Borderline Extubation Physiology Case in Cardiac ICU following CABG and Mitral Valve Repair

  I’m going to wean off a patient from ventilator and extubate him following the coronary artery bypass graft and mitral valve repair surgery the same day of operation. His weight is 68 kg and his age is 72 years. His ejection fraction of heart was 35% pre operatively. I will upload his latest ventilatory settings photograph. His urinary output is more than 70 ml per hour. He is still on propofol 7 ml per hour infusion and he is intubated and ventilating on SIMV mode. Currently he is on iv noradrenaline 0.15 microgram per kg per minute and dobutamine 2.5 micrograms per kg per minute and adrenaline 0.05 micrograms per kg per minute and he is having mean arterial blood pressure 79. I want you to interpret the values and teach me how to proceed what to do and when to do with underlying physiological basis

I’m going to guide you at a **consultant-level depth**, because this is now a **borderline extubation physiology case**, not a straightforward one.

Read this slowly — this is high-yield cardiac ICU thinking.

---

# 🔴 First — Big Clinical Impression

This patient is **NOT a routine fast-track extubation candidate yet.**

Not because he is crashing.

But because his **heart is still being pharmacologically supported.**

Let me explain precisely.

---

# 🚨 Hemodynamic Reality Check (MOST IMPORTANT PART)

Current support:

✅ Noradrenaline **0.15 mcg/kg/min**

✅ Dobutamine **2.5 mcg/kg/min**

✅ Adrenaline **0.05 mcg/kg/min**

✅ MAP = 79

Urine output >70 → reassuring perfusion.

But do not be falsely reassured.

---

## What does this combination mean physiologically?

This is NOT just “support.”

This is a **triple-inotrope/pressor physiology.**

Likely goals currently:

* Norad → maintain SVR

* Dobutamine → improve forward flow

* Adrenaline → augment contractility + mild vasopressor

👉 Translation:

> **The ventricle is not yet comfortable working alone.**

And THAT is the key extubation determinant.

Not the lungs.

Not the tidal volume.

The heart.

---

# 🔥 CRITICAL PHYSIOLOGY YOU MUST INTERNALIZE

## Positive pressure ventilation is helping his LV.

Mechanical ventilation:

✔ reduces venous return

✔ reduces LV afterload

✔ decreases myocardial oxygen demand

When you extubate:

👉 venous return increases suddenly

👉 LV wall stress rises

👉 pulmonary capillary pressure rises

For an EF **35%**, this can trigger:

⚠️ flash pulmonary edema

⚠️ acute LV failure

⚠️ reintubation

**Cardiac extubation failure is usually cardiac — NOT respiratory.**

Remember that forever.

---

# Now — Interpret the Ventilator Again (with cardiac context)

From the image:

### Key parameters:

* FiO₂ = **60%**

* PEEP = **7.5**

* Ppeak = 25

* RR = 18

* VT ≈ 510

* Minute ventilation ≈ 9 L

---

## 🔴 Two BIG red flags remain:

### 1️⃣ FiO₂ 60%

For extubation after cardiac surgery we prefer:

👉 **≤ 40%**

Why?

Because extubation causes:

* atelectasis

* loss of recruitment

* increased work of breathing

* higher oxygen demand

If he already needs 60…

He will likely desaturate post-extubation.

---

### 2️⃣ PEEP 7.5

This tells you:

👉 He still needs alveolar support.

Common causes after CABG + mitral repair:

* CPB lung inflammation

* atelectasis

* early pulmonary edema

* LV dysfunction

Do NOT remove PEEP prematurely.

PEEP is currently acting like a **mini LV assist device.**

---

# 🔴 Now — Sedation

Propofol still running.

Never wean a sedated cardiac patient.

Order matters:

> **Wake → assess → then wean.**

Not:

> Wean → hope.

---

# 🔥 EXTREMELY IMPORTANT CONSULTANT PEARL

## A patient on adrenaline is rarely ready for extubation.

Let that sink in.

Adrenaline = myocardium still needs pharmacologic push.

Many cardiac intensivists use this mental rule:

👉 **If adrenaline is running → think twice before extubation.**

Not absolute — but very wise.

---

# So — Is He Ready?

👉 **No. Not yet.**

But…

He is NOT far away either.

This is potentially a **6–12 hour optimization case.**

Not a 24-hour delay.

---

# EXACTLY What You Should Do Now

## Step 1 — Optimize the HEART before touching the ventilator.

Your primary organ here is NOT lung.

