Hypotension Post Cardiac Surgery

OVERVIEW

• Think PROVED?: pump, rhythm, obstruction, volume, (endocrine), distributive, ? = artefactual

MANAGEMENT

Errors and artifacts

• examine the patient for pulses and check for symmetry
• transducer error: check transducer, zero, level, calibrate, NIBP
• damping of waveform: assess damping co-efficient, replace
• NIBP malfunction: check cuff (size, fit, connection)
• check inotrope infusions into patient
• Radial/ central arterial monitoring discrepancy with severe vasoconstriction
• Upper limb vascular disease (radial arterial line) or obstruction (e.g. dissection or aorto-occlusive disease: femoral arterial line)

Hypovolaemia

• bleeding: check drains, dressings, CXR, give fluid, blood products, correct coagulopathy and temperature
• diuresis: check urine output and sodium, give fluids

Distributive

• vasoplegia: fluids and vasoconstrictors, consideration of methylene blue
• anaphylaxis: rash, bronchospasm, stop infusions, adrenaline, fluids
• sepsis: consider -> treat with antibiotics and source control
• vasodilator excess: stop drug, vasoconstriction
• sympathetic block (epidural): fluids, vasoconstrictors

Cardiogenic

• look for cause: LV, RV, systolic, diastolic, valves, pericardium (measure cardiac output, order ECHO)
• decreased contractility: ischaemia from thrombosis, blockage, kinking, spasm -> GTN, vasoactives and fix technical problem
• sudden removal of inotropic drug: restart

Rhythm disturbance

1. bradycardia: pace, atropine, isoprenaline, adrenaline
2. SVT: K+, Mg2+, adenosine
3. AF: K+, Mg2+, amiodarone, DC shock
4. VT: K+, Mg2+, amiodarone, DC shock

Obstructive

• tension pneumothorax: examine chest, CXR -> decompress
• patient ventilator dysynchrony: paralyse patient, examine ventilator, ABG, CXR
• tamponade: ECHO, will likely need a TOE (need to exclude one chamber tamponade)

Endocrine and metabolic (unlikely in this setting)

• severe electrolyte disturbance (e.g. hypoP, hypoCa)
• adrenal insufficiency, hypothyroidism
• severe acidosis

References and Links

LITFL

• CCC – Haemorrhage post-cardiac surgery
• CCC – Hypertension post-cardiac surgery
• CCC – Hypothermia post-cardiac surgery
• CCC – Hypoxaemia post-cardiac surgery