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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Hematology

Anticoagulation Management

Warfarin vs DOACs vs heparin: choosing, dosing, monitoring, bridging, and reversal. The most commonly consulted hematology topic on wards.

🔍 Overview

Overview

Anticoagulation management is one of the most common daily tasks on inpatient medicine. Key decisions: (1) Which agent? Heparin (UFH for acute, can titrate, dialyzable) vs LMWH (predictable, SQ, no monitoring) vs warfarin (outpatient, INR monitoring, cheap) vs DOAC (outpatient, no monitoring, fewer interactions, not all indications). (2) When to bridge? Only high-risk patients (mechanical valve, recent VTE < 3 months, prior thrombosis on interruption). (3) How to reverse? Warfarin: vitamin K ± 4-factor PCC. DOACs: idarucizumab (dabigatran), andexanet alfa (Xa inhibitors), or 4F-PCC. Heparin: protamine. Key intern skill: recognizing bleeding vs thrombotic risk and adjusting therapy accordingly.

Warfarin-only indications (DOACs are contraindicated): (1) Mechanical heart valves - RE-ALIGN trial showed excess valve thrombosis with dabigatran. (2) Triple-positive antiphospholipid syndrome - TRAPS trial showed excess arterial events with rivaroxaban. (3) Moderate-severe mitral stenosis. For ALL other indications (nonvalvular AF, VTE), DOACs are preferred over warfarin. RE-ALIGN, 2013

When to choose each anticoagulant: UFH = acute (titratable, reversible, dialyzable). LMWH = predictable SQ dosing, cancer VTE. Warfarin = mechanical valve, APS, severe CKD (CrCl < 15), cost. DOAC = everything else (AF, VTE) - fewer interactions, no monitoring, rapid onset. Fondaparinux = HIT with VTE (no heparin cross-reactivity).

🧪 Workup

Workup

Before starting anticoagulation: CBC, PT/INR, aPTT, Cr + CrCl (DOAC dosing), LFTs (hepatic clearance), HAS-BLED score (bleeding risk)
Warfarin monitoring: INR (target 2-3 for most indications; 2.5-3.5 for mechanical mitral valve). Check INR daily inpatient until stable, then q1-4 weeks outpatient.
Heparin monitoring: aPTT q6h after initiation or dose change (anti-Xa levels if aPTT unreliable -lupus anticoagulant, elevated baseline). Target aPTT per institutional protocol (usually 1.5-2.5× control).
LMWH: No routine monitoring. Check anti-Xa level (peak, 4h post-dose) if: obesity (> 150 kg), CKD (CrCl < 30 → use UFH instead), pregnancy.
DOACs: No routine monitoring. Check Cr + CrCl (dose-adjust apixaban/rivaroxaban at CrCl 15-30; dabigatran CI if CrCl < 30). Drug-specific anti-Xa (rivaroxaban, apixaban) or dTT (dabigatran) for special situations (overdose, pre-surgery, bleeding).
Indication verification: AF (CHA₂DS₂-VASc ≥ 2 men, ≥ 3 women), VTE treatment, mechanical valve (warfarin only), antiphospholipid syndrome (warfarin preferred over DOACs TRAPS, 2018)

🚨 Management

Management

VTE treatment: DOAC preferred (rivaroxaban or apixaban). Duration: provoked DVT = 3 months; unprovoked = extended (reassess annually). Cancer-associated VTE: LMWH or DOAC (edoxaban, rivaroxaban) [HOKUSAI VTE Cancer, 2018; SELECT-D, 2018]. Exception: GI/GU cancer with high bleed risk → LMWH preferred.
AF anticoagulation: DOAC preferred over warfarin for nonvalvular AF [RE-LY, ROCKET AF, ARISTOTLE, ENGAGE AF-TIMI 48]. Exception: moderate-severe mitral stenosis or mechanical valve → warfarin only.
Perioperative bridging:
- Most patients: do NOT bridge. BRIDGE, 2015 -bridging with LMWH in AF patients on warfarin increased bleeding without reducing thrombosis.
- Bridge ONLY if: mechanical mitral valve, mechanical aortic valve + additional risk factor, VTE within 3 months, prior thrombosis during anticoagulation interruption.
- Stop warfarin 5 days before. Stop DOAC 2-3 days before (longer if CKD). Resume 24-72h post-procedure depending on bleeding risk.