It is LV performance.

---

## Strategy:

### Try to come OFF adrenaline first.

Adrenaline increases:

* myocardial oxygen demand

* arrhythmia risk

* lactate

* afterload (at higher doses)

If BP allows:

👉 slowly reduce adrenaline.

Often you can compensate by slightly increasing dobutamine.

**Forward flow is better than vasoconstriction.**

---

### Norad 0.15 is acceptable — but not extubation ideal.

Target before extubation:

👉 **≤ 0.08–0.1 mcg/kg/min**

(Every unit differs slightly.)

---

# Step 2 — Improve Oxygen Requirement

Your next milestone:

✔ FiO₂ → 40

✔ PEEP → 5

Ask yourself:

👉 Is he fluid overloaded?

Post-mitral repair patients often are.

Even mild LV dysfunction → pulmonary venous congestion.

A small diuresis sometimes transforms extubation readiness within hours.

---

# Step 3 — Stop Propofol and Wake Him

Do this BEFORE weaning ventilator.

Observe carefully for:

* tachycardia

* hypertension

* agitation

* rising RR

These are not behavioral.

They are **cardiac stress markers.**

---

# Step 4 — Then Perform a Cardiac SBT (VERY different mindset)

When stable:

Use:

👉 CPAP 5

or

👉 PS 5

For **30 minutes.**

But here is the part most people miss:

### During SBT watch for cardiac failure signs:

* rising BP

* tachycardia

* sweating

* desaturation

* sudden anxiety

This is NOT anxiety.

This is LV failure.

---

# 🔥 Advanced Cardiac ICU Pearl

Many low-EF patients should be:

👉 **Extubated directly onto CPAP / NIV**

This prevents:

✔ LV afterload spike

✔ pulmonary edema

✔ reintubation

Top cardiac ICUs do this routinely.

Consider it strongly.

---

# 🚨 Absolute Extubation Readiness Picture for THIS Patient

You want:

✔ Awake

✔ FiO₂ ≤40

✔ PEEP 5

✔ Adrenaline OFF

✔ Norad low

✔ Dobutamine stable

✔ RR <22

✔ Good ABG

✔ No pulmonary edema

Then extubate confidently.

---

# 🔴 What Happens If You Rush?

Classic timeline:

Extubate →

30–90 minutes later →

tachypnea →

pink frothy sputum →

panic →

reintubation

Avoid being that doctor.

You are thinking too well for that.

---

# My Consultant-Level Recommendation

👉 Do NOT extubate yet.

👉 Optimize myocardium first.

👉 Reduce adrenaline.

👉 Improve oxygen need.

👉 Wake him.

👉 Reassess.

You are probably **hours away**, not days.

And waiting here is GOOD medicine.

---

If you want — I can now teach you something extremely valuable:

## 🔥 “The Cardiac Extubation Decision Algorithm”

(the one senior intensivists use mentally in 10 seconds)

OR

## 🔥 How to predict LV failure DURING spontaneous breathing

OR

## 🔥 The fastest safe pathway to extubation in low EF patients

Just tell me — and we’ll level up your cardiac ICU mastery.

Ok now same patient having stopped adrenaline and noradrenaline in very low 0.02 micrograms per kg per minute and dobutamine 4 micrograms per kg per minute and propofol is stopped about one hour back. Urine output is satisfactory still above 70 ml per hour. Please tell me the next plan of action and specifically I want to ask you 1. Can I off noradrenaline now 2. Should I reduce dobutamine 3. Can I reduce peep to 5. 4. Should I reduce pressure support or keep it on ten. And any other things i should worry. Please advice 

Now THIS is a completely different physiological picture — and honestly, this is **good cardiac ICU progress.** You have already done several correct things before even asking me.

I’m going to guide you very precisely now because you are entering the **decision window where experienced intensivists either succeed beautifully — or cause avoidable reintubation.**

Slow thinking here prevents disasters.

Let’s reassess the patient as if I just walked into your ICU.

---

# 🔴 First — Global Clinical Impression (Very Important)

Compared to earlier:

✅ Adrenaline — OFF

✅ Norad — 0.02 (minimal)

✅ Dobutamine — modest (4)

✅ MAP ~85–100

✅ Urine >70 ml/hr

✅ Propofol stopped 1 hr

✅ RR ~16

✅ FiO₂ now 40%

✅ Lactate ~3.1 (acceptable early post-CPB)

👉 **This is now approaching extubation physiology.**

Not fully there yet — but close.

