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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High-YieldID

Tuberculosis

Mycobacterium tuberculosis -airborne transmission. Latent TB (positive PPD/IGRA, no symptoms) vs Active TB (cough, fever, night sweats, weight loss, cavitary lesions). Airborne isolation. 4-drug RIPE therapy × 6 months.

🔍 Overview

Latent vs Active TB

Feature	Latent TB (LTBI)	Active TB
Symptoms	None	Cough > 2–3 wks, hemoptysis, fever, night sweats, weight loss
CXR	Normal	Upper lobe cavitary lesions, infiltrates, hilar LAD, Ghon complex
AFB smear	Negative	May be positive (3 sputum samples)
Infectious	No	Yes -airborne isolation required
PPD/IGRA	Positive	Usually positive (can be negative if immunosuppressed)

Airborne isolation (negative pressure room, N95 for staff) for ANY suspected active TB until 3 consecutive negative AFB smears collected 8–24h apart.

Extrapulmonary TB

Site	Presentation	Diagnosis
TB Meningitis	Subacute headache, cranial nerve palsies, basilar meningitis	CSF: lymphocytic, low glucose, high protein. NAAT on CSF.
Miliary TB	Disseminated, diffuse millet-seed nodules on CXR. Immunosuppressed patients.	Culture blood, urine, bone marrow.
TB Lymphadenitis (Scrofula)	Painless cervical LAD, most common extrapulmonary TB	FNA with AFB/culture.
Vertebral (Pott Disease)	Back pain, paraspinal abscess. Can cause cord compression.	MRI spine.
Pleural TB	Exudative effusion, lymphocytic, high ADA (>40)	Pleural biopsy most sensitive.
Pericardial TB	Effusion, may cause tamponade. Common in HIV+.	Pericardial fluid culture, biopsy.
Renal TB	Sterile pyuria, hematuria	Urine AFB cultures.
GI TB	Mimics Crohn disease. Ileocecal region most common.	Colonoscopy with biopsy, AFB culture.

TB Meningitis: Add Dexamethasone to RIPE for TB meningitis - reduces mortality by ~30% Thwaites, 2004. Extend total treatment to 9-12 months. Miliary TB also treated for 9-12 months.

"RIPE" Mnemonic for TB Treatment: R-Rifampin, I-Isoniazid, P-Pyrazinamide, E-Ethambutol. All 4 for initial 2 months, then RI for remaining 4 months = 6 months total.

Side Effects Mnemonic - Remember by the drug's first letter:

Rifampin = Red/orange body fluids
INH = Injury to liver (hepatotoxicity) + Injury to nerves (peripheral neuropathy)
Pyrazinamide = Painful joints (hyperuricemia/gout) + liver Problems
Ethambutol = Eyes (optic neuritis)

🚨 Management

Active TB: RIPE Therapy

Drug	Duration	Major Side Effects
Rifampin (Rifadin)	6 months	Orange body fluids, hepatotoxicity, drug interactions (CYP450 inducer)
Isoniazid (INH)	6 months	Hepatotoxicity, peripheral neuropathy (give Pyridoxine (Vitamin B6) 25–50 mg daily)
Pyrazinamide	2 months	Hepatotoxicity, hyperuricemia/gout
Ethambutol (Myambutol)	2 months	Optic neuritis -check visual acuity monthly. Red-green color blindness.

Latent TB Treatment

Isoniazid (INH) 300 mg daily × 9 months (classic regimen)
Rifampin (Rifadin) 600 mg daily × 4 months (shorter, preferred)
INH + Rifapentine (Priftin) weekly × 12 weeks (3HP regimen -DOT)

Key Evidence: Standard 6-month RIPE remains the backbone of TB treatment BTS, 1998. For LTBI, the 3HP regimen (12-week INH + rifapentine) has equivalent efficacy with superior completion PREVENT TB, 2011. Rifampin x 4 months is now preferred over 9-month INH for LTBI in adults 4R vs 9H, 2018.