DOAC perioperative management is simpler than warfarin: No bridging needed. Simply hold the DOAC 24-48h pre-procedure (48-72h if CrCl < 50 or high-bleed-risk surgery). Resume 24-48h post-procedure. The PAUSE trial validated this approach with low rates of both thromboembolism (0.16%) and major bleeding (1.35%). PAUSE, 2019

Reversal:
- Warfarin: Vitamin K 10 mg IV (takes 6-24h). For urgent: 4-factor PCC (Kcentra) 25-50 units/kg (immediate). FFP only if PCC unavailable.
- Dabigatran: Idarucizumab (Praxbind) 5g IV -immediate, complete reversal. RE-VERSE AD, 2017
- Xa inhibitors (rivaroxaban/apixaban/edoxaban): Andexanet alfa (Andexxa) -expensive, limited availability. Alternative: 4-factor PCC 50 units/kg. ANNEXA-4, 2019
- Heparin: Protamine 1 mg per 100 units UFH given in last 2-3h (max 50 mg). Only 60% effective for LMWH.

Supratherapeutic INR management: INR 4.5-10, no bleeding: hold warfarin, recheck INR in 24-48h. Consider vitamin K 1-2.5 mg PO if high bleeding risk. INR > 10, no bleeding: vitamin K 5-10 mg PO, recheck in 24h. ANY INR + serious/life-threatening bleeding: 4-factor PCC 25-50 U/kg + vitamin K 10 mg IV + hold warfarin. FFP only if PCC unavailable (slower, volume overload).

💊 Medications

Medications

Warfarin (Coumadin)	Individualized (typically 2-10 mg daily)	PO	Required for mechanical valves + APS. INR monitoring. Drug/food interactions. Vitamin K dependent factors (II, VII, IX, X, protein C/S).
Heparin (UFH)	80 U/kg bolus → 18 U/kg/hr	IV	Titratable, short half-life, dialyzable. Monitor aPTT q6h. Protamine for reversal. HIT risk.
Enoxaparin (Lovenox)	1 mg/kg BID or 1.5 mg/kg daily	SQ	Predictable pharmacokinetics. Avoid if CrCl < 30 (accumulates). Anti-Xa for monitoring in special populations.
4-Factor PCC (Kcentra)	25-50 U/kg IV	IV	Warfarin reversal (immediate). Also used off-label for Xa inhibitor reversal. Contains factors II, VII, IX, X + protein C/S.

DOAC dosing by indication: Apixaban: AF = 5 mg BID (2.5 mg if >= 2 of: age >= 80, weight <= 60 kg, Cr >= 1.5). VTE = 10 mg BID x 7d then 5 mg BID. Rivaroxaban: AF = 20 mg daily WITH FOOD (bioavailability drops 39% without food). VTE = 15 mg BID x 21d then 20 mg daily. Edoxaban: 60 mg daily (30 mg if CrCl 15-50 or weight <= 60 kg). Requires 5-day heparin lead-in. ARISTOTLE, 2011

Monitoring

🏥 Rounds

Pimp Questions

❓ When should you bridge anticoagulation perioperatively and when should you not?

Do NOT bridge most patients. BRIDGE, 2015 showed that bridging AF patients on warfarin with LMWH increased major bleeding 3-fold without reducing stroke. Bridge ONLY: mechanical mitral valve, mechanical aortic valve + additional risk factor (AF, prior stroke, EF < 35%), VTE within 3 months, prior thromboembolism during anticoagulation interruption.

❓ Why are DOACs preferred over warfarin for nonvalvular AF?

Four landmark trials showed DOACs are non-inferior or superior to warfarin for stroke prevention with lower rates of intracranial hemorrhage: RE-LY (dabigatran), ROCKET AF (rivaroxaban), ARISTOTLE (apixaban -also reduced mortality), ENGAGE AF (edoxaban). Additional advantages: no INR monitoring, fewer food/drug interactions, predictable pharmacokinetics, rapid onset.

❓ How do you reverse each anticoagulant?

Warfarin: Vitamin K 10 mg IV (slow, 6-24h) + 4-factor PCC 25-50 U/kg (immediate). Dabigatran: Idarucizumab 5g IV (immediate, complete). Xa inhibitors: Andexanet alfa (expensive) or 4F-PCC 50 U/kg (off-label). Heparin: Protamine 1 mg/100 U UFH. LMWH: Protamine partially effective (~60%). For all: hold drug, apply pressure, transfuse if needed.

❓ Why is warfarin preferred over DOACs in antiphospholipid syndrome?

TRAPS, 2018 -trial of rivaroxaban vs warfarin in triple-positive APS was stopped early for excess thrombotic events in the rivaroxaban arm (arterial events). DOACs may be acceptable for single/double-positive APS with venous-only events, but triple-positive APS must be on warfarin. Warfarin is also required for mechanical heart valves (DOACs showed excess valve thrombosis in RE-ALIGN).

