The first 24 hours after cardiac surgery: arrival bundle, haemodynamic and metabolic targets, early extubation, recognising low cardiac output syndrome versus vasoplegia, post-operative AF, transfusion thresholds and valve-specific points.
At the bedside
Timed steps- 1
Arrival bundle
ArrivalAttach monitoring (ECG, arterial line, CVP ± PA catheter, SpO₂, ETCO₂), check pacing box connections and settings, label and check drains, take structured handover (procedure, bypass/cross-clamp times, grafts/valve, weaning difficulty, inotropes, protamine given, TOE findings, bleeding). ABG, Hb, K⁺, Mg²⁺, Ca²⁺, glucose, lactate, ACT/coagulation, ECG and chest X-ray.
- 2
Haemodynamic targets
0–6 hTypical targets (individualise with the surgeon): MAP 65–80 mmHg (avoid hypertension — suture-line bleeding), HR 80–100/min (pace if needed), cardiac index >2.2 L/min/m², ScvO₂ >65%, lactate falling, urine >0.5 mL/kg/h.
- 3
Rewarm, ventilate, extubate early
0–6 hRewarm to normothermia but avoid >37.5 °C; lung-protective ventilation; aim for extubation within 6 h when warm, awake, not bleeding and haemodynamically stable.
- 4
Electrolytes and glucose
HourlyKeep K⁺ 4.0–5.0 mmol/L and Mg²⁺ ≥1 mmol/L (reduces arrhythmia); glucose <180 mg/dL (10 mmol/L) with an insulin infusion protocol, avoiding hypoglycaemia.
- 5
Bleeding and transfusion
OngoingMonitor drain output hourly; keep tubes patent without stripping. Restrictive red-cell transfusion (Hb <7.5 g/dL) is non-inferior in moderate–high-risk cardiac surgery (TRICS III), unless active bleeding or ischaemia.
- 6
Low cardiac output vs vasoplegia
Low output?Low BP + low CI + cold peripheries + rising lactate = low cardiac output syndrome: check rhythm/rate, preload, tamponade (echo/TOE), graft ischaemia (ECG), RV failure; then inotrope (dobutamine/milrinone/adrenaline), IABP or MCS. Low BP + normal/high CI + warm = vasoplegia: noradrenaline, then vasopressin, then methylene blue rescue (not in G6PD deficiency).
- 7
Post-operative AF
Day 1–5Occurs in ~20–40% after cardiac surgery, peaking day 2–3. Continue/restart beta-blockers when stable; correct K⁺/Mg²⁺; rate or rhythm control (beta-blocker, amiodarone); DC cardioversion if unstable; consider anticoagulation if AF persists >48 h, balancing surgical bleeding risk.
- 8
Recovery bundle
Day 1+Multimodal analgesia; delirium screening; early mobilisation; restart statin and antiplatelet therapy per surgical protocol; VTE prophylaxis once bleeding settled; AKI prevention (avoid nephrotoxins, maintain perfusion).
Low cardiac output syndrome
Dobutamine
- Dose
- 2.5–10 mcg/kg/min
- Range
- 2.5–10 mcg/kg/min
- Preparation
- 250 mg in 50 mL = 5,000 mcg/mL
- Worked example
- 70 kg at 5 mcg/kg/min = 350 mcg/min = 4.2 mL/h
Low output with high SVR, pulmonary hypertension or RV failure
Milrinone
- Dose
- 0.125–0.5 mcg/kg/min (no load)
- Range
- 0.125–0.5 mcg/kg/min
- Preparation
- 10 mg in 50 mL = 200 mcg/mL
- Worked example
- 70 kg at 0.375 mcg/kg/min = 26.25 mcg/min = 7.9 mL/h
Vasoplegia refractory to noradrenaline
Vasopressin
- Dose
- 0.01–0.04 units/min
- Range
- 0.01–0.04 units/min
- Preparation
- 20 units in 50 mL = 0.4 units/mL
- Worked example
- 0.03 units/min = 1.8 units/h = 4.5 mL/h (not weight-based)
Rescue for refractory vasoplegia
Methylene blue (methylthioninium chloride)
- Dose
- 1–2 mg/kg over 20–60 min
- Worked example
- 70 kg: 70–140 mg (7–14 mL of 1%).
Post-operative AF (rhythm control)
Amiodarone
- Dose
- 150–300 mg over 20–60 min, then 900 mg over 24 h
- Worked example
- 70 kg: 300 mg in 100 mL 5% dextrose over 30–60 min, then 900 mg in 500 mL over 24 h.
Post-operative AF rate control / prevention
Metoprolol
- Dose
- IV 2.5–5 mg over 2 min (max 15 mg); PO 12.5–50 mg twice daily
- Worked example
- Stable, warm, extubated 70 kg patient: metoprolol 25 mg PO 12-hourly from day 1.
