Approach to trauma special

Approach to trauma special Introduction A 6 month old, male entire Bedlington Terrier was presented to the R(D)SVS Emergency and Critical Care Service after falling from a 30 foot wall. The dog had been in the owner’s possession for since he was 8 weeks old and was up to date with vaccines, flea and worming treatment. The dog had no previous medical conditions. How do you conduct a primary survey of trauma patient? 1. Airways and breathing Respiratory rate and pattern – respiratory rate was increased at 60 breaths per minute with increased effort. Obstruction/ fluid in the mouth – no fluid or swelling within the mouth or nostril, some leaves noted in the mouth which were removed. No emphysema around trachea or thorax, no obvious crepitus on compression of thorax. Thoracic auscultation – dull respiratory noises heard dorsally and bilaterally, heart sounds were muffled. page 1 of 8 What is your conclusion from your primary airway survey? Currently, there are no signs of a perforated trachea or severe damage to thoracic wall or ribs. There was marked compromise in breathing. Dull lung sounds could indicate pleural space disease, in this case a pneumothorax is most likely as sounds are dorsal. Muffled cardiac sounds can also support pleural space disease although you could not rule out pericardial effusion at this stage. 2. Haemodynamic stability Heart rate – 200 beats per minute Pulse quality – weak femoral and metatarsal pulses Mucous membranes and capillary refill time – pale pink mucous membranes and a delayed capillary refill time of 4 seconds. Rectal temperature – 36.1 degrees centigrade. What is your conclusion from your primary haemodynamic stability survey? The patient was most likely in severe hypovolemic shock. This could be due to bleeding within the thorax, abdomen or severe fractures. Other causes for sudden hemodynamic instability could be obstructive shock such as pericardial effusion and a tension pneumothorax. 3. Neurological status Consciousness – severe obtundation, occasionally reacting to his environment Posture – the dog was collapsed, non-ambulatory, and was intermittently extending the forelimbs, although hind limbs appeared to have normal tone. Reflexes – withdrawals were present on all four limbs, there were normal patella reflexes present on both hind legs, there was a normal gag reflex, menace was present, and pupils were pin point and had severely delayed pupillary light reflex. What is your conclusion from your primary neurological status survey? The presence of obtundation and miosis indicated that there was a brainstem lesion. Normal patella reflexes indicated that the lower motor neuron pathways are intact. The extension of the forelimbs is ambiguous. Decerebrate rigidity would result in a brainstem lesion causing extension of all limbs and decreased level of consciousness stupor or coma. This patient was not experiencing this. page 2 of 8 Decerebellate rigidity caused by an acute cerebellar lesion results in opisthotonus thoracic limb extension and hip flexion, and normal consciousness. This animal was not opisthotonic. Schiff-Sherrington caused by lesions to the thoracolumbar spinal cord segments, results in extension of front legs and paralysis of the pelvic limbs. This patient was not paralysed in the hind limbs. The abnormal position did not fit into any of these categories but all the neurological signs together could indicate concussion and potential increase in intracranial pressure. This exam shows that the spinal cord is likely intact and the dog is not herniating his brain. How do you conduct a secondary survey? 1. Assessment of disability Abdominal palpation – moderate pain and no palpable bladder. Musculoskeletal examination – no crepitus or abnormalities on spine and hip palpation. Crepitus on right stifle manipulation. This was likely caused by a fracture. Skin – no lacerations seen on skin, patient turned over no lacerations or abrasions on the other side. What is your conclusion from your secondary survey? There was probably a fracture on the right hind limb that may need surgical intervention. It is important to check that there are pulses on this limb and the skin is not cold or an abnormal colour, indicating loss of perfusion which was not the case for this patient. The abdominal pain was concerning. This indicated that there could be damage to the abdominal organs and a non-palpable bladder could indicate rupture. What initial investigations would you like to do and what should you avoid? Blood work – PCV 40%, TS (total solids) 40g/l, glucose 15mmol/l, lactate 4.5mmol/l, electrolytes within normal limits, blood type DEA 1.1 NEG, blood smear – adequate platelet count ECG – showing sinus tachycardia Blood pressure – 90mmHg systolic SpO2 – 87% Thoracic FAST Ultrasound - no pericardial effusion or free fluid was found. However, an abnormal pattern was seen on M-mode suggestive of pneumothorax: page 3 of 8 Abdominal FAST Ultrasound – showed a moderate amount of free fluid around the liver and bladder. The bladder appears intact but small. Abdominal Tap – revealed serosanguinous fluid with a PCV of 50% and a TS of 30g/l