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🫁 Mechanical Ventilation — Mukammal Rahnuma (Complete Guide)

Yaad rakho: Ventilator sirf "numbers set karna" nahi — yeh patient ki physiology ke saath mila ke chalaana hai. — Roberts and Hedges' Clinical Procedures in Emergency Medicine

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🔬 BASIC PHYSIOLOGY — Bunyadi Samajh

Minute Volume (V̇E)

V̇E = VT × Respiratory Rate (f)
Normal = 7–10 L/min

• VT (Tidal Volume) = Alveolar Volume + Dead Space Volume
• Alveolar Ventilation (V̇A) = (VT − VDS) × f
• V̇A hi CO₂ remove karta hai — isliye rate aur VT dono CO₂ control karte hain

Compliance aur Pressure

P = V ÷ C

• Stiff lungs (↓compliance) = same volume ke liye zyada pressure chahiye
• ARDS mein compliance bahut kam hoti hai → lung injury ka risk zyada

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👤 1. Patient-Specific Factors — Har Mareed Alag Hai

Predicted Body Weight (PBW):

• Male: 50 + 2.3 × (height in inches − 60)
• Female: 45.5 + 2.3 × (height in inches − 60)

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💨 2. Tidal Volume (VT) — Kitni Hawa Deni Hai?

Standard Setting

ARDS Network (NIH) Trial: 861 patients — VT 6 mL/kg ne mortality 40% → 31% kar di. Yeh landmark evidence hai. — Fishman's Pulmonary Diseases and Disorders

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⚙️ 3. Ventilator Mode Selection — Kaun Sa Mode Kab?

Main Modes:

🔹 Volume-Controlled (VC / AC — Assist Control)

• Set: VT, Rate, FiO₂, PEEP, Inspiratory Flow Rate
• Machine ek fixed volume deliver karta hai — pressure variable hoti hai
• Use karein: Sedated/paralyzed patients, ARDS
• ⚠️ Disadvantage: Zyada sedation chahiye, patient-ventilator dyssynchrony ka risk

🔹 Pressure-Controlled (PCV)

• Set: Pressure, Rate, TI, FiO₂, PEEP
• Machine ek fixed pressure deliver karta hai — volume variable hoti hai
• Use karein: Stiff lungs, barotrauma risk ho

🔹 Pressure Support Ventilation (PSV)

• Patient khud breath trigger karta hai, machine support deti hai
• Use karein: Weaning ke liye, spontaneous breathing wale patients
• ⚠️ Agar patient effort nahi karta → apnea alarm

🔹 SIMV (Synchronized Intermittent Mandatory Ventilation)

• Set rate + patient ki spontaneous breaths dono hoti hain
• Use karein: Surgical/neurosurgical patients, gradual weaning
• ⚠️ Weaning outcomes sabse kharab SIMV mein hain

🔹 APRV (Airway Pressure Release Ventilation) / BiLevel

• Time High (4–6 sec): High pressure → oxygenation
• Time Low (0.2–0.8 sec): Pressure release → CO₂ clearance
• Use karein: Severe ARDS, recruitment chahiye ho, sedation kam karni ho
• Patient har phase mein spontaneously breathe kar sakta hai

🔹 PRVC / VC+ / Adaptive Pressure Ventilation

• Volume guarantee karta hai, but pressure variable rakhta hai
• "Best of both worlds" — volume safety + pressure comfort
• — Roberts and Hedges' Clinical Procedures in Emergency Medicine

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🩸 4. Oxygenation Parameters — SpO₂ aur PaO₂

Target:

FiO₂ / PEEP Table (ARDS Network):

Jab FiO₂ badhao, PEEP bhi saath badhao — ye table guide karta hai. — Fishman's Pulmonary Diseases and Disorders

PEEP Optimize Karna:

• Optimal PEEP = woh level jahan plateau pressure increment karna band ho jaye
• Open Lung Model: PV loop straight upstroke → alveoli khuli hain
• Flat lower limb on PV loop = inadequate PEEP → alveoli collapse ho rahi hain

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💨 5. Ventilation (CO₂ Removal) — PaCO₂ Control

PaCO₂ ↑ → Rate ya VT badhao (Minute Ventilation ↑)
PaCO₂ ↓ → Rate ya VT ghataoo

ARDS Network: Rate 6–35 set kar sakte hain, adjust karo arterial pH ≥7.30 achieve karne ke liye — Fishman's Pulmonary Diseases and Disorders

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📊 6. Airway Pressures — Pressure Monitor Karo!

