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🏥 ICU SURVIVAL GUIDE FOR THE NEWLY JOINED DOCTOR

A Complete Beginner's Reference — Harrison's, Washington Manual, Sabiston, Barash (2024-2025 editions)

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TABLE OF CONTENTS

1. ICU Mindset & Daily Routine
2. Central Venous Pressure (CVP) Line
3. Airway Management & Endotracheal Intubation
4. Rapid Sequence Intubation (RSI) Drugs
5. Mechanical Ventilator & Modes
6. ABG (Arterial Blood Gas) Interpretation
7. Emergency & Common ICU Drugs (Vasopressors, Sedation, Analgesia)
8. Important ICU Tests & Monitoring
9. Key Formulas Cheat Sheet

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1. ICU MINDSET & DAILY ROUTINE

Rule: If you don't know why a line, tube, or drug is there -- find out or remove it.

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2. CENTRAL VENOUS PRESSURE (CVP) LINE

What is a CVP Line?

Indications

• CVP/hemodynamic monitoring
• Vasopressor infusion (noradrenaline, dopamine)
• TPN (total parenteral nutrition)
• Rapid volume resuscitation
• Repeated blood sampling
• When peripheral IV access fails

Sites (Pros & Cons)

CVP Normal Values & Interpretation

CVP Normal:  2 - 8 mmHg  (or  5 - 12 cmH₂O)

CVP LOW (<2 mmHg)      → Hypovolemia → GIVE FLUIDS
CVP HIGH (>12 mmHg)    → Volume overload, RV failure, cardiac tamponade
                         → RESTRICT fluids, look for cause

Procedure Checklist (Before You Insert)

1. Consent & explain to patient/family
2. Position: Trendelenburg (head-down) for IJV/subclavian
3. Full sterile technique: cap, mask, gown, gloves, drape
4. Ultrasound guidance preferred (reduces complications)
5. Confirm position with CXR post-procedure
6. Check for: pneumothorax, malposition, hemothorax

Complications to Watch

• Pneumothorax (get CXR immediately after subclavian/IJV line)
• Arterial puncture (bright red, pulsatile blood)
• Air embolism (Trendelenburg position prevents this)
• CLABSI (central line associated bloodstream infection) - change with strict aseptic technique

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3. AIRWAY MANAGEMENT & ENDOTRACHEAL INTUBATION

When to Intubate? (Indications)

Airway Prep - Before You Touch the Patient

ETT Size Guide

Adult Male:     7.5 - 8.0 mm (insert at 23 cm at lips)
Adult Female:   7.0 - 7.5 mm (insert at 21 cm at lips)
Cuff pressure:  20 - 30 cmH₂O

Sniffing Position

• Neck flexed, head extended -- aligns oral, pharyngeal, and tracheal axes
• Obese patients: ramped position (elevate head/shoulders on blankets)

Confirming ETT Placement

1. Primary: End-tidal CO₂ (ETCO₂) waveform -- gold standard
2. Bilateral chest rise and air entry
3. Fogging of ETT
4. CXR: tip should be 3-5 cm above carina (at level of carina = right mainstem bronchus)
5. SpO₂ maintained

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4. RSI (RAPID SEQUENCE INTUBATION) DRUGS

RSI Drug Table

RSI Quick Algorithm

Pre-oxygenate (3 min 100% O₂ or 8 vital capacity breaths)
        ↓
Induction agent (etomidate 0.3 mg/kg OR ketamine 1.5 mg/kg)
        ↓
Paralytic (succinylcholine 1.5 mg/kg OR rocuronium 1.2 mg/kg)
        ↓
Wait 45-60 sec (fasciculations → relaxation)
        ↓
Laryngoscope → visualize cords → pass ETT
        ↓
Inflate cuff → confirm with ETCO₂ → secure tube
        ↓
Start ventilator

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5. MECHANICAL VENTILATOR & MODES

Basic Ventilator Settings (What You Set)

IBW (Ideal Body Weight): Male: 50 + 2.3 × (height in inches - 60) Female: 45.5 + 2.3 × (height in inches - 60)

Ventilator Modes Chart

Key Ventilator Concepts

PEEP (Positive End-Expiratory Pressure)
→ Keeps alveoli open at end-expiration
→ Prevents atelectasis
→ Improves oxygenation
→ Can decrease venous return (watch BP in hypovolemia!)

