President, Veterinary Surgery, Emergency, and Critical Care Consulting, Bogart, GA

Surgeon and Critical Care Specialist, All Pets Emergency and Referral Center, Alpharetta, GA

Clinical Associate Professor, Institute of Critical Care Medicine, Palm Springs, CA

Firefighter and EMT-2, Oconee County Fire Department, Watkinsville, GA

EMT- Paramedic Instructor, Lanier Technical College, Oakwood, Ga

crowehome@aol.com 706-296-7020 www.dtimcrowe.com

INTRODUCTION - The purpose of this address is to provide information that will help the practicing veterinarian and veterinary technicians care of the emergency and critical small animal patient. This will include an overview of some of the general concepts; basic physiology and anatomy involving oxygen delivery; recommendations concerning readiness for the patient care; and care and assessment guidelines for care of the critical patient. Throughout the address patients will be presented that will exemplify the critical care they needed to emphasize key points. The references will provide further information on each specific area if the reader chooses. The first 8 are particularly informative with photographs and case examples (1-8).

GENERAL CONCEPTS - Because of the life-and-death conditions involved with critical patients each decision made and the care subsequently provided is consequential (1) Even what is told to an owner with their initial phone call inquiring about a potential visit and what they should do at home before coming can make critical difference in what occurs. An example is a dog "Annie" with small amount of fluid dripping from her spay incision and a small swelling noted there. The technician answering the phone suggests Anne be seen and makes an appointment for that afternoon. Another similar scenario is called in. This dog "Alice" also has fluid dripping from a spay incision. Another technician taking the call suggested that the owner wrap a towel around Alice's body and transport her carefully right away and warned the owner not to let the dog jump out of the car. On arrival at the hospital Annie was allowed to jump out of the car and dumped her intestines on the surface of the parking lot. She attempted to run and dragged the intestines into dirt and gravel and tore it open. She was admitted for immediate surgery. Alice on the other hand presented with a large towel around her "middle" and was carefully moved into the triage area. On removing the towel omentum was found hanging out. Saline was added to the drying out omentum and the dog was also admitted for surgery.

Another example is a patient "Copper", an Irish Setter who was choking from a airway foreign body and the owner called in a panic. The veterinarian instructed the caller on how to remove the ball from Copper's throat. The dog passed out and with a sweeping motion the ball was removed by the owner. The owner did a minute of rescue breathing before Copper started breathing OK on his own. The owner brought Copper in to get checked out. Other than for a little unsteady gait Copper was found to be OK. He made a complete recovery.

Although many critical patients will require much time and expense to provide the care necessary to resolve their medical or surgical problems, others will not, particularly if the care needed if done early in the course of the illness or post-injury as exemplified by two of the three patients described above. Although both Annie and Alice recovered completely the cost for Annie was greater than 3 times that needed for Alice as she required a bowel resection and extensive irrigation to clean off mesentery and had to stay in the hospital on intravenous fluids and antibiotics for several days. Alice required only a nigh in the hospital and the problem was not nearly as potentially life-threatening. The owner of Annie was also not at all happy when she found out the difference in the care that was required between the two dogs as the two owners "compared notes" while visiting in the lobby. She said the hospital "may hear" about that further from her attorney as her dog Annie had to undergo much more than Alice; all because she was not told about the risks involved on the phone as Alice's owner was before transport. Hence the need for appropriate and timely care, even from the time of the initial call. This has been published and recognized as one of the keys to successful emergency care in veterinary medicine. (1-3)

Critical care and emergency care also involves ongoing assessment and monitoring, and the execution of corrective and supportive procedures and activities that also been previously published (2). These are very briefly noted as follows:

1. Airway and ventilatory assessment, and support; oxygen supplementation. (3,4,8)

2. Cardiovascular assessment involving blood flow and oxygen delivery and support. (2,6)

3. Neurologic assessment and necessary care as needed including analgesia, anesthesia, anxiolysis. (3)

4. Gastrointestinal system support including early enteral nutrition. (1,2,7)

5. Fluid and electrolyte assessment and support. (1,2,7)

6. Specific organ function assessment and support (liver, pancreas, kidney) (1,2,7)

7. Musculoskeletal and dermal assessment and support. (1,2,7)

8. Emotional support for the patient, owner, owners family. (1,2)

9. Emotional support that also extends to those providing the care. (1)

OXYGEN DELIVERY -. Multiple factors affect oxygen delivery to the cells.(4,6,9) These include:

1. Amount of oxygen provided to the patient to breathe (FiO2)

2. Effectiveness of oxygen delivery to the alveoli (PAO2);

3. Effectiveness of oxygen exchange at the capillary (PaO2);

4. The presence of sufficient hemoglobin to carry the oxygen and release it at the tissue level (Hb);

5. Global cardiac output and adequate flow to the tissues (CO);

Cardiac output is determined by circulating blood volume, cardiac muscle strength, vascular tone and heart rate.(9) The best way to assess tissue blood flow and effective cardiac output getting to the peripheral tissues, from a practical point of view, is to listen to Doppler blood flow on a beat to beat basis. (1,2,10-12) The Parks Medical Electronics, Inc., Ultrasonic Doppler Blood Flow Detector Model 811-B (19460 S.W. Shaw, Aloha, OR 97007 1-800-547-6427) and the accompanying pediatric flat probe are approximately $750.00 and are very good for the monitoring of flows in both dogs and cats. Blood pressure can also be monitored by use of an appropriately sized blood pressure cuff (40% the circumference of the limb) placed proximal to the placement of the flow probe. As has been documented capillary blood flow is dependent on blood pressure differential between the arterial and venous beds.(9) But blood flow in itself, as continuously monitored by auditory assessment of flow sounds, in my opinion, is the most important to monitor and can easily be done by listening to flow characteristics with the probe placed over the palmar or plantar arterial arch. A "full sound" even in the face of a lower than normal systolic pressure indicates "adequate arterial blood flow" whereas a "short weak sound" heard even in the face of a high or normal systolic pressure indicates inadequate arterial blood flow. This can be explained by increased vascular resistance caused by arteriolar vasoconstriction leading to decreased flow.(9) The Doppler unit can also be taped to an esophageal stethoscope and used to monitor aortic blood flows in low flow and unconscious states with significant accuracy.(10) It can also be used to effectively monitor blood flow cranially during CPCR using the probe on the eye.(11,12)