Auto-PEEP kaise banta hai?

• Expiration puri nahi hoti before next breath
• Flow-time curve pe: Flow zero nahi hota — air trapping
• Fix: Rate ghataoo, Expiratory time (TE) badhao, bronchodilators deo

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😷 7. Kaun Sa Mask Use Karna Hai? (NIV Masks)

NPPV (Non-Invasive Positive Pressure Ventilation) — Kab?

• Haan karein: COPD exacerbation, cardiogenic pulmonary edema, obese hypoventilation
• Nahi karein: Unconscious, vomiting risk, cannot protect airway, hemodynamically unstable
• 1–2 ghante mein improvement nahi → intubate karo

— Roberts and Hedges' Clinical Procedures in Emergency Medicine

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🔄 8. Patient–Ventilator Synchrony — "Fighting the Ventilator"

Types of Dyssynchrony:

Dyssynchrony ka Management:

1. Sedation + Analgesia — pehli line
2. Neuromuscular Blockade (NMB) — severe ARDS mein

• Propofol: 5–80 μg/kg/min
• Dexmedetomidine: 0.2–1.5 μg/kg/hr
• Midazolam: 1–6 mg IV PRN
• Lorazepam: 1–5 mg IV PRN

• Fentanyl (first choice — hemodynamically stable)
• Morphine (caution in renal failure)
• Remifentanil infusion: 0.025–0.2 μg/kg/hr

• Vecuronium: 0.1 mg/kg IV bolus (intermediate duration, safe in CVD)
• Pancuronium: alternative
• ⚠️ NMBAs mein sedation ZAROOR deo — inhe koi analgesia ya amnesia nahi milti

— Roberts and Hedges' Clinical Procedures in Emergency Medicine

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⚠️ 9. Complications to Watch — Kya Dekho?

DOPE Mnemonic (Sudden Deterioration):

Common Complications:

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📈 10. Monitoring — Kya Track Karna Hai?

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🏥 11. ARDS — Step-by-Step Management

Berlin Definition:

Step 1 — Lung Protective Strategy (MANDATORY)

VT = ≤6 mL/kg PBW
Plateau Pressure = ≤30 cm H₂O
PEEP = Table se titrate karo
Mode = Volume Assist-Control
Rate = 6–35, pH ≥7.30 target
FiO₂/PEEP = ARDS Network table follow karo

Step 2 — Pressure Changes Analyze Karo

Step 3 — ABG-Based Adjustments

pH <7.20 → RR max 35, VT 7 mL/kg tak temporarily allow
PaO₂ <55 → FiO₂ ↑ + PEEP ↑ (table se)
PaO₂ >80 → FiO₂ ↓ pehle, phir PEEP ↓

1. Prone Positioning — 16+ hrs/day (severe ARDS mein mortality ↓)
2. Neuromuscular Blockade — Cisatracurium 48h (moderate-severe ARDS)
3. Inhaled NO — temporary bridge
4. ECMO (VV-ECMO) — last resort, P-SILI prevent karna

Step 4 — Emergency Drug Support

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🔚 12. Weaning Readiness — Kab Ventilator Se Nikaalna?

Criteria (SAT + SBT):

• ✅ Underlying cause improving
• ✅ FiO₂ ≤ 0.4–0.5, PEEP ≤ 5–8
• ✅ SpO₂ >90% on above settings
• ✅ Patient awake, follows commands
• ✅ Hemodynamically stable (vasopressors minimal/off)
• ✅ Adequate cough/gag reflex

Spontaneous Breathing Trial (SBT):

Post-Extubation:

• COPD: NPPV → mortality ↓, HAP ↓
• Hypoxia risk: HFNC → reintubation ↓ in low-risk patients
• HFNC vs NPPV: dono similar outcomes post-extubation

Failure to Wean — Kyun?

— Washington Manual of Medical Therapeutics

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🎯 Quick Reference Card

ARDS VENTILATOR SETTINGS (ARDS Network):
─────────────────────────────────────────
Mode:          Volume Assist-Control
VT:            ≤6 mL/kg PBW
Plateau:       ≤30 cm H₂O
Rate:          6–35 (pH ≥7.30 target)
FiO₂:          Table se titrate
PEEP:          Table se titrate
SpO₂ target:   88–95%
PaO₂ target:   55–80 mmHg
I:E ratio:     1:1 to 1:3

SUDDEN DETERIORATION → DOPE
D = Dislodgment
O = Obstruction
P = Pneumothorax
E = Equipment
→ Bag + 100% O₂ foran!

