Triaging the hit-by-car patient (Proceedings)

The role of the veterinary technician in traumatic emergencies is pivotal to the survival of the incoming patient. The physical exam must be quick, thorough, and concise. Utilization of all technical skills from careful visualization, palpation, and auscultation is of the utmost importance. The use of emergency equipment is also useful, but should not be a substitute for a proper physical exam. The following outline summarizes a systemic approach to the most common traumatic emergency, the hit-by-car (HBC).

The airway should always be evaluated immediately upon arrival of the HBC. As a rule of thumb, one must remove the most immediate threats of life first, the whole concept behind triage. If a patient presents breathing, note that this does not ensure a patent airway. Before any action is taken, visually watch both the respiratory effort and respiratory pattern. Are chest expansions adequate? Keep in mind that the patient just received a traumatic injury, rode in an automobile, and is now surrounded by strangers. The first evaluation of the respiratory system, therefore, although diagnostic, should be repeated after several minutes to several hours. Examples of common respiratory patterns secondary to trauma include abdominal breathing, paradoxical breathing, and shallow or poor chest expansions.

Note that these are patterns of respirations. They do not indicate a number. Tachypnea (elevation of the respiratory rate) is simply a number. It does not mark a pattern of respiration, or the effort of respiration. In traumatic injuries such as the HBC, most patients will be tachypnic from stress alone. Therefore, it is by the pattern of the respirations that can characterize the nature of the injury. For example, abdominal breathing can indicate a diaphragmatic hernia, severe pulmonary contusions, pneumonthorax, hemothorax, severe pain, or may indicate a metabolic abnormality such as acidosis secondary to poor perfusion. Paradoxical breathing can indicate a diaphragmatic hernia as well as blunt chest trauma, or can suggest a more severe diagnosis such as a cervical injury. Shallow or poor chest expansion can be a sign of shock, severe pneumonthorax or hemothorax, an obstructive airway, atelectasis, pain, or pulmonary parenchymal contusions. In any situation, if abnormal respiratory patterns are present, minimize the stress to the patient and administer oxygen therapy in the least stressful route. Evaluate other clinical signs of respiratory insufficiency such as mucus membrane color and pulse quality, to further assess the patient's immediate needs. Again, counting the number of respirations is important, but not as critical as characterizing the pattern. Recommended oxygen therapy is listed as follows: mask: 3-5 lpm, oxygen cage at least 40%, and intranasal catheter insufflation at 50-100ml/kg/min.

A quick, simple evaluation of the mucus membranes should also be a part of the check of the respiratory system. Note that in any traumatic injury, frequent evaluation of the membrane color is indicated. If a patient presents with normal, pink membranes but abnormal respiratory rate and pattern, the patient may not be hemodynamically stable. Repeat analysis of the membranes is essential. Note that pale membranes are an indication of a variety of incidences, from anemia to pain to hypoventilation. Again, note the respiratory pattern and respiratory effort to make a proper assessment of the patient's status in a timely fashion. Similarly, white mucus membranes, although abnormal, may not necessarily indicate a problem with the airway or respiratory system. White membranes may mean severe pain, hypothermia, shock, or ongoing blood loss. However, in addition to an abnormal respiratory pattern and rate/effort, the white membranes may suggest hypoventilation and the technician must administer oxygen in the least stressful route immediately. Cyanosis, or blue mucous membranes, indicates severe decompensation and respiratory shut down. Immediate action should be taken to reoxygenate the patient in the best effective manner.

Auscultation is the next step in evaluating the respiratory system. The patient should be sternal {if possible) and elimination of environmental noise for proper evaluation. If-possible, the patient should be refrained from panting or open mouth breathing, in order to auscult lung parenchyma and not referred airway noise. Frequent findings in the HBC patient auscultation include harsh lung sounds, decreased or absence of lung sounds, or guttural sounds in the thoracic area. Harsh lung sounds can be heard either ventrally or dorsally, either on inspiration or expiration, and may be isolated to the side of impact. Observe the respiratory pattern, respiratory effort, mucous membrane color, and utilize tools such as pulse oximetry or arterial blood gas analysis only as an extension to the physical exam findings. Administer oxygen if harsh lung sounds are present despite normal pulse oximeter values if the patient has any abnormal respiratory patterns or increased effort to ensure adequate oxygen exchange. Radiograph the thorax once the patient has been thoroughly evaluated and is not appear stressed. Thoracocentesis should not be attempted initially if there is no evidence of a pneumonthorax on radiographs and the patient has a normal respiratory rate and effort.

