posted: 08/Nov/2016

 

A Quick Review on Shock Emergency Fluids and Dehydration Fluid Deficits

In the emergency centres we see patients requiring fluid therapy on a daily basis.  Developing a fluid plan in your practice is a simple step that can improve patient outcomes.  Below is a simplified snapshot on how we look at fluid planning in the emergency centre. 

Fluid therapy is one of the most life-saving and under utilized therapies at our disposal. 

  1. Shock
    1. Signs of shock:
      1. Collapse
      2. Tachycardia
      3. Hypothermia
      4. Crt >2sec
      5. Hypotension
    2. If an animal presents collapsed and you feel it is NOT a cardiac collapse (not blue, no crackles, SPO2 99%) then place an IV Catheter immediately and start IV Fluids (any Crystalloid) .
      1. Dogs: 90mL/kg/hr are shock rate fluids                  
        1. Give a 20-30mL/kg bolus over  10-15min and then re-assess the parameters listed above.
        2. If parameters are not corrected give another bolus!
      2. Cats: 60mL/kg/hr are shock rate fluids
        1. Give a 15mL/kg bolus over 15min and then re-assess the parameters listed above.
        2. If parameters are not corrected give another bolus!
    3. Once shock parameters have resolved you can assess hydration and cause and proceed depending on disease and status. 
    4. QUICK NOTE: A 40kg dog would need a rate of 3600mL/hr as your bolus rate giving 800mL and then re-assessing.  Most fluid pumps don’t go this high, set at 999mL/hr, and ideally place a 2nd IV line if the animal is very flat.   Do not be afraid of high numbers! They need it.
      1. 40kgx90mL/kg/hr = 3600mL/hr as shock rate
      2. 360mL0/4 = 800mL over 15min is a shock rate fluid bolus.
  2. Dehydration
    1. Many of our animals are severely dehydrated either from renal disease, HGE, vomiting/diarrhea, and many other causes.  Correcting their hydration quickly and properly is imperative.   They often need much more fluids than  ‘2x maintenance’.  Remember, an animal with >12-15% dehydration cannot properly circulate it’s blood and can lead to shock and death.
      1. Estimating Dehydration %

 

  1. Physical Examination:

% Dehydration

Clinical Findings

  •  

History of vomiting/diarrhea, no clinical findings on examination

  1.  

Mild-moderate skin tenting, dry mucous membranes, history of loss

  1.  

Marked skin tenting, dry mucous membranes, weak, sunken eyes, crt >2sec, mental depression

  1.  

Hypovolemic shock (crt >2sec, hypothermia, tachycardia, hypotension), sunken eyes, skin tenting severe, death.

 

  1. PCV/TP  
    1. Dog normal PCV 35-55%, TP 50-80
    2. Cat normal PCV 25-55%, TP 60-85
  2. Calculating Fluid Deficit:
    1. Body Weight (kg) * % dehydration (as a decimal) * 1000 = fluid deficit in mL
      1. Example: 20kg dog that is 10% dehydrated:
        1. 20*0.10*1000= 2000mL fluid deficit.
  3. Correcting Dehydration:
    1. If in shock (>10% dehydration or shock parameters) give shock rate fluids and then re-assess.
    2. If not in shock, correct hydration up to  12 hours.  In the emergency centres, we prefer to rehydrate over 6 to 8 hours unless there is another medical condition that would conflict (cardiac disease).  Your fluid plan needs to include:
  • Rehydration
  • Maintenance
  • Ongoing loss
    1. Example: 20kg dog that is 7% dehydrated:
      1. Maintenance Fluids: 20kg * 2.5mL/kg/hr = 50mL/hr
      2. First 4 hours: (remember our deficit is 2000mL)
        1. 2000mL/2 = 1000mL
        2. 1000mL/4 + Maintenance = 250mL/hr + 50mL/hr= 300mL/hr
      3. Next 8 hours:
        1. 2000/2 = 1000mL
        2. 1000/8 + Maintenance = 125mL/hr + 50mL/hr= 175mL/hr

Electrolytes:

One of the most important blood tests we can run is electrolytes.  Most clinics now have access to in-house pathology which can run electrolytes.  If you have a patient on IV fluids then you really need to be monitoring electrolytes at least once daily.  Correction of electrolytes is one of the most important steps to fluid planning.  Our standard is to collect blood and check electrolytes on arrival, select the appropriate fluid type for the situation and then recheck electrolytes every 12 to 24 hours.  Sometimes this will be much more frequent, depending on the level of derangement




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