When to intubate in GCS?

GCS ≤ 8 requires intubation for airway protection. The patient cannot protect their own airway at this level of consciousness. Motor score is the most prognostically important component.

What is the best initial fluid for sepsis resuscitation?

Lactated Ringer's (LR) is the preferred resuscitation fluid. The SMART trial (2018) showed balanced crystalloids reduced death, new renal failure, and persistent renal dysfunction compared to normal saline.

When to start vasopressors in septic shock?

Start norepinephrine (first-line vasopressor) if MAP remains < 65 mmHg after initial 30 mL/kg crystalloid resuscitation, or earlier if patient is profoundly hypotensive. Do not delay pressors to complete full fluid resuscitation.

Why can serum uric acid be normal during acute gout?

During acute inflammation, IL-6 increases renal urate excretion and redistributes urate from plasma to tissues. Up to 40% of acute gout flares have normal serum uric acid. Joint aspiration with polarized microscopy is needed for definitive diagnosis.

How do you distinguish lupus flare from infection in SLE?

Key clues: CRP is low/normal in flare but elevated in infection. Complement (C3/C4) drops in flare but is normal/elevated in infection. Procalcitonin is elevated in bacterial infection but normal in flare. Anti-dsDNA rises in flare, stable in infection.

What is the difference between DKA and HHS?

DKA features acidosis (pH 600), hyperosmolality (> 320), and minimal ketosis -typically in Type 2 DM. DKA requires insulin drip; HHS requires aggressive fluid resuscitation first.

When to give tPA in acute ischemic stroke?

IV alteplase (tPA) can be given within 4.5 hours of last known well time in eligible patients. CT head must rule out hemorrhage first. For large vessel occlusion, mechanical thrombectomy can be performed up to 24 hours with favorable imaging.

What antibiotics for community-acquired pneumonia?

Inpatient non-ICU: ceftriaxone + azithromycin. ICU: ceftriaxone + azithromycin (add vancomycin if MRSA risk). Outpatient healthy: amoxicillin. Outpatient with comorbidities: augmentin + azithromycin or respiratory fluoroquinolone. Duration: 5 days if clinically stable for 48 hours.

How to interpret iron studies?

Iron deficiency: low ferritin (< 30), high TIBC, low iron, low transferrin saturation (< 20%). Anemia of chronic disease: normal/high ferritin (acute phase reactant), low TIBC, low iron. A ferritin of 50-100 in an inflamed patient may still represent iron deficiency.

What is the correction rate for hyponatremia?

Correct sodium no more than 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome (ODS). For symptomatic severe hyponatremia with seizures, give 3% hypertonic saline 100-150 mL bolus over 10-20 minutes. If overcorrected, use D5W + DDAVP rescue protocol.

When to start antibiotics in meningitis?

Within 30-60 minutes. Do NOT delay antibiotics for LP or CT. Draw blood cultures, start empiric antibiotics (vancomycin + ceftriaxone ± ampicillin if > 50 or immunocompromised), then perform LP when possible. Dexamethasone should be given before or with the first antibiotic dose.

DOACs vs warfarin in antiphospholipid syndrome?

DOACs are contraindicated in APS. The TRAPS trial (2018) showed rivaroxaban was inferior to warfarin with more thrombotic events in triple-positive APS patients. Warfarin with INR target 2-3 is the standard for APS, indefinitely.

How to manage scleroderma renal crisis?

ACE inhibitors (captopril) are life-saving -start immediately and titrate aggressively. Do NOT hold for rising creatinine. Steroids > 15 mg prednisone per day precipitate scleroderma renal crisis. ARBs are NOT a substitute -evidence is only for ACEi.

What are the 4 pillars of heart failure treatment?

Guideline-directed medical therapy (GDMT) for HFrEF: (1) ARNI or ACEi/ARB, (2) beta-blocker (carvedilol, metoprolol succinate, or bisoprolol), (3) MRA (spironolactone or eplerenone), (4) SGLT2 inhibitor (dapagliflozin or empagliflozin). All four should be initiated and titrated to target doses.

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CoreQuick Reference

IV Fluid Guide

Which fluid, how much, and when. NS vs LR vs D5 vs albumin -the answer depends on the clinical scenario. Stop giving everyone "NS at 125."

