Prehypertension is defined as blood pressures between the 90th and 95th percentiles for age, gender, and height.¹

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  Note that these definitions are based on blood pressures across a population of nonstressed children in outpatient settings. As such, some discretion should be used in strictly applying these standards to patients under stresses of a pediatric intensive care unit.

Hypertension is defined as systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) greater than 95th percentile for age, gender, and height on at least three occasions.^1,2

Hypertensive urgency implies profound hypertension, as in hypertensive emergency, but without evidence of end-organ dysfunction.

Hypertensive emergency is a syndrome of profound hypertension (generally greater than 95th percentile for age) with accompanying end-organ dysfunction. Common systems involved include central nervous system (CNS) (encephalopathy, infarction, hemorrhage), cardiovascular (heart failure, ischemia, aortic dissection), and renal (acute kidney injury, hematuria, proteinuria).

Hypertension can be primary (essential) or secondary. Primary hypertension is rare in children, but is becoming more common as pediatric obesity becomes more prevalent.¹ Secondary hypertension is due to an inciting cause, which can be transient or sustained.

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  Transient causes common in the pediatric intensive care unit include pain, agitation, and delirium. A thorough physical exam—including assessment of other vital signs (tachypnea, tachycardia), pupils, tearing, and movements—is essential to identifying and treating these causes. This can be especially difficult to assess in patients with neurologic injury or patients treated with neuromuscular blockade.

  
  
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  Sustained causes are vast, but important considerations in the ICU are listed in Table 31-1. Hypertension, like any change in vital signs, warrants a thorough assessment of the patient, including examination, review of other vital signs (including four-limb blood pressures), input/output, past history, and medication list for clues as to the cause.

  
  
  
  
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    Accompanying bradycardia and irregular respirations could indicate elevated intracranial pressure. Intake in excess of output could indicate volume overload or renal injury. Cardiac exam, including assessment for hepatomegaly, auscultation of lungs for rales, and examining neck for jugular venous distension (or elevated central venous pressure if a central line is present), should be performed to assess for heart failure. All patients should have a thorough neurologic exam for the various causes listed in Table 31-1.

    
    
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    Initial diagnostic workup will depend on clinical assessment, but likely should include assessment of renal function via electrolytes, including blood urea nitrogen (BUN) and creatinine and a urinalysis. Consideration should be given to renal/bladder ultrasound as well. If there is reason to suspect coarctation of the aorta or other cardiac anomalies, an echocardiogram can be performed. Similarly, head imaging can be considered depending on clinical context.