Success in emergency and critical patient care means patient care survival with as minimal long term morbidity as possible. This requires "High Priority Resuscitation" or resuscitation procedures that can not wait and they MUST be addressed immediately upon arrival and continued to be addressed throughout the course of care. They are those procedures aimed at maximizing oxygen delivery and are based on both basic anatomy and physiology. The treatment must be appropriate and must be provided in a timely manner (1,2). Research has shown that if cellular hypoxia to the gastrointestinal tract in dogs continues beyond an hour even though global resuscitation from blood loss appears adequate death from organ dysfunction and sepsis from gastrointestinal bacterial translocation and endotoxin absorption across the gut wall will likely occur a day to several days following the insult.(13,14) The patient might recover initially but will then suffer or die later from gastrointestinal, renal, hepatic, pancreatic malfunction due to apoptosis.(13,14) Therefore successful critical care again reiterated requires timely and accurate patient assessment and resuscitation in proper sequence according to physiologic priorities (airway, beathing, circulation, disability, and everything else) and then continued assessment and supportive care as required (supplemental oxygen, respiratory support, nutritional support, fluid and electrolyte support; physical therapy; and skin and catheter care, etc.).(1-8) The first two of these components occur simultaneously in the seriously injured or ill patient and are included in the decision making that must performed accurately and in as short of times as possible. One thing that can not be bought is TIME. Therefore the decisions made not only have to be accurate but also the resuscitation care must be completed with expedience. Hence the emergency and critical care team must always be in a state of readiness.(1,2)

READINESS - The goal of initial and subsequent care of the critical patient is to determine the critical life-and-death disorders present; resuscitate, and do what ever that require to improve the delivery of oxygen (O2) and nutrients to the tissues; to arrest the cause of the problem or problems identified (i.e., opening the airway, controlling hemorrhage, etc.); correcting anatomical defects or malfunctions caused by the injury or disease before their consequences impart further serious life-threatening complications; and provide continued supportive care required to allow the reestablishment of homeostasis. To provide this in a timely and most efficient fashion takes effort on the parts of the whole veterinary medical team. A state of readiness must be maintained. This involves having the appropriate equipment, supplies and drugs available and assembled in a organized fashion (1,2) From training in both veterinary and human critical care and rotations at several university and private veterinary and human centers including the Shock-Trauma Center in Baltimore, the following recommendations are made regarding the delivery of critical care:

1. Have at least two trained support staff and one veterinarian on duty at all times (24-7-365).

2. Have a "Ready" triage-resuscitation area set up at all times using the "open concept".

3. Have an area in the hospital that is designated for the care of critical patients (Critical Care Unit).

4. Have a "24-hour lab" with the ability to do arterial and venous blood gases and electrolytes.

5. Have "24 hour" imaging capabilities that allow radiographic and ultrasound assessment.

6. Have an operating room in readiness to allow emergency rapid deep cavity interventions, etc.

7. Have pharmacy capabilities that includes most resuscitation and support drugs and blood products.

8. Use check-off and flow resuscitation and critical care flow sheets for recording and monitoring.

9. Use progress notes and SOAP patients, at least once daily, and communication sheets.

10. Use printed protocols and guidelines for standard operating procedures/guidelines (SOPs/SOG's).

11. Have a referral - backup system in place and use it when cases become overwhelming. Ask for help!

12. Continue training and knowledge in basic, advanced and supportive care and continue to up-grade.

13. Have a logistics recording system functioning that recover all costs and record all charges.

14. Have a logistics system functioning that will prevent the exhausting of resources and supplies needed.

15. Provide owner emotional support and always show caring and concern for their critical pet.

GUIDELINES - The following general guidelines are divided into assessment, resuscitation, and general critical care support.(1-7) Appropriate treatment of the critical patient can be instituted only if the patient has been evaluated appropriately. From the time the pet is presented to the hospital to the time it is discharged primary and secondary exam surveys should be performed frequently. An example of a guideline / protocol for the care of an emergency is presented in table 1: Protocol for care of blunt and penetrating trauma.

Assessment - In the triage setting the survey should be quickly performed (1,3). It always is done the same. At other times it is performed in a slower paced setting and more thoroughly, such as after admission into the CCU (Critical Care Unit) If a life-threatening problem is recognized as the primary survey is done resuscitative procedures are immediately done without progressing further through the survey. Triage and multiple daily surveys examine breathing effort and respiratory pattern, abnormal body or limb posture, the presence of blood or other materials in or around the patient, and any other gross abnormalities. Level of consciousness (LOC) is assessed along with airway, breathing, and circulation effectiveness. If the animal is unconscious the head and neck should be extended to help provide a clear airway, assuming there are no concerns for a cervical spinal injury. The airway (A) (nose, mouth, pharynx, and trachea) is checked for patency by looking, listening, and feeling. Recall from basic applied anatomy and physiology that airway resistance is proportional to the radius of the airway opening to the fourth power, according to the law of Poiseuille (Q [flow] = P1-P2r4 / 8nl.(8) Therefore with unconscious patients with the tongue causing a partial obstruction to the rima glottis the head and neck should be immediately extended and the tongue pulled rostrally. For patients with wheezes a bronchodilator such as a beta 2 agonist should be administered as an aerosol using a micronebulizer attached to a oxygen stream.(2,4) If necessary bag-valve mask ventilation can be used to provide forced assisted ventilation support. This easy to apply technique, in the author's experience, has been on of the most life-saving procedures he has done for the difficult breathing patient.(3-5) Appropriate precautions always should be taken when examining a patient’s oral cavity and oropharynx to ensure no one is bitten. Fingers should never be placed into the mouth of an agonal patient as this can lead to a serious injury.