💧 Fluid Selection

Crystalloids

Fluid	Na⁺	Cl⁻	K⁺	Buffer	Osmolality	Use
NS (0.9% NaCl)	154	154	0	None	308	Volume resuscitation (default bolus fluid), hypernatremia correction, metabolic alkalosis (Cl⁻-responsive -NS provides chloride). Caution: large volumes → hyperchloremic metabolic acidosis.
LR (Lactated Ringer's) PREFERRED	130	109	4	Lactate 28	273	Preferred resuscitation fluid for most patients. SMART, 2018: balanced crystalloids (LR) reduced death, new renal failure, and persistent renal dysfunction vs NS. Less hyperchloremic acidosis.
D5W	0	0	0	None	252	Free water replacement (hypernatremia, DI). NOT for volume resuscitation (glucose is metabolized → leaves free water → distributes into all compartments). Correct hypernatremia: D5W or ½NS.
½NS (0.45% NaCl)	77	77	0	None	154	Maintenance fluid (with 20 mEq KCl/L = "D5 ½NS + 20 KCl"). Hypernatremia correction. Hypotonic -NOT for boluses.
D5NS	154	154	0	None	560	Adrenal crisis (dextrose + volume). DKA maintenance (once glucose < 250, switch from NS to D5NS to continue insulin).
D5W + NaHCO₃ (Bicarb drip)	Varies	0	0	NaHCO₃	Varies	Common recipe: 150 mEq NaHCO₃ (3 amps of 50 mEq) in 1L D5W → run at 150–200 mL/hr. Uses: • Salicylate (aspirin) toxicity -urine alkalinization (goal urine pH 7.5–8.0) enhances renal excretion • TCA overdose -serum alkalinization overcomes sodium channel blockade (wide QRS → give until QRS narrows) • Severe metabolic acidosis (pH < 7.1) -bridge while treating underlying cause • Hyperkalemia (temporizing -shifts K⁺ intracellularly, less reliable than insulin/glucose) • Rhabdomyolysis -urine alkalinization (goal urine pH > 6.5) prevents myoglobin precipitation in tubules • Tumor lysis syndrome -historically used for urine alkalinization (now rasburicase preferred) ⚠️ Do NOT mix with calcium in same line (precipitates). Monitor for hypernatremia, metabolic alkalosis, hypokalemia.
3% Hypertonic saline	513	513	0	None	1027	Symptomatic severe hyponatremia (seizures, coma): 100–150 mL bolus over 10–20 min. Also for cerebral edema (herniation). ICU only. Never give peripherally at high rates.