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• Roberts and Hedges' Clinical Procedures in Emergency Medicine
• Fishman's Pulmonary Diseases and Disorders (2-Volume Set)
• Washington Manual of Medical Therapeutics
• Murray & Nadel's Textbook of Respiratory Medicine
• Harrison's Principles of Internal Medicine 22E

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🫁 50 VENTILATOR CLINICAL CASES

ICU / Emergency Medicine — Detailed Management Guide

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📌 CATEGORY 1: ARDS (Cases 1–12)

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🔴 CASE 1 — Classic Severe ARDS (Sepsis-Induced)

Mode:     Volume AC (Assist-Control)
VT:       6 mL/kg PBW (PBW = 70 kg → VT = 420 mL)
Rate:     22/min
FiO₂:     1.0 (100%)
PEEP:     14 cm H₂O (high PEEP per ARDS table)
I:E:      1:2

• pH 7.30, PaO₂ 62, PaCO₂ 48, HCO₃ 23 — improving

• Plateau = 28 cm H₂O ✅ (< 30)
• Peak = 38 cm H₂O → Peak − Plateau = 10 (airway resistance component)

1. Prone positioning 16 hrs/day (severe ARDS)
2. Cisatracurium 15 mg IV bolus → 37.5 mg/hr infusion × 48h
3. Conservative fluid strategy
4. Norepinephrine 0.2 μg/kg/min for MAP ≥65
5. Daily FiO₂ wean — PEEP table follow karo
6. VAP bundle: HOB 30–45°, oral chlorhexidine, daily SBT screen

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🔴 CASE 2 — Moderate ARDS + High Plateau (Overdistension Risk)

↓ VT: 550 → 480 → 420 mL (6 mL/kg)
↑ RR: 16 → 22 (compensate minute ventilation)
PEEP: ↑ to 10 per table
FiO₂: 0.6 maintain karein

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🔴 CASE 3 — ARDS + Permissive Hypercapnia

Accept pH ≥7.20 — safe range
Sodium Bicarbonate AVOID (CO₂ produce karta hai)
Rate: max 35/min try karo
Monitor: cardiac arrhythmia, ICP (agar brain injury ho)

— Fishman's Pulmonary Diseases and Disorders

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🔴 CASE 4 — ARDS + Auto-PEEP

↓ Respiratory Rate: 22 → 14
↑ Expiratory Time (↓ I:E from 1:2 to 1:3)
Bronchodilator: Salbutamol neb q4h + Ipratropium
↓ Set PEEP: 10 → 8
Fluid bolus if hypotension persists

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🔴 CASE 5 — ARDS + Prone Position Management

Duration: 16 hrs prone, 8 hrs supine
Position: Head neutral, arms "swimmer position"
ETT: Confirm position before turning
Eyes: Pad/protect
Pressure points: Forehead, chest, knees pad karo
Lines/tubes: All secure karo before turning

• PaO₂: 48 → 85 mmHg ✅
• PaO₂/FiO₂: 72 → 170 (significant improvement)

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🔴 CASE 6 — ARDS + Refractory Hypoxia (VV-ECMO Candidate)

FiO₂: 1.0, PEEP: 18, VT 6 mL/kg
Prone: done × 3 cycles
iNO: tried — minimal response
PaO₂/FiO₂: 58
Plateau: 29

• Murray Score ≥3
• PaO₂/FiO₂ <80 despite optimal vent + prone
• Age <65, no contraindication

• Femoral vein drainage (21–25 Fr) → Internal jugular return (15–19 Fr)
• Flow: 3–5 L/min
• Ventilator: "Rest settings" — FiO₂ 0.4, PEEP 10, RR 10, VT 3–4 mL/kg
• Goal: Lung rest while ECMO does gas exchange

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🔴 CASE 7 — Mild ARDS, NIV Trial

IPAP: 14 cm H₂O
EPAP: 8 cm H₂O
FiO₂: 0.6

• SpO₂ >92%, RR <25, HR <110, no worsening confusion

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🔴 CASE 8 — ARDS + Pneumothorax (Sudden Deterioration)