The presence of increased respiratory effort, paradoxical chest wall movement, abdominal wall movement with respiration, nasal flare, open mouth, extended head and neck, abducted elbows, and cyanosis are all indicators of respiratory distress which require immediate treatment. Breathing is assessed by watching chest wall motion as well as listening to tracheal and lung sounds bilaterally. It is important to auscult lung sounds bilaterally since the animal may have a significant unilateral pneumothorax or hemothorax. Lung sounds always should be ausculted prior to listening to heart tones since the ear is much less discerning of softer sounds once it has adjusted to louder sounds.

Circulation is assessed by checking mucous membrane color and capillary refill time, and ausculting for heart tones at the same time as palpating central (femoral) pulses.(3) Finally assessment and palpation and examination of the abdomen, flank, pelvis, spine and limbs is carried out during the primary exam surveys. In the unconscious patient blood flow assessment can be enhanced by the placement of a Doppler flow probe on the patient's eye and the pulsitile flow assessed. Placement of a Doppler flow probe on the palmar arterial arch is done in animals that are conscious and blood flow and blood pressure via an appropriately sized sphygmomanometer. Flow should be easily detected and strong and arterial BP should be targeted at 100-120/70-90. The venous (blood volume or capacitance) side of the circulation is assessed by clipping the jugular vein area and assessing how it fills when the vein is digitally obstructed.(3,6,7) The jugular vein should fill within 3-5 seconds and should fill well. Prolonged filling times >10 seconds definitely indicates poor venous volume and flow requiring volume or pressure support. A significantly filled vein indicates either a tension pneumothorax. pericardial tamponade or other cause for venous return to the right atrium. In the trauma patient volume loss can make it difficult to detect the presence of venous return impairment.(6,7)

Assessment of the critical patient also involves many other modalities and are recommended: This includes non-invasive blood pressure monitoring that may progress to direct arterial pressure monitoring with the placement of an arterial catheter; central venous pressure monitoring; a CBC with examination of a blood smear and differential; a serum chemistry profile, coagulation panel, arterial and venous blood gases, lactic acid, urine output and urinalysis, thoracic and abdominal radiographs and ultrasound assessment; and other techniques. Assessment and monitoring in all critical patients should also include daily fluid, carbohydrate, protein, and fat intake.(12) In the ventilated patient continuous capnography and SpO2 are considered mandatory.(6,7) Ventilatory parameters (ventilatory rate, peak inspiratory pressures, tidal volume, positive end-expiratory pressure, percent inspiratory oxygen) should also be monitored.

Resuscitation - If major abnormalities are noted treatment is instituted immediately. For example, if the animal is found unconscious and not breathing the airway is assessed, the head and neck extended, the mouth closed over the extended tongue and mouth to nose and mouth rescue breathing should be started. Use of a BVM (bag-valve-mask) attached to reservoir and oxygen delivered at 10-15 liters per minute is ideal and if already assembled and ready should be instituted rather than the mouth to nose technique.(3-5) Endotracheal intubation should be followed as soon as possible and ventilation with the use of a bag-valve reservoir-oxygen system should be started.(8) (If the unconscious patient cannot be intubated due to severe facial or laryngeal trauma an emergent tracheotomy should be performed immediately. An emergent tracheotomy is performed when the patient is dying due to the lack of a patent airway. The procedure, which is performed without clipping fur or performing a surgical prep takes less than 60 seconds. In the awake patient with severe upper airway compromise a tracheotomy can be performed under local anesthetic. An awake tracheotomy can also be used in the conscious or stuporous patient that requires positive pressure ventilation. In the hemodynamically unstable patient this will avoid the need for general anesthesia. The respiratory rate should be recorded and the breathing pattern should be closely observed.

Thoracentesis should be performed bilaterally in any patient in whom there is concern that the patient has a pneumothorax or a hemothorax.(8) This should be done prior to taking chest radiographs since positioning the patient for radiographs may worsen respiration and may cause the animal to decompensate. Placement of a chest tube is indicated if negative pressure is never achieved during thoracentesis or thoracentesis is required more than twice within 2 to 4 hours. Chest tubes should be placed under sedation and local anesthesia rather than general anesthesia unless control of the patient’s ventilation is required.

In the absence of blood gases and the ability to assess SpO2 which is very common, if the animal appears to have any breathing difficulty or shock supplemental oxygen should be provided from the time of admission. This can be administered by placing tubing from an O2 tank or anesthetic machine in front of the patient’s nose and mouth and running high flow rates (3 to 15 liters/min) via small tubing. Smaller patients can be placed in clear plastic bags. The O2 tubing is placed through a small hole in the front of the bag thus creating an O2 tent. The back end of the bag is left open and the examination can be completed with the patient in the bag. Supplemental flow-by O2 should be followed by delivery of O2 by non-re-breathing face mask, oxygen hood, CROWE oxygen collar, nasal, nasopharyngeal, nasotracheal, or transtracheal catheters or the use of either adult, pediatric or infant bilateral nasal cannula (nasal prongs).(4) The latter can be placed quickly with a section of tape placed on the device to form a nose-band then the apparatus is stapled to the patient's face and the loop slipped and tightened behind the patient's head.(4)

