A polytrauma patient is a patient exhibiting damage or lesions to multiple organs and to different body systems with a more or less severe impairment of vital functions (Fig 1). In most traumatic conditions the main lesions affect the thorax, the abdomen and the central nervous system. In these patients, sedation or general anaesthesia is sometimes necessary in order to allow urgent diagnostic procedures, surgery or therapeutic manual manoeuvres.
Some of the available anaesthetics might not be appropriate because of their negative impact on an already impaired neurovegetative system. It is therefore important to be aware of the characteristics of these molecules and to define a procedural approach which must be rigorous and attentive in defining an adequate protocol for any type of emergency.
In polytrauma patients the secret for an appropriate anaesthesiologic approach lies in the ability of the Veterinary Surgeon to rapidly and thoroughly assess the trauma-induced conditions of the patient and to rapidly start with an appropriate and prompt stabilization procedure. This will allow the body to exploit the physiological compensatory mechanisms which are activated as a consequence of the traumatic event, as well as those which occur during anaesthesia. Unfortunately, it can sometimes happen that in spite of the clinical stabilization performed by the Veterinary Surgeon and the initial phase of recovery, the animal may start exhibiting symptoms attributable to ischaemic and reperfusion cellular lesions, which may result in systemic inflammatory response (SIRS) and in multiple organ failure.
Goal of the initial emergency procedures is to keep the animal alive, hence the need for a quick examination of the main lesions, a careful and appropriate triage and the implementation of elementary procedures such as the administration of oxygen and fluids and, when needed, ventilation. Once identified the main compromised organ systems and implemented the necessary emergency procedures, a more careful and in depth examination of the patient is possible in order to complete the clinical and diagnostic work-up and to establish a therapeutic plan.
CLINICAL EXAMINATION AND INITIAL STABILIZATION
The clinical examination of a polytrauma patient must include the taking of a brief clinical history, which must include:
- dynamics of the trauma, time elapsed and patient conditions prior to the event;
- previous or ongoing diseases (especially heart, renal, neurological and liver diseases);
- ongoing pharmacological treatments (antihypertensives, cardiokinetics, steroids, anticoagulants);
- previous allergies or adverse reactions to specific drugs.
The clinical examination of a traumatized patient must allow to rapidly assess the respiratory and cardiovascular function as well as the CNS status. The first thing to be done is to stabilize clinical conditions by restoring vital functions.
In conformity with the concepts developed by English language authors,the first approach to a polytraumatized patient must be based on the acronym A CRASH PLAN:
- A = Airways: assess the patency of the upper airways (nose, mouth, trachea) and the rib cage. Remove any possible material from the pharynx, larynx (Fig. 2) and/or trachea. Administer oxygen (100%) through a mask or a tracheal tube (if oral tracheal intubation is possible); if not possible, perform a tracheotomy (if the airway obstruction cannot be resolved rapidly).
- C = Cardiovascular: meaning a quick inspection of mucous tissues, of capillary refill time, temperature, peripheral pulse and cardiac impulse. Auscultation of the cardiac area, together with the assessment of the peripheral pulse (presence/absence), is fundamental. In hypothermic patients peripheral perfusion is decreased, due to vasoconstriction, consequently the peripheral pulse might not be easily identified. The disappearance of the femoral pulse is indicative of a systolic blood pressure inferior to 50-60 mmHg. If the patient is unconscious or the pulse absent, a severe hypotension or a cardiac arrest should be suspected; in these cases an immediate cardiopulmonary resuscitation is necessary.
- R = Respiratory: verify if the patient is breathing spontaneously; if not, intubate the patient and start intermittent positive pressure ventilation (IPPV) with oxygen. Assess respiratory functions such as amplitude, rhythm, etc.
- A = Abdomen: evaluation of wall integrity, auscultation, percussion.
- S = Spinal Cord: palpation, type of stance and gait, possible pain.
- H = Head: inspection and palpation of nose, lips, cranium, mandibles, teeth, eyes, ears.
- P = Pelvis: palpation of the pelvis, ischial tuberosity, hips, rectum, genitalia.
- L = Legs: gait, pain, tone, reflexes, joints, skin integrity.
- A = Arteries and Veins: peripheral pulse, jugular veins ectasia, presence of haematomas.
- N = Nervous System: consciousness, reflexes, examination of cranial nerves, evaluation of spinal cord integrity (Fig. 3).