If the HBC patient presents with decreased lung sounds, oxygen should be administered despite pink membranes or normal effort. Decreased lung sounds may be auscultated ventral or dorsal, although the most common incidence is dorsal and does not have to be on the side of impact. Quickly examine the patient for rib fractures, flail chest, or evidence of subcutaneous emphysema. Thoracocentesis should be attempted after the patient has adequate supplemental oxygen delivery in the least stressful manner. The patient should be sternal for the procedure, with a clipped and prepped area where the decreased lung sounds were detected. Radiographs to confirm a pneumonthorax before a thoracocentesis are only warranted if the patient is stable or has a normal rate and effort to the respirations. (Refer to slides for thoracocentesis procedure). Note that the thoracocentesis should be attempted on both sides of the chest as air can pocket and may move freely. An unproductive chest tap in the presence of decreased lung sounds may indicate atelectasis or a diaphragmatic hernia. Note length of the thoracocentesis needle to ensure penetration of the thoracic cavity. Radiographs should be taken after the patient is stabilized. If the auscultation yields guttural sounds and the patient seems relatively stable, thoracocentesis is not recommended without radiographic examination. A diaphragmatic hernia may be present and thoracocentesis may lead to perforation of misplaced organs and resultant bacterial contamination of the chest cavity. Visually examine the chest area for detection of bruises, punctures, or flail chest should be incorporated into the triage.

After the respiratory system has been evaluated and the patient is receiving oxygen (if indicated), the next several minutes must be dedicated to the cardiovascular system. Pulse quality should be assessed immediately. Note if there are any differences between the femoral or pedal pulse quality. Keep in mind that if there is a difference between pedal and femoral pulses (the pedal usually being the weaker), this may be a sign of the patient's compensatory mechanism to shock. The canine, in particular, shunts the red blood cells to areas of stress or to non-vital organs in reaction to traumatic injury. The extremities may be cold to the touch and blood pressure poor. Obtain vascular access with the largest and shortest bore IV catheter (for rapid fluid administration) and obtain a baseline hemodynamic profile (PCV, TS, blood glucose, and BUN, and lactate).

Auscultation of the heart is the next step in triaging the HBC patient. Auscult the patient in sternal recumbency. Note that many murmurs or mitral regurgitation sounds are best noted while the patient is sternal as opposed to a lateral position. Note both the rhythm (pattern) and the heart sounds for distinguishing the presence of a murmur. Oftentimes, murmurs or cardiac a abnormalities are missed on the HBC due to tachycardia or elevated heart rate masking other sounds, or if the patient is shivering or shaking. Therefore, repeat auscultation when the patient is at rest, normothermic, or not in a stressful situation. An ECG should be performed to detect any abnormal complexes, which may arise from chest trauma, hypoxia, hypovolemia, or electrolytic abnormalities as a result of poor perfusion.

The most common abnormal ECG finding in the HBC are the presence of VPC's (ventricular precontractions), which usually do not surface until 24-72 hours post injury. The VPC's may be a result of myocardial trauma and are generally not treated unless greater than 40% or accompanied by tachycardia or pulse deficits. Note that if VPC's are present during triage or days after stabilization, hypoxia alone may be the cause. Arterial blood gas analysis can be useful in diagnosis. Treat the patient with oxygen therapy in the least stressful route and re-evaluate the electrical abnormality. If the oxygen therapy does not correct the VPC's and they-are sustained during triage despite fluid therapy (adjustment of hypovolemia), the cardiovasculature may be severely compromised either as a result of the trauma or from a pre-existing condition. Monitor blood pressure and pulse quality, and be cautious of fluid administration if the cardiac system remains abnormal. Central venous pressures can be monitored in such cases as a tool to aid the clinician in fluid therapy. The trends of the packed cell volume (PCV) and total solids (TS) must also be monitored in any traumatic injury, but in particular, with rapid fluid administration (see Fluid Therapy notes). Re-evaluate the ECG, blood pressure, and fluid administration particularly if pulmonary contusions (harsh lung sounds), or signs of head trauma, are present.