In the severely traumatized patient it should be assumed that fractures are present until proven otherwise and ideally the patient should be restrained to prevent further injury. Restraint should be minimized if the patient is likely to injure himself further by struggling, if restraint will compromise the airway, breathing or circulation, or if restraint will cause the patient more pain. If there is concern that the patient may injure itself further if it is not restrained it may be appropriate to consider sedating the animal. Tape can be placed over the rostral aspect of the patient at the level of the wing of the atlas, over the cranial thorax at the level of the scapula and caudally over the wing of the ilium.(1,3) Backboards made from Plexiglas are useful because not only are they sturdy, but the animal can be visualized on all sides, and radiographs can be taken without having to remove the animal from the board. An example is Whisky White who was hit by an SUV.(7) He sustained a luxation of L2-L3 and became significantly paraparetic. He was placed on a board almost immediately. He was treated for shock which required oxygen supplementation, placement of a red rubber feeding tube into the right jugular vein and fluid administration with Oxyglobin (Biopure, Cambridge, MA), hypertonic saline, hetastarch and plasma. He was intubated with ketamine diazepam induction and placed on a ventilator. The spine was decompressed and stabilized with two bone plates. Hyperbaric oxygen was used postoperatively for several days and then was discharged. He returned 9 days later with acute respiratory failure that was determined to be a diaphragmatic hernia. Near cardiac arrest occurred requiring rapid open chest resuscitation. He able to be discharged several days later after the hernia was repaired.

Many severely traumatized patients present with pulmonary injury that worsens rapidly during the early phase of resuscitation (5,7). Patients with severe pulmonary contusions or ventilatory failure due to muscle weakness from severe shock may not respond to supplemental O2. A decision should be made to intubate and artificially ventilate the patient if cyanosis or respiratory distress do not resolve with the provision of supplemental O2, or if respiratory effort is worsening despite provision of supplemental O2 (8). If arterial blood gases are available positive pressure ventilation should be instituted if the arterial oxygen tension (PaO2) is less than 60 mm Hg with supplemental O2, or the arterial carbon dioxide tension (PaCO2) is greater than 55 mm Hg. If the clinician feels confident that a pulse oximeter sensor is providing accurate readings, and oxygen saturation is less than 90 to 92% on supplemental oxygen, and there is evidence of respiratory distress, artificial ventilation is indicated.

Rapid control of the airway should be the goal since a prolonged induction may be fatal to the patient.(8) Drugs should be chosen with care as these patients are usually hemodynamically unstable and many anesthetic agents depress cardiac function and cause hypotension. Ketamine hydrochloride (5 to 10 mg/kg IV) and diazepam (0.1 to 0.5 mg/kg IV) are ideal for rapid induction and then continued tube acceptance with the use of pentobarbital 1 mg/kg/hr or a combination of narcotics (oxymorphone hydrochloride h [0.05 to 0.1 mg/kg IV], or fentanyl citrate i[0.002 mg/kg IV; 30 to 60 mcg/kg/hr infusion]), in combination with diazepam (0.2 to 0.5 mg/kg IV), and neuromuscular blockers (atracurium besylate [0.25 mg/kg IV; 0.1 mg/kg redose or 180 to 480 mcg/kg/hr infusion]), provides the safest means of maintaining trauma patients under anesthesia during positive pressure ventilatory support. All anesthetic drugs should be titrated to effect since patients in shock are much less tolerant of anesthetic agents than healthy animals and these doses are only intended as guidelines. In general it is recommended to start at 25 to 50 percent of the dose used in a healthy animal.

The priorities with positive pressure ventilation are to correct hypoxemia by maintaining PaO2 greater than 60 mm Hg and to maintain PaCO2 in the range of 35 to 45 mm Hg (5-8) Initially, positive pressure ventilation can be instituted using a manually operated AMBU bag; however, since most of these patients require multiple hours of ventilation therapy while the injured lung tissue heals, mechanical ventilation is preferred. Peak inspiratory pressures should be kept as low as possible (below 20 cm water) to avoid iatrogenic damage to injured lung tissue. The use of positive end expiratory pressure will help decrease inspiratory pressures in the pulmonary injured patient with a high ventilation-perfusion mismatch. Therefore, if peak inspiratory pressures above 20 cm water are required to maintain adequate O2 levels, positive end expiratory pressure (PEEP) should be instituted. Positive end expiratory pressure can be instituted when using an AMBU bag if the bag is fitted with a valve that regulates expiratory pressure. Positive end expiratory pressure ideally should remain below 10 cm water; however, it should be kept in mind that even 3 to 5 cm water may lower cardiac output by decreasing venous return to the heart. Therefore, it is very important to ensure adequate intravascular volume is maintained, and that BP and urine output are monitored closely. If cardiac contractility is depressed secondary to the trauma or sepsis positive inotropes may be required (dopamine and dobutamine beginning at 5 mcg/kg/min) along with continuous direct or indirect blood pressure and continuous electrocardiogram monitoring.(6)

Tidal volumes of approximately 10 to 15 ml/kg should be used and the ventilatory rate should be adjusted to maintain the PaCO2 in the desired range. The trauma patient has increased oxygen demands and PaO2 should ideally be maintained in a high normal range (80 to 100 mm Hg minimum). Oxygen toxicity may occur within 6 hours of breathing inspired concentrations of 100 percent O2 and levels should be reduced to below 60 percent as soon as it is feasible. The decision to provide artificial ventilatory support should not be undertaken lightly. These patients require intensive monitoring and 24 hour care. If a pneumothorax was present prior to starting ventilation therapy then unilateral or bilateral chest tubes will be required rapidly since positive pressure ventilation will worsen the air leak.(8) Trauma patients on ventilators may develop pneumothoraces because the added pressure from the ventilation can rupture injured lung tissue. The lungs should be ausculted bilaterally at least hourly. Any decrease in airway sounds during auscultation of the thorax, any unexplained decrease in PaO2, or any increase in PaCO2, may be an indicator of a pneumothorax and thoracentesis should be performed. If blood gases are not available pulse oximetry and capnometry using an end-tidal CO2 monitor will help evaluate the effectiveness of ventilator therapy. End tidal CO2 levels should be from 30-45 mmHg and the wave form should be characteristic of a good flow and exchange of CO2 at the alveolar level.