In the presence of cardio-circulatory collapse an aggressive emergency fluid therapy is required; the insertion ofa large diameter venous catheter into a peripheral vein is therefore necessary and, when possible, of a central venous catheter into the jugular vein. Unfortunately, in collapsed animals with reduced venous return, vein detection inside the jugular groove is difficult; in such cases a skin incision with a scalpel blade is necessary to localize the vessel. Another possible alternative is the placement of an intraosseus vascular line (femur, humerus, tibia) using a needle with stylet (Fig.4).
Peripheral haemorrhages can be stopped with gauze swabs pressed against the bleeding area or, in the case of limb involvement, with the application of a sphygmomanometer cuff inflated to a pressure of 160-180 mmHg, maintained for 10-15 minutes with 2-3 minute intervals for a maximum of 2 hours. The cuff is not harmful to vascular structures and the ischaemic damage caused by an excessively tight tourniquet strap is therefore avoided.
Intra-abdominal haemorrhages can be contained via abdominal compression using a folded towel placed along the linea alba and kept in place with a compressive bandage: this operation reduces blood inflow to the entire abdominal cavity.
In order to restore part of the central blood volume, the hind limbs can be wrapped in semi elastic bandages, starting from the distal extremities and then bandaging up to the pelvis and the umbilical region. This technique prevents the pooling of venous blood in the caudal part of the abdomen and allows to maintain a normal blood pressure thanks to the compression exerted by the bandage, which reduces the diameter of both arterioles and venules.
Severe intra-thoracic haemorrhages must be treated surgically.
Once the general and the more specific clinical examinations have been completed, if necessary, or if time allows it, additional laboratory and instrumental tests specific for the type of trauma present are carried out in order to complete the assessment.
- Stabilization puts the patient in the best possible conditions to overcome both anaesthesia and surgery induced stress
- Administration of Oxygen
- No stabilization procedure can be started without oxygen administration (Fig.5). Polytrauma patients suffer from severe hypoxaemia, caused by such conditions as: direct damage to the thorax, hypermetabolic states caused by the release of catecholamines, cardiocirculatory collapse, etc.
- Restoration of Blood Volume
- Severe hypovolaemic hypotension can be corrected via rapid volume expansion with crystalloids (70-90 ml/kg/hr IV in the dog and 50-60 ml/kg/hr IV in the cat), colloids such as Dextran 70 or gelatines (20 ml/kg/hr IV), hypertonic solutions (2-4 ml/kg IV), blood, Oxyglobin®, etc.
- The most frequently used control parameter is the haematocrit, with a 15-20% range as the threshold used for decision taking. This relatively simplistic approach is used in view of the simplicity of the haematocrit measurement and of the strict correlation between oxygen transport and blood haemoglobin content. This simple approach must however be correlated with the overall status of the patient being treated. For example, the evaluation of other parameters, such as blood lactate and/or central venous saturation (a value < 70% might be indicative for the need of transfusion), may provide objective and specific information on the patient which may be then used by the anaesthesiologist to take the necessary clinical decisions.
- Blood transfusions should be considered only when the source of bleeding has been identified; it should not be forgotten that the ideal haematocrit for organ perfusion is of approximately 25-30%, and that in general hypoglobulinemia is acceptable with values up to 8 mg/dl in patients with acute hypovolemia and of up to 6 mg/dl in the presence of chronic hypovolemia.
- The improvement of blood circulation is fundamental to maintain a correct perfusion, even in the absence of hemorrhage. The improvement of clinical conditions is evidenced by a reduction in capillary refill time, restoration of mucous membrane colour, restoration of the peripheral pulse and the recovery of consciousness. In the presence of a severe state of shock, vasoactive and positive inotropic drugs should be used.
- During the induction of anaesthesia hypotension is probably the major cause for concern for the anesthesiologist, in view of the vasodilation caused by the negative inotropic action of anaesthetics. Goals of the anaesthesiologist are to keep the compensatory tachycardia under control, reduce the CRT and improve the mucous membrane colour, avoid an excessive depression of the CNS,increase blood pressure, control urine output in order to stabilize renal function and monitor the CVP in order to avoid an excessive fluid overload.
- Correction of Electrolyte and Acid-Base Balance
- The correction of electrolytes and of the acid/base balance should aim at making the following parameters at least acceptable: pH, pCO2, HCO3-, Na, Cl and K. In such cases an appropriate and targeted fluid therapy is desirable. Sometimes fluids, especially if used in large amounts, can severely alter NaCl values (Hypertonic saline solution) or can result in anexcessive overload of blood volume (colloids, whole blood). In case of excessive fluid administration it may be then necessary to correct the opposite disorder at the end of the anaesthesia.
