Equine Critical Care: Patient Assessment and Stabilization

Transcription

1 Equine Critical Care: Patient Assessment and Stabilization Ashleigh Olds, DVM Aspen Creek Veterinary Hospital Conifer, CO CVMA 2013 Veterinary Technician Program Patient Assessment: A thorough physical examination is more important than anything else! Heart rate Respiratory rate Skin turgor Mucus membrane color, capillary refill time (CRT), presence or absence of toxic rims Temperature GI sounds Digital pulses Sclera injection or icterus? Posture lameness? Neurologic deficits? Wounds? General attitude and demeanor. Physical exam: Heart Auscultation 1

2 Physical exam: Heart rate Normal: bpm Auscult both right and left Bradycardia may be due to second degree AV block, high resting vagal tone should resolve with exercise or may be true pathologic Tachycardia: - Pain? Shock? Fluid or blood loss? Dehydration? Endotoxemia? Be aware of murmurs and arrhythmias - Physiologic murmur dehydration, viscous blood - Atrial fibrillation irrregularly irrregular (jungle drums) - Ventricular tachycardia need ECG - Arrhythmias may be associated with some toxins (oleander, monensin, etc) or electrolyte disturbances - Calcium, magnesium, potassium hypo or hyper Physical exam: Respiratory Rate Normal: 8-16 bpm Elevated rate: Pain? Shock? Cardiac or respiratory distress? Pneumonia? RAO? Viral or bacterial infection? Increased effort associated with abdominal pressing on expiration -> RAO Stridor, stertor? Lung sounds: Crackles? Wheezes? Tracheal rattle? Respiratory exam Check for tracheal rattle Heave line Rebreathing exam 2

3 Assess Hydration: Skin turgor interpret carefully especially in older patients (reduced elasticity) Capillary refill time should be less than 2s. Dry tacky MM, slow refill time may be indicative of dehydration or reduced circulatory volume (shock? endotoxemia?) Assess hydration: Indicators of dehydration: - Pale or tacky mm - Delayed CRT - Tachycardia - Tachypnea - Poor skin turgor - Sunken eyes - Slow jugular fill - Reduced peripheral pules Sunken eyes = severe dehydration Endotoxemia/Septic shock: Late stages of severe colic compromised intestine Anterior enteritis/proximal jejunitis Laminitis Metritis Peritonitis Pneumonia/pleuroneumonia Grain overload Colitis (C. Dificile, Potomac Horse Fever, Colitis X) 3

4 Patient assessment: Temperature Rectal temperature easy to obtain Always take PRIOR to administering medications, rectal examination Elevated temperature -> bacterial or viral infection? Will alter response to sedation profound sedation, heavy breathing Be more aware of hypothermia in foals often in conjunction with hypoglycemia Normal: 98.5 F F adults Up to F in foals. Patient Assessment: GI sounds Presence, or absence? Complete absence -> obstruction, displacement, dehydration? Hypermotility -> spasmodic colic, impending enteritis/colitis? Sand? Patient Assessment: Digital Pulses Asses strength, symmetry Feel hooves and coronary bands for heat Impending laminitis? Consider ice baths, boots? Frog support? Endotoxemia often distal extremities are ice cold, weak pulses Practice feeling normals so you can detect abnormal 4

5 Patient Assessment: Sclera Icterus/jaundice: Hepatic/liver disease Hemolysis Foals: Neonatal isoerythrolysis Injected sclera: Inflammation Sepsis foals especially Difficult labor hypoxemic syndrome dummy foal? Assessment: Posture, Lameness, Wounds, General demeanor, Neurological Deficits Initial Physical Exam: All of these factors should be evaluated in a brief exam (< 5 min) Lots of valuable information!!! May not provide a diagnosis, but helps assess patient needs and direct initial treatment, diagnostics Suggests possible diagnoses 5

6 Considerations for Isolation: Fever Nasal discharge Neurologic symptoms (EHV -1?) Diarrhea High PCV, low TP, low WBC Gloves, separate thermometer, stethescope, footbaths, barrier protocol/gowns etc. Additional Diagnostics: PCV, TP Stall side monitors Lactate Blood Glucose istat? Fibrinogen? CBC, Chemistry, Electrolytes, Blood Gas? Takes time, results may not be available immediately, may not be available onsite Veterinarian Ultrasound (chest/abdomen), Rectal examination, Abdominocentesis (belly tap) Packed Cell Volume (PCV): EDTA or heparinzed whole blood most clinics can spin down with microhematocrit tube Elevated PCV hemoconcentration = dehydration Decreased PCV Blood loss (acute or chronic?), hemolysis? Internal bleeding? Splenic enlargement? True anemia? Normal: 32-44% 6

7 Total Protein: Use refractometer on plasma portion of microhematocrit tube Normal: g/dl Elevated TP Hemoconcentration dehydration if PCV elevated also Immunoglobulins (infection, abscess, neoplasia) if PCV normal Decreased TP Protein loss? Albumin? Diarrhea, endotoxemia, colitis/enteritis, pleuropneumonia? Risks of edema, decreased oncotic pressure when rehydrating Need for plasma transfusion? Hetastarch? Hypoproteinemia: PCV/TP in dehydration: PCV TP Mild dehydration 45-50% g/dl Moderate dehydration 50-60% g/dl Severe dehydration >60% >9.0 g/dl Marked increase in PCV without TP elevation may indicate dehydration with concurrent protein loss, or splenic contraction due to endotoxin release 7

