous access and fluid administration Paramedics and EMT-Is should attempt IV access on all unstable or potentially unstable patients in the field. Many life-saving medications are most effective, or only available, when administered IV.
Furthermore, IV crystalloid infusion remains the cornerstone of management of hypotension in the field. When possible, every trauma patient should have two large-bore (e.g., 14- or 16-gauge) IV catheters placed in the field. However, attempts at cannulation have been reported to add as much as 12 minutes to on-scene times. Rescuers must not delay transport when adequate access has not been obtained. For most patients, the appropriate rule of thumb is two attempts per provider, ideally during transport of the patient. In 1994, a prom- inent Houston study reported that aggressive pre- hospital fluid resuscitation of hypotensive victims of penetrating trauma did not improve survival and actually increased total blood loss when com- pared with delayed resuscitation in the hospital.
The results of this study and its applicability to other settings are still debated. However, this remains an area of ongoing research interest, so prehospital providers and physicians developing EMS protocols should be cognizant of the need to avoid over-resuscitation (with concomitant risk of increased hemorrhage) and under-resuscitation (with attendant risk of hypoperfusion). Transport time and time to definitive control of suspected hemorrhage are important factors to consider when choosing to begin prehospital fluid resusci- tation. Not all parameters will consistently be improved by fluid administration (e.g., altered
mental status in the head-injured patient), and providers must exercise judgment as to the ade- quacy and appropriateness of their resuscitation.
Cardiac monitoring and defibrillation
Early defibrillation is critically important for patients with non-perfusing ventricular tachycar- dia or ventricular fibrillation, since survival for these patients decreases by 10% per minute. With the advent of AEDs, most first responders and EMT-Bs who arrive on scene before paramedics can now defibrillate pulseless patients in ventricu- lar fibrillation or ventricular tachycardia. How- ever, rhythm interpretation and the decision to cardiovert borderline perfusing rhythms remain solely within the scope of ALS. Many paramedics are now trained to perform and interpret 12-lead electrocardiograms (ECG); some have the capabil- ity of radio transmission of the ECG to the hospital.
Multiple studies have demonstrated that well- trained paramedics have excellent accuracy for both rhythm recognition and detection of ST- segment elevation in acute coronary syndromes.
Such skills are critical for proper application of the American Heart Association’s Advanced Cardiovascular Life Support (ACLS) guidelines.
Medication administration
Although certain states allow EMT-Bs to admin- ister one or two selected life-saving medications such as glucose, epinephrine, or albuterol, most BLS providers cannot administer medications. In general, only paramedics may administer medica- tions. Paramedics are equipped with medicines to treat pain, selected overdoses, hypoglycemia, bronchospasm, allergic reactions, hypotension and cardiac ischemia, and follow all ACLS protocols.
Certain ALS systems may carry paralytic agents to facilitate intubation at the discretion of the state and local medical directors. Field medication use, especially with controlled substances and with potentially pro-arrhythmic agents, must be tightly monitored and subject to regular quality assurance by the medical director.
Needle decompression
Most paramedics are permitted to perform chest decompression in the patient with suspected ten- sion pneumothorax. Signs suggestive of tension pneumothorax include tachypnea, hypoxia, uni- lateral decreased or hyper-resonant breath sounds, jugular venous distention, and deviation of the
Prehospital care and emergency medical services
trachea away from the affected side. Needle decompression is indicated for a patient in severe distress with the above signs or in cardiac arrest following trauma.
Immobilization
All EMS personnel are trained in the proper tech- nique for spinal immobilization of patients (Figure 7.4). An appropriately-sized, rigid cer- vical collar should be placed on every victim of trauma with potential for spinal injury, including
patients with pain, tenderness, or a suspicious mechanism of injury. However, since the cervical collar alone does not provide adequate immobil- ization for transport, patients should also be sta- bilized with a rigid backboard and some form of lateral stabilization (such as foam blocks) secured with straps or tape. Special steps, such as the use of a towel roll under the shoulders, may need to be taken to maximize head position (i.e., prevent flexion) in pediatric patients. Pregnant patients should have the right side of the backboard ele- vated 30° to keep the uterus off the inferior vena cava. This is done to avoid hypotension and fetal hypoperfusion. Patients with gunshot wounds to the neck, thorax, or abdomen not meeting the crite- ria above are not at increased risk for occult spinal injury and therefore do not need full immobiliza- tion on a backboard. Placement of a patient on a backboard is not innocuous; studies have shown that pressure-mediated skin damage can begin to develop after as little as 30 minutes on a backboard.