• D: ETT position check — OK
• O: Suction catheter passes easily — OK
• P: ↓ breath sounds right, trachea deviated left, ↑ resonance right → TENSION PNEUMOTHORAX
• E: Equipment check — OK

1. Disconnect ventilator → Bag + 100% O₂
2. Needle decompression: 2nd ICS, MCL, right side → immediate
3. Chest tube: 4th/5th ICS, AAL
4. Reconnect to ventilator
5. ↓ PEEP temporarily (contributed to barotrauma)
6. CXR confirm

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🔴 CASE 9 — ARDS + Dyssynchrony (Double Triggering)

Step 1: Check sedation — Propofol infusion titrate up
Step 2: ↑ Inspiratory Time (Ti) — breaths match patient effort
Step 3: If persists → Cisatracurium (NMB) + confirm sedation adequate
Step 4: Remifentanil infusion: 0.025–0.1 μg/kg/hr add karo

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🔴 CASE 10 — ARDS + Fluid Management

Target: Even to slightly negative fluid balance
Furosemide: 40 mg IV → titrate
Daily weights + strict I&O
Albumin if oncotic pressure low (Albumin <2.5)
Avoid: Unnecessary fluid boluses

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🔴 CASE 11 — ARDS + VAP Development

Empiric: Piperacillin-Tazobactam + Vancomycin (MRSA coverage if risk)
Adjust per cultures (Day 3–5)
Duration: 7 days (uncomplicated)
VAP Bundle reinforce:
  - HOB 30–45°
  - Daily oral chlorhexidine
  - Subglottic secretion drainage
  - Daily SBT screen

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🔴 CASE 12 — ARDS Weaning: When to Start?

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📌 CATEGORY 2: COPD Exacerbation (Cases 13–20)

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🟠 CASE 13 — COPD Acute Exacerbation, NIV Start

IPAP: 14 cm H₂O (start) → titrate to 20 if needed
EPAP: 5 cm H₂O
FiO₂: 0.28–0.35 (Venturi mask target SpO₂ 88–92%)
Backup RR: 12/min

• Salbutamol 2.5 mg neb q20 min × 3
• Ipratropium 0.5 mg neb q6h
• Prednisolone 40 mg PO/IV × 5 days
• Antibiotics: Amoxicillin-Clavulanate (or Doxycycline/Azithromycin)

• pH 7.36, PaCO₂ 58 ↓, SpO₂ 91% ✅ — NIV success

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🟠 CASE 14 — COPD NIV Failure → Intubation

• RSI: Ketamine (1–2 mg/kg) + Succinylcholine preferred
• ETT: Size 8.0+ (allows easier suctioning)

Mode:     Volume AC
VT:       6–8 mL/kg PBW
Rate:     12–14 (LOW — allow expiration)
FiO₂:     0.4–0.5 (SpO₂ 88–92% target)
PEEP:     5 cm H₂O (external PEEP = ~80% auto-PEEP)
I:E:      1:3 to 1:4 (long expiratory time!)
IFR:      High (60–80 L/min) — fast inspiration, long expiration

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🟠 CASE 15 — COPD + Auto-PEEP + Hemodynamic Collapse

Step 1: DISCONNECT ventilator 30–60 sec
         (allows hyperinflated lungs to decompress)
Step 2: Manual compression of chest wall to assist expiration
Step 3: Reconnect — ↓RR, ↑TE, ↓ I:E
Step 4: Fluid bolus 500 mL crystalloid
Step 5: Bronchodilators IV/neb
Step 6: Check for pneumothorax (always rule out)

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🟠 CASE 16 — COPD + Cor Pulmonale on Vent

- Avoid high PEEP (↑ RV afterload)
- PEEP ≤ 5 in severe RV dysfunction
- Target PaCO₂ normal/low (↓ pulmonary vasoconstriction)
- Consider inhaled NO for RV support
- Avoid hypoxia (potent pulmonary vasoconstrictor)
- Norepinephrine for systemic BP (maintains coronary perfusion)
- Avoid vasodilators (worsen V/Q mismatch)

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🟠 CASE 17 — COPD Weaning: Prolonged Difficulty

- SIMV mode: Gradually ↓ set rate over 24–48h
- Nutrition optimization: Enteral feeds, 25–30 kcal/kg/day
- Metabolic alkalosis: Acetazolamide 250 mg BD (↑ respiratory drive)
- Physical therapy: Daily passive/active exercises
- Psychiatric: Treat delirium (Haloperidol or Quetiapine)