Tests to avoid – Survey radiographs are important to assess rib fractures, the stifle injury and look for a diaphragmatic hernia. At this stage, however, the patient was too unstable to be manipulated on the radiography table. What do you make of these results and what treatments do you want to prioritise? Even though this patient’s PCV was 40%, the TS were abnormally low. In the initial stages of blood loss, the PCV and total solids drop simultaneously. However the spleen is able to contract releasing red blood cells into the vasculature which will temporarily raise the PCV. As the intravascular volume decreases, low protein fluid from the interstitium will move into the intravascular space in an attempt to maintain stroke volume and perfusion. This will dilute the proteins and drop the total solids. Eventually as the haemorrhage continues both PCV and TS will drop in tandem. As this dog had free fluid in the abdomen with a PCV of 50%, it is very likely that he had haemorrhage from either a splenic or liver laceration from blunt trauma. The bladder was small as this dog is concentrating his urine in order to help maintain perfusion. The glucose level was high because the patient was undergoing a huge degree of stress and the elevated lactate indicated poor oxygen delivery to the tissues, most likely due to hypovolemic shock. Worryingly this patient is also hypotensive indicating that the hypovolaemia could be severe. The dog was unable to maintain oxygen saturation showing that there were issues with gaseous exchange. The M-mode image shows a ‘bar code pattern’ which is typical of a pneumothorax. A pneumothorax would explain the drop in SpO2 and if it page 4 of 8 was building to a tension pneumothorax this would put pressure on the major vessels within the thorax which in turn leads to an additional obstructive shock, lowering blood pressure and perfusion. Treatment list 1. Intravenous access. – the patient was in a critical condition and had the potential to arrest at any point. Intravenous access was paramount. 2. Oxygen therapy – this dog was unable to saturate at room air so flow by oxygen must be given. 3. Pain relief – a full mu opioid agonist was used. NSAIDs was avoided due to hypo perfusion and paracetamol was avoided due to blunt trauma of the liver. 4. Thoracentesis – the pneumothorax in this animal was potentially the most life threatening condition at that point and had to be addressed immediately. If it is unclear whether a patient has a pneumothorax, thoracentesis can be a diagnostic tool as well as a therapeutic agent. 5. Intravenous fluid fluids – this dog is in hypovolemic shock and needs a replacement fluid to maintain perfusion. Blood products – the patient was losing whole blood; therefore, pack red blood cells and plasma or whole blood transfusion would be theoretically be the ideal replacement fluid. However, this is expensive and not always immediately available in veterinary patients, and transfusion reactions can occur. This patient may not need a blood product to make a full recovery. Colloids – these are large molecular synthetic substances that can maintain oncotic pressure. There has been concern in the human literature that these can cause acute kidney injuries and coagulopathies in patients with sepsis. Colloids are expensive but may be useful in a trauma case to maintain perfusion. Hypertonic crystalloids – fluids such as hypertonic saline has a higher osmolality than blood, therefore fluid from the extravascular space will move into the intravascular space, increasing, stroke volume and maintaining perfusion. In cases of head trauma with cerebral oedema hypertonic saline can reduce intracranial pressure. Hypertonic saline should never be administered in a dehydrated patient. Isotonic crystalloids – these fluids have the same osmolality as the blood, so as they initially increase stroke volume. However, they will quickly disperse into the extravascular space, so repeated boluses may be required. These products are cheap and readily available. Shock dose for a dog is 90ml/kg/hr; however, this method of bolusing is considered outdated. Too much crystalloids that are not needed can damage the endothelial lining of the blood vessels and cause leakage. Starting with 10-20ml/kg boluses over 15 minutes and re-evaluating the situation is the safest way of administering these products. In human practice, people who are haemorrhaging are often hypotensively resuscitated as an attempt to allow clot development and prevent further page 5 of 8 haemorrhage. This can be difficult in veterinary medicine to achieve and could be dangerous if not monitored correctly. However, not over loading patients with fluids is important. In this case as we had a pneumothorax, it likely that pulmonary contusions are present. Overzealous fluid therapy could cause further damage to the lungs. On the other hand , this patient is showing signs of concussion. If head trauma is suspected it is paramount to maintain perfusion to the brain and hypotensive resuscitation is contraindicated. 