Fluid therapy for the HBC is recommended at 60-9Oml/kg for dogs and 30-40 ml/kg for cats, although each case should be evaluated individually and not treated as a mathematical formula. Re-evaluate blood pressure, pulse quality, respiratory rate and effort, PCV/TS, when one fourth of the calculated shock fluids have been administered. Again, if pulmonary contusions are present, or signs of head trauma are evident, be conservative with the fluid rate. Fluid additives should not be used during rapid fluid administration (IE: potassium chloride).

It is very important to watch the PCV/TS ratio in the HBC. Note that the PCV may be abnormally elevated in the dog that has sustained a traumatic injury due to the fact that the canine has the ability to sequester red blood cells and release them in periods of stress or physical exertion. In addition, a dehydrated patient can also have a falsely high PCV/TS ratio. Again, check the PCV/TS after thirty minutes or when one-fourth the shock fluids have been administered. Note that with large infusions of crystalloids, the heart rate should decrease. If the heart rate continues to increase or stays at a high number, re check the PCV/TS, evaluate the patient's pulse quality, and examine the patient for signs of pain, abdominal distension, and increased respiratory effort. Suspect an active bleed if the PCV/TS ratio is decreased in combination with decreased pulse quality and decreased blood pressure despite high crystalloid fluid administration. Note the total protein values, which may present normal then sustain a significant drop during fluid administration.

Abdominal centesis should be performed if an abdominal bleed is suspected, with a clipped and prepped area 2-4 cm caudal to the umbilicus. Consider a blood transfusion if the abdominal tap is positive and the PCV continues to fall dramatically or if blood pressure cannot be sustained. Placement of an abdominal wrap is advised if the bleeding is active and surgery cannot be performed immediately. Removal of the wrap must be done over the course of several hours (if the patient is not taken to surgery) or the clot created by the wrap may be dislodged or broken with reperfusion of the abdomen. Blood pressure should be monitored closely and may even be kept abnormally low to avoid dislodging a clot and exacerbating an acute bleed. The abdominal area should be examined for any bruising, punctures, or increased percussion. A urinary catheter should be placed and secured with a closed system if the patient is critical. The urine production should be monitored closely, particularly after large fluid administration. Suspect a ruptured bladder if the urine is not retained into the closed system or the bladder not visualized on radiographs. Ensure that the proper length of the catheter is into the tip of the bladder, and patency checked with sterile saline flush. If hematuria is present, the urinary catheter will need periodic saline flushes to avoid small clots plugging the end of the catheter, thus restricting urine flow.

Lastly, the neurological system must also be assessed within minutes of triaging the HBC patient. Note mentation: is the patient aware of the surroundings or hypersensitive to touch and sound? It is important to quickly examine the head for any external signs of trauma, including facial abrasions, mandibular or maxillary fractures. The ear and nasal cavities should also be evaluated for blood, which may be indicative of head trauma. Note the patient's pupillary light response, and look for signs of miosis, scleral hemorrhage, or hyphema. Be conservative with crystalloid fluid administration if any abnormal findings are present; colloid or hypertonic fluid therapy may be indicated to sustain blood pressure and pulse quality as opposed to large doses of crystalloids. Elevate the head to eliminate additional intracranial pressure, and avoid jugular venipuncture. In addition to cranial inspection, it is also important in the assessment of the neurological system to note neurological deficits sustained during a vehicular accident by examining the spinal cord. Check for motor and sensory output to the limbs and tail, keeping in mind that the absence of withdrawl or motor response should be re-evaluated after patient stabilization. Spinal cord swelling or severe shock (maldistribution of blood flow) can also affect the neurological exam but a prognosis should not be determined on the patient's first assessment. Hemodynamic stability must first be achieved for a neurological exam to be accurate, in combination with radiographic interpretation of the spinal cord and cranium.

The key to successful triage in the HBC is organization, teamwork, and remembering to RE-EVALUATE, RE-EVALUATE, RE-EVALUATE. Note that any patient can decompensate despite initial stability, and that pain can affect almost all hemodynamic findings. Be systemic in evaluating every HBC and concise with all treatments and procedures, and the HBC will benefit and mortality rate will decrease.