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🟠 CASE 18 — COPD + Mucus Plug Obstruction

• D: ETT at 22 cm — OK
• O: Suction catheter blocked at 15 cm → MUCUS PLUG
• P: Bilateral breath sounds present
• E: Equipment OK

1. Suction aggressively (saline flush if needed)
2. Fiberoptic bronchoscopy if suction unsuccessful
3. Chest physiotherapy (vibration, percussion)
4. N-acetylcysteine nebulization (mucolytic)
5. Ensure humidification of vent circuit
6. Adequate hydration

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🟠 CASE 19 — COPD Post-Extubation NIV

BiPAP restart:
IPAP: 16, EPAP: 6, FiO₂ 0.35
Target: SpO₂ 88–92%, RR <25

— Washington Manual of Medical Therapeutics

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🟠 CASE 20 — COPD + Concurrent Pneumonia (CAP)

Mode: Volume AC
VT: 6 mL/kg (treat as ARDS/lung protective)
RR: 16 (balance between CO₂ clearance and air trapping)
PEEP: 8 (modest PEEP for pneumonia + COPD)
FiO₂: 0.6 → wean per SpO₂
Antibiotics: Piperacillin-Tazobactam + Azithromycin

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📌 CATEGORY 3: Asthma / Bronchospasm (Cases 21–24)

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🟡 CASE 21 — Status Asthmaticus → Intubation

Mode:    Volume AC
VT:      6 mL/kg PBW
Rate:    10–12/min (VERY LOW — prevent air trapping)
FiO₂:    1.0 initially
PEEP:    0–5 cm H₂O (low — already auto-PEEP present)
I:E:     1:4 to 1:5 (maximum expiratory time)
IFR:     High: 80 L/min
Plateau: Target <30, but may be elevated initially

• Magnesium sulfate 2g IV over 20 min
• Salbutamol IV infusion 5–20 μg/min
• Methylprednisolone 125 mg IV q6h
• Heliox (70% He/30% O₂) if available

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🟡 CASE 22 — Asthma + Respiratory Arrest (Post-Intubation)

1. Auto-PEEP → obstructive shock
2. Tension pneumothorax
3. Induction agent side effect (propofol → hypotension)

↓ RR: 10 → 8
↑ I:E: 1:4 → 1:5
↓ PEEP: 5 → 3
Fluid bolus 500 mL
Norepinephrine if needed

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🟡 CASE 23 — Asthma + Permissive Hypercapnia

Target pH ≥7.15 (asthma protocol)
Do NOT ↑ RR above 12 — worsens air trapping
Sodium bicarbonate: avoid (worsens CO₂ load)
NaHCO₃ ONLY if pH <7.10 + cardiac instability
Continue aggressive bronchodilators
Monitor: ↓ auto-PEEP = improvement

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🟡 CASE 24 — Asthma Weaning

• Peak pressure decreasing (↓bronchospasm)
• Auto-PEEP ↓ to <5 cm H₂O
• Bronchodilator response on exam

↑ RR gradually (12 → 14 → 16)
Confirm plateau remains <30
Start PSV trial when patient awake + cooperative
SBT → extubate
Post-extubation: Continue inhaled steroids + LABA

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📌 CATEGORY 4: Cardiogenic Pulmonary Edema (Cases 25–28)

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🔵 CASE 25 — Acute Pulmonary Edema (APE), NIV

CPAP: 10 cm H₂O, FiO₂ 0.6
OR BiPAP: IPAP 14, EPAP 8, FiO₂ 0.6

• GTN (nitroglycerin): 0.5 mg sublingual → IV infusion
• Furosemide: 80 mg IV
• Morphine: 2–4 mg IV (reduces preload, anxiolysis)
• Aspirin 300 mg (if ACS trigger)

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🔵 CASE 26 — APE → Intubation (CPAP Failure)

Mode:   Pressure Control
PC:     12 cm H₂O above PEEP
PEEP:   8–10 (reduces preload + improves oxygenation)
Rate:   16
FiO₂:  0.8 → wean
I:E:   1:2

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🔵 CASE 27 — APE + Cardiogenic Shock

Mode: Volume AC
VT: 6–8 mL/kg
PEEP: 8 (careful — reduces preload further)
FiO₂: 1.0