Assuming no intrathoracic pathology, CVP is a reflection of preload or venous volume returning to the heart (2). Since adequate cardiac output depends in part on preload, CVP should be monitored as a guide to fluid therapy. Although normal CVP is reported to vary from between 0 and 10 cm of water, the goal during resuscitation should be to maintain the CVP between approximately 5 to 8 cm water. The volume and rate of fluid administration will depend on the patient’s hemodynamic parameters. In general, hemodynamic parameters should be returned to normal as fast as possible, provided ongoing hemorrhage is NOT suspected. In this case incremental boluses will be more appropriate with a target of quality flow but systolic arterial blood pressure kept under 80 mmHg for an hour. The exception ton this may be profound head injury with cerebral edema suspected.(6) If the patient is tachycardic and assessed to be hypovolemic, fluids should be given until the heart rate returns to close to normal. If pain is suspected as being the cause of the tachycardia it is recommended to be appropriately treated.

Guidelines for Fluid Administration - If the BP is low or not detectable, fluids should be administered as fast as possible to return BP to at least detectable (if ongoing hemorrhage at all possible) or to normal as soon as possible (if not). In my opinion based on clinical experience if the patient is in shock because of hemorrhage large volumes of crystalloids should be avoided since interstitial edema may result. If the patient is hypotensive or normotensive and tachycardic, a bolus of a crystalloid of 30 ml/kg is followed by reevaluation of the patient’s heart rate and BP. If the hemodynamic parameters improve and then deteriorate, or if they have not improved, a synthetic colloid is administered in slow intravenous boluses of 5 ml/kg up and give to a total of 20 ml/kg and the crystalloid administration rate is decreased to 3 ml/kg/hr. If the patient stabilizes after the bolus of crystalloid then the crystalloids are continued at maintenance rates. If the patient has no detectable BP or if the BP is below 50 mm Hg systolic, 6% synthetic colloids [3 ml/kg] mixed with 23.5% hypertonic saline (1 ml/kg) and this colloid mixture should be administered at 1-2 ml/kg at a time and each of these boluses are given every 3-5 minutes until 5-6 ml/kg of the mixture total is given. If blood is available it can be substituted for the synthetic colloid or ideally with an oxygen carrying colloid such as Oxyglobin, a hemoglobin based oxygen carrier (HBOC). In my experience HBOCs are also beneficial in helping sustain oxygen delivery in situations were blood loss has not been significant yet perfusion has been a problem such as in gastric dilation-volvulus and small intestinal perforation-obstruction.

The packed cell volume and total plasma protein should be reevaluated after the first 30 to 60 minutes in any patient who is not responding to fluid resuscitation or if the packed cell volume is less than 20 percent or has dropped by more than 50 percent of baseline. In these red blood cell transfusion is also recommended. Since these patients also will be predisposed to a dilutional coagulopathy FFP should be concurrently administered. If fresh whole blood is available it is the blood product of choice in trauma patients.

Further important information concerning fluid support in hypovolemia are briefly listed:

1. E. coli septic shock in dogs causes significant vasodilation that leads to significantly decreased arterial pressure, cardiac index, mesenteric blood flow, and systemic and mesenteric oxygen delivery and increased arterial, venous and portal lactate, intramucosal PCO2, PCO2 gap (difference between gastric mucosal and arterial PCO2), and systemic and mesenteric oxygen extraction ratio. Lactated Ringers given 32ml/kg/hr is was able to restore the systemic hemodynamic parameters However these same LRS doses were NOT ABLE to correct gut mucosal PCO2 gap.(14)

2. Plasma volume decreases in sepsis because of capillary leaks. Hetastarch 6% re-establishes plasma oncotic pressure and lost plasma volume. Ringer's lactate solution does not.(15)

3. In pancreatitis LRS, even at 150 ml/kg failed to achieve a normal value for effective circulating plasma (ECP) volume, resulting in 100% mortality, where as hypertonic saline was able to achieve ECP volume.(16)

4. Limited resuscitation from uncontrolled hemorrhage with hypertonic saline (7.5%) and dextran was successful in reversing the systemic hypotension, whereas LRS infusion was not able too.(17)

5. Use of saphenous and femoral veins to deliver emergency drugs and fluids only is delayed 1.5 seconds in cases where the caudal vena caval is compressed, exhibiting the extensive collateral circulation that is present.(18)

6. Hypertonic saline (7.5%) decreases perioperative weight gain following major surgery compared to normal saline.(19)

7. Albumin decreases lung cytokines, hydrogen peroxide, and pulmonary edema compared to Ringer's lactate used in hemorrhage and endotoxemia.(20)

8. Tissue oxygen levels during severe hemorrhage resulting in MAP of 40 mmHg are less than 20 mmHg in the liver and deltoid muscle. It is improved with the administration of 100% oxygen following the shock. Comparing the rapid administrations of either hypertonic saline - dextran (4 ml/kg), LRS (12 ml/kg), and Oxyglobin (6 ml/kg) resulted in the later being the most effective in restoring and maintaining mean arterial pressure (MAP) and systolic blood pressure and tissue oxygenation.(21)

9. Tissue oxygenation levels are improved effectively using low volume resuscitation of Oxyglobin compared to LRS in severe hemorrhagic shock. To provide "similar" tissue oxygenation and improve MAP levels from 60-80 mmHg) much more LRS is required compared to autologus blood, LRS with an equal volume of blood than was anticipated. For a hemorrhage of > 40% of the animals (swine) blood volume(a 2000 ml hemorrhage) resulting in an MAP of 30 mmHg > 16,000 ml was required of LRS alone, 4,700 ml for a mixture of autologus blood and LRS, 1500 ml for blood alone, and 450 ml for Oxyglobin. This low volume of Oxyglobin also reverses low tissue pH and high lactate levels more effectively than the high volumes of LRS.(22). This has also been seen in clinical cases in the author's experience too.