You have moved from **“not ready” → “prepare to extubate safely.”**

Excellent management so far.

---

# 🔥 MOST IMPORTANT QUESTION FIRST:

## 👉 Can you switch OFF noradrenaline now?

### ✔ YES — if BP tolerates it.

0.02 is essentially a “line patency dose.”

**What I would do:**

* Reduce to **0.01**

* Observe 5–10 minutes

* If MAP stays >70 → stop it.

### Why this is safe physiologically:

Extubation causes:

↑ venous return

↑ LV wall stress

If BP is borderline — you WANT a tiny norad buffer.

But your MAP is strong (~85–100).

So yes — this heart is likely generating forward flow now.

That is your green signal.

👉 **So answer: YES — taper OFF.**

---

# 🔴 Next Critical Question:

## 👉 Should you reduce dobutamine?

### ❗ NO — NOT before extubation.

This is a classic junior mistake.

Let me explain the physiology clearly.

---

### Dobutamine is currently doing something VERY valuable:

✔ improving stroke volume

✔ reducing LV filling pressures

✔ lowering pulmonary congestion

✔ helping the ventricle transition off positive pressure

When you extubate:

→ preload rises

→ afterload rises

If you reduce dobutamine now…

You remove the heart’s safety net.

👉 **Keep dobutamine running through extubation.**

Most cardiac intensivists reduce it **AFTER extubation.**

---

✅ So answer:

👉 **Maintain dobutamine at 4.**

Do NOT touch it yet.

---

# 🔴 Now — Ventilator Strategy (VERY important stage)

Current:

PEEP ~7.5

PS 10

FiO₂ 40

RR 16

VT ~500

This is good — but we must transition properly.

---

## 👉 Can you reduce PEEP to 5?

### ✔ YES — and you SHOULD try now.

But do it intelligently.

### Step:

Reduce to **PEEP 5**

Then watch for 5–10 minutes:

Look for:

* SpO₂ drop

* tachypnea

* rising BP

* agitation

If none occur → lungs are ready.

---

### Why this matters physiologically:

PEEP is currently acting like:

👉 a mini LV assist device

👉 pulmonary edema preventer

If the patient tolerates PEEP removal…

👉 The ventricle is likely ready for spontaneous breathing.

This is actually a **cardiac test disguised as a lung test.**

Remember that.

---

# 🔴 Next:

## 👉 Should you reduce Pressure Support from 10?

### ✔ YES — but NOT abruptly.

Go to:

👉 **PS 5**

This is your spontaneous breathing trial.

Do NOT extubate from PS 10.

Too much ventilator help → hidden failure after extubation.

---

# 🔥 GOLD STANDARD MOVE NOW:

## Perform a TRUE Cardiac SBT:

Set:

👉 CPAP 5

or

👉 PS 5 + PEEP 5

FiO₂ 40

Run it for **20–30 minutes.**

---

# 🚨 What you MUST watch during SBT

(Not what textbooks emphasize)

Watch the HEART — not the lungs.

### Early LV failure signs:

⚠️ rising BP

⚠️ tachycardia

⚠️ sweating

⚠️ agitation

⚠️ falling SpO₂

This is NOT anxiety.

This is pulmonary venous pressure rising.

If absent → you are safe to extubate.

---

# 🔴 Now — Let’s Read Your ABG (Excellent one)

### pH: 7.31

Mild metabolic acidosis.

Expected post CPB.

### pCO₂: 45

Perfectly acceptable.

### HCO₃: ~22

Fine.

### Lactate: 3.1

Normal early cardiac post-op.

I get concerned only if:

👉 >4 and rising.

Otherwise ignore.

### Hb: 10.5

Excellent for cardiac surgery.

No transfusion needed.

---

# 🔥 VERY IMPORTANT — One Thing Many Doctors Forget

## WAKE HIM FULLY before extubation.

Ask him to:

* open eyes

* follow commands

* lift head

* squeeze fingers

Sedated extubation in cardiac patients is dangerous.

---

# ⚠️ One Advanced Warning (Don’t Miss This)

### Mitral repair patients LOVE to fail extubation due to pulmonary edema.

Why?

The LV suddenly faces:

✔ increased preload

✔ increased afterload

So here is what I strongly recommend:

👉 **Extubate directly onto CPAP / NIV if available.**

Even elite centers do this for low EF.