❓ What is the CHA₂DS₂-VASc score and when do you anticoagulate?

C HF (1) · H TN (1) · A ge ≥ 75 (2) · D M (1) · S troke/TIA (2) · V ascular disease (1) · A ge 65-74 (1) · S ex female (1). Score 0 (men) or 1 (women): no anticoagulation. Score 1 (men) or 2 (women): consider. Score ≥ 2 (men) or ≥ 3 (women): anticoagulate. DOAC preferred unless valvular AF or APS.

❓ A patient on warfarin has an INR of 8.5 with no bleeding. How do you manage this?

Hold warfarin + give vitamin K 2.5-5 mg PO (oral is preferred over IV for non-bleeding supratherapeutic INR). Recheck INR in 24h. Do NOT give PCC or FFP (no active bleeding). If INR > 10 without bleeding, give vitamin K 5-10 mg PO. Resume warfarin at a reduced dose once INR < 3. Common causes of supratherapeutic INR: drug interaction (antibiotics, amiodarone, azole antifungals), dietary change (decreased vitamin K intake), liver disease, alcohol binge.

❓ What are the absolute contraindications to anticoagulation?

Active life-threatening hemorrhage, hemorrhagic stroke (acute phase), severe uncontrolled hypertension (relative), intracranial hemorrhage, major surgery within 24h, platelet count < 25K (relative at < 50K), active GI bleeding. For patients with both high thrombotic AND high bleeding risk (e.g., recent GI bleed + mechanical valve), consult hematology. An IVC filter may be a temporary bridge if anticoagulation must be held. HAS-BLED score >= 3 = high bleeding risk but is NOT a contraindication to anticoagulation.

❓ When should you use heparin drip vs LMWH vs a DOAC for acute VTE?

Heparin drip: when you need tight control and rapid reversibility - massive PE (may need tPA), high bleeding risk, renal failure (CrCl < 30), perioperative patients. LMWH: stable VTE, predictable dosing, can discharge on it. DOACs: stable VTE for discharge - apixaban or rivaroxaban need no heparin lead-in (load and go). Edoxaban/dabigatran need 5-day heparin lead-in first. Cancer VTE: LMWH or edoxaban/rivaroxaban (not warfarin). AMPLIFY, 2013

❓ How do you manage a patient on a DOAC who needs emergency surgery?

Check last dose timing. If last dose < 24h ago AND high-risk surgery: consider reversal (idarucizumab for dabigatran, andexanet alfa or 4F-PCC 50 U/kg for Xa inhibitors). If last dose > 24-48h ago: most DOACs are sufficiently cleared for surgery (longer washout if CrCl reduced). For urgent but not emergent surgery: delay 24-48h if possible. Drug-specific half-lives: dabigatran 12-17h, rivaroxaban 5-13h, apixaban 12h, edoxaban 10-14h. All are prolonged in renal impairment. Standard coagulation tests (PT/INR) do NOT reliably reflect DOAC activity.

Clinical Examples

📋 Case 1, Perioperative Bridging Decision

Patient: 72M, on warfarin for mechanical aortic valve (INR target 2.5-3.5), needs elective hip replacement in 5 days. Current INR 3.0.

Key findings: Mechanical valve = high thromboembolic risk. CHA2DS2-VASc not applicable (valvular indication). No prior stroke or TIA. EF 55%.

Management:

Stop warfarin 5 days pre-op (allow INR to drift to < 1.5)
Mechanical valve = MUST bridge with therapeutic LMWH (enoxaparin 1 mg/kg BID) when INR < 2
Hold LMWH 24h before surgery
Resume warfarin evening of surgery; restart LMWH 24-48h post-op when hemostasis confirmed
Stop LMWH when INR therapeutic (≥ 2.5 for mechanical valve)

Teaching point: Most AF patients do NOT need bridging. BRIDGE, 2015 showed bridging AF patients increased major bleeding 3-fold without reducing stroke. However, mechanical valves remain an absolute bridging indication due to catastrophic thrombotic risk.

📋 Case 2, DOAC Reversal for Life-Threatening Bleeding

Patient: 78F, on apixaban 5 mg BID for AF, presents with massive upper GI bleed (hematemesis, melena). Hemodynamically unstable.

Key findings: HR 118, BP 82/50. Hgb 6.2 (baseline 11.8). INR 1.3 (misleading on DOACs). Last apixaban dose 4 hours ago. Anti-Xa level 180 ng/mL (supratherapeutic).

