Rosen & Barkin's 5-Minute Emergency Medicine Consult (369 page)

• Preeclampsia
  :
  
  • Definition: SBP >140 or DBP >90 mm Hg with proteinuria (>300 mg/24 hr or a urine protein/creatinine >0.3 or dipstick 1+)
    
  • Occurs >20 wk gestation – 4 wk postpartum
    
  • Headache, vision changes, peripheral edema, RUQ pain
    
  • Complications: Eclampsia, HELLP
    
  • Goal: SBP 130–150 mm Hg and DBP 80–100 mm Hg
    
  • Drug of choice: Labetalol, nicardipine, hydralazine, magnesium
    
  • Consult Obstetrics
    
• Esmolol:
  
  • β1-blockade
    
  • Onset 60s, duration 10–20 min
    
  • Avoid in AHF, COPD, heart block
    
• Labetalol:
  
  • Combined α- and β-blocker
    
  • Onset 2–5 min, duration 2–6 hr
    
  • No reflex tachycardia due to β-blockade
    
  • Avoid in: COPD, AHF, bradycardia
    
• Clevidipine:
  
  • 3rd generation dihydropyridine CCB
    
  • Onset 2–4 min, duration 5–15 min
    
  • Elimination independent of liver/renal function
    
  • Avoid in allergies to soy or egg products, defective lipid metabolism, AFib
    
• Nicardipine:
  
  • 2nd generation dihydropyridine CCB
    
  • Onset 5–15 min, duration 4–6 hr
    
  • Avoid in: AHF, coronary ischemia
    
• Nitroglycerin:
  
  • Venous > arteriolar dilation
    
  • Onset 2–5 min, duration 10–20 min
    
  • Perfuses coronaries, decreasing ischemia
    
  • Causes reflex tachycardia, tachyphylaxis, methemoglobinemia
    
• Nitroprusside:
  
  • Short-acting arterial and venous dilator
    
  • Onset 3 s, duration 1–2 min
    
  • Complications:
    
    • Reflex tachycardia, “coronary steal”, increase ICP
      
    • Cyanide toxicity after prolonged use
      
  • Avoid in pregnancy, renal failure (relative)
    
• Hydralazine:
  
  • Arteriolar dilator
    
  • Onset 5–15 min, duration 3–10 hr
    
  • Hypotensive effect may be less predictable
    
  • Safe in pregnancy
    
• Enalaprilat:
  
  • ACE inhibitor
    
  • Onset 0.5–4 hr, duration 6 hr
    
  • Avoid in: Pregnancy, AMI
    
• Fenoldopam:
  
  • Selective postsynaptic dopaminergic receptor agonist (DA1)
    
  • Onset 5–15 min, duration 1–4 hr
    
  • No reflex tachycardia
    
  • Maintains renal perfusion
    
  • Avoid in: Glaucoma
    
• Phentolamine:
  
  • α1-blocker, peripheral vasodilator
    
  • Onset 1–2 min, duration 10–30 min
    

• Clevidipine: 1–16 mg/h IV infusion
  
• Enalaprilat: 1.25–5 mg q6h IV bolus
  
• Esmolol: 80 mg IV bolus, then 150 μg/kg/min infusion
  
• Fenoldopam: 0.1–0.6 μg/kg/min IV infusion
  
• Hydralazine: 10–20 mg IV bolus
  
• Labetalol: 20–80 mg IV bolus q10min (total 300 mg); 0.5–2 mg/min IV infusion
  
• Nicardipine: 2–15 mg/h IV infusion
  
• Nitroglycerin: 5–100 μg/min IV infusion; USE NON-PVC tubing
  
• Nitroprusside: 0.25–10 μg/kg/min IV infusion
  
• Phentolamine: 5–15 mg q5–15min IV bolus
  

FOLLOW-UP

• All patients with end-organ damage
  
• ICU for cardiac and BP monitoring
  

• Absence of end-organ damage
  
• Likely to be compliant with primary care
  
• Known history of HTN
  
• Reversible precipitating cause (e.g., medication noncompliance)
  
• Able to resume previous medication regimen
  
• Return with chest pain or headache
  

Initiation of a suitable medication regimen under care of a primary care provider

• Avoid IV agents for hypertensive urgency
  
• BP goal in hypertensive emergency is a reduction of the MAP by 20–25% within the 1st hr except in ischemic CVA and aortic dissection
  
• Avoid excessive or precipitous decrease in BP because it may exacerbate end-organ damage
  
• Avoid reflex tachycardia in aortic dissection
  
• Avoid unopposed α in catecholamine excess
  

• Johnson W, Nguyen ML, Patel R. Hypertension crisis in the emergency department.
  Cardiol Clin
  . 2012; 30(4):533–543.
  