🧪 Workup

PPD (tuberculin skin test) -read at 48–72h. Induration (not redness) matters. Cutoff varies by risk.
IGRA (QuantiFERON, T-SPOT) -blood test, single visit, not affected by BCG vaccination
CXR -upper lobe infiltrates, cavitary lesions, Ghon/Ranke complex
3 sputum AFB smears and cultures -collected 8–24h apart. Culture is gold standard (takes 2–6 wks).
NAAT (GeneXpert/Xpert MTB/RIF) -rapid PCR, also detects rifampin resistance
HIV test -all TB patients (TB-HIV coinfection common)

PPD Interpretation Cutoffs

Cutoff	Population
≥ 5 mm	HIV+, close contacts, immunosuppressed, CXR with old TB, organ transplant recipients
≥ 10 mm	Recent immigrants (< 5 yrs), IVDU, healthcare workers, residents of congregate settings, children < 4 yrs, high-risk medical conditions (diabetes, ESRD, silicosis)
≥ 15 mm	Low-risk individuals with no known TB exposure or risk factors

GeneXpert MTB/RIF Ultra: Rapid PCR with results in < 2 hours. Sensitivity ~96% for smear-positive, ~67% for smear-negative pulmonary TB Dorman, 2018. Simultaneously detects rifampin resistance. WHO recommends as initial diagnostic test for all suspected TB.

💊 Medications

Drug	Dose	Key Monitoring
Isoniazid (INH)	5 mg/kg (max 300 mg) daily	LFTs monthly. Give B6 (pyridoxine) to prevent neuropathy.
Rifampin (Rifadin)	10 mg/kg (max 600 mg) daily	LFTs. CYP450 inducer -check all drug interactions.
Pyrazinamide	25 mg/kg daily	LFTs, uric acid (causes hyperuricemia).
Ethambutol (Myambutol)	15–20 mg/kg daily	Visual acuity and color vision monthly.
Pyridoxine (Vitamin B6)	25–50 mg daily	Given with INH to prevent peripheral neuropathy.

📋 On Rounds

Pimp Questions

Why do you give pyridoxine (B6) with isoniazid?

INH inhibits pyridoxal phosphokinase → depletes active vitamin B6 (pyridoxine) → peripheral neuropathy (stocking-glove distribution). Risk factors: malnutrition, pregnancy, HIV, diabetes, alcoholism, renal failure. Give B6 25–50 mg daily to all patients on INH as prophylaxis.

What is the most feared side effect of ethambutol?

Optic neuritis -presents as decreased visual acuity, red-green color blindness, central scotomas. Usually dose-dependent and reversible if caught early. Check baseline visual acuity and color vision, then monthly. Discontinue immediately if visual changes occur.

When is a PPD considered positive at ≥5 mm?

HIV+, close contacts of active TB, immunosuppressed (TNF inhibitors, transplant), CXR with old healed TB. These are the highest-risk groups for reactivation. Lower-risk groups use ≥10 mm or ≥15 mm cutoffs.

Why is IGRA preferred over PPD in BCG-vaccinated patients?

BCG cross-reacts with PPD tuberculin, causing false positive PPD. IGRA uses M. tuberculosis-specific antigens (ESAT-6, CFP-10) not present in BCG or most NTM, so no cross-reactivity. Single blood draw, no return visit needed.

What is the 3HP regimen and why is it preferred for LTBI?

Isoniazid + Rifapentine weekly x 12 doses (DOT). PREVENT TB, 2011 showed equal efficacy to 9-month INH with better completion (82% vs 69%). Shorter = better adherence.

What drug interactions does rifampin cause?

Potent CYP3A4/2C9 inducer. Reduces levels of: warfarin, OCPs, HIV protease inhibitors, calcineurin inhibitors (cyclosporine, tacrolimus), methadone, azole antifungals. In HIV patients, substitute Rifabutin (Mycobutin) instead.

How do you monitor for hepatotoxicity during RIPE therapy?

Baseline LFTs, then monthly if risk factors (alcohol, liver disease, HIV, age >35). Hold all hepatotoxic drugs if AST/ALT >3x ULN with symptoms or >5x ULN without symptoms. Rechallenge sequentially: RIF first, then INH, then PZA.

