Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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  Blood Pressure Monitoring Basics
  Angela Dyer-Corso
  May, 2004

I.  Blood Pressure

A.     Adequate blood pressure is necessary to ensure that oxygen in the blood stream makes it from the lungs to the brain and major organs. 

B.     The Cardell unit measures:

                                                   i.      SAP:  Systolic Arterial Pressure – the pressure in the arteries when the heart pumps.  SAP should ideally be maintained > 100

                                                 ii.      DAP:  Diastolic Arterial Pressure – the pressure in the arteries when the heart is relaxed (between pumps).  In general, DAP should be > 40.  A decrease in DAP indicates that the patient’s arterioles (smallest arteries) are beginning to relax, which is usually an indication that the patient is too deep.

                                                iii.      MAP:  Mean Arterial Pressure – an average pressure in the arteries over the entire cardiac cycle (heart beat) calculated from the SAP and DAP measurements.  MAP should ideally maintained >70.  At levels below 60 blood flow to major organs is impaired, which could result in organ damage.

C.     If the blood pressure readings are too low:

                                                   i.      Check the patient!

                                                 ii.      Decrease the inhalant anesthetic setting

                                                iii.      Increase the oxygen flow rate and squeeze out the bag

                                               iv.      Increase the IV fluid flow rate (check with the Dr. first of course)

1.      Think of watering a lawn.  If the hose is set really low, the pressure is low and not all of the lawn gets watered.  If you turn up the hose, the pressure goes up and more of the grass gets watered.

                                                 v.      Check the cuff to ensure proper placement/positioning

1.      Location: below the elbow, above or below the hock (ankle), or tail base

2.      Selection:  cuff size should be 40% of the circumference of the selected location.  So, hold the cuff up to the desired location and turn is sideways – it should go roughly halfway around the limb or tail.



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