10. Under acute volume loss peak expansion of vascular volume with LRS is immediate after its infusion but is only 50% as effective as hetastarch which takes 5 minutes after its completion of its infusion.(23)

11. LRS and hetastarch but not plasma resuscitation after rat hemorrhagic shock is associated with immediate lung apoptosis by the up-regulation of the Bax proteins within mitochondrial membranes. Hetastarch created less cellular injury than the LRS. Mitochondrial edema was lest with plasma and most with LRS. Cells affected the most are those in the perivascular and peribronchial spaces.(24)

12. Use speed and strength of jugular vein filling after digital occlusion and saphenous vein emptying when raising the leg with the patient in lateral recumbency to determine venous volume and as an indication of when the "gas tank" or distributive "storing" volume is filled when fluid therapy is provided(3,9). Central venous pressure may also be used to help establish when "the tank is filled"

13. Use arterial pulse pressure, or the difference between systolic and diastolic pressure as an indication of stroke volume and the speed of the climb of arterial wave forms for estimating the force of contraction.(9). Consider the arterial side of the circulation as the "gas line". Not until the gas tank (venous side of the circulation) is getting low or near "empty" will the gas line not have sufficient volume to provide the pressure needed to run the system.(6)

14. Use of hemoglobin based oxygen carriers (HBOCs) such as Oxyglobin significantly increases brain oxygen tension in animals with hemorrhagic shock and has been suggested as a fluid of choice when head injury is also present. (25)

15. Hypertonic saline is beneficial over normal fluids in patients with head or lung injury by both its effects on preventing edema and its effects on vascular endothelium. It also helps by improving intestinal perfusion in both hemorrhagic and endotoxic shock. (26-28). It literally pulls fluid out of edema brain tissue; directly improves regional cerebral blood flow by decreasing endothelial edema; shrinks red cells making them having more ability to travel through small capillaries; helps in the restoration of normal intracellular concentrations of sodium and chloride which are low in head and lung trauma which restores normal membrane potentials; stimulates the release of plasma atrial natriuretic peptide and this peptide increases blood flow to certain parts of the brain directly and reduces ICP in global cerebral ischemia. It also causes vasodilation of both systemic and pulmonary vessels and increased cardiac contractility (29).

Other practical, but not widely known treatments in emergency patients include the following:

1. SALINE ENEMAS - Decrease the fecal load as soon as possible following shock resuscitation and in cases with foul smelling or blood diarrhea as research has shown an increase in survival in animals that have a 30ml/kg saline enema after the experimental induction of acute necrotizing pancreatitis.(30)

2. ALLOPURINOL - At 50 mg/kg allopurinol, a xanthine oxidase inhibitor protects the stomach, intestine, liver, and pancreas of dogs from damage due to gastric dilation volvulus and other forms of shock.(31)

3. PENTOXIFYLLINE - The use of this xanthine derivative inhibits the production of oxygen radicals of polymorponuclear neutrophils (PMNs) and their adherence to endothelial cells by inhibiting the expression of adhesion molecules on the cell surface of the PMNs. It also reduces the production of inflammatory cytokines, in particular TNFalpha, and prevents platelet aggregation. It also improves perfusion of the microvascular bed and tissue oxygenation. At a dose of 30-50 mg/kg pentoxifylline has been shown experimentally to improve the clearance of bacteria and endotoxin and survival from septic and hemorrhagic shock respectively.(32)

4. HYDRCORTISONE - Stress doses of hydrocortisone have been responsible in helping arrest the need for positive vasopressors(dopamine, norepinephrine, or epinephrine) in patients in septic shock. The doses recommended are 1.3 mg/kg as a loading bolus, then 0.18 mg/kg/hr until the shock was reversed and then 0.08 mg/kg/hr. As soon as the underlying infection is under control the steroid dose is decreased slowly over days. This finding is thought be due to a relative adrenocortical insufficiency in septic shock.(34)

5. LIDOCAINE - Ischemia-reperfusion injury in shock is decreased with the infusion of lidocaine at 50 mcg/kg/min after a loading bolus infusion over a few minutes of 2 mg/kg.(35)

6. METHYLPREDNISOLONE - This rapid acting corticosteroid has a protective effect on dogs in severe hemorrhagic shock. The mechanism mainly involves the anti-lipid peroxidation activity of the drug. Positive results were observed in doses as low as 4 mg/kg when given at the onset of fluid resuscitation. Levels of superoxide dismutase (SOD) remain higher in dogs given methylprednisolone (36).

7. PROMAZINE TRANQUILIZERS - Contrary to popular belief the use of chlorpromazine has been shown to enhance microvascular blood flow of the splanchnic circulation in dogs with hemorrhagic shock (37). Chlorpromazine has also been shown to help prevent acute respiratory distress syndrome in animals subject to trauma.(38)

N-ACETYLCYSTEINE - At doses of 150 mg/kg begun at the onset of fluid resuscitation in hemorrhagic shock N acetylcysteine preserved splanchnic blood flow and reduced hepatic damage caused by reperfusion injury as the drug provides glutathione for the replenishment of SOD and has a preservation effect on hepatic blood flow during shock and resuscitation.(39)

OXYGEN - This drug should be given in as high a concentration as possible, preferably near 100%, when shock is present and some research suggests that it is best given prior to fluid infusion as this leads to less reperfusion injury than if given after infusion is done.(40)

ANALGESICS - A land mark study proved that pain can contribute to a patient's mortality. In a study involving human infants that all underwent a reparative cardiac surgery those that did not receive constant rate infusions of sufentanyl had a 23% improved survival rate over those that only received the sufentanyl whenever the infants were noted to be in discomfort. The pain was associated with higher levels of catecholamines, cortisol, lactate, and vasoconstriction and increased.(41). Therefore it is key in this authors opinion that both anxiety and pain be controlled in the critically ill patient to provide the most optimal chance for recovery in emergency situations lending to these.

