Critical Care Unplugged: The ICU Survival Guide They Don’t Teach You in Med School
In critical care, every breath, every number, and every second counts. This guide demystifies ventilation modes, ABGs, vasopressors, GCS, RASS, and more — fast.

If you’ve ever stood in the middle of an ICU, heart pounding, trying to decode the endless beeping of monitors, the hiss of ventilators, and a half-muttered set of arterial blood gas results, trust me—you’re not alone. I’ve been there. And I’ve learned the hard way that in critical care, confidence comes from clarity.

So I’m writing this not from a textbook, but from the trenches—because understanding the real-world essentials of critical care is what separates survival from chaos when the pressure spikes and seconds matter. Whether you're a junior doctor, nurse, or just trying to make sense of what's happening to a loved one in the ICU, this guide is your sanity-saving cheat sheet.

Modes of Ventilation: What the Beeps Really Mean

Ventilation isn’t just about pushing air in and out. It's about timing, pressure, and tailoring support to the patient’s exact needs.

✅ Pro Tip: Know your ventilator’s alarms. A "high pressure" alarm can signal secretions, biting, or poor compliance. A "low pressure" alarm may mean the tube is disconnected or there's a cuff leak.

Arterial Blood Gases (ABGs): The ICU’s Truth Serum

ABGs are like the patient’s SOS signal. Let’s decode:

Common interpretations:

• Respiratory Acidosis: High CO₂ → Think hypoventilation
• Respiratory Alkalosis: Low CO₂ → Think anxiety or overventilation
• Metabolic Acidosis: Low HCO₃⁻ → Shock, DKA
• Metabolic Alkalosis: High HCO₃⁻ → Vomiting, diuretics

 Watch for mixed disorders! A trauma patient in shock may show metabolic acidosis with compensatory respiratory alkalosis.

Vasopressors & Inotropes: Pick Your Poison (Wisely)

Choosing the right vasopressor is not just about "raising the BP". It's about matching the receptor action with the shock type.

 Pro Insight: Noradrenaline is often first-line in septic shock, but in cardiogenic shock, dobutamine is your MVP.

GCS (Glasgow Coma Scale): Talk, Wiggle, Open Your Eyes

We don’t need a neuro consult to assess consciousness. Just remember GCS = E + V + M.

 13-15 = Mild
 9-12 = Moderate
 <8 = Severe (consider intubation)

RASS (Richmond Agitation-Sedation Scale): Is Your Patient Calm or Climbing the Walls?

Aim for -1 to -2 in most ICU sedated patients to allow for neuro checks and safety.

CAM-ICU: Spotting Delirium Before It Hurts

Delirium in the ICU is common but underdiagnosed. The CAM-ICU tool helps us detect it fast.

1. Acute mental status change?
2. Inattention?
3. Altered level of consciousness?
4. Disorganized thinking?

If yes to 1 + 2, and either 3 or 4 → Positive for delirium

Consider haloperidol, dexmedetomidine, or non-pharmacological support like reorientation and sleep hygiene.

U&E’s, LFTs, and Other ICU Labs That Can’t Wait

Monitoring labs in critical care isn’t a “next shift” thing. It’s now.

Urea & Electrolytes (U&Es)

Red Flags:

• Hyperkalemia → cardiac arrest risk
• Hyponatremia → seizures, cerebral edema

LFTs (Liver Function Tests)

Low albumin? Think sepsis, liver failure, or protein loss.

Neurological Pupil Assessments

A quick but powerful check:
Use a pupil gauge (2 to 6 mm scale). Non-reactive or unequal pupils = call neuro now.

The ICU Mantra: "Trust the basics. Act fast. Reassess often."

No matter how complex things get, critical care often boils down to the fundamentals:

• Oxygen delivery
• Perfusion
• Consciousness
• Fluid and electrolyte balance

Get these right, and you’re halfway there.

FAQ: Critical Care Cheat Sheet Essentials

Q1: What’s the first thing to check when a patient deteriorates on a ventilator?
A: Always check DOPES — Displacement, Obstruction, Pneumothorax, Equipment failure, Stacking (auto-PEEP).

Q2: When should I start vasopressors in shock?
A: If the patient remains hypotensive despite 30 mL/kg IV fluids (or shows signs of organ hypoperfusion), start vasopressors—preferably noradrenaline.

Q3: How often should GCS and RASS be reassessed?
A: Every shift at minimum, or more frequently if sedating/changing neurological status.

Q4: How do I interpret mixed acid-base disorders?
A: Use the Winter’s formula for respiratory compensation in metabolic acidosis:
Expected PaCO₂ = (1.5 × HCO₃⁻) + 8 ±2
If actual PaCO₂ is off, suspect a mixed disorder.

Q5: What’s the goal MAP in most ICU patients?
A: Aim for a MAP ≥ 65 mmHg, unless contraindicated (e.g., chronic hypertensives may need higher).

This Isn’t Just Medicine. It’s War Room Decision-Making.

There’s no script in the ICU. You learn to read silence. You notice the change in the beep before anyone else. And sometimes, the only thing standing between life and death is your grasp of the basics.

So keep this cheat sheet close. Use it as your compass. And when chaos hits, remember—clarity saves lives.

Disclaimer: I am not a doctor. This post is for informational purposes only. The information in this article is collected from various reputable and trusted sources, including content created by medical professionals and doctors. Always consult a qualified healthcare provider for medical advice, diagnosis, or treatment.