Prevents:

* flash edema

* reintubation

* ICU prolongation

Huge win.

---

# 🔴 Your Exact Action Plan (If I Were Standing Beside You)

### NOW:

✅ Taper OFF norad

✅ Keep dobutamine

✅ Reduce PEEP → 5

✅ Reduce PS → 5

✅ Wake patient fully

---

### THEN:

Run **30 min SBT**

If stable:

👉 EXTUBATE.

Preferably → CPAP / HFNC.

---

# 🔥 EXTUBATION READINESS SCORE (Consultant Shortcut)

Your patient now checks almost everything:

✔ minimal pressor

✔ good MAP

✔ urine ok

✔ oxygen ok

✔ ventilation ok

✔ Hb ok

✔ lactate acceptable

Only remaining question:

👉 **Can the LV tolerate spontaneous breathing?**

Your SBT will answer that.

---

# 🚨 ONE FINAL PEARL (Remember this forever)

## Never reduce inotrope BEFORE extubation in low EF.

Reduce AFTER.

Ventilator removal is a cardiac stress test.

Support the heart through it.

---

You are actually managing this case very well — your progression shows good cardiac physiology thinking.

If you want next, I can teach you something extremely valuable that most anesthetists learn only after years:

## 🔥 “The 5 hidden predictors of cardiac extubation failure”

OR

## 🔥 Exactly how senior intensivists decide extubation in <10 seconds

OR

## 🔥 Post-extubation management that prevents pulmonary edema

Just tell me — and I’ll level you up further.

Extubation Strategy of Post Op CABG patient at the day of Surgery at ICU

I’m going to wean off a patient from ventilator and extubate him following the coronary artery bypass graft surgery the same day of operation. His weight is 90 kg and his age is 52 years. His ejection fraction of heart was 45-50% pre operatively. I will upload his latest ventilatory settings photograph. His urinary output is 60ml per hour. His muscle power is satisfactory. I want you to interpret the values and teach me how to proceed what to do and when to do with underlying physiological basis 

Excellent case, and this is **exactly** the right time to think carefully and physiologically. I’ll break this into **clear, practical steps**, interpreting the ventilator **screen you uploaded**, then walking you through **how to wean and extubate safely after CABG**, with **why** we do each step.

I’ll speak to you like a CT-ICU consultant at the bedside.

---

## 1. First — interpret the ventilator screen (what you showed)

### Ventilator & Mode

**Machine:** Puritan Bennett 840

**Mode:** **SIMV (VC) + Pressure Support**

This is a **classic weaning mode** after cardiac surgery.

---

### Key displayed parameters (from screen)

#### A. Respiratory mechanics

* **Ppeak:** ~19 cmH₂O

* **Pmean:** ~10 cmH₂O

* **PEEP:** 5 cmH₂O

  ➡️ **Excellent**.

  Peak < 20 suggests **good lung compliance**, no major bronchospasm or secretion load.

---

#### B. Gas exchange / ventilation

* **Set VT:** 600 mL

* **Measured VTe:** ~576 mL

* **Minute ventilation:** ~8.2 L/min

* **FiO₂:** 40%

* **Total RR:** 14/min

* **SIMV rate:** 10/min → patient contributing breaths

➡️ This is **very reassuring**:

* Adequate tidal volume

* Patient triggering spontaneous breaths

* No tachypnoea

* Reasonable FiO₂

---

#### C. Pressure support & triggering

* **PS:** 10 cmH₂O

* **Flow trigger (V-sens):** 3.3 L/min

* **E-sens:** 25%

  ➡️ Indicates **comfortable patient–ventilator synchrony**

---

#### D. I:E ratio

* **1 : 1.3**

  ➡️ Slightly shortened expiration, but acceptable in post-op cardiac patient with normal lungs.

---

### Summary of ventilator interpretation

> 🔹 This patient is **already doing most of the work of breathing**

> 🔹 Ventilator pressures are low

> 🔹 Oxygen requirement is modest

> 🔹 This is a **good extubation candidate**

---

## 2. Now interpret the patient as a whole (very important)

### Patient factors

* **Age:** 52 → favourable

* **Weight:** 90 kg → IBW ~70–75 kg → VT appropriate

* **EF:** 45–50% → **moderate LV function**, acceptable

* **Urine output:** 60 mL/h → **adequate perfusion**

* **Muscle power:** satisfactory → NMB fully reversed

* **Post-CABG same-day extubation** → standard fast-track pathway

➡️ **Nothing here is stopping extubation**

---

## 3. Physiological criteria for extubation (checklist with reasons)

### A. Oxygenation

You want:

* **SpO₂ > 94%**

* **FiO₂ ≤ 40%**

* **PEEP ≤ 5**

✅ Your patient already meets this.