Plateau Pressure
→ Measured by inspiratory hold
→ Reflects alveolar pressure (lung compliance)
→ Target: < 30 cmH₂O (lung-protective)
→ High plateau = poor compliance (ARDS, pulmonary edema, pneumothorax)

Driving Pressure = Plateau Pressure - PEEP
→ Target < 15 cmH₂O (associated with better ARDS outcomes)

Auto-PEEP (Breath Stacking)
→ Occurs in obstructive disease (COPD, asthma)
→ Air trapped → intrinsic PEEP builds up
→ Fix: ↓ RR, ↑ expiratory time, bronchodilators

Lung-Protective Ventilation (for ARDS)

Vt = 6 mL/kg IBW (NOT actual body weight)
PEEP = 5-20 cmH₂O (titrate to oxygenation)
Plateau pressure < 30 cmH₂O
FiO₂ titrated to SpO₂ > 88%
Consider prone positioning if P/F ratio < 150

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6. ABG (ARTERIAL BLOOD GAS) INTERPRETATION

Normal ABG Values

6-Step ABG Interpretation Method

STEP 1: Is the pH acidic or alkalotic?
         pH < 7.35 = ACIDEMIA
         pH > 7.45 = ALKALEMIA

STEP 2: What is the primary disorder?
         ┌──────────────────────────────────────────────┐
         │  pH↓ + PaCO₂↑  = Respiratory ACIDOSIS       │
         │  pH↓ + HCO₃↓   = Metabolic ACIDOSIS         │
         │  pH↑ + PaCO₂↓  = Respiratory ALKALOSIS      │
         │  pH↑ + HCO₃↑   = Metabolic ALKALOSIS        │
         └──────────────────────────────────────────────┘

STEP 3: Is there appropriate COMPENSATION?
         Metabolic Acidosis → Winter's Formula:
         Expected PaCO₂ = (1.5 × HCO₃) + 8 ± 2
         
         Metabolic Alkalosis:
         Expected PaCO₂ = 40 + 0.7 × (HCO₃ - 24)
         
         Respiratory Acidosis (Acute): HCO₃ rises 1 per 10 CO₂ rise
         Respiratory Acidosis (Chronic): HCO₃ rises 3.5 per 10 CO₂ rise

STEP 4: Calculate ANION GAP (AG)
         AG = Na⁺ - (Cl⁻ + HCO₃⁻)
         Normal AG = 8-12 mEq/L (or up to 12 if albumin-corrected)
         
         Correct for Albumin:
         Corrected AG = Measured AG + 2.5 × (4 - serum albumin)

STEP 5: If AG is elevated, find the cause (MUDPILES)
         M - Methanol
         U - Uremia
         D - DKA / starvation ketosis
         P - Propylene glycol / Paracetamol (toxicity)
         I - Isoniazid / Iron
         L - Lactic acidosis
         E - Ethanol/Ethylene glycol
         S - Salicylates

STEP 6: If AG elevated, calculate DELTA-DELTA ratio
         Δ/Δ = (AG - 12) / (24 - HCO₃)
         Δ/Δ < 1.0  → concurrent NON-AG metabolic acidosis
         Δ/Δ 1-2    → pure AG metabolic acidosis
         Δ/Δ > 2.0  → concurrent metabolic ALKALOSIS

Non-AG Metabolic Acidosis Causes (HARDDUP)

H - Hyperchloridemia (excess saline)
A - Addison's disease
R - Renal tubular acidosis (RTA)
D - Diarrhea (GI bicarbonate loss)
D - Drugs (acetazolamide)
U - Uretero-sigmoidostomy
P - Post-hypocapnia

Oxygenation Assessment

P/F Ratio = PaO₂ / FiO₂
Normal: > 400
Mild ARDS:   200-300
Moderate ARDS: 100-200
Severe ARDS:  < 100

A-a Gradient = (FiO₂ × 713) - (PaCO₂/0.8) - PaO₂
Normal: < 10-15 mmHg (increases slightly with age)
Elevated A-a gradient = V/Q mismatch, shunt, diffusion problem

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7. EMERGENCY & COMMON ICU DRUGS

Vasopressors & Inotropes

Golden Rule: Vasopressors should ALWAYS run through a central line. NEVER peripherally (causes tissue necrosis).

