Is the "hypotension" genuine

     
       

 

         
       

The first thing to ask is: is this genuine hypotension? By this I mean – what is this patient’s normal blood pressure. Remember that the principle objective of targeted therapy is to return the patient to the physiological range: the patient’s vital organs perform optimally within certain perfusion pressure limits, below which ischemia may result.

Step 1: if the patient is awake, communicating and urinating, then he is probably not hypotensive.
In intensive care, patients are often sedated and cannot interact with you, and the urinary output may be the only clinical sign of tissue perfusion. If the patient is being treated with diuretics, then this is lost. The other blunt measure of end organ perfusion is acid base balance: look at the base excess (is it negative and by how much?); does the patient have a lactic acidosis?

Step 2: is this measurement error?
When addressing the information on arterial lines and non- invasive cuffs, it is the mean pressure that is likely to be accurate. The systolic pressure may over-read with a tight cuff, or under-read with a damped arterial line trace. Often there is a considerable difference between what is being read by the arterial line and the cuff. Care givers tend to believe the measurement that is closest to the physiologic range. This is illogical. If the patient’s arterial line is reading low, and there is no objective evidence of good end-organ perfusion (mentation, urine output), then the patient is hypotensive until otherwise proven.

Step 3: go to the notes / obtain a history.
You need to establish the patient’s baseline blood pressure. Look for a measurement made at an outpatient appointment or on admission. Is the patient on antihypertensive medications? If so – has his pressure been controlled: is there evidence of end organ damage – left ventricular hypertrophy with strain on the ECG? If you do not know what the patient’s baseline blood pressure is, then assume a mean arterial pressure of 80mmHg. If you know that the patient has a history of hypertension, then it is wise to aim higher, 90mmHg at least. Regardless of the predetermined target, you must have an endpoint: i.e. drive the blood pressure upwards until the patient starts urinating.

If you have confirmed that the patient is indeed hypotensive then:

Step 4: look for an iatrogenic cause.
If the patient is being treated with agents that lower the blood pressure – propofol, midazolam, morphine, nitroprusside etc, then stop these drugs, and, if necessary, reverse their effects with phenylephrine (a specific vasoconstrictor).

Step 5: Move on an look for a cause and therapeutic strategy.

         
                   
       

         
     

       
       

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