I85PREP
⌘ K
CNA Cardiovascular Nursing (CCN(C)) study materials
CNA Cardiovascular Nursing (CCN(C)) study resources

Narrow Pulse Pressure and a Blunted Y Descent After STEMI

CNA Cardiovascular Nursing (CCN(C)) · Put your knowledge to work in context.

All case studies

Narrow Pulse Pressure and a Blunted Y Descent After STEMI

Mr. Kowalski, 58, is day 3 after an anterior STEMI with a moderate pericardial effusion noted on echo. At 07:00 he reports increasing breathlessness when lying flat and a "tight" feeling in his chest. Vital signs: BP 96/78 mmHg (earlier 128/76), HR 118 sinus tachycardia, RR 26, SpO2 93% on 2 L, temperature 36.8 °C. His extremities are cool, and the arterial line waveform shows 14 mmHg of respiratory variation in systolic pressure. CVP reads 18 mmHg with a blunted y descent. Heart sounds are difficult to hear over the monitor noise. Urine output was 20 mL for the last hour. The night nurse charted 500 mL of urine over the previous shift and gave furosemide 40 mg IV at 05:00 for "volume overload."

1. Which findings point to a mechanical cause rather than left ventricular pump failure, and what will you do in the next 15 minutes?

Read the worked answer

Pattern recognition

  • Narrow pulse pressure (96/78) with new hypotension, sinus tachycardia, and cool, poorly perfused extremities.
  • CVP of 18 mmHg with a blunted y descent: early diastolic filling is impaired by external compression, not by a stiff, failing ventricle.
  • Pulsus paradoxus of 14 mmHg on the arterial trace plus muffled heart sounds, in a patient with a known effusion.
  • The deterioration began after IV furosemide, which is the physiological fingerprint of a preload-dependent circulation.

Pump failure would more typically show crackles, an S3, a prominent y descent once filling pressures normalise, and a CVP that responds to diuresis rather than worsening after it.

Next 15 minutes

  1. Stay at the bedside; continuous ECG, arterial pressure and SpO2; repeat 12-lead.
  2. Call the cardiologist and attending now, stating the tamponade pattern explicitly.
  3. Prepare for urgent bedside echo and pericardiocentesis: tray, ultrasound, large-bore IV access, fluid warmer, defibrillator pads on.
  4. Position supine or head-up only as tolerated; avoid nitrates, sedatives and further diuretics.
  5. Document the temporal link to furosemide and hand this over verbally at every transfer.

2. The resident orders a second dose of IV furosemide. How do you respond, and what do you propose instead?

Read the worked answer

I would not administer it and would escalate immediately rather than simply record the order.

Reasoning to state to the prescriber

  • In tamponade, stroke volume is fixed by external compression; the ventricle is entirely preload-dependent. A diuretic removes the only remaining contributor to cardiac output.
  • The evidence is in the chart: BP fell from 128/76 to 96/78 and urine output collapsed after the 05:00 dose, alongside a CVP that stayed high with a blunted y descent.
  • More diuresis risks electromechanical deterioration and PEA arrest.

Counter-proposal

  • Hold the diuretic; obtain an urgent bedside echo and cardiology review for drainage.
  • If hypotension persists while drainage is arranged, a cautious crystalloid bolus (250 mL, reassessed) may temporise.
  • Escalate through the chain of command if the order is repeated; ask for the decision and rationale in writing and document my concerns and the notification times.

3. At 08:20 the BP falls to 78/54, HR rises to 132, and the patient is drowsy. Explain the physiology and list your actions in order.

Read the worked answer

Physiology: this is pre-arrest tamponade, trending toward PEA. Compressive pericardial pressure has equalised with diastolic filling pressure, so stroke volume is near-fixed and the tachycardia can no longer compensate. Drowsiness reflects cerebral hypoperfusion, not sedation.

Actions, in order

  1. Call the arrest/rapid response team and the cardiologist; announce "possible tamponade, peri-arrest."
  2. Oxygen at high flow; do not delay drainage for investigations.
  3. Rapid 250–500 mL crystalloid bolus while preparing the tray.
  4. Definitive treatment: emergent pericardiocentesis, performed without waiting for a confirmatory echo if the patient is peri-arrest. Prepare the tray, ultrasound, and a drainage system with three-way tap.
  5. Apply defibrillator pads; be ready for PEA arrest and CPR.
  6. Anticipate that positive-pressure ventilation will further reduce venous return - if intubation is required, expect worsening hypotension and plan fluids and vasopressor support with the team.
  7. Send the drained fluid for analysis; document volumes and the haemodynamic response.