• Dobutamine: 5–10 μg/kg/min (inotrope)
• Norepinephrine: 0.1–0.3 μg/kg/min (vasopressor)
• IABP consider (intra-aortic balloon pump)
• PCI: emergency reperfusion ASAP

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🔵 CASE 28 — APE + Respiratory Alkalosis

↓ RR: 18 → 12
Target PaCO₂: 35–45
Monitor: Alkalosis causes ↓ ionized Ca, arrhythmias, cerebral vasoconstriction

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📌 CATEGORY 5: Pneumonia / Sepsis-Related (Cases 29–32)

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🟢 CASE 29 — Severe CAP (Streptococcal) + Respiratory Failure

Mode: Volume AC
VT: 6 mL/kg
PEEP: 8
FiO₂: 0.5
Rate: 16

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🟢 CASE 30 — HAP/VAP + Worsening Vent Requirements

• Piperacillin-Tazobactam 4.5g IV q8h × 7 days
• De-escalate on Day 3 if improving

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🟢 CASE 31 — Aspiration Pneumonitis → ARDS

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🟢 CASE 32 — Pneumocystis Pneumonia (PCP) + ARDS in HIV

• TMP-SMX: 15–20 mg/kg/day TMP component IV × 21 days
• Prednisolone 40 mg BD (if PaO₂ <70 mmHg) — reduces inflammation, ↓ mortality
• Avoid high PEEP initially (risk of pneumothorax in PCP)

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📌 CATEGORY 6: Neuromuscular / Post-Op / Miscellaneous (Cases 33–42)

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🟣 CASE 33 — Guillain-Barré Syndrome (GBS) + Respiratory Failure

Mode: Volume AC (low RR — no auto-breathing drive issue)
VT: 6 mL/kg
Rate: 12–14
PEEP: 5
FiO₂: 0.4

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🟣 CASE 34 — Myasthenic Crisis

• IVIG 2 g/kg over 2–5 days
• Plasmapheresis (faster than IVIG for crisis)
• IV methylprednisolone (with caution — initial worsening possible)
• Pyridostigmine: HOLD during crisis (increases secretions on vent)

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🟣 CASE 35 — Post-Op (Thoracotomy) Respiratory Failure

VT: 5–6 mL/kg (protect single remaining lung)
PEEP: 5 (cautious — ↑ mediastinal shift risk)
FiO₂: 0.6
Rate: 14
Avoid: Over-aggressive PEEP, large VT

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🟣 CASE 36 — Cervical Spinal Cord Injury (C4 Level)

Mode: AC (may need full control initially)
VT: 6–8 mL/kg
PEEP: 5
FiO₂: 0.4

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🟣 CASE 37 — Severe TBI + ICP Management on Vent

PaCO₂: 35–40 mmHg (NORMAL — not hyperventilate routinely)
PaO₂: >100 mmHg (avoid hypoxia — worsens secondary brain injury)
SpO₂: >95%
PEEP: 5 cm H₂O (higher PEEP ↑ ICP by ↑ CVP)
HOB: 30° (↓ ICP, ↓ VAP)

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🟣 CASE 38 — Drowning + ARDS

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🟣 CASE 39 — Obese Hypoventilation Syndrome (OHS)

BiPAP: IPAP 20, EPAP 10
FiO₂: 0.5
SpO₂ target: 88–92%

VT: Based on IDEAL body weight (NOT actual)
  PBW = 45.5 + 2.3 × (height in inches − 60) [for female]
PEEP: 10–14 (need higher PEEP for obese)
Positioning: 30–45° head up

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🟣 CASE 40 — Pulmonary Embolism + Respiratory Failure

PEEP: LOW (≤5) — high PEEP worsens RV afterload
VT: 6 mL/kg
FiO₂: 1.0 initially
Rate: 14
Avoid: High intrathoracic pressure

• Massive PE: Alteplase 100 mg IV over 2h (thrombolysis)
• Or surgical/catheter embolectomy
• Anticoagulation: Heparin infusion

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🟣 CASE 41 — Anaphylaxis + Airway Obstruction

Epinephrine: 0.5 mg IM (anterolateral thigh)
Intubation: EARLY (airway may close completely)
Video laryngoscopy / surgical airway backup ready
Hydrocortisone 200 mg IV + Chlorphenamine 10 mg IV

Mode: Volume AC
PEEP: 5
FiO₂: 1.0 initially → wean
Bronchodilator if bronchospasm component

