STEMI - Management in ER

Question 1

In the Emergency Department, what are the goals for the management of patients with suspected STEMI?

Answer 1

1. Control of cardiac discomfort
2. Rapid identification of patients who are candidates for urgent reperfusion therapy
3. Triage of lower-risk patients to the appropriate location in the hospital
4. Avoidance of inappropriate discharge of patients with STEMI

Question 2

Medications started at ER

Answer 2

• ASA

Question 3

ASA in STEMI

• Mechanism
• Initial dosing
• Maintenance dosing

Answer 3

• Mechanism
  
  • Rapid inhibition of cyclooxygenase-1 in platelets followed by a reduction of thromboxane A2 levels
• Dosing
  
  • Buccal absorption of a chewed 160–325-mg tablet
• Maintenance dosing
  
  • daily oral administration of aspirin in a dose of 75–162 mg

Question 4

Is there a need for O₂ support for all STEMI patients?

Answer 4

• Arterial O₂ saturation is normal
  
  • Supplemental O₂ is of limited if any clinical benefit and therefore is not cost-effective
• When hypoxemia is present
  
  • O₂ via nasal prongs or face mask (2–4 L/min) for the first 6–12 h after infarction
    
    • Reassessed to determine if there is a continued need for such treatment

Question 5

What are the treatment options for control of discomfort in patients who had STEMI?

Answer 5

• Sublingual nitroglycerin
• Morphine
• Intravenous beta blockers

Question 6

Effects of NTG in STEMI

Answer 6

• Diminishes or abolishes chest discomfort
• Decreases myocardial oxygen demand (by lowering preload)
• Increases myocardial oxygen supply (by dilating infarct-related coronary vessels or collateral vessels)

Question 7

How is NTG given?

Answer 7

• Initially
  
  • Sublingual; up to three doses of 0.4 mg should be administered at about 5-min
• In patients whose initially favorable response to sublingual nitroglycerin is followed by the return of chest discomfort, particularly if accompanied by other evidence of ongoing ischemia such as further ST-segment or T-wave shifts
  
  • IV nitroglycerin should be considered

Question 8

When is NTG use contraindicated?

Answer 8

• Patients who present with low systolic arterial pressure (<90 mmHg); or
• Patients in whom there is clinical suspicion of RV infarction (inferior infarction on ECG, elevated jugular venous pressure, clear lungs, and hypotension); and
• Patients who have taken a phosphodiesterase-5 inhibitor for erectile dysfunction within the preceding 24 h, because it may potentiate the hypotensive effects of nitrates

Question 9

An idiosyncratic reaction to nitrates, consisting of sudden marked hypotension, sometimes occurs but can usually be reversed promptly by _____

Answer 9

The rapid administration of intravenous atropine

Question 10

Morphine is a very effective analgesic for the pain associated with STEMI. What are the side effects cardio-wise? How are they managed?

Answer 10

• May reduce sympathetically mediated arteriolar and venous constriction, and the resulting venous pooling may reduce cardiac output and arterial pressure
  
  • usually respond promptly to elevation of the legs, but in some patients, volume expansion with intravenous saline is required
• Vagotonic effect and may cause bradycardia or advanced degrees of heart block, particularly in patients with inferior infarction
  
  • usually respond to atropine (0.5 mg intravenously)

Question 11

How is morphine given?

Answer 11

Routinely administered by repetitive (every 5 min) intravenous injection of small doses (2–4 mg), rather than by the subcutaneous administration of a larger quantity, because absorption may be unpredictable by the latter route

Question 12

Effects of beta-blockers in managing discomfort in STEMI

Answer 12

• Presumably by diminishing myocardial O₂ demand and hence ischemia
• More important, there is evidence that intravenous beta blockers reduce the risks of reinfarction and ventricular fibrillation

Question 13

Example of a commonly employed beta-blocker regimen in pain relief of patients with STEMI

Answer 13

• Metoprolol, 5 mg IV every 2–5 min for a total of three doses, provided the patient has:
  
  • HR > 60 beats/min
  • Systolic pressure > 100 mmHg
  • PR interval < 0.24 s
  • Rales that are no higher than 10 cm up from the diaphragm
• Fifteen minutes after the last intravenous dose, an oral regimen is initiated of 50 mg every 6 h for 48 h, followed by 100 mg every 12 h

Question 14

Oral beta blocker therapy should be initiated when?

Answer 14

• Oral beta blocker therapy should be initiated in the first 24 h for patients who do not have any of the following:
  
  1. signs of heart failure
  2. evidence of a low-output state
  3. increased risk for cardiogenic shock
  4. other relative contraindications to beta blockade (PR interval >0.24 s, second- or third-degree heart block, active asthma, or reactive airway disease)

Question 15

Value of calcium antagonist is acute setting

Answer 15

Calcium antagonists are of little value in the acute setting, and there is evidence that short-acting dihydropyridines may be associated with an increased mortality risk