General Critical Care Guidelines - All critical patients should receive specific assessment and supportive care also in the following areas: Nutrition (both enteral and parenteral); Fluids and electrolytes; Gastrointestinal protection and support of liver, pancreas, and kidney function; Musculoskeletal (in the form of physical therapy; Dermal assessment and protection; Emotional support for the patient, owner, owners family; Emotional support that also extends to those providing the care for the critical patient. As a general guideline all patients should receive enteral support within 12 hours of hospital admission.

REFERENCES

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2. Crowe, DT: Clinic and staff readiness: Key to successful outcomes in emergency care. Veterinary Medicine 2003; 98(9):760-776.

3. Crowe, DT: A general approach to emergency patients. Veterinary Medicine 2003; 98(9):777-786.

4. Crowe DT: Supplemental oxygen therapy in critically ill or injured patients. Veterinary Medicine 2003; 98(11):935-953.

5. Crowe, DT: Support ventilation of the acutely traumatized dog and cat. In Proceedings of American College of Veterinary Emergency and Critical Care Postgraduate Review Course of 2005: Traumatology, Jan 15, 2005, Phoenix, AZ pg 9-34.

6. Crowe, DT: Canine resuscitation from shock. Advances in Critical Care Medicine: Update for the Veterinary Specialist. 12: 1-4, Dec. 2003

7. Crowe, DT: Severe thoraco-abdominal trauma, In Proceedings of American College of Veterinary Emergency and Critical Care Postgraduate Review Course of 2005: Traumatology, Jan 15, 2005, Phoenix, AZ pg 39-47.

8. Crowe DT: Rapid sequence intubation and surgical intervention in respiratory emergencies. Veterinary Medicine 98(11):954-968.

9. Guyton, AC: Overview of the circulation, and medical physics of pressure, flow, and resistance. In

Textbook of Medical Physiology, 8th Ed, WB Saunders, Philadelphia, 1991 pg 150-158.

10. Spreng DE, DeBehnke DJ, Crowe DT, et al: Evaluation of an esophageal Doppler probe for the identification of experimental pseudo-electricomechanical dissociation: a preliminary study. Resuscitation. 1995, 29(2):153-156.

11. Crowe DT: Evaluation of a Doppler flow detector and probe on the eye fro determining effectiveness of blood flow generation with cardiac massage in dogs. Scientific Proceedings of the Third International Veterinary Emergency and Critical Care Symposium, Sept 20-23, 1992. Veterinary Emergency and Critical Care Society, San Antonio, TX, 1992. pg 837.

12. Crowe DT, Kovacic J, Kirby B: Evaluation of a Doppler flow detection for clinical assessment of effectiveness of cardiopulmonary cerebral resuscitation in dogs and cats. Scientific Proceedings of the Third International Veterinary Emergency and Critical Care Symposium, Sept 20-23, 1992. Veterinary Emergency and Critical Care Society, San Antonio, TX, 1992. pg 839.

13.Ackland, G, Grocott, MPW, Mythen, MG: Understanding gastrointestinal perfusion in critical care: so near, and yet so far. Crit Care. 2000, 4(5):269-281.

14. Logoa CE, de Figueiredo FF, Cruz RJ, et al: Effects of volume resuscitation on splanchnic perfusion in a canine model of severe sepsis induced by live Escherichia coli infusion. Crit Care 2004, 8(4):R221-228.

15. Marx G, Cobas MM, Schuerholz T, et al: Hydroxyethyl starch and modified gelatin maintain plasma volume in a porcine model of septic shock with capillary leakage. Intensive Care Med 2002, 28(5):629-635.

16. Kondo Y, Nagai H, Kasahara K, et al: The therapeutic effect of hypertonioc solutions on changes in effective circulating plasma volume in acute necrotizing pancreatitis in rats. Surgery Today. 1998:28(12)

17. Doucet JJ: Limited resuscitation with hypertonic saline, hertonic sodium acetate, and lactate Ringer's solution in a model of uncontrolled hemorrhage from a vascular injury. J Trauma. 1999 47(5):956-963.

18. Stylianos S, Jacir NN, Hoffmann MA., et al: Experimental volume replacement through lower extremities. J Trauma 1993, 35(5): 666-669.

19. Jarvela K, Kaukinen S: Hypertonic saline (7.5%) decreases perioperative weight gain following cardiac surgery. J Cardiothoracic Vasc Anesth. 2002;16(1):43-46.

20. Zhang H, Voglis S, Kim CH, et al: Effects of albumin and Ringer's lactate on production of lung cytokines and hydrogen peroxide after resuscitated hemorrhage and endotoxemia in rats. Crit Care Med. 2003;31(5):1515-1522.

21. Knudson MM, Lee S, Ericson V, et al: Tissue oxygenation monitoring during hemorrhagic shock and resuscitation: a comparison of LRS, hypertonic saline dextran and HBOC-201. J Trauma 2003;54(2):242-252.

22. McNeil JD, Smith DL, Jenkins DH, et al: Hypotensive resuscitation using a polymerized bovine hemoglobin based oxygen-carrying solution (HBOC-201) leads to reversal of anaerobic metabolism. J Trauma 2001,50(6):1063-1075. (use this reference at the end of the first sentence that ends on page 15 "carrier (HBOC)". (use this reference also after second sentence under Fluid Resuscuitation on page 14 ...interstitial edema will result.

23. McIlroy DR, Kharasch ED: Acute intravascular volume expansion with rapidly administere cyrstalloid or colloid in the setting of moderate hypovolemia. Anesth Analg 2003; 96(6):1572-1577.