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🟣 CASE 42 — Bilateral Lung Transplant (Early Graft Dysfunction)

VT: 6 mL/kg (ultra lung protective)
PEEP: 8–10
FiO₂: 0.6
iNO: 20 ppm (pulmonary vasodilator, reduces PVR)
Avoid: High peak pressures (fresh anastomosis)

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📌 CATEGORY 7: ABG-Based Management (Cases 43–47)

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🔷 CASE 43 — Metabolic Acidosis on Vent (DKA)

• Primary: Metabolic acidosis (low HCO₃)
• Compensation: Respiratory alkalosis (low PaCO₂ = Kussmaul breathing)

Do NOT sedate heavily (suppress Kussmaul breathing)
Rate: Keep high (20–24) to maintain PaCO₂ ~18–20
Primary treatment: Insulin infusion + IV fluids

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🔷 CASE 44 — Respiratory Alkalosis on Vent (Over-ventilation)

↓ RR: Reduce by 2–4 breaths/min
Target PaCO₂: 35–45
Recheck ABG in 30 min

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🔷 CASE 45 — Mixed Disorder: Metabolic Alkalosis + Respiratory Acidosis

• Chronic respiratory acidosis (COPD) → renal compensation → high HCO₃
• Over-diuresed → metabolic alkalosis added

Acetazolamide 250 mg BD IV (↑ bicarb excretion)
Potassium correction (diuresis causes hypokalemia)
Avoid aggressive diuresis
↓ RR slightly to allow CO₂ to normalize

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🔷 CASE 46 — Hypoxemia Despite High FiO₂ (Shunt Physiology)

Recruitment maneuver: Sustained inflation 40 cm H₂O × 40 sec
(Monitor: BP drop expected — have vasopressor ready)
Prone position: Recruits posterior units
PEEP ↑ to 18–20 (per ARDS table)
iNO trial: 20 ppm
If no improvement → VV-ECMO

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🔷 CASE 47 — Normal PaCO₂ but Low pH (Mixed Problem)

• High AG metabolic acidosis (AG 24 − normal 12 = Δ AG 12)
• Delta-delta: (ΔAG / ΔHCO₃) = 12/10 = 1.2 → mixed high AG + normal AG acidosis
• Causes: Lactic acidosis + RTA or diarrhea

Maintain PaCO₂ 35–40 (compensating is not needed — PaCO₂ already normal)
Treat underlying cause (sepsis → lactate)
Sodium bicarb if pH <7.10 + hemodynamic instability

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📌 CATEGORY 8: Weaning & Extubation Challenges (Cases 48–50)

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🟤 CASE 48 — Failed SBT × 3 (Prolonged Mechanical Ventilation)

1. Correct K⁺ → 4.0 mEq/L, Mg → 2.0
2. Enteral nutrition: 30 kcal/kg/day high protein
3. Haloperidol for delirium
4. Furosemide: diurese for diastolic dysfunction
5. Daily ABCDE bundle:
   A - Assess analgesia
   B - SAT (Spontaneous Awakening Trial)
   C - SBT
   D - Delirium screen
   E - Mobility/exercise
6. Tracheostomy (Day 14+) for comfort + weaning

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🟤 CASE 49 — Successful Extubation + HFNC Bridge

• Age 55
• ARDS history
• BMI 32
• On vent >7 days

HFNC settings:
Flow: 40–60 L/min
FiO₂: 0.4
Temperature: 37°C humidified

• RR <25, SpO₂ >93%, no distress → continue HFNC
• If fails → BiPAP or re-intubate

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🟤 CASE 50 — Tracheostomy Patient: Vent Liberation

Phase 1: T-piece trials 1–2h/day
Phase 2: Progressive T-piece (4→8→12h)
Phase 3: Speaking valve (Passy-Muir) — assess phonation, swallow
Phase 4: Trach capping (24h off vent)
Phase 5: Decannulation if criteria met:
  - GCS adequate, cough reflex present
  - Secretions manageable
  - Cap tolerated 24h

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🎯 MASTER SUMMARY TABLE

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Sources: Harrison's Principles of Internal Medicine 22E · Fishman's Pulmonary Diseases & Disorders · Roberts & Hedges' Clinical Procedures in Emergency Medicine · Washington Manual of Medical Therapeutics · Murray & Nadel's Textbook of Respiratory Medicine