- Control of Renal Function
- Renal funcion is often difficult to evaluateand one must therefore rely on the clinical history and on previous tests (blood and urine), without relying on just BUN and creatinine, which alone are not sufficient to determine the renal function. On the other hand, urinary output, specific gravity and electrolytes are extremely useful. In the presence of renal failure (RF) the common treatment consists in an adequate fluid therapy based on the existing differences between oliguric or anuric ARF and CRF. At times a reduced cardio-circulatory compliance may be the cause of ARF; in such cases the control of CVP is therefore mandatory.
- Recovery of Cardio-Circulatory and Respiratory Function to Improve Oxygen Transport Capacity.
- Perioperative monitoring is necessary in order to acquire clinically useful information necessary to take proper decisions and establish a prognosis for the patient. When the budget and the structure allow it, the following tests/measures should be made available for critical surgical patients: ECG, SpO2, EtCO2, central venous line, urinary output, temperature and, of course, clinical monitoring. When possible, monitoring should ideally be started during stabilization procedures, in order to allow the assessment of the efficacy of the treatments being implemented.
- When planning perioperative analgesia, veterinary surgeons should consider that improving patient comfort has a great benefit on cardio-respiratory function. In these patients, loco-regional anaesthesia is particularly effective and this technique can be performed during stabilization procedures in order to reduce waiting times for surgical intervention. Opiates and/or NSAIDS are used when clinically appropriate. Generally, trauma patients are good candidates for opiates, which are effective even if used at low dosages. Opiates have a negligible cardio-circulatory effect, but they have a relevant action on ventilation, causing ventilatory depression, especially when using short- and very short-acting opioids. For this reason in critical patients IPPV is necessary, together with the use of extremely rapid-onset opioids such as remifentanil.
- Evaluate if instrumental or laboratory tests can be rapidly performed in order to improve the anaesthetic protocol; these tests should include: liver/renal function, cardio-circulatory and respiratory function, identification of lesions to body systems and organs (thorax, abdomen, CNS).
- The following aspects should be evaluated: clinical history, clinical condition (ASA status), tests carried out prior to that moment.
- Indicate the main risk factors and establish when a risk becomes a danger.
WHEN TO WAIT AND STABILIZE
Frequently, the disorder present cannot be entirely resolved until the underlying causative pathology is treated; on such occasions optimization of the anaesthesiologic and surgical approach to the patient is fundamental, as it can reduce subsequent risks for the patient.
Patient stabilization is generally recommended in such traumatic conditions as:
- Urinary tract obstruction/rupture
- Diaphragmatic hernia
- Parenchymal rupture (spleen, liver, kidney)
- Hollow viscus rupture (bowel, oesophagus)
- Tracheal rupture
- Lung rupture/torsion
- Penetrating abdomino-thoracic injuries
- Polytrauma patient
In some cases immediate surgery is recommended, as some pathological conditions cannot be treatedwith stabilization only:
- Uncontrollable bleeding
- External bleeding
- Bleeding inside body cavities (thorax, abdomen)
- Visceral rupture
- Hollow viscera
- Parenchymas
- Penetrating trauma
Suggested readings
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- Bufalari A, Lachin A. Anestesia. Cane, gatto e animali non convenzionali. Edizione Elsevier/Masson, 2013.
- Campbell Vicky L. Anesthetic Protocols for Common Emergencies. Vet Clin Small Anim Pract. 2005;35:435-453.
- Corletto F. Anestesia nel cane e nel gatto. Poletto Editore, 2nd edition, 2010.
- Dyson Doris H, Mathews Karol A. Analgesiaand Chemical Restraint for the Emergent Patient. Vet Clin Small Anim Pract. 2005;35:481-515.
- Hall WL, Clarke KW, Trim CM. Veterinary Anaesthesia. W.B. Saunders, 10th edition, 2001.
- Haskins SC. Comparative cardiovascular and pulmonary effects of sedatives and anesthetic agents and anesthetic drug selection for the traumapatient. Journal of Veterinary Emergency and Critical Care, 2006;16(4):300-328.
- Muir WW. Hubbell JA, Bednarski RM, Skarda RT. Manuale di Anestesia Veterinaria. Elsevier Masson, 4th edition, 2008.
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- Viganò F. Medicina d’urgenza e terapia intensiva del cane e del gatto. Masson-Edizoni veterinarie, 2004.