What defines MDR-TB vs XDR-TB?

MDR-TB = resistant to rifampin + isoniazid. XDR-TB (2021 WHO definition) = MDR + resistant to fluoroquinolone + bedaquiline/linezolid. XDR mortality up to 50-80% in some settings.

When should you suspect TB meningitis?

Subacute headache + cranial nerve palsies (especially CN VI) + basilar meningitis. CSF: lymphocytic pleocytosis, low glucose, high protein, high ADA. Confirm with CSF NAAT. Start empiric RIPE + Dexamethasone per Thwaites, 2004.

Case 1: Active Pulmonary TB

Patient: 34M immigrant, 3-month cough, night sweats, 15 lb weight loss. CXR: upper lobe cavitation. AFB smear 3+ positive. GeneXpert MTB/RIF positive, rifampin sensitive.

Management:

Airborne precautions - negative pressure room, N95 for all staff
Start RIPE therapy: Rifampin (Rifadin) + Isoniazid (INH) + Pyrazinamide (PZA) + Ethambutol (Myambutol) × 2 months, then Rifampin + Isoniazid × 4 months
Add Pyridoxine (B6) 25–50 mg daily with INH to prevent neuropathy
DOT (directly observed therapy) mandatory - improves adherence, prevents resistance
Report to health department - legally required for all active TB cases
HIV test in all TB patients

Key lesson: GeneXpert confirms TB and rules out rifampin resistance within hours. Start RIPE, isolate, report - do all three same day.

Case 2: Latent TB - Immunosuppressed Patient

Patient: 52F with RA, positive IGRA, no symptoms, normal CXR. About to start Adalimumab (Humira) (anti-TNF biologic).

Management:

Rule out active disease first - symptom screen + CXR (active TB must be excluded before treating latent)
Preferred regimen: Rifampin (Rifadin) × 4 months or 3HP - Isoniazid + Rifapentine (Priftin) weekly × 12 doses (directly observed)
Complete LTBI treatment BEFORE starting biologic - anti-TNF agents profoundly impair granuloma formation, risking TB reactivation
Minimum 4 weeks of LTBI treatment should precede biologic initiation when possible

Key lesson: Biologic therapy (especially anti-TNF) is a major reactivation risk. Screen with IGRA before every biologic start. Treat and complete LTBI therapy first.

Case 3: Drug-Resistant TB (MDR-TB)

Patient: 28M with known TB, returns after incomplete treatment. GeneXpert and DST: MDR-TB - resistant to both Rifampin and Isoniazid.

Management:

Infectious disease + public health consultation essential - do not manage MDR-TB alone
Regimen per WHO 2022 guidance: Bedaquiline (Sirturo) + Linezolid (Zyvox) + Levofloxacin (Levaquin) as core agents
Minimum 18-month treatment course - substantially longer than drug-sensitive TB
Monitor for drug toxicities: bedaquiline (QTc prolongation), linezolid (bone marrow suppression, neuropathy), levofloxacin (tendinopathy, QTc)
Airborne isolation maintained; DOT mandatory throughout

Key lesson: MDR-TB = resistant to rifampin + INH. Treatment is prolonged, toxic, and complex - always requires specialist and public health co-management. Incomplete prior treatment is the #1 driver of drug resistance.

⚡ Summary

Latent vs Active

Latent: + PPD/IGRA, no symptoms, normal CXR, not infectious. Active: symptoms, abnormal CXR, infectious.

RIPE Therapy

Rifampin + INH (6 mo) + Pyrazinamide + Ethambutol (2 mo). Always give B6 with INH.

Isolation

Airborne (negative pressure, N95). Until 3 negative AFB smears 8-24h apart.

Side Effects

INH: hepatotoxicity, neuropathy. Rifampin: orange fluids, CYP inducer. Ethambutol: optic neuritis.

Diagnosis

3 sputum AFB smears/cultures. NAAT (GeneXpert) for rapid detection + rifampin resistance.

Always Test

HIV in all TB patients. LFTs at baseline and monthly. Visual acuity if on ethambutol.