Low output vs vasoplegia vs tamponade
| Feature | LCOS | Vasoplegia | Tamponade |
|---|---|---|---|
| Peripheries | Cold, mottled | Warm | Cold |
| Cardiac index | Low | Normal/high | Low |
| SVR | High | Low | High |
| CVP | Normal/high (high if RV failure) | Low/normal | High, may equalise with PAOP |
| Drain output | Variable | Variable | Sudden fall (clotted) or high |
| Echo | Poor LV/RV function, regional wall-motion abnormality | Hyperdynamic | Collection, chamber compression (may be localised) |
| Treatment | Optimise preload/rate, inotrope, IABP/MCS | Noradrenaline → vasopressin → methylene blue | Re-exploration |
Valve-specific post-operative points
| Operation | Key issues |
|---|---|
| Aortic valve replacement (AS) | Hypertrophied, stiff LV — needs preload and sinus rhythm; avoid tachycardia; heart block (keep ventricular wires); hypertension stresses aortic suture line |
| Mitral valve surgery | Pulmonary hypertension and RV dysfunction — avoid hypoxia, hypercapnia, acidosis; milrinone useful; AF common |
| TAVI (in ICU) | Heart block (new LBBB/CHB), vascular access bleeding, stroke, annular rupture/tamponade |
| Mechanical valve | Anticoagulation with warfarin (INR target per valve type/position) — timing of heparin bridge agreed with surgeon after drains removed |
Calculators for this topic
Infusion rate from mcg/kg/min
Pump rate in mL/h for drugs dosed in mcg/kg/min (noradrenaline, adrenaline, dobutamine, milrinone, nitroglycerin by weight).
Infusion rate from a fixed hourly or per-minute dose
Pump rate for non-weight-based infusions such as vasopressin (U/min), labetalol (mg/min) or amiodarone (mg/h).
Mean arterial pressure
(SBP + 2 × DBP) ÷ 3 (estimate; use the arterial line value when available).
Body surface area (Mosteller)
√(height cm × weight kg ÷ 3600).
References
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Hypotension in the first 24 h after cardiac surgery
Step 1 of ~5
Bedside approach before calling it LCOS or vasoplegia.
Check transducer, rhythm, pacing, drains, ABG, Hb
Based on Engelman DT, Ben Ali W, Williams JB, et al; Dunning J, Levine A, Ley J, et al. Educational use; follow local protocol.
Pathophysiology
Cardiopulmonary bypass causes systemic inflammation, haemodilution, platelet dysfunction and fibrinolysis, myocardial stunning after cross-clamping (typical nadir of function 4–6 h post-op), and vasoplegia via nitric oxide and vasopressin deficiency. Diuresis after bypass shifts K⁺ and Mg²⁺. Post-operative AF arises from atrial inflammation, sympathetic activation and electrolyte shifts.
Evidence
- ERAS Cardiac Society 2019: recommendations include perioperative glycaemic control (insulin infusion to <180 mg/dL), goal-directed fluid therapy, chest-tube patency without stripping, early extubation (<6 h), prevention of hyperthermia on rewarming, multimodal opioid-sparing analgesia, delirium screening, AKI risk mitigation and pharmacological thromboprophylaxis.
- TRICS III (2017): 5,243 moderate-to-high-risk cardiac surgery patients; restrictive threshold (Hb <7.5 g/dL) non-inferior to liberal (<9.5 ICU / <8.5 ward) for death, MI, stroke and new dialysis; fewer transfusions.
- 2023 ACC/AHA AF guideline: post-operative AF after cardiac surgery is common, associated with stroke and mortality; beta-blockers for prevention, amiodarone prophylaxis in high-risk patients, and anticoagulation considered for persistent POAF when bleeding risk allows.
- EACTS/EACTA/EBCP CPB guideline 2019: management of bypass-related physiology including vasoplegia.
Controversies
- Routine PA catheter use (declining; echo increasingly preferred).
- Levosimendan in LCOS (LEVO-CTS, LICORN, CHEETAH trials were neutral).
- Early vs delayed anticoagulation for POAF after cardiac surgery.
- Methylene blue for vasoplegia — signal of benefit in observational data only.
🇮🇳 India notes
- India performs a very large volume of CABG (many off-pump) with shorter ICU stays; off-pump patients have less vasoplegia and bleeding but similar AF.
- Rheumatic heart disease remains a major indication for valve surgery in India: mitral stenosis/regurgitation with pulmonary hypertension and AF, often young patients; mechanical valves with warfarin are common, so INR monitoring access and adherence counselling matter.
- G6PD deficiency prevalence is significant in parts of India — methylene blue can cause severe haemolysis; check status where possible.
- Government schemes (PM-JAY and state schemes) cover many cardiac surgeries; ICU resources may be stretched, making early extubation and fast-track protocols important.
References
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Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.