6. Managing the head trauma – this patient was demonstrating neurological signs and the clinician must be concerned about raised intracranial pressure. It is important to provide oxygen, have the patient’s head raised on a board at a 30 degree angle, no jugular samples should be taken and pressure around the neck avoided. Drugs that increase intracranial pressure such as ketamine should also not be used. In humans, it can be beneficial to keep a patient below normal body temperature to reduce the rate of metabolism. In veterinary patients this may be difficult to achieve and having a patient cold could be harmful. It is paramount in head trauma to maintain adequate blood pressure to the brain, so volume resuscitating a patient is very important. If neurological signs progress and the patient develops hypertension and bradycardia (Cushing’s reflex) then a hyperosmotic agent may need to be considered. Mannitol can be used to reduce cerebral oedema; however ,it must be given in a patient that is normovoleamic. Hypertonic saline could also be used but this could exacerbate pulmonary contusions. If there is intracranial haemorrhage then both these agents could exacerbate bleeding and make oedema worse. Treatment and outcome An intravenous catheter was placed, the patient was placed on a hard board angled at 30 degrees and flow by oxygen was initiated. Methadone was administered at 0.2mg/kg initially. Thoracentesis was performed and 500ml of air was drained form the right side. This greatly improved the respiratory rate and effort, the SpO2 raised to 98% and the blood pressure also increased to 100mmHg. To maintain the blood pressure the patient received three 10ml/kg boluses of isotonic crystalloid fluids. It was decided after this to give two 2ml/kg boluses of colloids instead of continuing with the crystalloids to help prevent damage to the lungs. The blood pressure increased to 120mmHg, the pulse quality improved and capillary refill time normalised. However he was still tachycardic at 150 beats per minute so a fentanyl CRI was started at 5 mcg/kg/hr. This reduced the heart rate to 100 beats per minute. During this time the miosis of the pupils worsened and as he was volume resuscitated it was decided to give a 0.5g/kg bolus of mannitol. The neurological signs did not improve immediately; however, there was no further deterioration. The dog was actively warmed to 37 degrees centigrade then active warming was stopped. page 6 of 8 When the patient was more stable radiographs and a CT scan were performed. These revealed no diaphragmatic hernia and no spinal, skull or rib fractures. He had marked, diffuse alveolar pattern in the right and left lung lobes indicating pulmonary contusions. There was a moderate amount of free fluid pooling around the liver lobes and the bladder was intact. There was a complete oblique fracture on the distal right femur which was classified as a Salter Harris type 2 fracture. Since this patient remained non-ambulatory, a urinary catheter was placed and fluid therapy was calculated to provided maintenance support and match urinary output. 1. Create a monitoring plan for this patient 1. Continuous ECG for 12 hours to check if any arrhythmias develop. Mucous membranes, pulse quality, blood pressure and temperature was monitored q4 hours to assess perfusion. The dog remained haemodynamically stable overnight. 2. Respiratory rate was monitored every two hours and SpO2 was checked q4 hours. The oxygen saturation stayed at 98% and the respiratory pattern was normal. The dog was weaned off oxygen overnight. 3. Modified Glasgow Coma Scale was measured every four hours to assess neurological deterioration. Through the night the MGCS improved to almost a normal score and after 48 hours the miosis had resolved and the PLRs were normal. 4. Urinary output and urine specific gravity monitored q4 hours. USG was initially 1.037 indicating that the patient was conserving fluids to compensate for the hypovolaemia. A rate of 3ml/kg/hr of fluids was given and urine output stayed stable at 2.5-3ml/kg/hr. 5. Pain score q4 hours. This patient remained comfortable on 5mcg/kg/hr of fentanyl through the night and during the day was reduced to 2mcg/kg/hr. 6. PCV, TS lactate glucose and electrolytes monitored q6 hours. Electrolytes remained within normal limits, glucose and lactate improved to 6mmol/l and 0.8mmol/l respectively within 6 hours. The PCV initially dropped to 28% but by the morning has risen to 32%, indicating reabsorption of blood from the abdomen. 7. Repeating rapid thoracic and abdominal scans q6 hours. The free fluid started to resolve over the night. Within 24 hours, the patient was ambulating and eating so the urinary catheter was removed. It can take 48-72 hours for pulmonary contusions to worsen so he was rested and monitored for 72 hours before he had a surgery to fix his fracture which was secured with two crossed K wires. page 7 of 8 The patient was discharged from the hospital four days later and made a good recovery. Discussion Poly trauma is a very challenging situation that general practitioners will be faced with. Focusing on damage to the major body systems and identifying and prioritising dealing with the most life threatening situation first is paramount. page 8 of 8