Management:

Hold apixaban immediately
Reversal: andexanet alfa (Andexxa) IV bolus + infusion if available; otherwise 4-factor PCC 50 U/kg (off-label)
Transfuse pRBC to Hgb > 7; FFP does NOT reverse DOACs
Emergent EGD once hemodynamically stabilized
After bleed resolved: reassess anticoagulation indication and risks vs benefits of resumption

Teaching point: Standard INR does NOT reliably reflect DOAC activity. Anti-Xa levels assess rivaroxaban/apixaban; thrombin time for dabigatran. Andexanet alfa reverses Xa inhibitors but is expensive. 4-factor PCC is the pragmatic alternative. ANNEXA-4, 2019

📋 Case 3, Warfarin-Only Indication in APS

Patient: 34F, triple-positive antiphospholipid syndrome (lupus anticoagulant + anti-cardiolipin + anti-beta2-glycoprotein I), history of DVT + PE at age 28. On rivaroxaban 20 mg daily. Presents with acute left MCA stroke.

Key findings: CT head: no hemorrhage. CTA: left MCA occlusion. Thrombectomy performed. INR 1.1 despite rivaroxaban. Anti-Xa level therapeutic (ruling out non-adherence).

Management:

This is a treatment failure on a DOAC in triple-positive APS
Switch to warfarin (INR target 2-3, some experts target 3-4 for arterial events)
Bridge with UFH drip until INR therapeutic
DOACs are contraindicated in triple-positive APS
Lifelong anticoagulation with warfarin - never switch to DOAC

Teaching point: TRAPS, 2018 was stopped early because rivaroxaban had significantly more arterial thrombotic events than warfarin in triple-positive APS. Warfarin is also the only option for mechanical heart valves (RE-ALIGN, 2013 showed excess valve thrombosis with dabigatran).

Sample Presentation

Mr. Davis is a 74-year-old man on warfarin for mechanical aortic valve (INR target 2.5-3.5) admitted for cholecystectomy. Current INR 3.1. Surgery planned in 3 days. Question: how do you manage his anticoagulation perioperatively?

Key Points: Mechanical valve = high thromboembolic risk → bridge with therapeutic LMWH. Stop warfarin now (5 days pre-op). Start enoxaparin 1 mg/kg BID when INR < 2. Hold LMWH 24h pre-surgery. Restart heparin drip post-op when hemostasis confirmed (12-24h). Resume warfarin evening of surgery. Stop heparin when INR therapeutic.

Warfarin INR: daily inpatient → weekly → q2-4 weeks when stable. Time in therapeutic range (TTR) target > 65%.
Heparin aPTT: q6h after initiation or dose change until 2 consecutive values in range, then q12-24h.
DOACs: Cr annually (more frequent if CKD). No routine drug levels. CBC at baseline + annually.
Bleeding assessment: signs (hemoglobin drop, melena, hematuria, bruising), drug interactions (NSAIDs, antiplatelets, CYP3A4 inhibitors)
HIT screening: platelet count q2-3 days on UFH × first 14 days. 4T score if platelet drop.
CHA₂DS₂-VASc reassessment: annually for AF patients -score can change (new DM, HF, age threshold).

Monitoring

📋 Summary

Summary

DOAC preferred. CHA₂DS₂-VASc ≥ 2M/≥3F → anticoagulate. Warfarin only for mechanical valve or APS.

VTE

DOAC preferred. 3 mo (provoked) vs extended (unprovoked). Cancer: LMWH or DOAC.

Bridging

Most: do NOT bridge BRIDGE, 2015. Bridge only: mechanical valve, VTE < 3 mo.

Reversal

Warfarin: 4F-PCC + vit K. Dabigatran: idarucizumab. Xa: andexanet or 4F-PCC. Heparin: protamine.

Monitoring

Warfarin: INR. Heparin: aPTT q6h. LMWH: anti-Xa (special). DOACs: Cr annually.

Pearl

DOACs contraindicated in APS [TRAPS] + mechanical valves [RE-ALIGN]. Rivaroxaban with food.

📄 One Pager

One-Pager

Anticoagulation

Choose, dose, reverse

Agent Selection

AF/VTE: DOAC first-line. Mechanical valve: warfarin only. APS (triple-positive): warfarin only. Cancer VTE: LMWH or DOAC. Acute inpatient: UFH (titratable) or LMWH.

Reversal Agents

Warfarin → 4F-PCC + vit K. Dabigatran → idarucizumab 5g IV. Xa inhibitors → andexanet alfa or 4F-PCC 50 U/kg. UFH → protamine. LMWH → protamine (partial).

Trials

BRIDGE 2015 · RE-LY · ROCKET AF · ARISTOTLE · TRAPS 2018 · RE-VERSE AD · ANNEXA-4 · HOKUSAI VTE Cancer