8 Stall Side Monitors: Lactate Measure of lactic acid in peripheral blood Produced by anaerobic metabolism Arterial more useful than venous, but venous most commonly and easily measured Whole blood or heparinized best if can t measure on plasma/serum Results in seconds easy to perform in the field or hospital Increased maybe due to dehydration, poor tissue perfusion, endotoxemia, hypoxemia, anemia, liver failure, etc. Lactate: Normal less than mmol/l Increased values can indicate dehydration, poor tissue perfusion, compromised organs/bowel A single value is less useful than response over time Values may initially increase with fluid therapy (flushes lactate from peripheral tissues/ecf into circulation), but should decrease over time use as an indicator for continuing IV fluids Increasing lactate in the face of treatment and fluid therapy carries poor prognosis A single very high value can carry poor prognosis, particularly in colic cases -> increased likelihood of necrotic bowel >> 5-10 mmol/l Initial lactate measurement is an important BASELINE, can direct treatment, prognosis, and estimate for care Blood glucose Easy to measure, results in seconds Whole blood Hypoglycemia and Hyperglycemia most common in neonates/foals Normal mg/dl 8

9 ISTAT Analyzer Basic parameters: electrolytes, renal values, blood gasses, lactate Advantages Handheld can use stall side and in the field Faster than other blood machines Downsides: Finicky Slides refrigerated and have a short shelf life Less complete panel Fibrinogen: Acute phase inflammatory protein unique to cattle, horses Elevations in fibrinogen coincide with systemic inflammation Normal: less than 500 mg/dl Guarded prognosis > 1000 mg/dl Easy measurement (estimate) without heat precipitation: Measure TP on refractometer from plasma (EDTA) fibrinogen present Measure TP on refractometer from serum (no fibrinogen) Difference in 0.1 mg/dl coincides with 100 mg fibrinogen Example: Plasma TP = 6.5 g/dl, Serum TP = 6.3 g/dl = 0.2 g/dl = 200 mg/dl fibrinogen Indications for fluid therapy: Dehydration Tachycardia, tachypnea, slow CRT, Dry membranes, toxic rims, Elevated PCV/TP Elevated lactate Signs of shock or endotoxemia Moderate to severe colic symptoms Electrolyte abnormalities Hypo- or hyper- glycemia Elevated renal values Ongoing losses: reflux, diarrhea, bleeding 9

10 Fluid Therapy: Goals Rapidly expand blood volume Increase blood pressure, stroke volume, tissue perfusion Improved oxygenation of tissues Better anesthetic candidates Eventually leads to fluid transfer to replace deficits in ECF and GI tract Most adult horses will correct electrolyte and acid-base disturbances on their own if kidneys are functioning and a balanced isotonic solution is given IV hard to overhydrate unless: Hypoproteinemic, hypoalbuminemia Foals, neonates Renal failure (oliguric, anuric especially) Ongoing losses (severe diarrhea creating acidosis) IV Fluid Therapy: Place 14 ga IV catheter in jugular vein aseptically. Catheter choice depending on patient but endotoxemic patients are at higher risk of thrombophlebitis If RAPID hydration is required (often pre-sx) place 10 ga IV catheter in one vein, 14 ga in other and administer bolus fluids through both. Large bore IV fluid lines (coil sets) Place fluids as high as possible for gravity feed. IV Fluid Therapy Volume to give: Maintenance + replace dehydration deficit + ongoing losses Estimate % dehydrated Maintenance = 60 ml/kg/day in adults (27 L/ 1000# horse = roughly 1L/hr) Maintenance = ml/kg/day in foals Typically give a shock bolus of 60 ml/kg IV over first 1 hour, then reduce rate as indicated unless dehydration is severe (roughly L) 10

11 IV Fluid Therapy: Crystalloid fluids: NaCl not balanced, will result in hypernatremia, hyperchloremia hypocalcemia, hypokalemia Lactated Ringers Plasmalyte Normosol Quickly re-distribute to ECF in minutes which has 3x volume as blood so need 3x more fluids to expand blood volume until ECF replenished Advantages: balanced Inexpensive Well tolerated IV fluid therapy Hypertonic saline: 7.2% NaCL 8x tonicity of plasma and ECF Expands blood volume temporarily by drawing fluid into circulation from interstitium by osmosis MUST be followed by isotonic crystalloids\ Dose: 4 ml/kg rapid IV (usually 1-2l/1000# horse) Helps support circulating blood volume in severe shock, circulatory collapse, pre-anesthetic IV Fluid Therapy Colloids: Natural: plasma, whole blood risk of rxns, need to cross match whole blood? Synthetic: Hetastarch, oxyglobin, Dextran Larger molecule size migrates more slowly expands blood volume for a longer duration Critical to incorporate some if TP or albumin is extremely low Whole blood with clotting factors important with severe blood loss, anemia, poor oxygenation Some clotting side effects with synthetics, also makes oncotic pressure hard to measure Very expensive not a maintenance fluid 11

12 Respiratory Distress: Try to determine if intra-pulmonary ie RAO, bronchospasms Oxygen Bronchodilation nebulize albuterol, clenbuterol, fluticasone Oral bronchodilators Steroids Manage environment (dust, hay) If upper airway obstruction Consider tracheostomy Endoscopy Hypothermia: Warm from inside warmed IV fluids (plus glucose?) Can put warmed fluids into the peritoneum in severe cases Dry patient if wet try to avoid vigorous rubbing which may enhance muscle trauma Get them moving to generate body heat walk them if possible Wool blankets and coolers to draw moisture keep removing as they are wet and replace with dry Severe hypothermia Scarlett: 12

13 Rattlesnake bite Establish airway nostrils may swell closed below the bony nasal passages 6-12 cc syringe cases with end cut out suture to nostrils Steroids Anti-inflammatories Antibiotics Thank you! Questions? 13