24. Deb S, Martin B, Sun L, et al: Resuscitation with lactated Ringer's solution in rats with hemorrhagic shock induces immediate apoptosis. J Trauma 1999, 46(4):582-589.

25. Manley G, Morabito D, Hemphill J, et al: Effect of small-volume resuscitation with hemoglobin substitute HBOC-201 on brain tissue oxygenation following experimental hemorrhagic shock. J Trauma 2000; 48:195-201.

26. Qureshi AI, Suarez JI: Use of hypertonic saline solutions in the treatment of cerebral edema and intracranial hypertension. Crit Care Med 2000; 28(9):3301-3313.

27. Oi, Y, Aneman A, Svensson M, et al: Hypertonic saline - dextran improves intestinal perfusion and survival in porcine endotoxin shock. Crit Care Med 2000; 28(8):2843-2850.

28. Cone JB, Bowser BH, Caldwell FT: Prevention of pulmonary dysfunction secondary to hemorrhage by resuscitation with a hypertonic solution (in dogs). Current Surgery 1981; 149:144-145.

29. Kramer GC: Hypertonic resuscitation: physiologic mechanisms and recommendations for trauma care. J Trauma. 2003: 54(5 Suppl):S89-99.

30. Marotta F, Geng TC, Wu CC. et al: Bacterial translocation in the course of acute pancreatitis: beneficial role of nonabsorbable antibiotics and lactitol enemas. Digestion. 1996;57(6):446-452.

31. Guilford WG, Komtebedde J, Haskins SC, et al: Influence of the allopurinol on the pathophysiology of experimental gastric-dilation. J Emergency and Critical Care. 1996;5(1):51-60.

32. Heller S, Weber K, Heller A, et al: Pentoxiflylline improves bacterial clearance during hemorrhage and endotoxemia. Crit Care Med. 1999; 27(4):756-762.

33. Wang P, Zheng FB, Stepp KJ, et al: Pentoxifylline attenuates the depressed endothelial cell fuction and vascular muscle contractility following trauma and hemorrhagic shock. J Trauma. 1995;39(1):121-129.

34. Briegel J, Forst H, Haller M, et al: Stress doses of hydrocortisone reverse hyperdynamic septic shock: A prospective, randomized, double-blind, single-center study. Crit Care Med 1999;27(4):723-732.

35. Keith JC: Effect of lidocaine pretreatment on acute hemorrhagic shock in the anesthetized rat. Circ Shock 1986;19(3):283-292.

36. Xia F, Cao JS, Zhan LY, et al: Effect of methylprednisolone on reperfusion injury in severe uncontrolled hemorrhagic shock. Chin J Traumatol. 2003;6(6):359-362.

37. Gowdey CW, Kilborn RM, Stevenson JA: Treatmentb of hemorrhagic shock in dogs with chlorpromazine and/or hypothermia. Can J Biochem Physiol 1957;35(12):1241-1248.

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BLUNT AND PENETRATING TRAUMA PROTOCOL

Take Safety Precautions (cover with towel or muzzle, BSI if possible human blood exposure on the dog)

Assess Level of Consciousness (LOC) ability to move

Semiconscious ® provide blow-by oxygen

Assess For Kill Zone Injury (Examine Head, Neck, Chest, Abdomen, Back, Pelvis, Inguinal regions)

Provide High flow Blow By Oxygen (2-5 LPM)

Assess Airway ® Provide a patent airway (see airway protocol)

Ventilate with Bag-Valve Mask with reservoir and 10/min O2

If difficulty in providing air/oxygen into airway perform rapid Intubation with rapid sequence ketamine, butorphenol

Assess cardiovascular system (pulse rate and strength, heart tones, vein distension, mucus membrane color, extremity temperature, reassess consciousness and breathing ® start large bore IVs (minimum of two 16 g prefer at least one in a front limb or jugular vein)

Assess abdomen, pelvis or inguinal region or rear legs for expansion ® if seen apply gentle counterpressure on pelvic limbs, pelvis, and abdomen. Leave enough looseness to allow a hand to be able to be placed between the abdomen counterpressure devices (towels, bubble wrap, or bandages).

If dog objects to counterpressure inject ABK (Acepromazine, Burorphenol, Ketamine) and Immobilize dog on board with duct tape over wing of ilium, chest-abdomen intersection, and wing of the atlas.

Assess Limb Injury – Apply dressing to cover wound IF patient is stable.

If not stable cover the entire patient with blanket and transport immediately to nearest identified Life Support Hospital (these should be identified ahead of time). All Life Support Hospitals should have on hand several bags of Oxyglobin minimum.

Special GSW (gun shot wound) situations:

Special Impalement Situations:

Keep the patient warm. Wrap in blankets as required.

Minimize movement to keep clots from becoming disrupted.

Keep the patient comfortable; request analgesics and sedation and even anesthetize if important to prevent hypertension and struggling that could be disastrous.

Call ASAP to notify emergency receiving hospital that the dog is coming as soon a it is known.

Provide Oxyglobin as a blood "substitute" for up to 30 ml per Kg body weight to keep pressures.

Consider a nasal-pharyngeal oxygen catheter and a rate of 5 LPM in animals injured but have not yet found a new home..

Monitor Vital Signs and LOC every 5-10 mintes and record. Provide the trends to the receiving veterinarian.

Although transportation should be done expeditiously there are times when this must be delayed until immediate care for an immediate life-threatening condition is completed; example a sucking chest wound or a severe hemorrhage coming from the right femoral vein.

Surgical exposure and clamping of a significantly bleeding vessel should be done as needed = indications are: Severely rapidly expanding thigh region, blood flowing from the right jugular vein; both indicating the need for immediate hemorrhage control with exposure and vascular clamping.