Fluid Categories -Resuscitation vs Maintenance vs Replacement vs Specialty

Category	Purpose	Fluids Used	Rate	Key Rules
🔴 Resuscitation (Volume expansion)	Restore intravascular volume in shock, sepsis, hemorrhage, severe dehydration	LR (preferred) SMART, 2018 NS (acceptable) Albumin 5% (if refractory)	Bolus: 500 mL–1L over 15–30 min. Sepsis: 30 mL/kg in first 3h.	• Isotonic fluids ONLY -~25% stays intravascular (¼ of crystalloid bolus), rest goes interstitial • Colloids (albumin): ~100% stays intravascular in healthy physiology. ⚠️ In sepsis/critical illness, capillary leak allows albumin to extravasate into interstitium → loses its advantage. This is why balanced crystalloids (LR) remain first-line for sepsis resuscitation, NOT albumin SAFE, 2004 ALBIOS, 2014 • NEVER use D5W or ½NS for resuscitation -D5W: only ~8% stays intravascular (distributes as free water across all compartments). ½NS: only ~17% stays intravascular • Reassess after each bolus (JVP, lung exam, MAP, UOP, lactate) • Stop when target MAP ≥ 65 or signs of fluid overload
🟡 Maintenance (Daily needs)	Replace insensible losses + obligatory urine output in NPO patients who are euvolemic	D5 ½NS + 20 KCl/L (standard) D5NS (if Na⁺ low or adrenal crisis) D5 ¼NS (pediatrics)	4-2-1 rule: First 10 kg: 4 mL/kg/hr Next 10 kg: 2 mL/kg/hr Each additional kg: 1 mL/kg/hr (~75–125 mL/hr for adults)	⚠️ NOT everyone gets maintenance fluids! • ✅ Give if: NPO + euvolemic • ❌ Do NOT give if: eating/drinking, HF, cirrhosis, SIADH, CKD/ESRD, volume overloaded, post-resuscitation • Hypotonic (½NS) because kidneys retain Na⁺ and excrete free water normally • Dextrose prevents starvation ketosis (~170 kcal/L) • Add KCl 20 mEq/L (daily K⁺ need ~40–60 mEq) • NOT for volume resuscitation -hypotonic fluids don't stay intravascular
🔵 Replacement (Specific deficits)	Replace specific electrolyte or water deficits	D5W -free water (hypernatremia, DI) ½NS -mild hypernatremia 3% Hypertonic -severe hyponatremia NS -Cl⁻-responsive metabolic alkalosis	Depends on deficit calculation and correction rate limits	• Hypernatremia: correct ≤ 10 mEq/L per 24h • Hyponatremia: correct ≤ 8 mEq/L per 24h (risk of ODS if too fast) • Match the fluid to the deficit -don't just give NS for everything
🟣 Specialty (Drug vehicles / specific protocols)	Carry medications or correct specific metabolic derangements	D5W + NaHCO₃ -bicarb drip (salicylate/TCA OD, rhabdo, acidosis) D5NS -DKA (when BG < 250, switch to D5 to continue insulin) D5W -drug carrier (amiodarone, many drips) Albumin 25% -oncotic pull in HF + hypoalbuminemia	Protocol-specific	• Bicarb drip: never mix with calcium in same line • DKA: D5 prevents hypoglycemia while insulin clears ketones • Some drugs are ONLY compatible with D5W (amiodarone, phenytoin)

⚠️ The #1 mistake: Using D5W or ½NS for volume resuscitation.
1L NS or LR → ~250 mL stays intravascular (25%)
1L ½NS → ~170 mL stays intravascular (17%)
1L D5W → ~83 mL stays intravascular (8%) -basically free water
1L Albumin 5% → ~1000 mL stays intravascular (100%) in healthy capillaries. In sepsis/capillary leak → albumin extravasates and this advantage is lost.
First-line resuscitation = balanced crystalloids (LR). Albumin is reserved for specific indications (SBP, HRS, post-LVP) or refractory shock after crystalloid.

Colloids

Fluid	Use	Do NOT Use
Albumin 5%	SBP (1.5 g/kg day 1, 1 g/kg day 3). HRS (with midodrine + octreotide). Post-LVP > 5L (6–8 g/L removed). Sepsis (if not responding to crystalloid).	Traumatic brain injury SAFE, 2004: increased mortality.
Albumin 25%	Volume expansion with minimal fluid volume (useful in HF + hypoalbuminemia → draws fluid from interstitium into intravascular space).	Same as 5%. Expensive.

Avoid hydroxyethyl starch (HES / Voluven) -increases AKI and mortality in critically ill patients VISEP, 2008 6S, 2012. FDA black box warning. Use crystalloids or albumin instead.

Quick Decision Guide

Scenario	Best Fluid
Sepsis / Shock resuscitation	LR boluses (30 mL/kg). Albumin if refractory.
DKA	NS initially (volume-depleted + hyponatremia common). Switch to D5½NS when glucose < 250.
Hypernatremia	D5W or ½NS (free water). Correct ≤ 10 mEq/L per 24h.
Hyponatremia (symptomatic)	3% hypertonic saline 100–150 mL bolus. ≤ 8 mEq/L per 24h.
Metabolic alkalosis (Cl-responsive)	NS (provides chloride to correct the alkalosis).
Maintenance (NPO patient)	D5½NS + 20 KCl at 75–125 mL/hr (or use 4-2-1 rule).
Pancreatitis	LR (preferred over NS -less SIRS, less AKI).
Salicylate (ASA) toxicity	D5W + NaHCO₃ drip (150 mEq in 1L D5W). Goal urine pH 7.5–8.0. Enhances renal excretion.
TCA overdose (wide QRS)	NaHCO₃ bolus (1–2 mEq/kg IV push), then bicarb drip. Give until QRS narrows.
Rhabdomyolysis	Aggressive LR + consider bicarb drip (goal urine pH > 6.5 to prevent myoglobin cast nephropathy).
Severe metabolic acidosis (pH < 7.1)	NaHCO₃ drip as bridge. Treat underlying cause. Not beneficial in DKA (insulin fixes it).
HF / volume overloaded	No fluids. Diurese. If needs meds → use smallest volume (hep-lock, concentrated drips).
Cirrhosis + SBP	Albumin (not crystalloid -albumin reduces HRS and mortality).