Sedation & Analgesia (ICU)

Cardiac Arrest Drugs (ACLS)

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8. IMPORTANT ICU TESTS & MONITORING

Routine ICU Labs (Daily)

Key Monitoring Targets in ICU

MAP (Mean Arterial Pressure) ≥ 65 mmHg (>80 in TBI/spinal shock)
SpO₂ target: 94-98% (88-92% in COPD/hypercapnic patients)
Temperature: 36-37.5°C (treat fever/hypothermia aggressively)
Blood glucose: 140-180 mg/dL
Urine output: ≥ 0.5 mL/kg/hr
CVP: 8-12 mmHg (higher in ventilated: 12-15)

Interpreting the CXR in ICU (Daily Read)

Check in order:
1. Lines/Tubes: ETT (3-5cm above carina), CVP (SVC/RA junction), NGT (below diaphragm)
2. Lungs: Pneumothorax (no lung markings, tracheal shift), consolidation, ARDS (bilateral infiltrates)
3. Heart: Cardiomegaly (>50% chest width), widened mediastinum
4. Pleura: Effusion (blunting of costophrenic angle)
5. Bones/Soft tissue: Fractures, surgical emphysema

ECG in ICU - Red Flags

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9. KEY FORMULAS CHEAT SHEET

╔══════════════════════════════════════════════════════════════════╗
║              ICU FORMULAS AT A GLANCE                           ║
╠══════════════════════════════════════════════════════════════════╣
║  MAP = (SBP + 2×DBP) / 3                                       ║
║  Corrected AG = AG + 2.5 × (4 - albumin)                       ║
║  Winter's Formula = 1.5 × HCO₃ + 8 ± 2                        ║
║  Delta-Delta = (AG-12) / (24-HCO₃)                             ║
║  P/F Ratio = PaO₂ / FiO₂  (normal >400, ARDS <300)            ║
║  A-a Gradient = (FiO₂ × 713) - (PaCO₂/0.8) - PaO₂           ║
║  Corrected Na = Na + 1.6 × ((glucose-100)/100)                 ║
║  IBW male = 50 + 2.3 × (Ht in inches - 60)                    ║
║  IBW female = 45.5 + 2.3 × (Ht in inches - 60)                ║
║  Driving Pressure = Plateau - PEEP  (target <15)               ║
║  CrCl = (140-age) × weight / (72 × Cr) [×0.85 in females]    ║
╚══════════════════════════════════════════════════════════════════╝

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QUICK REFERENCE CARD - COMMON ICU EMERGENCIES

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VENTILATOR TROUBLESHOOTING - DOPES MNEMONIC

D - Displacement (ETT out of position or right mainstem)
O - Obstruction (mucous plug, kinked tube, biting ETT)
P - Pneumothorax (tension: tracheal shift, absent breath sounds)
E - Equipment failure (vent circuit leak, disconnection)
S - Stacking (auto-PEEP in obstructive disease)

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• Harrison's Principles of Internal Medicine 22E (2025), Chapter 313 - Mechanical Ventilation
• The Washington Manual of Medical Therapeutics, Chapter 8 - Airway Management & Intubation
• Sabiston Textbook of Surgery 21E, Chapter on Critical Care - Ventilator Modes
• Barash, Cullen & Stoelting's Clinical Anesthesia 9E - ABG Interpretation, Chapter 16

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• PEEP keeps alveoli open; plateau pressure < 30 cmH₂O protects the lung
• Etomidate is your go-to RSI drug when the patient is hemodynamically unstable
• Norepinephrine is first-line vasopressor for septic shock
• ABG interpretation: always do all 6 steps - never stop at pH
• DOPES mnemonic saves lives when ventilated patients desat suddenly