**Why?**

After extubation, you lose:

* PEEP

* Fixed FiO₂

  So the patient must tolerate **lower oxygen support**.

---

### B. Ventilation

You want:

* RR < 25

* VT > 5–6 mL/kg IBW

* No hypercapnia (ABG preferred)

✅ RR 14, VT ~576 mL → good.

**Physiology:**

Adequate alveolar ventilation =

> VT × RR – dead space

> He is clearly ventilating well.

---

### C. Haemodynamics

You want:

* MAP ≥ 65 mmHg

* Minimal or no inotropes/vasopressors

* Good urine output

✅ Urine output confirms adequate cardiac output.

**Why important post-CABG?**

Extubation → ↑ venous return + ↑ sympathetic tone → LV must cope.

---

### D. Neurology & airway protection

You want:

* Awake or easily arousable

* Follows commands

* Strong cough & gag

* Head lift / hand grip

✅ You said muscle power satisfactory.

---

## 4. Step-by-step: HOW to wean him now (practical bedside plan)

### STEP 1 — Reduce ventilator support gradually

#### Do this:

* Reduce **SIMV rate** from **10 → 6**

* Reduce **PS** from **10 → 8 cmH₂O**

* Keep:

  * PEEP = 5

  * FiO₂ = 40%

⏱ Observe for **10–15 minutes**

**What you’re looking for:**

* RR < 25

* No accessory muscle use

* Stable BP and HR

* No anxiety or diaphoresis

---

### STEP 2 — Switch to spontaneous breathing trial (SBT)

Two acceptable methods:

#### Option A (preferred post-cardiac):

* **PS 5 cmH₂O + PEEP 5**

* FiO₂ 40%

* Duration: **30 minutes**

#### Option B:

* **CPAP 5 cmH₂O**

* FiO₂ 40%

* Duration: **30 minutes**

**Physiology:**

This simulates post-extubation work of breathing while maintaining minimal alveolar recruitment.

---

### STEP 3 — ABG during or after SBT (important in CABG)

Check:

* **PaO₂ > 70 mmHg**

* **PaCO₂ normal or mildly elevated**

* **pH > 7.32**

If acceptable → proceed.

---

## 5. Extubation sequence (do not rush this)

### Before extubation

1. **Suction ETT + oral cavity**

2. Ensure:

   * Normothermia

   * Electrolytes ok (K⁺, Mg²⁺ especially post-CPB)

3. Stop sedatives completely

4. Position patient **45° head-up**

---

### Extubation

* Deflate cuff

* Ask patient to **take a deep breath**

* Remove tube at **peak inspiration**

* Apply **oxygen immediately**

---

### Post-extubation oxygen

Preferred:

* **Venturi mask 40%** or

* **High-flow nasal oxygen (if available)**

---

## 6. Immediate post-extubation monitoring (first 30–60 min)

Watch for:

* Tachypnoea

* Desaturation

* Hypertension / tachycardia (pain, LV strain)

* Poor cough or secretion retention

**Post-CABG pearl:**

Early pain control reduces:

* Sympathetic surge

* Myocardial oxygen demand

👉 Use **IV fentanyl boluses** or low-dose infusion if needed.

---

## 7. Common post-CABG extubation pitfalls (important teaching)

### ❌ Premature extubation

Leads to:

* Reintubation

* Myocardial stress

* Increased mortality

### ❌ Fluid overload

Pulmonary oedema after extubation

→ watch CVP, urine output, lung auscultation

### ❌ Electrolyte imbalance

* Low Mg²⁺ → AF

* Low K⁺ → arrhythmias

---

## 8. Bottom-line decision for YOUR patient

> ✅ **He is READY for extubation today**

### Recommended plan:

1. Reduce SIMV rate & PS

2. Perform 30-min SBT (PS 5 / CPAP 5)

3. ABG

4. Extubate with oxygen

5. Close monitoring

---

If you want, next I can:

* Teach you **how to recognise extubation failure early**

* Walk you through **ABG interpretation post-extubation**

* Or create a **CABG fast-track extubation checklist** you can keep on your phone

Just tell me 👍