• Marik PE, Rivera R. Hypertensive emergencies: An update.
  Curr Opin Crit Care
  . 2011;17:569–580.
  
• Ram CV, Silverstein RL. Treatment of hypertensive urgencies and emergencies.
  Curr Hypertens Rep.
  2009;11(5):307–314.
  
• Rhoney D, Peacock WF. Intravenous therapy for hypertensive emergencies, part 1.
  Am J Health Syst Pharm
  . 2009;66(15):1343–1352.
  
• Rhoney D, Peacock WF. Intravenous therapy for hypertensive emergencies, part 2.
  Am J Health Syst Pharm
  . 2009;66(16):1448–1457.
  

See Also (Topic, Algorithm, Electronic Media Element)

• Acute Coronary Syndrome
  
• Acute Stroke
  
• Aortic Dissection
  
• Congestive Heart Failure
  
• Preeclampsia/Eclampsia
  
• Subarachnoid Hemorrhage
  

CODES

• 401.9 Unspecified essential hypertension
  
• 437.2 Hypertensive encephalopathy
  

BASICS

• Range of progressively more severe illnesses due to increasingly overwhelming heat stress
  
• Begins with dehydration and electrolyte abnormalities and progresses to thermoregulatory dysfunction and multisystem organ failure
  
• Body temperature is maintained within a narrow range by balancing heat production with heat dissipation
  
• Oxidative phosphorylation becomes uncoupled and essential enzymes cease to function above 42°C (108°F)
  

• Core body temp >105°F (40.5°C)
  
• Failure of thermoregulatory function leads to severe CNS dysfunction and multisystem organ failure
  
• Classic heat stroke (nonexertional)
  
  • Occurs in patients with compromised thermoregulation or an inability to remove themselves from a hot environment (e.g., extremes of age, debilitated)
    
  • Develops over days to weeks, usually during heat waves
    
  • Severe dehydration, skin warm and dry
    
• Exertional heat stroke
  
  • Younger, athletic patients with combined environmental and exertional heat stress (e.g., military recruits)
    
  • Develops over hours
    
  • Internal heat production overwhelms dissipating mechanisms, often despite persistent sweating
    

• Core temp moderately elevated but usually <104°F (40°C)
  
• Fluid and/or salt depletion occurs secondary to heat stress
  
• Thermoregulatory function is maintained and CNS function is preserved
  
• Variable nonspecific symptoms including malaise, headache, fatigue, and nausea
  
• If left untreated, progresses to heat stroke
  

• Pre-existing conditions that hinder the body’s ability to dissipate heat predispose for heat-related illness
  
  • Age extremes
    
  • Dehydration (incl. gastroenteritis, inadequate fluid intake)
    
  • Cardiovascular disease (incl. CHF, CAD)
    
  • Obesity
    
  • Diabetes mellitus, hyperthyroidism, pheochromocytoma
    
  • Febrile illness
    
  • Skin diseases that hinder sweating (incl. psoriasis, eczema, cystic fibrosis, scleroderma)
    
• Pharmacologic contributors
  
  • Sympathomimetics
    
  • LSD, PCP, cocaine
    
  • MAO inhibitors, antipsychotics, anxiolytics
    
  • Anticholinergics
    
  • Antihistamines
    
  • β-blockers
    
  • Diuretics
    
  • Laxatives
    
  • Drug or alcohol withdrawal
    
• Environmental factors
  
  • Excessive heat/humidity
    
  • Prolonged exertion
    
  • Lack of mobility
    
  • Lack of air conditioning
    
  • Lack of acclimatization
    
  • Occlusive, nonporous clothing
    

Children are at increased risk of heat illness due to increased body surface area to mass ratio and lower sweat production

DIAGNOSIS