📐 Rates & Formulas

Who Actually Needs Maintenance Fluids?

✅ Give Maintenance Fluids	❌ Do NOT Give Maintenance Fluids
NPO (nothing by mouth) -surgery, intubated, bowel obstruction, severe vomiting	Eating and drinking normally -just saline-lock the IV
Euvolemic -not dehydrated, not overloaded	Heart failure -extra fluid worsens congestion
No IV fluid restriction	Cirrhosis with ascites -fluid restricted (1–1.5L/day)
Unable to match insensible losses orally	SIADH / hyponatremia -fluid restriction is first-line treatment
	CKD/ESRD on dialysis -can't excrete the volume
	Volume overloaded for any reason -pulmonary edema, anasarca
	Post-resuscitation -once volume restored, STOP. Don't leave "NS at 125" running.

⚠️ The classic intern mistake: Admitting a patient and reflexively ordering "D5½NS at 125 mL/hr" without asking: can this patient eat? Are they fluid-restricted? Three days later they're 5 kg up with new pulmonary edema.

Rule: If the patient can eat → no maintenance fluids. If they can't eat but are volume overloaded → no maintenance fluids. Maintenance fluids are ONLY for the NPO + euvolemic patient.

Maintenance Rate -4-2-1 Rule

First 10 kg: 4 mL/kg/hr
Next 10 kg: 2 mL/kg/hr
Each additional kg: 1 mL/kg/hr
Example: 70 kg patient → (4×10) + (2×10) + (1×50) = 40 + 20 + 50 = 110 mL/hr

Free Water Deficit (for Hypernatremia)

FWD = TBW × (Na/140 − 1)

TBW = weight (kg) × 0.6 (male) or × 0.5 (female). Replace deficit over 48–72h (correct ≤ 10 mEq/L per 24h). Add ongoing losses (insensible + urine).

Which Fluid for Hypernatremia? -Decision Tree

The deficit formula tells you how much. This tells you which fluid:

Volume Status	Step 1	Step 2 (Correction)	Free Water per Liter
Hypovolemic (most common -dehydration, vomiting, diarrhea, poor PO intake)	NS bolus first -restore intravascular volume. NS is "hypotonic" relative to the patient's serum Na⁺ (154 vs 160+), so it will still lower Na⁺ slightly.	Once hemodynamically stable → switch to ½NS (provides Na⁺ + free water)	½NS = 500 mL free water/L NS = 0 mL (but still relatively hypotonic to patient)
Euvolemic (pure water loss -diabetes insipidus, insensible losses, inadequate water intake)	D5W -pure free water replacement. No volume deficit to correct first.		D5W = 1000 mL free water/L
Hypervolemic (rare -iatrogenic hypertonic saline, sodium bicarb excess)	D5W + furosemide -diuretic removes excess Na⁺ while D5W replaces free water		D5W = 1000 mL free water/L + furosemide excretes Na⁺-rich urine

⚠️ Classic pimp question: "Na⁺ is 158 and the patient is hypotensive -do you start D5W?"
NO. D5W is free water -only ~8% stays intravascular. A hypotensive patient needs volume first (NS bolus), then switch to ½NS or D5W for Na⁺ correction once hemodynamically stable. Fix the volume, then fix the sodium.

Free water content of common fluids:
D5W: 1000 mL free water per liter (100%)
¼NS (0.2%): 750 mL free water per liter (75%)
½NS (0.45%): 500 mL free water per liter (50%)
NS (0.9%): 0 mL free water per liter (0% -isotonic)
Oral water / NG flushes: 1000 mL per liter (100%) -best option if patient can tolerate PO

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