The Kendrick extrication device (KED) is made up of a series of parallel splints longitudinally bound together in a vest-like device that provides
assistance with spinal stabilization during the extrication of a trauma patient from an enclosed space, such as a motor vehicle. It does not provide full spinal immobilization, and therefore cannot be used in lieu of a backboard for adults. Due to its wrap-around nature, however, it may be use- ful for pediatric patients who cannot or will not lie still on a standard backboard.
Patients with unstable vital signs should have only the injured extremities immobilized which have the potential to cause further hemorrhage if moved (i.e., pelvis and long bones, especially suspected femur fractures). Angulated extremity fractures should be carefully evaluated for distal neurovascular status. Currently, most prehospital jurisdictions call for traction splinting of suspected femur fractures, but this is subject to debate. These devices require time for application, are of debat- able benefit in the field, and have contraindications (e.g., pelvic fracture) which may be unapparent.
Any patient with an angulated fracture of any extremity with absent distal pulses should have in-line traction applied and be splinted. All other suspected fractures should be immobilized in the position of greatest comfort for transport.
Pneumatic anti-shock garment /military anti-shock trousers
Developed during the Vietnam War to treat sol- diers exsanguinating in the field, the pneumatic anti-shock garment (PASG) was a mainstay of prehospital trauma care for nearly 20 years until its use was called into question by two outcome stud- ies in the 1990s. Formerly known as the military anti-shock trousers (MAST), this device consists of a set of nylon pants with separately inflatable leg and abdominal sections that attach to a manual pump with a pressure gauge. Currently, the litera- ture does not support the use of the PASG in pen- etrating trauma. There is some reason to believe that the PASG may be a useful immobilization device for pelvic fractures and/or femur fractures.
Use in blunt trauma patients with severe hypoten- sion is still debated, but it is used in some regions for this indication. The PASG is contraindicated in patients who are pregnant or who have pul- monary edema, evisceration of abdominal organs, cardiac tamponade, or cardiogenic shock.
Wound care
All EMS providers are trained to control external hemorrhage with direct pressure and elevation of the injury above the heart. Bandages that
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Figure 7.4
Spinal immobilization.Courtesy: S.V. Mahadevan, MD.
become soaked with blood are not removed, but rather reinforced with further gauze. Tourniquets are only placed in cases of life-threatening limb hemorrhage that cannot be controlled with con- tinuous direct pressure, elevation, and banda- ging. If tourniquets are applied in the field, they should not be removed by EMS providers.
Pediatrics
Although EMS personnel at all levels are trained to evaluate, treat, and transport pediatric patients, many prehospital providers are uncomfortable when caring for acutely ill children. Such patients are relatively rare, and most cases evoke much more than the usual stress for those involved. In general, the most significant differences between acutely ill adult and pediatric patients are:
1. vital sign abnormalities indicating significant injury or illness may be delayed compared with adult patients;
2. the age-specific nature of normal pediatric vital signs may lead practitioners to misinterpret absolute vital signs;
3. procedures, including IV access and intubation, are technically more challenging in children; and
4. children may be unable to give adequate histories or cooperate with procedures such as immobilization, and may require
additional restraint for safe transport.
Recent data demonstrate that well-trained para- medics can deliver high-quality care to both adult and pediatric patients in nearly all arenas, but such care requires intensive education and regu- lar review of skills. One very important exception to this rule is that pediatric patients should rarely be intubated in the field, even in cases of respira- tory failure. Published data show that, in contrast with adults, morbidity and mortality are increased when prehospital care providers attempt to intub- ate apneic or hypoventilating pediatric patients.
In general, prehospital pediatric intubation should only be attempted when effective BVM ventila- tion cannot be achieved.