Blood Pressure Measurement: Indirect

By | 2013-07-26

Patient Preparation

None required.

Technique

Generally, two techniques are used. Oscillometric blood pressure (BP) measurement entails use of an automated recording system. A cuff is applied to the base of the tail or a distal limb for access to an artery. This technique generally is regarded as being most accurate in dogs. When oscillometric BP measurements are performed in dogs, the patient should be in lateral recumbency. This places the cuff at approximately the same level as the heart. In cats the patient generally remains in sternal recumbency (and minimally restrained). Most patients experience a brief acclimation period to the cuff placement. For this reason, at least three to five separate readings are obtained at 1- to 2-minute intervals. This technique can be used on awake or anesthetized patients ().

The Doppler-ultrasonic flow detection system is most accurate in cats for measuring systolic BP. Again, the ventral tail base or a dorsal pedal artery (hindlimb) or the superficial palmar arterial arch (forelimb) can be used. Apply and inflate an occluding cuff. The readings are obtained by a transducer as the pressure on the cuff is reduced. Caution is recommended in interpreting results from dogs that are reported as hypertensive but have no overt clinical disease. The higher reported occurrence of falsely elevated BP in normotensive dogs measured by this method justifies additional scrutiny when interpreting Doppler BP results in dogs.

TABLE Systolic Blood Pressure

  Normal Hypertension Hypotension  
Dog and cat 100-150 mm Hg > 160 mm Hg

>180mmHg(high risk)

<100mmHg  

Clinically, the most common use of indirect BP measurement is in assessing cats for the presence (or absence) of systemic hypertension caused by renal insufficiency or hyperthyroidism (thyrotoxicosis). A common finding among untreated hypertensive cats is retinal detachment and blindness. Early detection and therapeutic intervention (e.g., enalapril and or amlodipine) is critical. In dogs, BP measurement is indicated in patients with chronic renal insufficiency and/or protein-losing nephropathy, hyperadrenocorticism, and diabetes mellitus. In veterinary medicine, interpretation of BP centers on the systolic BP reading, not the diastolic reading (Table Systolic Blood Pressure).